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The onset of thermal degradation dictates the maximum temperature at which a polymer can be used. It is an important limitation in how the polymer is manufactured and processed. For instance, polymers become less viscous at higher temperatures which makes injection moulding easier and faster, but thermal degradation places a ceiling temperature ...
Molten polymers are non-Newtonian fluids with high viscosities, and the interaction between their thermal and mechanical degradation can be complex. At low temperatures, the polymer-melt is more viscous and more prone to mechanical degradation via shear stress. At higher temperatures, the viscosity is reduced, but thermal degradation is increased.
The melting point for average commercial low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). ... The high-temperature properties of the polymer are ...
Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on atactic material and crystallinity. Syndiotactic PP with a crystallinity of 30% has a melting point of 130 °C (266 °F). [8] Below 0 °C, PP becomes brittle. [9]
PTFE is a thermoplastic polymer, which is a white solid at room temperature, with a density of about 2200 kg/m 3 and a melting point of 600 K (327 °C; 620 °F). [26] It maintains high strength, toughness and self-lubrication at low temperatures down to 5 K (−268.2 °C; −450.7 °F), and good flexibility at temperatures above 194 K (−79.15 ...
Glass transition (in polymer science): process in which a polymer melt changes on cooling to a polymer glass or a polymer glass changes on heating to a polymer melt. [8] Phenomena occurring at the glass transition of polymers are still subject to ongoing scientific investigation and debate.
The ability of the system to be readily deformed above its glass transition temperature allows polystyrene (and thermoplastic polymers in general) to be readily softened and molded upon heating. Extruded polystyrene is about as strong as an unalloyed aluminium but much more flexible and much less dense (1.05 g/cm 3 for polystyrene vs. 2.70 g/cm ...
The melting temperature of PLLA can be increased by 40–50 °C and its heat deflection temperature can be increased from approximately 60 °C to up to 190 °C by physically blending the polymer with PDLA (poly-D-lactide). PDLA and PLLA form a highly regular stereocomplex with increased crystallinity.