Plastic Recycling
Plastic Recycling
Circular economy is not just one form
In the global issue of plastic reduction and sustainable development, "recycling" has become a high-frequency term.
In the global issue of plastic reduction and sustainable development, "recycling" has become a high-frequency term. However, there is not only one form of circular economy. From PET bottles to textile fibers, from high-purity recycling from bottle to bottle to degraded utilization from bottle to clothing, the fate of plastics extends in both closed-loop and open-loop recycling systems. Understanding the differences between these two is the key to understanding the plastic recycling system.
1. Closed loop recycling: high standard multiple controllable cycles
Closed-loop Recycling:
The so-called closed-loop recycling refers to the reprocessing of recycled materials into products of the same type. Taking PET beverage bottles as an example, discarded bottles can be transformed into new PET bottles through cleaning, crushing, melting, and recycling. In this process, PET material forms a cycle between "product raw material
The biggest feature of closed-loop recycling is the maximum preservation of material value and performance. Its advantages include:
Short cycle path and high value: Recycled materials can be returned to the food grade application field, with high market recognition and economic returns.
High purity requirements: strict sorting and decontamination must be carried out to ensure no impurities or abnormal materials.
Can be reused multiple times, significantly reducing carbon footprint: each high-quality recycling reduces reliance on primary petrochemical resources.
However：
a closed loop is not a 'perpetual loop'. Although PET is a recyclable thermoplastic polymer, problems such as chain scission, thermal oxidation, and loss of additives occur during each reprocessing process：
Chain breakage leads to a decrease in molecular weight, resulting in a decrease in the mechanical strength, transparency, and other properties of recycled PET;
Impurities residue (such as bottle cap PP, labels) can trigger oxidation reactions at high temperatures, causing the material to turn yellow or cloudy;
The loss of antioxidants, anti UV agents and other additives gradually deteriorates the performance of recycled materials.
Therefore：
PET can usually only be recycled in a closed loop for about 3-5 times. After severe physical property degradation, it will be "downgraded and utilized" in products such as fibers, strapping, and building materials boards, entering the open-loop recycling stage. From a lifecycle perspective, closed-loop systems in reality are closer to a composite system of "finite closed-loop+degraded cycle".
2. Open loop recycling: a "changing track" cycle that extends the lifespan of materials
Plastic recycling:
Unlike closed-loop recycling, open loop recycling refers to the conversion of recycled materials into different types of products. For example, PET beverage bottles are no longer made into new bottles after recycling, but instead become textile fibers, carpets, packaging tapes, and so on.
The characteristic of an open-loop system is "changing lanes to extend lifespan":
Although the material no longer maintains its original application, it can still continue to circulate in the economic system.
The recycling process is relatively loose, with low purity requirements and a small technical threshold.
Lower cost, more suitable for widespread promotion.
However：
open-loop recycling cannot truly achieve the "closed regeneration" of resources. These downgraded materials will eventually enter the scrap stage and are difficult to recycle again. Most open-loop products cannot be regenerated into raw material grade plastics due to mixed materials or composite structures, and are often disposed of by incineration or landfill.
Therefore, the industry often views it as a "delayed abandonment" rather than a true cycle.
3. Differences and Realistic Challenges
Domestic situation: Open loop is the main focus, and insufficient participation from the consumer end brings systemic difficulties.
:In China, the mainstream path for recycling waste PET bottles is still open-loop utilization such as "bottle to fiber", and the proportion of food grade closed-loop recycling from bottle to bottle is relatively limited; A large amount of recycled materials enter non food contact fields such as textiles. Consumers are generally "disposable" and lack legal obligations to participate in deposit/recycling systems or mandatory classification, which limits the purity and recycling efficiency at the source and poses significant difficulties for high-quality closed-loop systems. This judgment is consistent with academic research: studies on PET recycling in China have shown that it is mainly for open-loop recycling and mainly used for regenerating fibers; At the same time, China is also piloting deposit refund (DRS) and a more comprehensive collection network, but overall it is still in the promotion stage.
Why is a closed loop more suitable for food contact?
If the goal is to return to food grade applications (such as "bottle to bottle"), open-loop paths face higher safety and compliance pressures - once the recycling logistics are contaminated, using them as food contact materials will significantly increase audit and remediation costs; The system of "building a closed loop from the beginning" (high-purity collection, rapid turnover, and full process traceability) not only reduces secondary pollution, but also has higher resource efficiency, lower recycling costs, and better reflects the responsibility of users.
China has a comprehensive and constantly updated standard system for food contact materials (FCM), and has put forward stricter safety and compliance requirements for recycled plastics entering the food contact field. In recent years, departments such as NHC and SAMR have issued or revised food contact materials and related standards multiple times, and the market and regulatory "high threshold" objectively require cleaner and more traceable closed-loop solutions.
4. Closed loop vs open-loop: Collaborative construction of a realistic recycling system
In practice, a complete plastic cycle system is often not a single mode, but the coexistence of closed-loop and open-loop. The former maintains high-quality recycling and raw material value, while the latter absorbs retired materials to extend their service life. A typical PET lifecycle may be as follows:
Native PET → Bottle → Recycling → Recycled rPET → New Bottle → Recycled rPET → Fiber/Film → Waste
5.Why still pursue a closed loop?
Although closed-loop is not perfect, it is still the direction of industry efforts for three main reasons:
Reduce dependence on native petrochemical resources: With each additional closed-loop, there is less consumption of new materials, resulting in a decrease in carbon emissions and energy consumption.
Promoting quality management and standardization: Only when the sorting, cleaning, and testing systems are perfected, can recycled materials re-enter the food grade application field.
Guiding the design of recyclable and reusable products? The simplification of bottle body, color reduction, and detachable design all stem from the need to achieve a closed-loop system.
