NR传统硫化体系的抗硫化返原特性

介绍了NR抗硫化返原的主要措施和机理,并在NR传统硫化体系的基础上,比较了4种典型的抗硫化返原助剂（芳香酸锌皂Structol AKT73, 二烷基多硫化磷酸酯SDT／G,Duralink HTS和Perkalink900)的用量和在不同硫化温度下硫化对NR胶料硫化和抗返原理性能的影响,在相同用量情况下,Perkalink900的抗硫化返原能力最强。     

抗硫化返原剂在天然橡胶中的应用研究

研究抗硫化返原剂WY808,WK901,WY9188,HT-K在全天然橡胶体系配方中的应用,对比其抗硫化返原效果。结果表明:在4种抗硫化返原剂中,抗硫化返原剂WY9188和WK901的抗硫化返原效果具有明显优势;抗硫化返原剂WY9188在硫化返原后期和整体阶段的抗硫化返原效果较好;抗硫化返原剂WK901在硫化返原前期的抗硫化返原效果优良;4种抗硫化返原剂均能改善过硫化状态硫化胶的物理性能;在0. 5～1. 5份用量范围内,抗硫化返原剂WK901的最佳用量为1. 5份,抗硫化返原剂WY808的最佳用量为1份。抗硫化返原剂WK901,WY808,HT-K可以直接添加,不需要对原硫化体系进行调整。使用抗硫化返原剂WY9188时需要适当减小促进剂用量。     

天然橡胶硫黄促进体系的抗返原硫化动力学的模拟

提出了天然橡胶硫黄促进剂体系的抗返原硫化动力学模型,建立了抗返原硫化过程中总交联密度,多硫键,单／双硫键及碳－碳键的动力学方程。     

NR硫化返原动力学及主要抗硫化返原助剂

对硫化返原的动力学、抗硫化返原助剂的作用机理、不同抗硫化返原助剂在不同的配合体系中的用量及对硫化胶性能的影响进行评述。对于抗硫化返原助剂,在半有效硫化体系中Ｓｉ６９抗返原性最好。在传统硫化体系中ＨＶＡ－２最好。实际应用时不同本的配方应采取相应的抗硫化还原剂。     

NR硫化返原的研究 Ⅱ.半有效硫化体系

研究了半有效硫化体系硫化ＮＲ的返原反应,对双－（γ－三乙氧基硅烷基丙基）－四硫化物（Ｓｉ６９）抗返原作用的原因进行了分析,通过测定硫化曲线,物理性能和溶胀指数,考察常见的３种工业化抗返助剂（Ｓｉ６９,Ｎ,Ｎ′－间亚苯基双马来酰亚胺（ＨＶＡ－２）和环己烷二硫代硫酸盐二水合物（ＨＴＳ）对ＮＲ硫化返原反应的抑制效果,实验结果表明,抗返原助剂可改善了ＮＲ的热氧化性能Ｓｉ６９的抗返原效果最好,用量以３份为宜     

用硫化返原率曲线表征胶料的抗硫化返原性能

提出用硫化返原率曲线表征胶料的抗硫化返原性能的观点。硫化返原率曲线可以清晰地反映胶料的硫化返原过程和准确表征其抗硫化返原性能，可以作为抗硫化返原剂或胶料的特征曲线；不同抗硫化返原剂的作用机理决定了它们的抗硫化返原效果及其应用场合。     

天然橡胶硫黄促进剂体系的抗返原硫化动力学的模拟

提出了天然橡胶硫黄促进剂体系的抗返原硫化动力学模型,建立了抗返原硫化过程中总交联密度、多硫键、单／双硫键及碳－碳键的动力学方程。     

抗硫化返原剂的合成与应用

参考二元促进剂体系的设计,合成抗硫化返原剂O,O-二丁基二硫代磷酸二硫化物(TBuPD)、1,6-双(二丁基二硫代磷酸)己烷(DBPH)、1,6-双(二苄基二硫代氨基甲酰)己烷(DBTH),探究其对天然橡胶的硫化性能、交联结构和力学性能的影响。结果表明,DBTH、TBuPD和DBPH的加入使混炼胶在150℃下硫化60 min后的硫化返原率从8.2%降低到3.8%以下;硫化胶在长时间的硫化后均有良好的力学性能保持率;硫化胶在长时间的硫化后滚动阻力降低。     

NR硫化返原的研究 Ⅱ半有效硫化体系

研究了半有效硫化体系硫化ＮＲ的返原反应,对双（γ三乙氧基硅烷基丙基）四硫化物（Ｓｉ６９）抗返原作用的原因进行了分析。通过测定硫化曲线、物理性能和溶胀指数,考察常见的３种工业化抗返原助剂［Ｓｉ６９,Ｎ,Ｎ′间亚苯基双马来酰亚胺（ＨＶＡ２）和环己烷二硫代硫酸盐二水合物（ＨＴＳ）］对ＮＲ硫化返原反应的抑制效果。实验结果表明,抗返原助剂可改善ＮＲ的热氧化性能;Ｓｉ６９的抗返原效果最好,用量以３份为宜,ＨＶＡ２次之,ＨＴＳ最差。     

NR硫化返原的研究 Ⅰ普通硫黄硫化体系

研究了ＮＲ的返原反应。通过测定硫化曲线、物理性能和溶胀指数考察了常见的几种工业化抗返原剂（ＤＨＴＳ,ＨＶＡ２和Ｓｉ６９）对ＮＲ硫化返原反应的抑制效果。实验结果表明,以ＨＶＡ２的抗返原效果最好,ＤＨＴＳ次之,Ｓｉ６９最差,同时ＨＶＡ２和ＤＨＴＳ还能改善ＮＲ的热氧老化性能。对硫化曲线进行解析发现硫黄硫化反应服从一级反应规律。     

An effect of OMMT on the anti‐reversion in NR/CR blend system

The influence of dispersed organomodified montmorillonite (OMMT) on curing behaviors of natural rubber (NR)/chloroprene rubber (CR) blend was investigated. The preparing procedure includes premixed rubber individually with its additives and then the two components were blended according to gum weight ratio for NR to CR is 75/25. Sulfur was chosen as the vulcanizing agent, and the research on vulcanization was carried through the rotor‐Rheometer at 143°C. Transmission electron microscopy showed the dispersion of OMMT in the rubber blends and detected little OMMT migrated into the NR phase. The scorch time (t₁₀), optimum vulcanizing time (t₉₀), and reversion phenomenon were both measured by the curing curve; meanwhile, the crosslinking densities and mechanical properties were determined through equilibrium swelling‐method, magnetic resonance crosslink density spectrometer, and tensile tests. By comparing the test results, an interesting phenomenon was discovered and furthermore was verified that the addition of OMMT can obviously modify the reversion resistance of the binary blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

淀粉/天然橡胶复合材料的结构与热稳定性研究

将淀粉进行糊化改性,将改性淀粉在乳液状态下与天然胶乳共混,制备淀粉/天然橡胶复合材料。利用扫描电镜(SEM)和热重分析(TG)表征复合材料的结构,并测定了其力学性能。研究结果表明:淀粉经糊化后,淀粉粒子在天然橡胶中分散均匀,粒径明显减小,复合材料的热稳定性和力学性能明显提高。     

TPI/NR力学性能的分子动力学模拟

为研究杜仲胶(TPI)和天然橡胶(NR)之间的相容性、TPI/NR共混物的力学性能,采用分子动力学(MD)法在Compass力场条件下对其进行了模拟。研究结果表明:通过比较溶度参数差值(Δδ)的大小可预测TPI与NR之间的相容性,TPI/NR属于相容体系;与纯TPI相比,TPI/NR共混物的静态力学性能及动态拉伸抗疲劳性能更加优越。     

天然橡胶/反式-1,4-聚异戊二烯并用胶硫化体系的研究

考察了3种典型促进剂，噻唑类(M)、次磺酰胺类(NOBS)和秋兰姆类(TMTD)，普通硫化体系(CV)、半有效硫化体系(SEV)、有效硫化体系(EV)及促进剂NOBS用量、硫黄用量对并用胶性能的影响。结果表明，NOBS是并用胶作为胎面胶较为理想的促进剂，CV体系和SEV体系可以获得较好的综合性能。反式-1，4-聚异戊二烯(TPI)并用胶的性能变化规律与一般橡胶有所不同，当硫黄用量为3～5份，促进剂NOBS用量0．8～1．0份时，并用胶可获得良好的综合性能。     

NR/LLDPE热塑性弹性体泡沫材料的制备与性能研究

采用化学交联模压法制备天然橡胶/线性低密度聚乙烯（NR/LLDPE）共混型热塑性弹性体泡沫材料。研究了橡塑比、发泡剂用量、硫磺用量以及模压发泡成型压力对泡沫材料的力学性能和相对密度的影响,并对泡沫材料的微观结构进行了荧光显微镜分析。结果表明：橡塑比、发泡剂用量、硫磺用量和压力对材料的性能影响较大,且当橡塑共混比为70/30、发泡剂用量为10 phr、硫磺用量为1.5phr和压力为1 MPa时,可制得密度较低且具有较好综合力学性能的泡沫材料;微观结构表征显示,此条件下制得的泡沫材料的泡孔较小、大小均一、分布均匀且以闭孔为主。     

Effect of Cyclic Deformations on the Dynamic‐Mechanical Properties of Silica‐Filled Butyl Rubber

The effect of the chemical modification of the silica surface by the silane coupling agent (Si69) on both the real and the imaginary parts of the shear compliance (J′, J″) on silica‐filled butyl rubber vulcanizates was investigated in a wide temperature and frequency range, ?70 to 120 °C and 10^?4 to 10 Hz, respectively. In addition, the stress‐strain measurements, DSC, and TEM were carried out. Moreover the effect of stress‐strain cyclic deformation up to ten times with maximum deformation 80% of the elongation at break on J′, J″ is also studied. It was found that the filler network recovers after cyclic stress‐strain in a time scale of one year at room temperature.

Transmission electron photographs of the butyl rubber [IIR] vulcanizates: (a) IIR, unfilled, (b) IIR, filled with 20 phr SiO₂, (c) IIR,filled with 20 phr SiO₂ + 1.6 phr Si69.     

Influence of filler-polymer interactions on the cure mismatch of dissimilar polymeric blends

Cure mismatch between the blends of two dissimilar polymers, poly[ethylene (vinyl acetate)] (EVAc-28, VAc content 28%) and polychloroprene (CR) was investigated through rheometric, mechanical, and dynamic mechanical properties. These studies indicate cure-heterogeneity due to fast curing as well as degradation of CR with dicumyl peroxide (DCP) at 170°C, which facilitates easy liberation of acidic HCl. The low temperature curing of unfilled blends at 145°C reduces the rate of curing as well as liberation of HCl, leading to lower cure heterogeneity and improved physical properties compared to those cured at 170°C. The high specific component of surface energy of carbon black (N110) leads to better filler-polymer interaction with more polar CR and causes lowering in effective occluded volume measured from storage modulus. Carbon black suppresses the cure heterogeneity of the blends and improves their physical properties considerably. CR, which shows higher minimum rheometric torque compared to EVAc-28, is more viscous and hence carbon black incorporation is relatively difficult. This also leads to higher agglomerate structure causing higher networking factor. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 321–328, 1997     

RPA分析天然橡胶不同硫化体系的动态性能

用RPA分析不同硫化体系对NR动态性能的影响进行研究。研究发现：频率增加,混炼胶和硫化胶的G’增加,混炼胶的Tanδ减小,硫化胶的Tanδ增加;应变增加,混炼胶和硫化胶的G’减小,混炼胶的Tanδ在应变大于20%迅速增加,硫化胶的Tanδ在应变2%出现峰值;温度增加,混炼胶的G’减小、Tanδ增加,硫化胶的G’增加、Tanδ减小。不同硫化体系三种扫描下,硫化胶的G’顺序：SEV>EC>CV>EV,主要是单硫键、双硫键与多硫键保持一定的比例才能获得较高的G’。     

Effect of Silane Coupling Agent on the Mechanical Properties of Clay Filled Styrene Butadiene Rubber

Abstract

The effect of treatment of coupling agent [Bis (3-triethoxy-silyl-propyl) tetrasulphide] on mechanical properties of composites made from styrene butadiene rubber and clay is reported in this paper. The coupling agent in the form of solution (1.0%) was used for treatment of the filler. The treatment resulted in enhancement of mechanical properties of composites when compared with composites containing untreated clay. The properties under consideration were tensile strength, modulus at 100% and 400%, Young's modulus, hardness, etc. Good reinforcement was observed due to treatment of 1% coupling agent. Tensile strength was improved by 11%, modulus at 400% was found to improve by 237%, elongation at break was improved by 250%, while Young's modulus also was improved by 298% for treated clay composites, respectively, at 0.41 volume fraction when compared with untreated clay composites.     

The Effect of Accelerator/Sulphur Ratio on the Cure Time and Torque Maximum of Epoxidized Natural Rubber

Abstract

The cure time of accelerated sulphur vulcanization of Epoxidized Natural Rubber (ENR 25) was studied while one grade of unmodified natural rubber– Standard Malaysian Rubber Light (SMR L) was used as a control. Five accelerators, viz. 2-mercaptoben-zothiazole (MBT), tetramethylthiuram disulphide (TMTD), zinc dimethyldithiocarbamate (ZDMC), N-tert-butyl-2-benzothiazylsulphenamide (TBBS) and diphenylguanidine (DPG) were used in the study and the vulcanization systems used were conventional vulcanization (CV), semi-efficient vulcanization (semi-EV) and efficient vulcanization (EV). Monsanto Moving-Die Rheometer (MDR 2000) was used to determined the cure time in the temperature range of 100-180°C. The results indicate that cure time decreases exponentially with increasing temperature for the two rubbers studied. At a fixed curing temperature, ENR 25 shows shorter cure time compared to that of SMR L. This has been attributed to the activation of the double bond by the adjacent epoxide group in ENR 25. Studies of the effect of varying amounts of M Bata a fixed sulphur concentration show that cure time decreases as the accelerator concentration increases. ENR 25 shows higher torque maximum than SMR L. This observation can be related to the oxirane group which is bulky and thus accounts for increased glass; transition temperature with increase in the level of epoxidation. Of the vulcanization systems, CV shows the highest torque maximum followed by semi-EV and than EV. This trend can be attributed to the amount of active sulphurating agent which increases with increasing accelerator concentration. It was also found that the influence of accelerator/sulphur ratio becomes less significant as vulcanization temperature increases.