A study on moisture absorption and swelling in bio-based jute-epoxy composites

Abstract

Woven jute fibers, a class of affordable and biodegradable ‘green’ fibers, are being increasingly used as a substitute for the artificial glass and carbon fibers used in polymer composites. However, all natural fiber composites absorb water and swell in a moist environment For the first time, the swelling and weight gain behavior of bio-based composites made from jute fibers and bio-based or ordinary epoxy is presented in this experimental characterization study. Several such composites specimens were made using a low-pressure resin injection process similar to resin transfer molding; the specimens were made according to ASTM D 570 consisted of three compositions: pure resin, pure resin with a single jute fabric layer, and pure resin with two jute fabric layers. The effects of number of layers on moisture absorption, thickness swelling, volume swelling, and density were measured as a function of immersion time. It is observed that the moisture diffusion rate into composites increases with an increase in the jute-fiber-to-epoxy ratio. The type of epoxy used as the matrix appeared to have an influence on the moisture absorption percentages of the composites – the study showed that both water absorption and swellings were higher in the bio-epoxy parts compared to the epoxy parts. The swelling of composites was correlated with an increase in diameters of jute fiber in water and possibilities for the appearance of micro-cracks around fibers in composites were discussed. The data on moisture absorption, thickness swelling, and volume swelling of bio-based composites made from woven jute fibers, and bio-based and ordinary epoxies presented in this article will lead to a better understanding of how these composites react in wet environmental conditions.

Dynamic Mechanical Behavior Analysis of Flax/Jute Fiber-Reinforced Composites under Salt-Fog Spray Environment

“…Similar to what was observed by Wang and Petru [40], a clear decrease of the dynamic stiffness was found with increasing the composites' moisture content. Due to the polysaccharide content of natural fibers and the voids and cracks in the epoxy matrix bulk, flax and jute fibers tended to absorb a great amount of water when composites were exposed to humid environments such as a marine one [10,23]. Hence, the penetration of water molecules and ions (i.e., Na + and Cl − ) within the composite structure led to softening both matrix and natural reinforcing fibers, as well as chemically and physically degrading the inherently weak fiber/matrix interface.…”

“…This can be partially ascribed to the softening and plasticization phenomena of natural fibers and thermoset matrix [19,20]. In particular, different combined chemo-physical phenomena (i.e., plasticizing, swelling, and hydrolysis) occur in organic resins due to hydrothermal aging [21][22][23]. Furthermore, it is widely known that natural fibers show a high tendency to moisture absorption [24,25] due to the hydrophilic nature of their polysaccharide constituents (i.e., mainly cellulose and hemicellulose).…”

Optimizing the formulation of polypropylene and rubberwood flour composites for moisture resistance by mixture design

“…18 When water molecules infiltrate into the composite, the wood flour tends to swell, resulting in localized yielding of the polymer matrix and loss of adhesion between the wood flour and matrix. 18,36,37 Furthermore, the addition of MAPP about 3 wt% is close to optimal for MOR, based on the regression fit. Because MAPP acts as a compatibilizer providing a hydrophobic-rich layer attached to wood flour.…”

Critical Review of the Parameters Affecting the Effectiveness of Moisture Absorption Treatments Used for Natural Composites

“…The investigations show that the fiber swelling and moisture absorption are higher in the bio-epoxy-based composite relative to the synthetic one. The higher swelling rate noticed for the fully green composite is justified, since the bio-epoxy contains a specific percentage of cellulose [159]. Generally, soy protein resins absorb a higher quantity of water, which mitigates their mechanical aspects.…”