Suspension polymerization of styrene

Styrene-based polymer supports are produced by o/w suspension polymerization of styrene and divinylbenzene. Suspension polymerization is usually carried out by using a monomer-soluble initiator such as benzoperoxide (BPO) or 2,2-azo-bis-isobutylnitrile (AIBN) at a temperature of 55-85°C (19). A relatively high initiator concentration of 1-5% (w/w) based on the monomer is used. The time required for complete monomer conversion must be determined by preliminary experiments and is usually between 5 and 20 h, depending on the initiator concentration, the temperature, and the exact composition of the monomer mixture (11-18). 

Literature data for the suspension polymerization of styrene was selected for the analysi. The data, shown in Table I, Includes conversion, number and weight average molecular weights and initiator loadings (14). The empirical models selected to describe the rate and the instantaneous properties are summarized in Table II. In every case the models were shown to be adequate within the limits of the reported experimental error. The experimental and calculated Instantaneous values are summarized in Figures (1) and (2). The rate constant for the thermal decomposition of benzoyl peroxide was taken as In kd 36.68 137.48/RT kJ/(gmol) (11). 

The Instantaneous values for the initiator efficiencies and the rate constants associated with the suspension polymerization of styrene using benzoyl peroxide have been determined from explicit equations based on the instantaneous polymer properties. The explicit equations for the rate parameters have been derived based on accepted reaction schemes and the standard kinetic assumptions (SSH and LCA). The instantaneous polymer properties have been obtained from the cummulative experimental values by proposing empirical models for the instantaneous properties and then fitting them to the cummulative experimental values. This has circumvented some of the problems associated with differenciating experimental data. The results obtained show that ... 

In this process flame-retardants are fed in the extrusion process. EPS is obtained in a two-step process in the first step beads containing blowing agent are prepared by suspension polymerization of styrene in the second step the beads are expanded in the mold. In this case, flame-retardants are added during polymerization. 

Addition of Blowing Agents to Styrene Solutions of Polystyrene. If the pentane is added to a suspension polymerization of styrene after the bead identity point has been reached, the formation of blisters is avoided and the diffusion of pentane into the bead is rapid. Thus, the two objections to the pentane-in-monomer process and the post-polymerization impregnation processes are avoided (31, 119). The same system has also been used to introduce normally gaseous blowing agents, such as butane, propane, st/m-dichlorotetrafluoroethane, propylene, butene, and butadiene (51, 91,115). 

Villalobos, M. A., Hamielec, A. E., Wood, P. E., Bulk and suspension polymerization of styrene in presence of n-pentane an evaluation of monofunctional and bifunctional initiation, J. Appl. Polym. Sci. 50 (1993) 327. 

Apostilidou, C., Stamatousdis, M., On particle distribution in suspension polymerization of styrene, Collect. Czech. Chem. Commun. 55 (1990) 2244. 

Stamatousdis, M., Apostolidou, C., Characteristics of particle sizes produced by suspension polymerization of styrene, Part. Part. Syst. Charact., 9 (1992) 151. 

Tanaka, M., Oshima, E., Dispersing behavior of droplets in suspension polymerization of styrene in a loop reactor, Can. J. Chem. Eng. 66 (1988) 29. 

Schroder, R., Piotrowski, B., On particle formation during suspension polymerization of styrene, Ger. Chem. Eng. 5 (1982) 139. 

Masato, T., Hideyo, T., Isao, K., Natsakaze, S., Kazuhiko, H., Effect of stepwise and continuous reduction in impeller speed on particle size distributions in suspension polymerization of styrene, J. Chem. Eng. (Jpn.) 21 (1995) 118. 

Yang, B., Kamidate, Y., Takahashi, K., Takeishi, M., Unsteady stirring method used in suspension polymerization of styrene, J. Appl. Polym. Sci., 78 (2000) 1431. 

Vilchis, L., Rios, L., Guyot A., Guillot, J., Villalobos, M. A., In-situ formed copolymer of acrylic acid-styrene as stabilizer during suspension polymerization of styrene, DECHEMA Monogr. 134 (1998) 249. 

Olayo, R., Garcia, E., Garcia-Corichi, B., Sanchez-Vazquez, L., Alvarez, J., Poly (vinyl alcokol) as a stabilizer in the suspension polymerization of styrene the effect of the molecular weight, J. Appl. Polym. Sci. 67 (1998) 71. 

Table 15-6. Comparison of Bulk, Emulsion, and Suspension Polymerization of Styrene...

The controlled polymerization of p-methoxystyrene was also demonstrated in aqueous media using the /7-methoxystyrene HCl adduct as initiator and Yb(OTf)3 as Lewis acid activator [81]. Very recently, the aqueous living cationic suspension polymerization of styrene and methoxystyrene was reported by Ganachaud using the water adduct of p-methoxystyrene as initiator and B(CgF5)3 as water tolerant Lewis acid activator [82, 83]. 

Villalobos MA. Suspension polymerization of styrene through bifunctional initiators [M. Eng. Thesis]. Hamilton, Ontario Department of Chemical Engineering, McMaster University 1989. 

Polystyrene is made by bulk or suspension polymerization of styrene. Polystyrene is very low cost and is extensively used where price alone dictates. Its major characteristics [19,20] include rigidity, transparency, high refractive index, no taste, odor, or toxicity, good electrical insulation characteristics, low water absorption, and ease of coloring and processing. Polystyrene has excellent organic acid, alkali, salts, and lower alcohol resistance. It is, however, attacked by hydrocarbons, esters, ketones, and essential oils. 

The suspension polymerization of styrene is mostly carried out with dibenzoyl peroxide. Bulk polymerization is often no longer carried out purely thermally high-temperature initiators such as 1,2-dimethyl-1,2-diethyl-1,2-diphenyl ethane or vinyl silane triacetate, CH2=CH—Si(OOCCH3)3, are added. 

Polystyrene is made by bulk or suspension polymerization of styrene. It is commonly available in crystal, high impact, and expandable grades. Its major characteristics include transparency, ease of coloring and processing, and low cost. Styrene monomer is produced from benzene and ethylene. 

Mixed bmshes of hydrophobic and hydrophilic polymers grafted onto Au-NPs were also used as stabilizers for styrene droplets. Subsequent suspension polymerization of styrene led to PS particles with Au-NPs on their surface. Such raspberry particles might open new perspectives for superhydrophobic coatings with dual-size roughness. " ... 

Toy et al. [12] demonstrated that by replacing divinyl benzene with more flexible compounds usually increases their mechanical stability and allows them to absorb more solvent. In addition, when the cross-linked compounds contain oligomers of such materials as ethylene glycol, the compatibility with polar solvents increases. Subsequently, Janda and coworkers used polytetrahydrofuran in suspension polymerization of styrene to prepare general solid support resins for organic syntheses [13],... 

Villalobos, M.A., Hamielec, A.E., and Wood, P.E. (1993) Bulk and suspension polymerization of styrene in the presence of -pentane. An evaluation of monofimctional and bifimctional initiation.Polym. Sci., 50,327-343. 

Suspension polymerization of styrene, thermokinetic parameters for scale-up 432... 

Gel-Type Polystyrenes. Gel-type polystyrenes can be synthesized by radical suspension polymerization of styrene and DVB as reported in 1946 by Hohenstein and Mark (9,32). When suspended in a solvent with good swelling properties, these white soft beads assume a gelatinous state their volume may increase by 6-8 times and they become optically transparent. This process of swelling, as well as the shrinking, occurs from the outside to the inside of the polymer network and the increment of volume is in correlation with its solvation. This plays an important role in chemistry, because it is through such processes that the reactants diffuse into the polymer network where 99% of the functional sites reside (33). 

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