Methyl Methacrylate Mixtures Research Articles

Infrared studies of stereoregular polymerization of methyl methacrylate and methacrylonitrile by organometallic compounds

AbstractInfrared spectra of reaction mixtures of methyl methacrylate or methacrylonitrile with an equimolar amount of organometallic compounds were investigated in relation to the stereoregulating ability of the catalysts in polymerization. It was found that the carbonyl or nitrile stretching frequency correlated with the stereoregularity of polymers prepared with the corresponding catalysts; i.e., the higher the frequency, the higher the isotacticity. From these results a mechanism of isotactic polymer formation was proposed, in which catalyst counterion was located near the carbonyl group in polymer terminal and that of monomer to be reacted, and consequently the isotactic polymerization is facilitated.

Polymerization of styrene–methyl methacrylate mixtures initiated by butyllithium

Polymerization of styrene–methyl methacrylate mixtures initiated by butyllithium

The fine structure of cotton fibre as revealed by swelling during methacrylate embedding

Water-swollen cotton fibres, accommodated to the embedding medium by means of a solvent exchange technique, were embedded in a mixture of methyl methacrylate and n-butyl methacrylate and sectioned with a diamond knife. Examination of the sections under the electron microscope showed that the swelling effect of the water on the fibres was subsequently enhanced by an enormous additional swelling that occurred during the polymerization of the embedding medium. This additional swelling is explained by the assumption that the polymerization reaction proceeds in the medium permeating the fibre at a faster rate than in the external medium. In consequence, monomer diffuses from outside into the fibre. Since the methacrylate embedding technique can disperse the cellulose to a great extent, it provides a suitable method for studying the structure of the cotton fibre.

Synthesis of graft copolymers by a transesterification method

AbstractIt is shown for the first time that mutual transesterification between carbochain polyesters (polymethyl methacrylate) and heterochain polyesters may be used for synthesizing graft copolymers. The graft copolymers obtained from polymethyl methacrylate and crystalline polyesters are crystalline have high softening temperatures. The grafting of amorphous polyesters yields amorphous graft copolymers. An increase in the number of graft side chains is accompanied by a decrease in intrinsic viscosity of the copolymer and by a rise in value of the Huggins constant. The decrease in the intrinsic viscosity is not the result of a degradation process, since polymethyl methacrylate may be regenerated by methanolysis of the graft copolymers. The intrinsic viscosity of the regenerated polymethyl methacrylate is equal to that of the initial polymer. Graft copolymers from polymethyl methacrylate and heterochain polyesters possess a lower tensile strength and higher ultimate elongation than polymethyl methacrylate. It was also established that on heating mixtures of methyl methacrylate and ω‐hydroxyacids in the presence of a catalyst graft copolymers form by simultaneous polymerization, polycondensation, and mutual transesterification reactions. Some correlations in this process and the properties of the resultant graft copolymers have been studied.

Ultrasonic Absorption of Polymer Solutions

IT is well known that the presence of a small amount of low-absorption solute in a highly absorbing solvent will reduce the absorption of the solution by much more than would be expected from simple proportionality. This is the case for mixtures of benzene (high absorption) with methyl methacrylate (low absorption). Wada and Shimbo1 have shown that if polymethylmethacrylate is added to a benzene–methylmethacrylate mixture the resultant absorption is higher than in the absence of the polymer, although remaining less than that for the pure benzene. They suggested that this rise in absorption is caused by some of the monomer becoming ‘enclosed’ within the polymer chains so that it is no longer effective in reducing the solution's absorption. It is possible, however, to account for this rise in absorption without assuming ‘enclosure’.

Polymerization of methacrylate induced by gamma irradiated polymethyl methyacrylate

A transparent gel was produced in two weeks time from a mixture of methyl methacrylate and polymethyl methacrylate which had been irradiated for 24 hours using a 5000 curie Co/sup 60/ source. (C.J.G.)

Reactivity of monomers in copolymerization

AbstractAn investigation of the copolymerization of many monomer pairs induced by benzoyl peroxide has shown that an order of monomer reactivity with radicals exists. By utilizing the data available, it was possible to make a semiquantitative arrangement of many monomers according to their relative rates of reaction with radicals. A symmetrical selectivity factor is assumed to account for deviations from the order in copolymerization reactions. This selectivity may be attributed to (1) complex formation between monomers or to (2) dipole, steric, or other factors which are independent of concentration. Copolymerization equations have been derived for each case and application of them to styrene–methyl methacrylate mixtures has indicated that selectivity due to (2) is most important in this system. The equation for case (2) has been applied to other copolymer systems.