Styrene-polypropylene graft copolymers

Table V. Effect of Temperature on Sulfonation of Styrene-Polypropylene Graft Copolymers as Measured by Capacities of...

Vinyl pyridine-grafted polyolefins [229] having improved dyeability were prepared with >0.02 wt% based on the monomer of a perester catalyst and >0.1 wt% based on the monomer of a reducing agent promoter selected from lower-valent salts of multivalent metals, hydrosulfite, or alkali metal formaldehyde sulfoxylate. Thus, the polypropylene-styrene-vinylpyridine-graft copolymer prepared in the presence of 1 wt% sodium hydrosulfite and 0.5 wt% tert-huiyl 2-ethyl perhexanoate at 90 C was melt-spun into fibers... 

Polypropylene block and graft copolymers are efficient blend compatibilizers. These materials allow the formation of alloys, for example, isotactic polypropylene with styrene-acrylonitrile polymer or polyamides, by enhancing the dispersion of incompatible polymers and improving their interfacial adhesion. Polyolefinic materials of such types afford property synergisms such as improved stiffness combined with greater toughness. 

In addition, borane-containing POs can be prepared by copolymerization of olefin with borane monomers or by hydroboration of polyolefins including unsaturated groups, such as olefin-divinylbenzene copolymer and olefin-diene copolymers. Many kinds of graft copolymers, such as poly-elhylene-gra/f-poly( vinyl alcohol), PE-g-PMMA, polypropylcnc-gra/f-poly-(maleicanhydride-co-styrene), polypropylene-gra/f-poly(methacrylic acid), polypropylene-gra/f-poly(vinyl alcohol), polypropylene-gra/f-polycaprolac-tone (PP-g-PCL), polypropylcnc-gra/f-poly(methyl methacrylate) (PP-g-PMMA), poly( ethylene-co-propylene)-gra/f-poly(methyl methacrylate) (EPR-g-PMMA), and poly(ethylene-co-propylene)-gra/f-poly(maleic anhydride-costyrene), have been synthesized by such a method resulting in controllable composition and molecular microstructures [63-66]. 

There have been many studies of graft copolymer formation initiated by ionizing radiation, and methods have been discussed.88 Among the systems studied are styrene onto polyethylene,88 styrene onto polypropylene,100 styrene onto Nylon-6,101 styrene onto ethylene-vinyl acetate copolymers,102 styrene and MMA onto natural rubber,103 pentafluorostyrene onto Nylon and polyethylene,104 acrylamide onto Nylon-6,105 acrylamide onto starch,100 vinyl monomers... 

Finally, it could be mentioned here that the basic idea of hypercrosslinked network synthesis was also appfied to the preparation of porous fibrous sorbents. Liu et al. [278] have suggested grafting of styrene— DVB copolymer to the surface of polypropylene fibers, followed by the post-crosslinking of the grafted copolymer with 4,4 -bis-(chloromethyl)-diphenyl to 100% degree of crosshnking in a mixture of ethylene dichloride, nitrobenzene, and cyclohexane. After being coated with several successive layers of such hypercrosslinked polystyrene, the final fiber material... 

Unstable compounds such as peroxides and hydroperoxides are usual initiators for vinyl polymerization reactions. These groups can be introduced into a solid polymer by pre-irradiation in the presence of air or oxygen. Thermal decomposition of these groups in the presence of monomer yields graft copolymers. Some examples include grafting of acrylonitrile, styrene, and methyl methacrylate to polyethylene and polypropylene. 

Jia, D., Luo, Y., Li, Y., Lu, H., Fu, W, and Cheung, W. L. 2000. Synthesis and characterization of solid-phase graft copolymer of polypropylene with styrene and maleic anhydride. Journal of Applied Polymer Science 78 2482-2487. 

By using in-reactor grafting polymerization to produce a copolymer compatibilizer, such as polypropylene-graft-polystyrene (PP-g-PS) and the corresponding nonolefinic polymer component polystyrene (PS) simultaneously from the monomer styrene. This approach is used for the Hivalloy-PET system, discussed in the next section. 

Graft copolymers of a,j3-unsaturated carboxylic acids and anhydrides on a polypropylene backbone have often been used as compatibilizers for PP/PA blends. For example, a PP grafted with glycidyl and styrene moieties is a suitable compatibilizer (49). Likewise, a propylene homopolymer backbone is grafted with a st50-ene/meth-acrylic acid copolymer (PP-g-(S/MAA)) (50). 

PS = Polystyrene N6 = nylon 6 HOPE = high density polyethylene LDPE = low density polyethylene Nll= nylon 11 SAN = styrene acrylonitrile copolymer SMA = styrene-methaciylic acid copolymer MA-g-PP = maleic anhydride grafted polypropylene. 

The ESR technique has permitted to identify initial rupture points in mechanically degraded copolymers. Lazar and Szocs [53] investigated random, block, and graft copolymers of methylmethacrylate (MMA) and styrene (S). They found in a degraded mixture of equal parts MMA and S homopolymers equal concentrations of MMA and S radicals. In a random copolymer (MMA S = 1 1) the styrene radical prevailed clearly. By comparing the reactions of mechano-radicals in ball-milled PP with those of 7-radicals Kurokawa et al. [54] concluded that the mechano-radicals were produced and trapped on the fresh surfaces created by the breaking-up of solid polypropylene. 

The concept of PO macroinitiators centers on the introduction of an initiation moiety into an olefinic polymer chain for polymerization. The most effective route for preparing PO macroinitiators is by employing functional polyolefins containing hydroxyl groups or other reactive groups. These functional POs are prepared by copolymerization of olefins with functional monomers and post-polymerization reaction, as mentioned above. In the case where an initiation moiety was at the chain-end of the polyolefins, a block type copolymer is produced. It has been reported that thiol-terminated PP was used as polymeric chain transfer agent in styrene and styrene/acrylonitrile polymerization to form polypropylene-b/odc-polystyrene (PP-b-PS) and polypropylene-btock-poly(styrene-co-acrylonitrile) (PP-b-SAN) block copolymer [19]. On the other hand, polymer hybrids with block and graft structures can be produced if initiation moieties are in the polymer chain. 

Copolymers prepared by radiation grafting styrene in methanol to polypropylene powder. Sulfonation temperature, 90 C. 

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