Investigations on fiber–matrix properties of heat-treated and UV-treated regenerated cellulose fibers

The mechanical properties of a fiber-reinforced compound depend on many factors. Fiber orientation, fiber length, fiber type and the bonding of the fiber to the polymer is also of high significance. The adhesion work between the fiber and the polymer is based on the surface free energy of the components. The surface free energy of two different polymers and fibers was determined, and their interfacial shear strength was determined in single fiber extracts. Fiber-matrix adhesion treatment at temperatures of 240 °C and high-energy light can influence the chemical structure of the surface of fibers, which is reflected in changed surface energy. It was shown that the adhesion of regenerated cellulose fibers (RCF) and polypropylene (PP) can be increased with a coupling agent, and fiber treatment by UV-light further enhances this effect. Both thermal and UV treatment lead to degradation of the RCF structure and reduce the reinforcing effect.