Effect of Matrix Polymer Properties on the Interfacial Adhesion Between Cellulose Fiber and Polypropylene

Abstract

The effect of matrix properties on the fiber to polymer adhesion in a model cellulose fiber reinforced composite system was studied.Pure polypropylene (PP) of different mechanical properties (tensile and shear modulus) were used to form adhesion samples with a regenerated cellulose fiber (TencelR) and tested using the microbond adhesion test.The adhesion between the cellulose fiber and pure PP were related to the shear-lag stress transfer model proposed by Cox.It was found that if chemical bonding is not present at the fiber-matrix interface, interfacial adhesion can be directly related to the product of matrix strain and the square root of the matrix shear modulus.Since polypropylene is a semi-crystalline polymer, however, care must be taken to include the effect of matrix crystallinity.When maleic anhydride grafted polypropylene (maPP) was introduced at the fiber-matrix interface, the interfacial adhesion was significantly higher than for the comparable cellulose fiber and purepolypropylene system.The increase in the interfacial adhesion is attributed to the formation of covalent bonds between the cellulose fiber and the maPP matrix.