Mechanical properties and crosslink density of rare earth‐modified high‐abrasion furnace‐filled powdered natural rubber

High‐abrasion furnace‐filled powdered natural rubber [P(NR/HAF)] has more advantages than traditional HAF‐filled bale NR (NR/HAF) because of its better environmental performance and easier processing quality, but its lower mechanical properties are disadvantageous. To improve the mechanical properties, rare earth‐modified HAF‐filled powdered NR [P(NR/HAF‐Ln)] (Ln = Sm,La,Pr) was prepared by means of coacervation–coprecipitation, using rare earth‐modified HAF as separant and filler. The effect on mechanical properties of P(NR/HAF‐Ln) vulcanizate exerted by the emulsifier/HAF ratio, powdering temperature, Ln/HAF ratio and type of Ln, and HAF content were studied. The results indicated that when optimum formulation, the mechanical properties of P(NR/HAF‐Ln) vulcanizate were better than P(NR/HAF) vulcanizate. In addition, the relationship of the apparent crosslink density and HAF content of P(NR/HAF‐Ln), P(NR/HAF), NR/HAF vulcanizates was also investigated, along with their SEM microphotographs of tensile fracture surface, which indicated that the excellent mechanical properties of P(NR/HAF‐Ln) vulcanizate was attributed to correct amount of Ln that could increase crosslink density and reinforce the interface structure of NR matrix/HAF‐Ln particle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1755–1762, 2006     

Hydrogenation of natural rubber latex in the presence of OsHCl(CO)(O2)(PCy3)2

Hydrogenation is an important method of chemical modification, which improves the physical, chemical, and thermal properties of diene elastomers. Natural rubber latex (NRL) can be quantitatively hydrogenated to provide a strictly alternating ethylene–propylene copolymer using a homogeneous osmium catalyst OsHCl(CO)(O₂)(PCy₃)₂. A detailed kinetic investigation was carried out by monitoring the amount of hydrogen consumption during the reaction using a gas‐uptake apparatus. The kinetic results of NRL hydrogenation indicated that this system had a second‐order dependence of the hydrogenation rate on hydrogen pressure and then decreased toward a zero‐order dependence for hydrogen pressures above 13.8 bar. The hydrogenation was also observed to be first‐order with respect to catalyst concentration and inverse first‐order on rubber concentration due to impurities present in the rubber latex. Additions of a controlled amount of acid demonstrated a beneficial effect on the hydrogenation rate of NRL. The temperature dependence of the hydrogenation rate was investigated and an apparent activation energy (over the range of 120–160°C) was calculated as 57.6 kJ/mol. Mechanistic aspects of this catalytic process are discussed on the basis of kinetic results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 640–655, 2006     

混炼硅橡胶的配合技术(四)

介绍了几种胶辊用混炼硅橡胶的配制,包括低硬度胶辊用混炼硅橡胶、低环硅氧烷含量的胶辊用混炼硅橡胶、送纸胶辊用混炼硅橡胶及工业胶辊用混炼硅橡胶的配制。     

湿磨绢云母粉在天然橡胶和丁苯橡胶中的应用

介绍了湿磨娟云母粉在天然橡胶和丁苯橡胶中的应用试验，结果表明，湿磨绢云母粉具有补强性能。作为一种补强填充剂，湿磨绢云母粉应用在橡胶中具有性能价格比优势。     

橡胶对HIPS树脂落锤指标的影响

通过对高抗冲聚苯乙烯树脂出现产品落锤指标偏低问题的分析，从橡胶配量及其粒径大小上进行了改进，同时改进了工艺操作，采取了提高反应釜搅拌速度、降低乙苯浓度等措施。结果产品合格率达到９９％以上，优级品率达到９８％以上。     

Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler

The influence of the electron beam modification of a dual‐phase filler on the dynamic mechanical properties of styrene‐butadiene rubber (SBR) is investigated in the presence and absence of trimethylol propane triacrylate or triethoxysilylpropyltetrasulfide. Electron beam modification of the filler results in reduction of the tan δ at 70°C, a parameter for rolling resistance, and an increase in the tan δ at 0°C, a parameter for wet skid resistance of SBR vulcanizates. These modified fillers give significantly better overall performance in comparison with the control dual‐phase filler. This variation in properties is explained in terms of filler parameters such as the filler structure that leads to rubber occlusion and filler networking. These results are further corroborated using the master curves obtained by the time–temperature superposition principle. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2992–3004, 2003     

冷冻凝聚工艺生产CR322的研制

对原电解质凝聚工艺生产CR322(混合调节型氯丁橡胶)进行了改进，实现了冷冻凝聚新工艺法生产切块CR322，即主乳化剂由松香皂／脂肪酸皂复合型代替了单一松香皂。新工艺解决了冷冻转鼓装置生产CR322过程中“黏杆”及干胶门尼黏度控制等问题。产品无焦烧粒子。且焦烧时间明显延长。     

PVC╱NBR╱BR三元共混弹性体的制备

采用结合丙烯腈含量为26％的NBR、分子量适中的悬浮法Ⅲ型PVC和BR共混,制得了综合性能较PVC/NBR并用胶优异的弹性体。优选的工艺条件为:PVC/NBR/BR=30/60/10(质量比);补强剂选用炭黑40份,超细碳酸钙50份,轻质碳酸钙20份;硫化体系选用过氧化物加少量硫磺;混炼温度为140—170℃,混炼时间为10—15min。通过电子显微镜和动态力学分析,弹性体存在两个T,PVC为分散相,橡胶为连续相。