The effect of carbon fiber plasma treatment on the wettability and interlaminar shear strength of geopolymer composite

Abstract

Interlaminar shear strength (ILSS) of composite depends on the adhesion between its reinforcement and matrix. To improve the mechanical properties of geopolymer composite reinforced with carbon fibers (CFs), the surface of the fibers was modified by plasma treatment in four types of argon atmosphere. The modification of the CFs was evaluated by contact angle measurement, scanning electron microscopy, and X-ray photoelectron spectroscopy. Geopolymer matrix was prepared by the dissolution of metakaolin and an amorphous silica in an aqueous solution of potassium silicate. Vacuum bagging technique was used to prepare the CF/geopolymer composite. The mechanical properties of the composites were determined by ILSS test. The results were compared to results obtained for untreated carbon fibers and their composites. A significant increase of the wettability of CFs was achieved for all plasma treatments and the increase of oxygen functional groups was detected on the CF surface. The results of the mechanical test confirmed improved adhesion for composite samples with CFs treated by plasma in argon atmosphere. Other samples exhibited low or no adhesion between the fibers and matrix. This leads to the conclusion that there are more effects influencing the adhesion than only the properties of CFs.