复合促进剂对高剪切应力诱导轮胎胶脱硫反应的影响

采用在轮胎胶粉与三元乙丙橡胶(EPDM)熔融挤出过程中添加脱硫反应促进剂的方法,研究了过氧化物、多硫化物及其复合促进剂对脱硫共混物凝胶含量、门尼黏度以及硫化产物共混丁苯橡胶再硫化材料力学性能的影响。结果表明,过氧化物或多硫化物均可促进脱硫反应;当以过氧化物/多硫化物或过氧化物/多硫化物/水为复合促进剂时,可产生协同效应,促进脱硫反应和保护产物双键。在210℃和1000 r/min的脱硫反应条件下,以2,5-二甲基-2,5-双(叔丁基过氧)乙烷(DBPH)/450/水为复合促进剂时,三者的协同作用可使脱硫共混物的凝胶含量和门尼黏度分别达到39.2%和7.2,脱硫共混物共混丁苯橡胶再硫化材料的拉伸强度和断裂伸长率分别达到19.4 MPa和609.0%。     

轮胎胶应力诱导脱硫及对聚丙烯的增韧作用

在轮胎胶粉的熔融挤出过程中添加线型高分子材料作为溶胀剂和承载流体,并通过提高双螺杆挤出机转速的高剪切应力诱导方法,研究了螺杆转速和挤出反应温度对轮胎胶脱硫共混物凝胶含量、熔体流动速率、溶胶特性黏数及红外光谱(FT-IR)的影响。结果表明,双螺杆挤出机的高剪切应力可诱发轮胎胶颗粒中交联网络的断链反应和氧化降解作用,引起脱硫共混物凝胶含量的明显下降、熔体流动速率的明显增加、溶胶特性黏数的明显减小及溶胶分子链中碳碳双键和醚键基团明显增加。在最佳脱硫反应条件下,所得脱硫共混物可使聚丙烯(PP)(J430)材料的缺口冲击强度由10.5kJ/m2提高至47.7kJ/m2。     

亚临界流体与高剪切应力对EPDM废胶粉脱硫反应的影响

在废旧三元乙丙橡胶粉(WEPDM)与未硫化三元乙丙橡胶(EPDM)混合物的熔融挤出过程中,采用改变亚临界流体品种和提高双螺杆挤出机螺杆转速的方法,研究了亚临界流体品种与高剪切应力对脱硫共混物DEPDM/EPDM的凝胶含量、门尼黏度、溶胶红外光谱及脱硫共混物共混三元乙丙橡胶与原EPDM共混再硫化材料EPDM/(DEPDM/EPDM)力学性能的影响,对再硫化材料的试样断面形貌也进行了扫描电镜观察。结果表明,亚临界流体水或醇的存在均能促进脱硫、解交联反应的进行,特别是在以亚临界乙醇水(7∶3)混合物作为反应介质的条件下,脱硫反应中交联S-S键断裂选择性明显增大,所得产物凝胶含量降低,门尼黏度增大,其再硫化材料力学性能也明显增加。挤出机的螺杆转速和脱硫反应温度均存在最佳值(220℃,600~800 r/min)。在以醇水混合物为反应介质的最佳条件下(220℃,600~800 r/min),其脱硫共混物共混EPDM再硫化材料EPDM/(DEPDM/EPDM)的拉伸强度和断裂生长率分别达到26.7 MPa和606.3%。     

轮胎胶应力诱导脱硫及热塑性弹性体的制备

采用提高双螺杆挤出机螺杆转速的高剪切应力诱导方法,研究了螺杆转速、挤出反应温度及螺杆长径比对脱硫轮胎胶共混物凝胶含量、熔体流动速率和溶胶红外吸收光谱的影响。研究了脱硫工艺条件对脱硫轮胎胶/HDPE/EPDM热塑性弹性体力学性能的影响。实验结果表明,挤出机的高剪切应力作用,可诱发轮胎胶粒中交联网络的断链和氧化降解作用,引起脱硫共混物凝胶含量的下降、熔体流动速率的增加和脱硫共混物溶胶分子链中醚键、酯键、过氧酸和磺酸酯基团的明显增加。挤出机螺杆转速越快、挤出反应温度越高或螺杆长径比越大,其所得热塑性弹性体中未脱硫凝胶颗粒尺寸就越小。     

废橡胶胶粉/HDPE/POE热塑性弹性体的动态硫化

以过氧化二异丙苯(DCP)为硫化剂,研究了废橡胶胶粉／高密度聚乙烯(HDPE)／乙烯-辛烯共聚物(POE)(50/25/25)热塑性弹性体的动态硫化．考察了过氧化二异丙苯(DCP)用量对该共混物力学性能的影响．结果表明,加入DCP后,废橡胶胶粉／HDPE／POE共混物的交联度增加。动态硫化提高了共混物的力学性能,DCP用量为0．5份时．共混物具有最大的拉伸强度(8．01MPa)和断裂伸长率(225％)．扫描电镜观察结果表明,动态硫化后共混物的界面结合更加紧密．有利于力学性能的提高。废橡胶胶粉／HDPE／POE热塑性弹性体具有良好的耐老化性和再加工性．可以循环使用。     

动态硫化聚氯乙烯／橡胶共混型热塑性弹性体的研究

本文选用硫磺、二硫化四甲基秋兰姆和2,4,6-三巯基-1,3,5-三嗪三种硫化体系及聚氯乙烯与丁腈橡胶和丁苯橡胶的共混物,用动态硫化法制备了一类性能优异的材料——聚氯乙烯/橡胶共混型热塑性弹性体,具有强度高、永久变形小、可重复加工等特点。考查了共混比、交联荆含量和品种、聚氯乙烯树脂品种、以及相容性等因素对此材料力学性能的影响。实验结果表明:交联剂品种和用量对力学性能有重要影响;聚氟乙烯与橡胶分子之间的相互作用力越大,则此共混型热塑性弹性体的力学性能越好。     

废旧轮胎橡胶的常温应力诱导固相力化学脱硫化研究

利用固相力化学反应器实现对废旧轮胎橡胶的常温力化学脱硫化。实验结果,表明胶粉的交联密度和凝胶含量随碾磨次数增加显著降低,通过碾磨,再硫化橡胶的力学性能得到显著提高。碾磨40次后,拉伸强度由碾磨前2.3 M Pa提高到10.9 M Pa;断裂伸长率由碾磨前的69.6%提高到290.0%。再硫化胶的断面形貌分析表明,用脱硫胶制得的胶片具有良好的界面结合。     

PVC／NBR共混型热塑性弹性体的形态结构

用扫描电子显微镜、动态力学谱仪和测定凝胶含量等方法,研究了动态硫化的聚氯乙烯/丁腈橡胶40(PVC/NBR-40)共混型热塑性弹性体的形态结构,并探讨了结构与性能的关系。结果表明:共混物的性能决定于动态共硫化时形成的凝胶含量和凝胶组成。为了达到良好的综合性能,凝胶含量应大于60％。PVC/NBR-40是单相的共混体系,动态共交联增加了PVC与NBR分子链之间的相互作用,并且使两种聚合物混合的均匀程度增加。本文提出了此材料的结构模型,指出动态硫化PVC/NBR-40共混型热塑性弹性体是一种新型的热塑性半互穿网络聚合物材料。     

有机锌盐橡胶硫化促进剂作用机理研究进展

介绍了2-巯基苯并噻唑锌、烷基二硫代氨基甲酸锌、黄原酸锌和烷基二硫代磷酸锌时天然橡胶硫化的作用机理.促进剂的催化活性主要源自促进剂与硫磺等形成高硫化活性的交联先驱体.硫化过程中,多硫交联键形成后,至少存在交联、脱硫和降解3种竞争反应,这些竞争反应的程度与促进剂种类和用量有关.促进剂的催化活性不仅影响交联键的形成而且影响交联键的脱硫和降解.促进剂活性越大,硫化速度越快,但交联键脱硫和降解也越快,硫化返原越快.     

动态硫化NR／HDPE热塑性弹性体的研究

本文采用母胶子混动态硫化新工艺，以硫黄为硫化体系，制备了ＮＲ／ＨＤＰＥ共混热塑性弹性体。考察了橡塑比，共混温度，共混时间，硫化剂、促进剂用量、增塑剂及填料的用量对共混物性能的影响。实验结果表明，当橡塑比为６０：４０，硫化剂和促进剂用量分别为１．８和１份时，综合性能良好，采用增容剂技术，可使共混热塑性弹性体的物理机械性能达到最佳。     

Blends of ultrasonically devulcanized tire-curing bladder and butyl rubber

The devulcanization of the butyl rubber based tire-curing bladder was carried out with a grooved barrel ultrasonic extruder. The devulcanized rubber was blended at different ratios with the carbon black filled virgin butyl rubber and cured. The rheological and mechanical properties, as well as gel fraction and crosslink density of the revulcanized rubber and vulcanizates of blends have been measured. The blend of ground tire-curing bladder and carbon black filled butyl rubber has also been prepared for comparison purpose. Compared to the blend containing the ground rubber, compounding of the blends containing the devulcanized bladder were easier and their vulcanizates had smoother surface. In addition, the vulcanizates containing devulcanized tire-curing bladder and virgin rubber showed substantially improved mechanical properties than the vulcanizate of the devulcanized rubber alone.     

废橡胶超声波再生的研究

废旧橡胶的再生,是关系到环保和资源综合利用的重要课题,超声波再生法,被认为是最具发展前途的再生方法之一,本文对废旧轮胎胶粉的超声波脱硫过程进行了实验研究。结果表明,超声波能有效地对硫化胶进行脱硫再生,超声波的振幅和作用间隙对脱硫过程起关键作用。     

废旧橡胶热-机械剪切脱硫过程及机理

利用元素分析仪、红外光谱仪研究了废旧橡胶热-机械剪切脱硫过程及其机理。在未加任何脱硫剂的情况下,利用双螺杆挤出机提供的热能和强剪切作用对硫化橡胶进行了脱硫回收,研究发现,硫化橡胶的交联密度下降到71%,恢复了再加工性能,并且微观结构也发生了显著的变化。提出了交联硫键断裂后以活性硫侧挂基形式存在的理论,解释了再生胶脱硫后不需外加硫磺仍可以硫化的现象。溶胶的红外光谱给这一理论提供了有力的证明。根据脱硫反应前后官能团的变化推测出脱硫反应可能的机理。     

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.     

Modelling the compression behavior of ground tire rubber

The purpose of this paper was to study elastomer powder from crushed used tires (CUTs). In particular, the behavior of the green density of elastomeric powder was analyzed by varying compaction pressure. In the Anglo‐saxon bibliography, this powder is known as ground tire rubber: ground tire rubber (GTR). The density of the tyre was made using a hydrostatic balance, the analysis of grain size using cribbing sieves, and the measures of compression parameters by means of a Universal Testing Machine. The main goal was to obtain a behavior model of ground tire rubber along different compaction pressures. This model was used to predict optimum compaction pressures in order to achieve the highest density. This was the first step to obtain recycled products when sintering processes are applied, evidently if thermal compression was used as a manufacturing process. This established model predicted the evolution of green density versus compaction pressures very accurately.     

EVM/EPDM共混物的阻尼性能

选用双叔丁基过氧化异丙基苯(BIPB)作为硫化剂,采用动态力学性能(DMA)测试对乙烯-醋酸乙烯酯橡胶(EVM)和三元乙丙橡胶(EPDM)共混物的阻尼性能进行了研究.结果表明,不同配比的EVM700和EPDM4640共混时,出现有"谷底"的双阻尼因子峰,不能有效拓宽阻尼温域;丙烯酸锌可以使共混物的阻尼因子峰增高和拓宽;...     

Effects of adsorptive properties of biofilter packing materials on toluene removal

Various adsorptive materials, including granular activated carbon (GAC) and ground tire rubber (GTR), were mixed with compost in biofilters used for treating gaseous toluene, and the effects of the mixtures on the stability of biofilter performance were investigated. A transient loading test demonstrated that a sudden increase in inlet toluene loading was effectively attenuated in the compost/GAC biofilter, which was the most significant advantage of adding adsorptive materials to the biofilter packing media. Under steady conditions with inlet toluene loading rates of 18.8 and 37.5 g/m³/h, both the compost and the compost/GAC biofilters achieved overall toluene removal efficiencies greater than 99%. In the compost/GAC mixture, however, biodegradation activity declined as the GAC mass fraction increased. Because of the low water-holding capacity of GTR, the compost/ground tire mixture did not show a significant improvement in toluene removal efficiency throughout the entire operational period. Furthermore, nitrogen limitations affected system performance in all the biofilters, but an external nitrogen supply resulted in the recovery of the toluene removal efficiency only in the compost biofilter during the test periods. Consequently, the introduction of excessive adsorptive materials was unfavorable for long-term performance, suggesting that the mass ratio of the adsorptive materials in such mixtures should be carefully selected to achieve high and steady biofilter performance.