6. Polystyrene (PS)
- Types: It is divided into foamed and unfoamed categories. Foamed refers to the commonly seen foam plastic lunch boxes. Unfoamed refers to items like yogurt plastic bottle and the cap. Unfoamed PS shows white marks when lightly bent and can usually be torn apart by hand.
- Commonly Used For: Ice cream containers, fast food boxes, cheap transparent products, foam plastics, CD cases, water cups, and thermal insulation material layers.
- Advantages: It has excellent transparency and heat resistance, and is often used to hold high-temperature food, such as bowled instant noodles (though paper containers are mostly used now). It also has good cold resistance, making it popular for various shaved ice containers.
- Warnings: If the temperature is too high, it will release harmful substances. It cannot be put into a microwave oven for heating, and it should not be used to hold piping hot food. At the same time, it cannot hold strong acidic (such as fruit juice) and strong alkaline substances. If PS encounters strong acidic or alkaline substances, it will produce harmful substances. Be careful when using PS utensils; do not fill them with acidic or alkaline foods. Do not use fast food boxes to pack piping hot food, and do not use a microwave oven to heat bowled instant noodles.
- Safety Risks: Additionally, polystyrene is flammable, especially foamed PS. Burning generates a large amount of toxic gases. In some high-rise building fire accidents, because the insulation layer material used widely available PS foam boards, the large amount of heavy smoke and toxic gases generated after catching fire became the main cause of heavy casualties.
7. Polycarbonate (PC)
- Introduction: It is synthesized using Bisphenol A and diphenyl carbonate as raw materials , and is commonly used to manufacture water kettles, water cups, feeding bottles, etc. During the manufacturing process of PC, the raw material Bisphenol A should completely become part of the plastic structural component and should not be released during use. However, substandard products cannot achieve this, and a small part of Bisphenol A that fails to completely convert into the plastic will be released into food when heated, which is harmful to children and fetuses. (The 2011 PC feeding bottle incident was triggered by this) . It is currently the most common material for water cups; many department stores and car manufacturers use water cups made of this material as giveaways.
- Commonly Used For: In daily life, it is often used for transparent water cups, feeding bottles, drinking water buckets, CD substrates, lenses, and lamp covers.
- Advantages: It features good light transmission, excellent heat resistance, impact resistance, and resistance to weak acids, weak bases, and neutral oils. Compared to a heavy glass bottle, it is much lighter and more impact-resistant.
- Warnings: It has poor UV resistance and weatherability ; the surface is not wear-resistant and is easily scratched ; it is not resistant to strong bases.
8. Polyamide (PA)
- Introduction: Mentioning the other name of polyamide: Nylon—everyone must be familiar with it. The polyamide family is very powerful and has many varieties, all of which possess excellent physical and chemical properties. This is also the reason why PA is widely used in the electronic appliance and automotive industries. In daily life, nylon ropes and nylon socks are also common items. Spun PA fiber is called chinlon, which is used for fishing lines, fishing nets, ropes, and conveyor belts.
- Commonly Used For: Nylon ropes, nylon socks, fishing lines, fishing nets, ropes, conveyor belts, etc.
- Advantages: Nylon is non-toxic and has good heat resistance. Especially because it is heat-resistant and not easily deformed, it can even be used in the manufacture of engine components.
- Warnings: Nylon has poor ventilation and breathability, and it easily generates static electricity.
9. ABS Resin
- Introduction: There are many types of ABS, which are widely used in various appliance casings, office supply components, safety helmets, doors, windows, and pipelines. In industry, ABS is commonly used for the blending modification of other plastics.
- Advantages: ABS has many advantages, but it still possesses the common characteristic of plastics: it is not heat-resistant.
- Usage Warnings: ABS is non-toxic, but it is mostly used for structural materials. Its application in daily utensil packaging is rare.
10. Blends (Alloys)
- Introduction: Since a single plastic can hardly meet complex usage requirements, the plastic industry often mixes different plastics together to make plastic alloys. This can leverage the advantages of different materials while saving the cost of developing new materials.
- Main Applications: Plastic alloys are widely used in various structural materials. For example, mobile phone cases are mostly PC-ABS alloys ; some drainage pipes are made into alloys of two types of PE to meet performance and processing needs, which is called bimodal polyethylene.
- Usage Warnings: Although it combines the advantages of multiple plastics, the material is ultimately still plastic, and heat resistance remains the biggest disadvantage. However, in practical applications, most products will not come into contact with high temperatures. As long as you pay attention to the application environment, plastic is absolutely a cheap and applicable good material.