Impact behavior of aramid fiber/glass fiber hybrid composites: The effect of stacking sequence

Aramid fiber/glass fiber hybrid composites were prepared to examine the effect of stacking sequence on the impact behavior of thin laminates. The effect of position of the aramid layer on the impact properties of hybrid composites was investigated using driven dart impact tester. The delamination area and fracture surface of hybrid composites were analyzed for correlation with impact energy. The addition of glass layer to aramid layer reduced the impact resistance of hybrid composite due to the restriction in the deformation of aramid layer. The position of aramid layer resulted in variations in the impact behavior of hybrid composites. When the aramid layer was at the impacted surface, the composite exhibited a higher impact energy. This was attributed to the fact that the flexible layer at the impacted surface in thin laminates can experience larger deformation. In three‐layer composites, the aramid fiber‐reinforced composite ( AAA ) exhibited the highest total impact energy due to high impact energy per delamination area (1EDA) in spite of low delamination area. Aramid fiber and glass fiber‐reinforced composites showed a different impact behavior according to the change of thickness. This was attributed to the difference in the energy absorption at interface between laminae.     

Effect of laminate geometry on impact performance of aramid fiber/polyethylene fiber hybrid composites

ABSTRACT One‐layer and two‐layer hybrid composites were fabricated using open leaky mold method in order to examine the effect of structural geometry on impact performance of aramid fiber/polyethylene (PE) fiber hybrid composites. The impact property of interply hybrid composites was compared with that of intraply hybrid composites with respect to impact mechanism and deformation extent. In addition, the delamination area of two hybrid composites was considered for correlation with impact properties. In one‐layer composites, two intraply hybrids exhibited the different characteristics in impact mechanism and deformation shape. The laminate T absorbed most of impact energy through large deformation of PE fibers with an elliptical damage shape. On the other hand, the laminate R showed the higher impact energy because both aramid and PE fibers contributed to the absorption of impact energy with a round damage zone. In case of two‐layer composites, interply hybrid composites exhibited higher impact energy than intraply hybrid composites. The interply hybrids absorbed the impact energy through deformation process such as fiber pullout and delamination, and impact energy was well correlated to delamination area. The impact energy of intraply hybrid composites was primarily dominated by full exertion of deformation in PE fiber rather than delamination process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 952–959, 2000     

表面处理对玻纤/碳纤增强橡胶基密封复合材料性能的影响

采用压延成张工艺制备碳纤维和玻璃纤维混杂增强非石棉橡胶基密封复合材料(NAFC),以横向抗拉强度作为表征混杂增强橡胶基密封材料中纤维与橡胶界面粘结性能的指标.通过扫描电镜(SEM)对材料横向拉伸试样断口进行形貌分析,及对材料的耐油、耐酸、耐碱性能进行测试,探讨了不同表面处理工艺对纤维与基体界面粘结效果的影响.研究结果表明,对玻璃纤维采用偶联剂KH-550浸渍后涂覆环氧树脂涂层,对碳纤维在空气氧化后涂覆环氧树脂涂层,可有效增强纤维、基体的界面粘结,所制得的混杂纤维增强复合材料具有较好的机械性能和耐介质性能.     

Effect of compressive loading speed and stacking sequence on mechanical characteristics of satin weave E‐glass/epoxy composites

This article experimentally investigated the in‐plane loading speed dependent mechanical properties and failure modes of satin weave E‐glass/epoxy composite laminates [45/−45/0/90]_ns. Two types of E‐glass fabric/epoxy pre‐impregnated tapes were used to manufacture the composite laminates specimens. The low strain rate tests were conducted with an INSTRON™ testing machine, and the high strain rate tests done using a pulse shape modified compressive Split Hopkinson Pressure Bar apparatus. From the experimental result, it was concluded that under different strain rate loading, compressive strength, modulus, and strain at peak stress were rate sensitive. Optical and microscopic photos of the specimens were taken to determine operative failure modes. Within the studied strain rate regimes, the failure mode changed from splitting followed by fiber kink buckling to predominantly delamination and shear fracture as strain rate increases from quasi‐static to high strain rates. Compressive properties and failure modes were severely affected by strain rate, stacking sequence, and fabric material. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

Mechanical and high velocity impact performance of a hybrid long carbon/glass fiber/polypropylene thermoplastic composite

This research explores mechanical and high velocity impact response of hybrid long carbon/glass fiber-reinforced polypropylene thermoplastic composites (HLFT) with different fiber lengths. The work examines three hybrid long fiber thermoplastic composites, i.e., 5, 10 and 20 mm. The HLFTs were prepared by a combination of extrusion and pultrusion processes and using a cross-head die. Tensile and Izod impact tests were carried out to evaluate the mechanical performance of each HLFT compound. A gas gun with a spherical projectile was used to conduct high velocity impact tests at three velocities of 144, 205 and 240 m/s. The results showed that internal mixing operation caused extensive reduction in fiber length of all three LFT lengths. Tensile strength, modulus and Izod impact test results were the indications of higher values with increase in HLFT length. Comparison of these results for the HLFT with that of corresponding glass/PP LFTs, adopted from earlier work by Shayan Asenjan et al. (J Compos Mater 53:353–360, 2019), showed better performance of HLFT. The high velocity impact results showed a steady higher impact performance with the increase in HFLT fiber length for all impact velocities tested. Comparison of HLFT high velocity impact performance revealed better results for all impact velocities tested with that of the corresponding glass/PP LFT composite.     

芳纶纤维表面的络合改性及其天然橡胶复合材料性能的研究

利用合适的溶剂配制成的氯化钙溶液浸渍活化芳纶纤维表面.通过均匀设计实验,研究了氯化钙溶液质量分数及处理时间对芳纶纤维天然橡胶复合材料力学性能的影响.实验结果表明:利用氯化钙甲醇溶液浸渍芳纶纤维,再用甲醇清洗芳纶纤维是降低纤维表面结晶度和提高表面粗糙度的最佳方法,溶液中氯化钙质量分数为2％时,复合材料获得最大300％定伸应力及撕裂强度,处理时间在实验参数范围内对这2种力学性能几乎没有影响.     

Effect of stacking sequence on mechanical properties of hybrid flax/jute fibers reinforced thermoplastic composites

In this study, the hybrid composites were prepared by stacking jute/PP nonwoven and flax/MAPP woven fabrics in defined sequences. Polypropylene (PP) and maleic anhydride grafted polypropylene (MAPP) were used as matrix materials. Jute and flax fibers were treated with alkali solution in order to improve the interface properties of the resultant composites. The mechanical properties of these hybrid composites were analyzed by means of tensile, flexural, and drop‐weight impact tests. The effect of fabric stacking sequence on the mechanical properties of the composites was investigated. The stacking of nonwovens at the top and in alternate layers has resulted in maximum flexural strength, flexural stiffness, and impact force. It was also shown that hybrid composites have improved tensile, flexural, and impact properties in comparison to neat PP matrix. POLYM. COMPOS., 36:2167–2173, 2015. © 2014 Society of Plastics Engineers     

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.     

Preparation of polypropylene/glass fiber composite with high performance through interfacial crystallization

This paper reported an approach to improve the interaction between glass fiber (GF) and polypropylene (PP) through interfacial crystallization. The experimental results showed that polar nucleating agents had strong interaction with GF and tended to deposit on the surface of GF through the dip‐coating method. Since the nucleating agents had good lattice matching with PP, the modified GF could promote the interfacial crystallization of PP to increase the interfacial interaction between GF and PP and improve the performance of PP/GF composites. However, at high processing temperature, the nucleating agents dissolved into the polymer melts, and the nucleation on the GF surface for PP crystallization decreased, impairing the interface compatibility and the final performance of the PP/GF composites. J. VINYL ADDIT. TECHNOL., 23:284–289, 2017. © 2015 Society of Plastics Engineers     

Effect of stacking sequence on failure mode of fiber metal laminates under low-velocity impact

In this study, the effect of stacking sequence on the impact behavior of fiber metal laminates under the drop weight impact test was investigated. Four groups of specimens with layups of [Al-(0/90)₈-Al], [Al-(±45)₈-Al], [Al-(0/90)₄-(±45)₄-Al] and [Al-(±45)₄-(0/90)₄-Al] were fabricated and tested. Fiberglass–aluminum composite specimens were made of Al 2024-O sheets and woven glass fabrics with epoxy resin. These specimens were tested using a drop weight impact testing machine with an energy of 44.13 J and speed of 3.43 m/s. The results obtained showed a higher load-bearing capacity before failure of the outer aluminum layer for specimens with [Al-(±45)₈-Al] layups. Fiber metal laminates with [Al-(0/90)₈-Al], [Al-(0/90)₄-(±45)₄-Al] and [Al-(±45)₄-(0/90)₄-Al] layups had lower load-bearing capacities than the first group of specimens, respectively. The form of damage progression in the second layer of aluminum of specimens was completely dependent on the stacking sequence of composite layers. Numerical modeling of the drop weight impact test was carried out using ABAQUS 6.9 software. A detailed analysis of the failure mechanisms in the aluminum layer has been presented. A comparison between experimental results and the numerical simulation was performed to verify the simulation procedure.     

碳纤维/玄武岩纤维/聚丙烯复合材料力学性能的研究

以碳纤维(CF)、玄武岩纤维(BF)、聚丙烯(PP)为原料,再与增容剂、抗氧剂混合制备改性PP粒料.讨论了 CF/BF复合纤维含量、CF与BF的配比、增容剂用量、抗氧剂用量、纤维添加方式对复合材料力学性能的影响.结果表明:CF/BF/PP复合材料中复合纤维的质量分数以20％～30％为宜;复合纤维中CF含量的增加能提高复...     

Nonisothermal crystallization behavior of LLDPE/glass fiber composite

The nonisothermal crystallization behavior of linear low-density polyethylene (LLDPE)/glass fiber (GF) composite was investigated by differential scanning calorimetry (DSC). It was observed that the crystallization temperature peak (T_p) of LLDPE composite containing 5.0 wt % GF (LLDPE/GF5) was higher than that of the pure LLDPE at various cooling rates. The half-time of crystallization (t_1/2) of LLDPE/GF5 composite was shortened under the effect of GF. The nonisothermal crystallization kinetics of LLDPE and LLDPE/GF5 composite were analyzed through the Avrami, Ozawa, and Mo equations. The results indicated that the data of the nonisothermal crystallization for LLDPE and LLDPE/GF5 composite calculated based on the Ozawa equation did not have the good linear relationship, but the nonisothermal crystallization behaviors of LLDPE and LLDPE/GF5 composite could be successfully described by the modified Avrami and Mo methods. The crystallization rate Z_c of the modified Avrami parameter of LLDPE/GF5 composite was higher than that of pure LLDPE at the same cooling rate. The Mo parameter F(T) of LLDPE/GF5 composite was lower than that of LLDPE at the same degree of crystallinity. Through the Kissinger equation, the activation energies E_d of LLDPE and LLDPE/GF5 composite were evaluated, and their values were 312.3 and 251.2 kJ/mol, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

玻璃纤维/聚氯乙烯复合材料的制备与性能研究

采用注塑成型法制备了玻璃纤维/PVC(聚氯乙烯)复合材料。研究了制备过程中成型压力、成型温度及模具温度等对该复合材料拉伸强度、剪切强度和弯曲强度的影响。研究结果表明:当成型射压为130 MPa、保压为100 MPa、背压为0.5 MPa、成型温度为420℃、模具温度为100℃和w(玻璃纤维)=15%(相对于复合材料质量而言)时,复合材料的综合性能相对最好,其拉伸强度(77.4 MPa)和剪切强度(57.4 MPa)相对最大,并且制品表面光滑且颜色正常,而且弯曲强度比纯PVC提高了68.4%。     

Effect of glass fiber surface treatment on the mechanical strength of glass fiber reinforced resin mineral composite for machine tool bed

With excellent vibration alleviating properties, resin mineral composite (RMC) has attracted special attention in the field of mechanical engineering. However, applications of RMC are restricted because of its limited mechanical strength. In this research, the glass fiber (GF) was added into RMC to increase its mechanical strength, and the effect of the length and mass fraction of GF on the mechanical strength of GF/RMC were investigated. Results showed that the compressive strength and flexural strength of RMC first increased and then decreased as the length and mass fraction of GF increased. In order to improve the interfacial bonding between GF and RMC, the GF was subsequently treated by ultrasonication, oxidation, and silanization. And three types of treated GF, i.e., ultrasonic treated GF (U‐GF), ultrasonic and oxidation treated GF (O‐GF), and ultrasonic, oxidation and silanization treated GF (S‐GF) were obtained. Among these three types of treated GF, the S‐GF exhibited superior reinforcement in RMC. In addition, the effect of oxidation parameters on the mechanical strength of S‐GF/RMC was investigated. In the case of sodium hydroxide oxidation, the optimum mechanical strength of S‐GF/RMC was achieved when the S‐GF was treated in 1.5 mol/L sodium hydroxide for 3 h at 40°C, in which the compressive strength and flexural strength of S‐GF/RMC increase by 17.5% and 20.8% compared to neat RMC, respectively. In the case of hydrogen nitrate oxidation, the best mechanical strength of S‐GF/RMC was achieved when the S‐GF was treated in 1.5 mol/L hydrogen nitrate for 5 h at 80°C, in which the compressive strength and flexural strength of S‐GF/RMC increased by 11.2% and 18.1% compared to neat RMC, respectively. POLYM. COMPOS., 38:1559–1570, 2017. © 2015 Society of Plastics Engineers     

Mode II interlaminar fracture behavior of carbon bead‐filled epoxy/glass fiber hybrid composite

To investigate the effect of including carbon beads on the mechanical properties of epoxy resin, the fracture toughness of carbon bead‐filled epoxy was earlier evaluated using a CT (compact tension) specimens and Mode I fracture toughness was observed. Based on those results, in this study, the Mode II interlaminar fracture toughness of carbon bead filled epoxy/glass fiber hybrid composites was evaluated using end notch flexure (ENF) specimens. The hybrid composites showed increased Mode II interlaminar fracture toughness. The optimal bead volume fraction was around 15%.     

Effect of thermoplastic veils on interlaminar fracture toughness of a glass fiber/vinyl ester composite

The effects of two thermoplastic micro‐veils, polyamide (PA) and polyethylene terephthalate (PET) veil, on the interlaminar fracture toughness of a glass fiber/vinyl ester (GF/VE) composite were investigated. The veils incorporated into the composite as interleaving materials were first characterized via scanning electron microscopy (SEM), differential scanning calorimetry (DSC), contact angle and tensile testing in order determine the best candidate as toughening agent for the GF/VE composite. Composite laminates were manufactured by vacuum‐assisted resin infusion process. Double cantilever beam (DCB) testing was performed to investigate the Mode I type interlaminar fracture toughness of the composites, which was characterized by critical strain energy release rate (G _IC). An increased G _IC was obtained by incorporating the PA veil, but it changed negligibly by the addition of the PET veil. The analysis of the composites fracture surface via SEM revealed increased fiber bridging between adjacent plies in the case of PA veil interleaved composites which played a key role in enhancing the Mode I interlaminar fracture toughness. However, the PET veil present in the interlaminar region did not take part in any energy absorbing mechanism during the delamination, thus keeping the G _IC of the composite unaltered. POLYM. COMPOS., 38:2501–2508, 2017. © 2015 Society of Plastics Engineers     

乙二胺对芳纶纤维化学镀银的影响

采用乙二胺作辅助配位剂在芳纶纤维上化学镀银,制备镀银导电Kevlar(凯夫拉)芳纶纤维.分别采用分析天平、扫描电镜(SEM)、X射线衍射(XRD)和万用表,研究了乙二胺对化学镀银层的增重率、表面形貌、晶体结构和表面电阻的影响,并探讨了化学镀银层的生长过程.结果表明,加入乙二胺后,镀液稳定性增强,纤维增重率提高到50%左...     

HTBN/PTMG软段共混聚氨酯/芳纶浆粕纤维复合材料的制备与性能研究

以端羟基聚丁二烯-丙烯腈共聚物（HTBN）、聚四氢呋喃醚二醇（PTMG）、甲苯二异氰酸酯（TDI）、扩链剂3,5-二甲硫基甲苯二胺（DMTDA）为原料,芳纶浆粕纤维为填料制备聚氨酯脲（PUU）弹性体,并对其结构、性能进行了研究。结果表明：随着PTMG含量的增加,拉伸强度不断增加,撕裂强度先降低后升高;PTMG的加入使材料的耐温性提高,玻璃化转变温度（Tg）降低。