Study Of The Rigid Polyvinyl Chloride Foaming Material

The foam plastics have been widely applied in numerious fields of people’s dailylives and industrial manufacturing because of the outstanding performances inlow-density, sound insulation, heat insulation, high specific strength and so on.Nevertheless, the shortcoming of most foam plastics is flammable, which could causefire disasters easily and a serious threat to the people’s health and property. Polyvinylchloride (PVC) has been widely used in construction, chemical, electrical, andpackaging industry due to its excellent flame-retardance property, excellentcorrosion-resistance, high mechanical strength, richness of raw materials andoutstanding forming ability and so forth. PVC resin could reach a relatively highoxygen index without any modification. Thus, developing environmental-friendly PVCfoam with low-density, high strength has become the focus in this field. In this paper,the study on rigid polyvinyl chloride (R-PVC) foam material are carried out as follows:Firstly, A novel kind of composite foaming agents for rigid PVC(R-PVC) wasprepared from modifying azodicarbonamide (AC) with kickers and sodium bicarbonate.The samples were analysed with thermal analysis and gas volume test. The resultsindicate that the novel composite foaming agent with a mass ratio of10︰10︰2.5︰2.5, which represent AC, carbamide, zinc carbonate and sodium bicarbonaterespectively, poses optimized properties: its decomposition temperature lies within thetemperature range suitable for R-PVC processing, its endotherm equals exotherm onthe whole and this composite foaming agent has a high volume of liberated gas butwithout any abruptness. R-PVC foam manufactured with this composite foaming agenthas better mechanical properties, and its SEM images present fine microcellularstructure.Secondly, taking advantage of the synergistic effect of zincstearate(ZnSt2)/calcium stearate(CaSt2) and auxiliary heat stabilizer, the compositeheat stabilizer was prepared by ball milling mixed compound method. The compositeheat stabilizer was characterized in aspects of PVC’s initial coloration performanceand long-term thermal stability by oven method. The results show that the thermalstability of composite heat stabilizer modified PVC achieved best when the mass ratioof ZnSt2, CaSt2, pentaerythritol, epoxidized soybean oil, antioxidant1010is2.8︰1.2︰1︰0.5︰0.3. Compared with the conventional heat stabilizer (tribasic lead sulfate),the utilization of the composite heat stabilizer could improve PVC resin’s initial colorability by10%, the long-term thermal stability could be up to90%.Finally, R-PVC foam material was prepared with the composite foaming agent,the composite heat stabilizer, active nano-CaCO3, lubricants, solvents and otheradditives via molding foaming. And effects of various additives and processingconditions on the performances of R-PVC foam material were investigated, then thematerials formulation and processing conditions for preparation of R-PVC foammaterial were achieved. When the mass ratio of PVC resin is100%, compositefoaming agent is8%, the composite heat stabilizer is4%, modified nano-CaCO3is2%,glyceryl monostearate is1%and dichloromethane is40%, PVC foam materials withbest comprehensive performance were achieveed under the conditions of10minsmolding heating for10mins, boiling10mins and baking for4days. In this conditions,the density is80kg/m3, the hardness is43.1, tensile strength is1.493MPa, thecompressive strength is0.451Mpa.