Effect of hot pressing/melt mixing on the properties of thermoplastic polyurethane

• Published in: Macromolecular research Vol. 17; no. 8; pp. 616 - 622
• Main Authors: Lee, Young-Hee, Kang, Bo-Kyung, Kim, Han-Do, Yoo, Hye-Jin, Kim, Jung-Soo, Huh, Jae-Ho, Jung, Young-Jin, Lee, Dong-Jin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2009; 한국고분자학회
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Nanochemistry; Nanotechnology; Physical Chemistry; Polymer Sciences; Soft and Granular Matter; 고분자공학; TPU scrap; recycle; thermoplastic polyurethane (TPU); thermal degradation; melt mixing
• ISSN: 1598-5032; 2092-7673
• DOI: 10.1007/BF03218918

In-depth understanding of the influence of hot pressing and melt processing on the properties of thermoplastic polyurethane (TPU) is critical for effective mechanical recycling of TPU scraps. Therefore, this study focused on the effects of hot pressing and melt mixing on molecular weight (MW), polydispersity index (PDI), melt index (MI), characteristic IR peaks, hardness, thermal degradation and mechanical properties of TPU. The original TPU pellet (o-TPU) showed two broad peaks at lower and higher MW regions. However, four TPU film samples, TPU-0 prepared only by hot pressing of o-TPU pellet and TPU-1, TPU-2 and TPU-3 obtained by hot pressing of melt mixed TPUs (where the numbers indicate the run number of melt mixing), exhibited only a single peak at higher MW region. The TPU-0 film sample had the highest M n and the lowest PDI and hardness. The TPU-1 film sample had the highest M w and tensile modulus. As the run number of melt mixing increased, the peak-intensity of hydrogen bonded C=O stretching increased, however, the free C=O peak intensity, tensile strength/elongation at break and average MW decreased. All the samples showed two stage degradations. The degradation temperatures of TPU-0 sample (359 °C and 394 °C) were higher than those of o-TPU (342 °C and 391 °C). While all the melt mixed samples degraded at almost the same temperature (365 °C and 381 °C). The first round of hot pressing and melt mixing was found to be the critical condition which led to the significant changes of M n / M w /PDI, MI, mechanical property and thermal degradation of TPU.