Interface Adhesion Properties of Syndiotactic Polypropylene/Cellulose Group Composite: Relationship Between Chemical Structure of Coupling Agent and Reactivity for Cellulose Group

Reinforcement of interfacial adhesion between syndiotactic polypropylene (SPP) and fibrous pure cellulose (FC) was performed by the FC silanizations with 3-aminopropyltrimethoxysilane (APTMS), with hexyltrimethoxysilane (HTMS) and by an addition of a SPP grafted with dimethyl itaconate (SPP-g-DMI: number-average molecular weight = 3.3 x 10(4), DMI cont. = 0.11 wt %), respectively. The adhesion and the morphology were improved by them, respectively. However, their behavior was considerably different. The hexyl group in the HTMS converted the FC surface into hydrophobicity, leading to the hindrance of the interhydrogen bonding in the FC. The silanized FC was embrittled with the increase of the degree of the silanization. In the case of the APTMS, the inter hydrogen bonding was kept because of the existence of the amino group. Whereas, the SPP-g-DMI was unable to penetrate into the cellulose because of its higher molecules, and the interhydrogen bonding was not hindered. The keeping the inter hydrogen bonding was important for the reinforcement of the tensile properties such as Young's modulus and tensile strength in the composite. Furthermore, the interfacial adhesion between the SPP and holocellulose (HC) was studied as well as the SPP/FC. Although the tensile properties were slightly improved by the APTMS silanization and by the addition of the SPP-g-DMI, respectively, the reactivity of the HC was much less than that of the FC. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2798-2806, 2011