Effect of Molecular Weight on Mechanical Behaviour of Segmented Polyurethanes

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Title:Effect of Molecular Weight on Mechanical Behaviour of Segmented Polyurethanes
Creators:
Ilavský, Michal
Fähnrich, Jaromír
Pakula, Tadeusz
Lantman, Christopher
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 60, 11, pp. 1925-1934

Abstract

<p>The effect of molecular weight of polyurethanes on their dynamic mechanical and ultimate behaviour was investigated in wide frequency and temperature ranges. The polyurethanes were prepared from α,ω-dihydroxy-poly(oxypropylene), 1,4-butanediol, 1-butanol and 4,4'-dicyclohexylmethane diisocyanate at constant stoichiometric molar ratio of OH and NCO groups. Molecular weight (MW) of the copolymers was varied by replacing partly the butanediol by equivalent amounts of butanol; the calculated values of MW ranged from 6 000 to infinity. In all samples the constant soft-segment concentrations (~50 wt.%) were obtained. Two transition regions located around -30 °C and 70 °C, corresponding to the soft polyether and hard polyurethane domains, respectively, were observed with all samples in the temperature dependences of both components of the dynamic modulus measured at 1 Hz. Due to high miscibility of the phases, both transitions overlap; the two-phase character of the structure increases with decreasing MW. At <i>T</i> &gt; 120 °C the samples are homogeneous and the frequency-temperature superposition could be applied. Quenching of the samples from 150 °C down to -80 °C preserves quasi-homogeneous structure; the rate of re-establishment of the two-phase structure increases with decreasing MW. The ultimate properties, strain-at-break and tensile strength measured at room temperature decrease with decreasing MW.

Title:Effect of Molecular Weight on Mechanical Behaviour of Segmented Polyurethanes
Creators:
Ilavský, Michal
Fähnrich, Jaromír
Pakula, Tadeusz
Lantman, Christopher
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:60
Number:11
Page Range:pp. 1925-1934
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19951925UNSPECIFIED
ID Code:880
Item Type:Article
Deposited On:06 Feb 2009 17:04
Last Modified:06 Feb 2009 16:04

Citation

Ilavský, Michal; Fähnrich, Jaromír; Pakula, Tadeusz; Lantman, Christopher (1995) Effect of Molecular Weight on Mechanical Behaviour of Segmented Polyurethanes. Collection of Czechoslovak Chemical Communications, 60 (11). pp. 1925-1934. ISSN 0010-0765

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