Premium
Rheological properties and thermal transitions in millable polyurethane fluoroelastomers
Author(s) -
Turri Stefano,
Levi Marinella,
Cristini Marco,
Sanguineti Aldo
Publication year - 2005
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1752
Subject(s) - differential scanning calorimetry , prepolymer , polyurethane , materials science , hexamethylene diisocyanate , rheology , polymer chemistry , monomer , dynamic mechanical analysis , glass transition , copolymer , isothermal process , amorphous solid , viscosity , shear thinning , thermodynamics , polymer , chemical engineering , composite material , chemistry , crystallography , engineering , physics
A series of segmented polyurethane fluoroelastomers based on dimethylol‐terminated perfluoropolyethers (PFPEs), aliphatic diisocyanates and allyl functionality is presented. Depending on the type of diisocyanate monomer used, it was found that quite different prepolymer molecular weights were achieved. Thermal analysis by differential scanning calorimetry showed formation of polyphasic copolymers, either amorphous or semi‐crystalline depending on the monomer structure. Rheological measurements showed that much higher zero‐shear viscosity, a shorter Newtonian plateau and more marked shear thinning behaviour were achieved with polyurethanes based on hexamethylene diisocyanate (HDI) or H 12 ‐MDI monomers. Isothermal viscosity curves were fitted with either three‐ or two‐parameter empirical models, and relaxation times of the structures were estimated at the temperature of 120 °C. Copyright © 2004 Society of Chemical Industry