Mechanical properties of siliceous earth/natural rubber composites

Siliceous earth (SE), which has a special morphology and structure, was selected as filler of natural rubber (NR) and mechanical properties of compounds were analyzed. Two processes were employed to prepare SE/NR compounds described as mechanical mixing method and latex method, respectively. Cure characteristics, mechanical properties of the vulcanizates prepared from the masterbatches were compared with those prepared by mechanical mixing method. X‐ray diffraction results of NR/SE vulcanizations indicated that mechanical mixing above the latex process facilitated the intercalation of NR into the galleries of SE. The results of mechanical properties show that SE has good reinforcing properties on NR both by latex or mechanical mixing process. By comparison, H samples show slightly higher crosslink density, tensile strength, 300% modulus, and lower elongation at break than M sample in same loading. But in the aspect of dynamic properties there exist obviously difference between latex and mechanical mixing process. Rubber processing analyzer (RPA) results showed that uncured M samples showed obviously higher storage modulus than that of H samples. The heat build‐up of M30 is much lower than that of H30. These behaviors indicated better dynamitic properties when the masterbatches prepared by the predispersing method was utilized. POLYM. ENG. SCI., 58:1043–1052, 2018. © 2017 Society of Plastics Engineers     

湿法制备硅土/白炭黑/天然橡胶复合材料及性能

分别制备改性白炭黑和硅土悬浮液,然后与天然胶乳混合,得到白炭黑和硅土天然橡胶母炼胶。在混炼阶段将两种母炼胶按不同比例混合,得到一系列总填料份数为40 phr的混炼胶。硫化特性测试结果表明：当白炭黑中加入一定量硅土时,有利于改善NR硫化初期的流动性,硫化速率增大。RPA测试结果表明：在白炭黑中加入一定量的硅土,能显著提高填料在天然橡胶基体中的分散性,payne效应明显下降。加入硅土后硫化胶的tanδ均低于白炭黑,滚动阻力下降。物理性能测试结果表明：拉伸强度、300%定伸应力、撕裂强度均随着硅土加入的份数增加而增大。白炭黑与硅土并用时的扯断伸长率明显高于单独硅土或白炭黑填充橡胶。     

环氧化天然橡胶改性的丁苯橡胶/白炭黑复合材料的形态和性能

以环氧化天然橡胶为改性剂制备了丁苯橡胶/白炭黑复合材料,研究了环氧化天然橡胶对丁苯橡胶/白炭黑复合材料微观形态和力学、耐热、耐老化及动态力学性能的影响.结果表明,少量环氧化天然橡胶的加入改善了填料在橡胶基质中的分散,提高了丁苯橡胶/白炭黑复合材料硫化胶的定伸应力、拉伸强度、撕裂强度和耐磨性能,降低了其动态压缩疲劳生热速...     

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     

The effect of peroxide crosslinking on thermal,mechanical, and rheological properties of polycaprolactone/epoxidized natural rubber blends

Polycaprolactone (PCL)/epoxidized natural rubber (ENR) blends (PCL/ENR = 70/30, 50/50 wt/wt) were prepared by a melt mixing in an internal mixer in the presence of a small amount (0.5 and 1 phr) of dicumyl peroxide. The effect of peroxide crosslinking on thermal, mechanical, and rheological properties of the blends was investigated by means of DSC, tensile test, and small amplitude oscillating rheometer, respectively. It was revealed that peroxide crosslinking enhanced degree of crystallinity of PCL phase and its non-isothermal melt crystallization temperature. The crosslinked blends behave like a thermoplastic elastomer exhibiting high elongation-at-break and fairly good elastic recovery as well as melt processibility. From melt rheological analysis, the peroxide crosslinked blends showed more pronounced shear thinning effect and higher elasticity compared to simple blends.     

环氧化天然橡胶原位接枝SiO_2制备天然橡胶复合材料的力学性能和阻尼特性

采用环氧化天然橡胶(ENR)原位接枝SiO_2母胶制备NR/ENR/SiO_2复合材料,考察NR/ENR/SiO_2复合材料的力学性能和阻尼特性。结果显示,添加环氧化天然橡胶原位接枝SiO_2母胶的NR/ENR/SiO_2复合材料比单独添加环氧化天然橡胶和SiO_2的样品分散性更好、硫化速率更高、力学性能升高明显,且耐老化性能得到改善。添加ENR原位接枝SiO_2母胶的NR/ENR/SiO_2复合材料与对照样相比,玻璃化转变温度升高,有效阻尼温域扩宽,阻尼性能提高。     

Self‐crosslinkable lignin/epoxidized natural rubber composites

Self‐crosslinkable lignin/epoxidized natural rubber composites (SLEs) were prepared through a high‐temperature dynamic heat treatment procedure followed by a postcuring process. Because of the ring‐opening reaction between lignin and epoxidized natural rubber (ENR), lignin as a crosslinker and reinforcing filler was uniformly dispersed into the ENR matrix and was highly compatible with the polymer matrix; this was confirmed by scanning electron microscopy. The curing behavior, mechanical properties, and dynamic mechanical properties of the SLEs were studied. The results show that the crosslinking degree, glass‐transition temperature, modulus, and tensile properties of the SLEs substantially increased with the addition of lignin. A physical model was used to verify the strong interactions between lignin and ENR. Stress–strain curves and X‐ray diffraction suggested that the reinforcement effect on the SLEs mainly originated from lignin itself rather than from strain‐induced crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41166.     

Thermal and mechanical properties of epoxidized natural rubber modified epoxy matrices

Two sets (A and B) of bisphenol A–diglycidyl ether (DGEBA) based epoxy resin formulations were modified with epoxidized natural rubber (ENR 50) and its liquid version (LENR 50), and cured with amino propoxylate initiator/accelerator at ambient temperatures. The ENR 50 loading range was 1.6–5.9 wt%. Both sets could be loaded up to 12 wt% with LENR 50. Significant improvements in tensile toughness and impact toughness could only be observed for set A formulations. At the maximum LENR 50 loading achieved, the improvement in tensile toughness is 250% in comparison with that of the neat formulation; that for impact toughness is 125%. Differential scanning calorimetry reveals multiple transitions, characteristic of these systems. Scanning electron micrographs of fractured surfaces show uniform rubber dispersions in the submicrometre size range. At the loading levels used, LENR 50 particle dispersions fall within the range of 0.33–0.47 µm in size; those of ENR 50 are 0.48–0.67 µm in average size. Improvements in toughness are similar for both versions of epoxidized natural rubber. For both LENR 50 and ENR 50 modified epoxy systems, the extremes of 0.80 (set A) and 1.95 (set B) in glycidyl ether/reactive hydrogen molar ratios considered show distinct failure mechanisms, that of ductile failure with yielding in the former and brittle failure in the latter, irrespective of reactive diluent content. © 1999 Society of Chemical Industry     

Physical properties of natural rubber/organoclay nanocomposites compatibilized with epoxidized natural rubber

Onium ion‐modified montmorillonite (organoclay) was melt compounded with natural rubber (NR) in an internal mixer and cured by using a conventional sulfuric system. Epoxidized natural rubber with 50 mol % epoxidation (ENR 50) was used in 10 parts per hundred rubber (phr) as a compatibilizer. The effect of organoclay with different filler loading up to 10 phr was studied. Cure characteristics were determined by a Monsanto MDR2000 rheometer, whereas the tensile, compression, and tear properties of the nanocomposites were measured according to the related ASTM standards. While the torque maximum and torque minimum increased slightly, both scorch time and cure time reduced with the incorporation of organoclay. The tensile strength, elongation at break, and tear properties went through a maximum (at about 2 phr) as a function of the organoclay content. As expected, the hardness, moduli at 100% (M100) and 300% elongations (M300) increased continuously with increasing organoclay loading. The compression set decreased with incorporation of organoclay. The dispersion of the organoclay in the NR stocks was investigated by X‐ray diffraction and transmission electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1083–1092, 2006     

Synergistic effect of graphene with graphene oxide,nanoclay, and nanosilica in enhancing the mechanical and barrier properties of bromobutyl rubber/epoxidized natural rubber composites

The present work aims to investigate the effect of hybrid nanofillers in bromobutyl rubber/epoxidized natural rubber (ENR 50) composites for developing highly air-impermeable nanocomposites. The nanocomposites with hybrid nanofillers were prepared by a simple melt mixing method, and the morphology of the developed nanocomposites was studied using X-Ray diffraction, transmission electron microscopy, and atomic force microscopy. Improvement in the mechanical, barrier and dynamic properties can be observed for hybrid nanocomposites compared to the composites filled with individual graphene nanoplatelets (GNPs). The strong interfacial attraction between GNP monolayers enhance its aggregation in nanocomposites. While, in the current study the results are showing that the addition of graphene oxide, nanoclay, and nanosilica enhances the dispersion of GNP in the composites. The homogeneous dispersion of GNP nanofillers will develop a tortuous pathway in the composites, which are responsible for their air barrier properties. Bound rubber content and dynamic strain measurements (Payne effect) show a maximum value for binary nanocomposites.     

High‐performance bio‐based poly(lactic acid)/natural rubber/epoxidized natural rubber blends: effect of epoxidized natural rubber on microstructure,toughness and static and dynamic mechanical properties

Attempts have been made to prepare high‐performance bio‐based blends through blending of poly(lactic acid) (PLA) with natural rubber (NR) in the presence of epoxidized natural rubber (ENR) as a compatibilizer. The prepared samples were characterized using differential scanning calorimetry, measuring the tensile properties and impact resistance, scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMTA). Morphological studies revealed a matrix‐dispersed morphology for all blends, in which the average droplet size significantly decreased with the use of ENR. The elongation at break and impact strength of the blend containing 3 wt% ENR were 45 and 16 times those of neat PLA, respectively. These values are significantly higher than those previously reported for various simple and dynamically vulcanized rubber‐toughened PLAs. The influence of ENR on compatibility was confirmed by rheological tests, FTIR spectra and DMTA. DMTA also showed a marked increase in elastic modulus for the blend in the presence of 3 wt% ENR. The tensile properties and impact resistance were directly dependent on the ENR content and rubber droplet size. © 2018 Society of Chemical Industry     

天然胶乳/炭黑复合材料的动态力学性能研究

通过添加阴离子表面活性剂,制备了稳定性能优异的炭黑分散液;然后将其添加到天然胶乳(NRL)中,采用胶乳共沉法制备NRL/炭黑复合材料,并对其物理性能、动态力学性能和内生热等进行了探讨。研究结果表明:当炭黑类型相同时,由胶乳共沉法制备的硫化胶之力学性能普遍优于由机械法制备的硫化胶;当采用炭黑N375补强时,由胶乳共沉法制备的硫化胶之力学性能相对最佳,其拉伸强度、撕裂强度和硬度分别比由机械法制备的硫化胶提高了6.5%、4.6%和8.8%;由胶乳共沉法制备的硫化胶之损耗因子(tanδ)小于由机械法制备的硫化胶,故前者的滞后损失更小、内生热更少且温升更低。     

环氧化天然橡胶共混物与复合材料

综述了国内外环氧化天然橡胶(ENR)共混物与复合材料的研究现状和应用发展趋势。介绍了几种环氧化天然橡胶共混物与复合材料的优点及影响其性能的因素。     

天然橡胶/改性纳米碳酸钙复合材料的形态与力学性能

比较了3种改性纳米碳酸钙,如硬脂酸改性的纳米碳酸钙(CCR)、CCR的固相改性纳米碳酸钙(M—CCR)、悬浮改性纳米碳酸钙(M—CaCO3)与天然橡胶组成的复合材料硫化胶的力学性能和形态。结果表明,3种复合材料的硫化胶与天然橡胶硫化胶相比,其力学性能得到了明显改善,其中含有M—CaCO3的复合材料力学性能的提高和形态的改善优于含有CCR和M—CCR者。     

Effects of coagulation processes on properties of epoxidized natural rubber

The epoxidized natural rubber (ENR) with epoxy group contents of 48.4% were coagulated with ethanol and steam and the structures, processing performances, antioxidative behaviors, cure characteristics, and dynamic mechanical properties were analyzed using infrared spectroscopy, rubber processing analyzer, thermogravimetric analyzer, rheometer, and dynamic thermomechanical analyzer, respectively. The results indicate that the ENR coagulated with ethanol (ENR‐e) exhibits a compact structure and the contents of residual low‐molecular‐weight matters are higher than those of unconsolidated ENR coagulated with steam (ENR‐s). Therefore, the processing performance and antioxidative behavior as well as the curing characteristics of ENR‐e compound are poorer than those of ENR‐s. Although the mechanical properties and wet skid resistance of ENR‐s vulcanizate are poorer than those of ENR‐e, the heat build‐up or rolling resistance of ENR‐s is better than that of ENR‐e. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal aging on mechanical properties and crosslinked network of natural rubber/zinc Dimethacrylate composites

This article dealt with the relationship between mechanical properties and crosslinked networks of natural rubber (NR) reinforced by zinc dimethacrylate (ZDMA) after thermal aging. After thermal aging at the present experimental conditions, the covalent crosslink density showed a decrease all the time, whereas the ionic crosslink density was stable at 80°C but decreased at a higher temperature. The decrease in the total crosslink density after aging indicates the degradation of the crosslinked network. However, an experimental phenomenon observed was that the tensile strength and tear strength increased in a certain degree after aging at 80°C or at a 100°C for a short time. In addition, the thermal stability of the NR/ZDMA composite was evaluated by thermal gravimetric analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

淀粉/天然橡胶复合材料的力学性能研究

采用不同偶联剂对淀粉活化改性,通过直接共混法制备淀粉/天然橡胶复合材料。研究了淀粉种类、添加量及偶联剂对复合材料的拉伸性能、硬度、耐磨性的变化规律。结果表明:改性后淀粉/天然橡胶复合材料的拉伸性能、硬度、耐磨性明显增加,而改性后木薯淀粉/天然橡胶复合材料的力学性能最佳;采用质量分数为3%的有机硼偶联剂对橡胶材料的改性效果最好。     

The effect of epoxidized vegetable oil and phthalic anhydride as compatibilizers on properties of rubber seed shell/polypropylene composites

Iranian Polymer Journal - Numerous adverse effects are reported from excessive usage of synthetic polyolefins including major environmental concerns. Since then, the development of natural-based...     

环氧化天然橡胶贮存性能的差异

对环氧化天然橡胶（ENR）及其胶乳（ENRL）进行了为期2年的贮存试验,考察其外观和主要物理性能的变异状况,探讨了这些性状变异的机理,了解到ENR和ENRL原材料长期贮存,其外以观无明显变化。     

环氧化天然橡胶贮存性能的变异

对环氧化天然橡胶 (ENR)及其胶乳 (ENRL)进行了为期 2年的贮存试验 ,考察其外观和主要物理性能的变异状况 ,探讨了这些性状变异的机理 ,了解到ENR和ENRL原材料长期贮存 ,其外观无明显变化。