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Influence of Molecular Weight on the Creep Resistance of Almost Molten Polyethylene Blends
Author(s) -
Andersson Mattias G.,
Städler Roman,
Hagstrand PerOla,
Gkourmpis Thomas,
Andersson Mats R.,
Müller Christian
Publication year - 2018
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201700072
Subject(s) - low density polyethylene , creep , polyethylene , materials science , high density polyethylene , composite material , linear low density polyethylene , polymer chemistry
The most common route to improve the creep resistance of low density polyethylene (LDPE) is crosslinking, which however results in volatile decomposition products that must be removed. Blends of LDPE and an additive‐like amount of a linear polyethylene are found to offer improved creep resistance. Above the melting temperature of LDPE, T m ≈ 111 °C, a load‐bearing network of higher‐melting crystallites—connected through tie chains and trapped entanglements—provides additional form stability. The molecular weight of the linear polyethylene is found to be critical for the ability to arrest creep, which is correlated with the probability of tie chain formation as well as cocrystallization of the two polyethylenes. A number of high‐density polyethylenes (HDPE) and one ultrahigh molecular weight polyethylene (UHMW‐PE) are explored. For blends of LDPE and 2 wt% of the linear polyethylene, an HDPE with a weight‐average molecular weight M w of 16 kg mol −1 is found to be sufficient to arrest creep at 115 °C. Further improvement in terms of creep resistance is obtained in case of UHMW‐PE with creep fracture occurring only at a stress of 12 kPa at 115 °C.