Robert J. Samuels

Quantitative structural characterization of the mechanical properties of isotactic polypropylene

Abstract This investigation introduces quantitative morphological criteria for defining the structural state of a polymer sample and develops a general structural state deformation model for characterizing mechanical behavior. This general model discards the present fragmented view of the autonomy of observed mechanical processes (yielding, fracture, recovery, etc.) and brings the fabrication process, the mechanical tests, and even the construction of the sample (fiber or film) into focus as simply different aspects of a single process of deformation. The fabrication, fracture, yielding, and recovery behavior of two series of uniaxially drawn isotactic polypropylene films and two series of drawn isotactic polypropylene fibers, totaling thirty different structural states, have been deter-mined. The structural state of each of these samples is known quantitatively. The measurements were made over a range of strain rates from 1 to 1,000,000%/min and temperatures from 23° to -196°C. This study has resulted in...

Quantitative structural characterization of the deformation and shrinkage of isotactic polypropylene fibers and films

Abstract A quantitative determination has been made of the structural elements which control deformation and shrinkage processes in isotactic polypropylene fibers and films. It is found that strain processes such as fabrication draw and shrinkage are controlled by the noncrystalline region of this highly crystalline polymer. Quantitative structure-property correlations are obtained for the polymer, which reveal the interactions between temperature, strain, and orientation. The thermal activation energy of the noncrystalline chains is also determined from these solid-state structure measurements.

A quantitative evaluation of the structure and properties of the methyl ester of divinyl ether - maleic anhydride 1:2 copolymer

Abstract The methyl ester of divinyl ether—maleic anhydride 1:2 copolymer (DME) has been used as a molecular probe to identify the structure of DIVEMA (divinyl ether—maleic anhydride 1:2 copolymer). Solution light scattering, gel permeation chromatography, and intrinsic viscosity measurements have shown that tetrahydrofuran at 30°C is a theta solvent for DME, and that DME has a random coil conformation with possible long chain branching at higher molecular weights. Determination of the characteristic ratio of DME required identification of its molecular structure. Molecular model studies revealed that the bulky methyl ester groups cause much more steric hindrance in the generally accepted tetrahydropyran structure of DME than in an alternative tetrahydrofuran structure. This observation, together with the polymer solution measurements, indicates the latter structure is more in accord with experimental data, suggesting that both DME and the parent DIVEMA contain tetrahydrofuran in their structures.