丁苯橡胶与甲基丙烯酸缩水甘油醋功能化反应的研究

本文考察了丁苯橡胶在引发剂存在下，用甲基丙烯酸缩水甘油脂（ＧＭＡ）功能化反应时，反应时间、引发剂用量、ＧＭＡ浓度对功能化的影响，通过计算碳—碳双键，酯基与环氧基的相对吸光度推测了反应机理。     

Influence of rubber composition on change of crosslink density of rubber vulcanizates with EV cure system by thermal aging

Variation of the crosslink density of a rubber vulcanizate depending on the rubber composition after the thermal aging was studied with single rubber, biblend, and triblend vulcanizates of natural rubber (NR), butadiene rubber (BR), and styrene‐butadiene rubber (SBR). The efficient vulcanization (EV) system was employed to minimize the influence of free sulfur in the vulcanizate on the change of the crosslink density. Thermal aging was performed at 40, 60, and 80°C for 20 days with 5‐day intervals. The crosslink densities of the vulcanizates after the thermal aging increase. For the single rubber vulcanizates, variation of the crosslink density by the thermal aging has the order: SBR > BR > NR. For the biblend vulcanizates, variations of the crosslink densities of the NR/SBR and SBR/BR blends are larger than that of NR/BR blend. Variation of the crosslink density of the vulcanizate increases by increasing the SBR content in the vulcanizate. Variation of the crosslink density of the rubber vulcanizate depending on the rubber composition was explained by miscibility of the blends, combination reaction of the pendent groups, and mobility of the pendent group. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1378–1384, 2000     

交联密度对HNBR/聚甲基丙烯酸正丁酯IPN阻尼性能的影响

用序列法制备氢化丁腈橡胶(HNBR)/聚甲基丙烯酸正丁酯(PnBMA)互穿聚合物网络(IPN)材料,通过改变两网络的硫化剂用量得到不同交联密度的HNBR/PnBMA IPN。采用动态粘弹谱仪测试IPN的阻尼性能,结果表明HNBR/PnBMA IPN材料的阻尼特性与交联密度密切相关。随着第一网络交联密度的增加,阻尼曲线逐渐由双峰转变为单峰,阻尼峰宽降低。第二网络交联密度的增加使阻尼曲线整体下降,双峰形态不变。通过改变两网络的交联密度可调整阻尼峰的位置、宽度及阻尼峰值。     

HDPE／LDPE混合物熔融接枝GMA的研究

采用熔融接枝的方法,制备了(HDPE/LDPE)-g-GMA（甲基丙烯酸缩水甘油酯）接枝吻,研究了引发剂的用量、GMA的用量、苯乙烯（St)/GMA的配化、转速、反应时间等因素对接枝率的影响。确立了最佳的接枝配方和工艺条件：过氧化二异丙苯（CDP）用量0.1份、GMA用量3份、St用量3份、温度180℃、转速60r/min、反应时间为10min。接枝反应动力学曲线与接枝反应过程的机理特征相吻合。红外光谱的分析结果表明GMA确实接到了大分子链上;DTA分析结果表明,接枝物中GMA的引入导致大分子链的规整性降低,熔融温度略有下降。     

甲基丙烯酸缩水甘油酯的合成

甲基丙烯酸甲酯和甲醇反应得到甲基丙烯酸钾,和环氧氯丙烷（ECH）反应,合成了甲基丙烯酸缩水甘油酯。考察了催化剂选择、反应温度、反应时间、物料配比、催化剂用量等因素对反应的影响。结果表明,较佳的反应条件为：十六烷基三甲基溴化铵为催化剂,反应温度1100C,反应时间4h,n（甲基丙烯酸钾）：n（ECH）：1：7,催化剂用量0．2g。在此条件下,产品收率可达79％,含量大于98％。     

纳米氧化锌对天然胶乳膜干燥及硫化性能影响研究

采用失重法和溶胀法研究了普通氧化锌和纳米氧化锌活化的天然胶乳膜的干燥动力学,以及干燥过程中胶乳膜交联密度变化.结果表明:天然胶乳厚胶膜在成膜后仍含有大量水分并且去除困难.纳米氧化锌活化胶膜的干燥速率明显高于普通氧化锌胶膜.干燥温度对干燥过程影响显著,干燥时间随干燥温度升高明显降低.随着干燥的进行,2种氧化锌活化的胶乳膜的交联密度均迅速上升,在相同条件下,纳米氧化锌活化胶乳膜交联密度均比普通氧化锌的大.纳米氧化锌对天然胶乳膜的干燥及硫化过程均有促进作用.     

两种方法凝固天然橡胶的动态性能对比

分别采用自然凝固和酸凝固方法制备天然橡胶(NR),并比较2种方法凝固NR的交联密度、硫化特性、动态性能和生热等的差异。试验结果表明,自然凝固NR的交联密度和弹性模量较高,硫化速度快,动态损耗小,生热低。     

混炼工艺对Si-69改性白炭黑填充HPR850/CB24的影响

研究了混炼工艺对Si-69改性白炭黑填充HPR850/CB24的影响,混炼工艺区别如下,是否具有150℃的保温平台,白炭黑是否一次投料。实验结果表明,150℃的保温平台和白炭黑一次投料的混炼工艺能够改善白炭黑的分散,抑制白炭黑的填料网络,并且能促进白炭黑、Si69、橡胶分子链彼此间的硅烷化反应,交联密度也得到了显著的提高。同时保证了硫化胶具有较好的磨耗性能、力学性能。     

交联密度对丁腈橡胶阻尼性能的影响

测定了丁腈橡胶硫化胶的交联密度和阻尼性能，考察交联密度对阻尼性能的影响。结果表明，交联密度是阻尼性能的重要影响因素。交联密度的增加可以提高丁腈橡胶的损耗峰所对应的温度并使储能模量E＇的转变区域向高温方向移动，但交联密度过高会导致有效损耗温度区域缩小。     

Swelling and mechanical properties of crosslinked hydrogels containing N-vinylpyrrolidone

Copolymers of 2-hydroxyethyl methacrylate/N-vinyl-2-pyrrolidone (HEMA/NVP) and methyl methacrylate (MMA)/NVP were prepared in the presence of varying amounts of ethylene glycol dimethacrylate (EGDMA) and methylene diacrylamide (MDA) as crosslinkers by photopolymerisation. The resultant solid polymers were swollen to equilibrium in water at 293 K to produce hydrogels. These hydrogels were characterised by soluble fraction and equilibrium water content. The gels were also characterised by compression—strain measurements, which enabled the calculation of Young's modulus and effective crosslink density. The differences in these properties of HEMA/NVP and MMA/NVP polymer series and the effects of MDA versus EGDMA as a crosslinker were explained in terms of compositional drift of polymerisation, heterogeneous crosslinking and hydrophilicity/hydrophobicity of the components involved. In comparison with EGDMA, MDA was found to be more effective in reducing the soluble fraction of the polymers studied and to produce less rigid networks when swollen.     

Influence of internal strain on change of crosslink density of natural rubber vulcanizates by thermal ageing

Change of crosslink density of natural rubber (NR) vulcanizates by thermal ageing at 60 °C has been studied under swollen conditions in solvents to investigate the influence of internal strain applied to the vulcanizate on the crosslink density change. The internal strain was controlled by swelling with various solvents such as n‐hexane, toluene, tetrahydrofuran (THF), methanol and water. The order of degree of the swelling is toluene ≈ THF > n‐hexane > methanol > water. The influence of curing system has been investigated with the vulcanizates cured by the conventional and EV cure systems. After thermal ageing, the apparent crosslink densities of the swollen vulcanizates in n‐hexane, toluene and THF decrease irrespective of the cure systems, while that of the swollen vulcanizate in water increases. For the swollen vulcanizates in methanol, the apparent crosslink density of the vulcanizate with the conventional cure system after thermal ageing increases while that of the vulcanizate with the EV cure system decreases. The decrement of the apparent crosslink density of the vulcanizate after thermal ageing becomes larger and larger upon increasing the internal strain. © 2001 Society of Chemical Industry     

Morphology,thermal behavior,and mechanical properties of PA1010/PP and PA 1010/PP-g-GMA blends

The modification of polypropylene (PP) was accomplished by melt grafting glycidyl methacrylate (GMA) on its molecular chains. The resulting PP-g-GMA was used to prepare binary blends of polyamide 1010 (PA1010) and PP-g-GMA. Different blend morphologies were observed by scanning electron microscopy (SEM) according to the nature and content of PA1010 used. Comparing the PA1010/PP-g-GMA and PA1010/PP binary blends, the size of the domains of PP-g-GMA were much smaller than that of PP at the same compositions. It was found that mechanical properties of PA1010/PP-g-GMA blends were obviously better than that of PA1010/PP blends, and the mechanical properties were significantly influenced by wetting conditions for uncompatibilized and compatibilized blends. A different dependence of the flexural modulus on water was found for PA1010/PP and PA1010/PP-g-GMA. These behaviors could be attributed to the chemical interactions between the two components and good dispersion in PA1010/PP-g-GMA blends. Thermal and rheological analyses were performed to confirm the possible chemical reactions taking place during the blending process. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1489–1498, 1997     

Styrene‐assisted melt free radical grafting of glycidyl methacrylate onto an ethylene and propylene rubber

This article deals with the efficiency of using styrene (St) as a comonomer to promote the melt free radical grafting of glycidyl methacrylate (GMA) onto an ethylene and propylene rubber (EPR) in a batch mixer and a corotating self‐wiping twin screw extruder. The addition of St to an EPR/GMA/peroxide system increases not only GMA's grafting yield but also its grafting rate. The time required for the EPR/GMA/peroxide system without St to reach a given amount of grafted GMA is at least 10 times that needed for the same system in the presence of an equimolar amount of St. For example, about 60 min are required for the EPR/GMA/dicumyl peroxide (composition: 100/3.0/0.3 by weight) to reach 1.5 phr (parts per hundred resin) GMA (i.e., 1.5 g grafted GMA per 100 g EPR). The same amount of grafted GMA is reached in < 3 min when 3.0 phr St is charged to the system. This significant reduction of reaction time is crucial for a successful free radical grafting of GMA on EPR in a corotating twin screw extruder, because the residence time in such a machine is typically on the order of 0.5–5 min. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 125–133, 1999     

白炭黑/天然橡胶复合材料疲劳过程中微观结构与性能演变

本研究采用单轴疲劳机对白炭黑/天然橡胶复合材料样品进行了不同程度的疲劳,并对样品在不同阶段的微观结构和力学性能进行了表征。透射电镜扫描显示在疲劳过程中白炭黑的分散程度以及填料网络出现了先变好后变差的现象。溶胀法测试交联密度显示交联密度也经历了一个先降低后升高再降低的过程,说明复合材料的填料网络和交联网络在疲劳的过程中经历了一个破坏重建再破坏的过程。动态热机械分析仪(DMA)显示在疲劳过程中样品的玻璃化转变温度是先降低后升高。模量-应变曲线显示10万次疲劳后的试样内部填料的分散非常均匀,Payne效应减弱。力学性能测试表明经历了5-10万次的疲劳后,样品的力学性能超过了未疲劳样品。     

酚醛树脂/古马隆树脂对再生橡胶性能的影响

研究了204酚醛树脂(204树脂)和古马隆树脂在再生橡胶中的应用。测定了2种树脂对再生橡胶的交联密度、硫化特性、门尼粘度、力学性能、动态力学性能的影响。结果表明,2种树脂均可以有效地降低再生橡胶的门尼粘度;204树脂的固化作用可以提高硫化胶的整体交联密度,有利于再生橡胶力学性能的提高,当其用量为3phr时达到最佳效果;古马隆树脂有利于再生橡胶断裂伸长率的提高,当其用量为4.5phr时达到最佳效果。