A random copolymer of ethylene oxide with CO2, namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm−1 and a Li transference number (t +) of 0.66 at 60 °C. To study ion‐conductive behavior of P(EC/EO)‐based electrolytes, the Fourier transform infrared (FT‐IR) technique is used to analyze the interactions between Li+ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li+ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t + for polymer electrolytes. High‐performance P(EC/EO) electrolyte is expected to be a candidate material for use in all‐solid‐state batteries.
The investigation of the intermolecular composition distribution of an ethylene/1-hexene copolymers using DSC method has been
carried out. The known methods: step crystallization (SC) and successive self-nucleation/annealing (SSA) have been adapted
for this purpose, and particularly, the optimal condition of the process have been chosen to enable the best fractional crystallization
of the copolymer. The method has been applied for fractionation of two ethylene/1-hexenecopolymers synthesized with supported
vanadium and zirconocene catalysts and having similar concentrations of 1-hexene. Although metallocene catalysts are known
from their more homogeneous structure of active sites in comparison to multi-site Ziegler–Natta catalysts, the copolymers
obtained over both catalytic systems gave DSC curves resolved into several peaks but with different melting points. Using
the Thomson–Gibbs equation, comparable average lamellar thickness of the separated peaks has been calculated. The amounts
of copolymer fraction with defined lamellar thickness have been determined. It was obtained that the copolymer produced from
the metallocene system contains a thinner and more homogeneous lamella thickness than that obtained with Ziegler–Natta vanadium
catalyst supported on the same carrier.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Specific heat capacities of a homogeneous ethylene-1-octene copolymer were measured by adiabatic calorimetry in the temperature
range from 5 to 400 K (stepwise heating at averaged rates of approximately 1 to 34 K h–1, after cooling at rates in the range from 8 K h–1 to 4 K min–1). The glass transition takes place from roughly 205 to225 K and is centred around approximately 215 K. At the latter temperature,
also the temperature drifts during the stabilisation periods are at maximum. Clearly, with devitrification above 215 K also
melting sets in. Using two sets of reference data (one for branched and linear polyethylenes, BPE, and the other for strictly
linear polyethylene, LPE)for completely crystalline and for completely amorphous material, the crystallinity of the polymer
was calculated as a function of temperature, within the two-phase model. In heating, the crystallinity decreased from 0.254
to zero in the temperature range from 220 to 360 K, confirming earlier DSC heat capacity measurements. During the stabilisation
periods, below325 K, negative drifts were observed, related to endothermic effects caused by melting. However, in the temperature
range from 325 K up to the end melting temperature, 360 K, positive drifts were measured, reflecting exothermic effects. These
are attributed to recrystallisation phenomena. The occurrence and amount of recrystallisation depend on the thermal history
of the sample: slower cooling and a longer time spent at a temperature of annealing clearly diminish recrystallisation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
