Compatibilization of EVA single layer coextrusion casting film production line
DATE：2021/7/26 8:33:32 / READ： / SOURCE：This station
Compatibilization of EVA single layer coextrusion casting film production line
Adding EVA into PC / PE alloy can reduce the interfacial tension between PC and PE and reduce the size of dispersed phase. With the increase of EVA content, the particle size of dispersed phase decreases. When the EVA content is 1%, the particle size of dispersed phase tends to be constant. Continue to increase the EVA content to 3%, and the particle size of dispersed phase remains unchanged. The compatibilization effect of EVA on PC / PE is also to improve the impact strength of the alloy. When the content of EVA exceeds 5%, the increasing trend of impact strength is not obvious. Single layer coextrusion casting film production line www.handern.comThe biggest feature of EVA is that it can improve the fusion joint strength of PC / PE alloy. Fusion joint strength is a serious problem in plastic processing, especially in injection molding. Fusion joint is usually the area with the weakest mechanical properties in molded products, especially in blends. The fusion joint strength of PC / PE alloy is lower than that of pure PC. adding EVA can make the dispersed particles of PE smaller and more uniform. Adding 1% EVA can increase the fusion joint strength of PC / PE alloy by 3 times. The fusion joint strength of EVA compatibilized PC / PE alloy increases with the increase of injection temperature. This is because the viscosity of the blend decreases with the increase of temperature, which is conducive to the dispersion of EVA. The EVA compatibilized PC / PE alloy was injected into single gate tensile samples without fusion joints and two gate tensile samples with joints respectively. The tensile strength ratio, elastic modulus ratio and elongation ratio of the two samples with different EVA content at different injection temperatures were measured. The results are shown in Figure 5-11. It can be seen from Fig. 5-11 that when the EVA content is about 0.5%, the tensile strength ratio, tensile modulus ratio and elongation ratio of the alloy fusion sample and non fusion sample all reach the maximum. Single layer coextrusion casting film production line www.handern.com
In EVA compatibilized HDPE / PC system, EVA can improve the processing fluidity of the alloy system, but significantly reduce the mechanical properties of the alloy. This is because EVA introduces a short branched chain composed of polar acetic acid groups in the ethylene chain, disrupts the crystalline structure of polyethylene, reduces the crystallinity, increases the distance between macromolecular chains, makes EVA show better flexibility and elasticity than polyethylene, and increases the overall fluidity of the system. At the same time, the fluidity of HDPE / PC Blends without EVA increased first and then decreased with the increase of the number of PC. When adding about 15 parts of PC, the fluidity of the system is the best. The impact strength increases with the increase of EVA content. Because EVA can increase the interfacial force of HDPE / PC, reduce the interfacial tension, make the stress transfer between the two phases better when the material is subjected to external force, and increase the ability of the interface to resist crack propagation, the impact strength of the system is higher than that of the non compatibilized system. However, when the dosage of EVA exceeds 15 parts by mass, the effect is not ideal. Single layer coextrusion casting film production line www.handern.com
Ionomer compatibilizer is a new compatibilizer for PC / PE alloy. It is the product of random copolymer of ethylene and methacrylic acid neutralized by zinc or sodium plasma in varying degrees. This compatibilizer has been commercialized, such as Surlyn 8940 (acrylic acid content 15%, sodium salt neutralization degree 30%) of Dow company, Surlyn 8660 (acrylic acid content 5% ~ 20%) of Du Pont company, Neutralization degree of sodium salt (70%). Surlyrn 8940 can increase the elastic modulus, yield strength and elongation at break of PC / HDPE (80 / 20) alloy, and the above properties reach the maximum when the addition amount is 1%. Single layer coextrusion casting film production line www.handern.com
When ionomer and polyhydroxybisphenol a ether are used in the ratio of 1:1, it has a better compatibilization effect on PC / HDPE alloy. The compatibilization effect of ionomer on PC / PE alloy is related to the content of acrylic acid in ionomer and the degree of sodium ion neutralization. The appropriate content of acrylic acid is 12% ~ 15% and the degree of sodium ion neutralization is 50%. Single layer coextrusion casting film production line www.handern.com
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