Plasticization of cellulose triacetate by grafting polybutylacrylate

Abstract

EARLIER publications on the plasticization of cellulose and its esters by grafting polymethylacrylate (PMA), polybutylacrylate (PBA) and polymethylmethacrylate, are [1-5]. I t was found that, in graft copolymerization conducted under conditions where the original polymer showed considerable swelling, if a flexible chain high molecular weight compound compatible with it were grafted (the system cellulose nitrate-PMA), the molecular-chemical mechanism of plasticization obtained [1]. Due to the affinity between the graft copolymer and the original monomer, when cellulose is plasticized by graft copolymerization with PMA or PBA, the possibility of the monomer diffusing inside the supramolecular structures o f the cellulose is retained, and plasticization occurs on the molecular level [3]. When cellulose triacetates (TAC) are plasticized by grafting PMA, which has limited compatibility with them, the process also takes place on the molecular level, but for mechanical mixes, the structural-molecular mechanism of plasticization obtains [4]. We decided it would be very interesting to study the plasticization of a rigid chain polymer by graft copolymefization with an incompatible flexible chain polymer. For the studies we used the plasticization of cellulose triacetate by grafting PBA. Synthesis of graft copolymers. Synthesis of graft copolymers of cellulose triacetates with PBA was by acetylation of already synthesized graft copolymers of celullose. The starting cellulose material was cotton fluff (polymerization coefficient 1000). The graft copolymers were synthesized in an aqueous emulsion of the monomer using the salt Ce+4 as described in [6]. The acetylation was performed in a homogeneous medium (catalyst HCtO,). I t is important to note that the acetylation of graft copolymers is much more rapid than that of the original cellulose material, due, apparently, to the looser packing of the cellulose contained in the graft copolymer. The result of esterification was a solution of the graft copolymer in the acetylating mixture.