Factors affecting the preparation of toughened nylon petfe film production line
DATE：2021/7/30 8:38:26 / READ： / SOURCE：This station
Factors affecting the preparation of toughened nylon petfe film production line
During the preparation of toughened nylon, the type of toughening agent, mixing degree, dispersion and compatibility of elastomer in nylon have a great influence on the toughening effect（ 1) The effect of elastomer on the toughening effect is mainly determined by its own properties and its compatibility with nylon. Different elastomers have different toughening effects on nylon. The toughening effect of grafted Poe and EPDM is the best. Selection principle of elastomer: good compatibility with nylon; The melt flow rate is close to that of nylon, and there is no decomposition at the melt blending temperature. According to the application requirements, multi-component or single component elastomers are used. Petfe film production line www.handern.com(2) Influence of elastomer dosage; The amount of elastomer has a great influence on the mechanical properties of nylon. The results show that the toughening effect is not very obvious when the amount of elastomer is less than 10%. When the content of elastomer is more than 10%, the impact strength of toughened nylon increases greatly, but its tensile and bending strength decreases obviously. It was found that the tensile strength and elastic modulus of PA66 / epdm-g MAH binary blend decreased significantly with the increase of epdm-g-mah content; In PA66 / EPDM / epdm-g-mah system, the decrease of tensile strength and elastic modulus with the increase of epdm-g-mah content is smaller than that of binary system. The elongation of blends increased with the increase of elastomer; For the binary system, the impact strength is directly proportional to the elastomer content; In the ternary system, when the content of epdm-g-mah is less than 10%, the impact strength of the blends increases little with the increase of epdm-g-mah; When the content of epdm-g-mah is more than 10%, the impact strength of the blends increases greatly. For different systems, different elastomers and different nylon matrix, the effects of elastomers are different. Therefore, when determining the amount of elastomer, the needs and requirements of application should be considered. Generally speaking, the elastomer content should not be too high. Otherwise, it solves many problems, such as the decline of toughness and rigidity, as well as surface properties, processing properties, forming shrinkage, deformation and so on. Petfe film production line www.handern.com
(3) The influence of crosslinking degree of elastomer; The elastomer has certain strength and elasticity only after crosslinking. Therefore, the crosslinking degree of elastomer has a great influence on the properties of toughened nylon. It is mainly reflected in impact strength, fluidity, material apparent properties and so on. When the crosslinking is too small, the toughening effect is not very obvious. This is because when the crosslinking degree is small, there are many uncrosslinked macromolecules in the elastomer, and the elastomer with linear structure is easy to deform under the action of external force. This deformation leads to multiple crazes and even cracks in the transition zone between the elastomer and nylon; When the crosslinking is too large, the elasticity will lose fluidity and elasticity, which will have an adverse impact on the toughening effect. At the same time, the surface of highly crosslinked elastomer is irregular concave and convex, resulting in the decline of material surface finish and even loss of luster. Petfe film production line www.handern.com
(4) The influence of elastomer particle size and distribution; Different particle size and distribution have different toughening effects, and different base materials have different requirements for elastomer particle size and distribution. For nylon elastomer, it is more appropriate to control the particle size in the range of 0.2 ~ 0.5um. The control of elastomer particle size is mainly determined by shear strength and dosage. Generally speaking, if the shear strength is large, the particle size is small. But no matter how high the shear strength, it will not break to the molecular state. When the addition amount of elastomer exceeds a certain volume fraction particle size / um, the particle size increases with the increase of dosage. For most blends, the distribution curve of rubber particles in super tough nylon. When the dosage ratio of two components reaches 50:50, the blends appear two-phase continuity. Petfe film production line www.handern.com
(5) The influence of blending mode mainly affects the dispersion of elastomer. In the elastomer grafting and crosslinking system, the blending mode also affects the degree of crosslinking. There are three blending methods.
The so-called two-step method is to prepare thermoplastic elastomer first, that is, complete the crosslinking and grafting of elastomer to make toughened masterbatch, and then blend and extrude the toughened masterbatch with nylon to prepare toughened nylon. The two-step method is conducive to the dispersion of elastomer. At the same time, a small number of unreacted grafted monomers react further in the blending process, which is conducive to improve the compatibility between elastomer and nylon.
2 in situ vulcanization compatibilization method the so-called in situ vulcanization compatibilization is that the process of crosslinking, grafting and nylon blending is completed at one time in the twin-screw extruder, that is, elastomer, crosslinking agent, initiator, grafted monomer and nylon are mixed and then enter the twin-screw extruder for blending, extrusion and granulation. The blending process is simple, but there are certain requirements for the screw structure, that is, the materials are required to be fully mixed in the twin-screw extruder. Otherwise, it will have a certain impact on the dispersion of elastomer, and it is likely to produce local uneven concentration.
3 second-order blending method second-order blending method is to blend and extrude the blend twice in twin-screw. In this method, the elastomer is evenly dispersed and the product performance is uniform, but it should be noted that for nylon prone to thermal degradation or nylon prone to hydrolysis, its performance is likely to be affected. Petfe film production line www.handern.com
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