短纤维/橡胶发泡复合材料的微观结构及拉伸破坏机理

对锦纶短纤维增强的NR发泡材料的微观结构及拉伸破坏行为进行了研究，并分析了其破坏机理。采用未处理短纤维增强的NR发泡材料中短纤维成为泡孔的成核点，并大部分悬空在泡孔中，拉伸破坏时泡壁与短纤维结合处容易出现应力集中，成为裂纹的起始点，失效时短纤维大部分被抽出；预处理短纤维能与橡胶基体之间产生良好的粘合，从而处于橡胶基体中。其短纤维增强的NR发泡体拉伸产生的裂纹扩展时遇到纤维，纤维能起到承载应力、使应力转向、阻止裂纹扩展的作用，一定程度上改善了复合材料的拉伸强度等物理性。     

纤维增强聚合物发泡体的研究进展

纤维增强聚合物发泡体是一种新型的三相复合材料，纤维增强发泡体可以大大提高发泡体的弹性模量和压缩模量，提高材料的破坏强度，也显著地降低了材料的收缩率，因而可用于结构性材料。纤维增强发泡体中纤维特性，长径比，用量，与基体的粘合状态，泡孔的大小，形状，发泡密度等因素对发泡体系的性能均有影响，其中粘合是非常生要的。过长的纤维由于结构缠结对聚合物发泡体的增强并不理想。     

废旧轮胎短纤维的预处理及其在EPDM中的应用

研究了废纤维、改性废纤维、DN66 3种短纤维用量及其取向方向对短纤维/EPDM复合材料(SFRC)性能的影响。结果表明,随着短纤维用量的增加(用量在0～20.0份内),SFRC的硬度、100%定伸应力和撕裂强度逐渐增大,SFRC的拉伸强度和拉断伸长率呈下降趋势,从取向效果来看,L方向上的力学性能优于T方向;与添加未处理废纤维相比,添加预处理废纤维的SFRC的100%定伸应力、拉伸强度、拉断伸长率、撕裂强度均有不同程度的提高,与添加DN66的接近,部分性能甚至更好;SEM研究发现,未处理的废纤维在EP-DM基质中分散不均匀,与基体的界面粘合性能差,而经预处理后能有效地改善废纤维的分散性能和界面粘合性能。     

短纤维种类和用量对短纤维/EPDM复合材料物理性能的影响

研究未处理棉短纤维(SCF)、锦纶短纤维(DN66)和木质纤维素短纤维(E-140)用量对短纤维补强EPDM复合材料(SFRC)物理性能的影响。结果表明,在0~15份用量范围内,随着短纤维用量的增大,SFRC的硬度、100%定伸应力和撕裂强度呈增大趋势,拉伸强度和拉断伸长率呈下降趋势,其中填充DN66的SFRC 100%定伸应力和撕裂强度明显增大,拉伸强度下降较小,填充SCF的SFRC拉断伸长率下降较小。扫描电镜观察发现,未处理SCF在EP-DM基质中团聚严重,与基体的界面粘合性能较差。     

芳纶短纤维与三元乙丙橡胶界面粘合水平评估研究

研究不同表面预处理的芳纶短纤维填充的三元乙丙橡胶(EPDM)的拉伸应力-应变特性,提出采用相对界面滑脱能替代传统的拉伸强度指标来衡量短纤维与橡胶的界面粘合水平。结果表明:采用相对界面滑脱能能够更加科学地表征预处理芳纶短纤维与EPDM之间的界面粘合状况,相对界面滑脱能与预处理短纤维表面粘合状况和EP-DM胶料配方关系很大,与短纤维填充量和短纤维的取向程度关系不大。     

改性锦纶66短纤维/天然橡胶复合材料性能研究

对锦纶66（PA66）短纤维进行紫外光照射和浸渍液体橡胶物理改性,以及接枝化学改性共同处理,制备改性PA66短纤维/天然橡胶（NR）复合材料,并研究PA66短纤维改性方式对复合材料性能的影响。结果表明：与未改性的PA66短纤维/NR复合材料相比,改性PA66短纤维/NR复合材料的拉伸强度降低、撕裂强度提高;其中先接枝再紫外光照的PA66短纤维/NR复合材料的100%定伸应力变化不大,300%定伸应力提高,拉断伸长率变化不大;先紫外光照再接枝的PA66短纤维/NR复合材料的100%定伸应力和300%定伸应力明显提高,拉断伸长率明显降低。综合来看,经紫外光照4 min＋接枝乙烯基三甲氧基硅烷＋浸渍2 g液体橡胶处理的改性PA66短纤维/NR胶料的物理性能、粘合性能和尺寸稳定性最好。     

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。     

新型胶乳预处理尼龙短纤维体系的研究

采用特软羧基丁苯胶乳(苯乙烯质量分数为40％)和丙烯酸类胶乳(HST2073A型胶乳)对尼龙短纤维进行预处理，考察了预处理剂配方对短纤维橡胶复合材料(SFRC)性能的影响，得出了最适预处理液配方；把预处理短纤维应用于轮胎胎面胶中，通过性能测试比较了不同预处理短纤维-橡胶复合材料的力学性能；通过分析复合材料拉伸断面扫描电镜图，初步探讨了预处理在复合材料中的粘合机理。     

环状短纤维对橡胶增强效果的初步研究

提出了用环状短纤维对橡胶进行增强的想法,并对用该想法制得的复合材料与用普通短纤维制得的复合材料在力学性能上进行了比较分析。结果表明,环状短纤维的增强效果比普通短纤维好;用环状短纤维增强的橡胶试样在拉伸过程中表现出杨氏模量先小后大的特点,且Ｔ向与Ｌ向的拉伸强度相差不大     

尼龙和聚酯短纤维的长度对其与天然橡胶氯丁橡胶复合材料性能的影响

本就尼龙，聚酯短纤维的长度对尼龙－天然橡胶以及聚酯－氯丁橡胶复合材料的物理性能和溶胀性能的影响进行了理论研究。实验结果表明：这两种短纤维橡胶复合材料的撕裂强度，２０％定伸应力随短纤维长度增加而增大，抗溶胀能力增强，拉伸强度则在短纤维最佳长径比条件下最好。尼龙，聚酯短纤维经Ｄ法预处理后，其复合材料的各基性能均有较大提高。     

Studies of the Physico-Mechanical,Interfacial, and Degradation Properties of Jute Fabrics/Melamine Composites

Jute fabrics/melamine composites (20% fiber) were prepared by compression molding. Mechanical properties of the composites were evaluated. Mechanical properties of starch-treated jute/melamine composites, including tensile strength (31%), bending strength (29%), tensile modulus (23%), bending modulus (25%), impact strength (113%), and hardness (4%), inproved significantly over the untreated composite. Fracture surfaces of untreated and treated composites were studied by scanning electron microscopy (SEM) and supported poorer fiber matrix adhesion for the untreated composite than that of the treated composite. Water uptake and soil degradation tests of untreated and treated composites were also performed.     

Nanosilica as dry bonding system component and as reinforcement in short nylon‐6 fiber/natural rubber composite

Nanoscale silica was synthesized by acid hydrolysis of sodium silicate using dilute hydrochloric acid under controlled conditions. The synthesized silica was characterized by SEM, BET adsorption, and XRD. The particle size of silica was calculated to be 13 nm from the XRD results and the surface area was found to be 295 m²/g by BET method. This synthesized nanosilica was used in place of conventional silica in HRH (hexamethylenetetramine, resorcinol and silica) bonding system for natural rubber/Nylon‐6 short fiber composite. Nanosilica was also used as reinforcing filler in natural rubber/Nylon‐6 short fiber hybrid composite. Mechanical, thermal, and dynamic mechanical properties of the composites were evaluated. The introduction of the nanosilica in hybrid composites improved the tensile strength, modulus, and tear strength through improved interaction with the matrix which is facilitated by the higher surface area. Abrasion loss and hardness were also better for the nanosilica composites. Resilience and compression set were adversely affected. The hybrid composites showed anisotropy in mechanical properties. Peak rate of thermal decomposition decreased and temperature of initiation of thermal degradation increased with silica content, indicating improved thermal stability of the hybrid composites. The storage modulus and loss modulus showed two‐stage dependence on frequency at higher fiber loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies on mechanical properties of polyethylene–organic fiber composites. I. Nut shell flour

Composites were made from polyethylene and an organic fiber (pecan shell and peanut hull flour) using a compression-molding technique. Studies of variations in molding temperature (145–180°C), fiber concentration (0–40% by weight), and fiber mesh size (100, 200, and 325) were correlated to the mechanical properties of the composites (tensile strength, elongation, fracture energy, modulus, and impact strength). In untreated nut shell composites, tensile strength decreased steadily as the fiber concentration increased. This was due to poor bonding between the untreated fiber and polymer. Polyisocyanate was used as a coupling agent and its effect on mechanical properties of the composites was studied. Significant improvement in tensile strength was achieved with an isocyanate coupling agent, but it had no effect on modulus of the composites. Both untreated and isocyanate-treated composites had lower impact strength values; further composite matrix modifications would be necessary to maintain or improve impact strength.     

废尼龙短纤维/丙烯酸酯橡胶复合材料的性能研究

对废尼龙短纤维／丙烯酸酯橡胶复合材料中短纤维的分布状态和复合材料的性能进行了研究。结果表明,废尼龙短纤维能较好地分散在丙烯酸酯橡胶中;随短纤维用量的增大,复合材料的定伸应力和撕裂强度增大,抗溶胀性能提高,但拉伸强度减小     

Preparation,morphology and properties of natural rubber composites filled with untreated short jute fibres

Green composites were obtained by incorporation of short jute fibres in natural rubber matrix using a laboratory two-roll mill. The influence of untreated fibre content (1, 2.5, 5, 7.5 and 10 phr) on the mechanical properties, dynamic mechanical properties, swelling properties was examined. The behaviour of prepared green composites under cyclic compression was also investigated. Fibre dispersion in rubber matrix was studied by scanning electron microscopy. The highest tensile strength (21.1 MPa) and highest tear strength (39.9 N/mm) were found for composites containing 2.5 and 5 phr of short jute fibres, respectively. The results also suggested that increasing fibrous filler content resulted in increasing of tensile moduli 100, 200 and 300 % of elongation and hardness, and decreasing of rebound resilience and abrasion resistance of prepared jute/natural rubber composites. The cyclic compression test showed that increasing the amount of short jute fibres in the rubber matrix is related to increase of the energy dissipated in the composite. The incorporation of short jute fibres into the rubber matrix improves the stiffness of the composites, and it is related to the interaction between fibre surface and rubber matrix. The application of short fibres in higher amounts leads to formation of fibre agglomerates reducing the mobility of the rubber polymer chains. The mentioned agglomerates act as defects in rubber matrix, which caused decreasing of some properties, e.g. relative elongation at break.     

A comparative study of short nylon fiber—Natural rubber composites prepared from dry rubber and latex masterbatch

A novel method for the preparation of short nylon fiber–natural rubber composites was developed in which short fibers chopped to approximately 6 mm were incorporated in the latex stage and processed into sheet form. By this method, mixing cycle time was reduced without compromising the fiber dispersion. Fiber breakage during mixing was reduced. The new composites when compounded with a dry bonding system based on hexamethylenetetramine, resorcinol and hydrated silica (HRH) showed improved modulus, tensile strength and abrasion resistance compared to conventional composites. Tear strength, resilience, and compression set were similar to the conventional composites. SEM analysis indicated better interaction between matrix and fibers in the case of latex master batch. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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.     

Tensile and Impact Properties of Thermoplastic Natural Rubber Reinforced Short Glass Fiber and Empty Fruit Bunch Hybrid Composites

Thermoplastic natural rubber (TPNR) hybrid composite with short glass fiber (GF) and empty fruit bunch (EFB) fiber were prepared via the melt blending method using an internal mixer type Thermo Haake 600p. The TPNR were prepared from natural rubber (NR), liquid natural rubber (LNR) and polypropylene (PP) thermoplastic, with a ratio of 20:10:70. The hybrid composites were prepared at various ratios of GF/EFB with 20% volume fraction. Premixture was performed before the material was discharged into the machine. The study also focused on the effect of fiber (glass and EFB) treatment using silane and maleic anhydride grafted polypropylene (MAgPP) as a coupling agent. In general, composite that contains 10% EFB/10% glass fiber gave an optimum tensile and impact strength for treated and untreated hybrid composites. Tensile properties increase with addition of a coupling agent because of the existence of adherence as shown in the scanning electron microscopy (SEM) micrograph. Further addition of EFB exceeding 10% reduced the Young's modulus and impact strength. However, the hardness increases with the addition of EFB fiber for the untreated composite and decreases for the treated composite.     

Mechanical Properties of Benzoylated Oil Palm Empty Fruit Bunch Short Fiber Reinforced Poly(vinyl chloride) Composites

The influence of untreated and benzoylated oil palm empty fruit bunch (OPEFB) short fiber loading on the mechanical properties of the poly(vinyl chloride) (PVC) composite was studied. Benzoylated OPEFB was produced by mixing OPEFB with NaOH solution and agitating vigorously with benzoyl chloride. The PVC resin, various additives, and OPEFB were first dry blended using a laboratory mixer before being milled into sheets on a two-roll mill at 165°C and then hot pressed into composite samples at 180°C. The tensile and impact strength of untreated and benzoylated OPEFB composites decreased whereas the tensile modulus increased with increasing fiber loading from 0 to 40 phr. However, the benzoylated OPEFB was able to improve the tensile properties and impact strength of composites when compared to the untreated fiber. The enhancement of mechanical properties showed that the treatment improved the OPEFB fiber-PVC matrix interfacial adhesion. The improvement of adhesion was clarified by SEM micrographs, the increase of water resistance, and the reduction of glass transition temperature of the composites.     

Preparation and properties of successive alkali treated completely biodegradable short jute fiber reinforced PLA composites

The natural fiber reinforced biodegradable polymer composites were prepared with short jute fiber as reinforcement in PLA (Poly lactic acid) matrix. The short jute fiber is successively treated with NaOH at various concentrations (5%, 10%, and 15%) and H₂O₂. The composites were prepared with untreated and treated short jute fibers at different weight proportions (up to 25%) in PLA and investigated for mechanical properties. The results showed that the composite with successive alkali treated jute fiber at 10% NaOH and H₂O₂ with 20% fiber loading has shown 18% higher flexural strength than neat PLA and untreated jute/PLA composite. The flexural modulus of the composite at 25% fiber loading was 125% and 110% higher than that of composites with untreated fibers and neat PLA, respectively. The impact strength of composite with untreated fibers at higher fiber weight fraction was 23% high as compared to neat PLA and 26% high compared to composite with treated fibers. The water absorption was more for untreated jute/PLA composite at 25% fiber loading than all other composites. The composite with untreated fibers has high thermal degradation compared with treated fibers but lower than that of pure PLA matrix. The enzymatic environment has increased the rate of degradation of composites as compared to soil burial. Surface morphology of biodegraded surfaces of the composites were studied using SEM method. POLYM. COMPOS., 37:2160–2170, 2016. © 2015 Society of Plastics Engineers