碱处理对酚醛树脂/剑麻纤维复合材料性能的影响

用碱处理方法对剑麻纤维(SF)进行表面改性,再与酚醛树脂(PF)混合、塑炼、模压成型,制备了PF／SF复合材料,对其冲击强度、弯曲强度、耐磨性、吸水性及热性能进行测试,借助偏光显微镜和扫描电子显微镜观察、分析了复合材料的形态结构。结果表明,经碱处理的SF提高了PF／SF复合材料的综合性能,其原因与界面作用得到加强有关。     

表面处理方法对剑麻纤维/酚醛树脂复合材料性能的影响

分别采用碱、硅烷偶联剂、阻燃剂对剑麻纤维(SF)进行表面处理,采用模压成型工艺制备了SF/酚醛树脂(PF)复合材料。研究了SF表面处理方法对SF/PF复合材料的摩擦磨损性能、力学性能、吸水性的影响,借助扫描电镜观察了复合材料磨损面的形貌。结果表明:SF经阻燃剂处理后,SF/PF复合材料的磨损体积为0.00053cm3,比未处理的SF/PF复合材料减少了77.2%;SF经硅烷偶联剂处理后,SF/PF复合材料的冲击强度、弯曲强度分别比未处理的SF/PF复合材料提高18.7%、15.4%,且耐水性也有一定改善。     

表面处理对剑麻纤维表面状况及热性能的影响

采用含氟防水剂和硅烷偶联剂对剑麻纤维进行表面处理。通过扫描电镜(SEM)、热重分析(TG)、红外光谱(IR)、X-射线光电子能谱(XPS)和表面张力试验等手段表征了处理前后的剑麻纤维表面状况和热性能的变化。结果表明．防水剂与剑麻纤维的作用主要以化学作用为主,并使得剑麻纤维束的结合力减弱,但是防水剂能有效地降低剑麻纤维的吸水性。KH-550与剑麻纤维的作用主要以物理作用为主,并使得剑麻纤维束结合得更紧。     

聚丙烯/碱处理剑麻纤维复合材料的结构与性能

用注射成型的方法制备了聚丙烯(PP)／碱处理剑麻纤维(SF)复合材料,研究了材料的热性能、晶态结构、微观结构和力学性能。结果表明,碱处理SF对复合材料的热稳定性影响较小,但提高了PP相的结晶速率和结晶度,诱导了卢晶型PP的生成,提高了复合材料的弹性模量,对PP有显著的增韧效果;但弱的界面键合降低了复合材料的拉伸强度。     

玻璃纤维布/苎麻纤维布混杂增强不饱和聚酯树脂的研究

采用玻璃纤维布与苎麻纤维布混杂增强不饱和聚酯(UP)树脂制备复合材料,研究玻纤布与苎麻布的相对比例及偶联剂处理对复合材料力学性能的影响,研究了不同复合材料的吸水性并与玻璃纤维复合材料和苎麻纤维复合材料二者进行了比较。结果表明,混杂纤维增强复合材料的拉伸强度、拉伸模量随混杂纤维中苎麻布含量的增加而下降,弯曲强度及弯曲模量在混杂纤维中苎麻布与玻纤布的比例为10∶20和15∶15时分别达到最大值188.09 MPa和1.56 GPa;所有偶联剂处理均可明显改善复合材料的拉伸模量及弯曲模量,硅烷类偶联剂的效果更佳,NDZ401可使复合材料的拉伸强度得到最大幅度(37.66%)的提高,而KH570及NDZ401对改善弯曲强度效果最佳;复合材料吸水后,厚度变化率大于宽度变化率,温度升高,复合材料吸水后尺寸变化率及吸水率均增大,混杂纤维复合材料的吸水率与玻纤布复合材料的吸水率相近,远低于苎麻布复合材料的吸水率。     

剑麻纤维不饱和聚酯环境材料

剑麻纤维／不饱和聚酯环境材料可以使用玻璃钢模具有常温低压下模压成型,且在生产过程中不污染环境,其制品强度高,握螺钉性能好,耐水性优良,并且造价低廉。     

剑麻纤维/聚合物复合材料研究进展

主要概述了剑麻纤维(SF)的表面处理方法、SF增强热塑性聚合物及热固性聚合物复合材料的结构及性能,指出了SF增强聚合物复合材料今后的研究与发展方向。     

不饱和聚酯/剑麻纤维复合材料性能的研究

采用乙酰化、氰乙基化、KMnO4、甲苯二异氰酸酯(TDI)以及硅烷偶联剂等不同化学方法对剑麻纤维(SF)进行表面处理，然后将SF细化，与不饱和聚酯共混，通过模压成型制成不饱和聚酯／剑麻纤维复合材料，对复合材料的冲击强度、弯曲强度、热失重温度(Td)、电性能、吸水性能与SF处理方法的关系进行了研究，同时，考察了SF用量对复合材料各性能的影响。结果表明：SF处理方法对复合材料的电性能、热性能和吸水性影响不大；SF用量对复合材料的力学性能、吸水性影响较大，对电性能影响较小；当SF用量为10％，采用硅烷偶联剂和TDI处理SF时，复合材料强度较高、耐磨性好、综合性能较好。     

纤维表面处理对短纤维/丁腈橡胶复合材料性能的影响

使用经间苯二酚-甲醛-胶乳(RFL)体系处理及未处理的短切芳纶纤维(AF)和尼龙纤维(NF)分别与丁腈橡胶(NBR)制备复合材料,研究了纤维种类和表面处理对复合材料的性能,尤其是力学性能和耐磨性的影响。结果表明,与NF/NBR复合材料相比,AF/NBR复合材料的硬度和模量较高,但拉伸强度和扯断伸长率较低,这是由于AF与橡胶间较弱的相互作用及较大的模量差所导致的。对纤维进行RFL处理后,AF/NBR和NF/NBR复合材料的扯断伸长率分别提高297%和28%,前者的拉伸强度提高了30%,这可归因于RFL层对纤维-橡胶界面作用的提升。此外,AF/NBR复合材料的耐磨性较NF/NBR复合材料更好;RFL处理可通过改善NF与NBR的界面作用力提高复合材料的耐磨性,但降低AF/NBR复合材料的耐磨性,这是由于RFL的引入使后者硬度下降所致。     

剑麻纤维的改性方法对其形态结构和力学性能的影响

通过碱处理和烷基化处理改性剑麻纤维,研究剑麻纤维改性前后表面形态和力学性能的变化,并分析不同改性方法对加工过程中纤维断裂方式的影响.结果表明:碱处理和烷基化处理刻蚀了剑麻纤维表面;烷基化处理使纤维的断裂方式发生改变,导致纤维原纤化;剑麻纤维经改性处理后,拉伸强度分别提高9%和21%,断裂伸长率分别提高63.4%和122.2%.     

纤维表面处理对复合材料力学性能的影响

本文研究了碳纤维表面处理方法对纤维-基体界面剪切强度的影响．研究结果表明，相对于未进行表面处詈的碳纤维-所采用的胺基化处理和偶联剂处理两种表面处理方法都能够提高碳纤维界面的剪切强度，从而提高复合材料整体的抗拉强度和弹性模量。并且偶联剂处理方法具有更好的工艺性．     

黄麻纤维增强不饱和聚酯树脂初步研究

以油酸为偶联剂,将氢氧化钠-油酸处理后的黄麻纤维布作为填充材料制备了不饱和聚酯复合材料,并对氢氧化钠处理黄麻纤维的适宜浓度、复合材料的拉伸强度、冲击强度、吸水率进行了研究测试。结果表明:氢氧化钠的适宜浓度为20%,黄麻纤维增强不饱和聚酯树脂的冲击强度及拉伸强度最大值分别为12.75 kJ/m2和33.05 MPa,复合材料的最大吸水率为4.07%。经油酸处理的黄麻纤维可有效提高不饱和聚酯复合材料的性能。     

Effect of fiber treatment on the mechanical properties of LDPE-henequen cellulosic fiber composites

The degree of mechanical reinforcement that could be obtained by the introduction of henequen cellulosic fibers in a low-density polyethylene, LDPE, matrix was assessed experimentally. Composite materials of LDPE-henequen cellulosic fibers were prepared by mechanical mixing. The concentration of randomly oriented fibers in the composite ranged between 0 and 30% by volume. The tensile strength of these composite materials increased up to 50% compared to that of LDPE. There is also a noticeable increase in Young's modulus for the composite materials that compares favorably with that of LDPE. As expected, the addition of the fibers decreases the ultimate strain values for the composite materials. The thermal behavior of the LDPE-henequen cellulosic fibers materials, studied by differential scanning calorimetry, DSC, showed that the presence of the fibers does not affect the thermal behavior of the LDPE matrix; thus, the interaction between fiber and matrix is probably not very intimate. Preimpregnation of the cellulosic fibers in a LDPE-xylene solution and the use of a silane coupling agent results in a small increment in the mechanical properties of the composites, which is attributed to an improvement in the interface between the fibers and the matrix. The shear properties of the composites also increased with increasing fiber content and fiber surface treatment. It was also noted that the fiber surface treatment improves fiber dispersion in the matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 197–207, 1997     

Mechanical properties of woodflour unsaturated polyester composites

Agrowastes and woodflour are a potential and attractive alternative of cheap reinforcement for brittle polymeric materials because they can reduce costs and, at the same time, improve certain properties. On the other hand, their high moisture sorption and low microbial resistance are disadvantages that need to be considered and, as far as possible, corrected. Polyester resins are widely used throughout the world, and can be processed with reinforcing agents very easily. In this work, the effect of the addition of chemically modified woodflour on the final properties of unsaturated polyester composites was studied. The filler was treated with an alkaline solution to increase its interfacial area and then modified with maleic anhydride (MAN) under severe reaction conditions (140°C, 24 h). No improvement in the mechanical behavior of polyester–woodflour composites was found when particles were only alkali treated, while the composites prepared with MAN-treated woodflour offered better performance under compressive loads. Simple mechanical models used to fit the experimental flexural behavior indicated that a good compatibility between filler and matrix was obtained regardless of the kind (treated or untreated) of reinforcement used. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2121–2131, 1998     

Effect of fiber surface treatment on the properties of biocomposites from nonwoven industrial hemp fiber mats and unsaturated polyester resin

Biocomposites were made with nonwoven hemp mats and unsaturated polyester resin (UPE). The hemp fiber volume fraction was optimized by mechanical testing. The effect of four surface treatments of industrial hemp fibers on mechanical and thermal properties of biocomposites was studied. The treatments done were alkali treatment, silane treatment, UPE (matrix) treatment, and acrylonitrile treatment. Bending strength, modulus of elasticity, tensile strength, tensile modulus, impact strength, storage modulus, loss modulus, and tan δ were evaluated and compared for all composites. The mechanical as well as thermal properties of the biocomposites improved after surface treatments. The properties of the above biocomposites were also compared with E‐glass–mat composite. To achieve balance in properties, a hybrid composite of industrial hemp and glass fibers was made. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1055–1068, 2006     

Interfacial microstructure and properties of carbon fiber-reinforced unsaturated polyester composites modified with carbon nanotubes

To improve the interfacial properties in carbon fiber (CF)-reinforced unsaturated polyester (UP) composites, we directly introduced functionalized carbon nanotubes dispersed in the fiber sizing onto the fiber surface. For comparing the influence of polymer type on sizing effect, two different polymers (UP MR13006 and water-soluble epoxy (EP)) were used to prepare sizing agent. Morphology and surface energy of CFs were examined by scanning electron microscopy and dynamic contact angle analysis test. Tensile strength was investigated in accordance with ASTM standards. Mechanical properties of the composites were investigated by interlaminar shear strength (ILSS) and impact toughness. Test results indicate that TS, ILSS, and impact toughness were enhanced simultaneously. For UP matrix, the sizing agent containing UP has better reinforcing and toughening effect than the sizing agent containing water-soluble EP.     

Thermal and mechanical properties of LDPE/sisal fiber composites compatibilized with functionalized paraffin waxes

The effect of maleic anhydride‐grafted hard paraffin wax (MA‐g‐wax) and oxidized hard paraffin wax (OxWax), as possible compatibilizers, on the morphology, thermal and mechanical properties of LDPE/sisal fiber composites were examined. The differential scanning calorimetry (DSC) results show that sisal alone did not change the crystallization behavior of LDPE, while the two waxes influenced the crystallization behavior of LDPE in different ways, whether mixed with LDPE alone or in the presence of sisal. The thermal properties seem to be influenced by the fact that the waxes preferably crystallize around the short sisal fibers, and by the fact that the two waxes have different compatibilities with LDPE. The TGA results show an increase in the thermal stability of the blends in the presence of the two waxes, with LDPE/OxWax showing a more significant improvement. The presence of wax, however, reduced the thermal stability of the LDPE/sisal/wax composites. The presence of OxWax and MA‐g‐wax similarly influenced the tensile properties of the composites. Both waxes similarly improved the modulus of the compatibilized composites, but in both cases the tensile strengths were worse, probably because of a fairly weak interaction between LDPE and the respective waxes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of poly(vinyl chloride)/virgin and treated sisal fiber composites

Mechanical property changes, thermal stability, and water absorption capacity of poly(vinyl chloride) (PVC)/sisal fiber composites were assessed with respect to the effect of maleic anhydride chemical treatments of the sisal fiber, for five different sisal fiber contents, varying from 0 to 30% by weight in the composite. The composites prepared with the untreated sisal exhibited higher tensile modulus and hardness than the unloaded resin, while elongation and tensile strength were reduced. The deterioration in the mechanical properties of PVC blended with sisal fiber is attributed to the presence of moisture, interfacial defects at the fiber and polymer interface, and fiber dispersion in the PVC matrix. The amount of absorbed water is a function of the amount of fiber in the composite (F0 = 0 phr, F5 = 0.77 phr, and F20 = 4.83 phr). The comparison of the results of characterization of F5, F20, and F30 formulations prepared with the untreated fibers and the treated ones showed a reduction in absorbed water after the chemical treatment of fiber with maleic anhydride (F0 = 0 phr, F5 = 0.28 phr, and F20 = 2.99 phr), thus improving the mechanical properties of composites prepared with the treated sisal. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3630–3636, 2007     

The role of additives in the manufacture of sheets of unsaturated polyester and postconsumer unsaturated polyester/glass fiber composites: Mechanical and dynamic mechanical properties

The storage of postconsumer glass fiber reinforced unsaturated polyester composite impacts negatively on the environment because of the long lifetime and the volume/amount ratio of residuals, which are important aspects to be considered. Two types of additives were employed as an attempt to improve the mechanical properties of sheets manufactured with ground postconsumer glass fiber reinforced orthophthalic unsaturated polyester resin composite and virgin orthophthalic unsaturated polyester resin, a silane‐coupling agent and an organic dispersant. Flexural and impact tests, and dynamic mechanical analyses, demonstrated that the coupling agent increased the mechanical properties, while the dispersant decreased these properties, compared to material without either additive. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1834–1839, 2004