Different ways the check the contents of recycled material

Way to check the recycled content:

• Checking the Certificate of Analysis from your supplier
• Check recycling codes and labels on the material
• Request test reports that show recycled percentage
• Get documentation showing input materials used in production

Certificate of Analysis (CoA): is a  document that confirms a product's quality by listing the actual test results for different properties (like physical, chemical, and performance characteristics) of a specific batch or lot of material. It serves as quality evidence that the product meets the required specifications.

Detailed analysis method:

Laboratory testing:

Thermal analysis:

• DSC (Differential Scanning Calorimetry)
• Measures melting points and crystallization
• Recycled material shows different thermal patterns
• Can estimate percentages based on curve variations
• Accuracy around ±5-10%

Differential scanning calorimetry (DSC): is a thermal analysis technique that measures how a material's heat capacity changes with temperature. It works by heating a sample and a reference material and measuring the difference in heat flow between them.

It is the material's "thermal fingerprint". It shows how the material behaves when heated or cooled, which is crucial for understanding its properties and processing conditions.

Spectroscopy methods:

They are techniques that study how matter interacts with electromagnetic radiation (like light) to identify and analyze materials. Different types of spectroscopy use different types of light or energy to reveal specific information about materials.

• FTIR (Fourier Transform Infrared)
• Shows chemical composition changes
• Identifies degradation markers
• Can detect additive variations
• More accurate for higher percentages

Fourier Transform Infrared (FTIR): is a  technique that identifies chemical compounds in materials by measuring how they absorb infrared light at different wavelengths. It creates a unique "fingerprint" spectrum that shows the molecular structure of the material.
It is a molecular "photograph" that reveals what chemical compounds are present in your material.

Advanced methods:

• NMR (Nuclear Magnetic Resonance)
• Most accurate but expensive
• Shows molecular structure differences
• Can detect subtle variations
• Accuracy up to ±2%

Nuclear Magnetic Resonance (NMR): is a technique that uses powerful magnets and radio waves to analyze the molecular structure of materials by looking at how atomic nuclei (usually hydrogen) respond to magnetic fields. It reveals detailed information about the molecule arrangement and the chemical composition of materials.

Documentation methods:

Mass balance calculation:

• Track virgin material input
• Track recycled material input
• Calculate ratio from production records
• Document material flows

Supply chain verification:

• Supplier declarations
• Processing records
• Material certifications
• Third-party audits

Quality control methods:

Physical properties testing:

• Melt flow index
• Density measurements
• Color consistency
• Mechanical properties

Melt Flow Index (MFI): is a measurement of how easily melted plastic flows, determined by the amount of material that flows through a standard die (opening) under specified temperature and pressure conditions within a set time period. It's expressed in grams per 10 minutes.

Visual inspection:

• Color variations
• Texture differences
• Pellet consistency
• Contamination levels

Limitations:

Technical:

• No perfect single test exists
• Methods vary by plastic type
• Results can be affected by additives

Practical:

• Cost of testing are high
• Time requirements should be taken into account
• Equipment availability
• Expertise needed for the techniciens performing the tests