Simulation of the Interphase of Insert Injection Moldings

In this work, the generalizing of the finite element method(FEM) of thermoplastic prepreg insert injection molding composites was investigated. The specimens were prepared using glass fiber/polyamide 6(GF/PA6) inserted prepreg, and their characteristics were investigated and compared under ANSYS workbench program. The prediction of the bending initial fracture point under analytical tensile testing with interlayer on prepreg insert moldings was focused. It was found that the bending initial fracture point was applied to predict by matching the shear stress. There was obtained from analytical tensile testing and bending analysis. Therefore, it can be obtained the optimum of the elastic modulus ratio on the injection part/interlayer/insert part by using FEM via ANSYS workbench.     

The development of an epoxy resin system for the injection molding of long-fiber epoxy composties

The Combination of reaction injection molding and pultrusion has resulted in a new processing technique, RIM-Pultrusion, Which has been used to produce a thermoplastic epoxy prepreg. This prepreg has been used to produce a long-fiber injection molded phenoxy/carbon fiber composite with near-Zero void content. A heat-activated curing system has been developed, which allows injecton molding of the prepreg to form a thermostet long-finer epoxy/carbon finber composite. The RIM- pultrusion conditions for producing an injection moldable prepreg are described. Capillary rheomety is used to study the epoxy resin to determine the proper molar ratio for RIM-Pultrusion. The long-fiber epoxy compostie is analyzed with dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR). Also., the impact strength and solvent resistance of the long-fiber composite are examined. The properties of the thermoset long-fiber epoxy xomposite are compared to those of a thermoplastic injection molded long-fiber phenoxy composite.     

热处理对EP/CF及EP/CF/GF复合材料力学性能的影响

采用真空辅助树脂转移模塑（VARTM）技术制备了环氧树脂/碳纤维（EP/CF）和环氧树脂/碳纤维/玻璃纤维毡（EP/CF/GF）复合材料。测试了两种纤维铺层方式中树脂流动距离的平方与流动时间的关系,对两种铺层纤维体系的渗透率进行了研究对比;将两种复合材料进行高温处理,并且对其高温处理前后的力学性能进行分析;利用扫描电子显微镜（SEM）观察了复合材料的拉伸断口形貌。结果表明,EP/CF/GF中GF毡的松散结构使树脂更易流动;高温热处理造成了EP/CF弹性模量和拉伸应变的降低,其中弹性模量降低了9.97 %、拉伸应变降低了11.36 %,但对EP/CF/GF的影响较小;GF毡的加入造成了2种复合材料弯曲性能的下降;未经处理的复合材料断口表面光滑,而热处理后的复合材料断口表面粗糙且有大量基体附着。     

Recyclability of a continuous e-glass fiber reinforced polycarbonate composite

Fiber reinforced plastics are multi-component materials for which physical properties are strongly dependent on fiber and resin structure. Despite the disruptive nature of recycling methods on such structures, these materials nevertheless can be recycled. In this report, the recyclability of a fiber-reinforced cyclic BPA polycarbonate has been studied. It is found that ground up composite is recyclable and possesses properties as good as or better than a comparable commercial composite. The processing techniques investigated herein are injection, extrusion compression, and compression molding. As expected, processing technique and parameters are important in determining the mechanical properties of the molded regrind. Our results show that injection and extrusion compression molding yield recycled composites with good tensile properties, though the impact strengths are relatively low. This is due to high fiber orientation and fiber bundle dispersion. On the other hand, compression molded samples, which show random fiber orientation and low fiber bundles dispersion have relatively low tensile properties, but excellent impact strength. Results are discussed in terms of microstructural details, which include resin molecular weight and fiber length and orientation.     

成型工艺对碳纤维增强热塑性聚酰亚胺复合材料性能的影响

采用双螺杆挤出共混的方法,制备了热塑性聚酰亚胺(TPI)/碳纤维(CF)复合材料,考察了注射和热模压两种成型工艺对 TPI/CF 复合材料力学性能、应力-应变曲线、线性膨胀系数以及摩擦磨损性能的影响。结果表明,注射成型试样的各项力学性能均比模压成型的高,达到1.5～2.0倍;相比模压成型,注射成型试样具有较高的断裂强度和断裂伸长率,其应力-应变曲线斜率也较大;由于纤维在注射流动方向上高度取向,注射成型试样具有最佳的高温尺寸稳定性;注射成型试样的摩擦系数和磨损率为模压成型的1.7倍和1.5倍;扫描电镜分析表明,纤维在注射流动方向上高度取向,模压成型试样呈现黏着磨损,注射成型试样以磨粒磨损为主。     

Improved through‐plane electrical conductivity in a carbon‐filled thermoplastic via foaming

Flow‐induced orientation of the conductive fillers in injection molding creates parts with anisotropic electrical conductivity where through‐plane conductivity is several orders of magnitude lower than in‐plane conductivity. This article provides insight into a novel processing method using a chemical blowing agent to manipulate carbon fiber (CF) orientation within a polymer matrix during injection molding. The study used a fractional factorial experimental design to identify the important processing factors for improving the through‐plane electrical conductivity of plates molded from a carbon‐filled cyclic olefin copolymer (COC) containing 10 vol% CF and 2 vol% carbon black. The molded COC plates were analyzed for fiber orientation, morphology, and electrical conductivity. With increasing porosity in the molded foam part, it was found that greater out‐of‐plane fiber orientation and higher electrical conductivity could be achieved. Maximum conductivity and fiber reorientation in the through‐plane direction occurred at lower injection flow rate and higher melt temperature. These process conditions correspond with foam flow during filling of the mold cavity, indicating the importance of shear stress on the effectiveness of a fiber being rotated out‐of‐plane during injection molding. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Effect of packing pressure on fiber orientation in injection molding of fiber‐reinforced thermoplastics

Injection molding of fiber‐reinforced polymeric composites is increasing with demands of geometrically complex products possessing superior mechanical properties of high specific strength, high specific stiffness, and high impact resistance. Complex state of fiber orientation exists in injection molding of short fiber reinforced polymers. The orientation of fibers vary significantly across the thickness of injection‐molded part and can become a key feature of the finished product. Improving the mechanical properties of molded parts by managing the orientation of fibers during the process of injection molding is the basic motivation of this study. As a first step in this direction, the present results reveal the importance of packing pressure in orienting the fibers. In this study, the effects of pressure distribution and viscosity of a compressible polymeric composite melt on the state of fiber orientation after complete filling of a cavity is considered experimentally and compared with the simulation results of Moldflow analysis. POLYM. COMPOS. 28:214–223, 2007. © 2007 Society of Plastics Engineers     

PA6/GF复合材料注射成型模拟流动分析

采用模拟流动分析软件MPI，借助有限元分析方法对玻璃纤维增强尼龙6（PA6／GF）复合材料的注射成型过程进行了模拟流动分析，研究了PA6／GF复合材料制品的纤维取向对最终力学性能的影响，获得了可满足实际设计要求的模具浇注和冷却系统布置、注塑机锁模力曲线和推荐的螺杆速度曲线等参数，对于缩短PA6／GF复合材料注射成型设计周期、提高制品质量具有重要的指导意义。     

Visualization analysis of reciprocating‐screw plastication process of glass fiber‐reinforced resins in a glass‐inserted heating cylinder

One challenge in injection molding of long fiber‐reinforced resins is minimizing the fiber breakage during resin plastication and resin flow into a mold. Such fiber breakage reduces the strength of the molded product. Reciprocating plastication is subjected to periodic positional fluctuations of the screw and cylinder in the molding cycle. In this study, visualization experiments were conducted on the reciprocating plastication of long glass fiber (GF)‐reinforced polypropylene with 50 wt% GF. It was found that: (1) temporary voids form in the resin during the metering process, and the pellets rotate from an orthogonal to parallel orientation in the flight direction; (2) length of the weight‐averaged fiber temporarily decreased in the middle stage of the injection process; (3) length of the weight‐averaged fiber was most strongly influenced by the waiting time; and (4) for constant waiting time, the fiber breakage could be minimized by lowering the rotation speed, lowering the back pressure, and shortening the charge stroke. POLYM. ENG. SCI., 59:846–853, 2019. © 2018 Society of Plastics Engineers     

Studies on mechanical properties of sisal fiber/phenol formaldehyde resin in‐situ composites

Phenol formaldehyde resin (PF) reinforced with short sisal fibers (SF) were obtained by two methods, direct‐mixing and polymerization filling. Impact and bending properties of resulting composites were compared. Under the same compression molding conditions, polymerization filled composites showed better mechanical properties than those of direct‐mixed composites. The influences of fiber modifications on the mechanical properties of SF/PF in‐situ (polymerization filled) composites have been investigated. Treated‐SF‐reinforced composites have better mechanical properties than those of untreated‐SF‐reinforced composites. The effects of SF on water absorption tendencies of SF/PF composites have also been studied. In addition, sisal/glass (SF/GF) hybrid PF composites of alkali‐treated SF were prepared. Scanning electron microscopic studies were carried out to study the fiber‐matrix adhesion. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Morphology and mechanical properties of injection‐molded ultrahigh molecular weight polyethylene/polypropylene blends and comparison with compression molding

The mechanical properties and morphology of UHMWPE/PP(80/20) blend molded by injection and compression‐molding were investigated comparatively. The results showed that the injection‐molded part had obviously higher Young's modulus and yield strength, and much lower elongation at break and impact strength, than compression‐molded one. A skin‐core structure was formed during injection molding in which UHMWPE particles elongated highly in the skin and the orientation was much weakened in the core. In the compression‐molded part, the phase morphology was isotropic from the skin to the core section. The difference in consolidation degree between two molded parts that the compression molded part consolidated better than the injection one was also clearly shown. In addition, compositional analysis revealed that there was more PP in the skin than core for the injection‐molded part, whereas opposite case occurred to the compression‐molded one. All these factors together accounted for the different behavior in mechanical properties for two molded parts. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

玻纤增强ABS复合材料的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及玻璃纤维(GF)为原料,以环氧树脂作为界面相容剂,研究了界面相容剂对玻璃纤维增强ABS复合材料力学性能及界面粘接的影响.结果表明:加入环氧树脂,玻纤增强ABS复合材料的力学性能明显提高;随着玻纤质量分数的增加,复合材料的拉伸强度、弯曲强度、冲击强度均逐渐增加;玻纤质量分数为30%时,GF/ABS/环氧树脂复合材料的拉伸强度比未改性的复合材料的拉伸强度提高了30%,弯曲强度提高了25%,冲击强度也提高了50%.     

聚合物基纤维纳米复合材料研究

以纳米粒子ＳｉＯ２－ｘ、高强玻璃纤维（Ｓ－ＧＦ）作为增强材料,分别以环氧树脂ＣＹＤ－１２８和４,４－二氨基二苯基砜（Ｄ－ＤＳ）作为基体中制备了聚合物基纤维纳米复合材料,测试了预浸料及复合材料的性能。结果表明,Ｓ－ＧＦ、ＳｉＯ２＝ｘ／ＣＹＤ＝１２８／ＤＤＳ与Ｓ－ＧＦ／ＣＹＤ－１２８／ＤＤＳ两种体系预浸料性能相似,但ＳｉＯ２－ｘ纳米粒子的加入,使复合材料的各项性能提高。     

动态注射成型短玻纤增强高密度聚乙烯力学性能的研究

在不同的振动条件下注射成型短玻纤增强高密度聚乙烯复合材料。实验表明,振动可以有效地改善玻纤在树脂基体中的分散取向状况,提高复合材料的力学性能。与稳态注射成型的复合材料相比,动态注射成型复合材料的拉伸强度最大可提高11.1%,冲击强度最大可提高11.4%。     

Mechanical properties of glass fiber reinforced polypropylene injection molded with a rotation mold

A special mold (Rotation, Compression, and Expansion Mold) was used to impose a controlled shear action during injection molding of short glass fiber reinforced polypropylene discs. This was achieved by superimposing an external rotation to the pressure‐driven advancing flow front during the mold filling stage. Central gated discs were molded with different cavity rotation velocities, inducing distinct levels of fiber orientation through the thickness. The mechanical behavior of the moldings was assessed, in tensile and flexural modes on specimens cut at different locations along the flow path. Complete discs were also tested in four‐point flexural and in impact tests. The respective results are analyzed and discussed in terms of relationships between the developed fiber orientation level and the mechanical properties. The experimental results confirm that mechanical properties of the moldings depend strongly on fiber orientation and can thus be tailored by the imposed rotation during molding. POLYM. ENG. SCI. 46:1598–1607, 2006. © 2006 Society of Plastics Engineers.     

流动场下含β成核剂的玻璃纤维增强聚丙烯复合材料结构与性能研究

采用普通注射成型和动态保压注射成型分别制备了不同玻璃纤维（GF）含量和β成核剂含量的等规聚丙烯（iPP）复合材料,测试了复合材料的力学性能,并采用二维广角X射线衍射、扫描电子显微镜和二维小角X射线散射研究了复合材料的iPP分子链取向、GF取向及结晶性能。结果表明,在动态保压注射成型条件下,GF含量为30 %（质量分数,下同）、β成核剂含量为0.2 %时,复合材料具有最优异的综合性能,拉伸强度为58.52 MPa,冲击强度为9.26 kJ/m2,这是由于在流动场下含GF与β成核剂的复合材料形成了"皮刚芯韧"类竹子的仿生结构。     

Hierarchic structure and mechanical property of glass fiber reinforced isotactic polypropylene composites molded by multiflow vibration injection molding

Maleic anhydride‐grafted polypropylene (Ma‐PP) and β nucleation agents (β‐NA) were used to modify the glass fiber (GF)/isotactic polypropylene (iPP) composite. The interface adhesion, degree of orientation, and crystalline morphologies of the PP/GF composites molded by multiflow vibrate‐injection molding (MFVIM) and conventional injection molding (CIM) were studied by polarized light microscopy (PLM), scanning electronic microscopy (SEM), and X‐ray measurements. Results prove that the interface adhesion was improved by the Ma‐PP; γ crystal was generated by the MFVIM due to the instant high pressure and shear during the multiflow; and a hierarchical structure which has a strengthened skin and a toughened core was formed. As a result, the final PP/GF/β‐NA composite has a 60% increase in tensile strength and 80% improvement in impact strength compare with the CIM pure PP/GF composite. Based on the observations, a modified model is proposed to interpret the strengthening and toughening mechanism. Our work paves the way to obtain high‐performance GF/iPP composites. POLYM. COMPOS., 38:2707–2717, 2017. © 2015 Society of Plastics Engineers     

Properties enhancement of short glass fiber‐reinforced thermoplastics via sandwich injection molding

This article demonstrates using sandwich injection molding in order to improve the mechanical properties of short glass fiber‐reinforced thermoplastic parts by investigating the effect of fiber orientation, phase separation, and fiber attrition compared to conventional injection molding. In the present case, the effect of short glass fiber content (varying from 0–40 wt%) within the skin and core materials were studied. The results show that the mechanical properties strongly depend not only on the fiber concentration, but also on the fiber orientation and the fiber length distribution inside the injection‐molded part. Slight discrepancies in the findings can be assumed to be due to fiber breakage occurring during the mode of processing. POLYM. COMPOS., 26:823–831, 2005. © 2005 Society of Plastics Engineers     

The effect of ambient moisture and temperature conditions on the mechanical properties of glass fiber/carbon fiber/nylon 6 sandwich hybrid composites consisting of skin‐core morphologies

The concept of skin‐core (SC) morphology was used to make sandwich hybrid composites in which the skin and core were composed of different fibers in the same matrix. The sandwich blends comprising glass skin with carbon core and vice versa were compared with those of the hybrid composite, while the respective carbon (CF) and glass fiber (GF) composites served as points of reference. The composites were compounded and fabricated into injection molded tensile specimens and 3‐mm thick plaques. The effect of ambient temperature and moisture was studied. The fracture mechanical characterization of the various materials was done by using notched compact tension (CT) specimens. Tensile properties were also used to characterize the composites. Morphogical studies based on scanning electron microscopy and light microscopy were used to elucidate fracture characteristics. Deterioration of properties was noticed under hot and humid conditions. Synergism in flexural properties was observed in the CF/GF/PA hybrid composite. The mechanical properties of the CF/GF/PA hybrid are closer to those of CF/PA, suggesting a cost advantage by substituting half of the carbon fibers with glass fibers. Dynamic mechanical analysis results revealed that synergism in T_g is attained by blending or sandwiching glass and carbon fibers. Morphological studies reaffirmed the skin‐core morphology of the composites. POLYM. COMPOS., 26:52–59, 2005. © 2004 Society of Plastics Engineers.     

Microstructure and fracture behavior of (co)injection‐molded polyamide 6 composites with short glass/carbon fiber hybrid reinforcement

The mechanical and fracture properties of injection molded short glass fiber)/short carbon fiber reinforced polyamide 6 (PA 6) hybrid composites were studied. The short fiber composites of PA 6 glass fiber, carbon fiber, and the hybrid blend were injection molded using a conventional machine whereas the two types of sandwich skin–core hybrids were coinjection molded. The fiber volume fraction for all formulations was fixed at 0.07. The overall composite density, volume, and weight fraction for each formulation was calculated after composite pyrolysis in a furnace at 600°C under nitrogen atmosphere. The tensile, flexural, and single‐edge notch‐bending tests were performed on all formulations. Microstructural characterizations involved the determination of thermal properties, skin–core thickness, and fiber length distributions. The carbon fiber/PA 6 (CF/PA 6) formulation exhibits the highest values for most tests. The sandwich skin‐core hybrid composites exhibit values lower than the CF/PA 6 and hybrid composite blends for the mechanical and fracture tests. The behaviors of all composite formulations are explained in terms of mechanical and fracture properties and its proportion to the composite strength, fiber orientation, interfacial bonding between fibers and matrix, nucleating ability of carbon fibers, and the effects of the skin and core structures. Failure mechanisms of both the matrix and the composites, assessed by fractographic studies in a scanning electron microscope, are discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 957–967, 2005