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Abstract In this study, a sandwich composite structure was fabricated with core syntactic foam composites (SFC) reinforced with face-sheets of combined kenaf and glass fibers. The core SFC was made from hollow glass microsphere (HGM)/epoxy resin mixture. The focus of this study is to design a suitable material for marine, automobile, and structural applications by investigating the water absorption capacity, hardness, buoyancy, and acoustic resistance level of the sandwich composite. Four sequences of face-sheet reinforcement [e.g. kenaf-kenaf(KK); glass-glass(GG); glass-kenaf(GK), and kenaf-glass(KG)] were adopted. The results show that the KK sandwich absorbed more water, with buoyancy level of 0.329% than other sequence. GK shows the highest sandwich in hardness strength with 58Hv, and 35% more than the KK, while there was no significant difference in the sound pressure level of the sandwich composite.

Abstract Natural resource-driven approaches to bioengineering plastics are being developed to compete in the automobiles, power, and other sectors. Polytrimethylene terephthalate (PTT) is a particular of them, and it was chosen for the current investigation to build an advanced nanocomposite material. Using a twin-screw micro compounder, injection moulded PTT/Graphene-Oxide (GO)/Carboxyl functionalized Multiwall Carbon nanotube (f-MWCNT) hybrid nanocomposites were prepared. The impact of GO and f-MWCNT reinforcement on the composite’s thermal and mechanical characteristics of hybrid nanocomposites was examined. GO was synthesized from the graphite powder by modified Hummer’s method and MWCNTs were functionalized using the concentrated sulfuric acid (H2SO4) and nitric acid (HNO3) with a volume ratio of 3:1 in an ultrasonic bath at room temperature. In all formulations, the investigation was done at a constant filler amount of 2 wt%. To understand the chemical interaction between PTT and nanofiller, Raman spectroscopy was used and to examine the state of dispersion, scanning electron microscopy (SEM) was systematically analysed. In comparison to pristine PTT, the water absorption, tensile strength, flexural strength and impact strength of hybrid nanocomposites were improved marginally. It was also observed that GO has more prominent in increasing the mechanical properties of the hybrid and f-MWCNT in thermal properties. The 3-D geometrical bridge between GO (2-D) and f-MWCNT (1-D) made the hybrid more dispersible and effective for different applications.

Abstract High‐density polyethylene (HDPE) polymer is one of the largest contributors to plastic wastes causing detrimental effects on various sectors of society, and is not biodegradable in nature. In the first stage, river sand and a recycled HDPE as a binder were used to manufacture eco‐friendly plastic sand bricks with various sand(s):plastic(p) ratios: 60s:40p; 65s:35p; 70s:30p; 75s:25p; 80s:20p; 85s:15p. In the second stage, 1%, 5%, and 10% of Kaolin Clay was added to each ratio of sand:plastic, respectively. Three mechanical tests were conducted: compressive strength, impact, and short beam strength. First, the addition of 5% Kaolin Clay to 75s:25p ratio increased compressive strength significantly from 21.4 to 52.76 MPa. Second, the addition of 10% Kaolin Clay in the ratio of 75s:25p mixture increased the impact strength from 4.8 to 5 J. Finally, the addition of 5% Kaolin Clay in the ratio of 60s:40p mixture increased the short beam strength significantly from 1.84 to 2.27 MPa. SEM analysis showed a well‐compacted interface indicating effective bonding between the HDPE and river sand particles in the 75s:25p ratio. Hence, the results of this study present a potential for the use of recycled HDPE plastic to manufacture plastic sand bricks. Highlights Addition of Kaolin Clay improved the mechanical properties of the composite material.

Biobased biodegradable materials are gaining popularity with increasing public awareness on the negative impacts of conventional plastics on the environment. There is, however, a lack of promising biobased materials suitable for various end-use applications that are also environmentally safe. Recently, banana sap and banana fibres have been explored as a potential source of organic material as they are abundant, cost-efficient, and environmentally friendly. In this study, two hybrid bioresins (1) banana sap maleate (BSM) and (2) banana sap maleate + banana fibre (BSMF) were developed, and their material properties and environmental suitability were examined by analysing their physicochemical characterisation and biodegradation testing. We used thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy for the physicochemical characterisation of BSMF before and after composting and measured carbon dioxide evolved during the biodegradation to calculate biodegradability. SEM analysis also showed a significant disintegration and surface degradation in BSMF compared to BSM and other control materials such as control resin and cellulose. CO2 mineralization results indicated a potential microbial bioassimilation of the materials under composting conditions. Biodegradability of the BSMF composite, as indicated by CO2 emission, was 17.6% higher than BSM and other control materials used in this study. The present study provides crucial evidence that the reinforcement of banana fibre into banana sap bioresin composite can significantly improve material properties and enhance biodegradability in the composting conditions. These results are quite promising as they show that, with some tweaking; natural materials can reduce environmental impact of composites and improve material properties for different end-use applications and involves less exploitation of nonrenewable resources for polymer production. This study also provides an avenue to consider BSMF for carrying out our future life cycle assessment (LCA) and to compare with commercial product’s LCA. In a circular economy approach, characteristics such as durability, environmental toxicity, and recyclability of such materials should be studied and optimised to reduce energy consumption and environmental impact.

This study focuses on the fabrication and analysis of the mechanical behaviour of unidirectional (UD) glass fibre-reinforced polymer (GFRP) facesheet and polyvinyl chloride (PVC) foam core sandwich structures fabricated by a vacuum-assisted resin infusion method (VARIM). These sandwich structures are commonly used in marine and wind turbine blade applications. To date, relatively little knowledge about the functional behaviour of UD GFRP compared to composites reinforced with bidirectional mats is available for day-to-day applications. The effects of the facesheet orientation, facesheet thickness, and core thickness on the mechanical behaviour of the specimens were examined. The UD fibres were oriented in cross-ply (0/90), angle-ply (+45/−45), and quasi-isotropic orientations. Various mechanical properties such as tensile, flexural, flatwise compression, and edgewise compression tests were examined. Characterization of the tensile properties of the facesheet showed that the cross-ply orientation had a higher strength than the angle-ply and quasi-isotropic orientations. The flexural load-carrying capacity of the cross-ply facesheet orientation was superior to the other orientations. The increase in the core thickness changed the flexural failure mode from face yield and core shear to core indentation. Flatwise compression (FWC) was tested to determine the core characteristics of the sandwich structure, and the peak loads of 4.90, 1.81, and 3.90 kN were obtained for 10-, 15-, and 20 mm core thicknesses, respectively. Edgewise compression (EWC) exhibited stable end crushing for thinner facesheet, whereas thicker facesheet showed core crushing and buckling. When the facesheet thickness was increased from 1.5 mm to 3 mm in the EWC, the buckling load increase ranged from 2.53% to 44.83% for core thicknesses 10-, 15-, and 20 mm, respectively.

The objective of this work is to improve the thermal properties of natural fibers by infusing thermally stable alumina-silicate clay nanoparticle into the fibers by physical infusion method. Four commonly used natural fibers were selected, namely, banana, coir, kenaf, and sisal fibers. Nanoclay particles were infused into these fibers at untreated and mercerized (NaOH-treated) stages. The distribution of nanoclay on fiber surface is examined by using scanning electron microscope (SEM). Nanoclay distribution is better in NaOH-treated fiber when compared with untreated fiber. Thermal properties such as mass loss, thermal decomposition, and flame retardance was evaluated for all fiber series. Thermal degradation kinetics of untreated and treated fiber series is examined by using Coats-Redfern method. The outcome of the result shows that the thermal properties of nanoclay infusion in NaOH-treated fibers are fairly consistent across all types of tested fibers. Nanoclay infusion into the fibers improved mass gain, decomposition, and flame retardance properties.

There has been extensive research on improving and innovating current treatments for irritable-bowel-syndrome using nanotechnology. However, there are growing challenges to progress these drugs to clinical trials and commercialisation. This study sought to develop a framework to manage key features, overlooked in current studies, to improve the development of drugs. An integrative literature review was used to extract themes by using a summative content analysis to interrogate information. Validity was established when saturation of information was achieved. Reliability focussed on the repeatability of key information. Absorption, distribution, metabolism, excretion and toxicity, quality by design attributes, metrology, and standardisation of practice emerged as important themes. These themes together among others, were used to develop the framework to manage the drug development process: Knowledge-based society, Foresight planning, Multidisciplinary approach, Unified definition, Adapt to existing standards and guidelines, Precautionary principle, Case-by-case approach, Quality-by-design, Scale-up and Training. The framework provided reflections that no study has considered. The framework will ensure that drug development will be approached strategically to avoid duplication of research-designs, including risk mitigation, quality at the source and supplier-chain management to progress drug development to clinical trials and beyond.

Recent advances in polymer nanocomposites open a wide range of applications in various industrial sectors. Due to their high potential properties, these materials are replacing the usage of metals for many heavier components in automobile industries. In this experimental work, the tribological performance of Graphene oxide (GO) - Polyamide is investigated against pristine polyamide by fabricating gears for the usage in engineering applications. A gear test rig was developed in-house for analysis to study the specific wear rate and temperature gradient at different conditions of load and speeds. The wear resistance of the polyamide gears with the addition of 0.03wt.% of graphene oxide is better than the pristine polyamide gears and the specific wear rate is reduced significantly. The reduced specific wear rate of these polymer nanocomposite gears is attributed to the superior properties of graphene oxide such as High specific surface area, good adhesion properties and enhanced glass transition temperatures. The GO nanocomposite gear seems to be a potential alternative against conventional gears for engineering applications. Finally, the wear mechanisms and the potential of GO-based polyamide nanocomposite gears were proposed tentatively in the development of transmission gears for engineering applications. [ABSTRACT FROM AUTHOR]

The compressive response of cross-linked and linear PVC foam core materials, namely, H130 and HD130 having identical densities were evaluated. Both cores were subjected to compressive loading at various strain rates ranging from quasi-static to 1560 s1. At quasi-static loading, the compressive strength of the H grade was approximately 30% higher than the HD grade. On the other hand, at HSR loading the HD grade was 20% higher. HSR tests were also conducted at various temperatures ranging from 25 to 12°C. It was observed that degradation of strength was more severe for the HD grade as temperatures increased. A recovery of the cores original volume was also noticed during high strain rate and elevated temperature tests. Accordingly, residual properties were determined. Results show that only the residual properties of the HD grade were affected by temperature. [ABSTRACT FROM AUTHOR]

When a sandwich structure is subjected to transverse loads, the face sheets carry bending moments as tensile and compressive stresses and the core carries transverse forces as shear stresses. The core is typically the weakest component of the structure and is the first to fail in shear. In this study the shear fatigue behavior of two closed-cell cellular PVC foams, Divinycell HD130 (linear) and H130 (cross linked), with the same nominal density of 130 kg/m3, were investigated. Static shear tests reveal that HD130 foams are more ductile, have almost twice the energy absorption capability, and an extraordinary crack propagation resistance when compared to the H130 foams. Shear fatigue tests were conducted at room temperature, at a frequency of 3 Hz and at a stress ratio, R = 0.1 on the HD130 and H130 foams. S-N curves were generated and shear fatigue characteristics were determined. The number of cycles to failure for the linear foams was substantially higher than that of the cross-linked PVC foams. HD foams have smaller cells with thicker faces and edges. This microstructure supports absorption of larger amounts of liquid resin forming a resin rich sub interface zone just below the actual core skin interface. The high intrinsic toughness of the sub interface delays the initiation of fatigue cracks and thereby increases the fatigue life of the HD foams. For both foams, shear deformation occurs without volume change and the materials fail by shearing in the vicinity of the centerline of the specimen along the longitudinal axis. In both cases numerous 45° shear cracks form across the width of the specimen and are equidistantly spaced along the length of the specimen. The occurrence of these through the thickness shear cracks signals the final failure event during fatigue. Details of the experimental investigation and the evaluation of the fatigue performance are presented. [ABSTRACT FROM AUTHOR]