Mechanical, Morphological, Thermal and Dynamic Study of Composites of Unsaturated Polyesters-Date Palm Leaf Fiber DPLF

In order to improve the properties of unsaturated polyesters, this study discusses the possibilities of developing a natural waste, date palm leaf fiber DPLF, produced in the northern Algerian Sahara, associated with the polymer matrix of a thermosetting polyester resin UP. For this purpose, composite plates containing virgin fiber at rates of 6 and 10% were treated with an alkaline solution of 6% NaOH on the one hand, and a silane compound on the other. In this research, a mechanical study of strength and elongation at break was carried out. In addition, morphological behavior was followed by SEM scanning electron microscopy. ATG thermogravimetric analysis and energy flow were monitored by DSC differential scanning calorimetry. Also, a study of the water absorption capacity has been conducted. In addition, a dynamic mechanical analysis DMA was carried out. The findings of this study show that there is a favorable mechanical behavior for the composites containing the 6% and 10% DPLF fiber, with alkaline NaOH and Silane treatment. They also show that the chemical treatment with alkaline solution and silane gives composites certain thermal stability compared to those with untreated fiber. Findings also explore that the absorption of water by the various composites shows that the chemical treatment promotes some intermolecular associations with water. Findings also show that the storage modulus (E') increases when the composite contains 10% DPLF, treated and untreated, and the maximum value of the tangent moves towards the high temperature for the treated and untreated fiber composite.

AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF NATURAL FIBER TREATMENT AND MARINE ENVIRONMENT ON CANNABIS SATIVA/EPOXY LAMINATES

Materials have helped in evolving technology to a great extent. Composites have replaced conventional metals/non-metals because of their lightweight. Natural Fibres have been need of the hour owing to environmental concerns and ease of availability. In this work, Cannabis Sativa fibers were treated with 5% Potassium Hydroxide solution. The laminates were prepared by the Compression Moulding technique by reinforcing treated and untreated fibers with an epoxy matrix material. To access the durability of natural fiber composites in the marine environment, prepared laminates were aged in seawater for 150 days. Tensile, flexural and moisture absorption behavior tests have been performed to estimate the durability in seawater. The data obtained have been compared with pristine treated and untreated fiber reinforced samples. From the results, it has been observed that tensile and flexural behavior of untreated fiber reinforced composites were superior to a treated counterpart in both pristine and aged conditions.

Studies on physico-mechanical behaviour of kenaf/glass fiber reinforced epoxy hybrid composites

In this study, various treated, untreated, and treated kenaf/glass fiber composites were fabricated using epoxy resin. A portion of kenaf fibers were subjected to treatment with alkali, sub-portion was taken for benzoyl peroxide and potassium permanganate prior to composite fabrication. This treatment on the composite material was undertaken to achieve improved modification of the interface between the matrix and fiber bond. A portion of the glass fiber was used for enhancing the mechanical properties of the hybrid composite. The tensile strength, flexural, density, water absorption and chemical resistance of the composites were analyzed using standard methods. FTIR was conducted on the fiber to ascertain the chemical treatment on the fibers, FESEM was used for the morphological study. The results obtained showed that the tensile and flexural strength improved from 46.45-298.3 kgf, and 10.5-54.7 kgf, respectively, in the composite samples. Chemical resistance of the kenaf fiber treated potassium permanganate composite improved compared to the untreated fiber composite in both cases. The density and water absorption properties of the composites were found to decrease in the treated fibers compared to untreated fiber composites, this treated composites showed less water absorption and density. The FTIR result revealed that reaction has taken place between the fiber and the treatment reagent. Hence, fiber modification has improved the properties of the composites due to increase in fiber-matrix interaction. KEY WORDS: Chemical properties, Epoxy resin, Hybrid, Kenaf, Mechanical strength, Natural fiber Bull. Chem. Soc. Ethiop. 2021, 35(1), 171-184. DOI: https://dx.doi.org/10.4314/bcse.v35i1.15

Ethanol Production from Corn Fiber Separated after Liquefaction in the Dry Grind Process

Conversion of corn fiber to ethanol in the dry grind process can increase ethanol yields, improve coproduct quality and contribute to process sustainability. This work investigates the use of two physio-chemical pretreatments on corn fiber and effect of cellulase enzyme dosage to improve ethanol yields. Fiber separated after liquefaction of corn was pretreated using (I) hot water pretreatment (160 °C for 5, 10 or 20 min) and (II) wet disk milling and converted to ethanol. The conversion efficiencies of hot water pretreated fiber were higher than untreated fiber, with highest increase in conversion (10.4%) achieved for 5 min residence time at 160 °C. Disk milling was not effective in increasing conversion compared to other treatments. Hydrolysis and fermentation of untreated fiber with excess cellulase enzymes resulted in 33.3% higher conversion compared to untreated fiber.

Thermal degradation of coir fiber reinforced low-density polyethylene composites

In the present study, the effect of fiber surface treatments (alkali and acrylic acid) on the thermal degradation behavior of coir fiber (CF)-low-density polyethylene (LDPE) composites with or without compatibilizer (maleic anhydride grafted LDPE, MA-g-LDPE) using thermogravimetric and derivative thermogravimetric analyses (TG/DTG) was analyzed and compared with those of untreated fiber composites. The TG/DTG results revealed that the thermal stability of the CF improved after the chemical treatments. However, the composite containing treated fiber showed lower thermal stability and started to degrade at a faster rate above 380°C in comparison to composites containing untreated fiber composites. Furthermore, the addition of MA-g-LDPE led to improvement in the thermal stability of both treated and untreated fiber composites in comparison to the same composite formulation without MA-g-LDPE. The composite containing untreated fiber and MA-g-LDPE demonstrated superior thermal stability among all the formulated composites, indicating strong fiber-matrix adhesion.

Effect of alkali treatment on the flexural properties of a Luffa cylindrica-reinforced epoxy composite

This experimental study was conducted to investigate the effect of NaOH concentration and treatment time on the flexural properties ofLuffa cylindricafiber-reinforced epoxy composites. Significant improvement (up to 84.92%) in the flexural properties for the treated fiber composite compared with the untreated fiber composite was observed. Both treated and untreated fiber composites were then subjected to different environmental treatments (saline water, distilled water, and subzero temperature). To find out the changes in flexural strength immediately after treatment, the same test was carried out on the composites. Degradation in the flexural strength of both treated and untreated fiber composites, when subjected to environmental treatments, was observed. They were found within the range of 2%–20% and were found to be least in subzero treatment. The SEM micrograph indicates that alkali treatment is effective in improving the adhesion between the fiber and matrix.

Exploration of Local cellulosic-fiber; its Modification and Potential use by the Industry

ABSTRACTDemand for newer, stronger, stiffer, yet lighter-weight and environmental friendly (biodegradable) materials in the fields such as automobile for non-structural applications are ever increasing. The principal reasons for using natural (cellulosic) fibers is they possess several attractive properties such their economic feasibility, enhanced sustainability, good specific mechanical properties, and desirable aspect ratio for good performance after melt-processing. Natural fiber composite materials are now being rapidly utilized in automobile industries, and they have become the forefront of research and development activity. An interesting alternative for reinforcing soft polymeric matrices with short fibers is the use of cellulose fibers which show remarkable reinforcing effects in thermoplastics such as polypropylene. The current study made an attempt to investigate the suitability of sisal fibers for automobile industry for non-structural and low-strength interior applications. In this work native sisal fibers were extracted and the effect of alkali treatment on their morphological, tensile, moisture absorption and thermal properties were studied. Scanning electron micrographs indicated roughening of the surface of the fiber strands due to the removal of the hemicellulose layer on alkali treatment. The maximum weight-gain for the composite prepared from treated fibers was 2.12 %, while that for the composite prepared from untreated fiber was 4.33 %. From the thermograms, the results indicate initial degradation for the treated fiber to have improved from 174 °C to 230 °C (56 °C shift) when compared to the untreated fiber. This fiber has competitive advantages when evaluated with other natural fibers. A polymer composite was processed from the chemically modified fiber, profiled against equivalent material systems in Ashby material property charts exhibited its suitability for light, low strength and low flexure material applications which can use a potential replacement of fibres being used currently.

Effects of Alkali Treatment and Fiber Content on the Properties of Bagasse Fiber-Reinforced Epoxy Composites

In this research work, natural fiber reinforced composites of bagasse fiber-epoxy resin were prepared. The chemical treatments using sodium hydroxide (NaOH) at 1,3,5,7 wt% were carried out to modify the fiber properties. Thermogravimetric analysis (TGA) was used to study the thermal stability of treated and untreated fibers. The effects of fiber treatment and fiber contents on mechanical properties of bagasse-epoxy composite were investigated. The characteristics of bagasse-epoxy resin composites exposed to high temperature as well as water absorption behavior were determined. The results from the TGA revealed that alkalization improved thermal stability of bagasse fiber. Treated bagasse fibers also had lower moisture content as compared to untreated fiber. The experimental results showed that the flexural properties of composites prepared from treated bagasse fibers were enhanced as compared to the untreated fiber composite. Thermal degradation study demonstrated that treated bagasse fiber composites experienced lower weight loss than untreated fiber composites. From water absorption study, it was observed that the treated bagasse fiber composites had lower water absorption values than those of untreated fiber based composites.

Effect of gamma irradiation aging on mechanical and thermal properties of alfa fiber–reinforced polypropylene composites

Recently, the interest in plant fiber composites has considerably increased due to the new environmental legislation as well as consumer pressure that forced manufacturing industries to search substitutes to the conventional materials. The aim of this article is to assess the effects of different does of gamma irradiation on the physico-mechanical properties of the composites PP / alfa fiber treated and untreated. The Young’s modulus of composites increases in the presence of alfa fiber and it was more pronounced with untreated ones resulting by the cross-linking, whereas elongation and maximum strain decreased as dose irradiation raised. Fourier transform infrared spectroscopy results showed that the virgin PP has better stability to gamma irradiation than treated and untreated composites. Thermogravimetric analysis showed that the addition of the treated and untreated fiber greatly improves the thermal stability of the polymer matrix before and after gamma irradiation. Composites based on treated and untreated fiber have better storage modulus than virgin matrix.