Processing and mechanical properties of hydroxyapatite–polysulfone laminated composites

Designing biocomposites that mimic bone with specific mechanical properties of toughness and elastic modulus is a long-standing challenge in the biomaterials field. Traditional biocomposites comprise polymer matrices reinforced with ceramic particles. Laminated composites are structures also found in nature that can offer improved mechanical properties such as strength, elastic modulus and toughness. Hydroxyapatite/polysulfone laminated composites were fabricated to develop biologically compatible, toughened composites that would match the elastic modulus of bone. Multilayered composites were successfully designed with improved toughness measured by the work of fracture. Toughness measurements were more than an order of magnitude greater than monolithic hydroxyapatite. The toughness and modulus values of hydroxyapatite/polysulfone were within the range of cortical bone.     

Homogenized Finite Element Analysis on Effective Elastoplastic Mechanical Behaviors of Composite with Imperfect Interfaces

A three-dimensional (3D) representative volume element (RVE) model was developed for analyzing effective mechanical behavior of fiber-reinforced ceramic matrix composites with imperfect interfaces. In the model, the fiber is assumed to be perfectly elastic until its tensile strength, and the ceramic material is modeled by an elasto-plastic Drucker-Prager constitutive law. The RVE model is then used to study the elastic properties and the tensile strength of composites with imperfect interfaces and validated through experiments. The imperfect interfaces between the fiber and the matrix are taken into account by introducing some cohesive contact surfaces. The influences of the interface on the elastic constants and the tensile strengths are examined through these interface models.     

Highly efficient preparation of multi-angle continuous carbon fibre reinforced hydroxyapatite composites by electrostatic splitting method

An electrostatic splitting device was self-designed and manufactured for highly efficient preparation of multi-angle continuous carbon fibre (CF)-reinforced ceramic-based composites and was used to prepare multi-angle continuous CF and nano-hydroxyapatite (nHA)-coated CF reinforced HA composites with improved CF dispersion and content. The compressive strength of sintered [0°/90°] CF reinforced hydroxyapatite (CF/HA) composites is more than two and a half times that of hydroxyapatite and is superior to that of cortical bone (26.42–110.7%). Compared with hydroxyapatite, fracture toughness of [0°/0°], [0°/90°] and [? 45°/+ 45°] CF/HA composites increase by 28.83%, 66.32% and 115.95%, respectively. The strength and fracture toughness (30.2 MPa·m^1/2) of [? 45°/+ 45°] CF/HA bioceramics display synchronously improving. Micromechanical property and crack propagation process of the composites were simulated in depth. Based on optimised dispersion and arrangement of CF, the introduction of nHA coating enhances the mechanical properties of nHA-coated CF reinforced HA composites because nHA coating can block the generation and propagation of cracks.     

Synthesis and properties of HA/ZnO/CNT nanocomposite

The goal of this study was to examine the tribomechanical properties of hydroxyapatite (HA)/ZnO and HA/ZnO/CNT composite ceramics (carbon nanotubes; with different ratios 0.5?wt%, 1.0?wt%, and 1.5?wt%). The composites were synthesized using the hydrothermal method in an autoclave. The structure and morphology of the composites were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The consolidation process was performed by sintering the compounds at 1150?°C under an argon gas atmosphere. The effects of ZnO and CNT on the mechanical properties and wear resistance of the HA-nanoparticle-based ceramic composites were investigated using a Vickers hardness tester, nanoindentation, and reciprocating wear tester equipment. The nanohardness and elastic modulus of the sintered samples increased and the friction coefficient of the sintered samples decreased as the fraction of CNTs increased compared to the pure HA and HA/ZnO compounds. Furthermore, the wear loss of HA/ZnO/CNT composites decreased with the increase in the CNT content compared to the HA and HA/ZnO samples.     

承载/声隐身混杂纤维复合材料的研究

通过试验获取了碳纤维(CF)、凯夫拉纤维(KF)、玻璃纤维(GF)、超高分子量聚乙烯纤维(UHMPEF)复合材料的力学性能和声学性能参数,在此基础上分别利用等效刚度法和传递矩阵法,对CF/UHMPEF、CF/KF、CF/GF混杂纤维复合材料的拉伸刚度、声反射系数和声透射系数进行计算。结果表明,材料的刚度和强度基本相同的条件下CF/UHMPEF复合材料声压反射系数最小,其次是CF/KF复合材料,再次是CF/GF复合材料。10kHz频率范围内3种混杂材料的声透射系数都达到95%以上。     

Surface organo-modification of hydroxyapatites to improve PLA/HA compatibility

Polylactide/hydroxyapatite (PLA/HA) composites are promising tissue engineering materials because of the PLA biodegradability and HA as a natural bone component. PLA/HA composites without HA modification lead to mechanical failure due to the interfacial immiscibility. In this study, an effective chemical surface methodology is used to modify HA to obtain PLA/HA composites with superior mechanical properties. The HA particles are modified with fatty acids (adipic, sebacic, lauric, and linoleic) and incorporated into a PLA matrix by polymer solution casting, using chloroform as the solvent. After the HA modification, the films exhibited an improvement in tensile strength, elongation at break, and elastic modulus. Yet, the best results observed are by sebacic and adipic acid modification. These increments are attributed to a higher affinity of the organo-modified HA particles within the PLA matrix. Therefore, the development of materials for osteo-regeneration engineering based on these systems is quite promising.     

碳纤维改性HA/PMMA生物复合材料力学性能的研究

采用原位合成与溶液共混相结合的方法,制备了短切碳纤维增强纳米羟基磷灰石(HA)/聚甲基丙烯酸甲酯(PMMA)生物复合材料。研究了碳纤维的含量和长度对HA/PMMA复合材料结构和力学性能的影响。采用万能材料试验机和扫描电子显微镜对复合材料的力学性能及断面的微观形貌进行了测试和表征。结果表明:碳纤维在HA/PMMA复合材料中分布均匀,有效提高了复合材料的力学性能;碳纤维含量为4%时,复合材料的拉伸强度、弯曲强度、压缩强度和弹性模量等均达到最大值;复合材料的断裂伸长率随碳纤维含量的增加而减小;当碳纤维含量一定时,随其长度的增加,复合材料的拉伸强度、弯曲强度和弹性模量均增加,但断裂伸长率降低。     

Interfacial Mechanical Characterization of Nicalon SiC Fiber/Alumina-Based Composites

Interfacial mechanical properties of both Nicalon SiC/aluminum borate and Nicalon SiC/aluminum phosphate with various fiber coatings and heat treatments were evaluated using a commercially-available indenter to induce fiber sliding during load cycling experiments. Varying degrees of sliding due to different coating materials were found. The interfacial characteristics including the shear, the residual axial fiber, and debond stresses were estimated by matching the experimental stress-displacement curves with curves predicted from an existing model. The elastic modulus and hardness of the interphase/interface in ceramic matrix composites were also evaluated. These results provided important insights into the ultimate mechanical performance of fiber-reinforced ceramic-matrix composites.     

Interfacial Mechanical Characterization of Nicalon SiC Fiber/Alumina-Based Composites

Interfacial mechanical properties of both Nicalon SiC/aluminum borate and Nicalon SiC/aluminum phosphate with various fiber coatings and heat treatments were evaluated using a commercially-available indenter to induce fiber sliding during load cycling experiments. Varying degrees of sliding due to different coating materials were found. The interfacial characteristics including the shear, the residual axial fiber, and debond stresses were estimated by matching the experimental stress-displacement curves with curves predicted from an existing model. The elastic modulus and hardness of the interphase/interface in ceramic matrix composites were also evaluated. These results provided important insights into the ultimate mechanical performance of fiber-reinforced ceramic-matrix composites.     

Preparation and properties of carbon fiber/ hydroxyapatite‐poly(methyl methacrylate) biocomposites

An in situ polymerization with a later solution co‐mixing approach was used in the preparation of polymethyl methacrylate (PMMA) matrix composites using hydroxyapatite (HA) nanoparticles and short carbon fibers(C_(f)) as reinforcing materials. The microstructures and fracture surface morphologies of the prepared C_(f)/HA‐PMMA composite were characterized using XRD, FTIR, SEM, EDS, and FESEM analyses. The mechanical properties of the composites were tested by a universal testing machine. Results show that the surface of nitric acid‐oxidized carbon fibers and lecithin‐treated HA contain new functional groups. Uniform dispersion of short fibers and HA nanoparticles in PMMA matrix is successfully achieved and the mechanical properties of the composites are obviously improved. The flexural strength, flexural modulus, and Young's modulus of the composites reach the maximum value 128.12 MPa, 1.150 GPa, and 4.572 GPa when carbon fiber and HA mass fraction arrive to 4% and 8%, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Interpenetrating polymer networks of polyurethane and furfuryl alcohol,IIa. Processability and properties of pultruded fiber-reinforced composites

A feasibility study of pultrusion of fiber-reinforced polyurethane/furfuryl alcohol (PU/FA) interpenetrating polymer/network IPN composites has been made. From the viscosity study, it was found that the pot life of the PU/FA IPN prepolymers increased with PU content and showed high reactivity at elevated temperature. It was confirmed from the morphological study that the wetting of fibers by the PU/FA IPN resins was improved with PU content. The appearance of the tensile failure surfaces of the pultruded glass fiber-reinforced PU/FA IPN composites showed “hackle patterns” for PU contents below 15 phr. The mechanical property study shows that the tensile strength of pultruded PU/FA IPN composites is the highest when the PU content is 5 phr. However, the flexural strength, flexural modulus and HDT decreased with PU content. The mechanical properties of various fiber-reinforced (glass, carbon, and Kevlar 49 aramid fiber) pultruded PU/FA IPN composites increased with fiber volume content.     

Microstructure and elastic properties of individual components of C/C composites

Carbon fiber reinforced carbon matrix (C/C) composites are often used for structural and frictional applications at a wide range of temperatures due to their excellent mechanical and thermal properties. Tailoring of mechanical properties through optimization of microstructure is critical for achieving maximum composite performance. This article addresses the evolution of the fiber and matrix microstructure and related nano-mechanical properties in two different C/C composites after being subjected to heat treatment at temperatures between 1800 and 2400 °C. Microstructure and corresponding nano-mechanical properties of C/C composites were studied using Polarized Light Microscopy (PLM), High-Resolution Transmission Electron Microscopy (HRTEM) and nanoindentation techniques. Increased heat treatment temperature (HTT) led to formation of a better-organized microstructure of fiber and matrix and also to formation of thermal cracks. The elastic modulus of rough laminar CVI pyrocarbon decreased from 18 to 12 GPa with increased HTT. In contrast, the isotropic CVI pyrocarbon and charred resin matrix displayed only a slight change of elastic modulus. The elastic modulus of PAN fiber increased from 18 to 34 GPa, indicating the development of a better-organized microstructure in the fiber-axial direction.     

Effect of prolonged water absorption on mechanical properties in cellulose fiber reinforced vinyl‐ester composites

With the increasing of worldwide societal awareness about environmental impact, sustainability, and renewable energy sources, the polymer natural fiber composites recently have attracted the attention of researchers due to the fact that they are recyclable and biodegradable. This study conducted a new infiltration method that involved very thin sheets of recycled cellulose fibers (RCF) being fully soaked in vinyl‐ester resin for the development of natural fiber reinforced polymer composites. The effect of prolonged water absorption on the mechanical behavior of cellulose fiber (0–50 wt%) reinforced vinyl‐ester composites was investigated. The elastic modulus of these composites was measured and the data were validated with various mathematical models. The modeling results revealed that the experimental data matched the prediction data obtained by the Cox–Krenchel model. Prolonged exposure of these composites to water absorption caused a reduction in elastic modulus, strength, and toughness. POLYM. ENG. SCI., 55:2685–2697, 2015. © 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     

Polyphenylene sulphide/carbon fiber composites: study on their thermal,mechanical and microscopic properties

The present study investigates the thermal, mechanical and microscopic properties of polyphenylene sulphide/carbon fiber (PPS/CF) composites by incremental number of fiber layers. The composites were prepared by hand lay-up technique followed by compression molding. A superior matrix-reinforcement adhesion was attained without the use of coupling agent and mechanical stability of the composites improved with increasing fiber layers. Transverse rupture strength and bending modulus were improved by 59.84 and 125.21 %, respectively, without loss in toughness. Impact strength and hardness values were enhanced while storage modulus, loss modulus and damping factor were dropped by increases in fiber layers. Thermogravimetric analysis (TGA) indicated a gradual rise in thermal stability (16.84 %) of the composite as compared to pure matrix. Surface morphology and crack propagation were studied by optical microscopy. It was found that crack was propagated in a linear plane by applying load. In addition, scanning electron microscopy (SEM) illustrated steady alignment of fibers and uniform distribution of the matrix around reinforcement. Based on the obtained results, fiber layers showed great potential for enhancement of thermal and mechanical properties of the composites.     

Effect of silicon carbide on the mechanical and thermal properties of ethylene propylene diene monomer-based carbon fiber composite material for heat shield application

In this article, the preparation of silicon carbide (SiC), carbon fiber (CF), and ethylene–propylene–diene monomer composite with different parts per hundred of SiC (phr) ratio (CF/SiC; 10/0, 0/10, 10/10, 10/15, 10/20) and its effect on mechanical and thermal properties have been studied. After the incorporation of SiC up to 20 phr with a stable CF (10 phr), composites demonstrated higher tensile properties up to 12.09 MPa, elongation at break (725%), modulus (3.5 MPa), and hardness (79 Shore-A) at composition (CF10SiC20 phr). Furthermore, the density of the composites has been achieved to a maximum value of 1.081 g/cm³ at composition (CF10SiC20 phr). The synthesized composite's functional group has been analyzed using Fourier-transform infrared spectroscopy. The thermal stability of the composites increased with the inclusion of SiC up to 20 wt% while achieving the 520°C described by thermogravimetric analysis. After gamma irradiation analysis, the mechanical properties of the composites were slightly enhanced. Thermal conductivity of the composites has been maintained up to 0.21 W/mK at CF10SiC20 phr of the composites. The morphology of silicon carbide and carbon fiber was examined using scanning electron microscopy.     

The effect of atmospheric plasma treatment of recycled carbon fiber at different plasma powers on recycled carbon fiber and its polypropylene composites

To increase the mechanical properties of recycled carbon fiber-reinforced polypropylene (PP) composites, recycled carbon fibers (RCF) were subjected to atmospheric plasma treatment at different plasma powers (100, 200, and 300 W). The changes on surface topography and roughness of RCF were examined by atomic force microscopy. Plasma treatment of RCF increased the roughness value of RCF. The variation of surface elemental compositions and tensile strength of RCF were determined by using X-ray photoelectron spectroscopy and tensile test, respectively. Plasma-treated RCF-reinforced PP composites were fabricated using high speed thermo-kinetic mixer. Plasma treatment of RCF at 100 W increased the tensile and flexural strength values of RCF-reinforced PP composites considerably by 17 and 11%, respectively. However, plasma treatment of RCF at higher plasma powers (200 W and 300 W) decreased tensile and flexural strength values of composites because of the etching of RCF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47131.     

A comparison between random model and periodic model for fiber‐reinforced composites based on a new method for generating fiber distributions

This article presents a new method to generate the random fiber distribution in transverse cross‐section of fiber reinforced composites with a desired high fiber volume fraction. The method, combined with random disturbance algorithm and perfect elastic collision algorithm, generates the Representative Volume Element (RVE) models through shifting fibers and avoiding fibers overlapped. The advantage of this algorithm is that it can study the continuous changing trends of both statistical characterizations and mechanical properties of the RVE models from periodic distribution to random distribution. Through analysis with compare, the generated distribution models present a convergence state after a designated disturbance time whether the initial periodic distribution is rectangular or hexagonal. We find that the transverse tensile moduli of rectangular model are higher than the random model while the hexagonal model is on the contrary. The transverse shear modulus of random model is higher than rectangular model and close to hexagonal model. POLYM. COMPOS., 38:77–86, 2017. © 2015 Society of Plastics Engineers     

Morphological and nanomechanical characterization of anisotropic interfacial characteristic regions in CF/PA6 composites at different cooling rates

Macroscopic tensile tests on neat PA6 and CF/PA6 prepregs showed that the cooling rate significantly affects the mechanical properties of CF/PA6 composites because of their different crystallization behaviors both at the fiber surface and in the matrix. Polarizing optical microscopy, static nanoindentation (SNI), and dynamic mechanical imaging (DMI) tests were used to characterize the anisotropic morphologies and nanomechanical performances of the interfacial characteristic regions in CF/PA6 composites at five different cooling rates. As a result, the seven interfacial characteristic regions inside the CF/PA6 composites were clearly distinguished. The interphase thickness of the CF/PA6 composites decreased with a decrease in the cooling rate. On the contrary, the interphase modulus and transcrystallinity thickness and modulus showed significant increases with a decrease in the cooling rate. The DMI and SNI test results were in agreement with each other and with the macromechanical test results. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44106.     

Low-temperature fast curable behavior and properties of bio-based carbon fiber composites based on resveratrol

Environmentally friendly materials are an integral part of sustainable chemistry, and bio-based polymer composites are an important class of materials. The manufacture of composites is expected to reduce or even eliminate the use of adjuvants, considering the importance of reducing energy consumption and avoiding health and environmental risks. In this study, a phenyl-containing, polyfunctional, bio-based epoxy resin (TGER) was synthesized, and carbon fiber-reinforced, bio-based epoxy resin composites were fabricated by vacuum-assisted resin infusion using two aromatic amine curing agents, 4,4′-diaminodiphenylmethane (DDM) and 3,3′-diethyl-4,4′-diaminodiphenylmethane (DEDDM). Curing reactions and rheological behavior studies showed that TGER had higher curing reactivity toward DDM and DEDDM than to diglycidyl ether of bisphenol A (DGEBA) and possessed good processability. The results indicated that the resveratrol-based epoxy resin displayed low-temperature fast curing properties. The evaluation of the mechanical properties of the carbon fiber composites showed that the flexural strengths of CF/TGER/DDM and CF/TGER/DEDDM were 520 and 628 MPa, respectively. The initial decomposition temperature of CF/TGER composites is above 200°C. Furthermore, the carbon fiber–reinforced biopolymers possess excellent heat resistance. Therefore, carbon fiber-reinforced, resveratrol-based epoxy resin composites are promising candidates as alternatives to petroleum-based high-performance carbon fiber composites.