Thermal effects under elastic and plastic deformation of polyethylene

Thermal effects occurring under tensile deformation were analyzed for polyethylene samples with different level of crystallinity and dimensions. Temperature changes were measured by IR camera at all stages of deformation (from elastic region until fracture) at various strain rates. At the initial st...

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Bibliographic Details
Published in:Polymer (Guilford) 2015-01, Vol.56, p.416-427
Main Authors: Guseva, M.A., Gerasin, V.A., Garishin, O.K., Shadrin, V.V., Plekhov, O.A., Pawlak, A.
Format: Article
Language:English
Subjects:
Adiabatic flow
Crystallinity
Deformation
Elastic and plastic deformation
Elastic deformation
Energy consumption
Necking
Necks
Polyethylene
Polyethylenes
Strain rate
Thermal phenomena
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Summary:Thermal effects occurring under tensile deformation were analyzed for polyethylene samples with different level of crystallinity and dimensions. Temperature changes were measured by IR camera at all stages of deformation (from elastic region until fracture) at various strain rates. At the initial stage of drawing energy is consumed and temperature of the polymer slightly decreases (endothermic effect). Onset of necking gives rise to intensive heat generation and substantial increase in temperature in the element where neck originates. When front of neck moves away, analyzed element begins to cool down. At the region of strain hardening a new increase in temperature is observed. Maximal degree of heating during necking was found to depend on the level of crystallinity of the polymer, tensile rate and the speed of the front of neck. Calculations were conducted to estimate the maximum adiabatic temperature provided no energy is dissipated outside the heat source. Adiabatic temperature was compared with values of temperature registered in the experiment for specimens with different dimensions. It was found that starting from strain rate 500%/min deformation process of rather “large” samples proceeds nearly adiabatically. [Display omitted] •We examine thermal effects during deformation of semi-crystalline polymers.•Slight endothermic effect in the area of Hooke's strains before yielding.•Large exothermic effect in the yield region where neck is formed.•Increasing level of crystallinity will increase temperature rise.•Temperature profile during propagation of neck is found to be a decaying exponent.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2014.11.041