超支化聚合物对聚丙烯/剑麻纤维复合材料性能影响

为改善剑麻纤维(SF)与聚丙烯(PP)之间的相容性,在PP/SF复合材料中添加超支化聚酯(H101)、超支化环氧树脂(E102),研究了两种超支化聚合物(HBP)的热稳定性及对PP/SF复合材力学性能、熔体流动性和微观形貌的影响。热重分析表明,所使用的HBP均具有较好的热稳定性;扫描电子显微镜分析发现,HBP的加入使基体与纤维结合得更加紧密;力学性能测试表明,H101可不同程度地提高复合材料的拉伸、弯曲及冲击强度;E102可提高复合材料的拉伸及冲击强度,当E102含量为10%时,与PP/SF复合材料相比,冲击强度提高了72.24%。尽管HBP含量较高时复合材料的力学性能提高,但HBP会降低复合材料的熔体流动速率,选择HBP含量时需要综合考虑。     

改性木纤维/PVC复合材料界面及性能的研究

比较了硅烷偶联剂处理、氢氧化钠溶液浸泡与硅烷偶联剂双重处理,接枝改性等3种木纤维表面处理方法对木纤维/PVC复合材料界面及性能的影响,通过扫描电镜照片发现接枝改性木纤维在PVC基体中分散更均匀,与PVC界面相容性好.接枝改性木纤维/PVC复合材料的拉伸强度、冲击强度、断裂伸长率等力学性能有明显提高.最后分析了木纤维接枝改性处理时引发剂用量对复合材料力学性能的影响.     

纤维增强复合材料的界面力学性能测定方法

本文简述了当前测定纤维增强复合材料界面力学性能的方法。     

剑麻纤维/酚醛树脂复合材料力学性能的研究

采用剑麻纤维(SF)与酚醛树脂(PF)混合、辊炼、模压成型,制备SF/PF复合材料,并对其复合材料的冲击强度、弯曲强度、弯曲模量等进行测试。结果表明,剑麻纤维的表面处理方式、纤维的含量、纤维的长度以及与玻璃纤维混杂对复合材料体系力学性能影响较大。     

改性棉籽蛋白对天然橡胶复合材料性能的影响

将间苯二酚-甲醛改性棉籽蛋白等量代替炭黑填充天然橡胶(NR),利用红外光谱对棉籽蛋白和改性棉籽蛋白进行对比分析,研究了棉籽蛋白用量对橡胶复合材料静态力学性能、热空气老化性能及生热和剪切动态性能的影响。结果表明,棉籽蛋白中的氨基被取代;改性蛋白质低于9份时NR的综合力学强度增加,回弹性提高,抗老化性能提高;改性蛋白质使橡胶复合材料的生热性能降低,储能模量升高,损耗因子降低。     

短切苎麻/剑麻纤维增强聚酯及酚醛复合材料的性能研究

本文采用偶联剂A-151、KH-550对苎麻、剑麻纤维进行了偶联处理，比较分析了纤维表面处理前后苎麻、剑麻纤维增强不饱和聚酯及酚醛树脂复合材料的力学性能。结果表明，纤维偶联处理后，复合材料的力学性能有明显提高，吸水率有所降低。     

自制界面相容剂对木粉/PE-HD复合材料性能的影响

在实验室自制界面相容剂硅烷接枝聚乙烯( VTMS-g-PE),马来酸酐接枝聚乙烯(MA-g-PE),硅烷和马来酸酐混合接枝聚乙烯( VTMS,MA-g-PE),并将其作为木粉与PE-HD的相容剂,制备复合材料,以此来讨论复配接枝的相容剂对复合材料力学性能的影响.结果表明:界面相容剂的加入使复合体系的力学性能有不同程度的改善,其中VTMS,MA-g-PE对复合体系的力学性能改善最好,这是硅烷与马来酸酐发生了协效作用.SEM照片证实了界面相容剂的确改善了木粉与PE-HD的相互粘接,提高了体系的相容性.     

PBS/剑麻复合材料制备与性能研究

利用蒸汽爆破预处理剑麻纤维(SESF)作为增强体,通过模压成型制备聚丁二酸丁二醇酯(PBS)/SESF复合材料,研究了SESF质量分数对复合材料力学性能的影响。对比了在剑麻纤维质量分数为30%的条件下,和未经预处理的2种剑麻纤维制得的复合材料的力学性能,并通过扫描电镜(SEM)对试样进行观察分析。结果表明,随着SESF质量分数的增加,复合材料的拉伸强度先增大后减小,在SESF质量分数为30%时达到最大值,比纯PBS的提高了15.5%;弯曲强度和弯曲模量均随剑麻纤维质量分数的增大而提高,其中弯曲强度在SESF质量分数为30%时的比纯PBS的提高了132.5%;断裂伸长率和冲击强度随着SESF质量分数的增加而降低。     

界面结合对GF/PDCPD复合材料性能的影响

界面结合性能对制备性能优异的复合材料具有重要意义。通过对双环戊二烯（DCPD）与玻璃纤维（GF）的浸润性进行研究，将其与等效环氧树脂比较，开发了一种与玻璃纤维具有较好结合性的DCPD树脂，用其制备出一种综合性能优异的玻璃纤维增强PDCPD基复合材料。通过动态接触角、90?拉伸强度和层间剪切强度实验，测定了不同树脂与玻璃纤维之间的粘附力，提供了玻璃纤维与不同树脂界面性能差异。结果表明，SCB-600 DCPD树脂与玻璃纤维的结合性较优，动态接触角为60.35??0.3?，90?拉伸强度为(42.3?1.6) MPa，层间剪切强度为(61.3?3.2) MPa，与1564环氧树脂相当。进一步优化了DCPD树脂质量分数，当树脂质量分数为30%?2%时，SCB-600 DCPD复合材料具有相对最优的力学性能，材料拉伸强度为(1180.1?4.1) MPa，弯曲强度为(1060.4?4.6) MPa，缺口冲击强度为(145.3?4.8) KJ/m2。其弯曲和拉伸强度与玻璃纤维增强环氧树脂基复合材料的性能基本相当，但缺口冲击强度优于1564环氧树脂。     

天然纤维增强不饱和聚酯复合材料的界面研究进展

天然纤维具有强度高、环境友好、密度小、成本低等优点,可替代玻璃纤维或碳纤维作为不饱和聚酯树脂的增强材料。由于天然纤维与不饱和聚酯的界面结合较差,复合材料的机械性能不高,通常采取物理或化学的方法对其进行预处理,以提高纤维与基体之间的界面结合强度。本文总结了天然纤维常用的几种表面改性方法及其对不饱和聚酯树脂的增强效果。     

Foam processability of polypropylene/sisal fiber composites having near-critical fiber length for acoustic absorption properties

The current research aims to develop a sound-absorbing material from polypropylene (PP) and sisal fibers (SFs). The study explores the foam processability of PP/SF composites with near-critical fiber length, employing supercritical CO₂-assisted batch foaming technology. Optimized foam processing conditions were determined to be 145°C, 100 bar, and 15 min saturation time. These conditions resulted in foams with the lowest density, maximum volume expansion ratio and an overall microcellular structure. Notably, increasing the fiber concentration significantly enhanced the compressive properties, exhibiting a remarkable 3000% improvement with the addition of 40 wt% SFs. Dynamic mechanical analysis further revealed improved dampening properties of the composites after foaming. Moreover, the incorporation of SFs led to an increase in the noise reduction coefficient, while foaming additionally improved the sound absorption properties. This renders the material highly applicable for soundproofing purposes. Thus, produced PP/SF microcellular foams offer properties that can potentially be used to produce lightweight structural components for acoustic absorption applications.     

Preparation and characterizations of polycaprolactone/green coconut fiber composites

The mechanical, thermal, and morphological properties of polycaprolactone (PCL) and green coconut fiber (GCF) composites were evaluated. Blends containing acrylic acid‐grafted PCL (PCL‐g‐AA/GCF) exhibited noticeably better mechanical properties due to better compatibility between the two components. The dispersion of GCF in the PCL‐g‐AA matrix was significantly more homogeneous due to the creation of branched and cross‐linked macromolecules via reactions between carboxyl groups in PCL‐g‐AA and hydroxyl groups in GCF. The tensile strength of the PCL‐g‐AA/GCF composites at break was considerably greater than that of PCL/GCF composites. In addition, the PCL‐g‐AA/GCF blend was more easily processed due to lower melt viscosity. Biodegradation tests were performed with each composite in an Acinetobacter baumannii BCRC 15556 environment. The mass of both composites was reduced by the GCF content within 4 weeks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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 EVA–sisal fiber composites

In this work, composites of an EVA polymer matrix and short sisal fiber were characterized. The physical‐morphological as well as chemical interactions between EVA and sisal were investigated. When the samples were prepared in the presence of dicumyl peroxide, the results suggest that crosslinking of EVA as well as grafting between EVA and the sisal fibers took place. Morphological changes were studied by scanning electron microscopy (SEM). Results from Hg‐porosimetry, SEM, Fourier transform infrared spectroscopy, surface free energy, and gel content strongly indicate grafting of EVA onto sisal under the composite preparation conditions, even in the absence of peroxide. The grafting mechanism could not be confirmed from solid‐state ¹³C NMR analysis. The grafting had an impact on the thermal and mechanical properties of the composites, as determined by differential scanning calorimetry and tensile testing. Thermogravimetric analysis results show that the composites are more stable than both EVA and sisal fiber alone. The composite stability, however, decreases with increasing fiber content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1607–1617, 2006     

Structure and properties of UHMWPE fiber/carbon fiber hybrid composites

Ultrahigh molecular weight polyethylene (UHMWPE) fiber/carbon fiber hybrid composites were prepared by inner‐laminar and interlaminar hybrid way. The mechanical properties, dynamic mechanical analysis (DMA), and morphologies of the composites were investigated and compared with each other. The results show that the hybrid way was the major factor to affect mechanical and thermal properties of hybrid composites. The resultant properties of inner‐laminar hybrid composite were better than that of interlaminar hybrid composite. The bending strength, compressive strength, and interlaminar shear strength of hybrid composites increased with an increase in carbon fiber content. The impact strength of inner‐laminar hybrid composite was the largest (423.3 kJ/m²) for the UHMWPE fiber content at 43 wt % to carbon fiber. The results show that the storage modulus (E′), dissipation factor (tan δ), and loss modulus (E″) of the inner‐laminar hybrid composite shift toward high temperature remarkably. The results also indicate that the high‐performance composite with high strength and heat resistance may be prepared by fibers' hybrid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1880–1884, 2006     

Influence of fiber volume fraction and aspect ratio in resol–sisal composites

Vegetable fibers are being used as reinforcements in polymeric matrices with a wide variety of applications. Among these fibers, sisal is of particular interest due to the high impact strength and moderate tensile and flexural properties of its derivated composites. Because of its low cost and affinity, a phenol–formaldehyde resin, resol, has been selected as the matrix to obtain resol–sisal composites. The influence of fiber length and volume fraction on flexural properties has been studied. An optimum for the fiber length as well as for the fiber volume fraction was found. The improvement of the properties occurred up to a length of about 23 mm. The use of longer fibers lead to reduced properties because they tended to curl and bend during processing. Besides, actual composite densities were lower than theoretical ones mainly due to the presence of voids. This undesirable porosity produced a reduction in flexural properties at high fiber contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2714–2722, 2003     

Morphology and properties of polystyrene/agave fiber composites and foams

In this work, agave fibers were blended with polystyrene to produce foamed and unfoamed composites. The effect of fiber size and density reduction on the morphological, thermal, mechanical, and rheological properties, as well as crystallinity and water absorption kinetics of the composites was assessed. The results show that Young's modulus and tensile strength increased with increasing fiber content, but decreased with density reduction. Increasing fiber content and decreasing the size of the fibers both increased crystallinity of the composites. Finally, water uptake and diffusion coefficient were found to increase with increasing fiber content for all sizes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical properties of biorenewable fiber/plastic composites

Plastic fiber composites, consisting of polypropylene (PP) or polyethylene (PE), and pinewood, big blue stem (BBS), soybean hulls, or distillers dried grain and solubles (DDGS), were prepared by extrusion. Young's modulus, tensile and flexural strengths, melt flow, shrinkage, and impact energy, with respect to the type, amount, and size of fiber on composites, were evaluated. Young's moduli under tensile load of wood, BBS, and soybean‐hull fiber composites, compared with those of pure plastic controls, were either comparable or higher. Tensile strength significantly decreased for all the PP/fiber composites when compared with that of the control. Strength of BBS fiber composites was higher than or comparable to that of wood. When natural fibers were added there was a significant decrease in the melt flow index for both plastic/fiber composites. There was no significant difference in the shrinkage of all fiber/plastic composites compared to that of controls. BBS/PE plastic composites resulted in higher notched impact strength than that of wood or soybean‐hull fiber composites. There was significant reduction in the unnotched impact strength compared to that of controls. BBS has the potential to be used as reinforcing materials for low‐cost composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2484–2493, 2004     

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