Study On Morphologies, Structures And Properties Of Polystyrene Composites

Preparation of polymer composites by blending a polymer with an elastomeror filler is one of the important methods to realize high performance of polymermaterials. It is feasible in Plastics Industry because of low cost and short period ofdevelopment. Deep investigation and analysis on high performance, applicationand theory of Polystyrene composites were carried out. A lot of valuableinformation was obtained that can be used for development of Polystyrenecomposites. The main works and conclusions were listed as following: 1 Calcium carbonate in micrometer, glass beads and talc are toughnessmodifier for Polystyrene at low contents. For example, the Izod impact strength ofthe PS blend with CaCO3 (2 PHR) is 42% higher than that of PS, and with talc,58%. The dispersion of nano-CaCO3 in PS is an important factor for preparationof PS/nano-CaCO3 blends. The PS/nano-SiO2 blends have the worst Izod impactstrengths than that of PS if the dispersion in PS of nano-SiO2 is not uniform. Theagglomerated particles of a nano-filler in a polymer matrix will impair themechanical properties of the polymer blend with them. 2. The mechanical properties of PS blend with nano-CaCO3 (pretreated bystearic acid) increase with the increase of the contents of surface-active agent. TheIzod impact strength and tensile strength of PS/nano-CaCO3 (10 PHR, pretreated IV四川大学博士学位论文by 5 PHR stearic acid) blend are 39%,9% higher than those of a pure PSrespectively. Generally speaking, the tensile strength of a polymer blend withfiller will decrease with the increase of the content of filler. Why can nano-CaCO3(pretreated by stearic acid) improve the tensile strength of PS blend? Themulti-crazing, occurring in PS/nano-CaCO3 blend, will elongate its sample tomore extent than PS sample. A part in the surface normal to the direction of tensileload, remaining at elastic stage, will withstand more loads. So the tensile strengthof the blend sample will increase because of the larger elongation of it. 3. SBS is the better toughness modifier of PS than POE, EPDM and BRbecause the PS domains in SBS are partly compatible with PS. The Izod strengthof PS blend with 33.3 wt% SBS is 11.6 times more than that of PS. Theelongation at break of PS blend with the same content of SBS and POE, is higherthan those of PS blends with POE and SBS at the same content of elastomer (20PHR) respectively, though the Izod impact strength of it is lower than that of PSblend with SBS. It is feasible for the 'relative stress drop' to estimate the Izodstrengths of some PS blends. The values of Tg of PS blends with SBS are higherthan those of PS and the PS domains in SBS. This shows that the PS chain endscould join in the PS domains in SBS. 4. When the contents of filler and elastomer are 10 and 20 PHR respectively,the incorporation of an additive will further increase the Izod impact strength ofthe PS blend by 46%, when 30 and 20 PHR, 73%. The Izod impact strength ofPS/elastomer/filler/additive blend with the same content of SBS and EPDM is66% higher than that of PS/elastomer/filler/additive blend with SBS solely withthe same content of elastomer. 5. The change in structure of a modified material will be responded by theproperties in several aspects. Studying the binary PS blends (PS/SBS) and ternaryPS blends (PS/SBS/CaCO3), we found that several transitions in each of themoccurred simultaneously. The BDT occurs in the two PS blends with the increaseof the contents of SBS. Moreover, the BDT of PS/SBS/CaCO3 advances,comparing with that of PS/SBS. It is interesting that the BDT happens in the izod V聚苯乙烯基复合材料形态,结构与性能的研究impact test, the tensile test and the morphology in the same content range of SBSsimultaneously. In order to distinguish from the single transition, we called itcomplete BDT, and predicted it is a common phenomenon in the mo...