Water absorption associated with gamma irradiation on kevlar/oil palm EFB hybrid composites

The objective of this work is to analyse the water absorption behaviour on the gamma irradiated Kevlar/Oil Palm EFB hybrid composites. The hybrid composites were fabricated through manual hand lay-up method. Different layering sequence of hybrid composites were fabricated which is Oil Palm EFB/Kevlar/ Oil Palm EFB (OP/K/OP) and Kevlar/Oil Palm EFB/Kevlar (K/OP/K). Various Gamma radiationdoses;25 kGy, 50kGy and 150 kGy were exposed to the composites. The results showed that for both layering pattern, the water absorption for non-irradiated hybrid composites absorbed more water than irradiated hybrid composites. Water uptake for non-irradiated K/OP/K is 51% and with radiation is 21% at 50 kGy. Hybrid OP/K/OP that is not irradiated absorbed less water which is 27% as compared to the same hybrid but with radiation only 17%of water being absorbed at 50 kGy. The results showed that irradiated hybrid composites absorb less water compared to non-irradiated hybrid composites. This suggest that crosslinking took place due to the radiation. This implies that with radiation of certain dose could improves the properties of water absorption forKevlar/ Oil Palm EFB hybrid composites

Effects of layering sequence and gamma radiation on mechanical properties and morphology of Kevlar/oil palm EFB/epoxy hybrid composites

The present study evaluates the tensile and flexural properties, including the morphological features of gamma radiated Kevlar/oil palm empty fruit bunch (EFB)/epoxy hybrid composites fabricated using hand lay-up method with different layering sequences. The fabricated hybrid composites were exposed to different gamma radiation doses: 25 kGy, 50 kGy and 150 kGy. Mechanical (tensile and flexural) and morphological properties were evaluated by using universal testing machine and scanning electron microscopy, respectively. Results obtained indicated that tensile strength of hybrid composites were effected by layering sequence. The layering sequence involving the use of EFB as core material yielded better mechanical performance compared to the layering pattern when Kevlar served as the core material. The tensile and flexural properties of hybrid composites showed an improvement for irradiated samples at a low radiation level. Hybrid composites displayed decrease in tensile strength at 50 kGy whereas flexural strength still showed an improvement. However, at 150 kGy, the tensile and flexural properties exhibited significant degradation. FESEM of tensile fracture composites showed the exist of fibre pull out and voids. However, at 150 kV bigger and ruptured voids were observed. It can be concluded from this finding that mechanical performance of Kevlar/EFB/Kevlar hybrid composites after Gamma radiation, has made it as promising material for automotive, aerospace and construction applications

Gamma-ray attenuation coefficients of carbon steel plates using iridium-192 / Siti Madiha Muhammad Amir

Measurement of gamma radiation attenuation coefficients on carbon steel using gamma radiation beam from Iridium-192 has been made to permit their use for precision measurement, material studies and in various industrial radiographic techniques. The material examined is carbon steel plates with various thicknesses ranging from 2 mm to 13 mm. There are two aspects in this study; determination of the attenuation coefficient using theoretical method, and from experiments. Two types of detectors are used; the film radiography and ion chamber. The gamma ray source is the polychromatic radionuclide Iridium-192. Cross section of the incoherent scattering of every element in the carbon steel material sample has been calculated using the Klein-Nishina formula incorporating the structure function correction. We integrate the Klein-Nishina formula using the Gauss-Legendre quadrature and the cross section agrees very well with the published results. The cross section of the incoherent scattering is used to calculate the theoretical effective linear attenuation coefficient and is found to be 0.231. The effective linear attenuation coefficient value from the two experiments has the value of 0.3401cm−1mm− as determined from the transmission curves which is consistent with the theoretical value

Characterization of low velocity impact damage of gamma-irradiated kevlar/oil palm empty fruit bunch hybrid composites

Malaysia, the second world largest exporter of palm oil has generated abundance of oil palm empty fruit bunch (EFB) waste. The oil palm EFB has the potential as the reinforcement in composites for energy absorption applications. In this work, the oil palm EFB were hybridized with Kevlar fabric using hand lay-up technique with different layering patterns. The composites were exposed to gamma radiation dose, i.e. 25 kGy, 50 kGy and 150 kGy. Material characterization were carried out to evaluate the effects of radiation on its mechanical and physical properties of the materials. Low velocity impact and compression after impact tests were performed in this study. Damage propagation were observed using Ultrasonic C-Scan, Computed Thermography and Acoustic Emission methods. The tensile and flexural showed that hybrid composites were 48% and 45% respectively higher in hybrid composites with Kevlar as the skin. The compressive strength was 69% for hybrid composites with oil palm EFB as the skin. The optimum dose for tensile was at 25 kGy and 50 kGy for flexural and compression. At 150 kGy, the degradation of mechanical properties were observed. The density of hybrid composites for Kevlar as the skin was 0.89 g/cm³. Irradiated composites were observed to have lower water absorption capacity. The impact resistance of the irradiated Kevlar/oil palm EFB hybrid composites was up to 35 J. In damage detection, the images from ultrasonic-C-Scan method did not reflect the actual images observed. Computed tomography and acoustic emission complemented each other in detecting the matrix cracking, delamination and fibre breakage damages in the hybrid composites. From the compression after impact test, it was observed that the compressive residual strength was decreased when the impact energy increased. The optimum radiation dose to withstand the compressive residual strength for 35 J was at 50 kGy. The newly developed hybrid Kevlar/oil palm EFB composites have the potential to be used in energy absorption applications and exposure to gamma radiation is one of the methods to improve its mechanical strength of the hybrid materials for monotonic loading applications

Failure Analysis of Plant Fibre-Reinforced Composite in Civil Building Materials Using Non-Destructive Testing Methods: Current and Future Trend

Natural plant fiber-reinforced composite (NFC) has become a preferred component in modern-day civil building construction materials because it offers, among others, an environment-friendly solution without compromising stringent engineering requirements. Such green-based composites have exhibited noteworthy level of competitiveness comparable to that of the existing commercially available nongreen materials. Furthermore, NFC can also be tailored to align with the desired functional attributes. However, lack of comprehensive guidelines and recommended applications of suitable methods to assess composite failure of such novel NFC have raised significant concerns. This paper provides a comprehensive review of the latest developments in nondestructive testing (NDT) that can be applied to investigate into NFC failures. The study further explores alternative nondestructive testing methods and technologies exhibiting potential use in plant fiber composites studies, hence paving the way to future investigation trends. Precise characterization of defects and identification of damages in NFCs present a major challenge, demanding application of advanced nondestructive testing (NDT) methodologies accompanied with expert interpretation. Findings in this review can be applied to identify and explore new areas of research to analyze failure modes and fractures in NFC by applying NDT or by integrating NDT with other advanced technologies including machine learning

Low velocity impact analysis of pineapple leaf fiber (PALF) hybrid composites

The low-velocity impact behaviour of pineapple leaf fiber, PALF reinforce epoxy composite (P), PALF hybrid (GPG), and four-layer woven glass fiber (GGGG) composite was investigated. As for post-impact analysis, the damage evaluation was assessed through photographic images and X-ray computed tomography, using CT scan techniques. The key findings from this study are that a positive hybrid effect of PALF as a reinforcement was seen where the GPG shows the delayed time taken for damage initiation and propagation through the whole sample compared to GGGG. This clearly shows that the addition of fibers does have comparable composite properties with a fully synthetic composite. Through the visual inspection captured by photographic image, the presence of woven fiber glass mat in GPG presents a different damage mode compared to P. Moreover, CT scan results show extended internal damage at the cross-section of all impacted composite

Low-Velocity Impact Analysis of Pineapple Leaf Fiber (PALF) Hybrid Composites

The low-velocity impact behaviour of pineapple leaf fiber, PALF reinforce epoxy composite (P), PALF hybrid (GPG), and four-layer woven glass fiber (GGGG) composite was investigated. As for post-impact analysis, the damage evaluation was assessed through photographic images and X-ray computed tomography, using CT scan techniques. The key findings from this study are that a positive hybrid effect of PALF as a reinforcement was seen where the GPG shows the delayed time taken for damage initiation and propagation through the whole sample compared to GGGG. This clearly shows that the addition of fibers does have comparable composite properties with a fully synthetic composite. Through the visual inspection captured by photographic image, the presence of woven fiber glass mat in GPG presents a different damage mode compared to P. Moreover, CT scan results show extended internal damage at the cross-section of all impacted composite

Low velocity impact and compression after impact properties on gamma irradiated Kevlar/oil palm empty fruit bunch hybrid composites

This work investigates the dynamic impact response of Kevlar/oil palm empty fruit bunch (EFB) hybrid composite structures with/without gamma radiation under low velocity impact (LVI) and compression after impact (CAI) test. The layering pattern Kevlar/oil palm EFB/Kevlar (K/OP/K) was applied in this work. Irradiation with gamma ray with various doses were applied from 25–150 kGy. LVI results shows that hybrid Kevlar/oil palm EFBs (Kevlar/OPEFB) that were not irradiated have greater impact resistance as compared to irradiated hybrid Kevlar/OPEFB. It was also observed that the hybridization of Kevlar/OPEFB with gamma irradiation helped to improve the compressive residual strength of the composites. It was found that Kevlar/OPEFB hybrid composites with the layering sequence K/OP/K can withstand up to 35 J of impact energy, with the optimum gamma radiation dose at 50 kGy

Nanoclay effect on the ablative behaviour of glass fiber reinforced polymer and glass fiber reinforced geopolymer nanocomposite using radiography

The addition of nanoscale additives to polymers can increase their thermal resistance, making them suitable for a variety of engineering applications. In this investigation, nondestructive testing (NDT) was performed to observe the composite's post-fire test behaviour. This study investigated the ablative behaviour of glass fibre-reinforced epoxy and geopolymer with varying nanoclay concentrations. Additionally, after firing all of the samples, the thermal defects were evaluated with Infrared thermography method, Digital Detector Array (DDA) Radiography method. According to the ablation analysis, increasing the nanoclay concentration in nanocomposites was found to increase the samples' thermal ablation. In addition, geopolymer nanocomposite exhibited superior ablative behaviour compared to epoxy nanocomposite, with a back surface temperature of 51.34 °C compared to 176.86 °C for 7 wt nanoclay in epoxy nanocomposite. DDA analysis revealed that the nanocomposite surface structure contains fewer voids when a higher proportion of nanoclay is employed