1. Is the toughening effect of the toughening agent good?
The main function of the toughening agent is to increase the toughness. Generally, after adding it, it can reduce the brittleness of the composite material and improve the resistance of the composite material. Impact performance.
Ordinary toughening agents simply absorb energy and are not integrated with the material, so the toughening effect is relatively average; good toughening agents are elastomers plus a graft-compatible system, which can transmit energy more effectively. , improves the impact strength, has a significant toughening effect, has strong polarity and high tensile strength, and has no major impact on the strength and modulus of the material.
2. How is the toughening effect of plastic toughening agents affected?
Toughening agents added to plastics can increase the toughness of plastics. Different toughening agents and different types of plastics have different toughening effects. Generally, the toughening effect of toughening agents is mainly affected by the following factors. Influence of The toughness of the matrix resin can be achieved by: increasing the molecular weight of the matrix resin to narrow the molecular weight distribution; improving toughness by controlling whether to crystallize, the degree of crystallization, crystal size and crystal form, etc. For example, adding nucleating agents to PP increases the crystallization rate and refines the grains, thereby improving fracture toughness.
2. Characteristics and dosage of toughening agent
(1) Influence of the particle size of the dispersed phase of toughening agent: For elastomer-toughened plastics, Depending on the characteristics of the matrix resin, the optimal value of the elastomer dispersed phase particle size is also different. For example, the optimal particle size of rubber in HIPS is 0.8 to 1.3 μm, the optimal particle size in ABS is about 0.3 μm, and the optimal particle size in PVC-modified ABS is about 0.1 μm.
(2) Influence of the amount of toughening agent: There is an optimal value for the amount of toughening agent, which is related to the particle spacing parameter.
(3) The influence of the glass transition temperature of the toughening agent: Generally, the lower the glass transition temperature of the elastomer, the better the toughening effect.
(4) The influence of the interface strength between the toughening agent and the matrix resin: Different systems have different effects of the interface bonding strength on the toughening effect.
(5) The influence of elastomer toughening agent structure: related to elastomer type, cross-linking degree, etc.
3, The bonding force between the two phases
The two phases have good bonding force, which can effectively transmit stress between the phases and consume more energy. Macroscopically, the comprehensive performance of plastics The better, especially the improvement in impact strength is the most significant. Usually this binding force can be understood as the interaction force between the two phases. Graft copolymerization and block copolymerization are typical methods to increase the binding force of the two phases. The difference is that they form chemical bonds through chemical synthesis methods, such as graft copolymerization and block copolymerization. Branch copolymer HIPS, ABS, block copolymer SBS, polyurethane.
For plastics toughened by toughening agents, it is a physical blending method. An ideal blend system should be one in which the two components are both partially compatible and in separate phases. There is an interface layer between the phases. In the interface layer, the molecular chains of the two polymers diffuse each other and there is an obvious concentration gradient. By increasing the blending The compatibility between components enables good binding force, thereby enhancing diffusion and dispersing the interface, increasing the thickness of the interface layer. And this is the key technology for plastic toughening and preparation of polymer alloys – polymer compatibility technology.
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