Search

Composite laminate design is an important procedure in defining the mechanical properties of laminated composite structure to be used in multi-directional service loading application. Composite technologies or manufacturers who is lack of knowledge regarding the importance of laminate design, tend to develop a composite structure that will collapse or fail below the service requirement. The purpose of this study is to determine the effect of fiber orientation on flexural properties of the designed glass fiber reinforced epoxy laminated composite. Six sets of laminates with different fiber orientation and sequence were simulated using CompositeStar© software to determine its flexural properties. Samples were fabricated to verify the simulated data and were tested in accordance to ASTM D2344. Moreover, crack pattern within the samples after the flexural test is studied. From the simulated results, it shows that laminates which have fiber in tri-direction and quasi-direction display a higher flexural modulus and strength compared to laminates with fiber in uni-directional and bi-directional. In addition, data from tested fabricated laminates samples displayed the same modulus patterns against the simulated data, with variants from 8% to 35%. Additionally, it is found that samples with fiber in ±45 direction shows a transverse and shear cracking which prolonged the cracking propagation before the samples show a complete failure.

In this study, thermoplastic elastomer nanocomposites based on linear low density polyethylene (LLDPE)/silicone rubber (SR; 90:10) filled with a 2 vol% boron nitride (BN) nanofiller were exposed to electron beam (EB) irradiation at low irradiation doses (20, 40, 50, and 100 kGy). The response of the LLDPE/SR/BN nanocomposites to the EB irradiation crosslinking was examined and compared with the non-irradiated samples in terms of dielectric properties (permittivity and loss tangent), dielectric breakdown strength, morphology, and rheological properties. A swelling study was performed to quantify the degree of crosslinking and it was found that the crosslink density increased slightly upon EB irradiation. Scanning electron microscopy results provided evidence that the SR phase was selectively crosslinked and interfacial adhesion was improved in irradiated samples. A good correlation was observed between the morphology and the dynamic storage modulus obtained from the melt rheological experiments. The optimum irradiation dose was found to be 20 kGy, which was marked by an improved dielectric breakdown strength, a permittivity-frequency curve plateau and a reduced loss tangent value. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

This study determines the applicability of nanofillers (silica, boron nitride, and zinc oxide) in linear low-density polyethylene (LLDPE)/silicone rubber (SR) insulation compounds. Design of experiment is adopted to model the relationship between the properties (permittivity, loss tangent, dielectric strength, and volume resistivity) and factors (SR content, type of nanofiller, and nanofiller loading) for performance optimization. It is observed that SR content and type of nanofiller significantly influence the electrical properties of LLDPE/SR nanocomposites. Nanofiller loading, however, causes a small variation in the properties of the nanocomposites except for dielectric strength. From the optimization, it is found that the optimum formulation composition is 10 wt% of SR and 2 vol% of nanoboron nitride.

This study aims to determine the properties of waste betel nut husk (BNH) fiber as a potential alternative for reinforcement in polymer composites. The BNH fibres were subjected to alkali treatment using 5% sodium hydroxide. In this work, husk fibres extracted from betel nut fruit were characterized for its chemical composition, tensile properties, morphology, and interfacial shear strength. The cellulose content was increased with alkali treatment. Tensile strength and Young's modulus of BNH fibre dropped drastically with alkali treatment but with improvement in elongation at break of the fibre due to extraction of cementing materials of microfibrils in natural fibre, i.e. lignin and hemicellulose. SEM observations revealed that poor tensile strength and modulus were related to the cell wall thinning and deep pores in BNH fibre due to alkali treatment. Interfacial shear strength (IFSS) of alkali treated fibre was higher as compared to untreated BNH fibre due to the increase in fibre surface roughness with alkali treatment.

This study focused on the effects of maleic anhydride-grafted polypropylene (MAPP) on tensile, water absorption, and morphological properties of recycled newspaper (RNP) filled polypropylene (PP)/natural rubber (NR) composites. The abbreviation MAPP will be used for its common name in this research work. For both uncompatibilized and MAPP-compatibilized RNP-filled composites, tensile strength and elongation at break (EB) increased at certain filler content, then decreased at higher filler content. Meanwhile, continuous increase of Young’s modulus has been observed in the case of uncompatibilized and compatibilized composites. At similar filler content, compatibilized composites show higher tensile strength and Young’s modulus but lower EB than uncompatibilized composites. Water absorption study indicates that the incorporation of MAPP reduced water uptakes of the composites. This may be attributed to the enhanced adhesion between the MAPP-compatibilized RNP and polymer matrix, as evidenced from morphology study with scanning electron microscopy. The chemical interaction between MAPP-compatibilized RNP and polymer matrix was confirmed with Fourier transform infrared analysis.