纤维与颗粒混杂增强聚氨酯硬泡塑料的制备及显微形貌

采用尼龙66纤维及SiO2颗粒粉末作为增强剂制备了混杂增强聚氨酯硬泡塑料,这种混杂增强硬泡塑料的力学性能包括拉伸强度．压缩强度,冲击强度都有明显提高。研究表明,为达到增强效果增强剂必须以偶联剂预处理。当尼龙66纤维的含量为7％,SiO2的含量为20％时所得聚氨酯泡沫塑料的力学性能增强最佳。SEM现察表明该硬泡塑料胞体平均大小为60um左右。从拉伸断口形貌可看出纤维受力痕迹明显．表明纤维本身的拉伸强度对于硬泡塑料的力学性能增强起了重要作用。     

纳米SiO2/纤维素复合材料的非均相制备及其性能

采用硅酸四乙酯(TEOS)作为无机前聚物,纤维素为有机组分,利用溶胶-凝胶法在非均相乙醇溶液中制备了纳米SiO₂/纤维素复合材料。通过傅里叶红外光谱(FTIR)、透射电镜(TEM)和热重分析(TGA)对复合材料的形貌、结构以及热稳定性进行表征。讨论了SiO₂含量对材料力学性能的影响。研究了主要因素碱催化剂氨水对纤维素与SiO₂复合效果的影响。结果表明,纳米复合材料的弹性模量、拉伸强度随SiO₂含量的增加先增加后减少,质量分数分别为3.1％、10.6％时弹性模量、拉伸强度达到最大。氨水加入量为3.70×10-4 mol/L时,纤维素与SiO₂的复合效果最佳。非均相制备的纳米SiO₂/纤维素复合材料同样也明显提高了纤维素材料的疏水性、热稳定性和力学性能。     

掺杂二氧化硅干凝胶孔结构的分形特性

利用溶胶-凝胶酸碱二步催化法和常压干燥法制备了掺有不同含量TiO₂粉末、 自制SiO₂干凝胶纳米粉末和微玻璃纤维的SiO₂干凝胶。采用氮气吸附-脱附实验,由经典FHH方程计算得到各掺杂SiO₂干凝胶的表面分形维数。比较研究了不同添加物对SiO₂干凝胶密度、 孔结构和比表面积等的影响, 并根据de Boer理论判断了孔隙的形状。结果表明, 添加物不仅能够增强SiO₂干凝胶的强度, 抑制湿凝胶干燥过程中的收缩, 而且能改变其孔隙结构和颗粒堆积方式。SiO₂纳米颗粒能够降低SiO₂干凝胶的比表面积, 且使其孔径分布逐渐变宽;而TiO₂粉末和短切纤维, 能够提高SiO₂干凝胶的比表面积, 最终获得的改性SiO₂干凝胶最高比表面积可达1064.96m2/g。各个样品的表面分形维数均在2.4~2.5之间。     

纳米SiO2/尼龙66复合材料的力学性能和热性能

采用熔融共混的方法在双螺杆挤出机上制备出纳米SiO₂/尼龙66复合材料,并对其力学性能和热性能进行了研究。结果表明：复合材料的拉伸强度和弹性模量随纳米SiO₂含量的增加而提高。当SiO₂质量分数为3％时,复合材料的拉伸强度达到最大,增幅为11.2％;当SiO₂质量分数为5％时,弹性模量达到最大, 增幅为30.1％。复合材料的储能模量和玻璃化转变温度较纯尼龙66也有明显提高。差示扫描量热法（DSC）分析显示,纳米SiO₂的加入一方面阻碍了尼龙66的结晶过程,降低了材料的结晶温度;另一方面它又能作为形核剂,增加尼龙66的形核位置,提高形核率。     

表面修饰纳米SiO2增强增韧聚氯乙烯

用过量的2 , 4-甲苯二异氰酸酯(TDI)对纳米SiO₂表面进行修饰合成含—NCO 的功能化SiO_2,再用丙烯酸羟丙酯(HPA)对其表面进行修饰合成出HPA修饰纳米SiO₂(SiO₂-HPA)。用共混法制备了SiO₂-HPA/PVC纳米复合材料,研究了不同 SiO₂含量及不同界面特性时复合材料的力学性能。结果表明: SiO₂-HPA/PVC复合材料的力学性能和加工性能等方面均优于未修饰的样品。在纳米SiO₂质量分数为0%～5%时,SiO₂-HPA/PVC的拉伸强度和冲击强度随着填充量的增加呈先上升后下降的趋势并在3%～4%达到最大值。表面修饰纳米SiO₂与PVC基体之间具有很强的界面结合作用,其相容性得到大大改善,填充表面修饰纳米SiO₂达到了增强增韧双重效果。此外,对纳米粒子增强增韧机制进行了深入的探讨。     

弹性体修饰纳米SiO2粒子改性PBT

选用乙烯-丙烯酸酯-甲基丙烯酸缩水甘油酯(E-MA-GMA)三元共聚物对纳米SiO₂表面进行修饰包覆改性,考察改性后纳米SiO₂在聚对苯二甲酸丁二醇酯(PBT)基体中的分散情况及对PBT复合材料力学性能的影响。FTIR、TEM、SEM结果表明,E-MA-GMA的环氧基团与纳米SiO₂的—OH 基团发生反应,破坏了SiO₂的链状团聚结构,降低了纳米粒子间氢键等作用力。质量分数为10%～20% E-MA-GMA 改性的纳米SiO₂在PBT基体中的分散性及其与基体的相容性均得到明显改善,从而提高了PBT基复合材料的弯曲和拉伸性能。与纯PBT相比,SiO₂/PBT复合材料的拉伸强度提高了9%,而弯曲强度和模量分别提高了14%和20%。     

纳米SiO2表面接枝聚合改性及其聚丙烯基复合材料的力学性能

分别用苯乙烯和丙烯酸乙酯对纳米SiO₂进行辐照接枝聚合改性,通过两步熔融共混工艺与聚丙烯(PP)共混制备了SiO₂/PP复合材料。研究了SiO₂添加量和表面接枝不同聚合物的SiO₂对复合材料力学性能的影响。结果表明,接枝改性的SiO₂对PP有较好的增强增韧效果;拉伸断面观察显示复合材料韧性的提高主要由基体剪切屈服所致。对断面上个别较大团聚体分析发现,经辐照接枝聚合改性的纳米粒子团聚体的结构变得更加紧凑、结实,且随粒子表面聚合物的性质不同,团聚体与基体树脂的界面粘结也随之不同,导致其拉伸破坏形状有所差异,但与基体树脂的界面粘结都得到较好的改善。     

碳纤维-玻璃纤维层内混杂单向增强环氧树脂复合材料拉伸性能

采用不同混杂比的碳纤维-玻璃纤维层内经向混编单轴向织物制备了混杂纤维增强环氧树脂复合材料, 研究了不同混杂结构和不同混杂比的碳纤维-玻璃纤维/环氧树脂复合材料拉伸性能的变化及破坏形式。0°拉伸结果表明:同种混杂织物的不同混杂结构中, 碳纤维相对集中的完全对齐结构强度最高, 不同混杂比织物的完全对齐结构强度相当;碳纤维-玻璃纤维/环氧树脂复合材料的模量遵循混合定律。90°拉伸结果表明:纤维与树脂间的界面结合强度为碳纤维/树脂>玻璃纤维/树脂, 碳纤维-玻璃纤维/环氧树脂复合材料的强度、模量与材料厚度方向上界面的不同形式(单一或交替界面、碳纤维或玻璃纤维的分布位置等)有关, 与碳纤维的含量基本无关。      

Cf-ZrW2O8/9621复合材料制备及碳纤维和ZrW2O8含量对其热膨胀的影响

热膨胀是影响复合材料性能和使用寿命的主要因素之一。为研究具有低/负热膨胀的复合材料,本文以碳纤维粉、ZrW₂O₈颗粒和环氧树脂为原料,采用模压法制备了C_f-ZrW₂O₈/9621环氧树脂基复合材料,研究了碳纤维粉和ZrW₂O₈颗粒含量对复合材料热膨胀行为的影响规律,并分析了不同温度区间内C_f-ZrW₂O₈/9621环氧树脂基复合材料热膨胀的变化规律。研究结果表明:在30~200 ℃范围内,当ZrW₂O₈颗粒含量不变时,随着碳纤维粉含量的增加复合材料的平均热膨胀系数逐渐降低,其中碳纤维粉含量增加到12%时,复合材料的平均热膨胀系数最低,为29.9×10^{-6/℃,降低了约60%;当碳纤维粉含量不变时,ZrW₂O₈颗粒含量逐渐增加到12%时,复合材料的平均热膨胀系数呈现先减小后增加的趋势,当ZrW₂O₈颗粒含量为9%时,复合材料的热膨胀系数最低,为40.8×10-6}/℃,降低了约28%。在30~200 ℃范围内,C_f-ZrW₂O₈/9621复合材料在热膨胀过程中,温度升高后试样长度的变化量dL与试样原始长度L₀的比值出现增加、减小和增加3个阶段。碳纤维粉和ZrW₂O₈颗粒均能够降低复合材料的热膨胀系数,但碳纤维粉降低复合材料热膨胀的效果比ZrW₂O₈颗粒更好些。     

C/SiO2同轴复合纤维的制备及性能研究

以SiO₂溶胶为壳层,聚丙烯腈(PAN)溶液为芯层,采用同轴静电纺丝法制备了PAN/SiO₂同轴复合纤维. 经过预氧化,炭化处理,得到1μm的C/SiO₂同轴复合纤维. 采用傅立叶红外分析仪(FTIR)、X射线衍射分析仪(XRD)、扫描电镜(SEM)表征了同轴纤维结构和纤维截面形貌,表明利用同轴静电纺丝技术在碳纤维上制备了厚度约20nm的SiO₂涂层. 采用网络分析仪研究了同轴复合纤维的吸波性能,纤维质量分数为20％时,同轴复合纤维介电常数实部和虚部均比未涂层碳纤维低. 根据电磁参数采用RAMCAD软件计算了3mm厚材料反射率,在2～18GHz频率范围内,材料的最低反射率达到-17dB,对应的频率为12GHz,<-10dB的带宽为3.3GHz. 热重(DTA-TG)分析表明同轴复合纤维的抗氧化性能较未涂层碳纤维有所提高.     

Design of an impact resistant glass fibre/epoxy composites using short silk fibres

The prevailing utilisation of light and strong structural materials has led to an increasing demand to engineering industries on developing different types of advanced composites. Thus, the development of simple and low cost woven glass fibre composites with an improvement on their tensile and impact properties is suggested. In this paper, the hybridization of a glass fibre reinforced composite is achieved by using low cost short silk fibres as a medium to enhance its cross-ply strength. The comparison on the tensile and impact properties of the composite reinforced by the short silk fibre (with the content from 0.3 to 0.6 wt%) with a pristine glass fibre composite sample was conducted. Fracture surfaces were analysed by using scanning electron microscopy (SEM). Experimental results indicated that the maximum Young’s modulus and ductility index (DI) of a silk reinforced composite increased by 50% and 75%, respectively as compared with the pristine one. Furthermore, the visual examination on drop-weight test samples proved that the impact resistance of the silk reinforced composite was better than that of the pristine sample as well. According to the results obtained, it was found that the addition of 0.4 wt% short silk fibre into glass fibre composite was shown to be the advisable reinforcement content to achieve better tensile and impact strengths.     

连续长玻璃纤维/聚氨酯复合材料的制备与力学性能

以三羟基聚醚多元醇（PPG）、二苯基甲烷二异氰酸酯（MDI）作为软段和硬段,玻璃纤维（GF）为增强体,采用预聚体法制备自交联型GF/聚氨酯（PU）复合材料。借助旋转式黏度计、DMA、SEM、XRD和万能力学试验机等分析检测手段,研究了PU预聚体聚合温度、适用期、物相及GF含量等因素对GF/PU复合材料力学性能的影响。结果表明:PU预聚体聚合温度为50℃,GF含量为55wt%时,GF/PU复合材料综合性能最优,拉伸强度、弯曲强度和冲击韧性分别为794 MPa、846 MPa和228 kJ/m2,动态力学性能损耗因子（tanδ）峰值为0.59。      

气相、沉淀、稻壳SiO2/聚氨酯复合材料的力学性能和吸水性比较

比较了气相、沉淀和稻壳SiO2的物理性质,并利用上述3种SiO2与聚氨酯(PU)复合,考察了SiO2含量(1wt%,3wt%,5wt%)和种类对SiO2/PU复合材料的拉伸性能和吸水性的影响。结果表明:3种SiO2均能够提高SiO2/PU复合材料的力学性质,复合材料的拉伸强度、模量和断裂伸长率均随SiO2含量增加而增加。当SiO2含量相同时,拉伸强度和断裂伸长率的变化顺序为:气相SiO2/PU>沉淀SiO2/PU>稻壳SiO2/PU,拉伸模量的变化顺序为:气相SiO2/PU>稻壳SiO2/PU>沉淀SiO2/PU.对于同一种SiO2/PU复合材料,吸水性随SiO2含量和温度增加而增加,含量相同时,3种SiO2/PU复合材料的吸水性由低到高的顺序是:稻壳SiO2/PU<沉淀SiO2/PU<气相SiO2/PU。     

Date palm wood flour/glass fibre reinforced hybrid composites of recycled polypropylene: Mechanical and thermal properties

Recycled polypropylene (RPP) based hybrid composites of date palm wood flour/glass fibre were prepared by different weight ratios of the two reinforcements. Mixing process was carried out in an extruder and samples were prepared by injection molding machine. Recycled PP properties were improved by reinforcing it by wood flour. The tensile strength and Young’s modulus of wood flour reinforced RPP increased further by adding glass fibre. Glass fibre reinforced composites showed higher hardness than other composites. Morphological studies indicated that glass fiber has good adhesion with recycled PP supporting the improvement of the mechanical properties of hybrid composites with glass fiber addition. Addition of as little 5 wt% glass fibre to wood flour reinforced RPP increases the tensile strength by about 18% relative to the wood flour reinforcement alone. An increase in wood particle content in the PP resulted in a decrease in the degree of crystallinity of the polymer. The tensile strength of the composites increased with an increase in the percentage of crystallinity when adding the glass fibre. The improvement in the mechanical properties with the increase in crystallinity percentage (and with the decrease of the lamellar thicknesses) can be attributed to the constrained region between the lamellae because the agglomeration is absent in this case.     

Carbon fibre reinforced glass matrix composite tension and flexure properties

Carbon fibre reinforced borosilicate glass matrix composites have been fabricated to determine their mechanical properties in tension and flexure. Composite tensile stress-strain properties, including elastic modulus, proportional limit and ultimate tensile strength, have been measured as a function of fibre content. Composite tensile properties were also obtained at temperatures of up to 625° C through the testing of 0/90 cross-plied specimens. Composite short-beam shear strength was found to depend on specimen orientation and also on the composition of the glass matrix. This compositional dependence was associated with an independent measurement of the fibre-matrix interfacial shear strength and was related to the degree of fibre-matrix reaction taking place during composite fabrication.     

The potential of harakeke fibre as reinforcement in polymer matrix composites including modelling of long harakeke fibre composite strength

Mechanical properties of aligned long harakeke fibre reinforced epoxy with different fibre contents were evaluated. Addition of fibre was found to enhance tensile properties of epoxy; tensile strength and Young’s modulus increased with increasing content of harakeke fibre up to 223 MPa at a fibre content of 55 wt% and 17 GPa at a fibre content of 63 wt%, respectively. The flexural strength and flexural modulus increased to a maximum of 223 MPa and 14 GPa, respectively, as the fibre content increased up to 49 wt% with no further increase with increased fibre content. The Rule of Mixtures based model for estimating tensile strength of aligned long fibre composites was also developed assuming composite failure occurred as a consequence of the fracture of the lowest failure strain fibres taking account porosity of composites. The model was shown to have good accuracy for predicting the strength of aligned long natural fibre composites.     

Properties of glass fibre cement — the effect of fibre length and content

The properties of glass fibre reinforced cement composites (grc) containing alkali-resistant fibres of lengths 10 to 40 mm and volume fractions 2 to 8% have been studied. At 28 days the optimum properties of the composite were achieved with 6 vol % fibre addition. These were 4 to 5 times the bending strength, 3 to 4 times the tensile strength and 15 to 20 times the impact strength of the unreinforced cement paste. Further increase in the fibre content increases the porosity of the composite resulting in the lowering of bending and tensile strengths. The stress and strain of the composite at matrix cracking increased with increasing fibre contents. No significant improvements in the modulus of the composite were observed over the range of fibre additions investigated. The trends in the properties of grc as affected by the variations in volume fraction and length of the fibre, and environmental conditions of curing of the composites, are qualitatively related to the degree of cement hydration, changes in porosity of the composites and fibre/matrix interfacial effects. The properties of grc change with time, (strengths tend to decrease) and long term studies are in progress.     

Influence of nanosize clay platelets on the mechanical properties of glass fiber reinforced polyester composites

Glass fiber reinforced polyester composite and hybrid nanoclay-fiber reinforced composites were prepared by hand lay-up process. The mechanical behavior of these materials and the changes as a result of the incorporation of both nanosize clay and glass fibers were investigated. Composites were prepared with a glass fibre content of 25 vol%. The proportion of the nanosize clay platelets was varied from 0.5 to 2.5 vol%. Hybrid clay-fiber reinforced polyester composite posses better tensile, flexural, impact, and barrier properties. Hybrid clay-fiber reinforced polyester composites also posses better shear strength, storage modulus, and glass transition temperature. The optimum properties were found to be with the hybrid laminates containing 1.5 vol% nanosize clay.     

Experimental and theoretical studies on the properties of injection moulded glass fibre reinforced mixed plastics composites

Recycled mixed post-consumer and post-industrial plastic wastes consisting of HDPE, LDPE and PP were injection moulded with short glass fibre (10–30% by weight) to produce a new generation composite materials. Intensive experimental studies were then performed to characterise the tensile, compression and flexural properties of glass fibre reinforced mixed plastics composites. With the addition of 30 wt.% of glass fibre, the strength properties and elastic modulus increased by as much as 141% and 357%, respectively. The best improvement is seen in the flexural properties due to the better orientation of the glass fibres in the longitudinal direction at the outer layers. The randomness and length of the glass fibre were accounted to modify the existing rule of mixture and fibre model analysis to reliably predict the elastic and strength properties of glass fibre reinforced mixed plastics composites.     

The effect of reprocessing on the mechanical properties of polypropylene reinforced with wood pulp,flax or glass fibre

Composites of polypropylene, substitutable for a given application and reinforced with: Medium Density Fibreboard fibre (MDF) (40 wt%); flax (30 wt%); and glass fibre (20 wt%), were evaluated after 6 injection moulding and extrusion reprocessing cycles. Of the range of tensile, flexural and impact properties examined, MDF composites showed the best mean property retention after reprocessing (87%) compared to flax (72%) and glass (59%). After 1 reprocessing cycle the glass composite had higher tensile strength (56.2 MPa) compared to the MDF composite (44.4) but after 6 cycles the MDF was stronger (35.0 compared to 29.6 MPa for the glass composite). Property reductions were attributed to reduced fibre length. MDF fibres showed the lowest reduction in fibre length between 1 and 6 cycles (39%), compared to glass (51%) and flax (62%). Flax fibres showed greater increases in damage (cell wall dislocations) with reprocessing than was shown by MDF fibres.