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Understanding Plastic Recycling

What Is Mechanical Recycling in Packaging?

Mechanical recycling is a process that physically collects, sorts, cleans and reprocesses plastic without intentionally breaking the polymer down into its basic chemical building blocks.

Quick Answer Mechanical recycling takes used plastic, separates it by material, cleans it, grinds or flakes it, and reprocesses it into recycled feedstock that can be used in suitable new products or packaging.

In rigid packaging, this is one of the primary pathways used to produce post-consumer recycled materials such as recycled PET and recycled HDPE.

The quality and possible uses of mechanically recycled material depend on the incoming material stream, contamination, sorting quality, processing conditions and the requirements of the next application.

How Mechanical Recycling Works What It Means for Packaging
Mechanical Recycling Image Placeholder Show used PET and HDPE rigid packaging moving through sorting, washing, grinding, recycled resin production and into a new packaging application.

The Fundamental Concept

What Does Mechanical Recycling Mean?

Mechanical recycling changes the physical form of plastic while retaining the polymer as plastic.

Used plastic packaging is collected and separated into material streams such as PET or HDPE. The material can then be cleaned, reduced into flakes or smaller pieces and processed into recycled feedstock.

That recycled material may then be used to manufacture suitable new products or packaging, depending on its quality and the requirements of the intended application.

Packaging Example

Example: Used HDPE Bottle to PCR Resin

A used HDPE bottle may be collected, sorted with other compatible HDPE material, washed, ground and reprocessed into recycled HDPE resin.

That recycled resin may then be blended or used at an appropriate percentage in a suitable new product or packaging application.

Key takeaway: Mechanical recycling physically reprocesses the plastic. It does not intentionally convert the polymer back into its original chemical building blocks.

The Recycling Process

How Does Mechanical Recycling Work?

The exact process varies by material and facility, but a simplified mechanical recycling pathway often includes the following stages.

1
Collection Used plastic enters an available recovery or collection system.
2
Sorting Materials are separated by resin, color or other characteristics.
3
Cleaning Product residue, labels and other contaminants are reduced or removed.
4
Grinding Plastic is physically reduced into flakes or smaller pieces.
5
Reprocessing Material is processed into usable recycled feedstock.
6
New Application Recycled material is used in a suitable new product or package.

Material Quality Matters

Why Is Sorting So Important in Mechanical Recycling?

Mechanical recycling works best when the incoming material stream is reasonably clean and compatible.

Different plastics have different properties and processing requirements. Mixing incompatible materials can affect the quality, appearance and performance of the recycled output.

Labels, closures, colors, additives, residual product and other materials can also influence sorting and recycled-material quality.

Sorting Image Placeholder Show PET and HDPE rigid containers on a material recovery or sorting line, with different resin streams being separated.

Rigid Packaging Examples

Which Rigid Packaging Materials Are Commonly Mechanically Recycled?

Actual collection and recycling availability varies by market and application, but several rigid-plastic resin streams are commonly associated with mechanical recycling.

PET

PET bottles and containers can enter mechanical recycling streams where appropriate collection, sorting and processing infrastructure exists.

HDPE

HDPE bottles and containers are another common rigid-plastic stream that may be mechanically processed into recycled material.

PP

Polypropylene packaging may also move through mechanical recycling systems where collection, sorting and viable processing pathways are available.

Understanding the Tradeoffs

What Are the Advantages and Limitations of Mechanical Recycling?

Potential Advantages

✓
Keeps recovered plastic material in productive use.
✓
Can produce recycled resin for suitable new applications.
✓
Supports demand for recovered PET, HDPE and other materials.
✓
Can reduce reliance on virgin resin when appropriate.
✓
Works with established recycling systems for certain materials.

Potential Limitations

✓
Requires effective collection and sorting.
✓
Contamination can affect recycled-material quality.
✓
Mixed or incompatible materials can create processing challenges.
✓
Repeated processing may affect some material properties.
✓
Not every recycled grade is suitable for every packaging application.

What Manufacturers Need to Understand

Not All Mechanically Recycled Resin Is the Same

Recycled resin quality can vary based on the source material, collection stream, contamination, sorting accuracy, processing technology and intended end use. Manufacturers should evaluate the actual resin grade and package performance rather than treating all PCR as interchangeable.

Source Material
Sorting Quality
Contamination
Processing History
Intended Application

A Common Question

Mechanical Recycling vs. Chemical Recycling: What’s the Difference?

Both terms describe approaches to processing plastic waste, but they work differently.

Question Mechanical Recycling Chemical Recycling
What happens to the plastic? Plastic is physically sorted, cleaned and reprocessed while the polymer remains substantially intact. Plastic is transformed using chemical or thermal processes into feedstocks, intermediates or other outputs.
Typical process Sorting, washing, grinding, melting and reprocessing. Process depends on the technology and may involve depolymerization, pyrolysis or other conversion routes.
Output Recycled flakes, pellets or resin suitable for certain applications. Chemical feedstocks or other outputs that may be used in further manufacturing processes.
Does one replace the other? Not necessarily. Different materials, waste streams, technologies and applications may require different recovery approaches.

Practical Packaging Decisions

What Should Manufacturers Consider When Using Mechanically Recycled Resin?

PCR Percentage

Determine the appropriate recycled-content level for the resin, package and application.

Product Compatibility

Confirm that the recycled resin and package are appropriate for the product being filled.

Appearance

Recycled resin may affect color, clarity, specking or visual consistency depending on material and grade.

Performance

Evaluate package strength, dimensional consistency, closure fit and distribution performance.

Regulatory Requirements

Confirm that the specific recycled material is suitable for the intended product and market.

Supply & Cost

PCR availability, quality, consistency and pricing can vary by resin grade and market conditions.

Common Misconceptions

What Should Packaging Buyers Avoid Assuming?

“Mechanical recycling turns plastic back into virgin resin.” Mechanically recycled resin is recovered and reprocessed plastic. Its properties and appearance may differ from virgin material.
“All PCR performs the same.” PCR quality can vary based on source material, sorting, contamination, processing and grade.
“Any plastic can simply be mechanically recycled together.” Different resins can have different processing requirements and may need to be separated into compatible material streams.
“If a package is recyclable, it will definitely become PCR.” Actual recycling depends on collection, sorting, processing and viable end markets for the recovered material.
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Sustainability Simplified™ in Under a Minute

What Is Mechanical Recycling?

Suggested Narration

“Mechanical recycling takes used plastic packaging and physically processes it into recycled material. The plastic is collected, sorted, cleaned, ground into flakes and reprocessed into feedstock that can be used in suitable new products or packaging. The quality of the recycled material depends heavily on the incoming material, contamination, sorting and processing.”

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Sustainability Simplified™ — At a Glance

Three Things to Remember About Mechanical Recycling

It Physically Reprocesses Plastic The material is sorted, cleaned, ground and reprocessed rather than intentionally broken into its original chemical building blocks.
Material Quality Matters Sorting, contamination and the incoming material stream can affect the quality of recycled resin.
Application Matters Recycled material should be evaluated against product compatibility, performance, regulatory, appearance, supply and cost requirements.

Frequently Asked Questions

Mechanical Recycling FAQs

What is mechanical recycling?
Mechanical recycling is a process that physically collects, sorts, cleans and reprocesses plastic into recycled feedstock without intentionally breaking the polymer into its basic chemical building blocks.
How does mechanical recycling work?
A typical process may involve collection, material sorting, cleaning, grinding or flaking, reprocessing and conversion into recycled resin or feedstock for suitable new applications.
What plastics are mechanically recycled?
PET and HDPE are common rigid-packaging resin streams associated with mechanical recycling, while polypropylene and other materials may also have recycling pathways depending on collection, sorting, processing capability and end markets.
What is the difference between mechanical recycling and chemical recycling?
Mechanical recycling physically reprocesses plastic while retaining the polymer as plastic. Chemical recycling uses chemical or thermal conversion processes to transform plastic into chemical feedstocks, intermediates or other outputs.
Does mechanical recycling create PCR?
It can. Mechanically processing plastic recovered after consumer use can produce post-consumer recycled material that may be used in suitable new products or packaging.
Can mechanically recycled resin be used in packaging?
Yes, depending on the resin grade, package, product, performance requirements, regulatory suitability and intended application.
Why can recycled plastic look different from virgin plastic?
Recycled material can contain variation from its source stream and processing history, which may influence color, clarity, specking and overall appearance.
Can plastic be mechanically recycled indefinitely?
Material properties can change through repeated use and processing, and recovered resin quality depends on many factors. Recycled material may therefore move into different applications over time rather than being repeatedly recycled into the same product indefinitely.
Does recyclable packaging automatically get mechanically recycled?
No. Actual recycling depends on collection, consumer participation, sorting, contamination, processing capacity and demand for the recovered material.

Applying Recycled Resin to Real Packaging

Considering PCR? Start With the Package Requirements.

Empire EMCO helps manufacturers evaluate rigid packaging options based on resin, recycled-content percentage, package performance, product compatibility, appearance, supplier capabilities, regulatory requirements, sourcing, availability, cost and sustainability goals.

Start a Sustainability Packaging Review Start a Packaging Project
Educational Information: Sustainability Simplified™ provides general packaging education and is not intended as legal, regulatory, recycling-certification or environmental-claims advice. Recycling availability, recycled-material quality and suitability vary by resin, package design, collection stream, processing technology, application, market and local infrastructure. Manufacturers should confirm current requirements and qualify recycled materials for the specific package and intended use.