Polyethylene oxide crystallization

In experiments conducted to obtain controlled sizes of filler particles formed in a matrix, several polymers were used as the matrix. Copolymers were synthesized from polyethylene oxide (does not interact with CaCOs) and poly(methacrylic acid) (reacts with in situ crystallizing CaCOj). In the presence of polyethylene oxide, crystals grew to similar sizes as without any polymer. The presence of the poly(methacrylic acid) crystal size of CaCOa was reduced by a factor 5 to 10 depending on the concentration of the filler precursor. 

Strain-induced crystallization would presumably further improve the ultimate properties of a bimodal network. It would therefore obviously be of considerable importance to study the effect of chain length distribution on the ultimate properties of bimodal networks prepared from chains having melting points well above the very low value characteristic of PDMS. Studies of this type are being carried out on bimodal networks of polyethylene oxide) (55), poly(caprolactone) (55), and polyisobutylene (56). 

In the present work the limiting value of the linewidths for polyethylene oxide increases from 135 Hz in the melt above 70°C, to the range 300-350 Hz in the crystalline state at room temperature. As is indicated in Table I, the resonant linewidths for linear polyethylene increase substantially upon crystallization and attain values in the range 500-900 Hz at 45°C and 57.9 MHz. 

Research in this field is ongoing aiming to understand the mechanism of action of kinetic inhibitors. Lee and Englezos (2005) showed that inclusion of polyethylene oxide (PEO) to a kinetic inhibitor solution was found to enhance by an order of magnitude the performance of the hydrate inhibitor. Binding of inhibitor molecules to the surface of hydrate crystals was considered to be the key aspect of the mechanism of kinetic inhibition (Anderson et al.,... 

Although the motion of protons does not lead to electrical conduction in the case of benzoic acid, electronic and even ionic conductivity can be found in other molecular crystals. A well-studied example of ionic conduction is a film of polyethylene oxide (PEO) which forms complex structures if one adds alkaline halides (AX). Its ionic conductivity compares with that of normal inorganic ionic conductors (log [cr (Q cm)] -2.5). Other polymers with EO-units show a similar behavior when they are doped with salts. Lithium batteries have been built with this type of... 

Crystallization in asymmetric diblocks with compositions = 0.35 and 0.46 was also investigated by Hamley et al. (19966). It was found that a lamellar structure melted epitaxially (i.e. the domain spacing and orientation were maintained across the transition) to a hexagonal-packed cylinder structure in the /PE = 0.35 sample. This is illustrated in Fig. 5.15, which shows SAXS patterns in the solid and melt states, with a schematic of the epitaxial melting process (Hamley et al. 1996a.b). The same epitaxial transition has been observed for a polyethylene oxide)-poly(buty)ene oxide) diblock (Ryan et at. 1997) vide infra). 

Poly (ethylene oxide)/poly (butylene oxide) copolymers In polyethylene oxide)-poly(butylene oxide) (PEO-PBO) diblocks with short blocks, unfolded PEO blocks crystallize into lamellar crystals, and the PBO... 

While the presence of a filler affects the way a matrix crystallizes, the opposite is also true. In studies of in situ formation of calcium carbonate in different copolymers, different crystalline forms of calcium carbonate were found. Calcium carbonate crystallized without a polymer had a rhombohedral morphology. When crystallized in the presence of polyethylene oxide its morphology remained rhombohedral because the polymer does not interact with the crystal of calcium carbonate as it... 

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