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1.
Caroline Pigatto Jos Humberto Santos Almeida Heitor Luiz Ornaghi Adriane Lawisch Rodríguez Cludia Mendes Mhlmann Sandro Campos Amico 《Polymer Composites》2012,33(12):2262-2270
Thermoplastics reinforced with natural fibers have attracted much attention from researchers because of their advantages, especially regarding environmental aspects. However, poor impact strength, particularly at low temperatures, limits the application of some thermoplastics, such as polypropylene (PP). To minimize this drawback, impact modifiers have been used, including the terpolymer of ethylene‐propylene‐diene (EPDM). In this work, PP/EPDM/sisal composites of distinct compositions were investigated focusing on the effect of the alkali (NaOH) treatment of the vegetable fiber on the composites properties regarding physical, mechanical, thermal, and morphological behavior. The results indicated that flow rate decreases at higher fiber content due to flow hindering by the presence of the fibers. The addition of the fiber, in general, increased Young's modulus and strength (tensile and flexural), whereas impact strength increased for higher EPDM content. The alkali treatment was considered generally efficient in terms of mechanical properties, even though this was not found in the dynamic mechanical analysis. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
2.
This study investigates the mechanical properties of wood-fiber/toughened PP composite modified by physical blending with an EPDM rubber to improve impact toughness. Wood-fiber thermoplastic composites were prepared with a modified PP matrix resin, employing high shear thermokinetic compounding aided with maleated PP for the fiber dispersion. The addition of EPDM improved the impact toughness, while it reduced stiffness and strength properties. To compensate the non-plane strain fracture toughness, the specimen strength ratio (Rsb) was adopted as a comparative measure of fracture toughness. The strength ratio increased with the addition of EPDM, while it decreased with increasing wood-fiber concentration. The work of fracture increased with EPDM level except at large wood-fiber concentration. The effectiveness of the impact modification was assessed with the balance between tensile modulus and unnotched impact energy as a function of wood-fiber concentration. EPDM rubber modification was moderately effective for wood-fiber PP composites. The examination of fracture surfaces showed twisted fibers, fiber breakage, and fiber pull-out from the matrix resin. 相似文献
3.
The enhancement of the mechanical properties of neat PP is achieved by the addition of glass fibers and EPDM rubber. The Young's modulus and notched Charpy impact strength of the composites obtained are improved with respect to the original polymer, leading to a new composite material with a very good balance of toughness and rigidity properties. The tensile behavior of these multiphase systems is successfully compared with theoretical predictions using the Halpin‐Tsai/Nielsen theory for uniaxially short fiber composites, which considers the matrix as a blend with spherical particles and can predict the tensile modulus considering an average fiber orientation angle. An accurate morphological study performed by scanning electron microscopy (SEM) shows a very good dispersion of the rubbery phase into the neat matrix. No special affinity between the rubber and the fibers is reported. The good dispersion and the small particle diameter indicate the good processability of the ternary systems studied. 相似文献
4.
The effect of aramid, glass and cellulose short fibers on the processing behavior, crosslinking density and mechanical properties of natural rubber (NR), ethylene‐propylene‐diene terpolymer rubber (EPDM) and styrene‐butadiene rubber (SBR) has been investigated. Two fiber percentages (10 and 20 phr) were added to the rubber. The results have shown that the above‐mentioned fibers, especially aramid fibers, are effective reinforcing agents for these rubbers, giving rise to a significant increase in mechanical properties, such as tensile modulus and strength, and tear and abrasion resistance. Moreover, a significant decrease in the time to reach 97% of curing, t′c (97) is observed, which indicates that the fibers tend to increase the vulcanization rate, regardless of the rubber used. Fibers give also rise to an increase in crosslinking, especially the aramid fibers. 相似文献
5.
In order to improve the compatibility between natural fibers and polypropylene (PP) and polypropylene‐ethylene propylene diene terpolymer (PP‐EPDM) blends, the functionalization of both matrices with maleic anhydride (MA) is investigated in this study. The morphological observations carried out by scanning electron microscopy show that the incorporation of small amounts of functionalized polymer considerably improves the adhesion at the fiber‐matrix interface. In these cases, the fibers are perfectly embedded in the matrix in relation to the composites prepared with the pure homopolymers, and a significant increase in the composite strength is also observed, particularly, after the incorporation of both modified polymers (MAPP and MAEPDM). Thus, it is possible to correlate better interfacial adhesion with the improvement of mechanical properties. It is assumed that the functionalization of the matrix reduces interfacial stress concentrations and may prevent fiber‐fiber interactions, which are responsible for premature composite failure. The crystallization kinetics of PP were also analyzed by differential scanning calorimetry (DSC). It was observed that both flax fiber and rubber behave as effective nucleant agents, accelerating PP crystallization. Moreover, these results are particularly relevant when the grafted matrices are added to the composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2170–2178, 2003 相似文献
6.
为了改善芳纶纤维增强树脂基复合材料的界面粘结性能,从树脂基体入手,依据相似相容原理和芳纶的结构特点,合成出新型热固性树脂(AFR–T)用作芳纶复合材料的基体,以未经表面处理的芳纶作增强材料,采用热压成型法制备了AFR–T/芳纶纤维复合材料,并通过测定溶度参数、接触角、线膨胀系数、层间剪切强度(ILSS)和横向拉伸强度等方法研究了复合材料的界面粘结性能。结果表明,AFR–T树脂浇注体与芳纶的溶度参数相近,AFR–T树脂溶液在芳纶纸表面的接触角为36.9°,小于环氧树脂(EP)溶液与芳纶纸的接触角(53.2°),说明AFR–T树脂对芳纶的浸润性优于EP;AFR–T/芳纶纤维复合材料的ILSS和横向拉伸强度为73.0 MPa和25.3 MPa,分别比EP/芳纶纤维复合材料提高了25.9%和32.5%,这表明AFR–T树脂与芳纶纤维之间的浸润性和界面粘结性能较好。 相似文献
7.
Short poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers were first used to reinforce ethylene–propylene–diene terpolymer (EPDM) as thermal
insulation materials. The effects of PBO fiber length and content on the mechanical and ablative properties of the composites
were investigated in detail. Comparing with the severe breakage occurred in short aramid fibers as fillers, only some necking
deformation is observed in PBO fibers filled EPDM after processed. After ablated by oxyacetylene flame, the carbonized PBO
fibers still keep solid fibrous structure instead of hollow one of carbonized aramid fibers in the char layer. As a result,
the PBO fibers/composites show significantly higher tensile strength and ablation resistant abilities than the aramid fibers/composites.
Moreover, with the length and content of PBO fibers increasing, both the tensile strength and the ablation resistance of the
composites increase gradually though the break elongation reduces sharply. Considering the properties requirement of thermal
insulator, PBO fibers with 3.42–5.56 wt% in content and 3–4 mm in length are preferred. The mass loss rate and the erosion
rate as low as 0.05 g s−1 and 0.10 mm s−1 are observed in the optimal samples, respectively, which is evidently lower than that of the best aramid fibers/EPDM-based
insulations reported so far. 相似文献
8.
为了分析混杂比对层内混杂复合材料力学性能的影响,利用交织方式制备芳纶碳纤维混杂增强体织物,并通过交织物纬纱系统中芳纶与碳纤维的纱线配置比例调整碳纤维在增强体结构中的混杂比。采用真空辅助成型技术制备层内混杂结构的芳纶碳纤维混杂(ACFH)复合材料,并对复合材料的拉伸性能、弯曲性能和冲击性能进行测试。结果表明,增强体纬向系统中芳纶与碳纤维的不均质性对ACFC复合材料经方向上的拉伸强度起消极作用;混杂比的增加对ACFC复合材料的纬向拉伸破坏和弯曲损伤具有抑制作用;纬向上,ACFC复合材料的拉伸强度最高提高了近6倍,弯曲强度最小增加了4.04倍;芳纶与碳纤维混杂协同作用有利于ACFC复合材料的抗冲击性能改善,且混杂比存在最佳值。 相似文献
9.
10.
Production and characterisation of vapour grown carbon fiber/polypropylene composites 总被引:1,自引:0,他引:1
Polymeric composites are widely used in the aircraft and automotive industries. Their high strength-to-weight ratio makes significant weight reduction possible. Beside this advantage, the polymer materials also offer a good corrosion resistance but the mechanical and electrical properties are not satisfactory. In order to increase these properties, vapour grown carbon fibers (VGCF) with high strength and metal-like electrical conductivity can be embedded in the polymeric matrix. To ensure a good adhesion between the fibers and the polymer matrix a functionalization of the chemically inert surface of the fibers is necessary.In the present research work oxygen-containing functional groups were introduced on the fiber surface through cold plasma treatment. Measurements of the fiber surface energy after plasma functionalization showed an enhancement of at least 50% of the initial value. The VGCF/PP composites with different amounts of VGCF were made through extrusion and injection molding. The results show that the degree of fiber surface functionalization and the fiber distribution and orientation in the polypropylene (PP) matrix may strongly influence the mechanical properties of the composite. 相似文献
11.
Kiril P. Tchomakov Basil D. Favis Michel A. Huneault Michel F. Champagne Florin Tofan 《加拿大化工杂志》2005,83(2):300-309
The ternary blends of high‐density polyethylene (PE), EPDM terpolymer and polypropylene (PP) have been used as a model low interfacial tension system to study encapsulation dynamics in ternary blends and their relation to the blends' mechanical properties. It was found that the modulus, tensile strength and impact resistance can be improved by PE addition if the PE is localized within the EPDM phase. A range of blend morphology was found depending on the PE viscosity and polymer incorporation sequence in the twin‐screw extruder. In the most favorable sequence, PE and EPDM were mixed together prior to their dispersion in the PP matrix. This practice resulted in a 50% increase in impact resistance when compared to mixing the three components in a single‐step. 相似文献
12.
为了改善杂环芳纶(F3)与环氧树脂黏结性差以及不耐紫外辐射的缺点,首先对纤维进行功能化预处理,然后通过溶胶-凝胶法和水热法分别在芳纶表面生长了氧化锌纳米颗粒和氧化锌纳米线界面层。采用X成、形貌、与环氧树脂的黏结性以及抗紫外性能进行了研究。结果表明:纳米颗粒状和纳米线形态的ZnO纳米界面相能够显著提高纤维与树脂基体的黏结性能,与未处理的纤维相比,单纤维复合材料的界面剪切强度分别提高了14.1%和27.0%;同时ZnO的破坏,经过168 h紫外辐射试验后,纤维强度保持率从79.1%提高到96.7%。 相似文献
13.
The purpose of this study is to investigate the influence of different types of fibers on the mechanical properties of hybrid composite materials. Long and short glass fibers (GF) and different types of organic fibers, viz. aramid fiber, DuPont Kevlar‐49 (KF), liquid crystalline polymer (LCP), and vinylon (VF) in hybrid composites, were used to reinforced the high density polyethylene (HDPE) matrix. The long fiber hybrid composites were prepared in a “fiber separating and flying machine,” while the short fiber hybrid composites were prepared in an “elastic extruder.” The total amount of fibers used in both long and short fiber hybrid composites was fixed at 20 vol%. The influence of fiber content, length, and mixing ratio on mechanical properties, such as tensile, bending, Izod and high rate impact strength, as well as viscoelastic propertics in the solid state, was studied. Fracture surfaces of the materials were also examined using a scanning electron microscopy. 相似文献
14.
The interfacial adhesion between four different forms of jute fibers (sliver, bleached, mercerized and untreated) and polyolefinic matrices (LDPE and PP) was studied, as a critical factor affecting the mechanical behavior of these composites. The fiber‐matrix adhesion was estimated by means of the critical fiber length (lc) and the stress transfer ability parameter (τ); such parameters were obtained by Single Fiber Composite (SFC) tests. Tests were carried out to evaluate the mean tensile strength of the fibers, the mean critical fiber lengths and the stress transfer ability parameter for every fiber‐matrix combination, according to Weibull's statistical method. Thermal‐mechanical characterization of the fibers was also carried out to evaluate the resistance to processing conditions. A limited degradation of strength was observed, which, however, does not preclude the use of jute fibers as reinforcing means in polyolefin based composites. It was found that the adhesion was better in PP‐jute composites than in LDPE‐jute composites. In both cases the results showed that the sliver jute and the untreated jute had better adhesion to both matrices than had the bleached and the mercerized fibers. With both matrices the interface adhesion was in the order: mercerized < bleached < untreated = sliver. 相似文献
15.
利用L-3,4-二羟基苯丙氨酸(L-DOPA)的氧化自聚合,在杂环芳纶表面修饰聚L-3,4-二羟基苯丙氨酸(PDOPA)活性涂层来提高芳纶的表面活性及耐紫外辐照性能。结果表明:改性后芳纶表面粗糙度显著提高,同时,PDOPA涂层上大量的羧基、羟基等活性单元均有利于增强与环氧树脂的机械锁合力,改性后芳纶/环氧树脂复合材料的界面剪切强度提高了32.0%。此外,上述改性过程对杂环芳纶本身力学性能影响较小,纤维的拉伸强度保持率可以达到100%,基本实现了无损改性。同时,由于PDOPA的保护作用,改性后芳纶的耐紫外辐射性能显著提高;经过168 h紫外线辐照处理后,其拉伸强度保持率可达到92.5%,显著提升了杂环芳纶的耐紫外线辐照特性。 相似文献
16.
Tensile and impact properties of the ternary system polypropylene (PP)/ethylene propylene diene elastomer (EPDM)/glass fiber (GF) and the corresponding binary systems PP/EPDM blend and PP/GF composite are studied. Results are presented and analyzed as functions of compositional variables, viz., (i) matrix PP/EPDM blending ratio at constant GF loadings and (ii) GF loading at constant matrix blending ratios for the ternary system and (iii) EPDM content for PP/EPDM binary system and (iv) GF content for the binary system PP/GF, respectively. The role of individual components EPDM and GF in these mechanical properties is discussed and their combined effects are inspected at certain composition ranges. Theoretical analysis of tensile data is presented which reveals the effect of EPDM on the reinforcing effect of GF. Unlike the conventional role of an elastomer, increase of EPDM content in the presence of GF increases the modulus of the ternary system. Impact strength of the ternary system increases with increasing GF content both in the presence and absence of EPDM, showing a distinct minimum at matrix blending ratio PP/EPDM 90/10. Scanning electron micrographs of impact-fractured surfaces are presented to illustrate the dispersion of the two phases of the polyblend matrix, fiber alignment, and the fiber interface. 相似文献
17.
In this paper, aramid fiber (AF)/ethylene-propylene-diene monomer (EPDM) microcellular foams added with different content of AF are prepared by the supercritical foaming method. The effect of the AF content on the rheological behavior, mechanical properties, thermal properties and cellular structure of the AF/EPDM microcellular foams has been systematically studied. The research illustrates that compared with pure EPDM, the AF/EPDM matrix has greater viscosity and modulus, which is conducive to reduce the cell size and increase its density. And the thermal stability of EPDM foams is improved with the addition of aramid fiber. Meanwhile, when the content of AF is added to 1 wt%, the AF/EPDM microcellular foam exhibits a relatively low thermal diffusion coefficient and apparent density with the thermal conductivity to 0.06 W/mK. When the AF is added to 5 wt%, the tensile strength of the AF/EPDM microcellular foam increases to 1.95 MPa, which is improved by 47% compared with that of the pure EPDM foam. Furthermore, when the compressive strain reaches to 50%, the compressive strength of the AF/EPDM microcellular foam is 0.48 MPa, improved by 296% compared with that of the pure EPDM foam. 相似文献
18.
The toughened polypropylene (PP) was obtained by the blending of PP with ethylene‐propylene diene monomer (EPDM). The impact property of continuous glass mat‐reinforced polypropylene was adjusted through three ways: different toughness PPs and their blends were used as matrices, the functionalized polypropylene was added into the matrix to control the interfacial adhesion; the ductile interlayer was introduced at the fiber/matrix interphase by the grafting and crosslinking of rubber chains on fiber surface. The effect of PP toughness, interfacial adhesion, and ductile interlayer on the mechanical properties of composite systems was studied. The impact toughness of GMT increased with increasing the matrix toughness, whereas the flexural strength and modulus decreased. The good interfacial adhesion resulted in the low impact toughness. However, GMT composite with high strength, modulus, and impact toughness could be obtained by the introduction of a ductile interlayer at fiber/matrix interphase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2680–2688, 2002 相似文献
19.
The effect of the fiber surface modification with an azide derivative on the morphology and properties of composites based on poly(propylene) (PP) and short poly(ethylene terephthalate) (PET) and nylon 66 (PA) fibers, has been investigated. Both organic fibers act as reinforcement of the PP, and the reinforcing effect increases with the introduction of azide groups on the chemical structure of the fibers. This effect is more sensible in PP/short PET fiber composites although PA fibers gives rise to higher improvements in toughness. Scanning electron microscopy (SEM) has shown that the azide treatment of PET fibers gives rise to a better wettability and adhesion at the fiber/matrix interface. A good correlation between SEM and mechanical behavior of the composites has been observed. 相似文献
20.
Surface-induced transcrystallization in fibers has been reported in some advanced polymer composites. It is believed that transcrystalline interphase may affect stress transfer efficiency between the reinforcing fiber and the matrix. In this study, attempts were made to examine the effects of transcrystallinity on composite performance, particularly on fiber-matrix interfacial bond strength, and to investigate possible attributes of transcrystallization. Three polymer resins, poly(etherketoneketone) (PEKK), poly(etheretherketone) (PEEK), and poly(phenylenesulfide) (PPS), and four types of fiber, polyacrylonitrile (PAN)-based AU-4 (untreated AS-4) carbon, pitch-based carbon, poly (p-phenylene terephthalamide) (PPDT) aramid, and E-glass were used. It was found that PPDT aramid and pitch-based carbon fibers induce a transcrystalline interphase in all three polymers because of an epitaxial effect. Under certain conditions, transcrystallization was also observed in PAN-based carbon and E-glass fibers, which may be partially attributed to the thermal conductivity mismatch between the fiber and the matrix. Plasma treatment on fiber surface showed a negligible effect on inducing transcrystallization, whereas solution-coating of PPDT on the fiber surface showed a positive effect. The Microdebonding test, which measures the interfacial bond strength between the fiber and the matrix, consistently showed more than 40% increments for various single filament systems with transcrystalline interphase versus without. However, the effects of transcrystallinity on the interfacial bond strength appeared to decrease as the fiber content increased in composites. 相似文献