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991.
992.
Rubber aging in tires. Part 1: Field results 总被引:1,自引:0,他引:1
John M. Baldwin David R. Bauer Kevin R. Ellwood 《Polymer Degradation and Stability》2007,92(1):103-109
Oxidative aging of skim and wedge rubber inside the tire results in a loss of peel strength and tensile properties of these rubber materials, which has been found to increase the likelihood of tread separations in certain tires. In order to develop an accelerated laboratory tire aging test, we have carried out extensive field and laboratory studies of rubber property change in tires. This paper describes the analysis of rubber oxidation in a specific set of tires collected from the field. In particular, we determine the rate of property loss under worst-case environmental conditions and analyze the implications of variability in aging results. The analysis is used in a companion paper to develop acceleration factors for different laboratory tests. 相似文献
994.
建立了固相微萃取/气相色谱-质谱联用法(SPME/GC-MS)测定橡胶密封材料中N-亚硝基-N-甲基苯胺(NMPh A)、N-亚硝基-N-乙基苯胺(NEPh A)和N-亚硝基二苯基胺(NDPhe A)3种N-亚硝胺化合物含量的方法。样品参考国标GB/T 24153-2009进行预处理后,采用固相微萃取进行提取,对影响固相微萃取效率的纤维涂覆种类、萃取时间、搅拌速度和萃取温度等条件进行优化。在优化条件下,方法的线性范围为5~500μg/L,相关系数(r)均大于0.99,检出限为0.5μg/kg,回收率为77%~92%,相对标准偏差(RSD,n=6)为3.8%~7.7%。 相似文献
995.
996.
Styrenic polymers and copolymers are often impact modified with rubber particles. The efficiency of rubber toughening depends mainly on the size of the rubber particles and the degree of cross-linking. The deformation rate, the temperature, the orientation of the polymer molecules and the efficiency of rubber grafting also influence rubber toughening. It is thought that on impact, cavitation inside the rubber particles occurs which reduces the detrimental dilatational stress in the bulk polymer without forming cracks in the brittle matrix or at the rubber-matrix interface. Crazing and shearing are facilitated if the rubber particles can easily cavitate. This can be achieved by either avoiding too much cross-linking or by adding oil (silicone oil in the case of ABS) into the rubber particles, which acts as nuclei for void formation. An electron spectroscopic imaging method is described which allows visualizing the location of the oil. Already after cooling silicone oil modified ABS samples down to liquid nitrogen temperature rubber cavitation is observed. This cavitation is caused by the thermal stress developing due to the differences in thermal expansion coefficient between the rubber phase and the SAN-matrix and is facilitated by silicone oil. Voiding also leads to an increase of light scattering, which can be detected by an optical microscope using dark field illumination. 相似文献
997.
A.Z. Niu J. Stellbrink J. Allgaier L. Willner D. Richter B.W. Koenig M. Gondorf S. Willbold L.J. Fetters R.P. May 《Macromolecular Symposia》2004,215(1):1-15
We investigated the anionic polymerization of butadiene in d-heptane solvent using tert-butyl lithium as initiator. Two complementary techniques were used to follow the polymerization processes: 1H NMR and small angle neutron scattering (SANS). The time resolved 1H NMR measurements allowed us to evaluate quantitatively the kinetics of the processes involved. The initiation event commences slowly and then progressively accelerates. This indicates an autocatalytic mechanism. The microstructure of the first monomer units attached is to a high extent 1,2. The disappearance of initiator --- at about 10% monomer conversion --- signals the onset of the normal ∼6% vinyl content of the chain. Small angle neutron scattering was used to study the aggregation behavior of the carbon lithium head groups. It is well known that the polar head groups aggregate and form micellar structures. For dienes in non-polar solvents the textbook mechanism assumes the formation of only tetramers during the propagation reaction. By combining 1H NMR and SANS results we were able to determine quantitatively the aggregation number during all stages of the polymerization. Our measurements show the existence of large-scale structures during the initiation period. The initial degree of aggregation of more than 100 living polymer chains diminished as the polymerization progressed. In addition, even larger, giant structures with Nagg >>1000 and Rg ≈ 1000Å were found. 相似文献
998.
999.
1000.
胶粉/热塑性塑料共混材料的研究 总被引:3,自引:1,他引:2
以胶粉及通用塑料PP和LLDPE为原料,研究了原料种类、相容剂等对胶粉/热塑性塑料共混材料性能的影响,制得了性能较好的共混材料。通过热分析和扫描电镜对制得的共混材料进行分析表征,表明胶粉和LLDPE有较好的相容性及较强的结合力。 相似文献