[GREEN MONDAY SERIES] #5: How are Plastics classified? What Are Their Properties?

We are living in a world where plastics are present everywhere, a testament to their convenience and utility. However, when plastics are misused - being used unnecessarily, discarded improperly without reuse, or not sorted for proper waste management, they become associated with negative perceptions. This mismanagement leads to the misconception that plastics themselves are inherently harmful to the environment and human health, rather than the way they are handled and disposed of.

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How Are Plastics Classified? What Are Their Properties?

Today, let's explore with Zeen to learn how to distinguish 7 different types of plastic!

Therefore, during this period, Zeen will guide you in understanding the properties of different types of plastics based on the Resin Identification Code (RIC). This will help you recognize plastics through:

• Their appearance

• Their common uses

• The appropriate temperature range for each type

By gaining this knowledge, you can distinguish among different types of plastics and use them correctly - ensuring both your health and contributing to waste reduction and environmental protection.

Plastic Type #1 (PET/PETE)

Full Name: Polyethylene Terephthalate

Common Examples: Most soft drink bottles, mineral water bottles, plastic food containers, and scratch-resistant coatings on film materials.

Characteristics:

• Being typically transparent, brittle, and prone to scratches.

• Being safe for food storage but should not be used for items above 70°C, as heat may cause deformation and potential health risks.

• Offering high resistance to CO₂ permeability.

• It should not be placed in the microwave or exposed directly to sunlight.

• Being certified as safe by the U.S. FDA and the European EFSA, PET does not contain Bisphenol-A (BPA) - a compound often linked to endocrine disruption and cancer concerns. In reality, the risk of BPA leaching from plastic products is extremely low.

Usage Recommendations:

• Whenever possible, avoid using PET plastics or single-use plastics. Instead, choose reusable water bottles and food containers to minimize waste.

• If you must use single-use plastic bottles, they can be safely reused by washing them thoroughly, avoiding exposure to temperatures above 70°C, and keeping them out of direct sunlight.

• When a PET plastic item is no longer reusable, dispose of it properly by placing it in designated recycling bins.

Plastic Type #2 (HDPE)

Full Name: High-Density Polyethylene

Common Examples: Hard plastic bottles, detergent containers, baby bottles, shampoo and body wash bottles, cosmetic packaging, fiber optic cables, underground electrical wires.

Characteristics:

• Being typically opaque, highly resistant to abrasion; hard HDPE plastics can scratch easily, while softer variants do not.

• A thermoplastic material that softens into a liquid at high temperatures for molding and solidifies upon cooling.

• Being known for its high density, durability, and flexibility, making it resistant to impact and high pressure.

• Being one of the safest plastics for food storage as it does not contain harmful substances like lead, mercury, or BPA.

• Being safe for use between -65°C and 85°C but should not be placed in the microwave and may crack when exposed to sudden temperature changes.

• Being highly resistant to water, moisture, and most cosmetic and chemical products, making it a preferred material for packaging cosmetics and hot/cold liquid containers.

• Absorbing and retaining oils, making it difficult to clean thoroughly. It is not recommended for storing oily or fatty foods as oils can permeate the material.

Usage Recommendations:

• Being suitable for food storage within the temperature range of -65°C to 85°C.

• Avoid using HDPE for storing oily or fatty foods due to its tendency to absorb oils, which makes cleaning difficult. Instead, consider PET (#1) for such uses.

• Being able to be safely reused multiple times, but must be washed regularly, similar to PET plastics.

• When no longer reusable, dispose of it properly in the appropriate recycling category.

Plastic Type #3 (V/PVC)

Full Name: Polyvinyl Chloride

Common Examples: Raincoats, water pipes, cable insulation, transparent plastic bags, food wrap, blood bags, IV tubes, certain medical instruments, and furniture.

Characteristics:

• Being lightweight, brittle, and rigid; often combined with additives to enhance flexibility and mechanical strength.

• While these additives are present in low and generally safe concentrations, prolonged or high-level exposure — particularly through food-contact items — has raised health concerns.

• Being highly resistant to weather conditions, making it ideal for water pipes and cable insulation.

• Being non-heat-resistant (melting point: 150–200°C), with a recommended usage range of 0°C to 80°C. Avoid using PVC food wrap (ivory or light yellow in color) in the microwave as heating can release harmful substances.

• Being naturally flame-retardant because of its chlorine content which originates from common salt used in PVC production.

• Being highly resistant to chemical reactions, remaining unaffected by many organic solvents and most inorganic chemicals.

• Being certified as safe by the U.S. FDA for use in food and pharmaceutical packaging as well as medical devices. However, incomplete or inefficient combustion of PVC can release toxic substances.

Plastic Type #4 (LDPE)

Full Name: Low-Density Polyethylene

Common Examples: Food containers, disposable plastic gloves, plastic bags, food packaging, shopping baskets, computer and phone accessories, laboratory equipment.

Characteristics:

• Being waxy texture, smooth to the touch, colorless, odorless, soft, lightweight, and highly flexible.

• A thermoplastic material known for high durability, excellent corrosion resistance, impact resistance, moisture resistance, and superior thermal and electrical insulation, making it easy to manufacture and process.

• Being recommended usage temperature range: -78°C to 100°C, with a melting point of 110°C.

• Having a lower density than HDPE (Plastic #2) with similar properties but lower durability, making it more prone to cracking or breaking.

• Should not be used in the microwave above the recommended temperature limits.

• Being chemically stable, making it safe for food packaging and suitable for multiple uses within the permitted temperature range.

Usage Recommendations:

• Being best suited for cold storage applications.

• Being able to be reused multiple times if properly cleaned.

• Always check and follow packaging labels to ensure proper use for each type of plastic.

• While LDPE plastics are technically recyclable, recycling facilities for this type are limited. Only transparent, flexible plastic bags are commonly collected for resale and recycling. Proper sorting and thorough cleaning of organic residues are essential before recycling.

Plastic Type #5 (PP)

Full Name: Polypropylene

Common Examples: Water bottles, food storage containers, toys, household items, straws, traffic signal covers.

Characteristics:

• Being a rigid thermoplastic material.

• Being naturally transparent white, odorless, tasteless, and non-toxic. However, it is often mixed with colorants to create more visually appealing consumer products.

• Having a smooth, glossy surface finish.

• Being highly resistant to water, gases, oxidation, moisture, and oils, making it ideal for use in containers, jars, cans, bottles, and packaging.

• Being able to withstand high temperatures with a thermal tolerance of 130°C to 170°C.

• Possessing high mechanical strength, ensuring durability.

• Being predominantly used for food-grade plastic products.

Usage Recommendations:

• Being safe for food storage within the temperature range of -15°C to 130°C.

• Being able to be used in microwaves for reheating food, but exposure should be limited to 2–3 minutes to ensure safety.

• Being able to be reused multiple times, provided it is thoroughly washed and used within the recommended temperature range.

• Being highly recyclable and often referred to as a "high-value plastic" since it can be melted and repurposed into various products. To prevent waste, ensure proper sorting and disposal at recycling facilities.

Plastic Type #6 (PS)

Full Name: Polystyrene

Types of PS Plastics:

• EPS (Expanded Polystyrene): Lightweight and foam-like, used for foam food containers and shock-absorbing packaging materials.

• HIPS (High-Impact Polystyrene): Hard and brittle, commonly used in motorcycle parts, TV casings, trays for confectionery, yogurt cups, disposable plates, bowls, and cups.

• GPPS (General-Purpose Polystyrene): Hard and transparent, used in wall clocks, electric meter housings, food trays, and premium cosmetic containers.

Characteristics:

• A thermoplastic material available in both rigid and foam-like forms, naturally colorless, odorless, and transparent. When burned, it produces an unstable flame.

• Soluble in organic solvents, making it unsuitable for storing acetone, kerosene, or essential oils.

• Hard, brittle, and lightweight, making it a preferred choice for many disposable and lightweight products.

• The U.S. FDA has approved PS for food-contact applications, though concerns exist regarding its stability at high temperatures.

Usage Recommendations:

• Avoid using PS plastics for hot liquids, oily foods, pickled items, vinegar, or any food above 70°C, as high temperatures can release monostyrene, which may harm the liver.

• Being able to be reused, but must be thoroughly washed and used within safe temperature limits.

• Technically recyclable; however, because of its low recycling value, only a few specialized facilities can process it. To minimize environmental impact, reduce single-use PS plastics and ensure proper sorting for potential recycling.

Plastic Type #7 (Other)

Common Types:

• PC (Polycarbonate): Commonly used for water bottles, baby bottles, food containers, and more. There has been debate regarding the safety of PCs, with concerns that it could cause cancer because of the presence of BPA. However, in 2014, the FDA published a report confirming that the exposure limit for BPA is 50 µg/kg (approximately 23 µg/lb) daily, concluding that BPA is safe at allowable levels. Consequently, products made from PC are labeled BPA-Free, ensuring they are free of the harmful substance.

• Tritan: Being known for its glass-like transparency and resistance to breaking, Tritan is often used for water bottles, food containers, drinking glasses, etc., offering safety for users.

Characteristics of Polycarbonate (PC):

• High Durability and Impact Resistance: Polycarbonate’s toughness makes it resistant to impact and breaking, ensuring reliability in applications requiring high performance.

• UV Protection: PC can be coated with anti-UV layers, offering protection from harmful ultraviolet rays, blocking 100% of UV radiation.

• Optical Properties: Because of its amorphous structure, PC exhibits excellent optical properties, with a refractive index of 1.584 (clear PC), comparable to lenses used in eyewear, which generally have a refractive index between 1.50 and 1.74.

• Chemical Resistance: PC is resistant to diluted acids, hydrocarbons, and alcohols; moderately resistant to oils and fats. However, it is highly susceptible to attack from alkaline substances, aromatic hydrocarbons, and halogens. Manufacturers recommend cleaning with non-alkaline cleaners to avoid damage.

• Heat Resistance: Polycarbonate has excellent thermal stability, maintaining structural integrity up to 135°C.

• Food Safety: PC is recognized as safe for food-contact applications, and is commonly used for baby bottles, reusable water bottles, sippy cups, and other food and drink containers. Despite BPA concerns, regulatory bodies like the FDA, European Food Safety Authority, and the UK Food Standards Agency have deemed PC safe for food contact, leading to the development of BPA-free polycarbonate alternatives in response to public health concerns.

Usage Recommendations:

• Avoid using Polycarbonate (PC) to store hot liquids or hot food.

• PC plastic is safe for use with food and drinks at normal temperatures, but should not be exposed to high heat.

• If you need to store hot items, consider Tritan or BPA-free versions.

• Polycarbonate is durable and can be reused multiple times; on the other hand, it must be thoroughly cleaned and used within safe temperature limits for each type (PC: < 80°C, Tritan: < 109°C).

• This plastic is recyclable and can be sold for scrap. Therefore, ensure that it is disposed of properly in the recycling bin.

This is all the information regarding the 7 different types of plastic. Zeen hopes that after this article, you will better understand the nature and the uses of each type of plastic in order to ensure safety for health while unharming the environment!

PLASTIC IS NOT AT FAULT; THE FAULT LIES IN OUR MISUSE!

Don’t forget to practice Green!

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