Styrene butadiene rubber-short nylon fiber composites

The cure characteristics and mechanical properties of short nylon fiber reinforced styrene butadiene rubber were studied at varying fiber concentration. The plasticity of the composite was adversely affected by nylon short fibers. The minimum torque increased with fiber concentration. Scorch time and cure time showed a reduction in presence of short fibers. The tensile strength, tear strength, elongation at break and abrasion resistance were studied in both the orientation of fibers. Tensile strength, tear strength and abrasion resistance increased with fiber concentration and were higher in the longitudinal direction. Resilience showed a reduction with fiber content and compression set increased with fiber loading.     

Cure Characteristics and Mechanical Properties of Short Nylon Fiber Reinforced Natural Rubber–Reclaimed Rubber Blends

Cure characteristics and mechanical properties of short nylon fiber reinforced natural rubber–reclaimed rubber blend was studied. Minimum torque, maximum–minimum torque and cure rate were increased by the addition of fiber. Tensile and tear properties were enhanced by the addition of fibers. Introduction of fibers decreased the resilience and abrasion loss. Heat build up and compression set were higher for the composites.     

Styrene butadiene rubber/reclaimed rubber blends

Cure characteristics and mechanical properties of styrene butadiene rubber reclaimed rubber blends were studied. The blends showed improved processability, as indicated by the minimum torque values. Cure characteristics like minimum torque, (maximum-minimum) torque, cure time and cure rate decreased in the presence of reclaimed rubber. Tensile strength, tear strength, elongation at break were higher for blends. Resilience decreased with reclaim content. Compression set and abrasion loss were higher in the blends.     

Short fiber-reinforced thermoplastic elastomers from blends of natural rubber and polyethylene

Thermoplastic elastomer blends of natural rubber (NR) with high density polyethylene (HDPE) and with low density polyethylene (LDPE) were reinforced with short silk fiber. Processing characteristics such as torque and temperature developed during mixing and the effect of processing parameters such as nip gap and number of passes in the mill necessary to secure maximum orientation of the fibers in the blends were studied. A small nip gap and a single pass in the mill were found to give best results. Of the different mixing sequences studied, the sequence where short fibers followed by rubber were added to the molten thermoplastic was found to give a uniform dispersion of fibers. Fiber breakage and the change in aspect ratio of the fibers after mixing were also examined. It was observed that, as a direct consequence of the mixing sequence, each fiber was coated with a layer of thermoplastic. Although the properties improved on the addition of the dry bonding system of silica–resorcinol–hexamethylenetetramine, the comparatively long curing time required for full development of adhesion between the fibers and the matrix proved to be a major disadvantage associated with the incorporation of the bonding system. The tensile and tear properties were substantially enhanced, but the ultimate elongation decreased sharply with increasing loading of short fibers in the blends. The effect of fiber orientation and the development of anisotropy in the properties was also noted. Scanning electron microscopy (SEM) studies of the benzene-extracted surfaces of the NR/HDPE (high density polyethylene) blends substantiated the theory of fibers behaving like “mechanical anchors” between the rubber and thermoplastic phase. The effect of fiber loading on the tear and tensile properties of the blends of NR/LDPE with varying blend ratios was studied. Most pronounced improvement in the properties on the addition of short fibers was observed in the high rubber blends. As the plastic content in the blends increased, the short fibers were found to have a lesser influence on the properties. SEM photomicrographs of the tensile and tear fracture surfaces indicated the fiber orientations and the effect of orientation, fiber loading, and blend ratios on the nature of fracture.     

Scanning Electron Microscopy Studies on Tear and Wear Failure of Short Kevlar Fiber-Thermoplastic Polyurethane Composite

Abstract

Tear and wear properties of short kevlar fiber, Thermoplastic polyurethane (TPU) composite with respect to fiber loading and fiber orientation has been studied and the fracture surfaces were examined under scanning electron microscope (SEM). Tear strength first decreased up to 20 phr fiber loading and then gradually increased with increasing fiber loading. Anisotropy in tear strength was evident beyond a fiber loading of 20 phr. Tear fracture surface of unfilled TPU showed sinusoidal folding characteristic of high strength matrix. At low fiber loading the tear failure was mainly due to fibermatrix failure whereas at higher fiber loading the failure occurred by fiber breakage. Abrasion loss shows a continuous rise with increasing fiber loading, the loss in the transverse orientation of fibers being higher than that in the longitudinal orientation. The abraded surface showed long cracks and ridges parallel to the direction of abrasion indicating an abrasive wear mechanism. In the presence of fiber, the abrasion loss was mainly due to fiber loss.     

Mechanics of short fibers in filled styrene-butadiene rubber (SBR) composites

Different short fibers (glass, carbon, cellulose, polyamide, and polyester with aspect, length/diameter, ratio of 600, 860, 500, 83, and 330 respectively) were added to styrene-butadiene rubber (SBR) matrix filled with an inorganic semireinforcing mineral (sepiolite). In all cases, 18 parts by volume of fiber per 100 parts by mass of rubber were added. The fiber orientation attained (more than 60%) was evaluated by a ratio of directional mechanics on uncured samples. In glass and carbon fiber composites, because of decreases in fiber aspect ratio after mixing (10 and 35 respectively), no improvements in properties were obtained. The presence of fibers yields a large increase in green strength, stress at low strain, and tear strength. Logically, the elongation at break diminishes. The uncured and cured properties present a remarkable anisotropy. The adhesive employed (resorcinol-formaldehyde) to increase fiber-to-matrix adhesion enhanced the composite properties, especially in the case of polyester fiber composites. Thus, for polyester fiber composites, green strength became 15.85 kg/cm²; stress at 25% strain, 10.2 MPa; tensile strength, 6.3 MPa; elongation at break, 36%; tear strength, 70 N; and swelling in longitudinal direction, 1.06.     

溶聚丁苯橡胶/炭黑/短纤维复合材料的取向结构与力学性能

研究了溶聚丁苯橡胶(SSBR)／炭黑／短纤维复合材料(SFRC)的力学性能和短纤维在橡胶中的取向度及其黏合效果,分析了短纤维的黏合作用对复合材料应力．应变形为的影响。结果表明,短纤维的加入显著提高了SFRC的撕裂强度、10％定伸应力及邵尔A型硬度;短纤维用量小于30份时。2种预处理短纤维的取向度呈增长趋势,且尼龙短纤维的取向度明显高于聚酯短纤维;SFRC在平行方向上有不同程度的屈服现象,且添加聚酯短纤维的SFRC屈服应变及应力值小于添加尼龙短纤维的SFRC。SFRC在垂直方向没有应力屈服现象;预处理短纤维与橡胶的黏合效果优于未处理短纤维。     

Effect of an epoxy‐based bonding agent on the cure characteristics and mechanical properties of short‐nylon‐fiber‐reinforced acrylonitrile–butadiene rubber composites

The cure characteristics and mechanical properties of short‐nylon‐fiber‐reinforced acrylonitrile–butadiene rubber composites with and without an epoxy resin as a bonding agent were studied. The epoxy resin was a good interfacial‐bonding agent for this composite system. The minimum torque showed a marginal increase with the resin concentration. The maximum–minimum torque showed only a marginal change with the resin. The scorch time decreased with the fiber concentration and resin content. The tensile strength and abrasion resistance were improved and the tear resistance and resilience were reduced with the resin concentration. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 532–539, 2006     

Aramid‐short‐fiber reinforced rubber as a tire tread composite

Mechanical and dynamic‐mechanical properties of a typical tire tread compound reinforced with one part aramid short fibers were investigated in order to predict the effects of fibers on tire tread performances such as rolling resistance and traction. Rubber processing, including mixing and extrusion, was performed in an industrial scale. Fiber orientation as a result of extrusion was evaluated quantitatively and qualitatively using mechanical anisotropy in swelling and scanning electron microscopy, respectively. Unidirectional tensile tests revealed higher modulus, but slightly lower strength and elongation at break for the composites stretched in the longitudinal (orientation) and transverse directions than those for the isotropic reference compound with no fiber. Dynamic mechanical thermal analysis showed that relative values of loss factor for the longitudinal and transverse composites and the reference compound depended on the state of polymer as glassy or rubbery. Therefore, a high loss factor at lower temperatures and a low loss factor at higher temperatures predicted a balanced improvement of tire traction and rolling resistance as a result of fiber addition. Heat build‐up and abrasion experiments showed that addition of fiber did not deteriorate other performances of tire tread. Also, the fibers had negligible effects on processing and vulcanization characteristics of the composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Cure Characteristics and Mechanical Properties of Short Nylon-6 Fiber Neoprene Rubber Composite Containing Epoxy Resin as Bonding Agent

ABSTRACT

Cure characteristics and mechanical properties of the short nylon fiber reinforced neoprene rubber with and without epoxy bonding agent at various fiber loadings were studied. The fiber loading was varied from 0 to 30 phr and the resin content was in the range 0 to 5 phr. Minimum torque and cure time were increased in the presence of resin. Mechanical properties like tensile strength and abrasion resistance showed an increase with resin concentration. It was found that epoxy based bonding agents enhanced the properties of short nylon fiber reinforced neoprene rubber.     

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     

Synthesis and Characterization of Conducting Composites of Polypyrrole/Polypyrrole-Coated Short Nylon Fiber and Natural Rubber

Pyrrole was polymerized in the presence of anhydrous ferric chloride as oxidant and p-toluene sulphonic acid as dopant. Polypyrrole-coated short Nylon fibers were prepared by polymerizing pyrrole in the presence of short Nylon fibers. The resultant polypyrrole (PPy) and polypyrrole-coated Nylon fiber (F-PPy) were characterized using SEM and then used to prepare rubber composites based on natural rubber. The cure pattern, cure kinetics, filler dispersion, DC conductivity, mechanical properties and morphology of the resulting composites were studied. The presence of PPy-coated fibers in the natural rubber/PPy system reduced the cure time significantly. The DC conductivity of the composites was found to be better for the F-PPy system compared to PPy-filled NR composite. The F-PPy system also showed better tensile strength, modulus and tear resistance.     

Natural rubber composites reinforced with sisal/oil palm hybrid fibers: Tensile and cure characteristics

Natural rubber was reinforced with untreated sisal and oil palm fibers chopped to different fiber lengths. The influence of fiber length on the mechanical properties of the hybrid composites was determined. Increasing the fiber length resulted in a decrease in the properties. The effects of concentration on the rubber composites reinforced with sisal/oil palm hybrid fibers were studied. Increasing the concentration of fibers resulted in a reduction in the tensile strength properties and tear strength but an increase in the modulus of the composites. Fiber breakage analysis was evaluated. The vulcanization parameters, processability characteristics, and stress–strain properties of these composites were analyzed. The extent of fiber alignment and the strength of the fiber–rubber interface adhesion were analyzed from the anisotropic swelling measurements. Scanning electron microscopy studies were performed to analyze the fiber/matrix interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2305–2312, 2004     

Curing characteristics and mechanical properties of alkali‐treated grass‐fiber‐filled natural rubber composites and effects of bonding agent

To improve adhesion between fiber and matrix, natural rubber was reinforced with a special type of alkali‐treated grass fiber (Cyperus Tegetum Rox b). The cure characteristics and mechanical properties of grass‐fiber‐filled natural rubber composites with different mesh sizes were studied with various fiber loadings. Increasing the amount of fibers resulted in the composites having reduced tensile strength but increased modulus. The better mechanical properties of the 400‐mesh grass‐fiber‐filled natural rubber composite showed that the rubber/fiber interface was improved by the addition of resorcinol formaldehyde latex (RFL) as bonding agent for this particular formulation. The optimum cure time decreased with increases in fiber loading, but there was no appreciable change in scorch time. Although the optimum cure time of vulcanizates having RFL‐treated fibers was higher than that of the other vulcanizates, it decreased with fiber loading in the presence of RFL as the bonding agent. But this value was lower than that of the rubber composite without RFL. Investigation of equilibrium swelling in a hydrocarbon solvent was also carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3151–3160, 2006     

CURE CHARACTERISTICS AND MECHANICAL PROPERTIES OF NATURAL RUBBER/RECLAIMED RUBBER BLENDS

Cure characteristics and mechanical properties of natural rubber/reclaimed rubber blends were studied. The minimum torque values of the blends were lower than that of the gum compound. The (maximum–minimum torque) and scorch time decreased with increasing reclaim content. The cure rate of the blends were lower than that of the virgin compounds. The tear strength was improved by the addition of reclaimed rubber. Tensile strength, elongation at break, and resilience decreased with increasing reclaim loading. The heat buildup was higher for the blends.     

聚酯短纤维增强丁腈橡胶硫化胶的压缩性能

研究了聚酯短纤维用量对丁腈橡胶(NBR)混炼胶的流变性、硫化胶的力学性能、压缩应力-应变、压缩应变弛豫、压缩永久变形、冲击回弹性等的影响。结果表明:随着聚酯短纤维用量的增大,NBR混炼胶硫化过程中的最小转矩逐渐增大;NBR硫化胶的压缩永久变形、回弹性逐渐增大,拉伸强度、扯断伸长率逐渐减小。在增强填料量相同的情况下,填充聚酯短纤维的NBR混炼胶的最小转矩比填充炭黑的小,其NBR硫化胶的刚度比填充炭黑的大。     

Cure Characteristics and Mechanical Properties of HRH Bonded Nylon-6 Short Fiber-Nanosilica-Acrylonitrile Butadiene Rubber Hybrid Composite

Nano silica was synthesized by acid hydrolysis of sodium silicate using diluted hydrochloric acid. This synthetic nanosilica was used in place of hydrated silica in a HRH (hexamethylenetetramine, resorcinol and silica) bonding system for acrylonitrile butadiene rubber–nylon-6 short fiber composite. Nanosilica was also used as a reinforcing filler in acrylonitrile butadiene rubber–nylon-6 short fiber hybrid composite. Cure characteristic and mechanical properties of the hybrid composites were evaluated. Minimum torque, maximum torque, and cure time of the hybrid composites increased with silica loading. Cure rate increased with fiber loading and decreased with silica content. Scorch time also decreased with fiber loading and silica content. Volume fraction of rubber in a solvent-swollen sample increased with nanosilica. The efficiency of the HRH dry bonding system was improved in the presence of nanosilica. Nanosilica in the rubber composites also improved the tensile strength, modulus, and tear strength better than the conventional silica composites. Abrasion loss, hardness, resilience, and compression set properties were also better for the nano silica composites. The composites showed anisotropy in mechanical properties.     

短纤维-橡胶复合材料的混炼工艺

研究了转子转速和短纤维用量对短纤维-橡胶复合材料混炼过程及硫化胶质量的影响。结果表明,随着转子转速和短纤维用量的增加,混炼过程中消耗的最大功率、单位能耗等增加,当转子转速为70r/min,聚酯短纤维用量为3份时,硫化胶的拉伸强度、撕裂强度等物理机械性能出现最佳值。     

Short sisal fiber reinforced styrene-butadiene rubber composites

Styrene-butadiene rubber (SBR) composites were prepared by incorporating short sisal fibers of different lengths and concentrations into the SBR matrix in a mixing mill according to a base formulation. The curing characteristics of the mixes were studied and the samples were vulcanized at 150°C. The properties of the vulcanizates such as stress-strain behavior, tensile strength, modulus, shore-A hardness, and resilience were studied. Both the cured and uncured properties showed a remarkable anisotropy. It has been found that aspect ratio in the range of 20–60 is effective for sufficient reinforcement. The mechanical properties were found to increase along and across the grain direction with the addition of fibers. The effects of fiber length, orientation, loading, type of bonding agent, and fiber-matrix interaction on the properties of the composites were evaluated. The extent of fiber orientation was estimated from green strength measurements. The adhesion between the fiber and the rubber was enhanced by the addition of a dry bonding system consisting of resorcinol and hexamethylene tetramine. The bonding agent provided shorter curing time and enhanced mechanical properties. The tensile fracture surfaces of the samples have been examined by scanning electron microscopy (SEM) to analyze the fiber surface morphology, orientation, fiber pull-out, and fiber-matrix interfacial adhesion. Finally, anisotropic swelling studies were carried out to analyze the fiber-matrix interaction and fiber orientation. © 1995 John Wiley & Sons, Inc.     

Tear and processing behaviour of short sisal fibre reinforced styrene butadiene rubber composites

The tear failure and processing characteristics of short sisal fibre reinforced styrene butadiene rubber (SBR) composites were investigated. Tear strength was examined with special reference to the effects of fibre length, fibre orientation, fibre concentration and bonding agent. It was observed that the tear strength depends on all the above factors. The tear failure mechanism was analysed from fractographs taken using a scanning electron microscope (SEM). During tear testing, the composites failed by a shearing process. Microscopic examination of cracks propagating in SBR composites revealed that the amorphous SBR matrix developed cracks, leaving ligaments of rubber attached to the broken fibres. The rubber particles were stretched as the crack opened and failure occurred at large critical extensions. It was observed that an increase in the concentration of fibres increased the tear strength in both longitudinal and transverse directions. The tear strength values were almost three to four times higher than those of the unfilled vulcanizates under similar conditions. In order to analyse the processing behaviour, the green strength, mill shrinkage and Mooney viscosity of the compounds were determined. Finally, the polymer–filler interaction was studied using the Lorenz–Park and Kraus equations.