1. Introduction
1.1 Research Background
Plastic products play a vital role in modern life, widely used across various sectors. From everyday items like tableware and containers to industrial components and packaging materials, plastics are indispensable due to their versatility and cost-effectiveness. Among these products, PET (polyethylene terephthalate) cups stand out for their unique advantages, making them a key choice in beverage packaging and other applications.
PET cups, known for their lightweight, high transparency, and resistance to impact and cracking, meet consumers ‘needs for convenience, aesthetics, and safety. In the beverage industry, whether it’s carbonated drinks, fruit juices, tea beverages, or mineral water, PET cups have become the primary packaging choice. They effectively prevent carbon dioxide from escaping, maintaining the ‘carbonation’ of the drinks; their high transparency clearly highlights the color and texture of the beverages, attracting consumer attention. Besides beverage packaging, PET cups are also used in food, cosmetics, and medical supplies packaging. As industries evolve, higher demands are placed on the performance and applications of PET cups.
However, while research on PET cups has achieved some success, there is still room for further exploration in areas such as the in-depth analysis of their characteristics, the exploration of new application fields, and a comprehensive evaluation of their comparative advantages with other materials. Therefore, a deeper study of the characteristics, application areas, and advantages of PET cups is crucial for promoting their rational use and development across various industries.
1.2 Purpose and significance of the study
This study aims to comprehensively and systematically analyze the characteristics, application fields and advantages of PET cups. Through multi-dimensional research, this study provides a solid theoretical basis and practical reference for the further promotion and application of PET cups in various industries.
In the field of characteristic research, a thorough analysis of the physical, chemical, and mechanical properties of PET cups can help more accurately determine their application scope and usage conditions. Understanding their heat resistance, cold resistance, and chemical corrosion resistance can provide scientific guidance to manufacturers in selecting raw materials, optimizing production processes, and ensuring quality control, leading to the production of PET cups with superior performance.
Research in the application field not only clarifies the current use of PET cups in various industries but also uncovers potential new applications. By analyzing the needs of different sectors, the study explores the possibilities of PET cups in meeting these needs, providing a direction for market expansion and fostering innovation and development in related industries.
The advantages of PET cups clearly demonstrate their competitiveness compared to other packaging materials. As environmental awareness grows, a deeper understanding of the recyclability and environmental benefits of PET cups can promote their use in sustainable packaging, aligning with current trends. Additionally, recognizing their cost and performance advantages can assist companies in making informed decisions when selecting packaging materials, thereby reducing costs and enhancing product competitiveness.
1.3 Research methods and innovation points
This study employs a variety of research methods to ensure the comprehensiveness and depth of the research. The literature review method serves as the foundation, involving extensive searches of domestic and international literature, including academic journal articles, patent documents, and industry reports. This approach aims to understand the current research status of PET cups, their characteristics, applications, and advantages, thereby providing a theoretical foundation and research direction for future studies.
The case study method selects several representative industry cases, such as the application of PET cups by well-known brands in the beverage industry and the innovative use of PET cups in food packaging. By thoroughly analyzing these real-world cases, we gain a deeper understanding of the effectiveness of PET cups in various scenarios, the challenges they face, and the solutions provided. This approach enriches our practical understanding of PET cups.
The comparative analysis method compares PET cups with other common packaging materials, such as glass bottles, plastic bottles (PP, HDPE, etc.), paper packaging, etc., and compares them from multiple dimensions such as performance, cost, environmental protection, etc., to highlight the advantages and disadvantages of PET cups and provide a basis for their positioning in the market competition.
The innovation of this study lies in a comprehensive analysis of PET cups from multiple perspectives. It not only focuses on their traditional features, applications, and advantages but also explores new application areas and potential benefits. In exploring new application areas, the study aligns with the specific requirements of emerging industries, such as biopharmaceuticals and new energy, to investigate the feasibility of PET cups in these fields, thereby opening up new market opportunities for PET cups. In terms of exploring advantages, the study examines the role of PET cups in the circular economy from a sustainable development perspective, highlighting the new advantages they exhibit after material innovation and process improvements, thus providing new ideas and directions for the development of PET cups.
2, the characteristics of PET cups are analyzed
2.1 Chemical structure and basic properties
2.1.1 Chemical composition of PET
PET, or polyethylene terephthalate, has the chemical formula (C_{10}H_{8}O_{4})_n. It is produced through the esterification and condensation reactions of terephthalic acid (PTA) and ethylene glycol (EG). The molecular structure of PET features a regular linear macromolecular structure, formed by the ester bonds between terephthalic acid residues and ethylene glycol residues. The presence of the benzene ring endows the molecular chain with a certain degree of rigidity, while the ethylene subunits provide flexibility, giving PET both rigidity and flexibility.
The highly regular molecular chains of PET result in strong intermolecular forces, allowing the chains to align closely and facilitate crystallization. Under suitable conditions, PET can form a crystalline state, and variations in crystallinity significantly affect its physical and chemical properties. For example, high-crystallinity PET exhibits higher hardness, strength, and heat resistance, whereas low-crystallinity PET offers better flexibility and transparency. The chemical properties of ester bonds also significantly impact PET’s stability. Ester bonds can undergo hydrolysis reactions under acidic or alkaline conditions, particularly in alkaline environments where these reactions are more pronounced, limiting PET’s application in strongly acidic or alkaline environments. However, under neutral or weakly acidic conditions, PET maintains good chemical stability, ensuring its structure and performance remain stable.
2.1.2 Basic physical properties
PET cups possess a series of unique physical properties that make them excel in various application scenarios. With a density ranging from 1.38 to 1.40g/cm³, PET cups are significantly lighter than traditional packaging materials like glass, making them easier to carry and transport. For instance, a common 500ml PET cup typically weighs only a dozen grams, whereas a glass cup of the same volume might weigh several hundred grams. In the beverage packaging industry, the lightweight nature of PET cups significantly reduces transportation costs and enhances logistics efficiency.
PET cups are known for their high hardness, which helps them maintain a stable shape and resist deformation. Typically, their Shore hardness ranges from D70 to D80, ensuring that even when subjected to external pressure, the cups can remain intact and protect the contents. During normal use and handling, PET cups are unlikely to be crushed or damaged, effectively ensuring the safe storage and transportation of beverages.
One of the key advantages of PET cups is their high transparency, with a light transmittance exceeding 85%, comparable to glass. This high transparency allows consumers to clearly see the color, state, and quality of the drink inside the cup, enhancing the product’s appeal and visual impact. In the beverage industry, the high transparency of PET cups highlights the vibrant colors of fruit juices and the rich bubbles of carbonated drinks, effectively stimulating consumer interest and purchase intent.
2.1.3, chemical stability
PET cups have certain characteristics in terms of chemical stability, making them suitable for a variety of chemical environments. However, they also have some limitations. PET cups are particularly resistant to weak acids. In common acidic beverages, such as fruit juices (with a pH value typically between 2 and 5), PET cups can maintain stability and do not react significantly with the acid, thus preserving the taste and quality of the beverage. When used for packaging fruit juices, PET cups can store the juice for extended periods without causing spoilage or flavor changes.
PET cups also demonstrate good resistance to organic solvents. In products containing small amounts of organic solvents, such as alcoholic beverages or cosmetics, PET cups effectively prevent the penetration of these solvents, thus protecting the cup from erosion and dissolution, and maintaining the integrity of the packaging. For low-alcohol beverages, PET cups can safely store the drinks without issues like swelling or cracking.
PET cups are not stable in all chemical environments. They are not resistant to hot water; when the temperature exceeds 70℃, the thermal movement of PET molecules increases, weakening intermolecular forces and causing the cup to deform easily. High temperatures can also cause the release of additives or oligomers from PET, posing potential health risks. PET cups are less tolerant of alkalis; in an alkaline environment, ester bonds can easily hydrolyze, leading to molecular chain breaks, reduced performance, and even damage. When cleaning PET cups, avoid using strong alkaline cleaners to prevent damage to the cups.
2.2 Thermodynamic properties
2.2.1 Heat resistance
The heat resistance of PET cups is one of their key thermodynamic properties. Typically, PET cups can withstand temperatures up to 70℃, which significantly influences their performance and application in various temperature environments. At room temperature, PET cups maintain a stable physical form and performance, making them ideal for holding a variety of beverages such as mineral water and room-temperature fruit juices. However, as the temperature rises to around 70℃, PET cups begin to show signs of softening and deformation. This occurs because the increased temperature causes the thermal motion of PET molecules to intensify, weakening the intermolecular forces and reducing the cup’s rigidity, making it difficult to retain its original shape. Using PET cups to hold beverages that are too hot, such as freshly boiled water (100℃), can cause the cups to deform rapidly, potentially leading to leaks and posing safety risks.
High temperatures can also cause chemical changes in PET cups. Under high-temperature conditions, additives in PET, such as antioxidants and plasticizers, may decompose or migrate. These changes can lead to the release of harmful chemicals, like bisphenol A (BPA), from the cup. Long-term exposure to these harmful substances can adversely affect the body’s endocrine and reproductive systems, posing a threat to health. When using PET cups, it is important to avoid serving hot beverages to ensure safety.
2.2.2 Cold resistance
In low-temperature environments, the performance of PET cups is also affected. As temperatures drop, the activity of PET molecular chains decreases, and the distance between molecules narrows, leading to increased hardness and brittleness in the cup. During cold winters, when PET cups are exposed to outdoor low temperatures, they may become more fragile and prone to cracking. Low temperatures can also reduce the toughness of PET cups, making them more susceptible to damage from external impacts. If a PET cup is dropped in a low-temperature environment, the likelihood of it breaking is significantly higher compared to when it is at room temperature.
However, PET cups can maintain their performance within a certain low-temperature range. Generally, they can be used normally in temperatures ranging from-20℃ to 0℃, suitable for holding cold drinks like iced beverages and ice cream. Within this temperature range, although the physical properties of the cup may change, it still meets basic usage requirements and avoids serious quality issues. However, if the temperature drops further beyond the tolerance limit of the PET cup, its performance will significantly degrade, making it unusable. When using PET cups in extremely cold regions, it is crucial to pay attention to their cold resistance to prevent damage caused by low temperatures.
2.3 Blockage performance
2.3.1, gas barrier
PET cups have a certain barrier to gases such as oxygen and carbon dioxide, which is of significant value in the packaging industry. For carbonated beverages, PET cups effectively prevent carbon dioxide from escaping. Carbon dioxide in carbonated beverages is crucial for their unique taste and fizziness. The excellent gas barrier of PET cups ensures that carbon dioxide remains in the beverage for a long time, maintaining the ‘fizzy’ sensation and taste of carbonated drinks. Studies show that at room temperature, carbonated beverages packaged in PET cups can maintain a low loss rate of carbon dioxide within the shelf life, typically not exceeding 15%, ensuring that consumers enjoy a taste experience similar to when the beverages were freshly produced.
For easily oxidized beverages, such as fruit juices and tea drinks, PET cups can prevent oxygen from entering, thereby slowing down the oxidation process. Oxygen can cause the nutrients in the beverage to be oxidized and damaged, affecting its quality and taste, and potentially leading to spoilage. The gas barrier properties of PET cups effectively reduce the rate of oxygen penetration, extending the shelf life of the beverage and maintaining its freshness and nutritional value. In juice packaging, PET cups can control the oxygen permeability at a low level, helping to retain vitamin C and other nutrients during storage, reducing oxidation discoloration and flavor loss.
2.3.2, water vapor barrier
PET cups have a certain level of vapor barrier properties, which are essential for maintaining the dryness and preventing moisture absorption in beverages. In humid conditions, PET cups effectively prevent external moisture from entering, thus avoiding the dilution or spoilage of beverages due to water absorption. For beverages that are sensitive to moisture, such as coffee concentrate and honey, the vapor barrier properties of PET cups help maintain the concentration and quality stability of the beverages. Experimental data shows that in high humidity environments (such as relative humidity 80% -90%), PET cups have a low vapor permeability rate over a certain period, which helps keep the internal beverage moisture content within a relatively stable range, preventing quality degradation due to moisture intrusion.
In different humidity environments, the water vapor barrier performance of PET cups varies slightly. As the environmental humidity increases, the driving force for water vapor diffusion also increases, making it more challenging for PET cups to effectively block water vapor. However, they still maintain a good barrier effect overall. In environments with lower relative humidity, the water vapor barrier performance of PET cups is more stable, allowing them to keep beverages dry for extended periods. This makes PET cups suitable for beverage packaging in various climates, providing reliable protection for beverage storage and transportation.
3. Analysis of the application field of PET cups
3.1 Wide application in the beverage industry
3.1.1 Tea and coffee
In the tea and coffee industry, PET cups are widely used. For instance, in milk tea shops that are ubiquitous on the streets, PET cups have become the primary choice for packaging milk tea. The high transparency of PET cups is a key factor in attracting consumers, as it allows them to clearly see the rich ingredients like pearls, coconut flakes, and sweet potatoes, as well as the color of the milk tea, significantly enhancing the product’s appeal. In some milk tea shops that focus on fruit teas, PET cups can display slices of fresh fruits such as oranges, lemons, and strawberries, stimulating consumer interest and encouraging purchases.
The lightweight nature of PET cups also brings numerous conveniences to the operation of tea shops. Compared to traditional ceramic or glass cups, PET cups are lighter, which effectively reduces transportation costs and improves delivery efficiency during the distribution of beverages. For milk tea shops with a high volume of takeout orders, the lightweight nature of PET cups makes delivery easier for riders, reducing the inconvenience caused by heavy cups. PET cups are highly impact-resistant and less likely to break, which better protects the beverages during transportation and storage, reducing the risk of damage. Even during bumpy transportation, PET cups can remain intact, ensuring that the beverages received by consumers are undamaged.
In coffee shops, PET cups play a significant role. For take-out coffee, the portability of PET cups meets consumers’ needs to enjoy coffee anytime and anywhere. Consumers can easily carry their PET cups with coffee in them into their backpacks or pockets for convenient travel. Some coffee shops also feature unique brand logos and design patterns on their PET cups. The high transparency of PET cups makes these printed elements more visible and eye-catching, effectively promoting the brand. Through exquisite designs, PET cups not only serve as containers for coffee but also act as showcases for brand images, helping to enhance brand recognition and reputation.
3.1.2 Fruit juice and carbonated beverage packaging
In the packaging of fruit juices and carbonated drinks, PET cups offer unique advantages by meeting the specific requirements of these beverages. Fruit juices are rich in vitamins, minerals, and organic acids, which are highly susceptible to oxidation and spoilage when exposed to oxygen. PET cups effectively block oxygen, significantly reducing its penetration and slowing down the oxidation process, thus preserving the freshness and nutritional value of the juice. For instance, with freshly squeezed orange juice, using PET cups can extend the shelf life at room temperature to several days. Compared to other packaging materials, this method better preserves the vitamin C and other nutrients in the orange juice, minimizing oxidation, discoloration, and flavor loss.
The unique properties of carbonated beverages demand higher gas barrier requirements for packaging materials. PET cups effectively prevent the escape of carbon dioxide, preserving the ‘carbonation’ and taste of the beverage. During production, carbonated beverages are infused with a large amount of carbon dioxide, creating rich bubbles and a distinctive taste. The gas barrier properties of PET cups ensure that these carbon dioxide gases remain in the beverage for an extended period, maintaining the strong bubble sensation even during storage and transportation. Compared to glass bottles, PET cups are lighter, less prone to breakage, and safer and more convenient for transportation and storage, reducing logistics costs and the risk of damage.
The chemical stability of PET cups makes them ideal for packaging fruit juices and carbonated beverages. These beverages are typically acidic, and PET cups can withstand this acidity without reacting with the drinks, ensuring that the quality and taste of the beverages remain unaffected. During the production and storage of these beverages, PET cups provide a stable and reliable packaging solution, ensuring that consumers receive safe and high-quality products.
3.2 Other applications of food packaging
3.2.1 Snack packaging
PET cups are also used in the snack packaging industry, offering convenience for storing and selling snacks. For example, PET cups can effectively prevent moisture and oxidation, thus extending the shelf life of snacks like potato chips and nuts. These snacks tend to absorb moisture from the air, leading to softening and a loss of texture. PET cups, with their excellent water vapor barrier properties, prevent moisture from penetrating and help maintain the crispness of the snacks. In humid conditions, potato chips packaged in PET cups can remain crispy for extended periods without becoming soft due to moisture absorption.
The oxygen barrier properties of PET cups can slow down the oxidation of oils in snacks, preventing them from developing a rancid taste. Nuts, rich in oils, are prone to oxidation and spoilage when exposed to oxygen, leading to unpleasant odors and harmful substances. The gas barrier properties of PET cups reduce the contact between oxygen and nuts, minimizing oxidation and preserving their freshness and quality. By using PET cups for packaging, the shelf life of nuts can be significantly extended, allowing consumers to enjoy fresher and more delicious nuts.
The high transparency of PET cups not only highlights the color and shape of snacks but also captures consumers ‘attention. On supermarket shelves, transparent PET cups for potato chips and nuts clearly display the contents, allowing consumers to see the quality and quantity of the snacks, thus increasing their desire to purchase. Moreover, the exquisite printing and design on PET cups enhance the product’s aesthetic appeal and brand image, thereby boosting its market competitiveness.
3.2.2, edible ice cup
In recent years, PET cups as edible ice cups have gained increasing attention and become a new trend in the beverage industry. An edible ice cup is a disposable, sealed plastic cup filled with edible ice cubes. Consumers can add their favorite beverages to create unique drinking experiences. One of the key advantages of PET cups as edible ice cups is their stability in low-temperature environments. These cups are typically stored in cold storage at temperatures ranging from-10℃ to-20℃, where they maintain excellent physical properties and are less likely to crack or deform. During transportation and storage, PET cups can withstand the cold, ensuring their integrity and safety, thus providing consumers with reliable use guarantees.
PET cups meet food safety standards, ensuring consumer health. PET resin is a non-toxic and harmless material, free from any harmful additives, and has passed stringent food hygiene inspections. When making edible ice cups, PET cups can come into direct contact with edible ice without releasing harmful substances, thus ensuring the quality and safety of both the ice and the drink. Consumers can use PET edible ice cups with confidence, enjoying cool and delicious drinks.
The transparency and aesthetic appeal of PET cups also make edible ice cups appealing. Transparent PET cups showcase the crystal-clear ice inside, allowing consumers to intuitively experience the coolness and purity of the iced drink. The design and packaging of these iced cups can be innovatively diversified, using attractive patterns and colors to attract consumer attention and meet the demand for personalized and fashionable beverages. In the age of social media, edible ice cups have become a popular choice for consumers to share photos, further boosting their market growth.
3.3 Discussion of other potential application fields
3.3.1 Possibilities in the medical field
In the medical field, PET cups have significant potential for use, particularly in storing medicines and reagents. Medicines and reagents typically have stringent requirements for the chemical stability and safety of their packaging materials. PET cups excel in chemical stability, capable of withstanding the chemical properties of most medicines and reagents without reacting with them, thus ensuring the quality and efficacy of these substances. When storing common oral medicines, PET cups can stably preserve the drugs without affecting their efficacy.
PET cups meet stringent food safety standards, which provides a solid foundation for their use in the medical field. Although the standards for medical supplies differ from those for food, the safety and hygiene of PET cups make them suitable for medical applications with high safety requirements. When used to hold topical medications or cleaning agents, PET cups ensure the purity and safety of the products, preventing contamination from external impurities.
The high transparency of PET cups allows medical staff to easily observe the condition and remaining amount of internal medications or reagents. Accurate understanding of the status of medications and reagents is crucial for effective treatment. The transparent PET cups enable medical staff to clearly see any changes in the color, appearance, and remaining amount of medications, allowing them to replenish or replace items promptly, thus enhancing the efficiency and accuracy of medical procedures.
However, the application of PET cups in the medical field also faces several challenges. The medical industry has extremely high standards for the sterility of packaging materials. During production and use, strict control over microbial contamination is essential to ensure the product remains sterile. Some special drugs and reagents may have higher requirements for the barrier properties of packaging materials, necessitating further research and improvements to enhance the performance of PET cups to meet these specific needs.
3.3.2 Industrial sample containers
In the industrial sector, PET cups have significant potential as sample containers. Industrial samples often need to maintain their original state and properties during storage and transportation, free from external environmental influences. PET cups offer excellent chemical stability and barrier properties, effectively preventing contamination and erosion by external chemicals. When storing chemical reagents or industrial raw material samples, PET cups can block out oxygen, moisture, and other impurities, ensuring the purity and stability of the samples, thus providing reliable sample assurance for industrial production and quality control.
The lightweight and impact-resistant nature of PET cups gives them a significant advantage in the transportation of industrial samples. In industrial production, samples are frequently transported between different locations. The lightweight nature of PET cups reduces transportation costs and enhances efficiency. Their strong resistance to impact means they are less likely to break during transit due to bumps or collisions, thus protecting the samples from damage. For fragile industrial samples, such as glass items, PET cups offer superior protection, ensuring that the samples arrive safely at their destination.
The transparency of PET cups allows staff to easily observe the appearance and condition of samples. In industrial production, inspecting the appearance and condition of samples is a crucial part of quality control. The transparent PET cups enable staff to directly observe the color, shape, and transparency of samples, allowing them to promptly identify any abnormalities, thus facilitating quality control in industrial production.
The cost of PET cups is relatively low, which can significantly reduce the expenses for companies when used extensively as industrial sample containers. For cost-sensitive industrial enterprises, the cost advantage of PET cups makes them an economical and practical choice for sample containers. By carefully selecting the specifications and quality of PET cups, companies can ensure the quality of sample storage and transportation while reducing packaging costs and enhancing economic efficiency.
4. Analysis of advantages of PET cups
4.1 Cost-effectiveness advantage
4.1.1 Raw material cost and production process cost
PET cups offer significant cost benefits, primarily due to their relatively low raw material costs. The primary raw materials for PET, terephthalic acid (PTA) and ethylene glycol (EG), are widely available. With the advancement of the petrochemical industry, these materials are abundant and their prices remain stable. Market data indicates that in recent years, the price fluctuations of PET resin have been relatively minimal. Compared to high-performance plastics like polycarbonate (PC), PET offers a clear price advantage. At the same weight, PET resin is about half the cost of PC resin, which gives PET cups a cost advantage right from the raw material procurement stage.
The production process for PET cups is well-established, which has further reduced production costs. Currently, the production of PET cups mainly uses injection molding and blow molding techniques, both of which are highly advanced and efficient. Modern PET cup production lines are equipped with automated control systems that enable high-speed injection molding and mold opening and closing, significantly boosting production efficiency. During the injection molding process, PET material flows smoothly, allowing for rapid filling of the mold cavity, which reduces the molding cycle and increases output per unit of time. The defect rate during production is relatively low, typically controlled within 5%, which helps to minimize the cost associated with defective products.
The production process for PET cups is relatively simple, requiring minimal equipment and low technical investment. Compared to materials that require special processing techniques, such as the high-temperature firing of glass or the casting of metals, the production equipment for PET cups requires less investment and has lower maintenance costs. This means that companies can make smaller initial investments in fixed assets and operate with lower costs when producing PET cups, which helps them reduce product prices and enhance market competitiveness.
4.1.2, cost performance analysis
Considering the price and performance of PET cups, their cost-effectiveness is particularly prominent. Compared to glass cups, PET cups are more affordable. For the same volume and quality, PET cups cost only one-third to one-half as much as glass cups. PET cups excel in weight and impact resistance. Glass cups are heavier, making them less convenient for transportation and use, and they are more prone to breaking. In contrast, PET cups are lighter, more resistant to impact, and less likely to break, better meeting consumer needs. In food delivery services, PET cups can reduce transportation costs and minimize the risk of damage, offering convenience to both merchants and consumers.
Compared to paper cups, PET cups, while slightly more expensive, offer significant performance advantages. The costs of paper cups mainly include paper, printing, and processing expenses. Due to their poor water and moisture resistance, paper cups often require lamination, which increases production costs. In contrast, PET cups provide excellent water and moisture resistance, maintaining their shape and performance over time. When holding liquid beverages, paper cups are prone to deformation and leakage, whereas PET cups effectively prevent these issues, offering a better user experience. Additionally, PET cups are more recyclable than paper cups, making them more environmentally friendly and sustainable in the long run, thus offering a higher cost-performance ratio.
In terms of meeting consumer needs, PET cups have become the top choice for many consumers due to their moderate price and excellent performance. Their high transparency highlights the color and quality of beverages, stimulating consumer interest. The lightweight design makes them easy to carry and use. The excellent sealing ensures the freshness and taste of the beverages. In retail outlets such as supermarkets and convenience stores, beverages packaged in PET cups consistently rank among the top sellers, highlighting their popularity and cost-effectiveness in the market.
4.2 Environmental advantages
4.2.1 Recyclability and recycling
PET materials are highly recyclable, making them significant in environmental protection. PET cups can be recycled through various methods after use. Currently, the most common recycling methods are mechanical and chemical recycling. Mechanical recycling involves cleaning, crushing, and granulating discarded PET cups, which are then processed into PET pellets for the production of new PET products. This method is relatively simple and cost-effective, effectively reducing the need for new raw materials. In developed countries like Germany and Japan, a comprehensive PET mechanical recycling system has been established, achieving a recycling rate of over 80% for discarded PET cups.
Chemical recycling involves breaking down discarded PET cups into their original monomers or oligomers through chemical reactions, and then re-synthesizing them into new PET. This method ensures high-quality recycling of PET, with the recycled PET having performance similar to that of virgin PET, making it suitable for producing products with stringent quality requirements. Although chemical recycling technology is relatively complex and costly, its application prospects are expanding due to ongoing technological advancements. Some companies have already adopted this technology to convert discarded PET cups into high-quality recycled PET, which is used in areas such as food packaging.
The recycling of PET cups plays a crucial role in reducing plastic waste and environmental pollution. According to statistics, hundreds of billions of PET cups are recycled globally each year, equivalent to saving millions of tons of plastic waste from landfills and incineration. This not only conserves land resources but also reduces the harmful emissions from burning plastic waste, positively impacting environmental protection. Recycling PET cups also saves energy and resources, reducing dependence on fossil fuels like oil. Producing virgin PET requires significant oil consumption, whereas recycling PET cups can reduce oil extraction, lower energy consumption, and align with the principles of sustainable development.
4.2.2 Comparison of environmental friendliness
When compared to other non-biodegradable plastic cups and disposable paper cups, PET cups have a more significant environmental advantage. Compared to traditional non-biodegradable plastics like polyethylene (PE) and polypropylene (PP), although both are plastics, PET has better recyclability and biodegradability. In the natural environment, PE and PP plastics take hundreds or even thousands of years to fully degrade. However, under specific conditions such as high temperature, high humidity, and microbial action, PET degrades relatively quickly, typically within a few decades. The recycling technology for PET is more advanced, effectively reducing its environmental impact.
Compared to disposable paper cups, PET cups offer certain environmental advantages. While disposable paper cups are often seen as a relatively eco-friendly option, their production process consumes a significant amount of wood resources. According to statistics, producing one disposable paper cup requires about 10 grams of wood fiber, and the extensive use of disposable paper cups can severely damage forest resources. The production of paper cups also consumes a substantial amount of water and energy, and generates pollutants such as wastewater and exhaust gas during the manufacturing process. In contrast, the raw materials for PET cups primarily come from petrochemical products, which do not depend on wood resources, and the energy consumption and pollutant emissions during production are relatively low. Although PET cups are not biodegradable, they can be recycled effectively, promoting resource recycling and reducing environmental impact. From the perspective of contributing to sustainable development, the recyclable and reusable nature of PET cups helps promote the circular economy, reduce resource waste, lower environmental pressure, and contribute positively to achieving sustainable development goals.
4.3 Performance advantages
4.3.1 Comparison with other common plastic cup materials
Among the common plastic cup materials, PET cups offer unique performance advantages over PP (polypropylene), PS (polystyrene), and PC (polycarbonate). In terms of transparency, PET cups excel, with a light transmittance of over 85%, significantly higher than PP and PS. PP cups are typically semi-transparent with lower transparency, while PS cups, though somewhat transparent, lack the glossiness and clarity of PET cups. When it comes to showcasing the color and quality of beverages, PET cups provide a superior visual effect, enhancing the product’s appeal. In the packaging of high-end fruit juices, the high transparency of PET cups highlights the vibrant colors and purity of the juice, effectively attracting consumers’ purchasing interest.
In terms of hardness, PET cups are more durable and maintain their shape well, making them less prone to deformation. Compared to PP cups, PET cups can better maintain their integrity when subjected to external pressure. PP cups, on the other hand, are relatively softer and more likely to deform under significant force, which can affect their performance. During transportation and storage, PET cups provide better protection for the contents, reducing the risk of damage. For beverages that require long-distance transport, the high hardness of PET cups ensures safe delivery to their destination.
In terms of heat resistance, although the heat resistance of PET cups is generally around 70℃, which is slightly lower than PP (which can withstand temperatures up to 110-120℃) and PC (which can withstand higher temperatures), the heat resistance of 70℃ is sufficient for most beverage use scenarios. At room temperature, PET cups can hold a variety of beverages stably. In cold environments, the cold resistance of PET cups ensures they remain functional without cracking or other issues. Compared to PC cups, PET cups do not contain harmful substances like BPA, making them safer and more suitable for food and beverage packaging.
In terms of chemical stability, PET cups exhibit good resistance to weak acids and organic solvents. Compared to PS cups, PET cups are less likely to undergo chemical reactions when exposed to acidic beverages or products containing small amounts of organic solvents, thus maintaining the integrity of the packaging. PS cups, on the other hand, tend to swell and crack when exposed to certain chemicals, which limits their application. The chemical stability of PET cups makes them suitable for a variety of chemical environments, leading to their widespread use in the food and cosmetics industries.
4.3.2 Unique performance meets specific requirements
The high transparency and excellent gas barrier properties of PET cups make them ideal for specific needs such as beverage displays and carbonated drink packaging. In beverage displays, the high transparency of PET cups allows consumers to clearly see the color, state, and quality of the drinks inside, enhancing the product’s visual appeal. In milk tea shops, consumers can see the rich ingredients like pearls, coconut flakes, and sweet potatoes, as well as the smooth texture of the milk tea through the PET cups, significantly boosting the product’s appeal. Some high-end coffee brands also use PET cups to package their coffee, showcasing its rich color and abundant oils, thus enhancing the product’s quality.
For carbonated beverages, the excellent gas barrier properties of PET cups effectively prevent carbon dioxide from escaping, preserving the ‘carbonation’ and taste of the drink. Carbon dioxide in carbonated beverages is crucial for their unique taste and fizziness, and the gas barrier properties of PET cups ensure that carbon dioxide remains in the beverage for a long time. Studies show that at room temperature, carbonated beverages packaged in PET cups can maintain a low loss rate of carbon dioxide within the shelf life, typically not exceeding 15%, ensuring consumers enjoy a taste experience similar to when the drink was freshly produced. Compared with other packaging materials, such as glass bottles, which also have good gas barrier properties but are heavy and fragile, and plastic bottles (such as PP bottles), which have relatively poor gas barrier properties and cannot effectively preserve the ‘carbonation’ of carbonated beverages, the unique performance of PET cups makes them irreplaceable in the packaging of carbonated beverages.
5. Challenges and countermeasures faced by PET cup application
5.1 Challenges
5.1.1, heat resistance limit
PET cups have relatively low heat resistance, typically with a maximum temperature tolerance of only 70℃. This characteristic imposes numerous limitations in practical applications. When PET cups are filled with hot beverages, they are prone to deformation. For instance, freshly brewed coffee typically ranges from 80℃ to 90℃, far exceeding the heat resistance limit of PET cups. Pouring hot coffee into a PET cup can cause it to soften and deform within a short time, severely impacting its usability and potentially leading to leaks, causing inconvenience and safety hazards for users. High temperatures can also trigger chemical changes in PET cups. Under high-temperature conditions, additives in PET, such as antioxidants and plasticizers, may decompose or migrate. These changes can result in the release of harmful chemicals like bisphenol A (BPA) into the cup. Long-term exposure to these harmful substances can adversely affect the human endocrine and reproductive systems, posing a threat to health.
The heat resistance limitations of PET cups significantly restrict their application. In the tea industry, teas like Oolong and Pu’er, which require high-temperature brewing, typically need water temperatures above 90℃, making PET cups unsuitable for packaging these teas. In the coffee industry, consumers who value high-quality coffee prefer freshly brewed, hot coffee. The heat resistance of PET cups is insufficient, making them less appealing to this consumer group. In industrial and medical settings where high-temperature liquids or reagents are required, the heat resistance issues of PET cups also make them unsuitable.
5.1.2 Single-use issues
Currently, most PET cups on the market are disposable, leading to significant resource waste and environmental pressure. A large number of PET cups are discarded after a single use, causing severe resource depletion. The production of PET requires a substantial amount of fossil fuels, such as oil, and the widespread use of disposable PET cups accelerates the consumption of these non-renewable resources. According to statistics, the amount of oil used annually for producing PET cups is considerable. Reducing the use of disposable PET cups would significantly conserve oil resources and reduce dependence on fossil fuels.
The massive disposal of disposable PET cups also imposes a heavy burden on the environment. PET cups are difficult to degrade in natural environments and take hundreds of years or even longer to fully decompose. The accumulation of these discarded cups in landfills consumes significant land resources. These cups can also enter natural water bodies, such as oceans and rivers, through various means, posing a threat to aquatic life. Some marine animals may ingest these discarded cups, leading to digestive blockages and even death. As consumer environmental awareness continues to rise, there is growing skepticism and resistance towards the use of disposable PET cups. Consumers are increasingly opting for eco-friendly, reusable cups to minimize their environmental impact. This trend puts pressure on the market for PET cups, particularly in regions and among consumer groups with high environmental standards, where the market share of disposable PET cups is gradually shrinking.
5.1.3 Uneven quality
The quality of PET cups in the market varies widely, with some substandard products posing safety risks to consumers and damaging the industry’s reputation. Some unscrupulous merchants cut costs by using inferior raw materials for PET cup production, which may not meet food safety standards and contain harmful substances. When these substandard PET cups are used for beverages, harmful substances can migrate into the drinks, potentially harming consumers’ health. Some substandard PET cups may contain excessive levels of heavy metals, such as lead and mercury, which can cause heavy metal poisoning over time, affecting the nervous system and immune system.
Low-quality PET cups also have physical defects. They lack sufficient strength and hardness, making them prone to breaking or deforming, which fails to effectively protect the items inside. During transportation and storage, these cups can easily break due to minor impacts or squeezes, leading to leaks of beverages. This not only results in economic losses but also pollutes the environment. The presence of such substandard products severely damages the market reputation of PET cups, causing consumers to doubt their quality and trust in them. This is highly detrimental to the industry’s development, hindering its healthy growth and affecting the market share and economic benefits of legitimate companies.
5.2 Response strategies
5.2.1 Material modification and technical innovation
To address the issue of insufficient heat resistance in PET cups, researchers have focused on enhancing their thermal performance through material modification. A common approach is to incorporate reinforcing materials, such as glass fibers. Blending glass fibers with PET resin can significantly increase the heat deflection temperature of PET. The glass fiber content typically ranges from 10% to 50%, with higher content leading to better reinforcement. During the blending process, adding an appropriate coupling agent can enhance the interfacial bonding between glass fibers and PET resin, further improving the material’s performance. After this modification, the heat resistance of the PET cups can be increased to over 120℃, meeting the requirements for heat-resistant beverage packaging.
Copolymer modification is also an effective method to enhance the heat resistance of PET cups. By copolymerizing with other monomers, the molecular structure of PET can be altered, thereby increasing its heat deflection temperature. Commonly used copolymer monomers include isophthalic acid and naphthalene dicarboxylic acid, with the copolymer monomer content typically ranging from 5% to 30%. To ensure the copolymerization reaction proceeds smoothly, it is essential to select appropriate polymerization processes and catalysts. After copolymer modification, PET cups not only gain improved heat resistance but may also exhibit enhanced chemical stability and mechanical properties.
In the exploration of innovative technologies for reusable PET cups, some achievements have been made. Some companies have developed PET cups with special structural designs, making them more durable and easier to clean and reuse. A foldable PET cup can be folded when not in use, making it convenient to store and carry, while maintaining good stability during use. This design not only enhances the cup’s practicality but also reduces resource waste, aligning with environmental protection principles. Additionally, research is underway to develop new types of PET materials with enhanced antibacterial properties, which can effectively prevent bacterial growth during repeated use, ensuring user health.
5.2.2 Strengthen the construction of recycling system
Strengthening the PET cup recycling system is crucial for addressing environmental issues caused by single-use cups. Establishing a comprehensive recycling network is a key step. The government can encourage and support businesses to set up PET cup recycling stations in public places such as communities, schools, and shopping malls, making it easier for consumers to dispose of their used PET cups. Some cities have already started pilot programs to implement waste sorting systems, classifying PET cups as recyclable materials. This approach can effectively increase the recycling rate of PET cups. Additionally, professional recycling and transportation teams can be established to regularly transport used PET cups from recycling points to processing centers, ensuring efficient recycling operations.
Improving the recycling rate is also a key objective of the recycling system. Currently, PET cups are mainly recycled through mechanical and chemical methods. Mechanical recycling involves cleaning, crushing, and granulating waste PET cups, which are then processed into PET pellets for new products. To enhance the efficiency and quality of mechanical recycling, advanced equipment and technologies can be introduced. Automated cleaning systems can more thoroughly remove contaminants from the surface of PET cups, while high-precision crushing and granulation equipment ensures the production of more consistent PET pellets. Chemical recycling uses chemical reactions to break down waste PET cups into their original monomers or oligomers, which are then recombined to form new PET. Although this process is more complex and costly, it ensures high-quality PET recycling, with the recycled PET having performance similar to that of virgin PET. Increasing investment in research and development for chemical recycling technology and reducing costs will help improve the recycling rate of PET cups.
5.2.3 Improve quality supervision standards
Improving the quality supervision standards for PET cups is essential to ensure consumer safety and maintain the industry’s reputation. Establishing stringent production standards is fundamental. Relevant departments should clearly define the raw material standards used in the production of PET cups, ensuring that these materials meet food safety and environmental protection requirements. Detailed regulations should be set for the purity of PET resin, the types and quantities of additives, etc. Production process standards must be standardized, requiring companies to strictly control temperature, pressure, and other process parameters during production to ensure product quality stability. Strict product quality inspection standards should be established, with comprehensive testing of the physical, chemical, and hygiene properties of PET cups.
Strengthening market supervision is crucial for ensuring the effective enforcement of quality standards. Regulatory authorities should increase the frequency and intensity of inspections on PET cup manufacturers and sales markets. Regular on-site inspections should be conducted to check if the production equipment and processes meet the required standards, and if raw material procurement complies with regulations. Random sampling tests should be carried out on PET cups in the market to ensure they meet quality standards. Products that do not meet quality standards must be legally investigated, and companies ordered to rectify or halt production for reorganization, with severe penalties for non-compliant enterprises. Efforts should also be made to enhance public awareness and education regarding PET cup quality, improving consumers’ quality consciousness and ability to discern. By issuing consumer tips and organizing quality promotion activities, consumers should be informed how to select qualified PET cups, thereby enhancing their awareness of avoiding inferior products.
6. Conclusion and Prospect
6.1 Research Summary
This study makes a comprehensive and in-depth analysis of PET cups, from its characteristics, application fields to advantages, as well as the challenges and coping strategies.
In terms of characteristics, PET cups feature a unique chemical structure formed by the polymerization of terephthalic acid and ethylene glycol. This structure endows them with a range of excellent physical properties. They are lightweight and easy to carry and transport due to their low density; they maintain a stable shape thanks to their high hardness; and they have extremely high transparency, with a light transmittance of over 85%, allowing for a clear view of the contents. Chemically, PET cups are resistant to weak acids and organic solvents but are not tolerant of hot water and are prone to hydrolysis in alkaline environments. Thermally, they can withstand temperatures up to 70℃, but exceeding this temperature can cause deformation and the release of harmful substances. In terms of cold resistance, they can be used normally in temperatures ranging from-20℃ to 0℃, although low temperatures can increase the cup’s brittleness and hardness. In terms of barrier properties, PET cups effectively block oxygen, carbon dioxide, and water vapor, thereby extending the shelf life of beverages and maintaining their taste and quality.
PET cups have a wide range of applications, particularly in the beverage industry. In the tea and coffee sectors, their high transparency, lightness, and impact resistance meet consumers ‘needs for aesthetics, portability, and safety. Whether it’s takeout milk tea from milk tea shops or takeout coffee from coffee shops, PET cups are the preferred choice. For juice and carbonated drink packaging, the excellent gas barrier properties of PET cups help maintain the freshness of juices and the ‘carbonation’ of carbonated drinks. Their chemical stability also allows them to withstand the acidic environments of these beverages. In other food packaging areas, such as snack packaging, PET cups can prevent moisture and oxidation, extending the shelf life of snacks. As edible ice cups, they perform stably in low-temperature environments, meet food safety standards, and are aesthetically pleasing, making them popular among consumers. Additionally, PET cups have potential applications in the medical field and industrial sample containers, but when used in the medical field, they must meet higher standards for sterility and barrier properties.
The advantages of PET cups are significant. In terms of cost-effectiveness, they offer low raw material costs and mature production processes, making them highly cost-effective. Compared to glass and paper cups, PET cups are more competitive in both price and performance. They also have notable environmental benefits, being highly recyclable through mechanical and chemical methods, which helps reduce plastic waste and environmental pollution. Compared to other non-biodegradable plastic cups and disposable paper cups, PET cups are more environmentally friendly. In terms of performance, PET cups outperform common plastic cup materials like PP, PS, and PC in transparency, hardness, and chemical stability. Their high transparency and excellent gas barrier properties make them ideal for specific applications such as beverage display and carbonated drink packaging.
PET cups face several challenges in their application. Their heat resistance limits them from holding hot beverages, and they are prone to deformation and the release of harmful substances, which restricts their use in high-temperature brewing scenarios. The issue of single-use cups leads to resource waste and environmental pressure, with a large number of discarded PET cups occupying land resources and posing risks to natural water bodies and wildlife. As consumer environmental awareness grows, the market share of PET cups is being squeezed. The quality of PET cups on the market varies widely, with some inferior products using substandard materials, posing safety hazards and physical defects, which negatively impact the industry’s reputation and consumer trust. To address these challenges, we propose strategies including improving heat resistance through material modification and technological innovation, developing reusable cups, enhancing the recycling system to increase recycling rates and utilization, and refining quality supervision standards to ensure product quality and consumer safety.
6.2 Future Development Trend Outlook
Looking ahead, PET cups are poised to achieve new breakthroughs and developments in multiple areas. In terms of material innovation, as technology advances, more high-performance PET modified materials will be developed. By using techniques such as copolymerization and blending, the heat resistance, cold resistance, and barrier properties of PET cups can be further enhanced, making them suitable for a wider range of applications. Developing PET materials with a heat resistance exceeding 100℃ will meet the packaging needs for hot beverages like coffee and tea, expanding the application of PET cups in the beverage industry. Additionally, developing PET materials with superior antibacterial properties for food and medical packaging will effectively prevent bacterial growth, ensuring product safety and quality.
In terms of expanding application areas, PET cups will continue to open up new market opportunities. As emerging industries such as biopharmaceuticals and new energy grow, the demand for packaging materials is increasing. Thanks to their superior performance, PET cups are expected to find applications in these sectors. In the biopharmaceutical industry, PET cups can be used to store biological agents and vaccines, ensuring the quality and efficacy of medicines with their chemical stability and barrier properties. In the new energy sector, PET cups can serve as packaging for electrolytes and energy storage materials, meeting the specific requirements of these materials. The use of PET cups in daily life will also become more diverse, such as in travel and outdoor settings, where special-function PET cups, like those with thermal insulation and filtration features, can be developed to meet consumers’ personalized needs.
Improving environmental performance will be a key direction for the future development of PET cups. As global attention to environmental protection continues to grow, the recyclability and sustainability of PET cups will become crucial for industry growth. In the future, efforts will focus on refining the recycling system for PET cups, enhancing recycling efficiency, and promoting resource recycling. Research and development in PET cup recycling technology will be intensified to reduce costs and improve quality, making recycled PET materials as close to virgin PET materials as possible. The development of biodegradable PET materials will also be promoted to minimize their environmental impact and reduce their presence in the natural environment.
To promote the healthy development of the industry, companies should increase their investment in material research and development and technological innovation, continuously launching high-performance, eco-friendly PET cup products. The government should enhance policy guidance and support, establish relevant standards and regulations to regulate industry development, and encourage companies to engage in environmental protection and innovation activities. Consumers should also raise their environmental awareness, actively participate in the recycling and reuse of PET cups, and work together to advance the PET cup industry towards sustainable development.
