AbstractsBiology & Animal Science

"Intrinsic viscosity measurements were performed on linear polyethylene (Marlex 6009) in decalin at 135ºC and in diphenyl ether at 163.9ºC. Molecular weights ranging from 3x10³ to 35x10⁴ were studied. It was found that for linear polyethylene of molecular weight up to 35x10⁴, the tedious intrinsic viscosity measurement could be replaced by inherent viscosity measurement at a concentration of 0.1 grams per deciliter. The effect of shear on viscosities measured in decalin increased as the molecular weight of the sample increased. The shear rate effects on intrinsic viscosities were negligible. On the other hand, the shear rate effect on the Huggins' constant was surprisingly high considering the small shear rate effect on viscosities but still negligible. The validity of the Huggins equation was tested. It was found that the equation holds to [η]C≈0.75 or η[subscript rel] <1.9 for all polyethylene samples except the highest molecular weight sample (35x10⁴). For samples of M[subscript w]=6,200 to 145,000, the Huggins' constants were sensitive to the molecular weight of the sample in poor solvents. The Mark-Houwink expression for the linear polyethylene samples (0.62<M[subscript w] x10⁻⁴ <35.0) in decalin at 135ºC was: [η]=5.72x10⁻⁴M[subscript w] superscript 0.70]. In diphenyl ether at 163.9ºC, a theta solvent, [n][subscript Θ] =26.1x10⁻⁴ M[subscript w] [superscript 0.5] was observed for samples (0.62<M[subscript w] x 10⁴<5.8). The dimensionless ratio (r[overscore 2 over o])/n[cursive l]² calculated from the intrinsic viscosity of samples in the Θ solvent was 6.06, and a value 1.03x10⁻¹⁶ for (r[2 over o])/M was obtained for all the samples. The values are close to the values obtained by Chiang and support the theoretical calculation done by Hoover and Nagai" – Abstract, leaf iii.