Preparation Of NBR Foam And Study On Its Structure And Properties

Currently, NBR foam material less basic research, industry generally rely on theexperience and the large number of experiments to ordered formulations andprocesses. Therefore, we conducted both discussion of the formula of foam material,process and foaming and curing process to the application of basic research, providedstrong support for the industrial production. The main content and results aredescribed as follows:The first part is the preparation of NBR foam material. First by analyzing thedecomposition characteristics of the AC, H,OBSH,NaHCO3-foaming agent, the studyfound that with the separate use of blowing agents, OBSH system have the lowestdensity of those material. When the blowing agent NaHCO3, composite H,AC,OBSH,the density of the foam material did not significantly reduce. Foam products obtainedthe minimum density when the complex of AC and H in accordance with the ratio of2:1. With the increase of the blowing agent, the density of foam products decreases.With high-sulfur low-promoting curing system, the density of foam products was theminimum. With the increase of calcium carbonate, density of foam productsdecreased, and mechanical properties increased.The second part is NBR/PVC foam material. The study found that when theNBR/PVC was70/30ratio, the foam products has the maximum closed-cell ratio,the minimum density, the best mechanical properties. Additionally, density offoaming materials increased with increasing the dosage of sulfur. And, in the lowSulfur high promote system, curing rate can match the foaming speed very well, which generated the best properties of products. In the appropriate curing system, thedensity of foaming materials decreased with the increase of foaming agents. Also,plasticizer (DOP) showed the same effect. The highest obturator rate has been gotwhen the dosage of DOP was30%. However, the filler revealed reverse influenceson the density of products, that is, the usage of filler increased the density.The third part of this paper is the process of the NBR/PVC foam material.Comparison the opened-mixing and the closed-mixing foam, the former’s density istwice of the latter, the mixing process have an greater impact on the foam. Usingmolded foam method, the low-sulfur and low-accelerator vulcanization systemavailable to low-density foam material. The material with free foam method whichused high-sulfur high-accelerator vulcanization system has low-density. In the samevulcanization system, molded foam and free foam methods are not comparable. Thefoam material with static pre-curing can be obtained lower density, also withdynamic pre–curing. The mixing temperature is the most important factor in thepreparation of foam material, with mixing temperature rised, the effect of PVC/NBR blend improved, the dispersion effect reduced, the density of foam materialreduced, the curing scorch period shorter, blend’s hardness increased.Part IV of this paper, some parameters to synthesize the blending foamingmaterials were studied, which include ratio of rubber and plastic, different curingsystems and the dosage of foaming agents. When the ratio of NBR and PVC was50/50, the foaming materials showed the higher obturator rate, the highest bubblediameter and the uniform distribution of the bubble diameter. Molded vulcanizationfoaming and freedom foaming contrast, molding foam is more advantageous to thelow density of products that is because curing speed is far lower than the foam speed.In the appropriate curing system, the density of foaming materials decreased withincrease of foaming agents.