共查询到20条相似文献，搜索用时 15 毫秒
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Matthew R. Bont;Stephen Johnston; 《Polymer Engineering and Science》2024,64(7):3147-3159
Injection molded liquid silicone rubber (LSR) devices are used in high performance applications for the medical, transportation, and energy industries. Anisotropic shrinkage in LSR injection molding has been observed in practice but is generally not well understood. This research focused on anisotropic shrinkage based on flow and cross-flow orientation. LSR parts were molded at varying thicknesses, shear rates, fill times, and cure temperatures. Simulations accurately predicted the fill pattern and were used to predict the cure rate of the samples. LSR molding showed a significant range of linear shrinkage ratios between the flow versus crossflow directions shrinkage from above 1.30 to below 0.92. The underlying driver of anisotropic behavior is believed to be reaching a sufficient average cure through the cross section combined with flow-induced orientation. Shrinkage anisotropy was found to generally increase with increasing shear rate in regions where curing was significant. Additionally, dynamic mechanical analysis showed a connection between the polymer network using the modulus and anisotropic linear shrinkage. 相似文献
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文中综述了加成型液体硅橡胶的注射成型工艺,介绍了液体注射成型工艺、共注射成型工艺和气体辅助注射成型工艺及冷流道技术在液体硅橡胶中的应用。 相似文献
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The processing of liquid silicone rubber (LSR) in the injection molding process to molded parts offers high economic potential due to its great scalability. Unlike the well-researched and understood injection molding process of thermoplastics, LSR still lacks basic process knowledge. The cavity pressure curve shows a completely different pattern, as the cold LSR expands strongly once placed in the hot mold due to volume dilation. During processing of LSR exothermic and irreversible cross-linking, occurs. In this work, a method is introduced to display the cross-linking reaction in the cavity pressure curve. Using a self-developed testing device and conventional differential scanning calorimetry measurements, a correlation between cross-linking and the pressure signal can be demonstrated. A typical deflection is evaluated in the pressure curve by differentiating, which is attributed to the cross-linking. The relationships established are confirmed by pressure measurements in the mold during the processing of LSR in the injection molding process. The knowledge gained contributes to a better understanding of the process, helps to optimize existing processes and save resources. Existing cavity-pressure-measuring-systems are to be supplemented by an evaluation logic and thus, in addition to cycle time optimization, process variations are to be detected, energy consumption optimized and quality ensured and verified. 相似文献
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The processing of hard and liquid silicone rubbers (LSR) are compared by means of modeling and simulation. The curing process for both, hard and liquid silicone, are modeled using the auto‐catalytic Kamal‐Sourour model and a nonlinear regression method is used to find the kinetic parameters. The fitted kinetic model is then combined with the heat balance equations to simulate real processing conditions. Both resins are compared in terms of process performance and consistency of the final part. The results show that even though hard silicone rubbers are less expensive resins, its processing conditions present several issues of consistency and quality control when compared with LSR. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119:1864–1871, 2011 相似文献
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聚氨酯反应注射成型固化过程数值模拟 总被引：2，自引：0，他引：2
依据反应动力学和能量守恒方程的基本理论，对聚氨酯反应注射成型的固化过程进行了合理的假设和必要的简化，建立了体系反应程度和温度的数学模型。采用显示有限差分法并结合数学软件Matlab对固化过程进行了动态模拟.结果表明：固化初始的20s内交联反应剧烈。体系迅速升至最高温度，交联度达到80％所需时间与经验值一致．约为17s。同时为优化反应注射成型工艺因素，探讨了催化剂浓度、原料初始温度和模具温度等对体系的影响。结果表明：催化剂浓度增加，使体系固化周期缩短，制品内部交联度的变化减小，但延长了制品处于高温部分的时间；模具温度主要影响制品壁面附近的反应，而物料初始温度则能影响到体系的最高温度，尤其是在低模温情况下更加明显. 相似文献
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介绍了硅橡胶模具胶的生产工艺及反应釜、高速混合机、行星搅拌机、捏合机等几种用于硅橡胶模具胶生产的设备。经比较发现采用湿法工艺对白炭黑进行表面处理时，捏合机是较适合的设备。 相似文献
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加成注压型硅橡胶的研制 总被引：1，自引：0，他引：1
以二氢硅氧烷和硅氢油为交联剂(SiH/SiVi=1.1—1.2),含过氧基铂络合物为催化剂(用量10ppm),用先后经二甲基二氯硅烷和六甲基二硅氮烷处理的二氧化硅为填料(用量40份),研制了加成注压型硅橡胶。所用生胶由多种不同分子量的聚有机硅氧烷组成,其分散指数大于10,GPC峰值分子量为15万—20万。混炼胶可在180℃下于5min内注压硫化成型,其拉伸强度为8.3MPa,伸长率为800％,撕裂强度为44kN/m,基本达到国外同类产品水平。 相似文献
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综述近年来在非轮胎橡胶制品领域拓展应用的一些具有特殊性能和特种用途、能在苛刻条件下使用的高性能特种弹性体。本综述第3部分报道近年来高性能硅橡胶领域的一些研究和应用进展。添加新型热稳定剂（气相法二氧化钛）和耐热增效剂（3价金属-有机硅络合物）可以显著提高硅橡胶的耐高温性能。低苯基硅橡胶是比目前通用的甲基乙烯基硅橡胶耐高低温性能更优异的硅橡胶,可在－70～250 ℃热空气环境中长期使用,也可在300 ℃下短期使用。采用集中交联技术可获得高撕裂强度甲基乙烯基硅橡胶。概述陶瓷化硅橡胶的组成和陶瓷化过程,简述国内在瓷化体系（成瓷填料和助溶剂）以及阻燃陶瓷化硅橡胶方面的研究状况。介绍加成型液体硅橡胶的基本组成、功能性添加剂和交联反应原理及其在输配电用复合绝缘子中的应用。 相似文献
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综述近年来在非轮胎橡胶制品领域拓展应用的一些具有特殊性能和特种用途、能在苛刻条件下使用的高性能特种弹性体。本综述第3部分报道近年来高性能硅橡胶领域的一些研究和应用进展。添加新型热稳定剂（气相法二氧化钛）和耐热增效剂（3价金属-有机硅络合物）可以显著提高硅橡胶的耐高温性能。低苯基硅橡胶是比目前通用的甲基乙烯基硅橡胶耐高低温性能更优异的硅橡胶,可在－70～250 ℃热空气环境中长期使用,也可在300 ℃下短期使用。采用集中交联技术可获得高撕裂强度甲基乙烯基硅橡胶。概述陶瓷化硅橡胶的组成和陶瓷化过程,简述国内在瓷化体系（成瓷填料和助溶剂）以及阻燃陶瓷化硅橡胶方面的研究状况。介绍加成型液体硅橡胶的基本组成、功能性添加剂和交联反应原理及其在输配电用复合绝缘子中的应用。 相似文献