Novel insulation panels development from multilayered coir short and long fiber reinforced phenol formaldehyde polymeric biocomposites

Natural sub-bituminous coal as filler enhances mechanical, insulation and flame retardant properties of coir-polypropylene bio-composites

Additives provide substantial improvement in the properties of composites. Although bio-based composites are preferred over synthetic polymer and metal-based composites, they do not have the requisite properties to meet specific needs. Hence, organic, inorganic and metallic additives are included to improve the properties of bio-based composites. Coal is a readily available resource with high thermal insulation, flame resistance and other properties. This work demonstrates the addition of 20-30% natural sub-bituminous coal as filler for coir-reinforced polypropylene (PP) composites and exhibits an increased tensile strength by 66% and flexural strength by 55% compared to the composites without any filler. Such composites are intended for insulation applications and as a replacement for gypsum-based false ceiling tiles. Various ratios of coal samples were included in the composites and their effect on mechanical, acoustic, thermal insulation, flame and water resistance have been determined. A substantial improvement in both flexural and tensile properties has been observed due to the addition of coal. However, a marginal improvement has been observed in both thermal conductivity (0.65 W/mK) and flame resistance values due to the presence of coal. Adding coal increases the intensity of noise absorption, particularly at a higher frequency, whereas water sorption of the composites tends to decrease with an increase in the coal content. The addition of coal improves and adds unique properties to composites, allowing coir-coal-PP composites to outperform commercially available gypsum-based insulation panels.

Effect of Coir Fiber Surface Treatment on Interfacial Properties of Reinforced Epoxy Resin Composites

Coir-fiber-reinforced epoxy resin composites are an environmentally friendly material, and the use of coir fibers improves the mechanical properties of epoxy resin. In order to improve the interfacial adhesion between coir fibers and the epoxy resin matrix, microwave treatment, alkali treatment, acetic anhydride modification, 3-aminopropyltriethoxysilane modification and their reasonable combination method treatments were carried out on coir fibers, respectively. Scanning electron microscopy (SEM), Fourier transform-infrared (FTIR) and X-ray diffraction (XRD) were used to analyze the effects of the different treatments on the characteristics of the coir fibers, and single-fiber pullout tests were performed on the pullout specimens made from the above coir fibers. The results calculated by the proposed estimation method show that the combination method of alkali treatment and 3-aminopropyltriethoxysilane surface modification could better enhance the interfacial bonding ability between coir fibers and epoxy resin with an interfacial shear strength and pullout energy of 6.728 MPa and 40.237 N·mm, respectively. The principal analysis shows that the method can form both mechanical interlocking and chemical bonds at the interface to enhance the interfacial bonding ability. This study provides a more suitable method for improving the interfacial properties of coir-fiber-reinforced epoxy resin composites and has implications for the study of natural fiber composites.

Fabrication and Characterization of Degradable Crop-Straw-Fiber Composite Film Using In Situ Polymerization with Melamine-Urea-Formaldehyde Prepolymer for Agricultural Film Mulching

Soil mulch composite films composed of biodegradable materials are being increasingly used in agriculture. In this study, mulch films based on wheat straw fiber and an environmentally friendly modifier were prepared via in situ polymerization and tested as the ridge mulch for crops. The mechanical properties of the straw fiber film were significantly enhanced by the modification. In particular, the films exhibited a noticeable increase in dry and wet tensile strength from 2.35 to 4.15 and 0.41 to 1.51 kN/m, respectively, with increasing filler content from 0% to 25%. The contact angle of the straw also showed an improvement based on its hydrophilicity. The crystallinity of the modified film was higher than that of the unmodified film and increased with modifier content. The changes in chemical interaction of the straw fiber film were determined by Fourier transform infrared spectroscopy, and the thermal stability of the unmodified film was improved by in situ polymerization. Scanning electron microscopy images indicated that the modifier was uniformly dispersed in the fiber film, resulting in an improvement in its mechanical properties. The modified straw fiber films could be degraded after mulching for approximately 50 days. Overall, the superior properties of the modified straw fiber film lend it great potential for agricultural application.

The Influence of High-Intensity Ultrasonication on Properties of Cellulose Produced from the Hop Stems, the Byproduct of the Hop Cones Production

The goal of this work is to evaluate the hop stems, a byproduct of hop cones production, as a potential source of cellulose. Hop stems contain up to 29% of cellulose. The cellulose isolation was conducted through the thermochemical treatment. After high-speed blending, the cellulose was characterized by 67% of crystallinity degree obtained from X-ray diffraction and median diameter of 6.7 nm obtained from atomic force microscopy imaging. The high-intensity ultrasonication (HIUS) was applied to reach further disintegration of cellulose fibers. The longer HIUS treatment resulted in decrease in crystallinity degree even up to 60% and decrease in the fiber diameter up to 4 nm. The Fourier transform infrared spectroscopy (FTIR) spectra showed that HIUS treatment led to changes in intermolecular hydrogen bonds. The stability of cellulose dispersions versus length of HIUS treatment was monitored over 14 days with back dynamic light scattering and laser Doppler electrophoresis methods. Obtained results are evidence that the hop stems are a potential source of cellulose and that it is possible to obtain stable dispersions after HIUS treatment. This was the first time that the properties of hop cellulose have been described so extensively and in detail after the use of HIUS treatment.

Product Development of Natural Fibre-Composites for Various Applications: Design for Sustainability

New product development review article aims to consolidate the principles and current literature on design for sustainability to seek the field’s future direction. In this point of view, the design for sustainability methods can be established under the idea of sustainability in dimensions of ecology, economy and social pillars. Design for sustainability concept is implemented in concurrent engineering, including concept, embodiment and detail design processes. Integrating sustainability in engineering designs is crucial to producing greener products, system innovation, and services aligned with current market demand. Currently, many concurrent engineering studies related to natural fibre-reinforced polymer composites associated with sustainability enhance the application of design for sustainability techniques by professional designers. However, the current literature is scarce in bridging the design for sustainability concept with concurrent engineering during the design development stage, and these areas should be further developed. Several other future research directions, such as the need for aligning with principles and applications, along with exploring the relationships between the design for sustainability techniques and views of sustainability, are presented in this review paper.

Rapid Measurement of Cellulose, Hemicellulose, and Lignin Content in Sargassum horneri by Near-Infrared Spectroscopy and Characteristic Variables Selection Methods

Near-infrared (NIR) spectroscopy and characteristic variables selection methods were used to develop a quick method for the determination of cellulose, hemicellulose, and lignin contents in Sargassum horneri. Calibration models for cellulose, hemicellulose, and lignin in Sargassum horneri were established using partial least square regression methods with full variables (full-PLSR). The PLSR calibration models were established by four characteristic variables selection methods, including interval partial least square (iPLS), competitive adaptive reweighted sampling (CARS), correlation coefficient (CC), and genetic algorithm (GA). The results showed that the performance of the four calibration models, namely iPLS-PLSR, CARS-PLSR, CC-PLSR, and GA-PLSR, was better than the full-PLSR calibration model. The iPLS method was best in the performance of the models. For iPLS-PLSR, the determination coefficient (R2), root mean square error (RMSE), and residual predictive deviation (RPD) of the prediction set were as follows: 0.8955, 0.8232%, and 3.0934 for cellulose, 0.8669, 0.4697%, and 2.7406 for hemicellulose, and 0.7307, 0.7533%, and 1.9272 for lignin, respectively. These findings indicate that the NIR calibration models can be used to predict cellulose, hemicellulose, and lignin contents in Sargassum horneri quickly and accurately.