Methyl methacrylate thermal

Rogalewicz, Voelkel [32] Poly(methyl methacrylate) thermal degradation Methyl methacrylate, additives PDMS... 

With methyl methacrylate, thermal self-polymerization also occurs, but with a rate about two orders of magnitude smaller than with styrene. 

Optics. Good optical properties and low thermal resistance make poly(methyl methacrylate) polymers well suited for use as plastic optical fibers. The manufacturing methods and optical properties of the fibers have been reviewed (124) (see Fiber optics). Methods for the preparation of Fresnel lenses and a Fresnel lens film have been reported (125,126). Compositions and methods for the industrial production of cast plastic eyeglass lenses are available (127). 

Monomers such as methyl methacrylate [80-62-6] are often used in combination with styrene to modify refractive index and improve uv resistance. Vinyltoluene [25013-15-4] and diaHyl phthalate [131-17-9] are employed as monomers in selective mol ding compositions for thermal improvements. 

An example of this improvement in toughness can be demonstrated by the addition of Vamac B-124, an ethylene/methyl acrylate copolymer from DuPont, to ethyl cyanoacrylate [24-26]. Three model instant adhesive formulations, a control without any polymeric additive (A), a formulation with poly(methyl methacrylate) (PMMA) (B), and a formulation with Vamac B-124 (C), are shown in Table 4. The formulation with PMMA, a thermoplastic which is added to modify viscosity, was included to determine if the addition of any polymer, not only rubbers, could improve the toughness properties of an alkyl cyanoacrylate instant adhesive. To demonstrate an improvement in toughness, the three formulations were tested for impact strength, 180° peel strength, and lapshear adhesive strength on steel specimens, before and after thermal exposure at 121°C. 

The reaction of ACPC with linear aliphatic amines has been investigated in a number of Ueda s papers [17,35,36]. Thus, ACPC was used for a interfacia] polycondensation with hexamethylene diamine at room temperature [17] yielding poly(amide)s. The polymeric material formed carried one azo group per repeating unit and exhibited a high thermal reactivity. By addition of styrene and methyl methacrylate to the MAI and heating, the respective block copolymers were formed. 

The thermally-initiated styrene system is considerably simpler than most industrial applications. Though these experiments provided useful guidelines, it was difficult to develop broadly applicable design criteria without carefully evaluating a broad range of monomer, polymer and initiator systems. Hence we extended our kinetic model to some other monomer systems such as styrene and methyl methacrylate using common initiators such as benzoyl peroxide (BPO) and... 

Researchers at AECI s Research and development Department have developed a novel microwave depolymerisation process for the thermal decomposition of polymethyl methacrylate and the recovery of the monomer methyl methacrylate. This comprehensive article supplies a detailed explanation and examination of the process which has been patented in South Afriea. The microwave technology provides a purer produet which will simplify downstream processing and reduee effluent volume and chemical consumption. 

Results for styrene - yield Ea 21 kcal. Since Ep — Et/2 was found previously to be 6.5 kcal., we conclude that the activation energy Ei for thermal initiation in styrene is 29 kcal., which would be quite acceptable for the process (21), already rejected on other grounds. For methyl methacrylate, Ea—l kcal. and Ep — Et/2 = b kcal. Hence Ei = 22 kcal. These initiation reactions are very much slower than is normal for other reactions with similar activation energies. The extraordinarily low frequency factors Ai apparently are responsible. For methyl methacrylate, Ai is less than unity. Interpreted as a bimo-lecular process, this would imply initiation at only one collision in about 10 of those occurring with the requisite energy ... 

In thermal polymerization where the rate of initiation may also vary with composition, an abnormal cross initiation rate may introduce a further contribution to nonadditive behavior. The only system investigated quantitatively is styrene-methyl methacrylate, rates of thermal copolymerization of which were measured by Walling. The rate ratios appearing in Eq. (26) are known for this system from studies on the individual monomers, from copolymer composition studies, and from the copolymerization rate at fixed initiation rate. Hence a single measurement of the thermal copolymerization rate yields a value for Ri. Knowing hm and ki22 from the thermal initiation rates for either monomer alone (Chap. IV), the bimolecular cross initiation rate constant kii2 may be calculated. At 60°C it was found to be 2.8 times that... 

Biesenberg, J. S. etal., J. Polym. Eng. Sci., 1976,16, 101-116 Polymerisation of methyl methacrylate initiated by oxygen or peroxides proceeds with a steady increase in velocity during a variable induction period, at the end of which a violent 90°C exotherm occurs. This was attributed to an increase in chain branching, and not to a decrease in heat transfer arising from the increasing viscosity [ 1 ]. The parameters were determined in a batch reactor for thermal runaway polymerisation of methyl methacrylate, initiated by azoisobutyronitrile, dibenzoyl peroxide or di-ferf-butyl peroxide [2],... 

A detailed understanding of the course of a reaction between a polymer and an additive will permit one to use that information to design new flame retardants. The reaction between poly(methyl methacrylate), PMMA, and red phosphorus is described and that information used to determine that CIRh(PPh3)3 should be used as a flame retardant. The results of this investigation are then used to choose the next additive. A recurring theme is the efficacy of cross-linking as a means to impart an increased thermal stability. 

In this paper we describe the reaction of poly(methyl methacrylate), PMMA, and red phosphorus and use that information to predict that the reaction of Wilkinson s catalyst, CIRh(PPh3)3, and PMMA may be a worthwhile investigation. Finally information from this reaction is utilized to identify other potential additives and the reaction of these cobalt compounds with PMMA is described. Part of the strategy that will be explored is a strategy of cross-linking to produce materials with greatly increased thermal stability. 

Feliu, J. A., C. Sottile, C. Bassani, J. Ligthart, and G. Maschio (1996). "Thermal Characterization of the Polymerization of Methyl Methacrylate." Chemical Engineering Science 51, 11,2793-98. 

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