			Home About us Contact

Elastomeric Properties (elastomeric + property)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Gradient graft copolymers derived from PEO-based macromonomers

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2006
Dorota Neugebauer
Abstract Atom transfer radical polymerization (ATRP) of two poly(ethylene oxide) (PEO) macromonomers, with different polymerization degrees (DPn) and different end groups, was conducted in solution via the grafting through method. Selection of a PEO methacrylate with a methyl end-group (PEOMeMA, DPPEO = 23) and a PEO acrylate end-capped by a phenyl ring (PEOPhA, DPPEO = 4) for the copolymerization led to a spontaneous gradient of PEO grafts along the copolymer backbone. Such a composition was formed because of significantly different reactivities of the two PEO macromonomers. The resulting copolymer has PEOMeMA at one end of the polymer chain, gradually changing through hetero-sequences of PEOPhA at the other chain end. An increase in the initial feed ratio of PEO acrylate reduced the rate of change in the shape of the gradient. Amorphous,crystalline structure in the copolymers was demonstrated by DSC and WAXS. The mechanical measurements of copolymers consisting of an amorphous PEOPhA and crystallizable PEOMeMA segments indicated elastomeric properties in the range of a soft rubber (G, , 104 Pa, G, , G,). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1347,1356, 2006 [source]

Time-Temperature Creep Behaviour of Poly(propylene) and Polar Ethylene Copolymer Blends

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2007
Antonietta Genovese
Abstract Polymers commonly undergo deformation under an applied stress over their lifetime; some deformations are irrecoverable once the source of stress is removed. Therefore an understanding of the response of a polymer can be achieved by investigating the viscoelastic properties using creep experiments, where the behaviour can be monitored under small deformational loads. Poly(propylene) (PP) was blended with a polar elastic, thermoplastic, poly[ethylene- co -(methyl acrylate)] (EMA), to toughen the matrix. EMA formed a dispersed phase in PP that maintained its strength through its crystallinity rather than crosslinking. EMA can form a compatible interface with PP through inclusion of maleated-PP as a compatibiliser. The viscoelasticity of the PP,EMA blends, particularly the creep behaviour is an important factor if the properties of PP are to be maintained. The creep and recovery of PP,EMA blends with varying compositions were investigated under different loads and number of cycles. High EMA content provided an alternative deformation pathway due to its elastomeric properties. The experimental creep behaviour has been evaluated using the 4-element model with some limitations evident in the viscoelastic transitional region. [source]

Effect of processing variables on the linear viscoelastic properties of SBS-oil blends

POLYMER ENGINEERING & SCIENCE, Issue 12 2001
F. J. Navarro
Block copolymers, especially styrene-butadiene-styrene three-block copolymers (SBS), are recognized as especially effective asphalt modifiers because of their thermoplastic elastomeric properties. The concentration of copolymer, its ability to swell by the maltenic oils, and the processing variables are essential in the development of a three-dimensional network in the polymer-rich phase that enhances the vis-coelastic properties of these modified binders. This swollen polymer phase may influence the mechanical properties of the modified bitumens and synthetic binders. This paper deals with the influences that processing variables exert on the linear viscoelastic properties of oil/SBS mixtures in a wide range of temperatures. From the experimental results obtained we may conclude that most of the oil/SBS blends studied are highly structured thermoplastic gels above a critical SBS concentration that depends upon temperature, time of processing and surrounding atmosphere. [source]

Biomacromolecular engineering: design, synthesis and characterization.

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9-10 2006
One-pot synthesis of block copolymers of arborescent polyisobutylene, polystyrene
Abstract Novel arborescent block copolymers comprising of an arborescent rubbery polyisobutylene (PIB) midsegment and glassy polystyrene (PSt) end blocks were prepared by sequential addition of monomers. Synthesis was conducted by the use of 4-(2-methoxyisopropyl) styrene as an inimer-type initiator in conjunction with titanium tetrachloride (TiCl4) in 60:40 (v/v) methylcyclohexane/methyl chloride solvent mixture. Isobutylene was polymerized for 1,2,hr and then prechilled styrene in the same solvent mixture was sequentially added with select additives to the reaction flask. The recovered block copolymers were purified and then characterized by 1H-NMR, size exclusion chromatograph (SEC), tensile test, atomic force Microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Samples with 16.4,32.8,wt% PSt and Mn,=,47,600,125,900,g/mol (Mw/Mn,=,2.02,4.45) displayed thermoplastic elastomeric properties with 5,9.2,MPa tensile strength and 490,920% elongation. The arborescent block copolymers showed surface morphologies ranging from spherical to cylindrical/lamellar nanometer-sized discreet PSt phases dispersed in a continuous PIB matrix, with a 10,nm PIB layer on the surface. Drug release profiles of paclitaxel from two arborescent blocks were found to be similar to that measured from Translute®. Copyright © 2006 John Wiley & Sons, Ltd. [source]