Study of the chain extension of PET during reactive extrusion

The chang of [η] and carboxyl value of PET pre-and post-reactive extrusion process was studied carefully based on the feeding of 2,2'-Bis(2-oxazoline)(BOZ)and Pyromellitic dianhydride(PMDA)as chain extenders.The experiments results showed that the chain extension effects of BOZ was not obvious,while PMDA can increase the [η] of PET to a great extent,but the carboxyl value of PET was high.The PET products with high [η] and low carboxyl value can be obtained by the combinated using of BOZ and PMDA.The chain extension results were optimum.The PET products with [η](0.90 dL/g) and carboxyl value(25 mol/t) can be obtained at the reactive condition as follows:the reaction stage temperature at 260 ℃,the screw rotation speed is 45 r/min,the reaction stage pressure is 1kPa,the mass fraction of both BOZ and PMDA is 0.2%.