Natural Weathering and Sea Water Effects on the Durability of Glass Fiber Reinforced Vinylester: Fractographic Analysis

This paper presents a study of the effects of harsh outdoor weather and warm sea water on the tensile behavior of Glass-Fiber Reinforced Vinylester (GFRV) pipe materials destined for sea water handling and transportation. The effect of Dhahran’s outdoor weather for exposure periods ranging from 3 to 36 months revealed an improvement in tensile strength when compared with the as received GFRV sample. A significant increasing trend of tensile strength from 3 to 12 months was noted. This is attributed mainly to the post curing effects resulting in higher cross linking density. After 12 months of exposure the tensile strength showed a decreasing trend, but remaining still higher than the average tensile strength of as received (baseline) GFRV sample. Similar results of enhanced tensile strength were noted after immersion of GFRV pipes in warm Gulf sea water for 12 months. Fractographic analysis was performed on the tensile tested GFRV samples using optical microscope followed by scanning electron microscope (SEM). The characterization of the controlling failure mechanisms involved from fracture initiation to fracture propagation through the gage section of the specimen were predicted and were justified by correlating the optical and SEM pictures.     

成型工艺对玻璃纤维增强复合材料自然老化特性的影响分析

随着玻璃纤维增强复合材料在海洋工程中的应用越来越广泛,其自然老化特性也越来越受到研究者的重视.采用海水浸泡-阳光曝晒循环老化的方法来模拟海洋环境中复合材料的实际工作环境,分别评价手糊和真空成型两种玻璃纤维复合材料在海洋环境中的耐久性.通过对两种成型工艺复合材料老化前后的增重量变化和轴向拉伸强度、面内剪切强度等基本力学性能的分析,研究了不同成型工艺对玻璃纤维增强复合材料自然老化特性的影响规律.结果表明,增重量同时受到树脂含量、老化时间、温度和紫外线强度的影响;两种工艺成型的玻璃纤维增强复合材料力学性能在老化过程中表现出不同的衰减规律;干态和湿态材料力学性能的差异随老化时间的延长而增大.     

基于孔结构分析的多尺度聚丙烯纤维混凝土耐久性

为研究不同尺度纤维对混凝土耐久性的影响,借助压汞法技术测定多尺度聚丙烯纤维混凝土内部孔隙的孔径大小及分布情况,通过孔径分布、最可几孔径、平均孔径等孔隙特征参数的变化情况,探究多尺度聚丙烯纤维在抗渗试验、抗硫酸盐侵蚀循环试验、抗冻融试验中对混凝土耐久性的影响.研究结果表明:不同尺度聚丙烯纤维的掺入,均使得混凝土内部多害孔...     

玻纤增强尼龙6的断裂研究

通过对不同玻纤含量的玻纤增强尼龙复合材料(GFPA)的性能及断口形貌的研究,得出GFPA的宏观力学性能的变化可由断面形貌特征来定量表征。拉伸强度随拉伸断口断面平坦区面积与断面总面积之比AP/A0的变小而提高,Izod缺口冲击强度随GFPA的断面粗糙度参数RS的提高而线性提高。断面形貌的变化与玻纤在基体树脂中的应力集中作用及对裂纹扩展的阻碍作用有关。     

紫外-湿热老化对天然纤维增强复合材料力学性能的影响(英文)

用热压成型的方法制作了天然纤维(剑麻,红麻)增强酚醛复合材料,并测试和比较了紫外老化前后复合材料的力学性能。同时,也研究了表面处理对天然纤维增强复合材料力学性能的影响。结果表明,天然纤维复合材料的力学性能随着老化而不断下降。最后,引入了一个半经验模型来对天然纤维增强复合材料的服役行为进行了预测。     

长玻纤增强复合材料注塑成型构件强度分析

基于广义牛顿流体本构方程,采用ARD-RSC纤维取向模型,考虑纤维间相互作用,仿真预测长玻纤增强复合材料注塑构件的纤维取向分布;应用复合材料细观力学Eshelby夹杂理论和Mean Field均匀化方法,建立长玻纤增强复合材料均质化RVE模型;综合运用复合材料细观建模、离散RVE模型场、注塑成型和结构有限元分析技术,提出了长玻纤增强复合材料注塑构件强度分析方法。对推力杆注塑构件进行强度分析,显示仿真危险位置与实际破坏位置较为吻合。在此基础上对推力杆进行结构改进,结果表明杆体中间部分在拉伸载荷下的最大主应力降低了57.18%,在压缩载荷下的最大主应力降低了71.25%。     

玻璃纤维/玻璃微珠混杂增强聚氨酯泡沫铝压缩性能研究

通过实验制备了泡沫铝、聚氨酯泡沫铝(PUF泡沫铝)和增强PUF泡沫铝试件,并对它们的压缩性能进行了研究.结果表明,增强PUF泡沫铝尤其是混杂增强PUF泡沫铝的压缩性能优于纯泡沫铝和PUF泡沫铝,且当玻璃纤维含量为4.5％(质量分数)、玻璃微珠含量为1.5％(质量分数)时,混杂增强PUF泡沫铝复合材料的增强效果最好,可作为一种缓冲性能很好的防护材料.     

Water Absorption and Thickness Swelling Behavior of Polypropylene Reinforced with Hybrid Recycled Newspaper and Glass Fiber

This study aims to investigate the moisture absorption of recycled newspaper fiber and recycled newspaper-glass fiber hybrid reinforced polypropylene composites to study their suitability in outdoor applications. In this work composite materials were made from E-glass fiber (G), recycled newspaper (NP) and polypropylene (PP), by using internal mixing and hot-pressing molding. Long-term water absorption (WA) and thickness swelling (TS) kinetics of the composites was investigated with water immersion. It was found that the WA and TS increase with NP content in composite and water immersion time before an equilibrium condition was reached. Composites made from the NP show comparable results as those made of the hybrid fiber. The results suggest that the water absorption and thickness swelling composite decrease with increasing glass fiber contents in hybrid fiber composite. It is interesting to find that the WA and TS can be reduced significantly with incorporation of a coupling agent (maleated polypropylene) in the composite formulation. Further studies were conducted to model the water diffusion and thickness swelling of the composites. Diffusion coefficients and swelling rate parameters in the models were obtained by fitting the model predictions with the experimental data.     

纤维增强磷酸铝基复合材料的制备及性能研究

开展了纤维增强磷酸盐结合陶瓷基复合材料的研究,通过选择合适的增强纤维、结合剂及填充剂,采用叠层一热压固化—烧结的复合工艺,制备出隔热承力陶瓷基复合材料.料浆比例为10∶2.14∶3.00和孔径为1.5mm×1.5mm硅氧纤维布制备出的复合材料性能较好.密度对复合材料力学性能有很大影响,采用硅溶胶浸渍提高密度的方法,密度增加10.22％,抗弯强度增加了92.21％.     

高强玻纤增强ABS复合材料的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及玻璃纤维(GF)为原料,以苯乙烯-马来酸酐共聚物(SMA)和环氧树脂(E-poxyresin)作为界面相容剂,研究了界面相容剂对玻璃纤维增强ABS复合材料力学性能及界面粘接的影响。结果表明,加入SMA或环氧树脂,玻纤增强ABS复合材料的力学性能明显提高;SMA与环氧树脂复配有明显的协同效果,同时加入SMA和环氧树脂后的复合材料的性能更加优越,界面粘接性能得到很大的改善,在玻纤加入量为30%时,其拉伸强度、弯曲强度、冲击强度较未添加界面相容剂时分别提高了44%、29%、100%。     

玻璃/苎麻纤维混杂复合材料力学性能研究

混杂纤维增强复合材料由于可以综合利用各种纤维的优点,极大的提高了复合材料的性能,拓展了复合材料的适用范围。本文采用玻璃纤维和苎麻纤维混杂酚醛树脂制备复合材料,研究了复合材料混杂比和铺层顺序对混杂纤维复合材料力学性能的影响。从结果可以看出,玻璃纤维和苎麻纤维的不同比例对混杂复合材料的力学性能有着显著的影响,而采用玻璃纤维作为芯层的时候可以获得较好的拉伸性能,采用苎麻纤维作为芯层的时候可以获得较好的弯曲和剪切性能。     

Fiber Pretreatment and Its Effects on Wood Fiber Reinforced Polypropylene Composites

This study investigates the effect of pretreatment of fiber with NaOH and coupling with maleated polypropylene (MAPP) on the physical and mechanical properties of composites, based on radiata pine (Pinus Radiata) fiber, produced with a polypropylene matrix, using a twin-screw extruder followed by injection molding. Prior to reinforcement, the fiber was treated with NaOH. The effect of treatment was assessed using zeta potential, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Tensile testing, SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were carried out to assess the effect of modification on composite properties. An increase of 106% for strength and 302% for Young's modulus were obtained by using 60 wt% fiber and 2 wt% MAPP, compared to the unreinforced matrix. Fiber pretreatment with NaOH reduced strength but improved Young's modulus (370% compared to unreinforced matrix) of resulted composite.     

高强玻纤复合材料静态力学性能实验研究

利用电子万能试验机和静态应变仪测定了高强2号玻纤复合板的静态拉伸、静态压缩和剪切性能,得到了较为完整的静态力学性能数据,并对复合材料的拉伸破坏现象进行了分析.结果表明,高强玻纤复合材料具有良好的力学性能,是一种性价比较高的结构材料.     

注塑次数对玻纤增强阻燃PBT性能的影响

通过对五次注塑后的阻燃增强聚对苯二甲酸丁二醇酯(PBT)材料进行性能测试,研究注塑次数对材料的力学性能和热学性能的影响及其变化规律.当注塑次数为三次时,材料的玻纤长度仅为590μm,PBT树脂特性黏度仅为0.52,且随着注塑次数的增加进一步下降.对材料的力学性能、热学性能进行测试,结果发现经过两次注塑后,其缺口冲击强度...     

A Viscoelastic Analysis of the Creep Behaviour of a Chopped Strand Mat E-Glass Fibre Reinforced Vinylester Resin

The viscoelastic response of a chopped strand mat E-glass fibre reinforced vinylester resin has been studied over a wide range of applied stress levels. At low applied stress levels, the material exhibited a linear viscoelastic response well represented by Schapery's power law model with constant C and n terms. At higher stresses nonlinear behaviour was observed which apparently is caused by the multiplicity of complex local phenomena associated with and preceding damage development (plastic deformation of the matrix, interfacial slippage, fiber-matrix debonding). The limits of linear viscoelastic behaviour and of damage initiation – about 0.48% strain or 42 MPa – coincide for this material. However, for successful modelisation of uniaxial creep strain in the nonlinear range a modified power law is proposed which uses stress-dependent creep parameters C and n.     

玻璃纤维/大麻纤维增强聚丙烯混杂复合材料的力学性能和断裂特征(英文)

目前在土木工程,建筑,汽车等领域里使用的复合材料中,玻璃纤维是用量最大的增强材料。由于保护地球环境的呼声日趋高涨,天然纤维被期待着代替源于石油而且再利用困难的玻璃纤维,成为绿色复合材料的必要材料之一。本文通过注射成型工艺制作了玻璃短纤维,大麻短纤维以及混杂型纤维增强复合材料,并在拉伸实验中应用两种不同频率的声发射技术检测了拉伸断裂特性。实验发现,随着大麻纤维的加入和混杂复合材料绿色度的增加,复合材料的拉伸弹性模量随之线性增大,而拉伸强度基本保持不变。当大麻纤维的含量超过20wt%的时候,拉伸强度开始降低。在不同频率的声发射实验中,混杂型复合材料的声发射事件的产生都比单一纤维增强型复合材料要来的晚,也就是说,纤维的混杂有助于推迟微裂纹的产生。     

车用天然纤维增强复合材料吸声和热性能研究

以剑麻、苎麻和红麻三种天然纤维增强热固性基体复合材料为研究对象,通过树脂传递模塑(RTM)法和热压成型法制备复合材料,利用吸声测试系统测试了各材料的吸声系数,并依据准稳态法用自制导热系数测量装置测量了各材料的导热系数,进而对比分析了各材料吸声性能与热性能的差异。结果表明,天然纤维增强复合材料和结构的吸声性能及热性能优越,可有效地提高汽车的舒适性,具有较好的应用前景。