Sinopec’s biodegradable PBST film passes key Xinjiang cotton trial, advancing China’s green agriculture goals

China Petroleum & Chemical Corporation (HKG: 0386), known globally as Sinopec, has achieved a major milestone in its sustainability efforts, successfully concluding a pilot program of its PBST (polybutylene succinate-co-terephthalate) biodegradable mulch film in cotton fields across the Xinjiang Uygur Autonomous Region. The results show that PBST film delivers comparable cotton yields to conventional polyethylene mulch film, while also fully degrading into environmentally benign substances. This development marks a turning point in the effort to tackle residual plastic pollution across China’s agricultural heartlands.

The pilot was conducted in Wusu, one of Xinjiang’s key cotton-producing cities. As cotton remains a vital component of China’s agricultural output, with Xinjiang accounting for more than 80 percent of national cotton production, the successful trial of biodegradable alternatives could set the tone for large-scale adoption of green farming inputs across the region. Sinopec’s PBST product, developed through proprietary in-house innovation, met all performance benchmarks related to yield, soil moisture retention, thermal insulation, and degradation kinetics.

What problem does PBST film solve in China’s cotton fields?

For decades, Xinjiang’s cotton farmers have relied on polyethylene mulch film to retain soil moisture and regulate temperature, boosting yields in an otherwise harsh environment. However, polyethylene film is non-biodegradable and difficult to recover fully after the harvest season. Over time, fragments accumulate in the soil, creating a serious environmental challenge. Known as “white pollution,” this residue reduces soil fertility, disrupts microbial activity, and increases labor costs associated with post-harvest cleanup.

Previous efforts to replace polyethylene with biodegradable options such as PBAT (polybutylene adipate-co-terephthalate) have fallen short due to premature degradation. PBAT tends to break down too early in the cotton growing cycle, especially before the boll-forming stage, resulting in moisture loss and stunted crop development. Sinopec’s PBST film, by contrast, demonstrated superior resistance to UV radiation and maintained its structural integrity throughout the critical growth phases.

Field observations confirmed that the PBST mulch retained heat and moisture on par with polyethylene mulch films. After fulfilling its agronomic function, the PBST material began to degrade naturally into water, carbon dioxide, and mineral matter within one to three years, eliminating the need for manual retrieval and disposal.

How does PBST differ from other biodegradable films like PBAT?

One of the biggest drawbacks of PBAT is its limited weather resistance. In Xinjiang, where intense sunlight and large diurnal temperature swings are common, PBAT film often begins breaking down before the crop cycle is complete. This undermines its benefits as a moisture and thermal barrier and reduces overall crop output.

Sinopec’s PBST film overcomes these limitations with enhanced anti-UV capabilities and superior moisture retention. It does not disintegrate prematurely during the growing season and instead begins to break down only after the plant’s lifecycle is complete. The polymer’s design allows it to fully degrade within a controllable time window, offering predictability and environmental safety.

Long-term trials have shown that PBST films can be tailored to match different climatic conditions and crop types. The material’s performance is consistent across varied regions, reinforcing its credibility as a scalable agricultural input.

What steps has Sinopec taken to commercialize PBST at scale?

Sinopec moved decisively to commercialize PBST earlier this year by commissioning a dedicated production facility with an annual output of 60,000 tons at its Hainan Refining & Chemical complex. This industrial-scale capacity makes it the first plant of its kind globally and positions Sinopec as a leader in biodegradable plastics tailored for agricultural use.

In April 2025, just weeks after the plant’s commissioning, Sinopec partnered with agricultural authorities in Xinjiang and the Liaoning Dongsheng Group to initiate a large-scale PBST mulch film pilot. Over 10,000 mu of cotton fields, equivalent to approximately 1,650 acres, were cultivated using PBST film in Wusu City and Kuitun City, two of Xinjiang’s most important cotton-producing centers.

By October, third-party yield assessments confirmed that fields covered with PBST mulch achieved cotton output equivalent to traditional polyethylene-covered plots. Moreover, the PBST mulch decomposed at a visibly faster rate once the cotton harvesting phase concluded. The film showed no adverse impact on crop health, soil condition, or farm operations, suggesting that the transition from PE to PBST could be smooth and cost-effective.

Why is Xinjiang critical to China’s biodegradable materials transition?

Xinjiang plays a pivotal role in China’s cotton supply chain. However, the region also faces one of the most severe cases of residual film pollution due to its heavy reliance on plastic mulch. The lack of efficient post-harvest collection processes and the sheer volume of plastic used each season have turned Xinjiang’s soil into a repository of non-degradable waste. As China pushes for agricultural modernization and ecological sustainability under its national green development goals, Xinjiang is increasingly seen as the testing ground for new technologies like biodegradable mulch film.

Sinopec’s successful pilot brings a commercially viable solution to this long-standing problem. By integrating PBST into cotton cultivation without sacrificing yield or increasing operational complexity, the firm has created a roadmap for the region to shift away from pollutive materials. It also helps local governments and farmers meet emerging regulatory mandates that call for reductions in non-degradable agri-plastics.

How are industry watchers interpreting Sinopec’s PBST milestone?

Industry analysts believe this pilot strengthens Sinopec’s reputation as a frontrunner in China’s green materials innovation drive. By leveraging its vertically integrated value chain, from petrochemical feedstocks to advanced polymer R&D and agricultural deployment, the company can develop, test, and scale novel materials more efficiently than many of its peers.

Observers also point to the timing of this success. With China’s 14th Five-Year Plan emphasizing circular economy models and agricultural decarbonization, the demand for biodegradable agri-inputs is expected to rise sharply. Sinopec’s early investments in PBST give it a competitive edge not only within China but also in other major cotton-producing regions across Asia, Africa, and Latin America where residual film pollution is a growing concern.

There is also speculation that Sinopec may explore licensing deals or international partnerships to expand PBST’s reach. The product’s alignment with global ESG criteria adds to its appeal among institutional investors and regulators alike.

What’s next for PBST and Sinopec’s green materials pipeline?

Following the success of the Xinjiang pilot, Sinopec is expected to initiate additional PBST trials in other crop segments such as maize, peanuts, and vegetables. These crops also depend heavily on mulch film for optimal growth and are often cultivated in regions vulnerable to microplastic contamination.

The company’s R&D pipeline reportedly includes enhancements to the PBST formulation to fine-tune degradation timing and expand climatic adaptability. Meanwhile, sales and distribution teams are exploring partnerships with local cooperatives and agricultural service providers to embed PBST into mainstream planting practices.

At the policy level, Sinopec’s PBST success is likely to inform national standards for biodegradable agricultural plastics. Government regulators are expected to increase pressure on polyethylene use in farming, which could accelerate commercial adoption of alternatives like PBST.

With international momentum building around sustainable farming inputs, PBST could become one of the key materials supporting the next wave of agricultural innovation. For China, it offers a way to reduce environmental damage, protect arable land, and position itself as a global leader in green materials.

Key takeaways: Sinopec’s PBST biodegradable mulch film proves commercially viable in Xinjiang cotton fields

• Sinopec completed a large-scale PBST mulch film pilot in Wusu and Kuitun cotton fields, confirming yields equivalent to polyethylene mulch.
• The PBST film demonstrated strong UV resistance, moisture retention, and stability throughout the cotton growth cycle, unlike earlier biodegradable materials such as PBAT.
• Third‑party assessments verified that PBST degrades fully within one to three years into water, carbon dioxide, and mineral matter, eliminating the need for post‑harvest film retrieval.
• The success of the pilot addresses Xinjiang’s long-standing residual plastic pollution problem caused by polyethylene mulch accumulation.
• Sinopec has commissioned a 60,000‑ton‑per‑year PBST industrial production facility in Hainan to support national-scale adoption.
• The material aligns with China’s agricultural sustainability mandates and is expected to see wider use across crops and regions as policy support increases.
• Industry analysts believe PBST strengthens Sinopec’s position in green chemical innovation and may attract interest from global cotton‑producing regions.
• Additional trials in other crop categories and climate zones are expected to determine PBST’s wider commercial deployment across China’s agriculture sector.