Effects of reprocessing on the hygroscopic behavior of natural fiber high‐density polyethylene composites

Abstract

Detailed analysis of the effects of recycling process on long-term water absorption, thickness swelling, and water desorption behavior of natural fiber highdensity polyethylene composites is reported. Composite materials containing polyethylene and wood flour, rice hulls, or bagasse fibers and 2% compatibilizer were produced at constant fiber loading and were exposed to a simulated recycling process consisting of up to five times grinding and reprocessing under controlled conditions. A wide range of analytical methods including water absorption/desorption tests, thickness swelling tests, density measurement, scanning electron microscopy, image analysis, contact angle, fiber length analysis, Fourier transform infrared spectroscopy, and tensile tests were employed to understand the hygroscopic behavior of the recycled composites. Water absorption and thickness swelling behaviors were modeled using existing predictive models and a mathematical model was developed for water desorption at constant temperature. Results indicated that generally the recycled composites had considerably lower water absorption and thickness swellings as compared with the original composites which were attributed to changes in physical and chemical properties of the composites induced by the recycling process. Water desorption was found to be faster after recycling.

Mechanical, water absorption, and morphology of recycled polymer blend rice husk flour biocomposites

“…However, the waste plastics offer a promising source of raw material for the composites because of the huge amount generated every day and the lower cost than virgin plastics . Traditionally, the polymer matrix used in NFPCs is only made from a single type of plastic . However, the studies of NFPCs based on polymer blends (PB) are very limited .…”

“…Moisture absorption of natural fibers is becoming a critical concern, especially for their potential outdoor use in building application . Water absorption (WA) is an important property that determines the durability and performance of NFPCs .…”

“…Moisture absorption of natural fibers is becoming a critical concern, especially for their potential outdoor use in building application . Water absorption (WA) is an important property that determines the durability and performance of NFPCs . As discussed by Tajvidi et al, WA in NFPCs is dependent upon the formulation of resultant composites and processing features such as processing temperature, rotating screw speed, etc., but not limited to the types of natural fiber or plastic, processing system, size, and dispersion of fiber as well as quality of interfacial.…”

“…Water absorption (WA) is an important property that determines the durability and performance of NFPCs . As discussed by Tajvidi et al, WA in NFPCs is dependent upon the formulation of resultant composites and processing features such as processing temperature, rotating screw speed, etc., but not limited to the types of natural fiber or plastic, processing system, size, and dispersion of fiber as well as quality of interfacial. In order to improve the water resistance of NFPCs, coupling agents such as maleic anhydride polypropylene (MAPP) and maleic anhydride polyethylene (MAPE), compatibilizers, or other surface treatment of fibers such as silane .…”

Preparação e caracterização de biocompósitos baseados em fibra de curauá, biopolietileno de alta densidade (BPEAD) e polibutadieno líquido hidroxilado (PBHL)

“…Os ensaios de absorção de água permitem avaliar propriedades como a estabilidade dimensional dos materiais, assim como os resultados podem ser tomados como indicadores da adesão na interface fibra/matriz [48] . A Figura 8 mostra o perfil de absorção de água dos compósitos de BPEAD/PBHL reforçados com fibra de curauá.…”