A. Romanov

Monte-Carlo calculations of equilibrium partitioning of flexible chains into pores

Abstract The partition coefficient K of flexible coils distributed between bulk solution and a cubic pore was calculated by the Monte-Carlo method on a simple cubic lattice. Self-avoiding walks up to 100 steps have been generated with the variable intersegmental energy simulating coils in solvents of various thermodynamical quality. The coefficient K decreases rapidly from 1 in large pores to negligible values at λ over 0.8, where λ is the ratio of the characteristic dimensions of the coil and pore. The partition curve is only slightly affected by solvent quality. The marked change of coil statistics with solvent is observed in the region of large confinement of coils by pores for λ > 1. This does not seem to be properly reflected by the scaling theory. However, the local ‘conformational’ structure of chains is not influenced by pore constraints. Implications of results for the static and dynamic measurements of partition equilibrium and for transport properties of macromolecules in porous media are discussed.

Relationships between Tg and cohesive energy: 1. Dependence of Tg on the composition of copolymers

Abstract The possibility of expressing the glass transition temperature of copolymers and homopolymers with an n-alkyl side chain as a function of two parameters (cohesive energy and steric factor) is discussed. An empirical equation representing these two factors is proposed. Calculated values are in good agreement with literature data for the investigated systems.

Relationships between Tg and cohesive energy: 2. Prediction of Tg of homopolymers

Abstract An empirical equation expressing T g of polymers as a function of cohesive energy and steric factor is suggested so that the parameter V S in this equation may be considered to be an additive quantity. From the data on 44 polymers including 6 homologous series the increments of V S were calculated for individual structural units. The agreement of the calculated with the measured values of T g found for homopolymers and copolymers is discussed.

Dynamic mechanical properties of hybrids based on atactic polypropylene, polystyrene and polymethylmethacrylate

Abstract Dynamic mechanical characteristics of hybrid copolymers based on atactic polypropylene-polystyrene and atactic polypropylene-polymethylmethacrylate have been investigated by the method of torsional vibration at ca. 1 Hz. Atactic poly(propylene-block-styrene) and atactic poly(propylene-block-methylmethacrylate) have been prepared mechanochemically, atactic poly(propylene-grafted-styrene) from a solution by means of benzoyl peroxide. From the dynamic mechanical point of view all types behave as two-phase systems retaining the TG of the parent homopolymers.

Molecular motion in chlorinated ethylene-propylene copolymer

Abstract The molecular motion in solid chlorinated ethylene-propylene copolymer (EPc) (0–66 wt.% Cl) has been studied by the dynamical-mechanical method. It has been found that the damping maximum ascribed to the motion of groups from ue5f8(CH 2 ) 2 ue5f8 to ue5f8(CH 2 ) 4 ue5f8 shifts to higher temperatures with increasing chlorine content. The dependence of T g on the chlorine content has an exponential character. The mixtures of EPc pairs with a low content of chlorine show a limited compatibility but the copolymers are not compatible at the higher contents of chlorine.

Study of thermoelastic properties of ethylene-vinyl acetate copolymer

The thermoelastic properties of the random ethylene-vinyl acetate copolymer crosslinked with dicumyl peroxide were investigated. It was found that the relationships between equilibrium stress and temperature showed a discontinuity in the temperature range 38–42°C which was due to the crystalline character of the samples. The value of energetic contribution fu/f is negative at elongations ranging from 1.1 to 2.1 while it assumes a relatively high value at greater elongations. The values of relative energetic contribution fu/f change with elongation and are in agreement with the values of fu/f calculated from shear modulus for the region of medium elongations in the investigated range. The character of the relationship between fu or fu/f and elongation indicates that a change in the intra- and inter-molecular interaction energies occurs in the case of uniaxial strain of the investigated copolymer.