Grafting of styrene

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

Miscellaneous Copolymers. VP has been employed as a termonomer with various acryUc monomer—monomer combinations, especially to afford resins usehil as hair fixatives. Because of major differences in reactivity, VP can be copolymerized with alpha-olefins, but the products are actually PVP grafted with olefin or olefin oligomers (151,152). Likewise styrene can be polymerized in the presence of PVP and the resulting dispersion is unusually stable, suggesting that this added resistance to separation is caused by some grafting of styrene onto PVP (153). The Hterature contains innumerable references to other copolymers but at present (ca 1997), those reviewed in this article are the only ones known to have commercial significance. 

Compaction of cellulose acetate desalination membranes, causing reduction in throughput and performance with time, can be significantly reduced by irrigation grafting of styrene onto the membrane (145). 

The mechanistic details of photo-induced grafting of styrene onto cellulose in the presence of mineral acids with methanol and dioxane as solvents was investigated... 

Applications of radiation grafting in the coating industry for improving adhesion and other properties has been an active field. For instance, grafting of styrene onto polyester fibers was found to improve the interfa-cial adhesion between grafted chopped polyester fibers and polystyrene used as a matrix [139]. 

Cross-linked polystyrene and its functional derivatives are widely used in organic syntheses as polymeric reagents and catalysts.28 However, thermal and chemical stability of such materials has to be better. Some improvement in these properties can be achieved by the grafting of styrene with the following chemical modification or grafting of other functional monomers. 

Grafting of functional monomers onto fluoropolymers produced a wide variety of permselective membranes. Grafting of styrene (with the following sulfonation), (meth)acrylic acids, 4-vinylpyridine, A-vinylpyrrolidone onto PTFE films gave membranes for reverse omosis,32-34 ion-exchange membrane,35-39 membranes for separating water from organic solvents by pervaporation,49-42 as well as other kinds of valuable membranes. 

Figure 1. Role of dose rate in the synergistic effect of divinyl-benzene and sulfuric acid on grafting of styrene on polypropylene film in methanol dose rate of 4.1 x 104rad/hr to total dose of 2.4 x lO rad (A) styrene-methanol, (o) styrene-sulfuric acid (0.2M). ( ) styrene-methanol-divinylbenzene (1% v/v), and (o) styrene-methanol -di vinyl benzene (1% v/v)-sulfuric acid (0.2M). dose...

Table III. Comparison of Acid with Inorganic Salts and Urea as Additives in Grafting of Styrene to the Polyolefins Initiated by Ionising Radiation3...

Consistent with the preceeding acid work, when TMPTA is added to the monomer solutions containing either lithium salt or urea, synergistic effects are observed for the radiation grafting of styrene to polypropylene (Table IV). Again the maximum increase in yield occurs in the monomer solution corresponding to the Trommsdorff peak. 

As the time of exposure to UV is increased, the magnitude of the synergistic effect between TMPTA and lithium nitrate is increased dramatically for the UV grafting of styrene to polypropylene (Table XI) such that after 16 hours of irradiation very large yields are obtained. Even with TFMA, the grafting yield in the 30% monomer solution is increased by almost one order of magnitude due to the synergistic effect. 

Table XII. Effect of Organic Additives (Urea, Silanes, Fluorinated Alkyl esters) on Grafting of Styrene to Polypropylene Initiated by UVa...

A theory for this acid effect has been developed essentially from the wool and cellulose work (3,4). Recently, in a brief communication, we reported analogous acid enhancement effects in the radiation grafting of monomers such as styrene in methanol to nonpolar synthetic backbone polymers like polypropylene and polyethylene (5). In the present work, detailed studies of this acid enhancement effect are discussed for the radiation grafting of styrene in various solvents to polyethylene. The results are fundamentally important since most of the experiments reported here have been performed in solvents such as the low molecular weight alcohols which, unlike cellulose and wool systems, do not swell polyethylene. 

TABLE IV. Effect of Acid Structure in Methanol to Polyethylene.a Grafting of Styrene in ... 

TABLE V. Effect of Acid on Homopolymer Formation in the Radiation Grafting of Styrene in Methanol to Polyethylene.0... 

Figure 1. Grafting of styrene in methanol to polyethylene at various dose rates total dose 0.2 X 10 rads. (V) 0.117 X 10s rad/hr, without HsSOk (Y) with 0.1 N H S04 (0)0.196 X 10s rad/hr, without HsSOi (9) with 0.1N H2SOi ( ) 0.279 X 106 rad/hr, without ( ) with 0.1N ffsS04 ( ) 0.546 X 10 rad/hr,...

TABLE VII. Effect of Dose Rate in the Presence of Acid on the Grafting of Styrene in DMF to Polyethylene. 

TABLE VIII. Effect of Acid in Methanol to in the Radiation Grafting of Styrene Polyethylene using Open Tubes.a ... 

The parameters which predominantly influence the acid effect in radiation grafting of styrene monomer to polyethylene film are the structure of solvent, the concentration of monomer and the dose rate. Because these three variables are inter-related, it is difficult to predict, a priori, the conditions required to yield an optimum in grafting. In this respect the type of solvent used is particularly important. 

Figure 2. Grafting of styrene in DMF to polyethylene in the presence of HtSOt at various concentrations total dose 0.5 X 10s rad at dose rate 0.080 X 10s rad/hr...

Both Odian and Silverman models satisfactorily explain most of the observed results in all solvents (Tables I-III, VI) used in the present study, however there are some exceptions especially when solvents other than the alcohols are used (Table VI). Thus the Odian mechanism is not consistent with the DMF data nor can the Silverman model account for the acetone results. In addition, in further preliminary studies with grafting of styrene to polyethylene (10) in solvents other than those reported here both Odian and Silverman mechanisms are deficient. The problem is that possible contributions from the radiation chemistry of the components in the grafting reaction need to be considered in formulating a complete mechanism for the overall process. 

Acid enhancement in the radiation grafting of styrene in methanol to cellulose (4), wool (3) and in preliminary work with the polyolefins (5 6) has been proposed as being predominantly due to such reactions. 

Rager, T. 2003. Pre-irradiation grafting of styrene/divinylbenzene onto poly(tetrafluoroethylene-co-hexafluoropropylene) from non-solvents. Helvetica Chimica Acta 86 1966-1981. 

Phadnis, S., Patri, M., Chandrasekhar, L. and Deb, P. C. 2005. Proton-exchange membranes via the grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer by a preirradiation technique. III. Thermal and mechanical properties of the membranes and their sulfonated derivatives. Journal of Applied Polymer Science 97 1418-1425. 

Rouilly, M. V., Koetz, E. R., Haas, O., Scherer, G. G. and Chapiro, A. 1993. Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto Teflon-EEP films Synthesis and characterization. Journal of Membrane Science 81 89-95. 

Initiators such as BPO are used not only for the initiation of chain reaction polymerization, but also for the curing of polyesters and ethylene-propylene copolymers, and for the grafting of styrene on elastomeric polymer chains. 

Grafting of styrene (ST) onto polybutadiene (PB) can occur in two ways Via a chain-transfer reaction with an allylic hydrogen of the 1,4- and the 1,2-units (Case 1) via copolymerization with C=C-double bounds of polybutadiene, in particular with the vinyl groups of the 1,2-units (Case 2) ... 

The reactions leading to the formation of cross-links between polymeric chains also can be employed to attach various compounds to the polymeric backbone. Using this technique, grafting of styrene, mercaptans, carbon tetrachloride, and other compounds can be carried out. 

Effect of Solvents on Radiation Grafting of Styrene to Polypropylene ... 

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