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The transition temperatures of poly(ethylene oxide) (PEO)/water systems were studied over the temperature range from −90 to 110°C by differential scanning calorimetry. The composition of the systems and the average molecular weight of the PEO were varied over a wide range. The systems under study tend to supercool and become partially or completely glassy depending on the cooling rate, composition, and PEO molecular weight. The glassy phases crystallize on being heated above their glass transition temperature. Systems containing about 60 wt % of PEO are most readily super cooled without crystallization. The dependence of melting temperatures and enthalpies on composition was studied and their isobar phase diagrams were drawn. They show that at a definite polymer content (about 50 wt %), which is molecular weight dependent, the systems behave as binary eutectic mixtures. The results confirm the idea that PEO forms quite stable molecular complexes with water.

Nascent polyethylene with high molecular mass (M" = f05, M , = LO6) produced in hydrocarbon medium in presence of TiCL/(C2Hs)2A1Cl/(C6Hs)2Mg catalyst was studied by means of X-ray diffraction, electron and light microscopy, and low-angle light scattering. It consists of porous spherulite-fibril aggregates indicating a not very high degree ofcrystallinity a (a = 0,5). Data, concerning the dependence ofspherulite dimensions, degree of crystallinity and other structure parameters of nascent polyethylene on polymerization time and temperature are discussed. Using the same structure-analytical methods some samples of nascent polyethylene were studied after annealing them in nitrogen atmosphere at different temperatures between 11&250°C with successive cooling to room temperature. Furthermore both the endo-and exothermal transitions occurring in the nascent and annealed structures after heating to 250 "C were studied by means of DTA and DSC. The experimental information leads to the conclusion that nascent polyethylene structures consist of crystalline folded chain lamellae with an increased amount of tie molecules between them as well as of extended chain crystals.

SYNOPSISThe aggregative stability of natural rubber ( N R ) latex stabilized by nonionic, fatty alcohol ethylene oxide condensate surfactant (Verol S-15) was studied in the presence of formic acid. Natural rubber latex having a n additional 3-5 phr surfactant is stable a t pH 2 when acidified by formic acid and can be successfully subjected to the subsequent in situ epoxidation. Using a large ratio of HzOz to isoprene unit (0.4-4.0 M / M ) and large excess of HzOz to HCOOH (3-13 M / M ) in reaction, the in situ epoxidation can be performed with reaction mixture having dry rubber content up to 35-37% at room temperature or up to 28% at 50°C. This reaction leads to products of large range of epoxide contents and characterized by absence of side-ring opening groups, proved by IR and 'H-NMR analysis. By infrared spectroscopy it was demonstrated a good correlation between the absorbances of the residual double bonds and of the epoxide groups versus the epoxide content in the range from 0 to approx. 60 mol % level. The solubility and gel content were studied in various solvents, demonstrating that epoxidation leads to increasing gel content at high epoxide levels and to enhancing sensitivity of the product toward polar solvents. By GPC, it was shown for the soluble fraction that epoxidation was accompanied by reducing the molecular weight and by change of the MWD compared with the original NR.