Composites science and technology

Porous materials for sound absorption

The environmental problems associated with the production, disposal and recycling of synthetic fibre based polymer composites has prompted the development of eco-friendly natural fibres. It involves use of kenaf, jute, oil palm, cotton, flax, banana, hemp, sisal and pineapple leaf fibre (PALF) for various applications such as automotive, infrastructure, biomedical, furniture, packaging etc. PALF will be important in material development for structural and non structural industrial products with other natural and synthetic fibres with different matrix. This review paper deals with the mechanical properties evaluation of PALF and several factors influencing properties such as type of variety, fibre length, matrix type, fibre orientation, voids and porosity content. Recent research in the advancement of mechanical properties of PALF as reinforcement in thermoset, thermoplastic and biodegradable resins are briefly provided. Attempts have been made to characterize PALF as a hybrid composite with other natural and synthetic fibres. Surface treatments to improve the interfacial and interphasial PALF - matrix interaction with consideration of coupling agents for mechanical strength improving requirements are discussed. Along with limitations, technical solutions to the traditional problems of natural fibre composite processing, tensile properties improvement, durability, thermal stability and interfacial incompatibility enhancement are discussed. Overall, this review article investigates highlights and identifies gaps in the earlier research work. It provides the resourceful tabulated data for continuing future research in various streams with PALF as reinforcement.

Review on mechanical properties evaluation of pineapple leaf fibre (PALF) reinforced polymer composites

The year 2020 faced unprecedented challenge for most of the global economic growth due to the outbreak of Coronavirus disease (COVID-19). Despite a downward trend performance of the Malaysian oil palm industry, particularly for the first half of 2020, the impact is less severe due to the encouraging palm oil export revenue through the National Economic Recovery Plan (PENJANA) which nurtures a notable increase in crude palm oil (CPO) price. In honouring the Malaysian pledge on forest conservation, land expansion for the oil palm cultivation remains stagnant over the years. The effort is now shifting towards enhancing the oil palm yield performance through new planting materials and good agricultural practices, coupled with systematic pest and disease management. Sustainability continues to be the key agenda of the oil palm industry, in moving forward to sustain the industry ecosystem. The industry is now open for innovative palm oil processes to comply with the dynamic and stringent food safety and quality standards and trade regulations. Owing to the distinction in food and feed applicability together with health prospects, translating the information into consumer-friendly language is becoming crucial for effective communication. Valorisation via the concept of 'waste to wealth' has compelled series of innovations in capitalising oil palm co-products for greener bioenergy and oleochemicals, and source of phytonutrients to generate higher earnings without having to heavily rely on palm oil trade as commodity. Mandatory enactment of the Malaysian Sustainable Palm Oil (MSPO) certification scheme has portrayed a success story of showing the utmost commitment towards sustainability. With persistent dedication, the oil palm industry is envisaged to be self-sustaining, amidst the never-ending challenges surrounding economy, well-being and environment.

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Oil palm economic performance in malaysia and r&d progress in 2019

Building envelope insulation is crucial for an energy-efficient and comfortable indoor environment because the envelope accounts for 50–60% of total heat gain/loss in a building. Previous studies mostly used lifecycle cost as the criteria to select the optimum insulation materials with little or no consideration of embodied energy, emission, and summer overheating potential. This study presents a comparative analysis of building insulation materials properties (thermal, hygroscopic, acoustic, reaction to fire, environmental, and cost) and their performance in different climate zones and proposed an optimization framework. Insulation materials can be primarily categorized as conventional, state-of-the-art and sustainable. State-of-the-art insulation materials have the lowest thermal conductivity value amongst the three insulation types. However, their life cycle cost is higher compared to the other types. Sustainable insulation materials could be useful to delay and minimize indoor peak temperature and reduce overheating risk during the hot summer period. The analysis also showed that building walls with comparatively lower thermal resistance are more cost-effective for the cooling dominated region, but walls with higher thermal resistance are more cost-effective in heating-dominated regions. However, highly insulated and airtight houses may also lead to increased overheating risk and peak cooling demand during a hot summer period. In addition, hygroscopic, acoustic, and fire retardancy properties of insulation materials are critical to control indoor relative humidity in a humid region, to maintain a minimum noise level in a zone, and to reduce fire destruction. Hence, the optimization should include four criteria 1) Energy, 2) Environment, 3) Economic, and 4) Comfort.

Comparative analysis of building insulation material properties and performance

Background: Composite materials have steadily gained recognition worldwide for its uses in various sectors such as aerospace, infrastructures and automotive industries. Natural fibers are gaining recognition as a substitute to synthetic fibers due to its recyclability and abundance. Palm fiber reinforced polypropylene composite panels have potential to be stamp formed in order to build complex geometries. In stamp forming the most sensitive feature is elastic recovery during unloading. This phenomenon will affect the net dimension of the final product. Objective: To identify the effects of forming rate, tool radius, temperature and ratio of fiber to polypropylene on the spring-back of palm fiber composite. To deduce an empirical model in predicting spring-back. To investigate the effect of fiber composition on its tensile strength. Results: Statistical analysis conducted shows all the studied parameters gives significant effect towards spring-back. The higher the temperature, feed rate and fiber composition (up to 30wt %) the smaller the spring-back and it is vice versa for tool radius. An empirical model was formulated to predict the spring-back angle. 30wt% of fiber composition was found to give the highest tensile strength. Conclusion: The suggested temperature, fiber composition, tool radius and feed rate to get the smallest spring-back angle in the current study are 150 °C, 30wt%, 2mm and 500mm/min. While the fiber composition of 30wt% shows the highest tensile strength.

A Study on the Mechanical and Forming Performance of Oil Palm Fiber Reinforced Polypropylene Composite

Polymer Electrolyte Membrane Fuel Cells (PEMFC) can be an efficient energy generator as it offers attractive potentials for certain mobile and portable applications. In PEMFC, the bipolar plate is one of the most important components, and it is multi-functional. This study proposes the use of Graphite (G) and Carbon Black (CB) as hybrid conductive fillers, and Epoxy as the material binder in the bipolar plate. G is used as the main filler, while CB as the second filler materials. The hybrid fillers and the binder were shaped through compression moulding. The effects of different CB contents on the properties of the composite were also observed. The results showed that the decreasing of electrical conductivity was correlated with the increasing of CB content. The different CB contents also resulted in some improvements in other properties such as shore hardness and sample bulk density. The findings promise an enhanced performance of the bipolar plate to be used in PEMFC which is beneficial for mobile and portable application industry. A further study on agglomeration and the mechanical properties such as the flexure strength should be pursued.

The hybrid conductive filler in the bipolar plate for polymer electrolyte membrane fuel cells

This paper discusses the acoustic performance of absorbers constructed using hollow tube structures. Tubes made of polypropylene plastic utilising waste from lollipop sticks were used in this study. The absorption coefficient was tested using the impedance tube method for three different structure arrangements, namely parallel (axial) or perpendicular (transverse and crossed transverse) directions subject to sound incidents on the length of the tubes. The effect of the length or layer thickness of the structures, air gap behind the sample and also introduction of fabric were investigated. The results revealed that the tubes in transverse and crossed transverse arrangements showed greater absorption coefficients compared to the axial arrangement. For a layer thickness of 2 cm and 3 cm, the absorption coefficients were almost unity and the average absorption coefficients were 0.6 above peak frequency. The presence of air gaps shifts the absorption peak to a lower frequency. Enhancements on absorption coefficients in axial arrangements were obtained by introducing fabric covering the front and/or back of the sample.

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Analysis of sound absorption of hollow tube absorbers

The use of Carbon Nanotubes (CNTs) as a reinforcement in conductive polymer composite (CPCs) of bipolar plates nowadays attracts a great deal of attention. Therefore, the aim of this study was to identify the most effective and suitable ratio of CNTs loading in multi filler Graphite (G), Carbon Black (CB) composite using a medium crystallinity and low crystallinity Polypropylene (PP) denoted as MC-PP and LC-PP respectively. The composite were developed through compression molding technique with dry mixing method by using a ball mill to investigate the influence of crystallinity on the dispersion of CNTs in PP matrix. Incorporating CNTs as a third filler in G/CB/CNTs/PP nanocomposites produces a synergistic effect that enhances the electrical conductivity, flexural strength, bulk density and hardness of the nanocomposite which exceeded U.S. DOE requirement. The results indicated that CNTs was given more affect in MC-PP than LC-PP due to better electrical conductivity and mechanical properties of G/CB/CNTs/PP composite as bipolar plate.

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Effect of cnts on the electrical and mechanical properties of polymeric composite as pem fuel cell bipolar plate

This present paper is aims to study the influence of cold rolling process on the microstructure and corrosion behaviors of 316L stainless steel using potentiodynamics polarization testing techniques. The steel with initial thickness of 2.0 mm was unidirectional cold rolled to 10%, 30% and 50% reduction in thickness. The corrosion behaviors of the cold rolled steels were evaluated in phosphate buffered saline (PBS) as their simulated body fluids environment. The pH and temperature of the solution was maintained at 7.31 and 37°C and took approximately 5 hours for each individual test. The microstructure observations of the steels were studied using optical microscope and scanning electron microscopy (SEM). The results showed that the cold rolling process has modified the microstructure of 316L stainless steel by producing extensive surface defects. The microstructure modifications of the cold-rolled steel caused to enhance the corrosion resistance by lowering its corrosion rate to 23% and reduce the pitting resistance by lowering its breakdown potential to 61%. The pit corrosion was extensively appeared after reaching the breakdown potential.

Mohd Zulkefli Selamat

Papers

A Study on the Mechanical and Forming Performance of Oil Palm Fiber Reinforced Polypropylene Composite

The hybrid conductive filler in the bipolar plate for polymer electrolyte membrane fuel cells

Analysis of sound absorption of hollow tube absorbers

Effect of cnts on the electrical and mechanical properties of polymeric composite as pem fuel cell bipolar plate

Effect of Cold Rolling Process on the Microstructure and Corrosion Behaviors of 316L Stainless Steel in Simulated Body Fluids