Benzoyl peroxide, as initiator

In studies of the polymerization kinetics of triaUyl citrate [6299-73-6] the cyclization constant was found to be intermediate between that of diaUyl succinate and DAP (86). Copolymerization reactivity ratios with vinyl monomers have been reported (87). At 60°C with benzoyl peroxide as initiator, triaUyl citrate retards polymerization of styrene, acrylonitrile, vinyl choloride, and vinyl acetate. Properties of polyfunctional aUyl esters are given in Table 7 some of these esters have sharp odors and cause skin irritation. 

Fig. 1. Bulk polymerization of vinyHdene chloride at 45°C, with 0.5 wt % benzoyl peroxide as initiator (29).

Eor bulk copolymerization of methyl, octyl, dodecyl, and octadecyl vinyl ethers using benzoyl peroxide as initiators at 40—100°C with the following comonomers (M, ), where is 0 in all cases (6), the values of are... 

Polymer Preparation. Polymers were typically prepared in ethyl acetate solution at reflux temperature using benzoyl peroxide as initiator. They were isolated by two precipitations from ethyl acetate solution into methanol and were dried under vacuum. Molecular parameters of the polymers prepared are listed in Table II. Materials ... 

We conceived that, if the alcohol was to be deoxygenated to a radical, an olefinic linkage would be formed by -elimination of a phenylsulfonyl radical. The xanthate function is a convenient radical source and gave the olefin in about 80% yield in toluene under reflux using AIBN or benzoyl peroxide as initiators and Ph2SiH2.22... 

We have prepared polymethacrylic anhydride by polymerization at 100° in toluene solution with benzoyl peroxide as initiator and at... 

The styrene copolymers were prepared by bulk polymerization at 100°, using benzoyl peroxide as initiator. Methyl methacrylate styrene mole ratios in the feed were 10 90, 25 75, 50 50, 75 25, and 90 10. Conversions varied from 4.5 to 8.1%. Methyl methacrylate a-methyl-styrene copolymers were prepared using benzoyl peroxide at lower a-methylstyrene ratios and U.V. or Co60 gamma radiation to initiate copolymerization at the highest a-methylstyrene ratios, in which reaction is very slow. The mole ratios in the monomer feed were 12 88, 28 72, 54 46, 78 22, and 91.5 8.5. 

To check whether vinyl esters of strongly branched acids behave differently, mixtures of vinyl acetate and VV 911 in molar ratios of 1/3, 1/1, and 3/1 were polymerized in bulk to a conversion of about 10%, using benzoyl peroxide as initiator at 50°C. The reaction mixtures were then diluted with benzene, and the polymers were precipitated with methanol. After five further dissolutions in benzene and precipitation with methanol the polymers were freeze dried from their solutions in benzene and analyzed for carbon content. The results given in Figure 1 show that, at least for practical purposes, the assumption that r1 = r2 = 1 is valid, and at any time during the polymerization random copolymers are formed at any vinyl acetate-VV 911 ratio. 

Other examples of peroxy inisurfs can also be found in Russian scientific papers. As for instance in Ref. [41] Voronov et al. describe a polymeric surfactant with peroxy side chains for application as inisurfs in emulsion polymerization. They obtained the polymeric inisurf (Inisurf 2) by copolymerization of a peroxide containing monomer (dimethyl-vinylethinyl-methyl-tm-butyl-peroxide) with acrylic or methacrylic acid or 2-methyl-5-vinyl pyridine with benzoyl peroxide as initiator in the presence of dodecylmercaptan as chain transfer agent. The resulting copolymers are water soluble at appropriate pH-values, surface active, and exhibit a critical micelle concentratioiL... 

The bulk polymerization of DAP has been studied at 60°C with azobisisobutyronittile as initiator (39). Branching of the polymer chains is confirmed by enhanced broadening of the molecular weight distribution imtil gdation occurred at about 25% conversion. In copolymerizations with styrene at 80°C with benzoyl peroxide as initiator the gel time increases with fraction comonomer in the feed. Both the yidd of gd and the styrene units in the gel increase with copolymerization time. Heating DAP prepolymer with styrene in benzene solution at 60—100°C with the initiators gives no gelation, but slow formation of polystyrene and copolymer. 

We have shown that commercial CR-39 monomer samples can be purified by column chromatography. Polymerization with benzoyl peroxide as Initiator gives highly crossllnked polycarbonate samples suitable for use as high energy radiation dosimeters. A method has been developed to characterize the polymer and to count radiation tracts with a computer controlled Quantlmet Image analyzer. 

The bulk polymerization of allyl acrylate with benzoyl peroxide as initiator to 10% conversion gave a brittle, glassy polymer which was considered partially cyclized with a Kc (ratio of rate of cyclization to the rate of bimolecular propagation, cf., Table IV) of 0.41 moles/liter [72]. The polymer was described as soluble in both toluene and in carbon tetrachloride. 

Procedure 6-1 is an example of the solution polymerization of allyl methacrylate using benzoyl peroxide as initiator. The polymer is said to be thermoplastic. 

Example 7.2 The data for the bulk polymerization of styrene at 60°C with benzoyl peroxide as initiator are... 

Since the initiator concentration remains fairly unchanged in the course of vinyl polymerization, if the initiator efficiency is independent of monomer concentration, first-order kinetics with respect to the monomer is expected. This is indeed observed over a wide extent of reaction for the polymerization of styrene in toluene solution with benzoyl peroxide as initiator (Figure 7.3). The polymerization of certain monomers, either undiluted or in concentrated solution, shows a marked deviation Irom such first-order kinetics. At a certain stage in the polymerization process, there is a considerable increase in both the reaction rate and the molecular weight. This observation is referred to as autoacceleration or gel effect and is illustrated in Figure 7.4 for polymerization of methyl methacrylate at various concentrations of the monomer in benzene. 

Metallocene mono- and dimethacrylates are fairly polymerizable (80 °C, DMFA, 0.3-0.5% benzoyl peroxide as initiator) to give the polymers 93 and 94 [72]. 

Figure 1.1 Curves of per cent conversion against time for polymerization of methyl methacrylate at 50 °C using benzoyl peroxide as initiator and benzene as diluent. The initial monomer concentrations, [MMA]q, are given as percentages of the bulk monomer concentration. Autoacceleration is evident in the curves with [MMA]o of 100%, 80% and 60%. (Adapted from ref. 7)...

Ohtani, H., Tanaka, M., and Tsuge, S., Pyrol3 is-Gas Chromatographic Study of End Groups in Poly(methyl methacrylate) Radically Polymerized in Toluene Solution with Benzoyl Peroxide as Initiator, J. Anal Appl Pyrolysis, 15,167,1989. 

One other application of such monoliths, for the S5mthesis of a split and mix library, was presented by Janda (115). The preparation of euclidean-shape monoliths was performed using a monomer mixture of styrene, chlroromethylstyrene, and 1,4- bis(vinylphenoxy)butane as cross-linker. Dodecanol was used as inert diluent and benzoyl peroxide as initiator. 

TVEX synthesis is carried out in an agitated water-jacket reactor [4,5]. Once the reactor is loaded with a 0.5% starch solution as an emulsion stabilizer, the reaction mixture containing styrene, divinylbenzene (cross-linking agent), the extractant, and benzoyl peroxide as initiator of radical copolymerization is fed into the reactor at 50°C. After 8 honrs of polymerization, TVEX granules are obtained and then are washed with water and size classified. 

Butanediamine (BDA)-g-PDLLA was synthesized by grafting maleic anhydride onto the side chains of PDLLA via melt-free radical polymerization using benzoyl peroxide as initiator. BDA was then grafted via a V-acylation reaction. The biodegradation behavior of these graft copolymers could... 

Modelling of the Free Radical Polymerization of Styrene with Benzoyl Peroxide as Initiator... 

The expressions for the kinetic rate constants and the value for initiator efficiency, /, that are appropriate for styrene polymerization with benzoyl peroxide as initiator have been taken from the literature (Biesenberger and Sebastian 1983), (Berger and Meyerhoff 1989), (Buback 1995), (Moad and Solomon 1995). 

The proposed model was then validated with data obtained from a laboratory batch polymerization reactor (Boodhoo 1999). The polymerization system consisted of styrene as monomer in an initial concentration of 7.28 mol/dm, benzoyl peroxide as initiator in an initial concentration of 5.1 10 mol/dm and toluene as solvent in an initial concentration of 1.567 mol/dm. Batch temperature was set at 90°C and agitation speed was 500 rpm. The model results in the case of termination only by coupling, and termination only by disproportion, are compared with experimental results. The results are presented in Figs. 1,2,3 and 4. 

The use of azobisisobutyrylonitrile and benzoyl peroxide as initiators for the grafting of vinyl acetate on to cellulose has been compared. The chain-transfer mechanism occurring in these systems has been verified by carrying out grafting experiments in the presence of the chain-transfer agent propane-1-thiol. 

Poly(styrene-co-NVK) copolymers and NVK-homopolymers with controlled molecular weight and narrow polydispersities can be synthesized by N-oxyl-controlled free radical copolymerization using benzoyl peroxide as initiator and 2,2,6,6-Otetramethyl-piperidine-N-oxyl as terminating agent. The copolymerization behaves in a living fashion and allows the synthesis of blockcopolymers [426,427]. 

The polymerization of vinyl fluoride has been reported to be difficult but the polymer was introduced commercially in film form in about 1960. Details of the polymerization techniques used have not been disclosed. The polymer may be obtained by polymerization of vinyl fluoride in the presence of water, using benzoyl peroxide as initiator at 80°C and pressures up to 1000 atmospheres. 

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