Carbon Fiber Reinforced Epoxy Polymer Research Articles

Selective Cu electroplating enabled by surface patterning and enhanced conductivity of carbon fiber reinforced polymers upon air plasma etching

We demonstrate a sustainable post-processing of carbon fiber reinforced epoxy polymer (CFRP) composites by air plasma etching that permits regular electroconductive surface patterning through direct Cu galvanic metallization, in contrast to the untreated composite. Our study reveals a significant property dependence of the composite with respect to the position to the fiber/matrix composite surface and treatment. The enhancement in electrical conductivity was not compromised by the lower structural integrity of the composite, as the embedded carbon fibers remained unaffected by the air plasma etching process. The metallized Cu domains on the composite exhibit good hardness and excellent solderability potential. Thus, the electroconductive surface patterning of the composite, preceding galvanic metallization, facilitates the selective deposition of Cu layer domains. This step by step process, relying on the creation of selective electroconductive areas on the composite by plasma etching, enables galvanic metallization. Consequently, it enhances the potential for multifunctional composite applications. The feasibility of galvanic metallization brings new perspectives in selective metallization of composites by allowing the tailoring of the metal layer thickness, microstructure and selection of the metal.

Mechanical and electromagnetic response of carbon fiber reinforced epoxy polymer composites at different orientations

AbstractT‐300 6K carbon fabric fiber‐reinforced epoxy laminated composites are prepared by in‐situ and hot‐compression molding technique. The main emphasis of this study is to examine the impact of the structural deformations on fiber orientations of laminated composites during vibrational damping, stiffness, and electromagnetic interference (EMI) shielding properties. The damping properties of carbon fiber laminated composites are analyzed in terms of natural frequency and logarithmic decrement. The digital image correlation technique has been used to measure the mode shape behavior of carbon fiber reinforced polymer (CFRP) composites. The dynamic behavior of the CFRP laminated composites has significant effect on the fiber orientations in terms of storage, loss modulus, and damping ratio. The value of EMI shielding of CFRP laminated composites of T‐300 6K based CFRP polymer laminated composites has slight variations in the SET and their values are 107.17 (B‐45), 106.33 (B‐30), and 110.0 dB (B‐0). The vibrational and EMI shielding properties are showing a huge potential for these kinds of CFRP laminated composites in military and aircraft applications.Highlights CFRP laminated epoxy composites were fabricated by hand layup technique. The ply orientation of CFRP composites were affected the mechanical properties. DIC was used to determine the mode shapes of laminated composites. CFRP laminated composite exhibited excellent EMI properties.

Modelling damage evolution of carbon fiber-reinforced epoxy polymer composites in seawater sea sand concrete environment

The paper aims to study the damage mechanism and damage evolution of carbon fiber-reinforced epoxy polymer (CFRP) composites under seawater sea sand concrete (SWSSC) environment in coastal, marine and ocean engineering. CFRP composites were exposed into the simulated SWSSC solution to carry out the accelerated corrosion experiment at 25 °C, 40 °C and 55 °C, respectively. The degradation mechanism was revealed using scanning electrical microscope, X-ray microscope and Fourier transform infrared spectroscopy. The damage of CFRP composites is mainly induced by the hydrolysis of cured epoxy resin, and this process is accelerated in alkaline environment because the hydroxyl ions can react with the carboxylic acid resulting from hydrolyzation. Two approaches, chemical etching rate-based method and hydroxyl ions diffusion-based method, have been proposed. Their corresponding finite element models have been developed to predict the degradation of CFRP bars. The fidelity of the two approaches has been validated by comparing the predicted results with the test data.

Mechanical Performance of Bio-Based FRP-Confined Recycled Aggregate Concrete under Uniaxial Compression.

This research investigates the effectiveness of bio-sourced flax fiber-reinforced polymer in comparison with a traditional system based on carbon fiber-reinforced epoxy polymer in order to confine recycled aggregate concretes. The experimental investigation was conducted on two series of concrete including three mixtures with 30%, 50%, and 100% of recycled aggregates and a reference concrete made with natural aggregates. The concrete mixtures were intended for a frost environment where an air-entraining agent was added to the mixture of the second series to achieve 4% air content. The first part of the present work is experimental and aimed to characterize the compressive performance of confined materials. The results indicated that bio-sourced composites are efficient in strengthening recycled aggregates concrete, especially the air-entrained one. It was also found that the compressive strength and the strain enhancement obtained from FRP confinement are little affected by the replacement ratio. The second part was dedicated to the analytical modeling of mechanical properties and stress–strain curves under compression. With the most adequate ultimate strength and strain prediction relationships, the full behavior of FRP-confined concrete can be predicted using the model developed by Ghorbel et al. to account for the presence of recycled aggregates in concrete mixtures.

Assessment of moisture barrier, mechanical, and thermal property of base/nanophased carbon-epoxy composites in seawater

Polymeric composites absorb moisture by quick surface absorption followed by slow diffusion through the matrix in humid environment. Moisture absorption damages the matrix and interface of fiber reinforced polymer (FRP) composites and consequently, weakens their mechanical and thermal properties. Effects of seawater on mechanical and thermal behavior of base and nanophased carbon fiber reinforced epoxy polymer (CFRP) composites were investigated in this study. It was observed that moisture barrier property of carbon/epoxy composites can be improved by adding a small amount (1 to 3% by weight) of nanoclay as filler. Base and nanophased carbon/epoxy composite panels were fabricated by the vacuum assisted resin transfer molding (VARTM) process and samples were prepared from these panels for mechanical and thermal testing according to ASTM standards. Some of these samples were exposed to seawater for 180 days. Moisture intake by the samples was measured every 10 days for 90 days by which time samples reached a saturated state. Mechanical and thermal behavior of base and nanoclay-infused carbon/epoxy composites with exposure to seawater for 180 days were compared with those with no exposure to seawater for 180 days. Mechanical characterization was performed by compression test. Thermal characterizations were carried out by dynamic mechanical analysis, thermo-gravimetric analysis, and thermo-mechanical analysis tests. Results showed that the 2 wt% nanoclay loading is optimum in terms of moisture barrier capability, compression, and thermal properties. After 90-day exposure to seawater, the 2 wt% nanophased composite absorbed 0.39% moisture compared to 0.67% moisture absorption by the base carbon/epoxy composite. Compressive strength and modulus were decreased by 8.20% and 7.11% respectively, for 2 wt% nanophased composites submerged in seawater for 180 days compared with identical samples with no exposure to seawater. Corresponding data from thermal characterization tests indicate storage modulus and glass transition temperature to be 6.59% and 6.1 °C lower respectively, and the coefficient of thermal expansion to be increased by about 6% for the 2 wt% conditioned sample. SEM study revealed that the nanophased composites exhibited a better bonding between the fiber and matrix compared to the base one even after exposure in the seawater. It is concluded that the excellent barrier capacity, higher surface area, and high aspect ratio of nanoclay are responsible for enhanced durability of the nanophased carbon/epoxy composite in seawater compared to the base one in the same condition.

Carbon nanotube – Carbon fiber reinforced polymer composites with extended fatigue life

In this study, uniform and patterned multiwall carbon nanotubes (MWCNTs) forests were grown over carbon fiber fabrics utilizing a relatively non-destructive synthesis technique; graphitic structures by design (GSD). Carbon fiber reinforced epoxy polymer composites (CFRPs) were fabricated based on the carbon fibers with surface grown MWCNTs and examined under monotonic tensile tests. The fabricated composites were also examined under a tension-tension fatigue loading at three stress levels of 85, 90 and 95% of their monotonic strength using a cyclic stress ratio of 0.10 to investigate the effects of the various topologies of the surface grown MWCNTs on the fatigue damage progression and life of the CFRPs. Results revealed that the fatigue life of the CFRPs with patterned growth of MWCNTs exhibited a significant fatigue life improvement of 150%. The fractography analysis elucidated the role of MWCNTs in protecting the fiber yarn against the matrix cracks leading to significant fatigue life improvement.

Optimization of flexural strength of CFRP hybrid nano composites containing nanoZnO and nanoclay particles

The utilization of nanoparticles for alteration of epoxy matrix has results in improved mechanical properties of the CFRP composites. The aim of this study is to investigate the influence of nanoparticles like ZnO and montmorillonite nano clay and fiber angle of orientation on the flexural strength of carbon fiber reinforced epoxy polymer composites. In this experimental study, weight percentage of nanoZnO and nano clay and also fiber angle of orientation have been chosen as variables that are independent and the effect of all these variables on the flexural strength of hybrid CFRP laminate composite has been investigated. These experiments were done by using. Central composite design, the part of response surface design method, which has been used to present mathematical expressions as function of physical factors to wear behavior prediction of new hybrid nano composite and also used to present a mathematical model as to reach the optimum design of new hybrid nano composite. The total twenty experiments were designed with six replicates at center point by using MATLAB and the prepared samples were tested for the flexural behaviour. The maximum and minimum value of flexural strength were 932.87 MPa and 53.32 MPa which occurred in design levels 2 and 19 respectively and also optimization was carried out optimizer of Minitab software. The optimization results shows that the best flexural strength got from the software was 1298.1 MPa which observed at 1.3 wt% of nanoclay, 4.8 wt% of nanoZnO and 10° of fiber angle of orientation and experimental value of flexural strength was obtained 1095.23 MPa. For optimum range of variables.

Dynamic properties of hybrid composite structures based multiwalled carbon nanotubes

The present paper investigates an experimental approach concerning the determination of dynamic behavior and damage kinetics of composite materials based on multiwalled carbon nanotubes (MWCNTs), embedded in electrospun reactive nanofibers in the Taylor impact test. Different impact energies have been considered namely; 21J and 39J to investigate the composite response. Projectiles are manufactured from a commercial steel 2071 with a nominal diameter of 50 mm and 1600 g of weight. The projectile was fired against a composite specimen initially hooked on a cell effort by a compressed gas gun within the velocity of 5 m/s and 7 m/s. Three types of specimens are considered: (1) MAT1 (carbon fiber reinforced epoxy polymer composite), MAT2 (consists of MAT1 and electrospun Polybenzmideazole-Bismaleimide (PBI-BMI) nanofibermats between carbon fiber layers) and MAT3 (consists of MAT2, where PBI-BMI nanofibermats are reinforced with multiwalled carbon nanotubes (MWCNTs)). The effect of the MWCNTs on the dynamic properties of the composite structures was studied. Microscope observations reveal damage progressive, buckling and crush-front propagation during tests. Application of the PBI-BMI reactive nanofibermats reinforced with MWCNTs leads to damage prevention, reducing damage area in composite samples.

Nanoscale toughening of carbon fiber reinforced/epoxy polymer composites (CFRPs) using a triblock copolymer

This work explored the incorporation of a triblock copolymer in carbon fiber reinforced epoxy polymer composites (CFRPs) to improve their mode-I fracture toughness, GIc (J/m2). The triblock copolymer poly (styrene)-block-poly (butadiene)-block-poly (methylmethacrylate) (SBM) was used to modify the CFRP matrix at 5, 10 and 15 phr concentrations, respectively. CFRPs were manufactured using an in-house sizing tower system, prepregger, vacuum bag and autoclave method. Mode-I fracture toughness testing revealed a 290% increase in GIc by incorporation of the reactive sizing on the fibers and 10 phr SBM in the matrix. Scanning electron microscopy of the SBM modified CFRP fracture surfaces showed that well distributed, sub 100 nm spherical micelles of SBM underwent cavitation and induced void growth and shear yielding toughening mechanisms to absorb fracture energy. It is noteworthy that longitudinal and transverse composite three point flexural testing showed that the SBM modified matrix did not decrease CFRP strength and stiffness up to 10 phr additive. Further, dynamic mechanical analysis revealed that SBM at 10 phr decreased the glass transition temperature (Tg) of CFRPs by only 2.9 °C; the Tg was then recovered at 15 phr SBM. Finally, the SBM modified CFRP GIc was compared to the neat matrix GIc at 0, 5, 10 and 15 phr SBM to develop a ‘transfer factor’ for SBM modified composites. It was found that only 10% of the increased matrix toughness was transferred from the SBM modified epoxy to the CFRPs. The presence of the rigid carbon fibers constrains plastic deformation of the modified epoxy and limits the toughness transfer in the composite.

Effects of Homogeneous Low Energy Electron Beam Irradiation (HLEBI) on Adhesive Force of Peeling of Carbon Fiber Reinforced Epoxy Polymer (CFRP) and Polytetrafluoroethylene (PTFE)

Effects of Homogeneous Low Energy Electron Beam Irradiation (HLEBI) on Adhesive Force of Peeling of Carbon Fiber Reinforced Epoxy Polymer (CFRP) and Polytetrafluoroethylene (PTFE)

Impact behavior and damage characteristics of hygrothermally conditioned carbon epoxy composite laminates

A novel finding about effects of moisture and cyclic hygrothermal conditions on the impact resistance of carbon fiber reinforced epoxy polymer (CFRP) composites are presented. The course of experiments began with the fabrication of specimens using unidirectional CFRP prepreg materials. As-fabricated specimens were exposed to two types of hygrothermal conditions which were designed to simulate in-service environment. Microstructure characterization of the specimens revealed that neither hygrothermal conditions brought about any evident defects to the laminates. Low-velocity impact testing was then carried out on the specimens with different moisture levels. It was found for the first time that moisture significantly alleviated impact induced damage in the CFRP unidirectional laminates. Detailed discussion about how the absorbed moisture influenced the impact behavior of the laminate was carried out based on the interpretation of the damage characteristics and impact testing data. The effects of absorbed moisture on the GIC of this material were explored to assist the understanding of the role played by the absorbed moisture during low-velocity impact testing.

A comparison of chemical and atmospheric plasma assisted copper plating on carbon fiber reinforced epoxy polymer surfaces

In the present study a comparison of two different surface pre-treatments and their influence on a subsequent surface metallization were studied. Standard electroless copper deposition involving initial etching in mild acid is thoroughly compared with the process where plasma pre-treatment replaced the mild acid etch. Specific surface co-planar type of dielectric barrier discharge was employed to provide a technologically feasible plasma pre-treatment of composites of carbon reinforced epoxy polymers. Results demonstrated both approaches being able to achieve excellent adhesion of final coating. In contrast to standard chemical pre-treatment, plasma pre-treatment is associated with changes of initial composite surface chemistry only. The purpose of plasma action in polymer pre-treatment is to provide ample amount of active surface sites where Pd ions can be attached effectively. XPS analysis revealed, that Pd atom on plasma treated surface takes the form of its oxide compounds PdO and PdO2 preferably, while its form on the surface of standard chemical pre-treatment is mostly metallic-Pd.

Effects of Tensile Prestress Level on Impact Value of 50 vol% Continuous Unidirectional 0 Degree Oriented Carbon Fiber Reinforced Epoxy Polymer (CFRP)

Effects of tensile prestress level on Charpy impact value (auc) of 50vol% continuous unidirectional 0 degree oriented carbon fiber reinforced epoxy polymer (CFRP) were investigated. Experimental results showed the auc at mid-fracture probability Pf = 0.50 induced by a large prestress of 17.6MPa (109kJm ¹2 ) was increased 30% over that (84kJm ¹2 ) of slight prestress of 0.25MPa. The statistically lowest impact value as at Pf = 0 calculated by 3-parameter Weibull equation was raised 26% from 73 to 92kJm ¹2 showing increased reliability of part strength. Fracture surface observation showed a flat surface extending through the thickness from the impact side generally extends deeper as prestress level was raised. This may be due to the transition depth in the specimen thickness from compression to tension is deeper during impact as prestress level was increased acting to raise the impact values. [doi:10.2320/matertrans.M2013278]

Impact Value of CFRP/Ti Joint Reinforced by Nickel Coated Carbon Fiber

A nickel coated carbon fiber reinforced joint (Ti/NiCF/CFRP) was suggested and developed between carbon fiber reinforced epoxy polymer (CFRP) and titanium (Ti). The most important point of the new joint method are not only extremely large friction force by broad interface of carbon fiber with 6µm-diameter, but also Ni-coating for suppression of TiC formation and enhancement of contact ability of fiber wrapped by molten Ti. The new joint part was strengthened by impregnated nickel-coated carbon fiber (NiCF) and exhibited the high Charpy impact value (auc). Since carefulness for aircraft parts would be necessary, the lowest impact value (as) was defined. It was calculated by the 3-parameter Weibull equation when the fracture probability (Pf) = 0. The as of Ti/NiCF/CFRP was 2.2kJm ¹2 , which was higher than that (0.34kJm ¹2 ) of the joint sample with glue. Consequently, the new joint method remarkably enhanced the safety level (reliability). [doi:10.2320/matertrans.M2013320]

Charpy Impact Value of Sandwich Structural (CFRP/ABS/CFRP) Composites Constructed with Carbon Fiber Reinforced Epoxy Polymer (CFRP) and Acrylonitrile Butadiene Styrene (ABS) Sheets Separately Irradiated by Electron Beam Prior to Lamination

Experimental results showed homogeneous 100keV-class low voltage electron beam irradiation (HLEBI) prior to lamination assembly (our new method) often improved the Charpy impact values (auc) of the sandwich structural CFRP/ABS/CFRP (carbon fiber reinforced epoxy polymer) and (acrylonitrile butadiene styrene) with low volume fraction of carbon fibers for cost reduction and safety. The auc values at each Pf of CFRP/ABS/CFRP laminated by both high-strength and light structural CFRP plies and ABS core separately irradiated from 0.04 to 0.30MGy-HLEBI before lamination were mostly higher than that without HLEBI. Although carefulness for aircraft parts would be necessary since higher doses of 0.30 and 0.43MGy HLEBI applied to the CFRP sheets and ABS core before lamination assembly reduced the lowest impact value at Pf = 0( as) calculated by 3-parameter Weibull equation, the low dose of 0.04MGy-HLEBI before lamination assembly apparently boosted the as almost 3 times, ³200%, over the untreated samples from 15 to 44kJm ¹2 . Moreover, applying the low dose of 0.04MGy-HLEBI before instead of after lamination apparently improved the as 76% from 25 to 44kJm ¹2 . Furthermore, applying the medium doses of 0.13MGy or 0.22MGy HLEBI before rather than after lamination appeared to improve the as remarkably from 0 to 40, and 0 to 42kJm ¹2 , respectively. The new method of applying HLEBI prior to lamination allows for more efficient beam contact to the inner core and its surface permitting deeper areas in thick laminated composites such as CFRP/ABS/CFRP to be treated generating dangling bonds, hence strengthening the bulk materials and the CFRP-ABS interface of the thick laminated CFRP/ABS/CFRP constructed with thin or thick surface sheet and thick core can be expected. [doi:10.2320/matertrans.MBW201209]

J045023 巨大比表面積炭素繊維を用いた異種材料接合([J045-02]知的材料・構造システム(2))

A new method with extremely large friction force by broad interface of carbon fiber (CF : 6μm diameter) coated by nickel (Ni) to prevent TiC formation and to enhance the ability of fiber rapping by molten Ti have been suggested for a joint (Ti/NiCF/CFRP) of carbon fiber reinforced epoxy polymer (CFRP) and titanium (Ti). The new joint part was strengthened by impregnated nickel-coated carbon fiber (NiCF) exhibited the high Charpy impact value (a_<uc>). Results showed overall, the Ti/NiCF/CFRP had higher a_<uc> than the Ti/Glue/Epoxy and Ti/Epoxy at each fracture probability (Pf). Based on the SEM and XRD pattern results, the chemical compound of TiC has not been observed in the Ti/NiCF/CFRP sample. Therefore, we concludes that the Ni coating prevents the formation of TiC in the of the Ti/NiCF/CFRP joint sample. Since molten titanium does not bite the carbon fiber, the Ni coated carbon fiber exhibits to maintain the high strength.