The mechanism by which p-benzoquinone retards the polymerization of methyl methacrylate has been studied using 14C-p-benzoquinone as retarder and W-azo-isobutyronitrile as initiator. Growing polymer radicals react with the quinone to give fairly unreactive radicals, most of which disappear by reaction with ordinary polymer radicals ; in this interaction combination occurs more frequently than disproportionation but the importance of the latter process increases with rising temperature. There is evidence that at 60" C some of the polymer-retarder radicals are able to attack monomer molecules, and as a result there is limited co-polymerization of methyl methacrylate and p-benzoquinone .

The effects of p-benzoquinone upon the sensitized copolymerization of styrene and methyl methacrylate a t 60°C. Lave been examined. Rates of polymerization were measured and the resulting copolymers were analyzed for combined quinone, by a tracer method involving 14C-labelled material, and for styrene by spectrophotometry. In its early stages, the copolymerization is quite strongly retarded but the rate gradually builds up as the quinone is consumed. The copolymer first formed is of low molecular weight and contains combined quinone, but as the reaction proceeds the average molecular weight of the polymer rises and the proportion of combined quinone falls. It is possible to account qualitatively for the differences between the effects of the quinone upon the copolymerization and the polymerizations of the separate monomers. ~ ZUSAMMENFASSUNG:Es wurde die Wirkung von p-Benzochinon auf die radikalische Copolymerisation von Styrol und Methacrylsauremethylester bei 60 "C untersucht. Die Polymerisationsgeschwindigkeiten wurden bestimmt und in den erhaltenen Copolymerisaten nach Verwendung von 14C-markierter Substanz das gebundene Chinon mittels der Isotopenmethode errechnet. Der Gehalt an Styrol wurde spektrophotometrisch ermittelt. Am Anfang wird die Copolymerisation durch das Chinon stark verzogert, doch steigt die Polymerisationsgeschwindigkeit in dem Mal3, in dem das Chinon verbraucht wird. Das anfangs gebildete Copolymerisat ist ziemlich niedermolekular und enthalt eingebautes Chinon, mit fortschreitender Reaktion steigt jedoch das Durchschnittsmolekulargewicht und die Menge an gebundenem Chinon wird geringer. Es ist moglich, die Unterschiede zwischen der Wirkung von Chinon a d die Copolymerisation und die Polymerisation der einzelnen Monomeren qualitativ zu errechnen.This paper contains the results of a preliminary study of the effects of p-benzoquinone upon the radical copolymerization of styrene and methyl

SynopsisThe monomer reactivity ratios for the copolymerization of tributyltin acrylate with styrene and allyl methacrylate have been found to be rl = 0.213, r2 = 1.910 and rl = 0.195, r2 = 2.257, respectively. Also, the copolymerization parameters of tributyltin methacrylate with styrene and allyl methacrylate were as follows: rl = 0.256, r2 = 1.104 and rl = 2.306, r2 = 1.013. Copolymerization reactions were carried out in solution at 7OoC using 1 mole % AIBN, and the copolymer compositions were determined by tin analysis. Ternary copolymerization of the three systems butyl methacrylate-tributyltin methacrylate-acrylonitrile, butyl acrylate-tributyltin methacrylate-acrylonitrile, and styrenetributyltin acrylate-acrylonitrile have been studied, and the terpolymer composition of each system was determined through tin and nitrogen analyses. The variation of instantaneous and average terpolymer composition with conversion fit satisfactorily the experimental results over a wide range of conversion.

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Several samples of casuarina and other sorts of wood were impregnated in methyl methacrylate (MMA) or its mixture with some other specific multifunctional monomers, such as ethylene glycol dimethacrylate (EGDMA), triethylene glycol dimethacrylate (TEGDMA), trimethylol propane trimethacrylate (TMPTMA) and tetrahydrofurfuryl methacrylate (THFMA). The monomer or mixture of monomers in the treated samples was polymerized either by being subjected to γ‐radiation from a60Co‐γ‐cell or by using 0.1 wt.‐% of benzoyl peroxide, or by employing both methods. The use of swelling agents was found to influence the gained monomer, polymer and the physical properties of the treated products, though the specific multifunctional monomer role has not yet clearly been identified, due to the variation in uniformity of distribution of wood constituents from one test piece to the other. 30kJ/kg were found to be the optimal dose for the highest compression strength. With 2000 and a 500 curie‐60Co sources, we found the same effect, and came to the conclusion that the dose rate was not important in the used ranges.