Structural Design Strategies of Polymer Matrix Composites for Electromagnetic Interference Shielding:A Review

With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.

A comprehensive review on material selection for polymer matrix composites subjected to impact load

Polymer matrix composites(PMC)are extensively been used in many engineering applications.Various natural fibers have emerged as potential replacements to synthetic fibers as reinforcing materials composites owing to their fairly better mechanical properties,low cost,environment friendliness and biodegradability.Selection of appropriate constituents of composites for a particular application is a tedious task for a designer/engineer.Impact loading has emerged as the serious threat for the composites used in structural or secondary structural application and demands the usage of appropriate fiber and matrix combination to enhance the energy absorption and mitigate the failure.The objective of the present review is to explore the composite with various fiber and matrix combination used for impact applications,identify the gap in the literature and suggest the potential naturally available fiber and matrix combination of composites for future work in the field of impact loading.The novelty of the present study lies in exploring the combination of naturally available fiber and matrix combination which can help in better energy absorption and mitigate the failure when subjected to impact loading.In addition,the application of multi attributes decision making(MADM)tools is demonstrated for selection of fiber and matrix materials which can serve as a benchmark study for the researchers in future.

Prediction of Viscoelastic Behavior of Unidirectional Polymer Matrix Composites

To develop a novel method predicting the viscoelastic behavior of polymer matrix composites according to the viscoelasticity of the matrix, we used the viscoelastic model of the matrix to build new models for unidirectional composites in both 0° and 90° directions. Viscoelastic parameters for both new models were derived, and the obtained equations shared the same form as the viscoelastic constitutive equation of matrix material. The viscoelastic behaviors of matrix material and unidirectional composites were also tested. Results showed that fitting parameters of creep compliance equation were close to the theoretical values of viscoelastic constitutive parameters of the unidirectional composites, proving the validity of the models. A new method was obtained to predict the viscoelastic property of the unidirectional composites based on the viscoelastic property of composite matrix and elastic property of the unidirectional composites. This method provides a theoretical basis for future studies on the viscoelasticity of composite laminates.

Thermal conductivity model of filled polymer composites

Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was discussed.Silica with high thermal conductivity was chosen to mix with polyvinyl-acetate （EVA） copolymer to prepare SiO2/EVA co-films.Experimental data of the co-films＇ thermal conductivity were compared with some classical theoretical and empirical models.The results show that Agari＇s model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.

Inherent relationship between process parameters,crystallization and mechanical properties of continuous carbon fiber reinforced PEEK composites

High-performance thermoplastic composites have been developed as significant structural materials for cutting-edge equipment in the aerospace and defence fields.However,the internal mechanism of processing parameters on mechanical properties in the manufacturing process of thermoplastic composite structures is still a serious challenge.The purpose of this study is to investigate the process/crystallization/property relationships for continuous carbon fiber(CF)reinforced polyether-ether-ketone(PEEK)composites.The composite laminates are fabricated according to orthogonal experiments via the thermoforming method.The mechanical performance is investigated in terms of crystallization properties and fracture morphology characterizations.Experimental results show that the mechanical performance and crystallization properties of thermoplastic composites are significantly affected by the coupling of processing parameters.The increased molding temperature,pressure,and holding time improve the degree of fiber/matrix infiltration and affect the crystallinity and crystalline morphology of the matrix,which further influences the mechanical properties of the composites.This is reflected in the test results that crystallinity has an approximately linear effect on mode-I interlaminar fracture toughness and transverse flexural modulus.As well as the higher molding temperature can destroy the pre-existent crystals to improve the toughness of the matrix,and the well-defined crystalline structures can be observed when fabricated at higher temperatures and longer periods of holding time.

Nonlinear Micromechanical Modelling of Transverse Tensile Damage Behavior in Fiber-Reinforced Polymer Composites

The investigation focusing on the mechanical behaviors at the microstructural level in composite materials can provide valuable insight into the failure mechanisms at larger scales.A micromechanics damage model which comprises the coupling of the matrix constitutive model and the cohesive zone(CZM)model at fiber-matrix interfaces is presented to evaluate the transverse tensile damage behaviors of unidirectional(UD)fiber-reinforced polymer(FRP)composites.For the polymeric matrix that exhibits highly non-linear mechanical responses,special focus is paid on the formulation of the constitutive model,which characterizes a mixture of elasticity,plasticity as well as damage.The proposed constitutive model includes the numerical implementation of a fracture plane based ellipse-parabola criterion that is an extension of the classic Mohr-Coulomb criterion,corresponding post-yield flow rule and post-failure degradation rule in the fully implicit integration scheme.The numerical results are in good agreement with experimental measurements.It is found that directly using the matrix properties measured at the ply level to characterize the mechanical responses at the constituent level may bring large discrepancies in homogenized stress-strain responses and dominant failure mechanisms.The distribution of fracture plane angles in matrix is predicted,where it is shown to provide novel insight into the microscopic damage initiation and accumulation under transverse tension.

Fabrication and Characterization of Glass Fiber with SiC Reinforced Polymer Composites

Glass Fiber Reinforced Polymeric (GFRP) Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, the tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechanical properties like yield strength, yield strain, Young’s modulus, flexural modulus, and impact energy were investigated. The mechanical properties of the GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites were modelled and compared with measured values. The results show that composites with epoxy resin demonstrate higher strength and modulus compared to composites with polyester resin.

Production and characterisation of new bioresorbable radiopaque Mg–Zn–Y alloy to improve X-ray visibility of polymeric scaffolds

For the medical diagnosis,radiopaque materials(RM)made from high specific gravity elements like Pt,Au,Ta,Iodine,Bromine are either attached or blended or coated on an implant to makes it detectable under X-ray/Fluoroscopy/CT-Scan.RM facilitate the surgeon in an operation theatre to position an implant during the surgery.Mainly,RM are non-degradable,thus in case of biodegradable implants,it may detach from the body and accumulate in vital organ cause serious health issue.Therefore,a new bioresorbable radiopaque material(BRM)was produced by alloying the high specific gravity elements Zn(35%w/w)and Y(4%w/w)with Mg metal.In this alloy,three main phases were identified,alpha Mg,Mg_(7)Zn_(3)and icosahedral quasicrystalline I-phase Mg3Zn6Y,which reinforce the Mg matrix.Hereafter,BRM was powdered to a size of less than 25 microns and blended in different ratios with bioresorbable poly-L-lactic acid(PLLA)for fabricating PLLA/BRM bio-composite.BRM microparticles were uniformly distributed and interfacial bonded with the matrix.The X-ray was passed through bio-composite to captureμCT radiograph for evaluating linear attenuation co-efficient(μ)and optical density(OD).Thermal analysis reveals that BRM particles act as a nucleating site and enhance the crystallinity of the polymeric chain.During the In Vitro accelerated degradation study,the alkaline nature of BRM neutralise the acidity of PLLA and balance the pH of the body fluid to reduce the inflammatory reactions,but this compromises the stability of the polymer as it increases the decomposition rate.

Inter laminar shear strength behavior of acid,base and silane treated E-glass fibre epoxy resin composites on drilling process

In this present work siliconized e-glass fibre reinforced epoxy resin composite has been prepared and compared with acid and base treated e-glass fibre epoxy composites to know the significant advantage of silane treatment on fibre. The composites were fabricated by laying 20, 30 and 40vol% of e-glass fibre into epoxy resin matrix. The e-glass fibre woven mat was surface treated by an amine functional coupling agent 3-Aminopropyletrimethoxysilane(APTMS). The fibres were surface treated by aqueous solution method and thermo assisted to create silinol groups. Similarly for acid treatment H_2SO_4 and base treatment Na OH with 1N concentration was used for surface treating the fibres. Effectiveness of silane treatment on glass fibre was compared by inter laminar shear strength test according to ASTM D 2344.Drilling process with varying diameter drill bit and varying cutting speed was applied to check the composites for their delamination resistance while machining. Maximum improvement of 15%, 12.5% and9%(20, 30 and 40 vol %) on ILSS was achieved for siliconized e-glass fibre reinforced epoxy composites.The scanning electron microscopy images revealed that no fibre pull out was present on fractured surfaces of composites which contains siliconized e-glass fibre. Similarly better dimensional accuracy was achieved on drilling process for composites contains siliconized e-glass fibre.

Longitudinal Compressive Failure of Multiple-Fiber Model Composites for a Unidirectional Carbon Fiber Reinforced Plastic

The longitudinal compressive failure of a unidirectional carbon fiber reinforced plastic (CFRP) was studied using multiple-fiber model composites. Aligned carbon fibers were embedded in an epoxy matrix and put on a rectangular beam. A compression test of the model composite was performed by means of a four point bending test of the rectangular beam. The number of carbon fibers was changed from one to several thousands, by which the effect on compressive failure modes was investigated. A compressive failure of a single-fiber model composite was fiber crush. The fiber crush strain was much higher than the compressive failure strain of the unidirectional carbon fiber reinforced plastic. By contrast, a compressive failure of a multiple-fiber model composite was kink-band. The longitudinal compressive failure mechanism shifted from fiber crush to kink-band due to an increasing number of fibers. Kink-band parameters i.e. kink-band angle and kink-band width were dependent on the number of closely-aligned carbon fibers.

Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing

The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester （G/IPE）, carbon/isopolyester （C/IPE）, glass/vinylester （G/VE） and carbon/vinylester （CNE）, was investigated in this paper. Laminates 3 and 10 mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength （ILSS） degradations were studied. Moisture diffusion was observed to be anamolous to the Fick＇s law for both 3 and 10 mm thick samples in the later stage of diffusion. Moisture permeability of 10 mm thick samples was two to three order greater than that of 3 mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for CNE and 7% for GriPE. The residual flexural strength and ILSS were greater in case of 10 mm thick specimens after 200 days of exposure. SEM examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10 mm thick specimens.

INTERFACE REACTION BETWEEN γ-AMINOPROPYLTRIMETHOXYSILANE AND ULTRAVIOLET IRRADIATED POLYPROPYLENE

The interface reaction between ultraviolet irradiated polypropylene (UV-PP) and an amino silane coupling agent, γ-aminopropyltrimethoxysilane (γ-APS) adsorbed on glass fibers has been investigated by means of the combining use of solvent extraction and FTIR as well as XPS. First, polypropylene (PP) physisorbed on the glass fibers surface was removed by the solvent extraction in order to minimize the effect of the PP siginal in FTIR and XPS analyses. Second, the remaining glass fibers after solvent extraction were analyzed by FTIR and XPS. The results show that the absorption bands of PP still exist in the FTIR spectrum and two new bands of N1s at 399. 1eV and 401.6eV appear in the XPS spectrum for the composite with UV-PP and γ-APS treated glass fibers. Thus, the interface reaction between the UV-PP and γ-APS has been monitored directly. In addition, it may be concluded that OH and COOH groups of UV-PP form chemical bonds with NH2 group of γ-APS , respectively.

Electric memory effects in styrene-butadiene rubber, containing electric inclusions of highly aromatic oil

It was determined that samples of styrene-butadiene rubber(SBR),containing highly aromatic oil,exhibit memory effects giving rise to dynamic elastic modulus,damping and internal stresses degree which can be tailored depending on the applied electric field strength.The capability and stability of the interaction process between aligned neighbor dipoles for exhibiting a memory effect,once the aligning electric field was removed are studied.It is determined that depending on the spatial arrangement and the amount of electric charge of the dipoles,this interaction is able to promote a memory effect which keeps the alignment between them.This electrostatic interaction plays the role of a counteracting effect for keeping the alignment,which was called electroelasticity.The results from the developed model were applied successfully to SBR composite samples for explaining the memory effects recorded from dynamic mechanical analysis(DMA)measurements under electric field.In addition,the model of the electric inclusion based on the inclusion theory for continuous media,was applied to determine the degree of internal stresses in the dielectric composite material due to the external applied electric field.In addition,from the coupling between the model developed here and simple issues related to the mechanical properties of composite materials,a procedure for determining the maximum possible gap between the electric dipoles in composite dielectric materials is also shown.