A guide to recycling plastic


A guide to recycling plastic

Authored By: SDI Plastics

Recycling plastic is vital to environmental sustainability and responsible waste management. But how exactly does the recycling of plastic work?

In this guide, we’ll explore the ins and outs of plastic recycling, including the journey recycled materials take, the various recycling processes, the end products made from recycled plastic manufacturer, current innovations, and ways individuals and communities can boost recycling participation.

An introduction to plastic recycling

Plastic use has increased exponentially around the world due to this versatile, mouldable material being incorporated into endless products. 

However, our planet is now overflowing with plastic waste that takes an incredibly long time to decompose in landfills. Recognising the environmental impact, recycling plastic involves having used materials go back into service rather than discarding them. 

Understanding recycling helps individuals make a more concerted effort to correctly dispose of plastics. For plastic product manufacturers, knowing how recycling works enables them to incorporate more sustainable practices.

The basics of recycling and how does recycling plastic work?

Recycling prevents waste by collecting used, disposable materials, reprocessing them and creating new products.

Introducing the Circular Economy approach.

A Circular Economy seeks to eliminate waste and enable the continual use of resources. It is regenerative by design, using circular systems for production, consumption, and resource recovery. In contrast to the dominant linear economic model of taking resources, making products, and disposing of them after use, a Circular Economy aims for closed loops. Materials get cycled continuously through different phases.

When it comes to plastics, this means discarded products and packaging return into manufacturing supply chains instead of ending up as pollution or landfill. Recycling fits firmly within circular economic goals of extracting maximum value from resources while in use, then recovering and regenerating materials at end-of-life.

Overall, recycling is a vital component of a Circular Economy that reduces residual waste, conserves resources, averts pollution, saves energy and water, and decreases greenhouse emissions. Expanding recycling aligns with sustainability principles and responsible waste management.

Many materials are commonly recycled, including paper, glass, aluminium, and various plastic types. 

While not all plastics can be recycled, some of the most ubiquitous plastic products are made from recyclable plastic resins, including polythene terephthalate (PET or PETE), high-density polythene (HDPE), polyvinyl chloride (PVC), low-density polythene (LDPE), polypropylene (PP), and polystyrene (PS).

The Circular Economy approach

The circular economy represents a fundamental shift from the traditional linear model of “take-make-dispose” to a more sustainable and regenerative approach. It emphasises minimising waste and maximising the value of resources by promoting durability, reusability, and recycling throughout the entire product lifecycle. In the circular economy, products are designed to last longer, with an emphasis on repair, reuse, and remanufacturing rather than disposal. Materials and components are recovered and recycled at the end of their life, creating closed-loop systems where resources are continuously circulated within the economy. This reduces the need for virgin resource extraction, minimises waste generation, and promotes resource efficiency.

To achieve a circular economy, collaboration and innovation are essential. Stakeholders from diverse sectors, including businesses, governments, consumers, and innovators, must work together to develop and implement sustainable practices and solutions. This involves designing products for longevity and recyclability, adopting innovative business models such as product-as-a-service, and investing in infrastructure for recycling and recovery. By embracing the circular economy approach, societies can build more resilient and sustainable economies that minimise environmental impact, conserve resources, and foster innovation and economic growth for the benefit of present and future generations.

For plastic injection moulding companies, adopting a Circular Economy mindset is critical for driving sustainability. Some key strategies include:

  • Design for circularity: Conceive plastic parts and products focused on durability, reuse, and recyclability. Incorporate recycled materials, avoid toxic additives, and enable disassembly.
  • Industrial symbiosis: Exchange manufacturing by-products with other industries to cascade material utility. For instance, plastic residues can provide re-use for 3D printing, fuel, or construction.
  • Invest in advanced recycling: Adopt chemical processes to break plastics down into purified streams for remodelling. This increases quality recycled resin volumes.
  • Recover value: Install programs retrieving used products from consumers to capture value in end-of-life plastics. Enable takeback, then remanufacture and remarket them.
  • Partnerships: Collaboration across the value chain boosts innovation towards circular plastic material flows. Form strategic partnerships with recycling companies and sustainability-driven brands for continued progress.

The journey of recyclables

For plastic recycling to work, used materials need to successfully journey through a system starting from collection points, undergoing sorting, cleaning, and processing, before finally being manufactured into new plastic goods.

It begins when individuals or institutions place plastics marked with recycling codes like PET, HDPE, or PP into recycling bins. Municipal or private waste collectors transport these first to materials recovery facilities to be sorted and baled based on polymer type and colour. The separated plastics are then sent to specialist plastic reprocessing facilities domestically or overseas.

There is also an onsite plastic recycling process adopted by some manufacturers like SDI Plastics. Here, plastic waste generated during production is captured, cleaned, shredded, and directly fed back into the manufacturing process. This closed-loop recycling system right at the factory where plastic goods are moulded enables direct circularity and helps eliminate waste significantly. Production ‘rejects’ and products that do not meet customer requirements, are regrinded, put back into the production process and remodelled into new plastic parts. Such onsite initiatives allow for greater quality control, secure material streams, and instant circularity without relying solely on external recycling pathways. Large volumes of quality recycled materials can be consistently produced this way.

Here, further intricate sorting using technologies like near-infrared scanners occurs before plastics are shredded and washed. The clean flakes or pellets produced go on to be melted and remoulded into recycled plastic goods, thus completing the cycle.

The recycling processes for plastic

The recycling processes for plastic

There are several key processes involved in turning used plastic into usable materials for manufacturing new products:

1. Cleaning and shredding

Collected plastics contain various contaminants. It is important that the plastic materials are not mixed as part of the recycling process. All granulators are cleaned thoroughly before regrinding the plastic ‘waste’ material to avoid cross contamination. The plastic is then regrinded, for size reduction, producing plastic ‘granules’. The resulting plastic granules or pellets provide the raw materials that will be recycled back into a production cycle, which is run to produce a final product.

2. Identifying and separating polymers

Not all plastics can be recycled together, and they must be accurately identified and separated first, based on the type of material. Machine operators will re-grind and allocate grinders specific to production runs, this alleviates any issues during the recycling process, with regards to mixing materials and minimises errors during the re-grind process. 

Chemical markers in plastic polymers also enable detection under certain light wavelengths. With precise identification and sorting, plastics can then undergo suitable recycling processes.

Mechanical and chemical recycling

There are two main recycling methods: mechanical and chemical.

Mechanical recycling involves melting, extruding, and remoulding scrap plastic chips or granules. After sorting and shredding, the plastic granules are directly reformed into plastic products like outdoor furniture, flooring, insulation, pipes and containers.

Chemical recycling first breaks the polymer chains down into their molecular building blocks using chemical processes like pyrolysis, gasification, or depolymerisation. These output chemical ingredients then become feedstock to manufacture new plastics or even other chemicals. The derived oils or gases can also be processed into fuel.

The challenges

While the technology exists for successful plastic recycling, contamination, quality control, and securing stable markets for recycling, there still remain some obstacles. When mixed plastics or non-recyclables enter recycling streams, this lowers the quality and properties of the output material.

Repeated recycling of plastic faces technical limitations due to the gradual degradation of polymers with each melt-remould cycle. This degradation alters the physical and chemical properties of the plastic, reducing its quality and performance over time. As a result, the number of times plastic can be effectively recycled is limited, making it challenging to maintain high-quality recycled plastic materials for prolonged use in manufacturing processes. These technical constraints highlight the importance of not only improving recycling technologies but also reducing plastic consumption and promoting alternative materials to mitigate the environmental impact of plastic waste.

Research targeting innovative chemical markers, stronger adhesive properties, and detecting contaminants aims to improve plastic recycling systems. Advanced sorting robots, enzyme baths, and modifications enable the production of high-grade recycled resin. 

Nevertheless, recycling cannot resolve all waste issues. Avoiding unnecessary plastic usage through reduced production and consumption is equally crucial.

End products and market demand

Recycled plastic passes back into the manufacturing stream to be remade into diverse goods. Packaging accounts for the largest share at 25%, as recycled PET and HDPE have products turned into clamshell containers, bottles, strapping bands, and bags. Piping, plates, furniture, clothing, car parts, construction materials, office supplies, and electronics also contain sizable proportions of recycled plastic content.

These recycled plastic products appeal to environmentally-conscious consumers and companies aiming for sustainability credentials and zero-waste targets. Major brands like Unilever, Lego, HP, Adidas, and Patagonia now incorporate recycled plastics into their packaging and products. Governments also increasingly legislate the minimum recycled content of plastic goods.

Building local remanufacturing capabilities retains value along the supply chain and stimulates domestic recycling markets. With circular economic principles permeating business decisions, recycled plastics present a profitable commodity, fueling growth opportunities.

Overcoming recycling challenges

While plastic recycling already diverts billions of bottles, containers, and bags from landfills, less than 10% of plastic is recycled currently in Australia, with room for major expansion.

Contamination from mixed plastics and non-recyclables complicates sorting and reprocessing. But innovations like digital watermark recognition technology and enzymatic processes to remove labels promise to overcome this.

Quality inconsistencies between batches of recycled plastics can deter manufacturers requiring durability, strength, and aesthetic qualities. Advances in polymer science and new chemical modification techniques now enable high-grade resin quality as good as virgin plastics.

Insufficient market demand also hinders recycling participation. Governments are, however, harnessing procurement policies and incentive schemes to increase recycled material uptake across sectors.

Policies and legislation

Beyond technological solutions, governmental policies and legislation play a powerful role in transforming recycling ecosystems.

Product stewardship programmes like container deposit schemes boost return rates while motivating companies to minimise waste. Mandatory recycled content targets, coupled with bans on single-use and hard-to-recycle plastics, will further expand markets. Landfill levies and incentives for plastic manufacturing additionally encourage sustainable design and recycling.

Standardisation around plastic labelling, classifications, and safe contaminant thresholds also aids sorters and reprocessors. Furthermore, many governments now regard plastic waste as a valuable resource rather than an item requiring disposal.

Everyday contributions to plastic recycling

While governments and consumers play a role, manufacturers and industry have a greater responsibility for overcoming recycling issues through their business practices. Some critical initiatives include:

  • Product stewardship programs take on financial and physical responsibility for recovering and recycling plastics.
  • Voluntary or legislated targets to drastically increase recycled material input into production over virgin plastic.
  • Eliminating hazardous and hard-to-recycle plastic components through innovative design adjustments.
  • Investing in advanced sorting and chemical recycling technologies to boost quality outputs.
  • Pursuing alternative business models focused on circularity—product-as-a-service, take-back schemes
  • Participating in collaborative industry networks to progress solutions like tracer technologies, collection incentives, safe contaminant thresholds
  • Using procurement power and supply chain influence to reward sustainable practices.

This proactive leadership from recycled plastic manufacturer is indispensable for transitioning to a circular economy model. Their processes and product decisions significantly impact recycling outcomes on a mass scale.


Grasping the processes and barriers behind recycling empowers both individuals and business leaders to enact positive change. Transforming today’s pressing plastic waste issues relies on a concerted effort across governments, manufacturers, and consumers.

While simple everyday consumer actions make a cumulative difference, the onus falls heaviest on plastic product designers, manufacturers, and distributors. Implementing responsible waste management systems and embracing circular economic principles promise to accelerate large-scale recycling participation.

Specific business initiatives needed include:

  • Designing products and production processes focused on recyclability
  • Investing in advanced recycling and sorting technologies
  • Setting ambitious recycled content targets
  • Building robust collection programs and alternative business models
  • Participating in collaborative multi-stakeholder networks
  • Leveraging procurement and supply chain influence

Our environmental future depends on transitioning to closed-loop systems that eliminate plastic waste. The sustainability of our environment relies on the adoption of closed-loop systems aimed at eradicating plastic waste. This necessitates a comprehensive embrace of circular principles. Recycling stands as a crucial component within this intricate transformational framework, spanning both production and consumption systems. Recycled plastic manufacturer hold a pivotal position within our communities and must take the lead in reenvisioning plastic production processes, emphasising the circular economy approach and recycling to instigate a shift in consumer mindset.

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