Free-rotation dimensions of some polyurethane chains

Dostál, Jiřı́; Šimek, Lubomı́r; Bohdanecký, M.

doi:10.1016/s0032-3861(98)00254-7

Cited by 2 publications

(1 citation statement)

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“…On the other hand, we have not found C ∞ data of block PURs in the literature similar to those of our work. For a PUR obtained by the reaction of a diisocynate and a diol, Dostal et al22 report values of the steric factor between 1.07 and 1.32, depending on the employed configuration model. This corresponds to characteristic ratio values in the range of 4.58–6.97, which are lower than those obtained using Equation (4).…”

Section: Resultsmentioning

confidence: 99%

Novel Dynamic Viscoelastic Measurements of Polyurethane Copolymer Melts and Their Implication to Tack Results

Flórez¹,

Muñoz

Santamarı́a

2006

Macro Materials & Eng

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Summary: A series of polyurethane multiblock copolymers with different proportions of hard segments (urethane) to soft segments (polyadipate of hexane‐1,6‐diol), are investigated. Dynamic viscoelastic functions of homogeneous melts in the terminal zone are determined. For the first time, entanglement modulus values of such copolymers are reported, which allows estimation of the packing length. These parameters do not vary with changing the hard‐to‐soft segment ratio, a result that is explained by a compensating effect of the chain architecture. For samples of similar molecular weight, the relaxation time of the terminal zone increases as the hard‐to‐soft segment ratio augments. The adhesives obtained from PUR solutions show a correlation between the elastic modulus and the debonding stress‐strain curves in tack experiments.The storage modulus of the adhesives as a function of frequency at 70 °C.magnified imageThe storage modulus of the adhesives as a function of frequency at 70 °C.

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Section: Resultsmentioning

confidence: 99%