溶菌酶用量对天然橡胶加工性能的影响

在新鲜天然胶乳中添加不同用量的溶菌酶,对凝固后天然橡胶混炼胶的加工性能进行了研究。与酸凝固天然橡胶混炼胶相比,添加溶菌酶凝固天然橡胶混炼胶的弹性模量G’高,损耗因子tanδ小。当溶菌酶添加量为0.3%时,天然橡胶混炼胶弹性模量值最高,损耗因子值最小。通过对硫化特性参数的比较,天然胶乳加入溶菌酶凝固后具有比酸凝固胶样更快的硫化反应速率,且添加量为0.3%时,硫化速率最快。     

溶菌酶凝固天然橡胶加工性能和力学性能的研究

采用溶菌酶凝固天然胶乳,对凝固后天然橡胶的理化性能、加工性能及力学性能等进行研究,并与酸凝固天然橡胶对照。研究表明,溶菌酶凝固天然橡胶综合性能优异。溶菌酶凝固天然橡胶混炼胶与酸凝固天然橡胶混炼胶相比,弹性模量G’高,损耗因子tanδ小。与酸凝固天然橡胶相比,溶菌酶凝固天然橡胶蛋白质含量高,耐氧老化性能好,硫化速率快,硫化胶交联密度高,力学性能好。     

溶菌酶凝固天然橡胶加工性能和力学性能的研究

采用溶菌酶凝固天然胶乳,对凝固后天然橡胶的理化性能、加工性能及力学性能等进行研究,并与酸凝固天然橡胶对照。研究表明,溶菌酶凝固天然橡胶综合性能优异。溶菌酶凝固天然橡胶混炼胶与酸凝固天然橡胶混炼胶相比,弹性模量G’高,损耗因子tanδ小。与酸凝固天然橡胶相比,溶菌酶凝固天然橡胶蛋白质含量高,耐氧老化性能好,硫化速率快,硫化胶交联密度高,力学性能好。     

凝固方法对天然橡胶性能的影响

本文研究了凝固方法对天然橡胶性能的影响。结果表明:不同凝固方法制备的天然橡胶都达到5号标准橡胶的质量指标,生物凝固的天然橡胶硫化时间较短、硫化胶力学性能较好、而抗老化性能较差,HAc凝固的天然橡胶的硫化时间较长,硫化胶力学性能较差,而抗老化性能较好。     

偶联剂Si69用量对天然橡胶性能的影响

研究偶联剂Si69用量对天然橡胶性能的影响。结果表明:与未添加偶联剂Si69胶料相比,偶联剂Si69胶料的Payne效应降低,加工性能改善;邵尔A型硬度、100%定伸应力、300%定伸应力、拉伸强度和撕裂强度增大,拉断伸长率减小。随着偶联剂Si69用量增大,胶料的交联密度增大,抗硫化返原性提高;硫化胶的压缩温升呈下降趋势,抗湿滑性能降低,滚动阻力减小。     

环氧化天然橡胶加工性能的研究

研究了环氧化天然橡胶的塑炼，混炼，挤出及加工流变性能。结果表明，ＥＮＲ的加工性能与天然橡胶相近，只是塑炼效果胶ＮＲ稍差。ＥＮＲ混炼生热较低，吃粉速度较快，虽然挤出口型膨胀率大于ＮＲ，但挤出物外观与ＮＲ相当。     

加工方法对硫化天然橡胶结构与性能影响的研究

对天然胶乳及生胶所制备的硫化胶进行网络结构和性能测试 ,考察不同加工方法对硫化胶结构与性能影响。结果表明 ,胶乳胶膜的交联速率、效率、硫化胶强度及耐老化性能都比相应干胶的大 ;对普通硫化体系 ,生胶硫化胶的单、双硫键密度占总交联键密度的比例随硫化时间的延长有较大幅度增加 ,而配合胶乳胶膜的则变化不明显。     

酶辅助微生物凝固对天然橡胶性能的影响

采用酶辅助微生物凝固鲜胶乳提高天然橡胶产品性能,探究了酶用量对天然橡胶理化指标、硫化特性、加工性能、力学性能、机理及生热性能的影响。结果表明,随着酶用量的提高,生胶塑性初值和门尼黏度升高,塑性保持率降低;硫化胶正硫化时间(t₉₀)和焦烧时间(t₁₀)变短;生胶的弹性模量(G′)高,损耗因子(tan δ)小;硫化胶的拉伸强度、100%定伸应力及撕裂强度均呈上升趋势,老化处理后,硫化胶的力学性能同样保持升高的趋势;同时硫化胶温升呈下降趋势;此外,氮含量和凝胶含量有降低趋势,而丙酮溶物含量有升高趋势。     

微生物凝固天然橡胶与酸凝固天然橡胶的性能差异

为揭示微生物凝固天然橡胶(NR-w)和酸凝固天然橡胶(NR-a)的性能差别,制备了3个系列的NR,并对其性能进行了全面的研究.结果发现,在生胶性能方面,NR-w凝胶含量和塑性初值均高于NR-a,而分子量低于NR-a.对于硫化胶,NR-w纯胶硫化胶的力学性能远高于NR-a纯胶,而NR-w炭黑胶的力学强度与NR-a炭黑胶很接近;此外,NR-a纯胶的抗老化性能远高于NR-w,其炭黑胶的抗老化性能也高于NR-w,在硫化性能方面,NR-w的转矩增大速率快于NR-a,强度也比NR-a高.在动态性能方面,NR-w的抗湿滑性能和滚动阻力均高于NR-a.     

RPA分析硫黄用量对天然橡胶动态性能的影响

用橡胶加工分析仪(RPA)分析硫黄用量对NR动态性能的影响。结果表明:不同硫黄用量的混炼胶的动态模量随频率的升高和温度的降低而增加,损耗因子降低;应变超过28%,混炼胶的储能模量下降。不同硫黄用量的硫化胶随交联密度的提高,动态性能对频率的依赖性变小,对应变的依赖性变强;而温度越高,硫化胶的"橡胶弹性"越明显。     

复合保存剂HY/NH_3对天然橡胶加工性能的影响

采用单独含有NH_3、HY的天然橡胶作为对照样,与含有复合保存剂HY/NH_3的天然橡胶进行性能比较,利用红外光谱仪测定天然橡胶结构,橡胶加工分析仪测定其加工性能,核磁共振交联密度仪测其交联密度,研究复合保存剂HY/NH_3对天然橡胶性能的影响。结果表明,HY/NH_3几乎不影响生胶结构;在应变、温度扫描环境下,NY-1的弹性模量G’最大,损耗因子tanδ最小,NY-3居中;在频率扫描环境下,NY-3的弹性模量G’最大,损耗因子tanδ居中,NY-1的弹性模量G’居中,损耗因子tanδ最小;三种扫描环境下,NY-2的弹性模量G’均最小,损耗因子tanδ均最大;老化前,复合保存剂样品的总交联密度小于NH_3、HY样品的总交联密度;老化后,所有样品的总交联密度均变小。     

Rheological and processing properties of purified natural rubber

Studies were performed on the nature and magnitude of the variabilities in the rheological and processing properties of purified natural rubber (PNR). PNR samples were prepared from three clones of NR (RRIM 600, GT 1, and KRS 156). The corresponding whole NR (WNR) containing total nonrubber substances was also prepared for comparative purposes. All samples were stored for 3 months to elucidate the effect of storage on their rheological and processing properties. A novel study was also conducted to determine whether the commonly reported variabilities in the rheological properties had actual effects on the mixing. These were studied by means of an instrumented torque rheometer fitted with a small mixer head. The results showed that the vulcanization time of PNR was consistent and did not show clonal variation. PNR exhibited large clonal variation in the viscosity at a low shear rate and storage hardening, similar to the ordinary NR. However, the variations in the viscosity of PNR became less evident as the shear rates increased toward 200 s^?1. The significant findings were that the observed variations in the rheological properties had no practical effect on the mixing time of PNR samples with carbon black. Moreover, the PNR samples required less energy for mixing than their WNR counterparts. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 456–465, 2005     

改性油膏对天然橡胶加工性能和动态机械性能的影响

在70度天然橡胶配方中采用硫磺改性的油膏软化剂和不同粒径强炭黑配合,考察了不同配比对天然橡胶加工性能、动态力学性能和导热性能的影响。结果表明,填充改性油膏后,门尼粘度显著降低,焦烧时间延长约40 s,最高转矩、最低转矩均下降,加工性能变好。另外改性油膏和N774等量填充性能更优,除加工性能外,还具有良好的老化性能、动态力学性能和导热性能。     

Effect of the processing conditions and the addition of trans-polyoctenylene rubber on the properties of natural rubber/styrene–butadiene rubber blends

In this study, the influence of the processing conditions and the addition of trans-polyoctenylene rubber (TOR) on Mooney viscosity, tensile properties, hardness, tearing resistance, and resilience of natural rubber/styrene–butadiene rubber blends was investigated. The results obtained are explained in light of dynamic mechanical and morphological analyses. Increasing processing time produced a finer blend morphology, which resulted in an improvement in the mechanical properties. The addition of TOR involved an increase in hardness, a decrease in tear resistance, and no effect on the resilience. It resulted in a large decrease in the Mooney viscosity and a slight decrease in the tensile properties if the components of the compounds were not properly mixed. The results indicate that TOR acted more as a plasticizer than a compatibilizer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

碳纳米管的尺寸及用量对天然橡胶复合材料性能的影响

将碳纳米管（CNTs）添加到天然橡胶（NR）中制备了CNTs/NR复合材料,考察了CNTs的管径和用量对复合材料硫化特性、力学性能、动态力学性能和分散性的影响。结果表明,在管径相同时,随着CNTs用量的增大,复合材料的正硫化时间延长。随着CNTs用量的增大,复合材料的拉伸强度和扯断伸长率先增大后减小。相同管径件下,CNTs的用量越大,Payne效应越强,储能模量变化越大,损耗因子也越大;而在相同用量下,CNTs的管径越大,Payne效应越弱,储能模量变化越小,损耗因子也越小。当CNTs用量为15份、管径为80 nm时,其在NR基体中的分散性最好,复合材料的综合力学性能及动态力学性能最佳。     

硫化体系对天然橡胶性能的影响

采用常规硫化体系(CV)、半有效硫化体系(SEV)和有效硫化体系(EV)制备了不同的NR(天然橡胶)硫化胶。着重探讨了不同硫化胶的微观形貌、200%定伸强度、撕裂强度、拉伸强度、断裂伸长率和交联密度。研究结果表明:SEV硫化胶的微观形貌相对较好,填料能均匀分散在基体中;在其他条件保持不变的前提下,当w(NOBS)=w(硫)=2.0%(相对于NR质量而言)时,相应的未老化SEV硫化胶的撕裂强度(78 kN/m)相对最大;SEV硫化胶的交联密度大于CV硫化胶和EV硫化胶,并且适当增加交联密度能有效提高其综合性能,从而为开发新一代轮胎等复合材料奠定了基础。     

Effect of processing parameters on the vulcanisation of natural rubber using glutaraldehyde

The process ability of vulcanising natural rubber using glutaraldehyde at low temperature has been studied. The main objective of this work is to improve the properties and stability of natural rubber (NR) using glutaraldehyde as a curing agent. In this study, the vulcanised samples were prepared systematically and compared with sulphur cured natural rubber vulcanisates. The influence of mole ratio of ammonia and glutaraldehyde, and the processing parameters (i.e. curing time and temperature) was investigated. The cured NR based on glutaraldehyde exhibited better hardness and thermal properties than that of the NR cured from conventional sulphur system. The experimental results reveal that the properties of glutaraldehyde cured NR can be developed with the proper additives combination and conditions adopted in the preparation. This cured system is very interesting due to it can be used for high temperature industrial applications. Moreover, it eases of processing at low temperature and cost.