Reinforcement of Styrene-Butadiene Rubber with Silica Modified by Silane Coupling Agents: Experimental and Theoretical Chemistry Study

The properties of styrene-butadiene rubber (SBR) reinforced by modified silica was investigated according to national standards. Silica was modified by silane coupling agents KH-570, KH-590, and KH-792. The optimized geome-tries of molecular modified silica reinforced SBR were obtained by using B3LYP calculation of density functional theory with the 6-31+G basis sets. The natural bond orbital analyses were carried out. The Si—O bond length of silica modified by KH-792 was the shortest and the electronegative of O was the highest. It indicated that the connection between silica and KH-792 was the tightest. Higher tensile strength and elongation of reinforced SBR was obtained by silica modified with the KH-792. It was caused by large delocalization of lone pair electrons of the two N atoms in KH-792. The S—C bond length in silica modified by KH-590 was longer than the ordinary S—C bond length. Then the sulfur free radical (·S·) was produced more easily in vulcanization. The degree of crosslink was increased by the cross-linkage of the rubber molecule and the sulfur free radical. That was why the highest stress and tear strength of reinforced SBR was produced when silane coupling agent KH-590 was used. The calculation results was in accord with experimental data.

Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites

The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/thermoplastic polyurethane(TPU) composites.The treated kenaf fiber,NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine.The polymer composites were then fabricated using the hot press to form a sample board.The sample was cut and prepared and water absorption,density,thickness swelling and DMA tests were performed.As far as physical properties are concerned,composites with the highest NR amount of shows the best results,which indicates good fiber bonding adhesion.The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature.

Pyrolysis of vulcanized styrene-butadiene rubber via ReaxFF molecular dynamics simulation

Styrene-butadiene rubber(SBR)is widely used in tires in the automotive segment and vulcanization using sulfur is a common process to enhance its mechanical properties.However,the addition of sulfur as the cross-linking agent usually results in impurities in pyrolysis products during rubber recycling,and thus the desulfurization during tire pyrolysis attracts much attention.In this work,the pyrolysis of vulcanized SBR is studied in detail with the help of Reax FF molecular dynamics simulation.A series of crosslinked SBR models were built with different sulfur contents and densities.The following Reax FF MD simulations were performed to show products distributions at different pyrolysis conditions.The simulation results show that sulfur products distribution is mainly controlled by sulfur contents and temperatures.The reaction mechanism is proposed based on the analysis of sulfur products conversion pathway,where most sulfur atoms are bonded with hydrocarbon radicals and the rest transfer to H_(2)S.High sulfur contents tend to the formation of elemental sulfur intermediate,and temperature increase facilitates the release of H_(2)S.

MORPHOLOGY,INTERFACIAL INTERACTION AND PROPERTIES OF STYRENE-BUTADIENE RUBBER/MODIFIED HALLOYSITE NANOTUBE NANOCOMPOSITES

A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier.The structure,morphology and mechanical properties of SBR/m-HNT nanocomposites,especially the interfacial interactions,were investigated.SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at ...

Strengthening and toughening styrene-butadiene rubber by mechanically interlocked cross-links

Styrene-butadiene rubber(SBR)is an indispensable material in modern society,and the necessity for enhanced mechanical properties in SBR persists,particularly to withstand the rigors of challenging environmental conditions.To surmount the limitations of conventional cross-linking modes,mechanical bonds stabilized by host-guest recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks(MINs).Compared with covalently cross-linked network,the representative MIN exhibits superior mechanical performance in terms of elongation(1392%)and breaking strength(4.6 MPa),whose toughness has surged by 17 times.Dissociation of host-guest recognition and subsequent sliding motion provide an effective energy dissipation mechanism,and the release of hidden length is also beneficial to enhance toughness.Furthermore,the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties,which can return to initial state with one minute rest interval.We aspire that this direct introduction method can serve as a blueprint,offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials.

Improving Thermal-oxidative Aging Resistance of Styrene-butadiene Rubber by Antioxidant Loaded Silica Aerogel

The antioxidant N-isopropyl-N'-phenyl-p-phenylenediamine(4010NA)was dissolved in ethanol and impregnated into silica aerogel(SAG)via vacuum-pressure cycles,yielding composite particles(A-N)with enhanced sustained-release and reinforcing capabilities.The effect of A-N on the mechanical properties and thermal-oxidative aging resistance of styrene-butadiene rubber(SBR)vulcanizates was investigated.TGA and BET assessments indicated that the loading efficiency of 4010NA in SAG reached 14.26%within ethanol's solu bility limit.Incorporating A-N into SBR vulcanizates significantly elevated tensile strength by 17.5%and elongation at break by 41.9%over those with fumed silica and free4010NA.Furthermore,A-N notably enhanced the thermal-oxidative aging resistance of SBR.After aging for 96 h at 100℃,the tensile strength and elongation at break of SBR with A-N sustained 70.09%and 58.61%of their initial values,respectively,with the retention rate of elongation at break being 62.8%higher than that of SBR with fumed silica and free antioxidant.The study revealed that A-N composite particles significantly inhibited the crosslinking in SBR's molecular chains,reducing hardening and embrittlement during later thermal-oxidative aging stages.

Magnetic,thermal stability and dynamic mechanical properties of beta isotactic polypropylene/natural rubber blends reinforced by NiZn ferrite nanoparticles

The dispersion of magnetic nanoparticles in matrix is crucial to ensure optimum performance of the composite.The difficulty level of achieving good dispersion is further increase when a multi-phases of matrix is present.A pre-coating technique of magnetic nanoparticles with polypropylene using ball-mill prior to melt-blending process was employed to prepare a multi-phases thermoplastic natural rubber composite.The effect of filler loading(2 wt%-10 wt%) on morphology,structure,magnetic properties,thermal stability and dynamic mechanical properties of the composites were investigated.It was found that the NiZn ferrite nanoparticles act as nucleating agent to form beta isostatic polypropylene thermoplastic composites.The composites’ magnetic properties are directly dependent on the filler concentration.The dispersion of magnetic fillers in polymer matrix plays role in affecting the magnetic properties and thermal stability.The preference of filler to locate at amorphous phase has distorted the chain orientation of natural rubber and polypropylene.Hence,the polymorphism and crystallinity of the matrix varied as the filler loading increased,affecting the dynamic mechanical properties.It was found that 8 wt% NiZn nanocomposite exhibits highest E’ and tanδ,indicating the dynamic mechanical properties of NiZn nanocomposite are affected by β-phase degree.

Study the Effect of Recycled Tire Rubber on the Mechanical and Rheological Properties of TPV (HDPE/Recycled Tire Rubber)

Thermoplastic elastomeric blends prepared from blending of (10%, 20%, 30%, 40% and 50 wt%) high density polyethylene(HDPE) and (10%, 20%, 30%, 40% and 50 wt%) ground rubber tire (TPV-R). The blends prepared contain (HDPE)/polybutadiene (TPV-V). The two blends were successfully prepared through a dynamic vulcanization process, involving dicumyl peroxide (3%) as vulcanizing agent. The data of the mechanical (tensile strength at yield, %elongation and young modulus) and rheological properties (shear stress, shear rate, viscosity, flow behavior index and activation energy of melt flow) of the TPV-V and TPV-R showed that there was comparable results between the two blends.

3种汽车密封条用TPV的性能研究

研究了3种国产汽车密封条用热塑性硫化橡胶(TPV)产品(TPV-1,TPV-2,TPV-3)的力学性能、耐热性能、微观形貌和热氧老化性能。结果表明:3个产品的树脂相可能均为嵌段共聚聚丙烯(PP)。3个产品中,TPV-3的拉伸强度、断裂伸长率和撕裂强度均最大,TPV-1的拉伸强度和断裂伸长率均最小,TPV-1和TPV-2的撕裂强度相当,TPV-1的耐热性能和热氧老化性能均最好,TPV-3的耐热性能最差,TPV-2和TPV-3的热氧老化性能相当,在温度70℃、时间22 h、压缩率25%下,TPV-1的压缩永久变形最大,TPV-3最小,在温度23℃、时间72 h、压缩率25%下,TPV-1和TPV-3的压缩永久变形相当,TPV-2的压缩永久变形最小。

不同填料补强的IIR/PP型TPV材料性能对比

以炭黑、白炭黑和轻质碳酸钙为补强填料,通过动态硫化法制备了不同填料补强的丁基橡胶/聚丙烯(IIR/PP)型热塑性硫化胶(TPV)材料。研究表明,不同填料与基体材料的相容性均良好,不同填料补强的TPV材料耐热性能相差不大。轻质碳酸钙填料补强的TPV具有相对较高的硬度和拉伸强度,更低的压缩永久变形值,但其热氧老化性能相对较差。炭黑和白炭黑填料补强的TPV材料热氧老化性能保持得相对更好。

环保丁基再生橡胶/聚氯乙烯热塑性弹性体阻尼材料的制备与性能研究

采用共混法制备环保丁基再生橡胶/聚氯乙烯(PVC)热塑性弹性体阻尼材料(以下简称热塑性弹性体),研究环保丁基再生橡胶用量、PVC改性剂种类和用量、填料(磁粉和硅藻土等)用量对热塑性弹性体性能的影响。结果表明:随着环保丁基再生橡胶用量的增大,热塑性弹性体的力学性能和压缩永久变形下降,密度增大,阻燃性能无明显变化;当环保丁基再生橡胶用量为40份时,热塑性弹性体的综合性能良好且性价比高。采用20份氯化聚乙烯与10份苯乙烯-乙烯-丙烯-苯乙烯共聚物并用作为PVC改性剂,热塑性弹性体的综合性能较优。随着填料用量的增大,热塑性弹性体的密度、阻燃性能和磁性提高,但力学性能下降;当填料用量为120份时,热塑性弹性体的综合性能较优,阻尼温域为-55~100℃,损耗因子≥0.3,阻尼性能好。

Insights into the Payne Effect of Carbon Black Filled Styrene-butadiene Rubber Compounds

As a widely used reinforcing filler of rubber, carbon black(CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical behaviors for styrene-butadiene rubber(SBR)/CB compounds and CB gel(CBG) during large deformation/recovery to investigate the contribution of conductive CB network evolution to the Payne effect of the compounds. In the highly filled compounds, the frequency dependence of their strain softening behavior is much more remarkable than that of their CB network breakdown during loading, while during unloading the unrecoverable filler network hardly affects the complete recovery of modulus, both revealing that their Payne effect should be dominated by the disentanglement of SBR matrix. Furthermore,the bound rubber adjacent to CB particles can accelerate the reconstruction of continuous CB network and improve the reversibility of Payne effect. This may provide new insights into the effect of filler network, bound rubber, and free rubber on the Payne effect of CB filled SBR compounds.

橡塑比对EPDM/PA6热塑性动态硫化橡胶的性能影响研究

采用动态硫化法挤出成型制备共混型三元乙丙橡胶(EPDM)/尼龙6(PA6)热塑性动态硫化橡胶(TPV),对不同比例的EPDM/PA6共混物进行了研究。结果表明:脆断微观形貌分析,四组橡塑比均形成了“海岛”结构,其中橡塑比为70/30的橡胶微粒尺寸和分散状态更均匀。加工流变性分析,橡塑比为70/30的扭矩有最小值;随橡塑比的增大,拉伸强度和断裂伸长率先上升后下降,分别在EPDM/PA6为60/40和70/30时达到最大值。从降低成本考虑,选用橡塑比为70/30的为宜。

New Fabrication and Mechanical Properties of Styrene-Butadiene Rubber/Carbon Nanotubes Nanocomposite

A novel technology to prepare styrene-butadiene rubber （SBR）/carbon nanotubes （CNTs） composites was developed by combining a spray drying method and a subsequent mechanical mixing process. The cross-linking degrees of the vulcanized composites increased gradually with the additive CNTs contents. By comparing with those of the pure SBR composites, the mechanical properties such as tensile strength, tear strength and hardness of the composites filled with CNTs at certain contents were dramatically improved almost by 600%, 250% and 70%, respectively. The fabrication of the CNTs filled with SBR composites by combination of the spray drying method and subsequent mechanical mixing process was effective for enhancing the reinforcement effects of CNTs in rubbers. The novel technology can also open a new route for the modification and reinforcement on the nanocomposites with large amount of CNTs.

影响TPV阻燃电缆料耐油性能的研究

以三元乙丙橡胶(EPDM)/聚乙烯(PE)/聚丙烯(PP)三元热塑性动态硫化橡胶(TPV)为基材,制备出耐油、阻燃EPDM/PE/PP三元TPV复合材料。研究了不同材料对热塑性弹性体(TPV)耐油性能的影响。结果表明:高密度聚乙烯(HDPE)的添加可以增强TPV的耐油性,且随用量增加,其效果更显著;氢化苯乙烯-丁二烯嵌段共聚物(SEBS)和石蜡油的添加会削弱TPV的耐油性;具有高等规度的聚丙烯(PP)也可提升TPV的耐油性能。这些结果对于研发用于电线电缆的阻燃耐油TPV的配方设计具有积极意义。

EVA/CR TPV的压缩应力松弛及其可逆回复行为

采用动态硫化法制备了基于乙烯-醋酸乙烯酯共聚物(EVA)/氯丁橡胶(CR)的热塑性硫化胶(TPV),并对其力学行为、微观结构、压缩应力松弛、可逆回复行为以及EVA/CR质量比对可逆回复不同阶段应力松弛行为的影响进行了研究。结果表明:EVA/CR TPV的压缩应力松弛行为主要受EVA相影响,CR分散相对压缩应力松弛行为的影响较小;提高热处理温度或延长热处理时间,均可显著提高TPV压缩应力松弛可逆回复程度,且当温度在EVA熔点附近时,TPV应力松弛的可逆回复程度接近100%。

废旧轮胎胶粉/聚合物复合材料的研究进展

废旧轮胎胶粉(GTR)的资源化利用有利于“碳达峰、碳中和”发展战略的实施。系统综述了GTR在橡胶、热塑性树脂、聚氨酯、环氧树脂、聚酮树脂等聚合物改性领域的研究现状;从GTR复杂的化学组成、微观形态和聚集态结构等角度出发,提出GTR/聚氨酯复合材料的研发有望成为废旧轮胎胶粉高值化再利用的重要研究方向。

公路用聚合物改性沥青研究现状及发展趋势

现代化公路交通所呈现的货车轴载增大、车流量大幅增加以及渠化行驶普遍等特点要求公路沥青路面应具备更好的高温抗车辙、低温抗开裂以及耐磨损等路用性能。为探索聚合物改性沥青的改进方向,通过分析聚合物改性沥青的研究现状,明确了聚合物与沥青相容性影响因素涉及沥青质分子的数量与大小、聚合物分子的数量和大小、软沥青质的芳香性等方面。改善聚合物与沥青相容性的方法包括反应性单体移植、对聚合物进行官能化、使用活性聚合物等技术。聚合物与沥青混合时需要一定程度的溶解度和溶胀性才能获得改善黏弹性的聚合物网络,且聚合物溶解度不宜过高。深入分析了弹性体、塑性体、橡胶等聚合物的改性效果,热塑性弹性体、塑性体、胶粉等聚合物的应用为改性沥青提供了帮助,但是常用的几种聚合物在应用过程中均表现出一定的局限性,热塑性弹性体改性沥青,尤其是SBS和SEBS,因其优异性能而具有应用潜力,但需进一步研究以解决相容性和稳定性问题。塑性体改性剂,如WPE,通过形成网状结构提高沥青刚度,但储存稳定性有待改善。橡胶改性沥青利用废旧轮胎,既环保又经济,但其在高温下的稳定性和环境影响需进一步研究。该领域未来研究方向,包括聚合物复配、微观机理分析和改性剂与沥青的相容性提升等方面。整体而言,聚合物改性沥青的研究和应用前景广阔,但仍需解决部分技术难题以实现更广泛的工程应用。

增容剂对有机硅/聚氨酯热塑性弹性体性能的影响

本文研究了增容剂种类和用量对有机硅/聚氨酯热塑性弹性体物理性能及微观形貌的影响。研究发现:不同增容剂均可以有效改善硅橡胶/聚氨酯热塑性弹性体的拉伸强度、断裂伸长率和硅橡胶微球尺寸,但效果具有显著差别。其中,马来酸酐接枝苯乙烯/乙烯/丁二烯/苯乙烯嵌段共聚物对弹性体性能的改善效果最优异,拉伸强度和断裂伸长率增幅分别为41.6%和22.6%,马来酸酐接枝聚烯烃弹性体次之,马来酸酐接枝聚丙烯和乙烯丙烯酸共聚物相近,但也比未添加增容剂的胶料拉伸强度提高24.3%,断裂伸长率略有提高。增容剂的用量对硅橡胶和聚氨酯的界面相互作用和物理性能具有明显影响,其随着增容剂用量的增加呈先增加后不变的现象。

GC法测定不同基质的骨通贴膏中挥发性成分的含量

目的:建立一种准确和高灵敏度的气相色谱方法检测骨通贴膏中挥发性成分,并比较不同基质中骨通贴膏挥发性成分的含量。方法采用气相色谱法,色谱柱为Agilent HP-5(30 mm,0.32 mm,0.25μm),检测器为FID,进样口温度为200℃,检测器温度为240℃,采用程序升温。结果:樟脑在0.023~5.84 mg/mL、薄荷脑在0.009~2.20 mg/mL及桂皮醛在0.004~1.04 mg/mL内线性关系良好,相关系数均大于0.999。两种基质的骨通贴膏中樟脑的平均回收率在96.8%~104.8%、薄荷脑的平均回收率在98.3%~109.0%、桂皮醛的平均回收率在90.5%~98.4%。热塑性橡胶基质的骨通贴膏中樟脑和薄荷脑含量均明显高于传统橡胶基质的骨通贴膏的含量。结论该方法准确性好、灵敏度高、重复性好,可作为骨通贴膏产品中挥发性成分测定的方法。热塑性橡胶基质制备工艺比传统橡胶基质制备工艺更适合于挥发性成分。