Structure-property relationships of poly(urethane urea)s with ultra-low monol content poly(propylene glycol) soft segments. I. Influence of soft segment molecular weight and hard segment content

2002 ◽  
Vol 84 (2) ◽  
pp. 229-243 ◽  
Author(s):  
Matthew J. O'Sickey ◽  
Bruce D. Lawrey ◽  
Garth L. Wilkes
Keyword(s):  
Molecular Weight ◽  
Propylene Glycol ◽  
Hard Segment ◽  
Soft Segment ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Hard Segment Content ◽  
Soft Segments ◽  
Poly Propylene

Infrared study of the photochemical behaviour of aromatic Poly (ether urethanes)

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
G. Mendikute ◽  
L. Irusta ◽  
M.J. Fernández-Berridi
Keyword(s):  
Molecular Weight ◽  
Ftir Spectroscopy ◽  
Propylene Glycol ◽  
Hard Segment ◽  
Chemical Nature ◽  
Infrared Study ◽  
Hard Segment Content ◽  
Photochemical Behaviour ◽  
Poly Propylene ◽  
Different Molecular Weight

AbstractPoly(ether urethanes) based on aromatic diisocyanates and poly(propylene glycol) of different molecular weight and different hard segment content have been synthesised. The extent of the photooxidation of UV exposed samples has been evaluated by FTIR spectroscopy. The results proved that both the isocyanate chemical nature and polyol molecular weight play an important role in the photooxidation behaviour of these systems.

Structure–property relationships and melt rheology of segmented, non-chain extended polyureas: Effect of soft segment molecular weight

Polymer ◽  
2007 ◽  
Vol 48 (1) ◽  
pp. 290-301 ◽  
Author(s):  
Sudipto Das ◽  
Iskender Yilgor ◽  
Emel Yilgor ◽  
Bora Inci ◽  
Ozgul Tezgel ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Soft Segment ◽  
Structure Property ◽  
Melt Rheology ◽  
Structure Property Relationships

Polyurea Synthesis and Properties as a Function of Hard-Segment Content

1988 ◽  
Vol 61 (1) ◽  
pp. 86-99 ◽  
Author(s):  
Z. S. Chen ◽  
W. P. Yang ◽  
C. W. Macosko
Keyword(s):  
Molecular Weight ◽  
Hard Segment ◽  
Soft Segment ◽  
Tensile Elongation ◽  
Mechanical And Thermal Properties ◽  
Solution Polymerization ◽  
Dynamic Mechanical ◽  
Hard Segment Content ◽  
Mechanical Modulus ◽  
Dynamic Mechanical Modulus

Abstract High-molecular-weight linear polyureas of different hard-segment content are obtained with a two-step solution polymerization. Elimination of water, careful choice of solvent, reactant concentration, and good control of reaction temperature are essential to obtain satisfactory results. We have studied the influence of the hard-segment content on the mechanical, dynamic-mechanical, and thermal properties of these solution polymerized amine-terminated polypropylene-oxide-based thermoplastic polyureas. Two-phase morphology is predominant within the range of the hard-segment concentration studied. Inversion of the continuous and dispersed phase might occur in the polyurea series at about 60 wt.% of hard segment. This changes the nature of the polyureas from a tough elastomeric material to a more brittle, high-modulus plastic. The modulus of the rubbery plateau measured from dynamic-mechanical spectra increases with hard-segment concentration due to the reinforcing effect of hard-segment domains. However, continuous improvement in dynamic-mechanical modulus is not significant when the hard segment is above 50 wt.% due to higher degree of phase mixing in high hard-segment concentration systems. The amount of solubilized hard segment in the soft-segment phase in these polyureas is limited as judged from the relatively constant soft-segment Tg. However, the extent of phase separation, as determined by the heat capacity change ΔCp across the soft-segment Tg, decreases with increasing hard-segment content. The same characterizations and analyses have also been carried out on a series of RIM produced polyurea samples of the same composition. Great difference in properties is observed in comparison of these two sets of samples due to their different synthesis routes. In general, samples produced by RIM exhibit lower molecular weight, lower dynamic-mechanical modulus, higher soft-segment Tg, more phase-mixed, and more tensile elongation than those synthesized by solution polymerization. The detailed comparison will be treated in a separate paper.

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