The effect of fiber concentration on mechanical and thermal properties of fiber‐reinforced polypropylene composites

A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene‐co‐ethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP–PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) with reference to the fiber concentration. Although, by increasing PP fiber concentration in PPE, no significant difference was found in melting and crystallization temperatures of the PPE, the storage, and the tensile and flexural modulus of the composites increased linearly with fiber concentrations up to 50%, 1.5, 1.0, 1.3 GPa, respectively, which was approximately four times higher than that for the pure PPE. There is a shift in glass transition temperature of the composite with increasing fiber concentration in the composite and the damping peak became flatter, which indicates the effectiveness of fiber–matrix interaction. A higher concentration of long fibers (>50% w/w) resulted in fiber packing problems, difficulty in dispersion, and an increase in void content, which led to a reduction in modulus. Cox–Krenchel and Haplin–Tsai equations were used to predict tensile modulus of random fiber‐reinforced composites. A Cole–Cole analysis was performed to understand the phase behavior of the composites. A master curve was constructed based on time–temperature superposition (TTS) by using data over the temperature range from −50 to 90°C, which allowed for the prediction of very long and short time behavior of the composite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2260–2272, 2005     

Hybrid fiber fabric composites from poly ether ether ketone and glass fiber

Poly ether ether ketone (PEEK) polymer was extruded into filaments and cowoven into unidirectional hybrid fabric with glass as reinforcement fiber. The hybrid fabrics were then converted into laminates and their properties with special reference to crystallization behavior has been studied. The composite laminates have been evaluated for mechanical properties, such as tensile strength, interlaminar shear strength (ILSS), and flexural strength. The thermal behavior of the composite laminates were analyzed using differential scanning calorimeter, thermogravimetric analyzer, dynamic mechanical analyzer (DMA), and thermomechanical analyzer (TMA). The exposure of the fabricated composite laminates to high temperature (400 and 500°C) using radiant heat source resulted in an improvement in the crystallanity. The morphological behavior and PEEK resin distribution in the composite laminates were confirmed using scanning electron microscope (SEM) and nondestructive testing (NDT). Although DMA results showed a loss in modulus above glass transition temperature (T_g), a fair retention in properties was noticed up to 300°C. The ability of the composite laminates to undergo positive thermal expansion as confirmed through TMA suggests the potential application of glass–PEEK composites in aerospace sector. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117:1446–1459, 2010     

增容PP/废弃PET织物纤维复合材料的结构与性能

用马来酸酐接枝聚丙烯(PP-g-MAH)、甲基丙烯酸甲酯和苯乙烯的混合物(MMA/St)两种相容剂对PP和废弃的PET织物(WF)复合材料界面进行改性,研究其力学性能、微观形态和热行为.结果表明:WF的加入使PP的拉伸强度下降,但改善了弯曲强度和模量,更使冲击强度大幅提升.在高WF填充量时,PP-g-MAH改性有助于改善弯曲性能和韧性,MMA/St混合物改性则对拉伸性能和弯曲性能更有利.挤出共混可使WF织物在PP中实现单纤维分散,PP-g-MAH和MMA/St改性改善了WF和PP的分散和界面粘结,MMA/St改性效果更优.这3类PP/WF复合材料的热稳定性都有所提高.     

固相剪切碾磨制备高填充聚丙烯木塑复合材料的形貌结构与力学性能

利用磨盘形力化学反应器优异的粉碎、分散、混合和力化学反应的多重功能以及增容剂PP-g-MAH的良好增容作用制备了综合性能优良的聚丙烯(PP)/木粉(WF, 80%,质量分数)高填充木塑复合材料,研究了磨盘碾磨、增容剂以及复合方式对PP/WF木塑复合体系的粒径分布、力学性能和形貌结构等的影响.结果表明,不同碾磨次数的PP/WF复合粉体的粒径呈双峰分布,适当增加碾磨次数有利于PP粒径的降低及木粉的均匀分散.随碾磨次数的增加,PP/WF复合材料的拉伸和弯曲性能先增加后下降,但缺口冲击强度一直呈小幅下降趋势.PP-g-MAH的引入及其含量增加均有利于PP/WF复合材料力学性能的大幅改善,其中弯曲模量在增容剂含量为5%(质量分数)时最佳.此外,磨盘碾磨制备的PP/WF复合材料的力学性能优于常规密炼复合法.上述力学性能变化归因于磨盘碾磨改善了PP/WF高填充复合体系中木粉的分散性以及加入的PP-g-MAH显著改善了体系的相容性,其中PP-g-MAH的增容机理为磨盘碾磨剪切力场作用下PP-g-MAH与木粉表面羟基发生了力化学酯化接枝反应.     

The influence of addition of carbon nanotube and graphene platelets on characteristics of carbon/basalt fiber reinforced intra-ply hybrid composites

In this study, effects of addition of carbon nanotubes (CNTs) and graphene platelets (GPLs) on characteristics of carbon/basalt fiber reinforced intra-ply hybrid composites were investigated. The composites were fabricated using vacuum assisted resin infusion molding (VARIM) method in two types including bare and 0.1, 0.5 wt.% of GPL and CNT nanoparticles filled hybrid composites. Fabricated normal and multiscale composites were cut by water jet and mechanical properties of specimens were examined by tensile, flexural, SBS experiments. Therefore, the modulus of elasticity, flexural modulus, tensile and flexural strength and ILSS of bare and multiscale composites were compared. Thermomechanical properties of fabricated composites were evaluated by dynamic mechanic analyze (DMA), thermogravimetric analyze ( TGA) and thermal conductivity (TC) tests and storage modulus, loss modulus, damping ratio, glass transition temperature, weight loss and derivative weight loss were compared in fabricated normal and multiscale composites. Similarly, modal properties of fabricated composites such as natural frequency and damping factor were obtained by vibrational tests and compared in fabricated composites. According to the results, the addition of carbon-based nanoparticles improved the characteristics of carbon/basalt fiber intra-ply hybrid composites. The response of composites was directly proportional to the addition ratio of the carbon-based nanoparticles.     

玻璃纤维增强煤基抗冲共聚聚丙烯的性能

采用双螺杆挤出共混法制备了短玻璃纤维(GF)改性聚丙烯(PP)2240S的共混物,通过力学性能分析测试、扫描电子显微镜表征、熔体流动速率测试和熔融结晶分析等研究了改性体系的力学性能、显微结构、加工流动性和结晶性能等。结果表明,当GF添加量为30%时,复合体系的弯曲强度、弯曲弹性模量、拉伸强度等较纯PP分别提高约112%,269%和108%,但GF与基体粘结力弱导致冲击强度没有提高;为进一步改善界面作用力,以5%马来酸酐接枝聚丙烯作相容剂,相同GF添加量下PP的弯曲强度达86.99 MPa,弯曲弹性模量达5073 MPa,拉伸强度达78.5 MPa,简支梁缺口冲击强度达14.78 kJ/m2,比纯PP的相关指标分别提高约161%,302%,190%和131%,GF与PP界面粘结力增强,PP的力学性能随GF含量的递增而大幅提高。但GF降低了PP的熔体流动速率,并且体系的结晶温度基本未变,结晶度降低,可能与未产生界面横晶有关。     

Morphological,mechanical, and physical properties of composites made with wood flour‐reinforced polypropylene/recycled poly(ethylene terephthalate) blends

Wood flour (WF)‐filled composites based on a polypropylene (PP)/recycled polyethylene terephthalate (r‐PET) matrix were prepared using two‐step extrusion. Maleic anhydride grafted polypropylene (MAPP) was added to improve the compatibility between polymer matrices and WF. The effects of filler and MAPP compatibilization on the water absorption, mechanical properties, and morphological features of PP/r‐PET/WF composites were investigated. The addition of MAPP significantly improved mechanical properties such as tensile strength, flexural strength, tensile modulus, and flexural modulus compared with uncompatibilized composites, but decreased elongation at break. Scanning electron microscopic images of fracture surface specimens revealed better interfacial interaction between WF and polymer matrix for MAPP‐compatibilized PP/r‐PET/WF composites. MAPP‐compatibilized PP/r‐PET/WF composites also showed reduced water absorption due to improved interfacial bonding, which limited the amount of absorbable water molecules. These results indicated that MAPP acts as an effective compatibilizer in PP/r‐PET/WF composites. POLYM. COMPOS., 38:1749–1755, 2017. © 2015 Society of Plastics Engineers     

Mechanical properties and dynamic mechanical analysis of thermoplastic‐natural‐rubber‐reinforced short carbon fiber and kenaf fiber hybrid composites

The hybridization of thermoplastic natural rubber based on carbon fiber (CF) and kenaf fiber (KF) was investigated for its mechanical and thermal properties. Hybrid composites were fabricated with a melt‐blending method in an internal mixer. Samples with overall fiber contents of 5, 10, 15, and 20 vol % were subjected to flexural testing, and samples with up to 30% fiber content were subjected to impact testing. For flexural testing, generally, the strength and modulus increased up to 15 vol % and then declined. However, for impact testing, higher fiber contents resulted in an increment in strength in both treated and untreated composites. Thermal analysis was carried out by means of dynamic mechanical analysis on composites with 15 vol % fiber content with fractions of CF to KF of 100/0, 70/30, 50/50, 30/70, and 0/100. Generally, the storage modulus, loss modulus, and tan δ for the untreated hybrid composite were more consistent and better than those of the treated hybrid composites. The glass‐transition temperature of the treated hybrid composite was slightly lower than that of the untreated composite, which indicated poor damping properties. A scanning electron micrograph of the fracture surface of the treated hybrid composite gave insight into the damping characteristics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

玄武岩纤维增强聚丙烯复合材料性能研究

以聚丙烯(PP)树脂为基体,加入玄武岩纤维(BF)和相关助剂,通过双螺杆挤出机熔融共混制得相应复合材料。考查相容剂对PP/BF复合材料性能影响、对PP/BF复合材料和PP/玻璃纤维(GF)复合材料力学性能、微观形貌和耐热氧老化等性能进行对比。通过实验数据分析,加入相容剂后,拉伸强度提高126.8%,弯曲强度提高223.8%,弯曲弹性模量提高119.9%,悬臂梁缺口冲击强度提高223.2%。在同样质量配比下,PP/BF复合材料较PP/GF复合材料拉伸强度提高9.8%,弯曲强度提高11.0%,弯曲弹性模量提高5.8%,悬臂梁缺口冲击强度降低10.7%。从微观电镜分析,加入相容剂可明显改善纤维与PP基材界面浸润程度。另外,BF比GF更易使复合材料老化,常规热氧老化剂1010和168对纤维增强PP类材料耐老化效果并不好,用等量自制热氧老化剂可解决此问题。     

Effect of woody biomass surface free energy on the mechanical properties and interface of wood/polypropylene composites

The aim of this study is to investigate the effect of surface free energy of wood flour (WF) and silanized WF on the mechanical properties and interface of wood/polypropylene (PP) composites. The contact angles of three probe liquids against unmodified and modified spruce WF were tested by capillary rise method based on the Washburn equation. Then the surface free energy and its corresponding dispersion and polar components were calculated according to the method developed by Owens–Wendt–Kaelble. The tensile strength and flexural strength of the wood/PP composite samples made with unmodified and modified WF were tested and the flexural fracture surfaces were analyzed by scanning electron microscopy (SEM). The results showed that the surface free energy of WF increased from 26.0 to 36.1?mJ/m², which was higher than that of PP (29.4?mJ/m²), and its corresponding polar component decreased from 13.1 to 4.4?mJ/m², and the dispersion component increased from 12.9 to 31.7?mJ/m² after the modification with 4 wt.% vinyltriethoxy silane, which makes it possible for spreading of PP on the surface of WF, the tensile strength and flexural strength of wood/PP composites made with modified WF were obviously improved. In addition, the improved compatibility between WF and PP was well confirmed by SEM.     

剑麻纤维/长玻纤混杂增强PP复合材料的力学性能研究

采用剑麻纤维(SF)和长玻璃纤维(LGF)混杂增强聚丙烯(PP)复合材料,考察了SF/LGF的比例和含量对PP复合材料力学性能的影响。结果表明:SF/LGF在聚丙烯树脂基体中呈交叉网状分布,这有利于提高复合材料的冲击强度、弯曲模量、拉伸强度和软化点。在SF/LGF质量比为2 2∶,二者总质量分数为30%时,SF/LGF混杂增强PP复合材料的综合力学性能较好。     

空心玻璃微珠对碳纤维增强聚丙烯性能的影响研究

以碳纤维(CF)增强聚丙烯(PP)作为基础材料,添加空心玻璃微珠(GB)对其进行共混改性,研究GB的加入量对其流动性能和力学性能的影响。转矩流变性能、拉伸性能、冲击性能和微观形貌的分析与研究结果表明,GB对PP/CF复合材料具有增强增韧的作用。     

Si-69改性白炭黑增强受阻酚／丁腈橡胶复合材料的制备与性能研究

在丁腈橡胶（NBR）中加入受阻酚AO—80和不同份数Si-69改性的白炭黑,制备了NBR／AO-80／白炭黑／Si-69复合材料。利用差示扫描量热（DSC）,动态力学分析（DMA）,力学性能测试等手段对复合材料动态力学性能及力学性能进行了研究。结果表明：与纯NBR相比。复合材料玻璃化转变温度向高温移动。损耗峰峰值有所降低,损耗峰位置向高温移动,有效阻尼温度区域有所拓宽,其损耗峰峰值高于1．25。有效阻尼温度区域（≥0．3）大于32℃,表明复合材料具有良好阻尼性能;与NBR／AO-80复合材料和纯NBR相比,复合材料力学性能有大幅度提高,拉伸强度达到28．3MPa,撕裂强度达到44．8kN／m。     

Mechanical and Morphological Properties of PP/LLPDE/NR Blends—Effects of Polyoctenamer

In this study, impact-modified polypropylene (PP) ternary blends based on PP/natural rubber (NR)/linear low-density polyethylene (LLDPE) with ratios of 72/10/18 and 64/20/16 were produced by a twin-screw extruder with polyoctenamer (TOR) as the compatibilizer. The mechanical properties of the blends were determined on injection-molded specimens in tensile, flexural, and impact testing. The impact strength and elongation at break of the blend increased significantly while the flexural modulus and tensile strength decreased slightly with increasing TOR content. The impact strength improved with the increasing TOR due the increase of interfacial adhesion resulting in finer dispersion of the rubbery minor phase in the PP matrix. The improvement in compatibility with the addition of TOR into PP/NR/LLDPE blends is being supported by both scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA).     

Influence of a Rare-Earth Coupling Agent on the Interfacial Interaction of Wood Flour/Polypropylene Composites

Abstract

In this article, the influence of a rare-earth (RE) coupling agent on the interfacial interaction of wood flour/polypropylene composites (WF/PP) was investigated by studying the rheology behavior and the mechanical properties and using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The increased equilibrium torque results implied that the composites had a greater frictional shear force, which probably resulted from strong adhesion at the interface between the WF and PP. The mechanical property results showed that the added RE improved: the tensile strength by 42.6%; the flexural strength by 66.7%; and the impact strength by 92.3%, when compared to the WF/PP composites containing no RE material. According to the DSC results, the addition of the RE decreased the crystallization temperature and melting temperature. These results showed that the RE improved the interfacial adhesion. This was further confirmed by the SEM analysis of the composites.     

Effects of styrene-isoprene copolymer glass fiber coatings on woven glass cloth epoxy composite performance

Woven glass-epoxy composites were prepared from mats that had been treated in a variety of ways. Fibers were coated with a commercial sizing, no sizing, and a surfactant coating. In addition, fibers were coated with styrene-isoprene copolymers at varying molar ratios using a novel technique termed admicellar polymerization. Dynamic contact angle measurements were used to quantify the effect of the different coating techniques on the fiber, while dynamic mechanical analysis (DMA) and flexural testing were used to characterize the cured composites. Wetting studies conducted with EPON 828 resin revealed no difference in wetting for the polymer-treated fiber compared to the commercially-treated fiber. Aqueous wetting results were consistent with a surfactant layer adsorbed on the polymer treated and surfactant treated fiber surface. DMA established that both the polymer and surfactant treatment depressed the alpha transition temperature of the composite and suggested an interpenetrating network existed at the fiber-matrix interface. Flexural strength testing showed the properties of the composites made from surfactant-treated and polymer-treated glass fibers were comparable to composites made from commercially-sized fibers and exceeded the flexural strength of the composite made from glass fibers without sizing.     

Effect of lactic acid chain length on thermomechanical properties of star‐LA‐xylitol resins and jute reinforced biocomposites

Star‐shaped bio‐based resins were synthesized by direct condensation of lactic acid (LA) with xylitol followed by end‐functionalizing of branches by methacrylic anhydride with three different LA chain lengths (3, 5 and 7). The thermomechanical and structural properties of the resins were characterized by ¹³C NMR, Fourier transform IR spectroscopy, rheometry, DSC, dynamic mechanical analysis (DMA), TGA and flexural and tensile tests. An evaluation of the effect of chain length on the synthesized resins showed that the resin with five LAs exhibited the most favorable thermomechanical properties. Also, the resin's glass transition temperature (103 °C) was substantially higher than that of the thermoplast PLA (ca 55 °C). The resin had low viscosity at its processing temperature (80 °C). The compatibility of the resin with natural fibers was investigated for biocomposite manufacturing. Finally, composites were produced from the n5‐resin (80 wt% fiber content) using jute fiber. The thermomechanical and morphological properties of the biocomposites were compared with jute‐PLA composites and a hybrid composite made of the impregnated jute fibers with n5 resin and PLA. SEM and DMA showed that the n5‐jute composites had better mechanical properties than the other composites produced. Inexpensive monomers, good thermomechanical properties and good processability of the n5 resin make the resin comparable with commercial unsaturated polyester resins. © 2017 Society of Chemical Industry     

Mechanical,flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites

Polypropylene (PP) hybrid composites have been produced by compounding two types of mineral fillers, viz., talc and kaolin with PP copolymer using a twin screw extruder. The PP hybrid composite was injection‐molded into dumbbell specimen for tensile, flexural, and impact properties characterizations. MFI and SEM studies were used to characterize the flow and morphological properties of the PP hybrid composites. The result shows that most of the hybrid composites showed a significant decrease in flow, tensile, flexural, and impact properties compared with the single filler‐filled PP composites. However, a hybridization effect was seen for the PPT20K10 hybrid composites, through the synergistic coalescence of positive characteristics from 20 wt % of talc and 10 wt % of kaolin. This hybrid formulation have given an economically advantageous material with the mechanical properties (tensile, flexural, and impact) comparable to those of the talc‐filled PP composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 434–441, 2007     

Preparation and Properties of PB-1/PP Blends

Crystallization behavior, dynamic mechanical properties, mechanical properties and rheological properties of isotactic polybutene-1/polypropylene (PB-1/PP) blends prepared by melt-blending the two components through Brabender extruder were mainly studied via POM, DSC, DMA, capillary rheometer and so on, respectively. The results indicated that after adding PP in PB-1: size of the spherical crystal and degree of crystallization of PB-1 in the blends decreased, its melt temperature and crystallization temperature unchanged; tensile property of the blends was decreased, but impact and flexural properties were improved; change of the melt viscosity of the blends with the shear rate was more sensitive than pure PB-1.     

玻纤增强聚丙烯复合材料性能研究

研究了玻纤(GF)、SEBS和聚丙烯接枝马来酸酐(PP-g-MAH)用量对GF增强聚丙烯复合材料性能的影响,以及PP/GF(65/35)、PP-g-MAH/PP/GF(15/65/35)的微观形态。结果表明:随着GF用量的增加,复合材料的拉伸强度、弯曲强度和弯曲模量增加,断裂伸长率降低,冲击强度先减小后增大,PP/GF复合材料断面呈脆性断裂;在PP/GF中添加增韧剂SEBS可以提高复合材料的冲击强度,但拉伸强度、断裂伸长率、弯曲强度和弯曲模量均减小;在PP/GF中添加增容剂PP-g-MAH,可使其拉伸强度、断裂伸长率、弯曲强度、弯曲模量和冲击强度均得到提高,当PP-g-MAH/PP/GF为15/65/35时,复合材料性能优异,材料断面呈韧性断裂。