As people increasingly favor environmentally friendly packaging, the demand for degradable materials is increasing. People are starting to find and develop some sustainable or eco-friendly environmentally friendly materials. Biodegradable plastics are one of the most environmentally friendly and promising green materials. Biodegradable bag supplier:
Under specified environmental conditions, after a period of time and including one or more steps, significant changes in the material's chemical structure result in loss of certain properties (such as integrity, molecular weight, structure, or mechanical strength) and / or plastic that has broken. Tests should be performed using standard test methods that reflect changes in performance, and their categories should be determined according to the degradation method and the life cycle. Degradable plastics are divided into biodegradable plastics, compostable plastics, photodegradable plastics, and thermal oxygen-degradable plastics according to their designed final degradation pathways.
Degradation in nature such as soil and / or sand, and / or specific conditions such as composting or anaerobic digestion or in aqueous culture medium, caused by the action of microorganisms such as bacteria, molds and seaweeds that are present in nature And finally completely degraded into carbon dioxide (CO2) or / and methane (CH4), water (H2O) and mineralized inorganic salts of the elements it contains and new biomass plastics. Also known as biodegradable plastic.
Biodegradable plastics classification: according to the composition of raw materials and manufacturing processes can be divided into the following three: natural polymers and their modified materials, microbial synthetic polymer materials and chemically synthesized polymer materials.
The currently used biodegradable plastics are: poly-3-hydroxyalkanoate (PHA), polylactic acid (PLA), polyε-caprolactone (PCL), and polybutylene succinate (PBS).
Poly 3-hydroxyalkanoate (PHA):
Polyhydroxy fatty acid esters are aliphatic copolyesters of different structures synthesized by microorganisms through various carbon sources. The most common are poly 3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV), and copolymers of PHB and PHV (PHBV). PHB is a thermoplastic polyester widely found in nature, especially found in bacterial cells. Many physical and mechanical properties of PHB are close to those of polypropylene plastic, but it is biodegradable and biocompatible, and can be completely degraded into β-hydroxybutyric acid, carbon dioxide and water in the body. Materials made with this bioplastic can be used in drug release systems, implants, and some devices that harmlessly decompose in the human body after healing, but PHB is harder and more brittle than polypropylene. The copolymerization of PHB and PHV (PHBV) can improve the weak point of high crystallinity and brittleness of PHB, and improve its mechanical properties, heat resistance and water resistance. The PHB / PHV copolymer is already available under the trade name Biopol. Biopol is composed of a series of different materials. When the PHV content is up to 30% and the PHB / PHV is 89/11, the strength and toughness of the copolymer are the best. Such products can be used in food packaging, cosmetics, medicine , Health and agriculture industries.
Polyε-caprolactone (PCL) is a low-melting polymer obtained by ring-opening polymerization of ε-caprolactone, and its melting point is only 62 ° C. PCL degradability has been studied since 1976. PCL can be completely decomposed by microorganisms in both anaerobic and aerobic environments. Compared with PLA, PCL has better hydrophobicity but slower degradation rate; meanwhile, its synthesis process is simple and the cost is lower. PCL has excellent processing performance and can be made into films and other products with ordinary plastic processing equipment. At the same time, PCL and a variety of polymers have good compatibility, such as PE, PP, PVA, ABS, rubber, cellulose and starch, etc., through blending and copolymerization can obtain materials with excellent performance. Especially the blending or copolymerization with starch can keep its biodegradability and reduce the cost, so it has attracted much attention. PCL can be blended with starch to obtain degradable plastics with good water resistance. The price is similar to that of paper. Using in-situ polymerization, ε-caprolactone can be grafted with starch to obtain thermoplastic polymers with excellent properties.