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Effects of polymerization catalyst technology on the melt processing stability of polyethylenes. part 2. single stabilizer performance
Author(s) -
del Teso Sánchez Karmele,
Allen Norman S.,
Liauw Christopher M.,
Edge Michelle,
Johnson Brian,
Catalina Fernando,
Corrales Teresa
Publication year - 2012
Publication title -
journal of vinyl and additive technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 35
eISSN - 1548-0585
pISSN - 1083-5601
DOI - 10.1002/vnl.20288
Subject(s) - stabilizer (aeronautics) , catalysis , thermal stability , materials science , phenols , steric effects , polymer , polymerization , high density polyethylene , polymer chemistry , organic chemistry , chemical engineering , chemistry , composite material , polyethylene , mechanical engineering , engineering
Abstract The effects of a range of thermal and light stabilizers on the melt stability (investigated via multiple pass extrusion) and color stability of three different polyethylenes (PEs) were examined. The PEs varied in terms of the catalyst system used to synthesize the polymers and included an HDPE produced by using a chromium‐based Phillips catalyst and two LLDPEs produced via chromium‐based metallocene and titanium‐based Ziegler‐Natta catalysts. The additive types included a range of phenolics of different functionality, phosphites, hindered piperidines, an hydroxylamine, and Vitamin E. The results obtained for the three PEs confirmed that primary antioxidants (AOs) such as highly hindered and less, hindered phenols or hydroxylamines promoted good melt stability but in some cases tended toward yellowing. The secondary AOs such as the phosphites or thioethers behaved in the opposite way; color suppression was good, but melt stabilization was poor. It was also shown that for different types of phenols (all with similar molar activity), reducing steric hindrance to the phenolic OH enhanced the tendency to form chromophoric groups and hence color led to better efficiency than high hindrance. Those phenol with higher molar activity (mol OH/kg AO) showed the best processing performance. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers