Khalina Abdan

Effect of Fiber Treatment on Mechanical Properties of Kenaf Fiber-Ecoflex Composites

The composite material based on whole stem kenaf fiber (WSK) and Ecoflex (biodegradable thermoplastic) were prepared by melt blending technique and characterized. The composites were prepared using different fiber loadings and the fiber was treated with various concentrations of NaOH solution by soaking for 3 h. The compounding of composite were carried out at different fiber loadings (10%, 20%, 30%, 40%, 50%) using Brabender internal mixer at 130°C for 10 min. The composites were then pressed using compression molding to produce biodegradable kenaf/Ecoflex sheets. The effects of kenaf fiber loading and NaOH treatment of WSK fiber surface on mechanical properties was examined. The results showed that 40% fiber loading improved the tensile strength properties and WSK fiber treated with 4% NaOH was found to enhance tensile and flexural properties compared with untreated fiber. The FTIR characterization showed that alkali treatment removes hemicellulose and lignin from WSK kenaf fiber surface.

Modeling the Thin‐Layer Drying of Fruits and Vegetables: A Review

The drying of fruits and vegetables is a complex operation that demands much energy and time. In practice, the drying of fruits and vegetables increases product shelf-life and reduces the bulk and weight of the product, thus simplifying transport. Occasionally, drying may lead to a great decrease in the volume of the product, leading to a decrease in storage space requirements. Studies have shown that dependence purely on experimental drying practices, without mathematical considerations of the drying kinetics, can significantly affect the efficiency of dryers, increase the cost of production, and reduce the quality of the dried product. Thus, the use of mathematical models in estimating the drying kinetics, the behavior, and the energy needed in the drying of agricultural and food products becomes indispensable. This paper presents a comprehensive review of modeling thin-layer drying of fruits and vegetables with particular focus on thin-layer theories, models, and applications since the year 2005. The thin-layer drying behavior of fruits and vegetables is also highlighted. The most frequently used of the newly developed mathematical models for thin-layer drying of fruits and vegetables in the last 10 years are shown. Subsequently, the equations and various conditions used in the estimation of the effective moisture diffusivity, shrinkage effects, and minimum energy requirement are displayed. The authors hope that this review will be of use for future research in terms of modeling, analysis, design, and the optimization of the drying process of fruits and vegetables.

A Review on Pineapple Leaves Fibre and Its Composites

Natural fibre based composites are under intensive study due to their ecofriendly nature and peculiar properties. The advantage of natural fibres is their continuous supply, easy and safe handling, and biodegradable nature. Although natural fibres exhibit admirable physical and mechanical properties, it varies with the plant source, species, geography, and so forth. Pineapple leave fibre (PALF) is one of the abundantly available wastes materials of Malaysia and has not been studied yet as it is required. A detailed study of chemical, physical, and mechanical properties will bring out logical and reasonable utilization of PALF for various applications. From the socioeconomic prospective, PALF can be a new source of raw material to the industries and can be potential replacement of the expensive and nonrenewable synthetic fibre. However, few studies on PALF have been done describing the interfacial adhesion between fibres and reinforcement compatibility of fibre but a detailed study on PALF properties is not available. In this review, author covered the basic information of PALF and compared the chemical, physical, and mechanical properties with other natural fibres. Furthermore, it summarizes the recent work reported on physical, mechanical, and thermal properties of PALF reinforced polymer composites with its potential applications.

Mechanical properties and water absorption behavior of hybridized kenaf/pineapple leaf fibre-reinforced high-density polyethylene composite

This work provides variation in mechanical properties such as tensile, flexural and impact strength of hybridized kenaf and pineapple leaf fibre-reinforced high-density polyethylene composite. Two or more natural fibres are hybridized to provide an effective means of designing materials for various service requirements. The composite of kenaf/pineapple leaf fibre high-density polyethylene-based hybrid composite with different weight proportion of fibres were prepared. Total overall fibre loading in the composite was kept at 40%. The hybrid composites prepared were subjected to water immersion for 14 days to see how this concept can affect water uptake. At equal percentage ratio of the fibres, hybridization effect was optimized for tensile and flexural test; however, K6P4 gave the optimum impact strength while K3P7 resulted in the least overall water uptake. Strength and modulus values increased with increase in percentage of pineapple leaf fibre in the composite and the higher aspect ratio of kenaf helped in the dispersion of matrix in the composite. Favorable balance between the inherent advantages and disadvantages of these two fibres complemented each other. While pineapple leaf fibre helped the composite in tensile and flexural properties, kenaf provided impact strength and in reduction of water uptake. Dependence of modulus on the percentage of cellulose in natural fibres was clear. Kenaf and pineapple leaf fibre offered tremendous potential for hybridization. SEM was used to describe this interesting phenomenon.

Poly(Lactic Acid)(PLA)-reinforced kenaf bast fiber composites : the effect of triacetin.

In this article, the mechanical, morphological, and dynamic-mechanical properties of the blends of PLA and kenaf bast short fiber were investigated. The composites, with different fiber loading and triacetin content, were prepared by melt blending techniques using a Brabender internal mixer at 60 rpm and 170°C for 10 min and their properties were examined. Pure PLA was used as a reference for the biocomposite samples. Triacetin was used as a plasticizer for PLA and PLA/kenaf composites in order to study the improvement in tensile properties. The tensile strength and stiffness of unplasticized biocomposite materials decreased with the addition of kenaf bast fibers but improved with the addition of triacetin. The optimum fiber loading was 30 wt% kenaf fibers in the PLA matrix with the addition of 5% triacetin. The dynamic mechanical analyses showed that triacetin improved the thermal stability of the biocomposites. The triacetin increased the storage modulus and gave a lower softening temperature for plasticized biocomposites. The micrographs of the tensile specimens and their fractured surfaces, which were examined by scanning electron microscopy, demonstrated that better adhesion between the fibers and the matrix was achieved with the addition of the plasticizer.

Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres

Natural fibres are very versatile materials, their properties vary with chemical composition and physical structure. The effects of alkali, silane and combined alkali and silane treatments on the mechanical (tensile), morphological, and structural properties of Pine Apple Leave Fibres (PALF) and Kenaf Fibres (KF) were investigated with the aim to improve their compatibility with polymer matrices. The effectiveness of the alkali and saline treatments in the removal of impurities from the fibre surfaces was confirmed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectrometry (FTIR) observation. The morphological study of treated PALF and KF by SEM indicates that silane treated fibres have less impurities and lignin and hemicelluloses removed than those by other chemical treatments. Silane treated PALF and KF display better tensile strength than those of untreated, alkaline and NaOH-silane treated. Droplet test indicates that the Interfacial Stress Strength (IFSS) of alkali and silane treated PALF and KF are enhanced whereas silane treated fibres display highest IFSS. It is assumed that fibre treatments will help to develop high performance KF and PALF reinforced polymer composites for industrial applications.

Effect of chemical surface treatment on the mechanical properties of reinforced plasticized poly(lactic acid) biodegradable composites

Biodegradable composites were prepared by melt-blending technique using 30 wt% kenaf bast fiber (KBF) to reinforce 70 wt% plasticized poly(lactic acid) (PLA). The KBF was treated with various percentages of sodium hydroxide (NaOH), whereas 5% triacetin was used as plasticizer. The effects of the KBF surface treatments on the tensile, flexural, impact strength, and DMA of the biocomposites were investigated. Tensile, flexural, and impact testing results reveal that 4% of NaOH-treated KBF produced composites with optimum tensile strength (62 MPa), flexural strength (67 MPa), and the impact strength (42 kJ/m2). The removal of the lignin from the fiber during the surface treatment caused the increment in the modulus result. This finding is also supported by the dynamic mechanical analysis. The storage modulus of plasticized PLA/treated KBF is higher than the storage modulus of plasticized PLA/untreated KBF which is attributed to the enhancement of the fiber—matrix adhesion. The loss modulus results showed that the Tg of the plasticized composites was shifting to higher temperature, from 55°C for plasticized PLA/untreated KBF to 65°C for plasticized PLA/treated KBF. The increase in Tg shows that the plasticized PLA has low chain mobility when reinforced with treated KBF, indicating better interaction.

Properties of sugarcane bagasse/poly(vinyl chloride) composites after various treatments

The properties of sugarcane filled poly(vinyl chloride) (PVC) composites after various treatments were studied. The studied chemical treatments were fiber treatment with benzoic acid, fiber treatment with sodium hydroxide, and the incorporation of poly[methylene(polyphenyl) isocyanate] (PMPPIC) as coupling agent. Results showed that chemical-treated composites obtain higher tensile strength and modulus as compared to untreated sugar-free bagasse/PVC composite. Among the three chemical treatments, the incorporation of PMPPIC gave the highest tensile strength and modulus. Both tensile strength and modulus of treated composite, however, are lower than those of untreated sugarcane bagasse (SB)-filled composite when unwashed bagasse, which contained sugar, was used. It is suspected that sugar may contribute to the tensile strength and modulus of the composite and hence, the SB can be used as reinforcing agent without further chemical treatment.

Modelling Effective Moisture Diffusivity of Pumpkin (Cucurbita moschata) Slices under Convective Hot Air Drying Condition

Abstract This study seeks to investigate the effects of temperature (50, 60, 70 and 80 °C) and material thickness (3, 5 and 7 mm), on the drying characteristics of pumpkin (Cucurbita moschata). Experimental data were used to estimate the effective moisture diffusivities and activation energy of pumpkin by using solutions of Fick’s second law of diffusion or its simplified form. The calculated value of moisture diffusivity with and without shrinkage effect varied from a minimum of 1.942 × 10–8 m2/s to a maximum of 9.196 × 10–8 m2/s, while that of activation energy varied from 5.02158 to 32.14542 kJ/mol with temperature ranging from 50 to 80 °C and slice thickness of 3 to 7 mm at constant air velocity of 1.16 m/s, respectively. The results indicated that with increasing temperature, and reduction of slice thickness, the drying time was reduced by more than 30 %. The effective moisture diffusivity increased with an increase in drying temperature with or without shrinkage effect. An increase in the activation energy was observed due to an increase in the slice thickness of the pumpkin samples.

Tensile and Impact Properties of Sugarcane Bagasse/Poly(vinyl Chloride) Composites

Sugarcane bagasse is divided into two main components, pith and rind, with “pith” representing the inner part of the sugarcane bagasse and “rind” as the outer part. In this study, the tensile and impact properties of untreated pith/ poly(vinyl chloride) composites were compared to that of untreated rind composites using the same matrix with variation of fibre content. It was observed that the tensile strength and modulus of rind/PVC composites are higher than the unfilled PVC at composite fibre contents of 30% and 40%. Additionally, the rind composites exhibited superior strength and stiffness in comparison with the pith composites.