橡胶复合料对刹车片性能及表面开裂状态的影响

研究了两种细度的橡胶复合料不同含量时对刹车片摩擦磨损性能和表面开裂状态的影响。实验结果表明,加入一定量橡胶复合料能使刹车片摩擦面产生较少裂纹,有效改善摩擦磨损性能,当含量相同时细度较大的橡胶复合料比细度小的橡胶复合料表面更易开裂、性能更好。综合比较,当橡胶复合料细度较大、含量为20%左右时刹车片表面裂纹适宜具有较好的摩擦磨损性能。

高模量剂与橡胶粉复合改性沥青应力吸收层混合料技术性能研究

针对反射裂缝在半刚性基层沥青路面和旧路加铺改造中普遍存在的问题,为提高应力吸收层材料的抗裂性、抗车辙剂抗疲劳耐久性,阻止反射裂缝的产生和发展,将橡胶粉与高模量剂进行复配,基于车辙、低温弯曲和四分点加载疲劳试验研究了PR.S和橡胶粉掺量对应力吸收层混合料高温稳定性、低温抗裂性和抗疲劳耐久性的影响并将与STRATA应力吸收层混合料进行了对比。研究结果表明,相同PR.S掺量情况下,增大橡胶粉掺量复合改性沥青旋转黏度呈二次函数关系增大,橡胶粉和PR.S掺量对复合改性沥青软化点有显著的影响,橡胶粉对PR.S改性沥青的低温性能有明显的改善作用;以软化点≥75℃,5℃延度≥20 cm,177℃黏度≤4.5 Pa·s,25℃弹性恢复率≥65%作为判别标准优选了3种不同复配方案,经室内试验和试验路验证推荐最佳复配方案为8%PR.S+20%橡胶粉。经过试验路的应用,证明了橡胶粉和高模量剂复合改性沥青混合料作为应力吸收层式沥青路面防止反射裂缝的有效途径之一,具有更广的地区适用性。

橡胶复合改性沥青混合料路用性能分析

结合工程案例,对橡胶复合改性沥青混合料的路用性能进行验证。制定试验方案,对不同胶粉含量和SBS掺量的橡胶复合改性沥青混合料的路用性能开展试验进行验证,得出混合料各项路用性能满足设计要求。

干湿复合橡胶粉改性沥青混合料性能及抑冻破冰试验研究

以干法改性工艺将橡胶粉颗粒掺入稳定型橡胶粉改性沥青混合料中,研究了橡胶粉颗粒掺量对稳定型胶粉改性沥青混合料性能及沥青路面抑冻破冰效果的影响。结果表明:随着橡胶粉颗粒掺量增加,改性沥青混合料的路用性能与抗疲劳性能呈先提高后降低,当橡胶粉颗粒掺量为3%时,干湿复合橡胶粉改性沥青混合料具有优良的高稳定性、低温抗裂性、水稳定性和抗疲劳性能;掺入橡胶粉颗粒能够快速恢复稳定型橡胶粉改性沥青路面在凝冰条件下的抗滑性能,抑冻破冰效果随橡胶粉颗粒掺量增加而增大;综合路用性能和抑冻破冰效果,橡胶粉颗粒的最佳掺量为3%。

橡胶沥青混合料高温稳定性能提高措施研究

为研究橡胶沥青混合料的高温稳定性能,设计三种不同的方案,分析对比三种方案试件的路用性能。试验结果表明:添加高模量剂的橡胶沥青混合料、复合橡胶沥青混合料的高温性能得到改善。采用复合SBS的措施从动稳定度的结果来看,没发现其高温性能的改善。橡胶沥青混合料的低温抗裂能力比复合橡胶沥青混合料的要好,而且复合橡胶沥青混合料添加高模量剂后影响其低温抗裂性能。橡胶沥青和复合橡胶沥青由于其高黏结力使其混合料水稳定性能较好。

橡胶改性沥青混合料生产配合比调试优化及工程应用

结合橡胶复合改性沥青混合料在河南省公路项目中的应用,介绍了橡胶复合改性沥青混合料生产配合比调试过程及混合料施工温度范围,检测了试验段的主要性能指标。结果表明:热料吸水率减小可导致生产配合比空隙率减小;通过减少细集料、矿粉用量,增加粗集料用量,可增大矿料间隙率和空隙率;橡胶复合改性沥青施工各环节温度比SBS改性沥青高10℃~15℃;橡胶复合改性沥青混合料综合路用性能良好。

Thermal Oxidative Degradation and Ageing Performance of Silicone Rubber Filled with Attapulgite

The natural attapulgite(NAPT)was disaggregated by high-pressure homogenization technology combined with extrusion process to prepare the attapulgite with disaggregated rod crystal bundles(DAPT)and large specific surface area of 133.7 m^(2)/g.NAPT and DAPT were incorporated into the silicone rubber to obtain the composite NAPTSR and DAPT-SR by mechanical blending method,respectively.After thermal oxidative ageing at 300℃ for 0.5 h,temperature for the 5%weight loss increased greatly from 385℃ of the neat silicone rubber to 396-399℃ with addition of NAPT and DAPT.NAPT and DAPT enhanced the interaction between the filler nanoparticles and rubber matrix thus inhibited the nanoparticle agglomeration.The conservation rate of the side methyl group in NAPT-SR and DAPT-SR was greatly improved after ageing.Therefore,the thermal oxidative degradation and ageing performance of the silicone rubber composites was significantly reinforced.Moreover,DAPT could greatly restrain the growth of nanoparticles after ageing.Therefore,DAPT-SR showed the better retention of tensile strength(40.6%),elongation at break(34.9%)and tear strength(30.1%)compared with the corresponding mechanical properties of the neat silicone rubber(10.6%,7.4%,and 5.0%)after ageing.

Modified graphite filled natural rubber composites with good thermal conductivity

The rubber composites with good thermal conductivity contribute to heat dissipation of tires. Graphite filled natural rubber composites were developed in this study to provide good thermal conductivity. Graphite was coated with polyacrylate polymerized by monomers including methyl methacrylate, n-butyl acrylate and acrylic acid. The ratios between a filler and acrylate polymerization emulsion and those between monomers were varied. Eight types of surface modification formulas were experimentally investigated. Modification formula can affect coating results and composite properties greatly. The best coating type was achieved by a ratio of1:1 between methyl methacrylate and n-butyl acrylate. The coating of graphite was thermally stable in a running tire. Filled with modified graphite, the tire thermal conductivity reached up to 0.517–0.569 W·m-1·K-1. In addition, the mechanical performance was improved with increased crosslink density, extended scorch time and short vulcanization time.

Preparation of Novel Composite from Natural Rubber, Bagasse and Plaster

The sugar cane bagasse was treated with chemical treatment including sodium hydroxide and silane. The characterization of the modified bagasse was achieved with Fourier transform infrared spectroscopy （FTIR）, and scaning electron microscopy （SEM）. Results showed that the presence Si-CH3 group occurred on bagasse surface after chemical modification. In addition, the roughness of the modified bagasse was higher than that of unmodified bagasse due to chemical modification from sodium hydroxide. Two polymer composite types, namely （1） natural rubber NR/sugar cane bagasse and （2） NR/plaster via two-roll mill method, were prepared. The optimum cure （t90） and torque of the NR/plaster increased with increasing plaster loading in composite. In case of NR/bagasse, the tgo of this sample decreased as a function of sugar cane bagasse while torque of this sample increased with increasing sugar cane bagasse. The modulus of the resulting composite increased with increasing both plaster and sugar cane bagasse, but the tensile strength and elongation at break of the composite decreased as a function of both piaster and sugar cane bagasse in composite.

Study on properties of tetrapod-like zinc oxide whisker/silicone rubber foam composites

In this paper, the microcellular silicone rubber foams, strengthened with tetrapod-like Zinc Oxide whisker（T-ZnOw） are prepared. Through further characterization, it can be seen that the average cell diameter size of the filled with T-ZnOw is reduced. The distribution uniformity of microcellulars is improved obviously with increasing T-ZnOw filler. The reason that introduction of T-ZnOw can greatly enhance mechanical properties of the microcellular silicone rubber foams is its good interfacial adhesion with the matrix contributes. It is also found that the reducing effects of T-ZnOw on the compressive stress relaxation ratio of microcellular silicone rubber foams, and the improvement is obvious with increasing T-ZnOw filler.

Measurement of large deformation of nylon cord-rubber composite and effects of perpendicular loads on its stress-strain behaviors

Effects of transverse loads on longitudinal stress strain behaviors and longitudinal constant tensile loads on transverse stress strain behaviors of single ply of nylon cord rubber composite are studied respectively under biaxial tensile condition with cruciform specimen. Effects of transverse constant tensile load on longitudinal tensile mechanical properties are indistinctive compared with corresponding uniaxial longitudinal tensile mechanical properties. It can be relative to larger difference between longitudinal and transverse mechanical properties. Its dominating failure mode is typical fiber dominated mode; However, Experiment results indicate that transverse mechanical properties of nylon cord rubber composite with longitudinal constant tensile loads are distinct from its uniaxial transverse tensile mechanical properties. It can be attribute to action of longitudinal tension that makes material rigidify in the direction perpendicular to fiber, Mode of failure is representative of matrix dominated failure. For the measurement of large deformation up to 50 percent, a special CCD imaging method is employed in the experimental investigation that makes measurement of large deformations more precise.

Improving the Abrasion Resistance of ＂Green＂ Tyre Compounds

Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.

Effect of modified aramid nanofiber on compatibilization of natural rubber/epoxidized natural rubber composites

The combination of natural rubber(NR)with epoxidized natural rubber(ENR)could improve the wet slid resistance,mechanical properties,abrasion resistance and thermo-oxidative aging resistance of NR,which showed important research significance.Aramid nanofiber,as a new nano filler for polymer developed in recent years,had the advantages of both macroscopic fibers and polymer nanomaterials.The NR/ENR composites were prepared by dry mixing with NR and the pre-composite prepared from ENR latex and the modified aramid nanofibers(t-ANF).

Good dispersion of hydrophilic nanoscale silica in rubber matrix and the effects on rubber nanocomposites

Using the industrial technologies of rubber latex irradiation,preparation of nanoscale silica(SiO2) slurry,mixing irradiated rubber latex with SiO2 slurry,and the spray drying,we have prepared the ultrafine fully-vulcanized powder carboxyl styrene-butadiene rubber(UFPCSBR)/SiO2 nanocompound powder,in which the SiO2 particles and UFPCSBR particles are isolated and stuck each other.When the UFPCSBR/SiO2 nanocompound powder is mixed with crude rubber,the UFPCSBR particles are dispersed well in rubber matrix because of their good compatibility,then the SiO2 particles are also dispersed well in rubber matrix because of the carrier nature of the UFPCSBR particles during the mixing procedure,and the novel rubber/UFPCSBR/SiO2 nanocomposites are fabricated.Compared with the rubber composites prepared by mixing the crude rubber with the UFPCSBR powder and SiO2 powder one after the other,the novel UFPCSBR/SiO2 nanocompound modified rubber/UFPCSBR/SiO2 nanocomposites have better abrasion resistance,higher tensile strength and tear strength,and lower heat build-up data.Noteworthily,the tanδ-temperature curve of the novel rubber/UFPCSBR/SiO2 nanocomposites has the second tanδ peak due to the newly generated boundary layer surrounding the SiO2 particles,increasing the tanδ values in the temperature range of 0-20℃,which is very important to the research of green tyre tread.