Thermo-mechanical properties of pretreated coir fiber and fibrous chips reinforced multilayered composites

Abstract

Coir is one of the most important natural fibers having significant potentiality in structural biocomposites production. The long coir fiber (LCF) and short fibrous chips (CFC) were extracted from the husk of coconut. The dimensions of the CFC were within 1.0–12.5 mm and the LCF were within 2.0 mm. All the fibers and fibrous chips were treated with 5% NaOH (alkali) before the biocomposite manufacturing. Different percentages (8%, 10%, and 12%) of melamine-urea-formaldehyde (MUF) were used to produce the tri-layered medium density composite panels with 12 mm thickness. The mechanical properties (tensile, flexural, and internal bonding strengths) of coir reinforced multilayered composites has been studied for all the produced biocomposites. The morphological, micro-structural, and bonding mechanisms were investigated by Scanning electron microscope and Fourier-transform infrared spectroscopy analysis. Thermal properties of the biocomposites were studied by thermal conductivity, thermogravimetric analysis, and derivative thermogravimetry characterization. The moisture contents of the final composite panels were also investigated in this study. The main objective of this work is to investigate the influences of MUF on treated coir fiber and fibrous chips reinforced tri-layered biocomposites. Beside, a novel sustainable product is developed through reinforcing the fibrous chip with coir fiber in terms of multilayered biocomposite panels.

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

“…The defibrated coir fibers were sieved with a sieve analyzer (ANALYSETTE 3Pro, Germany) to produce uniform fibers before biocomposite panel fabrication. Our previous studies provide detailed descriptions of similar sieving protocols for different natural fibers [24,42]. For this test, 100 g coir fibers were randomly selected from the defibrated materials.…”

“…However, research on coir chips, a byproduct generated during coir fiber processing, is not extensive, particularly not on chips with improved mechanical properties. In our previous study, we reported on the development of coir chips (without extracting into fiber) along with long coir materials reinforced with MUF (melamine-urea-formaldehyde) [24]. However, the internal bonding strengths were less than 0.5 MPa, which, depending on density, is the standard for fiber composite panels.…”

Rice straw and energy reed fibers reinforced phenol formaldehyde resin polymeric biocomposites

“…It is noticed that thermal conductivity also showing an increasing trends like as mechanical properties with the increased loading of energy reeds in composites system. In our previous study (Hasan et al 2021b) for coir fiber and fibrous chips reinforced with MUF polymeric composite panels (medium density), we have found the thermal conductivity values between 0.09302 ± 00.999 and 0.1078 ± 00.0072 W/(m.K). In another study by Ramanaiah et al (2011) for Typha angustifolia reinforced polyester composites (high density) showed the thermal conductivity between 0.137 and 0.432 W/(mK).…”

“…After that, both the rice straw and energy reeds were pretreated with 5% (w/v) of NaOH for removing any impurities present in the raw plant materials. The excessive usage of alkaline reagents could damage the cells of cellulosic substrates (Hasan et al 2021c;Rokbi et al 2011), hence an optimum values of NaOH was used for this pretreatment (Mishra 2003). The materials were soaked in cold water for 24 h at basic pH medium (around 12.0).…”

“…Thermal conductivity of rice straw and energy reed fiber reinforced PF composites were investigated as per MSZ EN ISO 10456 2012 standard through following hot plate method at ambient atmospheric conditions (relative humidity 65 ± 5% and temperature 20 ± 2°C). The detailed procedures for the test is explained in our previous study (coir fiber reinforced MUF composites) (Hasan et al 2021c). The mechanical performances of biocomposite panels were tested in terms of flexural properties (strength and modulus) and IBS through Instron testing machine (4208, United States).…”