Recycling Household Post-Consumer Multi-Layered Plastic (MLP) Waste
What is Multi-Layered Plastics (MLP)?
Most plastics used in households are multi-layered plastics (MLPs). Open your pantry, and you’ll likely see food items packed in plastic: chips, candy, granola bars, rice, and even meat or fish are often wrapped using MLPs. Beyond food, soaps, shampoos, and reusable beauty products also use MLPs. Why?
MLPs are chosen for packaging because they combine properties that effectively protect products from external elements such as oxygen, moisture, and light. However, have you ever wondered what happens to these plastics after you use them? You might have heard how plastics contribute to environmental pollution. Multi-layered plastics are significant contributors to this problem because they are hard to recycle due to their complex structure. However, not all MLPs fall into this category—some can be recycled.
Types of Multi-Layered Plastics (MLP)
Multi-layered plastics are composed of multiple polymer layers, designed to combine the unique properties of each material. Here are some common types of MLPs:
1. Flexible Multi-Layer Plastics
Flexible MLPs consist of multiple layers of different materials, providing protection for food and other products. Examples include:
Food storage bags
Chips bags
Ramen packages
Potting soil, fertilizer, and cement sacks
Produce netting
Common compositions:
Polyethylene (PE) + Polypropylene (PP): Used in food packaging for excellent barrier properties and flexibility.
Polyethylene (PE) + Ethylene Vinyl Alcohol (EVOH): Common in vacuum-sealed food bags for superior oxygen barrier protection.
Polyethylene (PE) + Polyamide (PA): Found in high-barrier packaging like cheese or meat pouches.
2. Rigid Multi-Layer Plastics
Rigid MLPs are commonly used in applications like food packaging, cosmetics, and industrial products. Examples include:
Tetra packs for milk and juice
Pharmaceutical packaging
Toiletries and cosmetics containers
Common compositions:
Polypropylene (PP) + Polystyrene (PS): Used for containers requiring stiffness and transparency.
Polycarbonate (PC) + Acrylonitrile Butadiene Styrene (ABS): Found in automotive parts, electronics, and appliances for durability and heat resistance.
Polyethylene Terephthalate (PET) + Polyethylene (PE): Used in beverage bottles and food trays for strength and barrier properties.
3. Multi-Layer Films
Multi-layer films are composed of materials like plastic, aluminum, or paper. They are used in food packaging, construction, and art. Examples include:
PET + Aluminum Foil + PE: Provides exceptional barriers against light, moisture, and gases.
Biaxially Oriented Polypropylene (BOPP) + Polyethylene (PE): Used in snack packaging for clarity, strength, and barrier properties.
4. Specialized Multi-Layer Plastics
Polyvinyl Chloride (PVC) + Acrylonitrile Styrene Acrylate (ASA): Used in outdoor applications like window frames due to weather resistance.
EVOH + Polyamide (PA) + Polyethylene (PE): Utilized in pharmaceutical and medical packaging for high oxygen and moisture barriers.
5. Recycled Multi-Layer Plastics
Post-Consumer Recycled (PCR) Layers: Combines recycled content with virgin plastics for sustainable packaging solutions.
Mixed Waste Plastics (MWP): Blended layers from various plastic types, often used in non-critical applications.
Recycling Multi-Layered Plastics
Recycling Multi-Layered Plastics is challenging due to their complex structure. Many end up in landfills or pollute rivers and oceans. Despite their environmental impact, MLPs remain popular in the FMCG industry because they are economical, durable, and effective in protecting products. MLPs also offer branding and marketing opportunities.
Some organizations focus on source segregation and collection of MLP waste for recycling. Others remove MLP waste from landfills and oceans. However, traditional recycling methods are not effective for all types of MLPs, and some are incinerated, causing air pollution.
Household Multi-Layer Plastic and Sand Extrusion Process
Recent advancements in polymer sand extrusion, also known as plastic sand extrusion, provide a way to recycle a portion of MLP waste. This process converts MLPs into sustainable products like paving blocks, tiles, and planks. It involves using a specialized heating and melting system (plastic sand extruder) to process the plastic sand composite, which are then molded into functional products.
By adopting such technologies and improving waste segregation practices, we can turn multi-layered plastic waste into valuable resources, reducing its environmental impact.
