Recycled Plastic : Identifying recycled plastic content

Below is a simple and detailed explanations for identifying recycled plastic content.

Recycled plastic content can be verified through:

• Certification labels showing recycled percentage
• Documentation from material suppliers
• Chemical analysis in a lab
• Resin identification codes (though these alone don't prove recycled content)

Resin identification codes (RIC) are numbers inside a triangle of arrows on plastic products that identify the type of plastic material used. They range from 1 to 7: 1 - PET (water bottles) 2 - HDPE (milk jugs) 3 - PVC (pipes) 4 - LDPE (bags) 5 - PP (bottle caps) 6 - PS (foam cups) 7 - OTHER (mixed/specialty plastics)

In-depth explanation:

Chemical Testing Methods:

• Differential Scanning Calorimetry (DSC) - Shows thermal history differences between virgin and recycled plastics
• Melt Flow Index (MFI) - Typically higher in recycled materials due to polymer chain breakdown
• Fourier Transform Infrared Spectroscopy (FTIR) - Can detect contaminants and degradation markers common in recycled materials
• Gas Chromatography/Mass Spectrometry (GC/MS) - Identifies trace compounds indicating previous use

Physical Testing Methods:

• Microscopy analysis used to detect inconsistencies in structure
• Color variation analysis
• Density testing tests recycled materials often have slightly different densities
• Mechanical property testing used for tensile strength, impact resistance

Tensile strength is the maximum stress a material (like plastic) can withstand while being pulled before breaking. It's how much pulling force it takes to break something.

Documentation Verification:

• Chain of custody documentation is the documented trail showing who has handled or possessed materials/products at every step from source to final destination
• Supplier certificates of analysis
• Third-party certification (e.g., UL Environmental Claim Validation)
• Mass balance accounting for recycled content tracks all materials flowing in and out of a production system to ensure everything is accounted for.

Standards and Certification:

• ISO 14021 for environmental claims
• EN 15343 for plastics recycling traceability
• Global Recycled Standard (GRS)
• Recycled Claim Standard (RCS)

Global recycled standard (GRS): A comprehensive certification that tracks and verifies recycled content through the entire supply chain, plus ensures environmental and social practices meet standards. It's like a complete "passport" for recycled materials.
Recycled claim standard (RCS): A simpler version that only focuses on tracking recycled material content through the supply chain. It is similar to GRS but without the environmental and social requirements.

Percentage Calculation Methods:

• Post-consumer recycled content percentage = (Weight of post-consumer material / Total weight) × 100
• Pre-consumer recycled content percentage = (Weight of pre-consumer material / Total weight) × 100
• Total recycled content = Post-consumer + Pre-consumer percentages

Post-consumer recycled material: Products that have been used by consumers and then recycled, for example water bottles from recycling bins, used plastic containers, or recycled packaging from homes.
Pre-consumer recycled meterial: the manufacturing waste that is recycled before reaching consumers, like factory cutoffs, rejected parts, or production excess.

Visual Indicators (though not definitive):

• Slight color variations
• Minor surface irregularities
• Inconsistent pellet size in raw material
• Presence of very small contaminants

Traceability Systems:

• Digital watermarking: Invisible codes embedded in plastic products that can be scanned to verify authenticity and track products.
• Blockchain tracking: Digital ledger system recording every transaction and movement of materials/products that can't be altered. 
• Mass blance approaches: Accounting system tracking materials entering and leaving a system to ensure all is accounted for. 
• Batch coding systems: Method of marking and tracking groups of products made at the same time under same conditions.