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In this paper, the effects of hyperbranched polyamide on the properties of sisal fiber reinforced polypropylene composites were studied. And the microstructure, fluidity, mechanical properties, and thermal stability of the composites were characterized. The results show that hyperbranched polyamide can significantly improve the interfacial bonding between fiber and matrix. When the fiber content is 20%, the melt flow rate can increase by 54%. Meanwhile, the tensile property of the composite increases by 50%, the impact strength of silane-treated fiber composite increases by 24%. However, the thermal stability of the composite decreases slightly after the addition of hyperbranched polyamide. [ABSTRACT FROM AUTHOR]

• Tetraethylorthosilicate sol-gel and silane combination treatment is used. • The reinforcing effect of fibers in composites is improved. • Combination treatment shows the highest interfacial shear strength. • Thermal properties of the modified fiber composites are improved. In order to prepare high performance sisal fiber reinforced polypropylene composites, this paper pays special attention to the changes of intrinsic mechanical properties of the sisal fiber so as to achieve the maximum reinforcing effect of the fiber. For achieving this aim, the sisal fibers were modified by tetraethylorthosilicate (TEOS) sol-gel method to form SiO 2 -based organic-inorganic hybrid materials. For a better result, a novel combined modification method by TEOS precursor solution and γ-aminopropyltriethoxysilane solution for the fibers was put forward and performed. Then the relevant mechanism was also analyzed in detail. The corresponding composites were prepared by melt blending with polypropylene matrix and polypropylene-graft-maleic anhydride (MAPP) compatibilizer, and the interfacial and mechanical properties of composites were studied by single fiber fragmentation test and mechanical test, respectively. The results show that the mechanical and thermal properties of the modified fiber composites are improved compared with the untreated fiber composite. The combined modification composite presents the highest interfacial shear strength, which increases by 259.49% compared with the untreated fiber composite. A good interfacial bonding is obviously observed in the combined modification composite by the analysis of scanning electron microscope (SEM). The tensile strength and modulus of the composite with the combined treatment (20 wt% fiber loading) increase by 21.72% and 28.18%; the flexural strength and modulus increase by 3.61% and 16.02%; and the impact strength increases by 21.28%. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical properties of sisal fiber-reinforced polypropylene composites, the sisal fibers were grafted with poly(amidoamine) dendrimer and the effects of grafting generations on the mechanical properties of composites were studied. The results reveal that the tensile, flexural, and impact strength of the composites are improved considerably with the poly(amidoamine) dendrimer grafting treatment. For the 2.0 generation treatment with the poly(amidoamine) dendrimer, the tensile, flexural, and impact strength of the composites at 30 wt% fiber loading increase by 29%, 13%, and 54%, respectively. However, the thermal and mechanical properties of the sisal fibers decrease after prolonged grafting treatment. [ABSTRACT FROM AUTHOR]

In this paper, the effects of fiber shape, fiber distribution, fiber size and fiber hybridization on the tensile properties of short sisal fiber-reinforced polypropylene composites were studied by the generalized method of cells and laminate analogy approaches. It is found that the fiber distribution has a large effect on the axial Young’s modulus. The fiber shape and fiber size have stronger influences on the transverse Young’s modulus and axial Poisson’s ratio than the fiber distribution. The fiber type hybridization and fiber shape are shown to be important factors in affecting the axial shear modulus. Hybridization with glass fiber is found to be an efficient method of creating high-performance composites. [ABSTRACT FROM AUTHOR]

The main objective of this article was to study the capillary effects during the impregnation of polypropylene resin in the jute fiber mats. The static equilibrium contact angles between polypropylene matrix and fibers were measured and the dynamic impregnation of matrix in the fiber mats was researched in detail. The results show that the static contact angles are clam-shell shape. The capillary effects present little values in the dynamic impregnation. The preparation for low void composites should be performed below the critical resin flow velocity of 0.13 µm/s for polypropylene resin and 0.21 µm/s for polypropylene/maleated polypropylene blend resin, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a new method based on generalized method of cells and laminate analogy approach was used to predict the elastic properties of short sisal fiber reinforced polypropylene composites. The effects of fiber volume fractions and fiber aspect ratios on the elastic properties of composites were studied by the new model and other models. Continuous fiber composite and layered composite, as two special cases were analyzed in detail by this new model. The results show that both fiber volume fraction and fiber aspect ratio have significant effects on the axial Young’s modulus. However, the fiber volume fraction has very small effects on the transverse Young’s modulus, axial shear modulus and axial Poisson’s ratio. The new model agrees better than other models with the experimental data. The elastic properties of composites with complex microstructures can be predicted efficiently by this new model. [Copyright &y& Elsevier]

In this article, the microstructures of sisal fiber composites were analyzed. The porous structure of sisal fiber, crystalline morphology of matrix and fiber distribution in composites were characterized by Voronoi diagram. The tensile properties of composites were also measured. The results show that the maleated polypropylene compatibilizer can accelerate the formation of transcrystalline interface between fibers and matrix. Improvement of interface adhesion and reduction of fiber polarity can lead to better fiber distribution in the matrix. The tensile moduli of composites are related to the degree of fiber distribution. [ABSTRACT FROM AUTHOR]