低蛋白天然橡胶的性能研究

分析了LPNR(低蛋白天然橡胶)和NR(天然橡胶)中的C、H、N和S元素的含量。结果表明，两者N元素的含量差异显著。而其它元素的含量差异不大；研究了LPNR和NR的弹性模量(G′)随频率变化和应变变化的响应曲线。结果表明，LPNR和NR的弹性模量随频率的增大而增大，随应变的增大而减小，在整个变化过程中LPNR的弹性模量比NR的弹性模量大；研究了LPNR和NR在N2中的热降解性能，发现LPNR的耐热性较NR的差。     

碳纳米管/天然橡胶复合材料的结构与性能

通过机械混炼法制备了碳纳米管(CNT)／天然橡胶(NR)复合材料,研究了CNT的预处理方式对复合材料结构与性能的影响。结果表明,与NR相比,CNT／NR复合材料的硫化返原现象减轻,硫化后凝胶质量分数降低,硫化剂用量应适当增加,由混酸氧化处理的CNT填充橡胶复合材料的硫化迟滞效应明显;复合材料内部存在CNT的富集区域和CNT含量很少的橡胶区域,CNT与NR之间的界面结合作用不好;由HF处理的CNT填充橡胶复合材料的整体性能最好,但受CNT在橡胶基体中的不良分散状态及界面性质的影响,其力学性能不高。     

白炭黑或埃洛石填充不同橡胶树品系天然橡胶复合材料的性能研究

分别采用白炭黑或埃洛石填充4种橡胶树品系（72059,PR107,73397和RRIM600）天然橡胶（NR）以制备复合材料,并研究复合材料的各项性能。结果表明：白炭黑或埃洛石填充NR复合材料的硫化特性受橡胶树品系的影响较小;两种填料填充的RRIM600复合材料均表现出最大的溶胀平衡交联密度和最优的物理性能,且50～70 ℃范围内的损耗因子最小,表明RRIM600复合材料的滞后损失最小,RRIM600满足低滚动阻力轮胎的用胶要求,而72059复合材料的相应性能较差;白炭黑填充72059复合材料的热稳定性最优,埃洛石填充各橡胶树品系NR复合材料的热稳定性差异不明显;PR107复合材料和73397复合材料的综合性能居中。     

天然橡胶与氯丁橡胶并用性能的研究

研究了天然橡胶与氯丁橡胶并用比例对硫化特性、力学性能、老化性能以及屈挠性能的影响,结果表明:天然橡胶改善了氯丁橡胶的加工性能,氯丁橡胶提高了天然橡胶的耐热空气老化性能以及耐臭氧老化性能,耐曲挠性能也有所改善.     

白炭黑补强异戊橡胶与天然橡胶的性能对比研究

对比研究白炭黑补强国产稀土异戊橡胶(IR)与天然橡胶(NR)的硫化特性、物理性能及动态力学性能。结果表明:与NR胶料相比,填充等量白炭黑的IR胶料的ts1和t90缩短,ML和MH减小;硫化胶的定伸应力和拉伸强度减小,拉断伸长率增大;当白炭黑用量为30份时,IR硫化胶的Payne效应最明显,剪切储能模量增大,剪切损耗模量减小,损耗因子增大,白炭黑在IR中的分散较差。     

改性白炭黑补强天然橡胶的性能研究

采用偶联剂Si69对白炭黑进行表面改性,研究改性白炭黑对天然橡胶胶料性能的影响。结果表明:与未改性白炭黑胶料相比,改性白炭黑胶料的加工安全性和硫化效率提升,硫化胶的300%定伸应力、拉伸强度、撕裂强度、耐磨性能和耐2级裂口屈挠性能提高,滚动阻力和动态生热性能略有改善,但抗湿滑性能略有下降;扫描电镜分析表明,改性白炭黑在橡胶基体中的分散性及其与橡胶基体的相容性改善。     

杜仲胶对天然橡胶性能影响的研究

研究了并入少量杜仲胶对天然橡胶硫化特性、力学性能以及疲劳性能的影响。结果表明,并入少量杜仲胶对天然橡胶硫化特性影响不大,可改善耐热空气老化性能,但拉伸强度有所降低,拉断伸长率变化不大,还可提高拉伸疲劳寿命和撕裂疲劳寿命。杜仲胶用量大于10份时,天然橡胶疲劳寿命有所下降;杜仲胶用量为7.5份时综合性能最好。     

芳纶短纤维增强天然橡胶复合材料性能研究

研究添加不同用量的芳纶短纤维/天然橡胶(NR)复合材料的性能。结果表明,NR复合材料的性能随着芳纶短纤维用量的增大先提高再下降;添加2份芳纶短纤维时复合材料的物理性能较好,磨耗性能也较优;添加芳纶短纤维能够使复合材料的抗湿滑性能变好,滚动阻力增大,导热性降低。     

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。     

5个橡胶树品系天然橡胶性能的研究

研究5个橡胶树品系天然胶乳的季节性干胶含量和天然橡胶(NR)的理化性质、贮存性能、硫化特性、物理性能。结果表明:各橡胶树品系胶乳的干胶含量随季节变化明显,其中GT1胶乳的平均干胶含量最大,且胶乳的干胶含量随季节波动最小;云研77-4和云研77-2 NR的贮存性能较好;GT1 NR的t90最短,RRIM600和云研77-4 NR的t90较长;GT1和PRI107 NR的物理性能较好。     

Cure characteristics and mechanical properties of hydrogenated natural rubber/natural rubber blends

The cure characteristics and mechanical properties of blends consisting of hydrogenated natural rubber (HNR) and natural rubber (NR) blends were investigated. The HNR/NR blends at 50/50 wt ratio were vulcanized using various cure systems: peroxide vulcanization, conventional vulcanization with peroxide, and efficient vulcanization with peroxide. The HNR/NR vulcanizates cured by the combination of peroxide and sulfur donor (tetramethylthiuram disulfide, TMTD) in the efficient vulcanization with peroxide exhibited the best mechanical properties. It was also found that the hydrogenation level of HNR did not affect the tensile strength of the vulcanizates. The tensile strength of the blends decreased with increasing HNR content because of the higher incompatibility to cause the noncoherency behavior between NR and HNR. However, the HNR/NR vulcanizate at 50/50 wt ratio showed the maximum ultimate elongation corresponding to a co‐continuous morphology as attested to by scanning electron micrographs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology,mechanical and viscoelastic properties of nitrile rubber/epoxidized natural rubber blends

A new class of blend membranes from blends of nitrile rubber (NBR) and epoxidized natural rubber (ENR) has been prepared and their morphology, miscibility, mechanical, and viscoelastic properties have been studied. The ebonite method was used to study the blend morphology of the membranes. The morphology of the blends indicated a two‐phase structure in which the minor phase is dispersed as domains in the major continuous phase. The performance of NBR/ENR blend membranes has been studied from the mechanical measurements. The viscoelastic behavior of the blends has been analyzed from the dynamic mechanical data. An attempt was made to relate the viscoelastic behavior with the morphology of the blends. Various composite models have been used to predict the experimental viscoelastic data. The area under the linear loss modulus curve was larger than that obtained by theoretical group contribution analysis. The homogeneity of the system was further evaluated by Cole–Cole analysis. Finally, a master curve for the modulus of the blend was generated by applying the time–temperature superposition principle. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1561–1573, 2005     

Rare earth compounds modified carbon black filled powdered natural rubber: Preparation,morphology and properties

Ten types of rare earth (RE) compounds modified carbon black (HAF‐RE) were prepared using chemical‐deposit method, then HAF‐RE were mixed with natural rubber latex to prepare HAF‐RE filled powdered natural rubber [P(NR/HAF‐RE)] by a carbon black/rubber latex coagulation method. It is found that most of the P(NR/HAF‐RE) vulcanizates showed better mechanical properties, especially higher tensile modulus, and tensile strength, compared with none‐rare earth modified carbon black filled powdered natural rubber [P(NR/HAF)]. Dysprosium (Dy) modified carbon black (HAF‐Dy) filled powdered natural rubber [P(NR/HAF‐Dy)] was chosen for intensive investigation because of its better comprehensive mechanical properties. It is found that the adding of Dy compounds could help to get smaller particles with narrower particle size distribution, and results from the SEM analysis show that carbon black has been dispersed in rubber matrix uniformly with diameter of 50–150 nm. The TEM analysis showed that Dy compounds could obviously reduce the aggregation of primary particles of carbon black, and promote the dispersion of carbon black in P(NR/HAF‐Dy) particles. © 2008 Wiley Periodicals, Inc. JAppl Polym Sci 2008     

Carbon black filled powdered natural rubber: Preparation,particle size distribution,mechanical properties,and structures

Carbon black (HAF) filled powdered natural rubber (P(NR/HAF)) was prepared and the particle size distribution, mechanical properties, and micromorphology of P(NR/HAF) were studied. A carbon black–rubber latex coagulation method was developed for preparing carbon black filled free‐flowing, noncontact staining NR powders with particle diameter less than 0.9 mm. A powdering mechanism model was put forward to describe the powdering process, which shows that the key technical points consist in the surfactant with good emulsification properties and the polymer coating resin with good film forming properties. SEM analysis shows that carbon black and rubber matrix have formed a macroscopic homogenization in the P(NR/HAF) particles without contact staining, and carbon black particles are well dispersed in rubber matrix with diameter of about 50–150 nm. P(NR/HAF) vulcanizate showed better mechanical properties than bale natural rubber/carbon black blends (NR/HAF) and simple NR latex/carbon black blends (NRL/HAF), which depends primarily upon the absence of free carbon black, the fine dispersion of filler on the rubber matrix, and the better interaction between carbon black and rubber matrix due to the proper preparation condition of noncontact staining carbon black filled powdered NR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1763–1774, 2006     

Effect of zinc oxide nanoparticles as cure activator on the properties of natural rubber and nitrile rubber

Zinc oxide (ZnO) nanoparticles were synthesized by homogeneous precipitation and calcination method and were then characterized by transmission electron microscopy and X‐ray diffraction analysis. Synthesized ZnO was found to have no impurity and had a dimension ranging from 30–70 nm with an average of 50 nm. The effect of these ZnO nanoparticles as cure activator was studied for the first time in natural rubber (NR) and nitrile rubber (NBR) and compared with conventional rubber grade ZnO with special reference to mechanical and dynamic mechanical properties. From the rheograph, the maximum torque value was found to increase for both NR and NBR compounds containing ZnO nanoparticles. ZnO nanoparticles were found to be more uniformly dispersed in the rubber matrix in comparison with the conventional rubber grade ZnO as evident from scanning electron microscopy/X‐ray dot mapping analysis. The tensile strength was observed to improve by 80% for NR when ZnO nanoparticles were used as cure activator instead of conventional rubber grade ZnO. An improvement of 70% was observed in the case of NBR. The glass transition temperature (T_g) showed a positive shift by 6°C for both NR and NBR nanocomposites, which indicated an increase in crosslinking density. The swelling ratio was found to decrease in the case of both NR and NBR, and volume fraction of rubber in swollen gel was observed to increase, which supported the improvement in mechanical and dynamic mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Study on variation of structure and properties of natural rubber during accelerated storage

The dynamic variations of molecular structure and properties of natural rubber (NR) during the accelerated storage have been studied. The results showed that, with the prolonging of the storage time, the average molecular weight and the gel content increased, the width index of molecular weight distribution decreased, the gel size increased gradually, but the crosslinking density of gel fluctuated only within a narrow range. Besides, the initial plasticity increased, whereas the plasticity retention index decreased. The studies with thermal analyses and infrared spectroscopy showed that the thermal degradation temperature dropped, the thermal degradation rate increased, and the thermal stability has decreased after the storage of NR. The molecular structure and properties of NR are in a state of dynamic variation during accelerate storage. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1779–1783, 1998     

无卤阻燃型天然橡胶的研究

该文研究了阻燃剂种类和用量对天然橡胶硫化胶的阻燃性能、力学性能和硫化特性的影响。结果表明：单用氢氧化铝时,随着用量增加,硫化胶阻燃性能上升,但力学性能有所下降,氢氧化铝用偶联剂A151表面改性处理后,硫化胶力学性能有所改善;红磷作为阻燃剂用量比较少,在提高硫化胶阻燃性的同时可改善其力学性能;氢氧化铝、红磷和三氧化二锑并用可产生较好的阻燃协同效果,同时会加快橡胶的硫化速度。     

天然虾青素改性白炭黑/天然橡胶复合材料的制备与性能

采用天然虾青素对白炭黑表面进行物理改性，并与天然橡胶（NR）制备成复合材料。利用RPA、DMA、SEM等测试手段对天然虾青素改性白炭黑/天然橡胶复合材料的结构与性能进行表征。结果表明，在硫化特性方面，与未采用天然虾青素改性白炭黑相比，采用天然虾青素改性白炭黑所得胶料的焦烧时间和工艺正硫化时间均缩短，促进了橡胶的硫化过程；在物理力学性能方面，所得硫化胶的拉伸强度基本不变，回弹性和耐磨性明显增加，压缩生热降低；在动态黏弹性方面，所得硫化胶的Payne效应明显降低，填料的分散性在一定程度上得到改善；在动态力学性能方面，所得硫化胶的滚动阻力降低，玻璃化转变温度提高。特别地，在耐老化方面，天然虾青素改性白炭黑/天然橡胶复合材料的耐热空气老化性能明显提高。     

Mechanical properties of natural rubber/grafted cellulose fibre composites

Mechanical properties of natural rubber/allyl acrylate and allyl methacrylate grafted cellulose fibre composites are presented. Stress/strain measurements and dynamic mechanical measurements indicate that the adhesion between grafted fibres and matrix is better than that in samples containing untreated cellulose fibres. This makes it possible to vary the composite properties by varying the fibre type and/or fibre amount.     

Effect of phenol functionalization of carbon nanotubes on properties of natural rubber nanocomposites

This paper reports the results of studies on the effect of phenol functionalization of carbon nanotubes (CNTs) on the mechanical and dynamic mechanical properties of natural rubber (NR) composites. Fourier transform infrared spectrometry (FTIR) indicates characteristic peaks for ether and aromatic rings in the case of phenol functionalized CNT. Although differential scanning calorimetric (DSC) studies show no changes in the glass‐rubber transition temperature (T_g) of NR in the nanocomposites due to surface modification of CNT, dynamic mechanical studies show marginal shifting of T_g to higher temperature, the effect being pronounced in the case of functionalized CNT. Stress‐strain plots suggest an optimum loading of 5 phr CNT in NR formulations and the phenolic functionalization of CNT does not affect significantly the stress‐strain properties of the NR nanocomposites. The storage moduli register an increase in the presence of CNT and this increase is greater in the case of functionalized CNT. Loss tangent showed a decrease in the presence of CNT, and the effect is more pronounced in the case of phenol functionalized CNT. Transmission electron microscopy (TEM) reveals that phenol functionalization causes improvement in dispersion of CNT in NR matrix. This is corroborated by the increase in electrical resistivity in the case of phenol functionalized CNT/NR composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012