Carbon Fiber Reinforced Polyphenylene Sulfide Research Articles

Effect of aminated polyphenylene sulfide on the mechanical properties of short carbon fiber reinforced polyphenylene sulfide composites

Abstract The aim of this study was to investigate the effect of the aminated polyphenylene sulfide (PPS-NH 2 ) used as compatibilizer on the mechanical properties of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) composites. The compatibilizers PPS-NH 2 which were synthesized by the condensation polymerization of sodium sulfide (Na 2 S), p-dichlorobenzene (DCB), and the third active monomer 2,5-dichloroaniline (DCA). Composites with 20 wt% CF, 75 wt% PPS and 5 wt% PPS-NH 2 which were synthesized by different mole ratios of Na 2 S/DCB/DCA were prepared by melt blending and injection molding. According to the results of mechanical properties tests, dynamic mechanical analysis (DMA), microbond test (apparent interfacial shear strength, τ app ) and scanning electron microscopy (SEM), the compatibilizers PPS-NH 2 could improve the macro-mechanical properties and interfacial bonding between CF and PPS matrix.

Fibre–matrix interfaces in carbon fibre reinforced PPS composites: damage initiation and propagation in tensile tests

This paper investigates the effect of fibre-matrix adhesion on the local strain development, as measured by the Digital Image Correlation technique, and on damage initiation and propagation in ±45° and 0° tensile tests of 5HS carbon fibre reinforced Polyphenylene sulphide. The sides of both ±45° and 0° samples have been monitored by a high-speed camera during testing. Scanning electron microscopy (SEM) analysis of cross-sections of samples tested up to different strain levels has been performed to help the identification of the main failure mechanisms. In the case of 0° tensile tests, the fractured samples’ sides have been also observed by optical microscopy and the fracture areas have been analysed by SEM. In the ±45° tensile tests, strain concentration is observed in the middle of the samples with low fibre-matrix adhesion, where the interface is not able to transfer the load to the fibres in the outer part of the sample, contrary to what happens in samples with good bonding. A fragile failure is observed in samples with good interfacial bonding, whereas a very extensive delamination failure is obtained in samples with poor interface. In the 0° tensile tests, local strain concentrations develop at each weave cross-over points in composites with poor fibre-matrix adhesion. This leads to weft fibre bundle debonding from the resin and eventually to extensive delamination. A more uniform strain field is observed in samples with good fibre-matrix adhesion, where a fragile type of failure is obtained.

Compression After Impact and Fatigue of Reconsolidated Fiber-reinforced Thermoplastic Matrix Solid Composite Laminate

Carbon fiber-reinforced poly-phenylene sulfide laminate coupons were impacted at low-energy in a drop-tower machine and subsequently fatigued in a four-point bending fixture. The doubly damaged test pieces were then hot-press reconsolidated and inspected nondestructively by vibrothermography to check their structural integrity. The residual mechanical properties of the laminate in both the as-damaged and as-repaired conditions were determined by compression loading with the in-plane strain fields determined via a digital image correlation system. Cross-section views of damaged and repaired samples were analyzed by light optical microscopy and correlated to residual mechanical properties, as were the digital image correlation and nondestructive test results. Based on the values of stiffness and ultimate strength of the repaired laminates, 10J was inferred as the maximum impact energy at which it is worthwhile performing hot-press reconsolidation, in view of the applied fatigue history following impact.

The prediction of process-induced deformation in a thermoplastic composite in support of manufacturing simulation

Digital manufacturing techniques can simulate complex assembly sequences using computer-aided design–based, ‘as-designed’ part forms, and their utility has been proven across several manufacturing sectors including the ship building, automotive and aerospace industries. However, the reality of working with actual parts and composite components, in particular, is that geometric variability arising from part forming or processing conditions can cause problems during assembly as the ‘as-manufactured’ form differs from the geometry used for any simulated build validation. In this work, a simulation strategy is presented for the study of the process-induced deformation behaviour of a 90°, V-shaped angle. Test samples were thermoformed using pre-consolidated carbon fibre–reinforced polyphenylene sulphide, and the processing conditions were re-created in a virtual environment using the finite element method to determine finished component angles. A procedure was then developed for transferring predicted part forms from the finite element outputs to a digital manufacturing platform for the purpose of virtual assembly validation using more realistic part geometry. Ultimately, the outcomes from this work can be used to inform process condition choices, material configuration and tool design, so that the dimensional gap between ‘as-designed’ and ‘as-manufactured’ part forms can be reduced in the virtual environment.

Experimental investigation of thermoforming carbon fibre-reinforced polyphenylene sulphide composites

Pre-consolidated carbon fibre-reinforced polyphenylene sulphide (CF/PPS) laminates were thermoformed into V-shaped parts via designed out of autoclave thermoforming experiments. The different processing conditions tested in the experiment have resulted in final part angles whose differences ranged from 2.087 to 3.431° from the original mould angle. The test results show that processing conditions influenced finished part dimensions as the final sample angles were found to decrease relative to the tooling dimensions, as mould temperature increases. Higher mould temperature conditions produce thinner parts due to the thermal expansion of mould tools. The mould temperature of 170°C, which can produce parts with high degree of crystallinity as well as small size of crystal, has been established as the optimal thermoforming condition for CF/PPS composites.

Interfacial shear strength of carbon fiber reinforced polyphenylene sulfide measured by the microbond test

Interfacial micromechanical performance of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) composite was studied by the microbond test. A novel homemade apparatus which is operated simply was employed and a different microsample preparation method was introduced. Comparative tests at various loading speeds were made to investigate the influence of testing rate on the interfacial shear strength of CF/PPS micro-composite. It was found that the interfacial shear strength increased with increasing fiber embedded length at speeds below 0.02 mm/s and above 0.04 mm/s, but it was constant between 0.02 and 0.04 mm/s. It is recommended to perform the microbond test in the test rate range of 0.02–0.04 mm/s, where the interfacial shear strength does not change with the embedded length and no significant deviations are observed, thus could better reflect the true interface strength of the composite.

Process and performance evaluation of ultrasonic, induction and resistance welding of advanced thermoplastic composites

The possibility of assembling through welding is one of the major features of thermoplastic composites and it positively contributes to their cost-effectiveness in manufacturing. This article presents a comparative evaluation of ultrasonic, induction and resistance welding of individual carbon fibre-reinforced polyphenylene sulphide (PPS) thermoplastic composite samples that comprises an analysis of the static and dynamic mechanical behaviour of the joints as well as of the main process variables. The induction welding process as used in this research benefitted from the conductive nature of the reinforcing fibres. Hence, no susceptor was placed at the welding interface. Resistance welding used a fine-woven stainless-steel mesh as the heating element and low welding pressures and times were applied to prevent current leakage. Triangular energy directors moulded on a separate tape of PPS resin were used to concentrate ultrasonic heat at the welding interface. The static single-lap shear strength of the joints was found similar for induction and ultrasonic welding. A 15% drop in the static mechanical properties of the resistance welded joints was attributed to incomplete welded overlaps following current leakage prevention. However, the fatigue performance relative to the static one was similar for the three sorts of joints. A comparative analysis of process variables such as welding time, required power and energy was also carried out.

Laser processing of continuous carbon fibre reinforced polyphenylene sulphide organic sheets—Correlation of process parameters and reduction in static tensile strength properties

In this article, the impact of laser-induced thermal damage on the static strength properties of consolidated continuous carbon fibre reinforced thermoplastics induced by high-power laser cutting is presented. Organic sheets based on a polyphenylene sulphide matrix are machined using a fibre laser providing a maximum output power of 6000 W. In this context, the influence of the applied laser power and the feed rate on the cut quality as well as the resulting tensile strength is discussed. In order to analyse the laser cutting edge through a quantitative evaluation of the damaged areas due to laser impact, optical micrographs are prepared. The results of tensile strength tests are compared with those measured from the specimens that were generated by a conventional processing technique (milling). A linear dependency between a specific part of the heat-influenced zone and the corresponding maximum tensile load is found. A reduced load bearing area, as a consequence of a modified fibre–matrix-structure due to laser impact, is identified as the responsible factor for reduced tensile strengths, especially for low feed rates.

Avaliação dos comportamentos mecânico e térmico de laminados de PPS/fibra de carbono processados em autoclave sob diferentes ciclos de consolidação

Usualmente, um dos processos mais utilizados para fabricação de componentes em termoplásticos estruturais é a moldagem por compressão a quente, porém restringindo-se na obtenção de peças de pequeno e médio porte. Tal restrição deve-se à limitação do tamanho das prensas utilizadas, principalmente pelo custo envolvido. Procurando ampliar a aplicação de compósitos termoplásticos, possibilitando a fabricação de peças maiores e com maior potencial de integração, pelo uso de infra-estrutura já disponível em processadores de compósitos, este trabalho aborda o processamento de laminados de poli(sulfeto de fenileno) (PPS) reforçado com fibra de carbono em autoclave, pelo uso de quatro diferentes ciclos de consolidação. Os laminados obtidos foram caracterizados por inspeção por ultrassom, análises de DSC para a determinação da cristalinidade e avaliação das propriedades mecânicas em flexão, compressão e cisalhamento interlaminar. Os resultados mostram que laminados obtidos com taxas de resfriamento mais lentas apresentam menor resistência e módulo em compressão, uma vez que o maior grau de cristalinidade (~30%) promove maior fragilização da matriz polimérica.

Processing and Nonisothermal Crystallization Kinetics of Carbon/PPS in Single Diaphragm Forming

Single diaphragm forming (SDF) has been used in manufacturing high-quality thermoplastic composite sheet parts with complex geometries. However, temperature gradients through the thickness may exist in the composites, especially for thick, high temperature, semicrystalline composites. The thermal gradient may introduce residual stresses, which may degrade the mechanical properties or warp the part. Therefore, investigating temperature profile through the thickness during processing can improve the quality of SDF composite parts. A laboratory scale SDF with a cooling system was built for the temperature study through the thickness. Carbon fiber reinforced polyphenylene sulphide (carbon/PPS) was used for the temperature study, and the effect of cooling rate on the nonisothermal crystallization of the carbon/PPS was also investigated using differential scanning calorimeter. The start crystallization temperature and the peak crystallization temperature decrease with increasing cooling rates. A combination of Avrami and Ozawa theory was successfully used in the work for describing the crystallization kinetics, and the crystallization activation energy was determined for the carbon fiber reinforced PPS.

On the feasibility of optical fibre sensors for strain monitoring in thermoplastic composites under fatigue loading conditions

This study investigates the possibility of using optical fibres with Bragg gratings for measurements in thermoplastic composites under fatigue loading conditions. Two setups are considered: (i) the fibre is embedded in the composite and (ii) the grating is bonded externally. Detailed information is given on the principle of optical fibre measurements and the data acquisition for both setups. To verify the strain derived from the optical fibre, the strain is compared with extensometer measurements. A special design of the blades of the extensometer is presented, since the standard blades suffer from a loss of grip on the surface of the specimen. The material used for this study was a carbon fibre-reinforced polyphenylene sulphide. It can be concluded for both setups that the optical fibre survives over half a million loading cycles, without de-bonding of the fibre. The advantage of the external fibre over the embedded one is that it can be mounted after manufacturing of the plate, but it has a higher risk of being damaged during working conditions of the component.

The use of rivets for electrical resistance measurement on carbon fibre-reinforcedthermoplastics

The use of fibre-reinforced thermoplastics, for example in the aeronautical industry, isincreasing rapidly. Therefore, there is an increasing need for in situ monitoring tools, whichpreferably have limited influence on the behaviour of the material and which are easy touse. Furthermore, in the aeronautical industry composites are very often attached withrivets.In this study, the possibility of the use of rivets as contact electrodes for electricalresistance measurement is explored. The material used is a carbon fibre-reinforcedpolyphenylene sulphide. First, the set-up used is discussed. Then, static tensile tests on thelaminate are performed. The possible influence of an extensometer on the measurements isexamined. Furthermore, failure predictability is assessed. It may be concluded that theproposed set-up with the rivets can be used for electrical resistance measurement, with theability to predict failure, and that the extensometer has a negative influence on theresistance measurement.

UK charity picked for energy-saving trials

Long fiber thermoplastic composite (LFT) is one type of thermoplastic polymer matrix composites reinforced with discontinuous fibers above critical fiber length. It has been increasingly used in various applications due to its excellent specific strength and specific modulus in addition to its infinite shelf life, intrinsic recyclability, and high-volume processability even for complex geometries. In this work, long carbon fiber reinforced polyphenylene sulphide (LFT C/PPS) is used to prototype a helmet insert with high rigidity for stiffening a relatively soft ballistic shell. The helmet insert is designed to have a rim along its periphery in order to offer extra rigidity and facilitate a readily clip-on with the ballistic shell. Static structural analysis is carried out for evaluating the performance of the insert. Comparison was made among different patterns of the helmet insert in their rigidity. A compression molding tool is designed and machined and the helmet insert is prototyped using LFT C/PPS. A compression test is conducted for the ballistic shell integrated with the helmet insert to validate the stiffening capability of the LFT C/PPS helmet insert.

Strain Monitoring in Thermoplastic Composites with Optical Fiber Sensors: Embedding Process, Visualization with Micro-tomography, and Fatigue Results

This study investigates the possibility of using optical fibers with Bragg gratings for measurements under fatigue loading conditions. Detailed information is given on the principle of optical fiber measurements, the embedding process, and the fatigue tests. To verify the strain derived from the optical fiber, the strain is compared with extensometer measurements. A special design of the blades of the extensometer is presented, since the standard blades suffer from a loss of grip on the surface of the specimen. Furthermore, X-ray micro-tomography is discussed and used for the visualization of the optical fibers and damage in the composite material. The material used for this study is a carbon fiber-reinforced polyphenylene sulfide. It can be concluded that the optical fiber survives over half a million loading cycles, without de-bonding of the fiber. Furthermore, the resolution of the microtomography is high enough to visualize not only the optical fiber, but also damage in the material.

Tribological behavior of the carbon fiber reinforced polyphenylene sulfide (PPS) composite coating under dry sliding and water lubrication

Carbon fiber reinforced polyphenylene sulphide (PPS) composite coatings (the mass fraction of the carbon fiber varied from 1 to 5 wt%) were prepared by flame spraying. The microstructure and physical properties of the composite coating were studied. The friction and wear characteristics of the PPS coating and carbon fiber reinforced PPS composite coating under dry- and water-lubricated sliding against stainless steel were comparatively investigated using a block-ring tester. The composite coatings showed lower friction coefficient and higher wear rate than pure PPS coatings under dry sliding. Under water-lubricated condition, the composite coatings showed better wear resistance than under dry. Under water-lubricated condition the tribological behaviors of the 3 wt% carbon fiber reinforced composite coating also were investigated under different sliding speed and load. The result showed that the sliding speed had little effect on the tribological properties, but the load affected greatly on that of the composite coatings. The morphologies of the worn surfaces of the composite coatings and the counterpart steel were analyzed by means of scanning electron microscopy (SEM), coupled with an energy-dispersive X-ray spectrometer (EDS) for compositional analysis.

Investigation of load bearing performances of pin connected carbon/polyphenylene sulphide composites under static loading conditions

The bearing strength of pin connections highly depends on joint and material parameters such as connection geometry, fibre orientation, layer orientation, pressure distribution along the plate thickness, etc. In order to investigate the bearing performance of the pin-loaded unidirectional carbon fiber reinforced polyphenylene sulphide (PPS) matrix composites, experiments have been carried out according to the ASTM D953 standards using Instron 4411. It is observed that pin loading performance has close relationship with fibre orientation of laminates and their deformation characteristics. Also the geometric parameters of end distance from the hole centre ( E) and width of the plate ( W) and pin diameter ( D) remarkably affect the load bearing performance of the materials. Joint failure with the net tension and shear-out modes is catastrophic and immediate. But bearing failure is progressive. Also fractoraphic investigations were performed to understand the deformations of the material with respect to the fiber orientations.

Residual strain development in an AS4/PPS thermoplastic composite measured using fibre Bragg grating sensors

Abstract This paper demonstrates the use of fibre Bragg grating (FBG) sensors for the measurement of residual strain development during the consolidation of a thermoplastic composite. During the processing of the carbon fibre-reinforced polyphenylene sulphide (AS4/PPS) laminate, FBG sensors respond to changes in material state, for example the glass-rubber transition and solid–liquid transition. The sensors also permit the observation of wavelength shifts and spectral form changes induced by the contraction of the composite during cooling. The experimental data are compared to a generalized plane strain, thermoelastic numerical model with temperature dependent matrix dominated properties. The model provides solutions for two limiting cases: one where the specimen contracts freely, and one where the specimen is restricted by perfect contact with the mould. Strain values calculated in each case are inserted into optomechanical equations, which convert the strain state in the FBG to a corresponding change in wavelength. In this way, the modelled cases are compared to FBG wavelength shifts during consolidation.

An Investigation of the Dynamic Response of Continuous Fibre Reinforced Composite Laminates - Failure Morphology

By using the split Hopkinson pressure bar technique, impact tests were carried out on fully clamped three-point bending, laminated beam specimens made from continuous glass fibre and carbon fibre reinforced polyphenylene sulphide of three different lay-up sequences. This paper focuses on scanning electron microscope investigations of the impact failure morphology, with the aim of providing a phenomenological background for a new model which can describe the dynamic response behaviour during transverse impact, as well as understanding comprehensively the dominant failure patterns at high strain rate. The results show that the fracture morphology possesses distinct features for each type of laminate, and is a function of both the material characteristics and lay-up sequence. Fibre to matrix adhesion exerts a strong influence on the microcracking mechanism.

An Investigation of the Dynamic Response of Continuous Fibre Reinforced Composite Laminates - Failure Morphology

By using the split Hopkinson pressure bar technique, impact tests were carried out on fully clamped three-point bending, laminated beam specimens made from continuous glass fibre and carbon fibre reinforced polyphenylene sulphide of three different lay-up sequences. This paper focuses on scanning electron microscope investigations of the impact failure morphology, with the aim of providing a phenomenological background for a new model which can describe the dynamic response behaviour during transverse impact, as well as understanding comprehensively the dominant failure patterns at high strain rate. The results show that the fracture morphology possesses distinct features for each type of laminate, and is a function of both the material characteristics and lay-up sequence. Fibre to matrix adhesion exerts a strong influence on the microcracking mechanism.