B. Jasse

Fourier transform infra-red study of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide)-atactic polystyrene blends

Abstract Infra-red measurements of the dichroic ratio of absorption bands of atactic polystyrene-poly(2,6-dimethyl 1,4-phenylene oxide) blends provide a valuable method to investigate the orientation of the chains of both polymers. The results show that PPO and PS chains orient in a different way when subjected to an uniaxial strain, in spite of the compatible nature of the blend. The PPO orientational behaviour does not depend on PPO concentration in the studied concentration range (0–35%) while PS orientation regularly increases up to 25% PPO then remains constant.

Orientation and relaxation in uniaxially stretched poly(vinyl methyl ether)-atactic polystyrene blends

Abstract Infrared measurements of the dichroic ratio of polystyrene and poly(vinyl methyl ether) absorption bands allow us to determine chain orientation for each component in their compatible blends. Influence of strain rate and temperature of stretching on orientation of both polymer chains in blends containing up to 25% PVME has been studied. Mechanical relaxation master curves at a reference temperature T = T g +40°C have also been determined. Results are compared to previous results obtained in PS-PPO compatible blends. Although PPO and PVME chains behave differently PS chains behaviour is similar in the two types of blends and interpreted in terms of a hindrance of relaxation of PS chains induced by a modification of friction coefficients due to the molecular interactions which are at the origin of compatibility.

Orientation and relaxation in uniaxially stretched poly(methyl methacrylate)-poly(ethylene oxide) blends

Abstract Uniaxial orientation of poly(methyl methacrylate) (PMMA) and poly(ethylene oxide) (PEO) chains in their compatible blends has been measured using infra-red dichroism and birefringence. The influence of strain rate, temperature of stretching and PEO molecular weight on orientation of both polymer chains in blends containing up to 20% PEO has been studied. Mechanical relaxation master curves at a reference temperature T = T g + 50°C have also been determined. The results are interpreted in terms of a hindrance of relaxation of PMMA chains induced by a modification of friction coefficients due to the molecular interactions that are at the origin of compatibility.

Orientation and relaxation in uniaxially-stretched poly(2,6-dimethyl 1,4-phenylene oxide) ― atactic polystyrene blends

Abstract Infra-red measurements of the dichroic ratio of atactic polystyrene and poly(2,6-dimethyl 1,4-phenylene oxide) absorption bands provide a valuable method for the determination of orientation as well as relaxation of chains of both polymers during stretching of their compatible blends. Influence of strain rate, temperature of stretching, and molecular weight of the polymers on orientation of both polymer chains in blends containing up to 35% PPO has been studied. Orientation relaxation for both polymers has been analysed using Lodges constitutive equation. Master curves have been obtained for PPO and PS in the blends at a reference temperature T 0 = T g + 10°C. Results are interpreted in terms of an hindrance of relaxation of PS chains induced by interaction with a highly-oriented PPO network which slowly relaxes.

Evaluation of the birefringence of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide)-atactic polystyrene blends

Abstract The intrinsic birefringence of atactic polystyrene and poly(2,6-dimethyl 1,4-phenylene oxide) in their compatible blends are obtained from coupled birefringence and infra-red dichroism measurements. The experimental value obtained for poly(2-6-dimethyl 1,4-phenylene oxide) is in reasonable agreement with the value calculated from bond polarizabilities. These results allow evaluation of the angle between the normal to the benzene ring of polystyrene and the chain axis. This angle appears to be constant as a function of draw ratio and poly(2,6-dimethyl 1,4-phenylene oxide) percentage in the 0–35% studied range.

Orientation and relaxation in uniaxially stretched atactic polystyrene

Abstract Infra-red measurements of the dichroic ratio of atactic polystyrene absorption bands provide a valuable method of determination of orientation as well as relaxation of chains during stretching. Different strain rates and temperatures of stretching were used. Orientation relaxation was analysed using Lodges constitutive equation and a master curve was obtained at a reference temperature T 0 = 115°C. Orientation relaxation behaves similarly to mechanical relaxation and a scaling factor of 3.6 × 10 −8 m 2 N −1 holds between the two sets of results.

Orientation and relaxation in uniaxially stretched poly(o-chlorostyrene)-polystyrene blends

Abstract Orientation and relaxation of polymer chains have been analysed in uniaxially stretched films of poly( o -chlorostyrene) (PoCS) and of compatible PoCS/polystyrene (PS) blends. The intrinsic birefringence of PoCS is derived from fluorescence polarization and birefringence orientation measurements. Further, using Fourier transform infra-red spectroscopy, we have determined the angle between the dipole moment vector of some infra-red vibrations of PoCS and the chain axis. The orientation of the benzene ring with respect to the chain axis in oriented PoCS samples is identical to that observed in PS. In PoCS/PS blends, infra-red and birefringence measurements show that chain orientation of both polymers is almost the same and independent of the presence of the second component, in agreement with mechanical relaxation measurements. This result is in contrast with previous data on PS/poly(phenylene oxide) and PS/poly(vinyl methyl ether) blends. It corroborates well the assumption that change in friction coefficients is responsible for the orientation behaviour of compatible blends in which strong enough polymer-polymer interactions develop.

Influence of tacticity on orientation and relaxation in uniaxially stretched polymethylmethacrylates

Orientation and relaxation behavior in uniaxially stretched stereoregular polymethylmethacrylate (PMMA) was investigated. When compared at a reference temperature T = T g + constant, isotactic PMMA orients more readily and relaxes slightly faster than the conventional or syndiotactic polymers. Orientation relaxation of the different PMMAs can be reduced to a unique master curve, whatever the tacticity, when the results are compared at same monomeric friction coefficient.

Orientation and relaxation in uniaxially stretched poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) compatible blends

Abstract The orientation and relaxation of both polymer chains in compatible blends of poly(methyl methacrylate)-poly(styrene- co -acrylonitrile) (PMMA-SAN) have been studied using Fourier transform infra-red spectroscopy. The influence of strain rate and stretching temperature on orientation have been measured. In these blends, where inter-chain interactions are almost nonexistent, both polymers orient differently over the whole concentration range, with the PMMA chains being always more oriented than the SAN chains. Orientation relaxation master curves have also been established. A change in molecular weight between entanglements does not seem to be the main factor influencing orientation and relaxation, but use of the monomeric friction coefficient, which reflects local mobility and interactions, as a scaling factor allows one to obtain two general master curves which are representative of the overall behaviour of the PMMA and SAN chains in their compatible blends.

Fourier-transform infra-red and birefringence studies of orientation in uniaxially stretched poly(methyl methacrylate)-poly(trifluoroethylene) blends

Abstract Orientation of both polymer chains in compatible blends of poly(methyl methacrylate)-poly(trifluoroethylene) (PMMA-PF 3 E) has been studied using Fourier-transform infra-red and birefringence measurements. Two different behaviours are observed depending whether or not PF 3 E crystallizes. In the concentration range where the material remains homogeneous, i.e. up to 10% of PF 3 E, one observes an increase of PMMA orientation with respect to the pure polymer, at the same drawing temperature T − T g . In this domain, PF 3 E orientation is insensitive to the concentration of this polymer in the blend. When PF 3 E crystallizes, a small amount of PF 3 E (∼3%) remains in the PMMA amorphous phase. Thus, the orientation of PMMA is insensitive to the original PF 3 E concentration and remains higher than the orientation observed in pure PMMA under the same experimental conditions ( T − T g = constant). The orientation of the semicrystalline PF 3 E phase increases with crystallinity but remains insensitive to the stretching temperature. The orientation behaviour is well explained by a change of the friction coefficient and by the existence of a physical network originating from the presence of crystallites in crystallized blends.