硫化工艺对EPDM微孔橡胶垫板动静刚度比的影响

研究了硫化三要素及填胶量对EPDM微孔橡胶垫板动静刚度比的影响。结果表明,硫化温度、硫化时间以及硫化压力对橡胶垫板动静刚度比的影响是通过橡胶发泡倍率的变化来体现的,即发泡倍率越大,动静刚度比越小;密度相当时,孔径越小且孔壁越薄,孔数越多,动静刚度比越小。     

低动静刚度比橡胶垫板的研制

从配方设计和硫化工艺参数确定两方面探讨了低动静刚度比橡胶垫板的制备技术。采用动态热力学分析仪研究主体材料、补强剂、硫化剂等配方因素对天然橡胶硫化胶损耗因子(tanδ)的影响。设计了橡胶垫板的低tanδ优化配方。研究了硫化温度、时间、压力等工艺因素对橡胶垫板动静刚度比的影响,确定了合适的硫化工艺参数,制备出具有低动静刚度比特性的橡胶垫板产品。     

测试条件对微孔橡胶垫板动刚度及动静比的影响

建立了微孔橡胶垫板结构简化模型,对动静比与能量损耗的关系进行了定性分析,并考察了测试频率和加载力值对动刚度和动静比的影响。结果表明,在外力作用下,橡胶垫板的内耗越大,则动刚度和动静比越大;随着测试频率和加载力值的增加,动刚度和动静比均增大。     

减振橡胶动静刚度比研究

采用9种不同橡胶,通过标准试样研究了其动静刚度比。结果表明,橡胶大分子链上侧基体积较大、数量多、极性大的橡胶动静刚度较高。天然橡胶并用其他橡胶,其动静刚度比均明显提高。针对5种无机填料,白炭黑的动静刚度比最大,而硅藻土的动静刚度比最小。     

受压与不受压条件对铁路扣件系统减震垫板的静刚度及动静比的长期影响研究

对比研究了长期室外受压与室内不受压存放条件对60-10-17橡胶垫板、WJ7-B橡胶垫板、WJ8-B弹性垫板静刚度及动静比的影响。结果表明,三种试验垫板在室内存储27个月,其静刚度与动静比均满足铁标要求;在长期室外受压模拟试验中,WJ8-B弹性垫板静刚度保持率良好,60-10-17橡胶垫板与WJ7-B橡胶垫板静刚度在受压两个月后超出标准,三者动静比均满足要求。对于影响弹性垫板老化的关键性因素,需要进一步探讨验证。     

三元乙丙橡胶硫化胶力学性能及动静刚度比

研究了硫化剂用量、填充增强剂的种类及用量以及发泡倍率等对三元乙丙橡胶硫化胶力学性能及动静刚度比的影响。结果表明,动静刚度比随着橡胶交联密度的增加、填料增强作用的减弱、填料用量的减少以及发泡倍率的增大而逐渐减小。     

配方因素对天然橡胶胶料动静刚度比的影响

研究含胶率、补强体系和硫化体系对天然橡胶(NR)胶料动静刚度比的影响。结果表明:含胶率越大,胶料的动静刚度比越小;与炭黑N774胶料相比,小粒径、大比表面积炭黑N330胶料的硬度和动静刚度比较大,炭黑用量大的胶料动静刚度比较大;随着硫化时间的延长,普通硫黄硫化体系胶料的动静刚度比增大,半有效硫化体系胶料的动静刚度比基本不变。     

石墨烯取代部分炭黑对减振橡胶材料动静刚度比的影响

研究了用石墨烯取代部分炭黑后,减振橡胶材料力学性能、耐磨性能及动静刚度比的变化规律。结果表明,当炭黑与石墨烯并用质量比为15/2.5和20/2时,胶料动静刚度比较低,而且胶料具有良好的力学性能、耐磨性以及耐老化性。固定炭黑与石墨烯并用质量比为15/2.5时,研究了硫磺体系对胶料性能的影响,结果表明,当硫磺与促进剂质量比为2.5/1.5时,硫化胶具有较低的动静刚度比和高的抗动态疲劳性能,且综合物理机械性能优良。     

Novel dynamic vulcanization of polyethylene and ozonolysed natural rubber blends: Effect of curing system and blending ratio

Dynamic vulcanization was studied in terms of the change in α‐relaxation temperatures of the LDPE matrix, morphology, and mechanical properties of LDPE/ozonolysed NR blends which were vulcanized at various blend ratios and with different curing systems, i.e., peroxide and sulfur systems. The ozonolysed NR with M _w = 8.30 × 10⁵ g mol⁻¹ and M _n = 2.62 × 10⁵ g mol⁻¹, prepared by the in situ ozonolysis reaction of natural rubber latex, was used in this study. The significant change in the α‐relaxation temperature of LDPE in the LDPE/ozonolysed NR, dynamically vulcanized using the sulfur system, suggested that sulfur vulcanization of the blend gave a higher degree of crosslink density than using peroxide and corresponded with the improved damping property and homogenous phase morphology. However, the peroxide cured blends of LDPE/ozonolyzed NR gave more improvement of tensile strength and elongation at break than the sulfur cured system. Furthermore, the mechanical properties of tensile strength, elongation at break, and damping were improved by increasing the ozonolyzed natural rubber content in both DCP and sulfur cured blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Nonisothermal thermophysical evaluation of polypropylene/natural rubber based TPEs: Effect of blend ratio and dynamic vulcanization

Ozawa macrokinetic model is applied to describe the nonisothermal melt crystallization process of polypropylene (PP), in natural rubber/polypropylene (NR/PP) thermoplastic elastomers (TPEs) as a function of blend ratio and dynamic vulcanization of the rubber phase. It was found that as cooling rate increases, the crystallization temperature T_c and half time for crystallization t_1/2 get diminished. Dynamic vulcanizates show a similar trend in crystallization as that of neat PP. Crystallization rate constant and Ozawa exponent were found out for different temperatures by linear regression method using Ozawa analysis. Ozawa exponent, n_O, showed variation in values when the conversion proceeded. For neat PP, the value of n_O changes from 1.4 (102°C) to 3 (112°C). The n_O values for NR/PP 50/50 blend were higher (e.g. 4.1 at 116°C). Crystallization rate constant K_O shows a maximum at 0.5 relative crystallinity. The highest crystallization rate constants were found for NR/PP 50/50 TPEs. The activation energy for the melt crystallization was found to vary with the degree of conversion, as well as with the concentration of NR in the TPEs. Finally, attempts have been made to correlate the crystallization process with morphology of the blend. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

加成型有机硅反应过程的实时监测

用实时傅里叶变换红外光谱仪（FTIR）对乙烯基硅橡胶和含氢硅油的加成聚合过程进行了表征,得到了基团浓度消耗比反应时间变化的曲线,结果表明,在反应过程中,硅氢基与乙烯基的浓度减少呈非线性关系,这可能是硅氢基在反应过程中与空气中的物质进行了反应,从而在消耗量上较乙烯基多的缘故。     

橡胶履带压注成型整体硫化工艺研究

由于目前传统的橡胶履带制造方法都存在需分段硫化且第一模需通冷却水及第二模橡胶接头部位硫化程度不致等问题,故很容易产生橡胶裂口等质量缺陷。本文介绍了橡胶履带压注成型整体硫化工艺,该工艺将外层胶、挤出挂胶钢帘线缠绕成的环状钢帘布与传动筋板等配件一起预成型于压注式圆形活络橡胶履带内模腔内,再用注塞模将外层胶从压注室经压注孔通过平板硫化机压注到模腔内,最后硫化成产品。该工艺成型后只需硫化一次就能出成品,橡胶履带带体胶料物性均匀一致,克服了传统工艺的缺点。     

New static and dynamic stiffness testers

Instruments have been developed for the testing of stiffness of polymers in various gaseous environmental “atmospheres” over a large range of temperatures. They are based on the cantilever principle, where a small strip of a specimen is deflected statically or periodically. Changes in stiffness are measured as function of the bending force or power input, respectively. The dynamic instrument responds very sensitively to the onset of cracking in specimens due to ozone exposure. The static instrument is well suited for measuring the onset of rapidly increasing stiffness as temperatures are lowered.     

Optimization of the vulcanization process of rubber products

Selection of the optimum conditions for the vulcanization of rubber products, particularly of bulky ones, often is quite difficult. Especially in cases of high demand, it is unavoidable to destruct expensive prototypes in order to check important properties of the rubber at various locations throughout the product. Finite element calculations can be used to predict the flow of heat during the vulcanization process. By converting the total heat input at a selected location during a certain time into a so-called “effective vulcanization time” at a fixed reference temperature, it becomes possible to predict the properties of the rubber at that location. An example of such a procedure is given. However, to secure optimum conditions in this way would require repetitive (expensive) calculations. In this article a method is developed in which the vulcanization conditions are derived from the required properties of the rubber compound. The idea behind it is that optimal vulcanization is reached when at each location within the rubber product the effective vulcanization time at a selected reference temperature lies within predefined limits. The choice of the limits can be derived from the dependence of each of the properties chosen on the vulcanization time at the reference temperature.     

橡胶硫化过程的仿人智能控制

针对硫化过程中橡胶制品性能和尺寸精度控制难的问题，分析了橡胶制品硫化成型的对象特性。认为橡胶硫化过程属于明显的不确定性过程，可选择无需数学模型的仿人智能控制作为系统的控制策略。应用工控机，在Windows操作系统上开发了控制系统，试验表明该系统的可用性、鲁棒性、稳定性和控制精度令人满意。     

Morphological evolution and property changes of acrylate rubber/polyacetal thermoplastic vulcanizates during dynamic vulcanization process

A new type of thermoplastic vulcanizates (TPV) that is resistant to hot oil, high temperature, and aging was prepared using acrylate elastomer (ACM) and polyoxymethylene (POM) as raw materials. The phase transition process and micromorphology development of the blends with the change of dynamic vulcanization (DV) time, and to illustrate the effects of the phase transition and the degree of elastomer phase crosslinking on the macroscopic properties of TPV were investigated. It was shown that ACM crosslinking occurs continuously during 0–8 min of DV, whereas the phase inversion process occurs predominantly during 0–3 min. In contrast, the cross-section of the blends after phase inversion is flat, The constant elongation stress under small deformation, hardness, and permanent deformation after break are reduced, and the elongation at break, nonrelaxable modulus, and aging resistance are improved. The increase in the degree of vulcanization of the ACM phase resulted in a significant increase in the modulus of the blends under large deformation, an increase in the nonrelaxable modulus and relaxable modulus, an increase in the aging resistance, and a decrease in the elongation at tear were observed.