TITLE:
Rheological and Thermal Behavior of High-Density Polyethylene (HDPE) at Different Temperatures
AUTHORS:
Cynthia D’Avila Carvalho Erbetta, Getúlio F. Manoel, Ana Paula Lelis Rodrigues Oliveira, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
KEYWORDS:
HDPE, Rheology, Degradation, DSC, FTIR
JOURNAL NAME:
Materials Sciences and Applications,
Vol.5 No.13,
November
26,
2014
ABSTRACT: In the present work, rheological properties of HDPE samples were measured at temperatures of 150°C, 190°C and 230°C. It was shown, by oscillatory tests, at low frequencies, that, for temperatures of 150°C and 190°C, there was a predominance of the viscous behavior over the elastic one. At 230°C, there was a predominance of the elastic contribution, and there was an increase of the molar mass compared with the ones obtained from the tests at 150°C and 190°C. The results obtained from the temperature ramp oscillatory test showed that, up to around 248°C, the viscous behavior prevailed, the opposite being observed at higher temperatures. At 230°C the sample showed significantly lower values of strain when compared with the ones observed at 150°C and 190°C. Oxidative induction time (OIT), melting point and degree of crystallinity were determined by differential scanning calorimetry (DSC). The DSC results and the rheological measurements showed a completely different behavior for the HDPE samples at 230°C compared with the 150°C and the 190°C ones, suggesting that HDPE, at the temperature of 230°C, underwent thermo-oxidative degradation with the initial predominance of crosslinking.