橡塑密封技术发展现状与趋势

阐述了近年来我国橡塑密封行业的发展情况及在各行业的应用,综述了橡塑密封结构设计、橡塑密封材料、检验检测和制造工艺的发展现状,分析了国内橡塑密封行业和技术与国外发达国家先进密封技术发展存在的差距和不足,提出了橡塑密封技术的发展方向,并就未来我国橡塑密封行业的发展提出了建议。     

影响硅橡胶涂层疏水性的因素

目的寻找影响硅橡胶涂层疏水性的因素,并找到相应的提升改进方法。方法以液体硅橡胶为基体,通过燃烧橡胶条熏附、添加纳米SiO2粉末混合和喷洒纳米SiO2粉末附着这三种不同方式,来制备超疏水表面涂层。通过改变纳米粉末的加入方式、加入质量,研究疏水性的最佳条件。并通过光学显微镜测量静态接触角评价表面疏水性能,寻找影响其疏水性的因素。结果最佳的方法为熏烧的烟尘附于液体硅橡胶涂层表面,大多数试验样本出现超疏水特性,静态接触角最高可达159°,平均值150°,静态接触角提高40°以上;次之为均匀喷洒纳米SiO2粉末,部分试验样本出现超疏水特性,静态接触角最高为145°,平均值135.5°,静态接触角提高30°~40°;简单搅拌混合的提升效果最差,没有试验样本出现超疏水特性,静态接触角最高可达124°,平均值108.5°,静态接触角只提高5°~15°。结论构建超疏水涂层的关键在于能否成功构建出微纳米的二级微观结构,简单的物理混合、搅拌会使纳米粉末被覆盖掉,无法表现出其特性。涂层的疏水能力与接触周围的实际微观长度有关。     

拉锻式摩擦塞焊的热力耦合解析模型和试验验证

为快速得到拉锻式摩擦塞焊的焊接工艺参数，对焊接过程进行预测，建立了摩擦塞焊过程的扭矩、轴向力、功率和能量等指标的力学模型和热力耦合解析模型。模型的输入量为焊接塞棒的几何参数、材料属性、焊接转速和进给速度，输出量为焊接过程的扭矩、轴向力、功率和能量等。在自主设计的拉锻式摩擦塞焊设备上进行了焊接试验。通过将试验数据的输入和输出指标与理论模型值进行对比分析，验证了理论解析模型的可行性。     

Properties of tire tread compounds based on functionalized styrene butadiene rubber and functionalized natural rubber

Tire tread compounds based on various rubber types, that is, solution styrene-butadiene rubber (SSBR), functionalized (propylamine and dimethoxysilane) solution styrene-butadiene rubber (F-SSBR), natural rubber (NR), chloroacetate-modified natural rubber (CNR), and their blends, were prepared and used as raw rubbers. Properties of tire tread compounds and tire performance were then investigated. Due to the presence of chloroacetate group on its mainchains, CNR demonstrates increases in glass transition temperature and rubber-filler interaction compared to NR leading to a significant improvement in tire performance, particularly wet grip (WG; ~88%), fuel-saving efficiency (FSE; ~15%), and abrasion resistance (~11%). Similarly, F-SSBR shows a greater tire performance than SSBR (~20, ~13, and ~7% improvements in WG, FSE, and abrasion resistance, respectively). Among the rubber blends, F-SSBR/CNR gives the highest tire performance, followed by F-SSBR/NR, SSBR/CNR, and SSBR/NR, respectively. The results suggest the significant enhancement in properties of tire tread compounds by the presence of active functional groups in NR and SSBR molecules. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48696.     

Natural rubber-graft-poly(2-hydroxyethyl acrylate) on cure characteristics and mechanical properties of silica-filled natural rubber composites

The grafting of poly(2-hydroxyethyl acrylate) onto natural rubber (NR-g-PHEA) was used to compatibilize NR composites with silica filler. The NR/silica compounds were prepared with various grafting percentages of NR-g-PHEA (0, 6.5, 10.5, and 14.5%) and fixed amounts of 3 parts per hundred of rubber (phr) NR-g-PHEA and 20 phr silica. The cure characteristics were examined using a moving die rheometer. The physicomechanical properties of NR/silica composites were determined in terms of tensile strength, bound rubber content, and dynamic mechanical analysis. Thermal properties were assessed with thermogravimetric analysis. The results showed that scorch time and cure time tend to decrease with the level of grafting in NR-g-PHEA. The NR-g-PHEA decreased tan δ, whereas bound rubber content in NR/silica compounds increased, which indicates improved silica dispersion in the NR matrix. The mechanical properties improved with level of grafting in NR-g-PHEA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48738.     

Vinyl-functionalized polyborosiloxane for improving mechanical and flame-retardancy performances of silicone rubber foam composites

In this work, we first synthesized vinyl-terminated polyborosiloxane (pBS) filler, and then incorporated it into silicone rubber foam (SRF) matrix to prepare composite materials through a simple chemical dehydrogenative foaming method under ambient conditions. The pBS filler with reactive groups could form physical and chemical crosslinking networks in SRF, leading to an excellent dispersion level of pBS in the SRF matrix. Moreover, the inserted pBS could remarkably improve the mechanical and flame-retardancy properties of SRF-pBS composites. Intriguingly, the SRF-pBS6 foam containing 6 wt% of pBS possessed a uniform porous structure and balanced mechanical properties (σ_b = 65.4 kPa, ε_b = 56.7%, compression stress 97.1 kPa), thermal conductivity (0.102 W (m K)^?1), limiting oxygen index (29.8%) and UL-94 rating (V-0) among the prepared foams. In addition, the incorporated pBS (6 wt%) could synergistically catalyze the formation of a silicon–boron strengthened ceramic-like protective layer under fire and was capable of suppressing heat and smoke production in the SRF-pBS6 foam. The present work provides a promising way for developing high mechanical and flame-retardant polymeric foam materials with good thermal insulation. © 2021 Society of Industrial Chemistry.     

Influence of the weight ratio of polydimethylsiloxane modified gelatin to silicone rubber on the potential performance of asymmetric bilayer membranes as wound dressings

Asymmetric bilayer membranes have been regarded as ideal wound dressings for skin regeneration. Our previous work reported the potential advantages of polydimethylsiloxane modified gelatin/silicone rubber (PGE/SR) asymmetric bilayer membrane as a wound dressing. However, it is still unknown whether the proportion of the two components of the bilayer membrane has a prominent influence on its relevant performance. Herein, various PGE/SR membranes with different PGE:SR weight ratios (100:25, 100:50 and 100:100) were fabricated through a self‐stratification method driven by surface tension gradients. Subsequently, the effects of the PGE:SR ratios on the relevant performance (i.e. porous structure, mechanical properties, degradability and biocompatibility) of PGE/SR membranes were systematically investigated. The current results demonstrate that the separating force between the PGE and SR components was reduced significantly on increasing the content of SR, and in particular the PGE/SR1 membrane (100:25) exhibited a well‐defined asymmetric bilayer structure with high porosity, appropriate toughness, water uptake, swelling ratio and water permeability. Concomitantly, the maximum weight loss for the PGE/SR1 membrane was ca 70.65% after 9 days of enzymatic degradation, which met the typical healing period of a normal skin wound. In addition, both the original and degraded PGE/SR1 membrane possessed favorable cytocompatibility in vitro, suggesting its potential application as a wound dressing. © 2019 Society of Chemical Industry     

Preparation of epoxidized acrylonitrile butadiene rubber and its compatibilization effect on water-swellable rubber composites

In this research, water-swellable rubbers (WSRs) were prepared by the blending of acrylonitrile butadiene rubber (NBR) with epoxidized acrylonitrile butadiene rubber (ENBR), precipitated silica, vulcanizing agents, and polyacrylic acid sodium (PAAS) as superabsorbent polymers (SAPs). ENBR was prepared with a molybdenum trioxide catalyst and a tert-butyl hydroperoxide oxidant through a free-radical reaction under specific conditions and was used as a compatibilizer to improve the interfacial adhesion of the NBR matrix and hydrophilic components of the WSRs. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to analyze the structure and properties of ENBR. The dispersion of silica and SAPs in the rubber matrix was investigated by transmission electron microscopy. The presence of ENBR enhanced the water-absorption properties of the WSRs. The NBR–ENBR composites exhibited a higher mechanical performance after water absorption than that without ENBR. Both the swelling ratio and the absorption rate increased with the ENBR content. When the weight ratio of NBR–ENBR was 25/75, an equilibrium swelling ratio of 172% (13% higher than that of the sample without ENBR) was obtained. Scanning electron microscopy analysis revealed that the addition of ENBR improved the compatibility between the SAPs and the NBR matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47694.