Preparation of HBPET and its application in recycled PET spinning

This study focuses on the modification of recycled poly (ethylene terephthalate) (RPET) with hyperbranched polyesters. The main objectives were to investigate the influence of hyperbranched polyester on the crystallization kinetics, rheological behavior, mechanical properties, dyeability and color fastness of the RPET fibers. Three different types of hyperbranched polyesters (AA-Ph-1, AA-Ph-2 and AA-Ph-3) with aromatic-aliphatic structure were synthesized by single step-melt polycondensation of adipic acid (AA) and phloroglucinol (Ph) at three different mole ratios (AA/Ph=A2: B3=1:1, 1:1.5 and 1:2. It was found that these hyperbranched polyesters show inherent viscosities ranging from 0.24 to 0.27 dL/g. The degree of branching was calculated to be 45–49% based on1H NMR and 13C NMR measurements. The thermogravimetric analysis (TGA) measurement revealed that hyperbranched polyester had10% weight loss at 324-377°C in nitrogen. Also three different types of hyperbranched polyester (IPA-Pe-1, IPA-Pe-2 and IPA-Pe-3) with aromatic-aliphatic structure was synthesized at three different mole ratios (pentaerythritol to isophthalic acid (1:1, 1:1.5, 1:2) respectively) by melting polycondens