Properties of cellulose reinforced composites: A review

This paper provides a review of cellulose, sources, extraction, molecular structure, cellulose whiskers, preparations, and morphology. The mechanical and thermal properties of cellulose reinforced composites are also discussed. Detail structure of Nano whiskers is also reported. As a renewable biomaterial, the most common source of cellulose is the plant. These plants include fruit fibers (coir), seed fibers (cotton), wood, leaf fibers (sisal), bast fibers (jute, kenaf, and hemp). Other sources of cellulose are from micro-organisms such as fungi, tunicates, bacteria, and algae. Cellulose whiskers are isolated from cellulose fibers by acid hydrolysis. Cellulose micro fibril structures are made of both amorphous and crystalline regions. The amorphous regions are vulnerable to hydrolysis by acids compared to the crystalline domains. Several techniques among which are Field Emission Scanning Electron Microscopy (FESEM), Transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM) have been used to study the morphology of cellulose whiskers. An interface between cellulose whisker and matrix is a transition zone between the matrix and the cellulose whiskers. It plays an important role in the overall mechanical properties of the composites. A soft interface domain will yield a greater resistance to fracture, while the composite will be low in stiffness and strength. On the other hand, a stiffer interface domain may cause the composite to be strong and stiff and less resistant to fracture. The addition of CW into polymers matrices has little or no effect on the glass transition temperature, (Tg) except on the modification of CW. Keywords: Cellulose, whiskers, mechanical, thermal, properties, biomaterials

Preparation and Properties of Nano Coir Cellulose Whiskers Enhanced CS/PVA Composite Film

Nano coir cellulose whiskersare materials abstracted from mesocarp of coconut shell which was modified by using KH570 as a coupling agent and modified nano coir cellulose whiskers need to be dispersed in chitosan/polyvinyl alcohol (CS/PVA) mixture solution. Because of regular structure and high crystallinity, nano coir cellulose whiskers could be applied in medical materials.In this paper, the results obtained with solution casting method by characterizing and analyzing structure, thermal properties, crystallization behavior and morphology of nano coir cellulose whiskers enhanced CS/PVA composite filmby FTIR, DSC, TG, XRD and SEM test. Different content of modified nano coir whiskers and CS/PVA composite film were preparedand themechanical properties of the composite film were also conducted. The results show that the tensile strength and Young's modulus of the CS/PVA composite film with modified nano coir whiskers are significantly improved, and Elongation break increases at first and then decreases, which indicates nano coir cellulose whiskers are good materials for medical purpose.