The foaming material of /VAC) is a foamed plastic having a microporous inside as an EVAC resin. The presence of gas phase makes EVAC foam materials have the advantages of low density, high specific strength, absorption load, heat insulation, sound insulation, etc., as well as good aging resistance and chemical corrosion resistance, so they are widely used in seat cushions, foam flooring, Life-saving materials and shoe materials have been greatly developed in recent years. However, its tear strength and peel strength are not good enough to limit its application. For example, some well-known sports shoes have strict requirements on these properties. Therefore, it is often necessary to blend EVAC with a resin or a rubber to improve the mechanical strength of the foamed material.
Commonly used blending modifiers are low density polyethylene (LDPE) 1121 and (ethylene propylene diene macropolymer (EPDM) 131, etc. I have used a new type of polymer A and compatibilizer B to co-exist with EVAC. Blending the blend, it is hoped that the mechanical strength of the foamed material will be improved. Because it is a new type of material, it is still unknown whether the blend of the composition can obtain the foamed material with good performance. The amount of blowing agent, crosslinker used is not clear about the size of the effect of the blend.
Under certain temperature and pressure, the authors used cross-linked dicumyl peroxide (DCP) to initiate cross-linking of the blending system, while the foaming agent azodicarbonamide (AC) was produced by cross-linking decomposition at the same time of cross-linking. The gas is uniformly filled therein to form a uniform closed pore structure. Finally, EVAC cross-linked foamed material with low density, light weight and good performance is produced.
The author first investigated the properties of the blend matrix with different compositions and compared it with the corresponding foaming materials, which has certain guiding significance for the selection of matrix. The effects of different DCP and AC dosages on various properties of foamed materials were also investigated.
Base Formula No. Density 035g Shore C Hardness Peel Strength / Shore C Hardness Peel Strength / Shore C Hardness Peel Strength / As can be seen from Table 4, the foaming material with a small amount of modifier A has a low hardness, and the matrix The change in mechanical properties shows the same trend. In particular, the modifier A has 5 parts and the compatibilizer B has 15 parts of the 6 matrix. The hardness after foaming is generally smaller than that of the other substrates. In terms of peel strength, the addition of modifier A will be improved compared with pure EVAC, but the peeling strength of the 5 matrix after curing of modifier A is 625 parts and compatibilizer B is 13.25 parts. Be slow after soaking. The reason is that this ratio is not a good compatible system, resulting in more defects in the foamed material, uneven foaming, and reduced peel strength.
Effect of the amount of 23DCP on the properties of foamed materials DCP is a kind of peroxide, which is used for the purpose of initiating vulcanization and cross-linking by thermal decomposition into free radicals, and is widely used in the crosslinking of various foaming materials. Studies have shown that the amount of DCP has a greater impact on the density and properties of the foamed material. 14' In order to obtain the foamed material of the required density and performance, the amount of the fixed matrix and the blowing agent only changed the amount of DCP, and the amount of DCP was investigated for foaming. The impact of material properties. In the range of DCP dosage of the experiment, uniform foaming materials can be obtained, the cells are fine, the surface is smooth and tidy, no obvious defects, and there is no phenomenon that the foaming material becomes brittle and the surface is cracked due to the excessive amount of DCP, and there is no cause. Insufficient cross-linking causes the cells to rupture. Table 5 lists the effect of DCP dosage on the properties of the foamed material.
Table 5 Effect of the amount of DCP on the properties of the foamed material Matrix Formula No. Density / Elastic Shore C Hardness Peel Strength / As can be seen from Table 5, as the amount of DCP increases, the density of the foamed material gradually becomes larger. This is because the increase in the amount of DCP increases the degree of crosslinking of the system, thereby increasing the viscosity of the molten system, resulting in more difficult foaming, and the generated bubbles are less likely to grow and become larger. As the density increases, the hardness and peel strength of the foamed material also increase, which is consistent with the previous conclusions. Since the amount of the crosslinking agent is too large or too small, the elasticity of the foaming material may be increased first and then decreased as the amount of DCP is increased. At the same density level, the hardness of the 4-base foam after foaming is greater than 6 matrix, and the peel strength is equivalent. This also affects the performance of the foamed material with the amount of 24AC obtained before. The foaming agent AC has a large amount of gas, cheap, and decomposed. It mainly produces nitrogen, non-toxic, odorless and non-polluting. It is suitable for resins such as PE, EVAC, polypropylene (PP), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS). Pressurized and pressurized foaming is a widely used chemical foaming agent. The amount of blowing agent is the main factor controlling the performance of the foaming material, which directly affects the expansion ratio of the material and has a great influence on the physical and mechanical properties of the foamed material. When the foaming agent is excessive, more large pores will be formed inside the foamed material, and the tensile strength, tear strength, peel strength, elasticity and adhesion of the foamed material will be deteriorated, and even the bubble may be caused to expand. Cracking and foaming unsuccessful results; when the amount of foaming agent is too small, the matrix foaming is not normal, it is obvious that the foaming is insufficient, and the performance of the matrix is ​​not improved. 61. Table 6 lists the AC dosage. The effect of foam material properties.
Table 6 Effect of AC Amount on Properties of Foamed Materials Base Formula No. AC Part Density / Elastic Shore C Hardness Peel Strength / As can be seen from Table 6, with the amount of crosslinking agent unchanged, with the amount of blowing agent With the increase, the density of the foamed material gradually decreases. The reason is that in the case where the degree of crosslinking is similar, the increase of the blowing agent means an increase in the amount of gas generated, which inevitably leads to foaming when it is ensured that no gas escapes and all the generated gas will be completely enclosed in the foaming material. The increase in magnification, the decrease in density, and the decrease in density, the hardness and peel strength also decrease. This is consistent with the previous conclusions. On the other hand, the elasticity of the foamed material increases with the addition of the amount of the foaming agent, which is mainly due to the elasticity of the foamed material. 1 In the bubble enclosed inside the foamed material, the bubble is deformed when the foamed material is stressed, and the elastic force is generated when the bubble is recovered. In the case of a good degree of cross-linking, the more gas is generated, the more gas is entrapped in the substrate, and the greater the elasticity. The increase in the amount of the blowing agent inevitably leads to an increase in the amount of gas generated, so that the elasticity of the foamed material is improved.
3 Conclusion Modifier A can improve the mechanical properties of EVAC, but the mechanical properties of the matrix will decrease with the increase of the amount of compatibilizer B. In the case where the ratio of the blowing agent to the crosslinking agent is the same, the density of the foaming material obtained by using the blend base of the modifier A is low. It can be seen that the addition of modifier A makes the blend matrix easier to foam.
Studies on foamed materials of similar density obtained from different substrates show that the properties of the matrix are consistent with certain properties of the foamed material. At a suitable ratio, the addition of modifier A increases the peel strength of the foamed material and, at certain ratios, reduces the hardness of the foamed material.
By investigating the effects of different amounts of cross-linking agent DCP and blowing agent AC on the properties of foamed materials, it was found that the increase in the amount of DCP increased the density of the foamed material, accompanied by an increase in the hardness and peel strength of the foamed material. The elasticity first increases and then decreases as the amount of DCP increases. The increase in the amount of AC causes the density of the foamed material to decrease, accompanied by a decrease in the hardness and peel strength of the foamed material; the elasticity increases as the amount of AC increases.
(Finish)
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