On the Configurational Statistics of Ethylene-Propylene Copolymers
نویسنده
چکیده
Mean-square unperturbed dimensions {r2)0 and their temperature coefficient d In{r2)0/dT have been calculated for ethylene-propylene copolymers by means of the rotational isomeric state theory of chain molecules. Conformational energies required in the analysis are shown to be readily obtained from previous analyses of polyethylene and polypropylene, without additional approximations. Results thus calculated are reported as a function of chemical composition, chemical sequence distribution, and stereochemical composition of the propylene sequences. It is shown that {r2)0 and d In (r2 )0/ d T for these copolymer chains should be most sensitive to chemical sequence distribution in the case where propylene sequences are highly isotactic in stereochemical structure. Calculations carried out using values of these variables thought to be appropriate for ethylene-propylene polymers experimentally investigated give values of d In (r2)0/dT which are in good agreement, in general, with those obtained from previously published force-temperature measurements on elongated networks of ethylene-propylene chains.
منابع مشابه
Quantification of identical and unique segments in ethylene-propylene copolymers using two dimensional liquid chromatography with infra-red detection
Hyphenating High Temperature High Performance Liquid Chromatography (HT-HPLC) with High Temperature Size Exclusion Chromatography (HT-SEC) (High Temperature Two Dimensional Liquid Chromatography (HT-HPLC x HT-SEC or HT 2D-LC)) leads to an isocratic elution in the second dimension, which in turn enables to use IR detector (quantitative detection) for monitoring the eluting polymers. Experimental...
متن کاملIsotactic and Syndiotactic Alternating Ethylene/Propylene Copolymers Obtained Through Non-Catalytic Hydrogenation of Highly Stereoregular cis-1,4 Poly(1,3-diene)s.
The homogeneous non-catalytic hydrogenation of cis-1,4 poly(isoprene), isotactic cis-1,4 poly(1,3-pentadiene) and syndiotactic cis-1,4 poly(1,3-pentadiene) with diimide, formed by thermal decomposition of para-toluenesulfonylhydrazide, is examined. Perfectly alternating ethylene/propylene copolymers having different tacticity (i.e., isotactic and syndiotactic), which are difficult to synthesize...
متن کاملPoly(ethylene oxide)–Poly(propylene oxide)-Based Copolymers for Transdermal Drug Delivery: An Overview
Amphiphilic poly(ethylene oxide)–poly(propylene oxide) (PEO–PPO)-based copolymers are thermoresponsive materials having aggregation properties in aqueous medium. As hydrosolubilizers of poorly water-soluble drugs and improved stability of sensitive agents, these materials have been investigated for improvement in solubility, stability, release and bioavailability of drugs. The goal of the prese...
متن کامل