Effect of impregnation time on performance of long glass fiber‐reinforced polypropylene composites

Long glass fiber (LGF)‐reinforced polypropylene (PP) composites were prepared using self‐designed impregnation device. Effects of impregnation time on mechanical properties, crystallization, dynamic mechanical properties, and morphology of PP/LGF composites were investigated. The experiment results demonstrate that the excellent tensile strength, Notched Izod impact strength was 152.9 MPa, 31.2 KJ/m², respectively, and the stiffness of PP/LGF composites was higher, when the impregnation time was 7.03 s. The excellent interfacial adhesion between PP and glass fiber indicates that PP/LGF composites possess the outstanding mechanical properties. The impregnation time scarcely influenced thermal properties of PP/LGF composites. J. VINYL ADDIT. TECHNOL., 24:174–178, 2018. © 2016 Society of Plastics Engineers     

长玻璃纤维增强聚丙烯复合材料的力学性能研究

采用熔体浸渍技术制备了长玻璃纤维母料(LGF/PP-g-MAH/PP)增强聚丙烯(PP)复合材料(LGF/PP)。通过双螺杆挤出机制备了同等配比的短玻纤增强聚丙烯(SGF/PP)复合材料。研究了LGF含量、环氧树脂(EP)和固化剂(2E4MZ)对LGF/PP复合材料的力学性能影响。结果表明:当LGF质量分数为35%～40%时,LGF/PP的综合力学性能最好,且明显优于同样组成的SGF/PP复合材料。EP和含固化剂(2E4MZ)的EP对LGF/PP复合材料的力学性能提高有一定的作用。SEM照片分析表明:EP的加入能改善玻纤与聚丙烯基体的界面粘接。     

注塑条件对长玻纤增强聚丙烯性能影响研究

利用熔融浸渍装置,采用长玻纤(LGF)增强双马来酰亚胺等改性的聚丙烯(PP),制备了LGF增强PP复合材料。研究了在螺杆转速为80～250 r/min、背压为8～10 MPa的注塑条件下,复合材料的纤维长度、力学性能与热变形温度的变化。在研究范围内,注塑工艺参数的变化对复合材料的弯曲强度和热变形温度没有明显的影响,但随着螺杆转速的提高,纤维长度下降,所得复合材料的冲击强度先降低后升高。     

Polypropylene‐organoclay nanocomposite: Preparation,microstructure, and mechanical properties

A series of polypropylene (PP) nanocomposites containing 2, 4, and 6 wt % of an organophilic montmorillonite clay was prepared via direct melt mixing in the presence of maleic anhydride grafted polypropylene (PP‐g‐MAH) as compatibilizing agent. Microstructure characterization was performed by X‐ray diffraction analysis. Nanocomposites exhibited a 15 and 22% enhancement in tensile modulus and impact strength, respectively. The heat deflection temperature of PP nanocomposites was 36°C greater than for pure PP. Thermal and mechanical properties of nanocomposites were compared to properties of traditional PP‐talc and PP‐glass fiber composites. The results showed that the properties of nanocomposites improved compared to ordinary polypropylene composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of the chemical foaming agents,injection parameters,and melt‐flow index on the microstructure and mechanical properties of microcellular injection‐molded wood‐fiber/polypropylene composites

Wood‐fiber‐reinforced plastic profiles are growing rapidly in nonstructural wood‐replacement applications. Most manufacturers are evaluating new alternative foamed composites, which are lighter and more like wood. Foamed wood composites accept screws and nails better than their nonfoamed counterparts, and they have other advantages as well. For example, internal pressures created by foaming give better surface definition and sharper contours and corners than nonfoamed profiles have. In this study, the microfoaming of polypropylene (PP) containing hardwood fiber was performed with an injection‐molding process. The effects of different chemical foaming agents (endothermic, exothermic, and endothermic/exothermic), injection parameters (the mold temperature, front flow speed, and filling quantity), and different types of PP (different melt‐flow indices) on the density, microvoid content, physicomechanical properties, surface roughness, and microcell classification of microfoamed PP/wood‐fiber composites were studied. A maleic anhydride/polypropylene copolymer (MAH‐PP) compatibilizer was used with the intention of improving the mechanical properties of microfoamed composites. The microcell classification (from light microscopy) and scanning electron micrographs showed that an exothermic chemical foaming agent produced the best performance with respect to the cell size, diameter, and distance. The polymer melt‐flow index and the variation of the injection parameters affected the properties and microstructure of the microfoamed composites. The density of the microfoamed hardwood‐fiber/PP (with a high melt‐flow index) composites was reduced by approximately 30% and decreased to 0.718 g/cm³ with an exothermic chemical foaming agent. Tensile and flexural tests were performed on the foamed composites to determine the dependence of the mechanical properties on the density and microvoid content of the foamed specimens, and these properties were compared with those of nonfoamed composites. MAH‐PP improved the physicomechanical properties up to 80%. With an increase in the mold temperature (80–110°C), the surface roughness was reduced by nearly 70% for the foamed composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1090–1096, 2005     

Effect of alkali‐resistant glass fiber on polypropylene/polystyrene blends: Modeling and characterization

Alkali‐resistant glass fiber (GF) reinforced polypropylene (PP)/polystyrene (PS) blends were prepared by melt mixing in a Thermo Haake Rheochord mixer. Variation in thermal and mechanical properties with the addition of glass fibers into the polypropylene/polystyrene blends was investigated. The characterization of PP/PS/GF composites was done by dynamic mechanical analysis (DMA), thermogravimetric analysis, scanning electron microscope, and transmission electron microscope. The experimentally observed tensile properties of glass fiber reinforced PP/PS blends were compared with various published models. It was found that the experimental results agree well with Hui‐ Shia and series models. DMA tests revealed an increase in storage modulus with fiber loading confirms the greater degree of stress transfer from the matrix to the fiber. TEM micrographs reveal that the glass fibers are located at the interface between the blend components. POLYM. COMPOS., 37:398–406, 2016. © 2014 Society of Plastics Engineers     

Mechanical properties of injection molded long fiber polypropylene composites,Part 1: Tensile and flexural properties

Innovative polymers and composites are broadening the range of applications and commercial production of thermoplastics. Long fiber‐reinforced thermoplastics have received much attention due to their processability by conventional technologies. This study describes the development of long fiber reinforced polypropylene (LFPP) composites and the effect of fiber length and compatibilizer content on their mechanical properties. LFPP pellets of different sizes were prepared by extrusion process using a specially designed radial impregnation die and these pellets were injection molded to develop LFPP composites. Maleic‐anhydride grafted polypropylene (MA‐g‐PP) was chosen as a compatibilizer and its content was optimized by determining the interfacial properties through fiber pullout test. Critical fiber length was calculated using interfacial shear strength. Fiber length distributions were analyzed using profile projector and image analyzer software system. Fiber aspect ratio of more than 100 was achieved after injection molding. The results of the tensile and flexural properties of injection molded long glass fiber reinforced polypropylene with a glass fiber volume fraction of 0.18 are presented. It was found that the differences in pellet sizes improve the mechanical properties by 3–8%. Efforts are made to theoretically predict the tensile strength and modulus using the Kelly‐Tyson and Halpin‐Tsai model, respectively. POLYM. COMPOS., 28:259–266, 2007. © 2007 Society of Plastic Engineers     

PP/LGF复合材料的膨胀性阻燃与协效阻燃性能

采用膨胀型阻燃剂(IFR)及协效剂海泡石(SP)对长玻璃纤维增强聚丙烯(PP/LGF)复合材料进行阻燃,通过双螺杆挤出机制备了PP/LGF母粒,IFR母粒和SP母粒,然后将这3种母粒通过注塑机制备了PP/LGF/IFR/SP复合材料,通过极限氧指数(LOI)、垂直燃烧测试、锥形量热仪、热重分析、扫描电子显微镜、力学性能测试等表征PP/LGF各阻燃复合体系的性能。结果表明,当IFR质量分数为22%时,PP/LGF/IFR阻燃复合材料的LOI为28.8%,且垂直燃烧等级达到V–0级;锥形量热仪测试结果表明加入IFR及SP后阻燃复合体系的第一热释放速率峰值降低,而第二热释放速率峰消失;SP质量分数为1%,IFR质量分数为21%的PP/LGF/IFR/SP阻燃复合材料LOI为29.6%,垂直燃烧等级达到V–0级,热释放速率峰值和总热释放量得到有效降低,热稳定性最好,且燃烧时产生致密的炭层覆盖于玻璃纤维表面,同时加入1%SP后复合材料的力学性能下降幅度相对较小。     

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。     

Influence of thermooxidative aging on the static and dynamic mechanical properties of long‐glass‐fiber‐reinforced polyamide 6 composites

The static and dynamic mechanical properties, thermal behaviors, and morphology of pure long‐glass‐fiber‐reinforced samples [polyamide 6 (PA6)/long glass fiber (LGF)] with different thermal exposure times at 160°C were studied by comparison with stabilized samples in this study. The aging mechanism of the PA6/LGF samples under heat and oxygen was studied with the methods of thermal Fourier transform infrared (FTIR), differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopy (SEM), and so on. The results indicate that the static mechanical strength, melting temperature, and crystallization temperature decreased because of the decomposition of the macromolecular chain of PA6 resin and the debonding of the interface between the glass fibers and matrix. The glass‐transition temperature and crystallinity also increased and decreased, respectively, after aging. The macromolecular chain decomposition dominated in the subsequent aging process; this resulted in many sharp and brittle microcracks appearing on the surfaces of the aged samples, as shown by SEM and the FTIR spectra. The existence of stabilizers endowed the PA6/LGF composites with better retention of static and dynamic mechanical properties. The reason was that the metal ions of the copper salt antioxidant acted as an anti‐aging catalyst in the reinforced PA6 system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39594.     

Utilization of Recycled Polypropylene for Production of Eco-Composites

Renewable raw materials and recyclable thermoplastic polymers provide attractive eco-friendly quality as well as environmental sustainability to the resulting natural fiber reinforced composites. We studied the possibility of using the recycled polypropylene (PP) for production of composites based on kenaf fibers (KF) and rice hulls (RH) as reinforcements. Polypropylene/rice-hulls (PP/RH/CA) and polypropylene/kenaf (PP/K/CA) composites with 30% fiber (filler) content and appropriate compatibilizing agent (CA)—a maleic anhydride grafted PP (MAPP), have been prepared by two steps procedure: melt mixing and compression molding. Flexural strength and thermal stability of the composites with recycled PP were similar to those with neat PP. The composites reinforced with kenaf fibers have shown better properties than those based on rice hulls. The flexural strength of the composite sample with recycled PP is 51.3 MPa in comparison with 51.1 MPa for the composite with neat PP. Degradation temperatures of neat and composite with recycled PP at residual weight 90% are 344.4°C and 343.5°C, respectively. The results obtained report the possibility of utilization of recycled PP for the production of natural reinforcements based composites with good mechanical characteristics for using as construction building materials in housing systems.     

Long jute fiber‐reinforced polypropylene composite: Effects of jute fiber bundle and glass fiber hybridization

Two types of long jute fiber pellet consisting of twisted‐jute yarn (LFT‐JF/PP) and untwisted‐jute yarn (UT‐JF/PP) pellets are used to prepare jute fiber–reinforced polypropylene (JF/PP) composites. The mechanical properties of both long fiber composites are compared with that of re‐pelletized pellet (RP‐JF/PP) of LFT‐JF/PP pellet, which is re‐compounded by extrusion compounding. High stiffness and high impact strength of JF/PP composites are as a result of using long fiber. However, the longer fiber bundle consequently affects the distribution of jute fiber. The incorporation of 10 wt % glass fibers is found to improve mechanical properties of JF/PP composites. Increasing mechanical properties of hybrid composites is dependent on the type of JF/PP pellets, which directly affect the fiber length and fiber orientation of glass fiber within hybrid composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41819.     

Mechanical,thermal, and dynamic mechanical properties of long glass fiber‐reinforced thermoplastic polyurethane/polyoxymethylene composites

Long glass fiber (LGF)‐reinforced thermoplastic polyurethane (TPU) elastomers and polyoxymethylene (POM) (LGF/TPU/POM) composites were prepared by using self‐designed impregnation device. Dynamic mechanical properties of the LGF/TPU/POM composites have been investigated by using dynamic mechanical thermal analysis. The results indicated that the storage modulus and glass transition temperature of the composites increase with increasing the glass fibers content and scanning frequencies. In addition, the Arrhenius relationship has been used to calculate the activation energy of α‐transition of the LGF/TPU/POM composites. The thermal stability of the LGF/TPU/POM composites was investigated by thermogravimetric analysis. The consequence demonstrated that the thermal stability increase with augmenting the content of glass fibers. The mechanical properties of the composites are investigated by a universal testing machine and a ZBC‐4 Impact Pendulum. The results demonstrated the mechanical properties of the composites aggrandize with augmenting the glass fibers content. The good dispersion of the LGFs in the matrix resins is obtained from scanning electron micrographs. POLYM. COMPOS., 35:2067–2073, 2014. © 2014 Society of Plastics Engineers     

High residual mechanical properties at elevated temperatures of bamboo/glass reinforced‐polybenzoxazine hybrid composite

We successfully added bamboo and glass fibers into bisphenol A‐aniline based benzoxazine (BA‐a) resin by hot‐pressing method. In order to improve the interfacial adhesion between bamboo fibers and the matrix, bamboo fibers were pretreated in 6 wt% NaOH solutions for 12 h. The results showed alkali‐treatment had a positive effect on mechanical properties of the composites at both room and elevated temperatures (60°C, 110°C, 160°C, and 210°C). Due to the incorporation of glass fibers, the bamboo/glass reinforced‐polybenzoxazine hybrid composites exhibited highest strength and modulus among all samples and had high residual mechanical properties at elevated temperatures (residual mechanical properties refers to the ratio of strength and modulus of the composites at elevated temperatures to that measured at room temperature). The fractured surface morphologies of the composites were observed by scanning electron microscope. The results showed with the increase of temperature, the debonding and fiber pull‐out became apparent, and the matrix softening could be clearly observed at 210°C. In addition, thermal and thermomechanical properties of neat benzoxazine and the composites were also investigated through thermogravimetric analysis and dynamic mechanical analyzer, respectively. POLYM. ENG. SCI., 59:1818–1829, 2019. © 2019 Society of Plastics Engineers     

长玻璃纤维增强PP/m-PA6复合材料的制备及性能研究

采用熔融拉挤工艺技术制备了长玻璃纤维增强聚丙烯/聚酰胺6[LFT- (PP/m-PA6)]粒料,并研究了材料的界面相互作用情况、力学性能和流变性能。结果表明, m-PA6改善了PP树脂与玻纤之间的润湿性和浸淆性, 提高了界面粘接强度, 使LFT-(PP/m-PA6)的拉伸强度和弯曲强度增加、刚性增强、韧性基本不变; 当长玻纤含量相同时, 以均聚PP（F401）为基质的长玻纤增强聚丙烯（LFT-PP）和LFT-(PP/m-PA6)的力学性能高于以共聚PP（K712）为基质的LFT-PP和LFT-(PP/m-PA6),特别是缺口冲击强度明显提高;在-30 ℃下,LFT-PP（F401）的缺口冲击强度提高了3.91 %,LFT-PP（K712）的缺口冲击强度提高了7.53 %; m-PA6起到了界面润滑作用, 能使LFT-(PP/m-PA6)的流动性能更好。     

Effect of nonionizing radiation on the physicomechanical properties of banana fiber/pp composites with HEMA

Banana fiber‐reinforced polypropylene (PP)‐based unidirectional composites (40% fiber by weight) was manufactured by compression molding. Banana fibers and PP sheets were treated with UV radiation at different intensities and then composites were fabricated. It was found that mechanical properties of irradiated banana fiber and irradiated PP‐based composites were found to increase significantly compared to that of untreated counterparts. Irradiated banana fibers were also treated with 2‐hydroxyethyl methacrylate (HEMA) mixed with methanol (MeOH) under thermal curing method at different temperatures (30–70°C) for different curing times (20–60 min). A series of solutions of different concentrations of HEMA in methanol along with 2% benzyl peroxide were prepared. Monomer concentration, curing temperature and curing time were optimized in terms of polymer loading and mechanical properties. Composites made of 15% HEMA, 50°C and 40 min curing time showed the best mechanical properties than those of untreated composite. Scanning electron microscopy (SEM), water uptake, and simulating weathering test of the composites were also investigated. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation and Mechanical Properties of Long Glass Fiber Reinforced PA6 Composites Prepared by a Novel Process

Summary: Long glass fiber reinforced PA6 (LGF/PA6) prepregs were prepared by impregnating PA6 oligomer melt into reinforcing glass fiber followed by subsequent solid‐state polymerization (SSP) to obtain LGF/PA6 composite pellets. A conventional injection‐molding machine suitable for short glass fiber reinforced composites was applied to the processing of the prepared composites, which reduced the fiber length in the final products. Mechanical properties, thermal property, and fiber length distribution of injection molding bars were investigated. Scanning electron microscopy (SEM) was used to observe the impact fracture surfaces and the surfaces of glass fiber after the SSP. It was found that the LGF/PA6 composites were of favorable mechanical properties, especially the impact strength, although the average length of glass fiber was rather short. By this novel process, the content of glass fiber in composite could be high up to 60 wt.‐% and the maximum level of heat distortion temperature (HDT) was close to the melting temperature of PA6. SEM images indicated the favorable interfacial properties between the glass fiber and matrix. The glass fiber surfaces were further observed by SEM after removing the matrix PA6 with a solvent, the results showed that PA6 macromolecules were grafted onto the surface. Furthermore, the grafting amount of PA6 was increased with SSP time.

SEM images of impact fracture surfaces of LGF/PA6 composites (left) and of glass fiber surfaces after removing PA6 with 5 h SSP (right).     

Annealing effect on crystalline structure and mechanical properties in long glass fiber reinforced polyamide 66

Generally, annealing is one of the important post‐processing methods used to obtain injection molding products coupled with excellent comprehensive performance. Based on a series of experimental studies in this work, a systematic investigation was performed to research the annealing effect on crystalline structure and mechanical properties in long glass fiber reinforced polyamide 66 (LGF‐PA66) composite. The composite was prepared by injection molding, using LGF‐PA66 pellet with 50 wt % fiber content and 12 mm length. Composite samples were annealed in 120 °C to 200 °C range and then subjected to various tests at room temperature. Besides, the releasing strain during a specific temperature cycle was also investigated. Our results suggest that annealing treatment had a neglected impact on the crystallinity and crystal morphology of LGF‐PA66 composite. However, with the increasing of processing temperature, annealing could strikingly promote the phase transition from γ to α and the further growth of α₂ crystal in (010)/(110). In addition, annealing of LGF‐PA66 composite resulted in a drastic increase in tensile and flexural properties and a reduction in impact strength, along with the transition of failure mode. The changes in mechanical properties were attributed to the crystal transition, strengthening of matrix performance, and the release of residual stress. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44832.     

粉末浸渍长玻璃纤维增强聚丙烯的注塑

采用粉末浸渍的方法制备连续玻璃纤维增强聚丙烯预浸料,经切割获得长纤维增强聚丙烯粒子,探索了材料的注塑工艺,研究了注塑后材料的力学性能及其影响因素。结果表明,粉末浸渍的长纤维增强聚丙烯经注塑后可获得力学性能的制品;随着预浸料切割长度的增长、纤维含量的增加,材料的力学性能提高;在基体聚丙烯中添加接枝极性基团的功能化聚丙烯,可改善体系的界面结合,提高材料的力学性能,但功能化聚丙烯的含量超过一定值后,材料的冲击强度有所下降;控制注塑时的模具温度,可以改变材料的一些力学性能。     

长玻纤增强热塑性复合材料阻燃改性及老化性能研究进展

综述了近几年来长玻璃纤维(LGF)增强热塑性复合材料的发展现状,重点以聚丙烯为例,介绍了纤维含量、分布及纤维与基体之间相容性等因素对LGF增强热塑性复合材料性能的影响;重点以尼龙6为例,对LGF增强热塑性复合材料的阻燃改性及老化性能的相关研究进行了阐述。最后对未来LGF增强热塑性复合材料改性及抗老化研究的重点和方向进行了展望。