Polymerization Of Methyl Methacrylate In Presence Research Articles

Conducting Composites of Polymethylmethacrylate with Acetylene Black

ABSTRACT Conducting composites of polymethylmethacrylate and acetylene black were prepared via potassium chromate–sodium arsenite initiated redox polymerization of methylmethacrylate in presence of a suspension of acetylene black in aqueous methanol medium at 60°C. Prolonged extraction of the composite by tetrahydrofuran failed to extract the polymethylmethacrylate completely from the acetylene black surface, as confirmed by Fourier Transform Infrared studies. Scanning electron microscopic analyses revealed the formation of agglomerates of particles of nonuniform sizes and shapes. Thermal stability of the composite was appreciably improved relative to that for the unmodified base polymer. In sharp contrast to the d.c. conductivity of polymethylmethacrylate homopolymer (10−13 S/cm), the conductivity of the composites reached values between 10−4 S/cm to 10−2 S/cm corresponding to acetylene black loading of 7% to 25%.

Polymerization of methylmethacrylate in presence of maleic anhydride and amines

From analysis of the kinetics of polymerization it is concluded that in the system MMA-maleic anhydride-phenothiazine inhibition comes about through detachment of the labile H atom by the maleic anhydride radical from the phenothiazine molecule. In polar media the contribution of the chain regeneration reaction increases. On replacing phenothiazine by dimethylaniline the inhibitory effects do not show up while in presence of triethylamine the limiting stage of inhibition becomes the interaction of the MMA radicals with complex [triethylamine→maleic anhydride], triethylamine acting as a catalyst of the reaction of quadratic termination.

Aspects of the radical polymerization of methylmethacrylate in presence of heminal sulphides

The authors have studied the effect of the heminal sulphides containing two, three and four thioalkyl groups on the polymerization of methylmethacrylate. The presence of three active centres—the CS bond, the H atoms of the heminal carbon atom and the less active protons of the α-CH 2 groups of the alkyl residues—means that the transition from one sulphide to another changes the mechanisms of the influence of the sulphur compound on the polymerization process. On photo-initiation the course of photolytic rupture of the CS bond competes with the chain transfer reactions, which leads to a combination of inhibiting initiating properties.

Polymerization of methyl methacrylate by charge transfer mechanism by melamine and iron(III) complex

Methyl methacrylate (MMA) can be polymerized by the charge-transfer complex formed by the interaction of melamine (MM), MMA and carbon tetrachloride in a non-aqueous solvent like dimethyl sulphoxide (DMSO) or N- N-dimethylformamide. The polymerization can be accelerated by Lewis acids like Fe 3−. This paper reports the polymerization of MMA initiated by MM and CCl 4 and accelerated with hexakis dimethylsulphoxide iron(III) perchlorate [Fe(DMSO) 6] (ClO 4) 3. A, at 60°. Induction periods were observed for the polymerization initiated by MM and CCl 4 alone, but not when the molar ratio of MM to A became 3:1. The molecular weights of the polymers with 3:1 molar ratio of MM to A were higher than with MM alone. The rate constant for the polymerization of MMA in presence of [Fe(MM) 3] 3+ was 1.4181 × 10 −5 1 mol −1 sec −1 at 60°. The transfer constant for CCl 4, in the absence of A, is 4.66 × 10 −3.

Non-ideality in vinyl polymerization—VIII: Retarded polymerization of methyl methacrylate in presence of p-benzoquinone initiated by azobisisobutyronitrile

Detailed kinetic analysis of AIBN-initiated polymerization of methylmethacrylate in presence of p-benzoquinone has been reported. Primary radical transfer, whereby a primary radical transfers its radical reactivity to a transfer agent, has been considered along with macroradical transfer. It is found that the former process is quite appreciable in the system and must be allowed for to arrive at accurate values of transfer constants. Values of transfer constants for both primary radicals and macroradicals towards benzoquinone, and characteristic constants for degradative chain transfer and primary radical transfer have been evaluated applying the mathematical treatment developed previously. The mode of termination of macroradicals by fairly stable microradicals formed as a result of transfer has also been discussed.

Polymerization of methylmethacrylate in presence of tetramethylthiuramdisulphide

The effect of TMTD on the polymerization of methyl methacrylate was studied. The plot of R P vs [TMTD] 1 2 shows a maximum ascribed to participation of TMTD-radicals in cross (P′ + RS′) and mutual-termination (RS′ + RS′). The total polymerization rate is then well expressed by a derived relation. Study of the influence of TMTD on the molecular weight of polymethylmethacrylate allows characterization of the transfer process.

Polymerization of methyl methacrylate in the presence of the system tributyl aluminium-chromium acetylacetonate-2,2′-dipyridyl

Methyl methacrylate polymerization in presence of the system chromium acetyl-acetonate-triisobutyl aluminium takes place in accordance with a mechanism of anionic type. A means of activating the system with 2,2′-dipyridyl at −60° was discovered. With the activated system it was found that PMMA possessing higher stereo-specificity and enhanced thermal stability was obtainable in quantitative yields at room temperature. The general scheme is proposed for the reaction, and equations describing the kinetics of the process and changes in the molecular weight of the PMMA during polymerization have been derived. The rate constants obtained at 0° were (3.5 × 10 −4) for the reaction of chain transfer to monomer and (182 min −1) for the propagation reaction.

6-ナイロン繊維と水の存在下で重合したメタクリル酸メチルの重合物

6-ナイロン繊維と水の存在下で重合したメタクリル酸メチルの重合物