Recycled plastics have become an effective social resource. Recycled plastic components are often blended together with two or more different materials. These materials can be used to produce a variety of plastic products. The modification of plastics is another step beyond the polymerization process to gain new properties. A simple and effective method of resin.
The modified synthetic material not only has a simple process, a low cost, and excellent performance, thereby expanding the application field of synthetic resins. The use of blended modification technology to achieve high performance, versatility, and refinement of recycled plastics is More scientific and practical new technology.
PVC has many excellent properties, and its application is also very extensive, but it also has obvious disadvantages such as low softening point, heat resistance, poor cold resistance, easy decomposition, poor thermal stability, etc. To improve its shortcomings, some polychlorinated chlorines appeared. Modified varieties of ethylene.
Blending modification of recycled PVC
PVC/CPE Blend Modification
Polyvinyl chloride and polyethylene are very versatile plastics, occupying a large proportion of waste plastics, and are often difficult to sort when recycling used plastics. CPE is a product of polyethylene after chlorination. Chlorine content is 25 % ~ 40% of CPE has the properties of elastomers. CPE can act as a compatibilizer between PVC and PE, which can improve the properties of the blends. Recycling of PVC and PE recycled plastics It makes sense.
In addition, CPE can also be added to PVC hard products, mainly to play a role in toughening modification. CPE with a chlorine content of 36% is commonly used as a toughening modifier for PVC.
PVC/MBS blend modification
MBS is a grafted blend of methyl methacrylate (MMA) and styrene (ST) grafted onto polybutadiene (PB) or styrene-butadiene rubber (SBR) macromolecular chains.
MBS resin has good compatibility with polyvinyl chloride, can significantly improve the impact strength of PVC, and can also improve the processing performance of PVC, PVC/MBS blends also have a good transparency, so MBS It is widely used in the toughening and modification of rigid polyvinyl chloride, especially in transparent products.
PVC/EVA Blend Modification
EVA is a random copolymer of ethylene and vinyl acetate. Polyvinyl chloride and EVA are blended and modified. EVA can be used for the toughening modification of rigid polyvinyl chloride. It can also be used for soft polyvinyl chloride. Rigid PVC/ EVA blends can be used to produce plates and profiles, as well as low foam products.
The use of EVA in soft polyvinyl chloride can significantly improve the cold resistance of PVC. The embrittlement temperature of this PVC/EVA blend can reach -70°C. In addition, the soft PVC/EVA blend also has Good hand feel. Soft PVC/EVA blends can be used to produce cold films, sheets, artificial leather, etc., as well as foam products.
PVC/ABS blending modification
ABS is an acrylonitrile butadiene-styrene copolymer, with high impact properties, easy molding, good handfeel and easy plating characteristics. Blending PVC and ABS, can combine the advantages of both, become Electrical enclosures, electrical components, automotive dashboards, textile equipment, luggage, etc. have a wide range of new materials.
ABS can be used as toughening modifiers for hard PVC, and processing fluidity is also significantly improved. Due to the moderate compatibility between PVC and ABS, compatibilizers should be added during blending. Such as CPE, SAN, etc. After adding compatibilizer CPE in ABS/PVC blend system, the impact strength of the blend system can be significantly improved. In addition, due to ABS containing unsaturated double bonds, its thermal stability and antioxidant properties, etc. Lower, so in addition to adding heat stabilizer in the formula, it should also add antioxidants.
The blending of ABS with polyvinyl chloride can also significantly improve the flame retardant properties of ABS. This feature makes ABS/PVC blends suitable for use in the manufacture of electrical enclosures and components, avoiding the performance degradation and help caused by the addition of small molecular flame retardants. Disadvantages of the agent precipitation. In the PVC/ABS blend system can also add appropriate plasticizers to become semi-hard products, can be used to manufacture car dashboard.
PVC/TPU Blend Modification
Polyvinyl chloride and thermoplastic polyurethane blends have been modified to become a new type of thermoplastic elastomer, also known as polyurethane rubber. Polyurethane has excellent physical and chemical properties and excellent biocompatibility. The TPU and polyvinyl chloride together Blended with TPU instead of DOP and other liquid plasticizers to make soft PVC medical products to avoid migration of liquid plasticizers. In PVC/TPU blend systems, reinforcing agents can be added to improve the mechanical properties A variety of reinforcing agents, silica (silica) reinforcing effect is better. Polyvinyl chloride heat stabilizer can use calcium stearate and so on.
TPU can also be used in PVC hard products as a toughening agent for PVC to prepare PVC/TPU blend toughening materials.
Different types of PVC blends
The blending modification of polyvinyl chloride not only includes the blending of polyvinyl chloride and other polymers, but also includes the blending of different types of polyvinyl chloride.
High degree of polymerization of polyvinyl chloride and ordinary PVC blend. High degree of polymerization of polyvinyl chloride resin (HPVC) refers to the degree of polymerization of polyvinyl chloride resin greater than 2000. HPVC can be used to manufacture PVC thermoplastic elastomer. But due to polymerization High degree, HPVC processing molding has certain difficulties. Blending HPVC with common PVC can improve the processing flow of HPVC.
For ordinary PVC, HPVC can be considered as a modifier, which can improve the performance of ordinary PVC. HPVC plasticizer capacity higher than ordinary PVC, in the HPVC / PVC blend In the system, more plasticizers can be added to improve the cold resistance and elasticity of the products. Here HPVC plays a role similar to nitrile rubber. For example, adding more than 20 pieces of HPVC into soft polyvinyl chloride films, products Flexible, with good low temperature flexibility.