Mechanical property modification and morphology of poly(styrene-b-hydrogenated butadiene-b-styrene)/poly(hydrogenated butadiene) blends

Journal Article · Mon Sep 12 00:00:00 EDT 1994 · Macromolecules; (United States)

DOI:https://doi.org/10.1021/ma00097a012· OSTI ID:7180977

Baetzold, J P; Gancarz, I; Quan, X; Koberstein, J T ^[1]

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1. Univ. of Connecticut, Storrs, CT (United States)

The mechanical properties and morphology of a series of triblock copolymer blends with midblock associating homopolymers of varying molecular weight (Mw) have been characterized. The symmetric triblock copolymer studied contains polystyrene endblocks and midblocks of hydrogenated poly(1,2-butadiene) and is mixed with hydrogenated poly (1,2-butadiene) homopolymers of Mw both below and above that of the copolymer midblock. The rubbery plateau modulus determined by dynamic mechanical spectroscopy increases with increasing Mw of the homopolymer at fixed overall homopolymer content. At fixed Mw, the composition dependence of the plateau modulus is complex and shows unusually synergistic behavior. For high Mw homopolymers the plateau modulus increases initially upon homopolymer addition. Small angle neutron scattering and TEM are employed to determine the morphological changes. In all cases, the blends exhibit a lamellar microphase structure, with homopolymer macrophases apparent at high homopolymer contents. The apparent homopolymer solubility limits are found to be inversely related to the homopolymer Mw. The results indicate that the lamellar repeat distance decreases upon addition of the lowest Mw homopolymer and that the microdomains swell in blends containing homopolymers with Mw similar to that of the midblock sequence and are unchanged for high Mw homopolymers with negligible solubility. The results suggest that the interesting mechanical response of the blends can be explained by consideration of the changes in their entanglement structure resulting from confinement of the homopolymer chains within the highly constrained environment of the midblock lamellae.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7180977
• Journal Information: Macromolecules; (United States), Journal Name: Macromolecules; (United States) Vol. 27:19; ISSN MAMOBX; ISSN 0024-9297
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360603* -- Materials-- Properties
BUTADIENE
COPOLYMERS
DIENES
DISPERSIONS
ELECTRON MICROSCOPY
HYDROCARBONS
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSCOPY
MIXTURES
MOLECULAR MODELS
MOLECULAR WEIGHT
MORPHOLOGY
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYENES
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
SCATTERING
SMALL ANGLE SCATTERING
SYNTHETIC MATERIALS
TRANSMISSION ELECTRON MICROSCOPY