Paper Information

Journal:   IRANIAN POLYMER JOURNAL (ENGLISH)   2004 , Volume 13 , Number 5; Page(s) 363 To 370.
 
Paper: 

TIME-TEMPERATURE SUPERPOSITION AND DYNAMIC MECHANICAL PROPERTIES OF METALLOCENE POLYETHYLENES

 
 
Author(s):  RAZAVI NOURI M.*, HAY J.N.
 
* Department of Plastics, Faculty of Processing, Iran Polymer and Petrochemical Institute,Tehran, I.R. Iran
 
Abstract: 

This paper is devoted to the study of dynamic mechanical behaviour of two metallocene polyethylenes (m-PE). For this purpose two metallocene linear low density polyethylene (m-LLDPE) and very low density polyethylene (m-VLDPE) were used consisting of 3.3 mol% butyl and 6 mol% ethyl branches, respectively. The m-LLDPE showed three transitions at 31, -8 and –115°C attributed to the α, β and γ-transitions, respectively. The β-relaxation was observed as a shoulder on the α-relaxation peak. Studies on the m-VLDPE revealed no appreciable α-relaxation but an increased β-relaxation than that of the m-LLDPE. The effects of cooling rate and annealing were also investigated for the m-LLDPE. Slow cooled sample showed a higher α-relaxation temperature and was appreciably greater in breadth and area than that of the sample cooled in water. No appreciable shifts in either the a orβ-relaxation temperature were found by comparing loss modulus of quenched and annealed sample of the m-LLDPE. The time-temperature superposition principle was also found to be applicable to the α-relaxation process of the m-LLDPE and master curve was obtained at 80°C.

 
Keyword(s): METALLOCENE POLYETHYLENE, ENTHALPY OF RELAXATION, DMTA, SUPERPOSITION PRINCIPLE, MASTER CURVE
 
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