Thermoplastic urethane elastomers. VI. Dilute solution properties in various solvents

Abstract

A thermoplastic urethane elastomer prepared from a polycaprolactone diol, 4,4′‐diphenylmethane diisocyanate, and 1,5‐pentanediol was fractionated and the solution properties of the fractions were characterized in terms of viscosity and sedimentation. Mark‐Houwink relations were established for data obtained at 30° in various solvents: In dimethylacetamide, tetramethylurea, and N‐methyl pyrrolidone, the value of Kθ increased systematically in the range (1.7 to 2.0) × 10−3. Lower values of Kθ were obtained in dimethylformamide (0.8 × 10−3) and meta‐cresol (0.9 × 10−3). The molecular expansion coefficients in the various solvents were approximated from the experimental viscosity data. Short‐range interactions between the solvent molecules and polymer chains are suggested as possible causes for differences in the hydrodynamic parameters.

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(ϵ‐caprolactone)–poly(ethylene oxide) diols and various chain extenders

“…The following constants were used in the MarkHouwink equation for calculation of the molecular weight: K = 6.80 × 10 −5 dL/g and ␣ = 0.86. 37 In addition, the molecular weight distribution and relative molecular weights were determined by size exclusion chromatography analyses carried out on a Waters modular gel permeation chromatography system. The system consisted of a 510 pump, a U6K injector, a 410 refractive-index detector, and a set of three linear Waters Styragel columns (10 5 and 10 4 nm) maintained at 60°C.…”

Synthesis and Characterization of N,N',N'',N'''-Tetrasalicylidene-3,3'-diaminobenzidine Schiff-Base Coordination Polyelectrolytes of Yttrium(III), Lanthanum(III), Gadolinium(III), and Ytterbium(III)

“…The a value of 0.51 is quite close to 0.50, the value expected for a solvent, which means that at 30 °C NMP is not a good solvent for this type of polyelectrolyte.38'41 The K value of 8.1 x 10-2 cm3/g is consistent with polymer-solvent interactions. 42 This result is quite different from those for the analogous neutral coordination polymers of cerium(IV)6'7 and zirconium! IV).32 For them, higher a values (0.65-0.79) were found.…”

Trends in PSA, age and prostate cancer detection among black and white men from 1990‐2006 at a tertiary care center

“…The number–average molecular weight of the ester type of MM4510 shape memory polymer was found to be approximately 90,000 using K and α values of a polyester based polyurethane from the literature 23. The DSC scans (Fig.…”