Morphology and mechanical behavior of block polymers

Abstract

The morphology of solution cast films of butadiene and styrene block polymers in both stretched and unstretched state has been studied by electron microscopy, and has been related to the mechanical behavior of these materials. These micrographs confirm the indications from dynamic properties that this material consists of a two‐phase system in which the relationship between the phases is sensitive to the solvent system used in casting. Although the basic morphological unit is a polystyrene sphere of 100 Å diameter dispersed in a matrix of polybutadiene, the interaction between spheres is complex. These spheres are more deformable than would be predicted from their glass transition temperature. The dynamic mechanical properties, stress‐strain properties, and stress relaxation properties of block polymers of styrene and dienes can be explained in terms of the morphology and changes of morphology on stretching in the electron microscope.

Domain structure and time‐dependent properties of a crosslinked urethane elastomer

“…The reason is that the high electron density stain preferentially attaches to the double bonds in the polybutadiene soft segment. 21 The electron micrograph of stained elastomer shows greatly enhanced contrast and therefore demonstrates the presence of domain structure (Fig. 6b).…”

Morphology of pyrolysed polystyrene–isoprene–styrene and polystyrene–butadiene–styrene block copolymers

“…11,12 Morphological behavior of polystyrene-isoprenestyrene (SIS) and polystyrene-butadiene-styrene (SBS) polymers has been studied in the past. 13,14 Photo and thermal degradation of these block copolymers are well documented in the literature. 15,16 However, very little attention has been given toward the understanding of their surface changes upon pyrolysation in a muffle furnace.…”

The molecular theory of viscoelasticity for thermoplastic elastomer SBS (SIS) at large deformations

“…The relationship between the structure and the elastic properties has been studied by many researchers [1 -7], and a large number of experimental data of stress to strain have been accumulated [ 4 -7 ] . But these experimental data are usually treated by semiempirical formulas; one is Mooney-Rivlin [8] or *) Project supported by the National Natural Foundation of China Guth-Smallwood [9] equation (1) or (2); the other is Tschoegl [10] relation (3) or (4). ' f = 2(C 1 + C2/~.)…”

“…The perfection and degree of phase separation have been found to be important to the properties of polymers and are dependent on molar composition, synthesis procedure, thermal history, the molecular weight (and MW distribution), the nature of the selective solvent and their evaporation rate, the successive deformations and their storage conditions (i.e., time, temperature), impurity, as well as diluent [1][2][3][4][5][6][7].…”