Effect of Preparation Conditions on Crosslinking Behavior of Linseed Oil-Based Thermosetting Polymer

Abstract

Bio-based materials have received more attention to replace materials from petroleum resources because of sustainability reason.  Plant oil is one of the most interesting raw materials to produce thermosetting polymer.  A crosslinking reaction between epoxidized linseed oil and vegetable oil-based crosslinkers is investigated in present study.  Two types of crosslinker including fatty acid dimer and fatty acid trimer were reacted with epoxidized linseed oil.  A rotational rheometer equipped with cone-and-plate geometry was used to monitor the progress of three-dimensional network formation.  A curing phenomenon was illustrated by the increment in storage modulus of the reaction mixture.  The trifunctional crosslinker was more effective than difunctional crosslinker for an uncatalyzed systems at the reaction temperature of 120 OC.  When the crosslinking temperature of trimer-crosslinker system increased from 120 OC to 140 OC, the induction time for curing decreased around three times.  The reaction between epoxidized oil and trimer acid was obviously accelerated by using 4-methyl amino pyridine as a catalyst.  Increasing the catalyst content induced a monotonically reduction in induction time of curing process.  The induction time of the reaction between epoxidized linseed oil and trimer acid with 2% catalyst at reaction temperature of 120 OC was only 18 minutes, which was significantly shorter than that of an uncatalyzed systems around seven times.