Graft polyolefins styrene

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

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. 

The second growing trend is the impact modification of polyolefin blends using styrenic block copolymers, which are known to be clear, strong, have low glass transition, compatible with PP, form interpenetrating polymer networks, and very efficient in contrast to maleic anhydride-grafted polyolefins. 

A number of other companies are also marketing or developing com-patibilizing additives. For example, Dexco Polymers, of Houston, Tex., sells a line of styrenic block copolymers which can enhance properties of mixed streams of polyolefins. BASF is developing compatibilizers for mixtures of polystyrene with polyethylene or polypropylene and for mixtures of ABS with polypropylene. DuPont sells compatibilizers based on maleic anhydride-grafted polyolefins for compatibilization of mixed polyolefins. ... 

Dow has prepared a compatibilized blend of PC and linear PE. The compati-bilizer used was EPDM grafted with SAN. The product has high impact strength and good melt processability. Polymer alloys with S-AMS copolymer and PP with styrene-grafted polyolefin copolymer have been reported. Triax 1000 of Monsanto is a blend of nylon and ABS compatibilized with styrene-acrylonitrile and glycidyl methacrylate terpolymer. The compatibilizer often improves the property balance of an immiscible blend. Reactive compatibilization is an emerging technique. 

Thus according to the proposed theories >, solvents that are precipitants for polystyrene and are also insoluble in the polyolefin will produce Trommsdorff effects. Experimental data obtained from the grafting of styrene in benzene, dioxan, carbon tetrachloride, chloroform, pyridine and acetone (Figures 2 and 3) show that the grafting yields are low in these solvents and the corresponding grafting patterns are different to those in methanol and related alcohols. Thus the copolymerisation behaviour in all solvents studied in this work, except acetone, is in accordance with the proposed theory. Acetone, being a weak... 

Alt. styrene-co-maleic anhydride grafted polyolefins General purpose... 

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. 

Radio-chemical graft copolymerization with good efficiency on halogenated polyolefins has been carried out by contacting the substrate with monomer (styrene) vapor [158,159]. Interpenetrating polymer network (IPN) could be made by grafting the monomers on preirradiated substrates... 

Hivalloy A process for grafting styrenic polymers on to polyolefines, using a Ziegler-Natta catalyst. The products combine the physical properties of both polymer types. Developed by Montell and commercialized in the United States in 1997. See also Catalloy. Oxley, D. F., Chem. Ind. (London), 1998, (8), 307. 

In the middle range of styrene concentrations, a compromise is attained where there is sufficient styrene to scavenge all excess methanol radicals not involved in activation of the trunk polymer, yet an excess of monomer remains for grafting by the charge-transfer mechanism proposed by Dilli and Garnett (12) originally for copolymerisation to cellulose (4) and subsequently extended to wool (3), polyolefin (2,5) and PVC (13) systems. The data in Table V are consistent with this interpretation. 

Phillips catalysts for linear polyethylene and polypropylene and the graft copolymerizations for impact polystyrene and ABS are even younger and have not yet spread into the less industrialized countries of world. The production of polyolefins, poly (vinyl chloride), and styrene resins on a worldwide basis as well as of all synthetic polymers is shown in Figure 3. A comparison of the U.S. production in Figure 1 and in Figure 3 demonstrates the effect of age and dissemination of technology. It shows that relatively more poly (vinyl chloride) but less polyolefins and styrene resins are produced worldwide than in this country. 

As films are used e.g. the polymerization product of ethylbenzene and divinylbenzene (33) the copolymer of styrene and butadiene (755) the copolymer of styrene and butadiene mixed with polyethylene (157) a vulcanized or cyclized copolymer of an aromatic vinylcompound and an aliphatic conjugated polyene (2). As a crack resisting matrix is mentioned the copolymer of styrene, divinylbenzene and butadiene with e.g. dioctylphthalate as a plasticizer (176). Other examples are the copolymers of unsaturated aromatic compounds and unsaturated aliphatic compounds (77) and the reaction products of polyolefines and partially polymerized styrene (174). Primary groups can be introduced also with the help of Friedel-Crafts catalyst. Ts. Kuwata and co-workers treated a film of a copolymer of styrene and butadiene with an aluminium-ether complex and ethylenedichloride (79). Afterwards they allowed the film to react with trimethylamine. Another technique is the grafting of e.g. a polyethylene film with styrene (28). 

Diblock copolymers, especially those containing a block chemically identical to one of the blend components, are more effective than triblocks or graft copolymers. Thermodynamic calculations indicate that efficient compat-ibilisation can be achieved with multiblock copolymers [47], potentially for heterogeneous mixed blends. Miscibility of particular segments of the copolymer in one of the phases of the bend is required. Compatibilisers for blends consisting of mixtures of polyolefins are of major interest for recyclates. Random poly(ethylene-co-propylene) is an effective compatibiliser for LDPE-PP, HDPE-PP or LLDPE-PP blends. The impact performance of PE-PP was improved by the addition of very low density PE or elastomeric poly(styrene-block-(ethylene-co-butylene-l)-block styrene) triblock copolymers (SEBS) [52]. 

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. 

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