Sandwich composites from recycled plastic reinforced with krajood (Lepironia articulata) fiber for building applications

This research aimed to showcase an economical and environmentally friendly approach to producing sandwich-structured composites from recycled plastics and krajood waste. The effects of the contents and particle sizes on mechanical and physical properties, including thermal conductivity and sound absorption coefficient, were investigated. The experimental results were analyzed using Analysis of Variance (ANOVA). The results confirmed that the isocyanate glue at 25% (by weight) and krajood fiber at 75% (by weight) at 40 mesh enhanced the flexural, compressive, and screw withdrawal properties the most. The increase in krajood fiber contents ranged from 75 to 85% (by weight) and increased the water absorption percentages. Core layer samples with high conductivity at 0.085 W/mK are considered suitable for building insulation applications, whereas sandwich composites at 0.189 W/mK are used for outdoor materials. In addition, the sound absorption coefficient and noise reduction coefficient were used to evaluate the application efficiency of sandwich-structured composite materials. The highest sound absorption coefficient and noise reduction coefficient were found using a sound frequency of 1000 Hz. The highest noise reduction coefficient value of 0.78 was found in the core layer sample, meaning that the sample absorbs 78% of sound and reflects the remaining 22% of sound waves back into a room. Thus, the outcomes of this study offer recommendations for the manufacture of sandwich composite materials from recycled polypropylene reinforced with krajood fiber in applications for construction and building products.