Use zinc isoctanoate to improve the anti-aging properties of plastic products

Overview and application background of zinc isoctanoate

Zinc 2-Ethylhexanoate, with the chemical formula Zn(C8H15O2)2, is an organic zinc compound, which is widely used in plastics, coatings, rubber and other fields. In its molecular structure, zinc ions bind to two isocitate roots, giving the compound excellent thermal stability and antioxidant properties. In the plastics industry, zinc isoctanoate is mainly used as an anti-aging agent and a heat stabilizer, which can effectively delay the aging process of plastic products and extend its service life.

With the increasing global plastic production, the aging problem of plastic products has attracted increasing attention. Plastic aging refers to the changes in the physical properties and chemical structure of plastic materials during long-term use due to environmental factors (such as ultraviolet rays, oxygen, temperature changes, etc.), which in turn affects the appearance and function of the product. Common aging phenomena include discoloration, brittleness, cracking, and decreased strength. These problems not only affect the aesthetics and performance of plastic products, but may also bring safety hazards. Therefore, how to improve the anti-aging performance of plastic products has become one of the key issues that need to be solved in the plastic industry.

In recent years, researchers have found that zinc isoctanoate, as a highly effective anti-aging agent, can significantly improve the weather resistance of plastic products in many aspects. First of all, zinc isoctanoate has good thermal stability and can effectively inhibit the free radical reaction in plastics under high temperature conditions and prevent material degradation. Secondly, it can absorb ultraviolet rays and reduce the destruction of ultraviolet rays on the plastic molecular chains. In addition, zinc isoctanoate also has a certain lubricating effect, which can improve the processing performance of plastics and reduce production costs. Therefore, zinc isoctanoate has broad application prospects in the field of anti-aging of plastics and has attracted more and more attention.

This article will conduct in-depth discussion on the application mechanism, product parameters, and practical application effects of zinc isoctanoate in plastic anti-aging, and analyze its performance in different plastic systems in combination with new research progress at home and abroad. At the same time, the article will also cite a large number of foreign documents and famous domestic documents to provide readers with a comprehensive and authoritative reference basis.

The chemical structure and properties of zinc isoctanoate

The chemical structure of zinc isoctanoate is the basis of its unique properties. Its molecular formula is Zn(C8H15O2)2, where zinc ions (Zn²⁺) and two isocitate groups (C8H15O₂⁻) are bound through coordination bonds. The long-chain alkyl structure of isoocitate imparts good solubility and dispersion of the compound, allowing it to be evenly distributed in the plastic matrix, thereby exerting an excellent anti-aging effect. Specifically, the chemical structure of zinc isoctanoate is as follows:

Zn ion (Zn²⁺): As a metal center, zinc ion has strong coordination ability and can form stable complexes with a variety of functional groups. During the plastic aging process, zinc ions can capture free radicals and terminate the chain reaction, thereby suppressingDegradation of materials.
Isooctanoate (C8H15O₂⁻): Isooctanoate is a long-chain fatty acid salt whose molecule contains a carboxyl group (-COO⁻) and a longer alkyl chain ( -C8H15). The carboxyl group can form a stable coordination bond with the zinc ions, while the alkyl chain imparts good hydrophobicity and lubricity to the compound. This structure allows zinc isoctanoate to have excellent compatibility and dispersion in plastic substrates and can remain stable over a wide temperature range.

Physical and chemical properties

The physicochemical properties of zinc isooctanoate determine its application effect in plastics. The following are its main physical and chemical parameters:

parameters	value	Unit
Molecular Weight	376.74	g/mol
Density	1.09	g/cm³
Melting point	95-97	°C
Boiling point	270	°C
Solution	Easy soluble in organic solvents, slightly soluble in water	–
Refractive index	1.46	–
Color	White to light yellow	–
odor	Slight Ester Odor	–

As can be seen from the table, zinc isoctanoate has a lower melting point and a higher boiling point, which is suitable for use during plastic processing. Its density is moderate and easy to mix with other additives. In addition, zinc isoctanoate is easily soluble in organic solvents but slightly soluble in water, which makes it have good dispersion in the plastic matrix and can be evenly distributed throughout the material, thereby exerting an excellent anti-aging effect.

Thermal Stability

Thermal stability is one of the important characteristics of zinc isoctanoate as an anti-aging agent. Research shows that zinc isoctanoate can effectively inhibit the free radical reflux in plastics under high temperature conditionsIt should prevent material degradation. According to literature, the thermal decomposition temperature of zinc isoctanoate is about 270°C, which is much higher than the processing temperature of most plastics (usually between 150-250°C). This means that during the plastic processing process, zinc isoctanoate will not decompose, and can maintain its activity and continue to play a role.

To further verify the thermal stability of zinc isoctanoate, the researchers conducted thermogravimetric analysis (TGA) experiments. The results show that at below 200°C, the mass of zinc isoctanoate is almost no loss; even at 300°C, the mass loss is only about 5%. This shows that zinc isoctanoate has excellent thermal stability and can maintain its anti-aging properties for a long time under high temperature environments.

Optical Performance

In addition to thermal stability, zinc isoctanoate also has good optical properties. Studies have shown that zinc isoctanoate can absorb ultraviolet rays and reduce the destruction of ultraviolet rays on plastic molecular chains. Ultraviolet rays are one of the main causes of plastic aging, especially in plastic products used outdoors, which can accelerate the degradation of materials. Zinc isocaprylate protects the plastic matrix from UV damage by absorbing UV light and converting it into thermal or chemical energy.

To evaluate the UV absorption properties of zinc isoctanoate, the researchers tested it using an ultraviolet-visible spectrometer (UV-Vis). The results show that zinc isoctanoate has obvious absorption peaks in the wavelength range of 200-400nm, especially in the 300-350nm band. This band is the main component of ultraviolet rays, so zinc isoctanoate can effectively block ultraviolet rays and protect plastic materials from their influence.

Luction Performance

The long-chain alkyl structure of zinc isooctanoate imparts certain lubricating properties. During plastic processing, lubricants can reduce the viscosity of the melt, improve fluidity, thereby improving production efficiency and reducing equipment wear. Studies have shown that zinc isoctanoate, as an internal lubricant, can reduce the friction between molecules in the melting state of plastic, making the melt more likely to flow. In addition, zinc isoctanoate also has a certain external lubrication effect, which can form a thin lubricating film on the surface of the mold to prevent plastic from adhering to the mold, thereby improving the mold release effect.

To verify the lubricating properties of zinc isoctanoate, the researchers conducted a melt index (MFI) test. The results show that after the addition of zinc isoctanoate, the melting index of the plastic is significantly improved and the fluidity is significantly enhanced. This shows that zinc isoctanoate can not only improve the processing performance of plastics, but also reduce production costs and improve production efficiency.

Mechanism of action of zinc isoctanoate in plastic anti-aging

As an efficient anti-aging agent, zinc isooctanoate’s mechanism of action in plastics is mainly reflected in the following aspects: free radical capture, ultraviolet absorption, metal ion passivation and synergistic effects. These mechanisms work together to significantly delay the aging process of plastics and extend their service life.

Free Radical Capture

One of the important reasons for plastic aging is the free radical reaction. Under the influence of external factors such as high temperature, light, and oxygen, some functional groups in the plastic molecular chain will undergo an oxidation reaction to form free radicals. These free radicals can trigger a chain reaction, causing the plastic molecular chain to break, which in turn causes the material to degrade. The zinc ions in zinc isoctanoate have strong coordination ability, can react with free radicals, terminate the chain reaction, and thus inhibit the degradation of the material.

Study shows that zinc isooctanate can effectively capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from further triggering chain reactions. According to literature reports, the free radical capture efficiency of zinc isoctanoate is as high as more than 90%, far superior to traditional anti-aging agents. In addition, zinc isoctanoate can react with hydroxyl radicals (•OH) to produce stable zinc compounds, further reducing the number of radicals.

To verify the free radical capture capability of zinc isoctanoate, the researchers conducted electron paramagnetic resonance (EPR) experiments. The results show that after the addition of zinc isooctanoate, the free radical signal in the plastic is significantly weakened, indicating that zinc isooctanoate can effectively capture free radicals and inhibit the occurrence of chain reactions.

Ultraviolet absorption

UV rays are one of the main causes of plastic aging, especially in plastic products used outdoors, which can accelerate the degradation of materials. Zinc isoctanoate can absorb ultraviolet rays and reduce the damage effect of ultraviolet rays on plastic molecular chains. Studies have shown that zinc isoctanoate has obvious absorption peaks in the wavelength range of 200-400nm, especially in the 300-350nm band. This band is the main component of ultraviolet rays, so zinc isoctanoate can effectively block ultraviolet rays and protect plastic materials from their influence.

To evaluate the UV absorption properties of zinc isoctanoate, the researchers tested it using an ultraviolet-visible spectrometer (UV-Vis). The results show that the absorption coefficient of zinc isoctanoate in the 300-350nm band is 0.1-0.2 cm⁻¹, indicating that it has strong UV absorption capacity. In addition, zinc isoctanoate can convert the absorbed ultraviolet energy into thermal or chemical energy, thereby avoiding the direct damage of ultraviolet rays to the plastic molecular chain.

Metal ion passivation

In some plastic systems, the presence of metal ions (such as copper, iron, manganese, etc.) can accelerate the aging process of the material. These metal ions can catalyze oxidation reactions, creating more free radicals, thereby aggravating the degradation of plastics. The zinc ions in zinc isoctanoate can react with these metal ions to form stable complexes that prevent them from catalyzing oxidation reactions. This effect is called “metal ion passivation”.

Study shows that zinc isoctanoate can effectively passivate common metal ions such as copper ions (Cu²⁺), iron ions (Fe³⁺) and manganese ions (Mn²⁺). According to literature reports, the complex constant of zinc isoctanoate and copper ions is 10⁵, and the complex with iron ions isocaprylic ionsThe combined constant is 10⁴, indicating that it has strong metal ion passivation ability. In addition, zinc isoctanoate can react similarly with other metal ions, further improving the anti-aging properties of plastics.

Synergy Effect

Zinc isooctanate has a good synergistic effect with other anti-aging agents (such as phenolic antioxidants, thiodipropionate, etc.). Studies have shown that when used in combination with phenolic antioxidants (such as BHT, Irganox 1010, etc.), the anti-aging properties of plastics can be significantly improved. This is because zinc isoctanoate and phenolic antioxidants work through different mechanisms, respectively: zinc isoctanoate mainly delays the aging of materials by capturing free radicals and absorbing ultraviolet rays, while phenolic antioxidants reduce hydroperoxides by reducing hydroperoxides to inhibit oxidation reaction. When used in combination, the two can complement each other and exert a stronger anti-aging effect.

To verify the synergistic effect of zinc isoctanoate and other anti-aging agents, the researchers conducted accelerated aging experiments. The results show that after the addition of zinc isoctanoate and phenolic antioxidants, the anti-aging performance of the plastic is significantly improved, and the aging time is extended by more than 50%. In addition, zinc isoctanoate can also have a synergistic effect with other types of anti-aging agents such as thiodipropionate, further improving the weather resistance of plastics.

The application effect of zinc isoctanoate in different plastic systems

Zinc isooctanoate is widely used in various plastic systems as a multifunctional anti-aging agent, including polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and polycarbonate (PC) wait. Different types of plastics have different chemical structures and physical properties, so the application effect of zinc isoctanoate in different plastic systems also varies. The following will introduce the application effects of zinc isoctanoate in several common plastics in detail.

Polyethylene (PE)

Polyethylene is a plastic material widely used in packaging, construction, agriculture and other fields, with excellent mechanical properties and chemical stability. However, polyethylene is easily affected by factors such as ultraviolet rays and oxygen during long-term use, resulting in material aging. Studies have shown that zinc isoctanoate can significantly improve the anti-aging properties of polyethylene and extend its service life.

According to literature reports, the anti-aging properties of polyethylene were significantly improved after adding 0.5% zinc isoctanoate. In the accelerated aging experiment, polyethylene samples without isoctanoate were significantly discolored and brittled after 7 days of exposure to ultraviolet rays and oxygen; while samples with isoctanoate were exposed under the same conditions14 The queen still maintains good appearance and mechanical properties. In addition, zinc isoctanoate can also improve the thermal stability of polyethylene and prevent the material from degrading at high temperatures.

To further verify the application effect of zinc isoctanoate in polyethylene, the researchers conducted tensile strength tests. The results show that after the addition of zinc isoctanoate, the tensile strength of polyethylene increased by 15% and the elongation of break was increased by 20%. This shows that zinc isoctanoate can not onlyDelaying the aging process of polyethylene can also improve its mechanical properties and improve product performance.

Polypropylene (PP)

Polypropylene is an important general-purpose plastic and is widely used in automobiles, home appliances, medical and other fields. Similar to polyethylene, polypropylene is also susceptible to factors such as ultraviolet rays and oxygen during long-term use, resulting in material aging. Studies have shown that zinc isoctanoate can significantly improve the anti-aging properties of polypropylene and extend its service life.

According to literature reports, the anti-aging properties of polypropylene were significantly improved after adding 1.0% zinc isoctanoate. In the accelerated aging experiment, polypropylene samples without isocaprylate showed obvious discoloration and embrittlement after 5 days of exposure to ultraviolet rays and oxygen; while samples with isocaprylate were exposed under the same conditions 10 The queen still maintains good appearance and mechanical properties. In addition, zinc isoctanoate can also improve the thermal stability of polypropylene and prevent the material from degrading at high temperatures.

To further verify the application effect of zinc isoctanoate in polypropylene, the researchers conducted impact strength tests. The results show that after the addition of zinc isoctanoate, the impact strength of polypropylene is increased by 25% and the toughness is increased by 30%. This shows that zinc isoctanoate can not only delay the aging process of polypropylene, but also improve its mechanical properties and improve the product’s performance.

Polyvinyl chloride (PVC)

Polidvinyl chloride is a commonly used engineering plastic and is widely used in building materials, wires and cables. However, polyvinyl chloride is susceptible to factors such as ultraviolet rays and oxygen during long-term use, resulting in material aging. Studies have shown that zinc isoctanoate can significantly improve the anti-aging properties of polyvinyl chloride and extend its service life.

According to literature reports, the anti-aging properties of polyvinyl chloride were significantly improved after adding 0.8% zinc isoctanoate. In the accelerated aging experiment, the polyvinyl chloride sample without isooctanoate showed obvious discoloration and embrittlement after 3 days of exposure to ultraviolet rays and oxygen; while the sample with isooctanoate was exposed under the same conditions. After 7 days, it still maintains good appearance and mechanical properties. In addition, zinc isoctanoate can also improve the thermal stability of polyvinyl chloride and prevent the material from degrading at high temperatures.

To further verify the application effect of zinc isoctanoate in polyvinyl chloride, the researchers conducted a bending strength test. The results show that after the addition of zinc isocitate, the bending strength of polyvinyl chloride was increased by 20% and the elastic modulus increased by 15%. This shows that zinc isoctanoate can not only delay the aging process of polyvinyl chloride, but also improve its mechanical properties and improve the product’s performance.

Polycarbonate (PC)

Polycarbonate is a high-performance engineering plastic that is widely used in electronics, optical, medical devices and other fields. However, polycarbonate is susceptible to factors such as ultraviolet rays and oxygen during long-term use, resulting in material aging. Research shows that zinc isoctanoate canIt can significantly improve the anti-aging properties of polycarbonate and extend its service life.

According to literature reports, the anti-aging properties of polycarbonate were significantly improved after adding 0.3% zinc isoctanoate. In the accelerated aging experiment, polycarbonate samples without isoctanoate showed obvious discoloration and embrittlement after 2 days of exposure to ultraviolet rays and oxygen; while samples with isoctanoate were exposed under the same conditions. After 5 days, it still maintains good appearance and mechanical properties. In addition, zinc isoctanoate can also improve the thermal stability of polycarbonate and prevent the material from degrading at high temperatures.

To further verify the application effect of zinc isoctanoate in polycarbonate, the researchers conducted a light transmittance test. The results show that after the addition of zinc isoctanoate, the light transmittance of polycarbonate increased by 10% and the haze decreased by 8%. This shows that zinc isoctanoate can not only delay the aging process of polycarbonate, but also improve its optical performance and improve the product’s performance.

Related research progress at home and abroad

The application of zinc isoctanoate in the field of anti-aging of plastics has attracted widespread attention, and domestic and foreign scholars have conducted a lot of research on this. The following will review the research results of zinc isoctanoate in plastic anti-aging in recent years, and focus on its application effects, mechanisms of action and future development trends in different plastic systems.

Progress in foreign research

Research Progress in the United States

In the United States, researchers have conducted in-depth research on the application of zinc isooctanoate in polyethylene (PE). According to a paper in Journal of Applied Polymer Science, zinc isoctanoate can significantly improve the UV resistance of polyethylene. Studies have shown that after adding 0.5% zinc isocitate, the UV absorption capacity of polyethylene increased by 30%, and the mechanical properties of the material hardly decreased after one year of exposure in an outdoor environment. In addition, the researchers also found that when combined with zinc isoctanoate and phenolic antioxidants (such as Irganox 1010), they can produce significant synergistic effects, further improving the anti-aging properties of polyethylene.

Another study published in Polymer Degradation and Stability shows that zinc isoctanoate can effectively inhibit free radical reactions in polyethylene and prevent material degradation. Through electron paramagnetic resonance (EPR) experiments, researchers found that zinc isooctanoate was able to capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from triggering chain reactions. This discovery provides theoretical support for the application of zinc isoctanoate in polyethylene.
Research Progress in Europe

In Europe, researchers are on zinc isoctanoate in polypropylene (PP)The application in the company has been extensively studied. According to a paper in the European Polymer Journal, zinc isoctanoate can significantly improve the thermal stability and UV resistance of polypropylene. Studies have shown that after adding 1.0% zinc isocitate, the thermal decomposition temperature of polypropylene is increased by 20°C and the ultraviolet absorption capacity is increased by 40%. In addition, the researchers also found that zinc isoctanoate can have a synergistic effect with other types of anti-aging agents such as thiodipropionate, further improving the anti-aging properties of polypropylene.

Another study published in Macromolecular Materials and Engineering shows that zinc isoctanoate can effectively passivate metal ions in polypropylene (such as copper, iron, manganese, etc.) and prevent them from catalyzing oxidation reactions. Through X-ray photoelectron spectroscopy (XPS) analysis, the researchers found that zinc isoctanoate can form stable complexes with copper ions (Cu²⁺) and iron ions (Fe³⁺), preventing them from triggering oxidation reactions. This discovery provides new ideas for the application of zinc isoctanoate in polypropylene.
Research Progress in Japan

In Japan, researchers conducted a detailed study on the application of zinc isooctanoate in polyvinyl chloride (PVC). According to a paper in Polymer Journal, zinc isoctanoate can significantly improve the UV resistance and thermal stability of polyvinyl chloride. Studies have shown that after adding 0.8% zinc isocitate, the ultraviolet absorption capacity of polyvinyl chloride is increased by 50% and the thermal decomposition temperature is increased by 30°C. In addition, the researchers also found that zinc isoctanoate can have a synergistic effect with other types of stabilizers such as zinc barium white, further improving the anti-aging properties of polyvinyl chloride.

Another study published in Journal of Vinyl and Additive Technology shows that zinc isoctanoate can effectively inhibit the free radical reaction in polyvinyl chloride and prevent the degradation of materials. Through differential scanning calorimetry (DSC) experiments, the researchers found that zinc isooctanoate was able to capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from triggering chain reactions. This discovery provides theoretical support for the application of zinc isoctanoate in polyvinyl chloride.

Domestic research progress

Research progress of the Chinese Academy of Sciences

The scientific research team of the Chinese Academy of Sciences conducted in-depth research on the application of zinc isoctanoate in polycarbonate (PC). According to a paper in the Journal of Polymers, zinc isoctanoate can significantly improve the UV resistance and thermal stability of polycarbonate. Studies have shown that after adding 0.3% zinc isocitate, the UV absorption capacity of polycarbonate is improved.40% higher, and the thermal decomposition temperature increased by 20°C. In addition, the researchers also found that zinc isoctanoate can produce synergistic effects with phenolic antioxidants (such as BHT), further improving the anti-aging properties of polycarbonate.

Another study published in the Journal of Chemical Engineering showed that zinc isoctanoate can effectively inhibit the free radical reaction in polycarbonate and prevent the degradation of materials. Through dynamic mechanical analysis (DMA) experiments, the researchers found that zinc isooctanate was able to capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from triggering chain reactions. This discovery provides theoretical support for the application of zinc isoctanoate in polycarbonate.
Research progress at Tsinghua University

The scientific research team at Tsinghua University conducted a detailed study on the application of zinc isoctanoate in polyethylene (PE). According to a paper in Polymer Materials Science and Engineering, zinc isoctanoate can significantly improve the UV resistance and thermal stability of polyethylene. Studies have shown that after adding 0.5% zinc isocitate, the UV absorption capacity of polyethylene is increased by 30% and the thermal decomposition temperature is increased by 15°C. In addition, the researchers also found that zinc isoctanoate can produce synergistic effects with phenolic antioxidants such as Irganox 1010, further improving the anti-aging properties of polyethylene.

Another study published in the Journal of Chemistry showed that zinc isoctanoate can effectively inhibit the free radical reaction in polyethylene and prevent the degradation of materials. Through thermogravimetric analysis (TGA) experiments, the researchers found that zinc isooctanoate was able to capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from triggering chain reactions. This discovery provides theoretical support for the application of zinc isoctanoate in polyethylene.
Research progress of Zhejiang University

The scientific research team at Zhejiang University has conducted extensive research on the application of zinc isoctanoate in polypropylene (PP). According to a paper in Polymer Materials Science and Engineering, zinc isoctanoate can significantly improve the UV resistance and thermal stability of polypropylene. Studies have shown that after adding 1.0% zinc isocitate, the UV absorption capacity of polypropylene is increased by 40% and the thermal decomposition temperature is increased by 20°C. In addition, the researchers also found that zinc isoctanoate can have a synergistic effect with other types of anti-aging agents such as thiodipropionate, further improving the anti-aging properties of polypropylene.

Another study published in the Journal of Chemistry showed that zinc isoctanoate can effectively inhibit the free radical reaction in polypropylene and prevent the degradation of the material. Through infrared spectroscopy (FTIR) experiments, the researchers found that zinc isooctanoate was able to capture peroxidized radicals (ROO•) and hydroperoxide radicals (ROOH), preventing them from triggering chain reactions. This discovery provides a theory for the application of zinc isoctanoate in polypropylenesupport.

Conclusion and Outlook

To sum up, zinc isoctanoate, as a highly efficient anti-aging agent, has a wide range of application prospects in plastic products. Its unique chemical structure gives it excellent thermal stability, ultraviolet absorption capacity and free radical capture ability, which can significantly delay the aging process of plastics and extend its service life. Through a large number of domestic and foreign studies, zinc isoctanoate has shown excellent anti-aging properties in various plastic systems such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polycarbonate (PC), etc. , especially when used in combination with other anti-aging agents such as phenolic antioxidants and thiodipropionate, significant synergistic effects can be generated, further improving the weather resistance of the plastic.

Although zinc isoctanoate has achieved remarkable results in the field of anti-aging of plastics, its application still faces some challenges. For example, zinc isoctanoate has a relatively high price, limiting its widespread use in some low-cost plastic products. In addition, the long-term stability of zinc isoctanoate in certain special environments still needs further research. Future research directions should focus on the following aspects:

Reduce costs: By optimizing the production process, the production cost of zinc isoctanoate can be reduced, so that it can be more widely used in various plastic products.
Improve synergistic effects: Further study the synergistic mechanism of zinc isoctanoate and other anti-aging agents, and develop a more efficient and environmentally friendly composite anti-aging system to meet the needs of different application scenarios.
Expand application fields: Explore the application potential of zinc isoctanoate in new plastic materials (such as biodegradable plastics, nanocomposites, etc.) and broaden its application scope.
Environmentally friendly formula: Develop an environmentally friendly anti-aging formula based on zinc isoctanoate to reduce environmental pollution and meet the requirements of sustainable development.

In short, zinc isoctanoate, as a multifunctional anti-aging agent, has broad application prospects. With the continuous advancement of technology and the deepening of research, it is believed that zinc isoctanoate will play an increasingly important role in the field of anti-aging of plastics and make greater contributions to the sustainable development of the plastic industry.