Development of New Masterbatches Containing Chain Extenders for Poly(ethylene terephthalate)

Abstract

New masterbatches for poly(ethylene terephthalate) (PET) which contain chain extenders such as 1,3‐phenylene‐bis‐oxazoline (1,3‐PBO) and/or N,N’‐carbonylbiscaprolactam (CBC) were developed. Here, cyclic poly(butylene terephthalate) (cPBT) which has no reactive end groups was used as masterbatch matrix. The main advantage of these masterbatches is their polyester‐based matrix, but the incorporated chain extenders are still active after the synthesis. The masterbatches were analyzed by TGA/FT‐IR, SEC, and 1H‐NMR analysis. They were applied to poly(ethylene terephthalate) during extrusion and, afterwards, also during spinning at high velocities on a pilot plant spinning device. The influence of these masterbatches on the quality of PET was analyzed by measurement of the screw force during extrusion, viscosimetry, SEC, and rheometry of the extruded compounds. The fibers spun on the pilot plant were analyzed by viscosimetry and by tensile strength measurements. The results show that the quality of polyester fibers spun from postconsumer PET can be improved by applying the developed masterbatches which contain chain extenders during spinning.