Polyolefins maleic anhydride

Coran and Patel [74] investigated the reactive com-patibilization of PP-NBR and HDPE-NBR blends using phenolic modified polyolefin, maleic anhydride modified polyolefin, and amine terminated nitrile rubber as reactive components. Dynamic vulcanization was also inves-... 

Numerous nylon blends prepared by compatibilization or reactive blending are commercially successful. The modifiers fiequenfly utilized in commercial nylon blends include polyolefin, thermoplastic polyolefin, thermoplastic polyunethane, ionomer, elastomer, ethylene-propylene rubber, nitrile mbber, polyftetrafluoroethylene), poly (phenylene ether), poly(ether amide), silicone, glass fiber, and carbon fiber. The nonpolar modifiers such as polyolefin, maleic anhydride or a polar vinyl monomer such as acrylic acid, methaciylic acid and fimiaric acid is fiequently incorporated to introduce reactive sites in nylon. 

SBS and SEBS block copolymers have been employed to impact modify HIPS, PPO/HIPS and various polyolefins. Maleic anhydride modified SEBS offers impact modification of polyamides and polyesters via reactive compatibilization. Chlorinated polyethylene (< 42 wt% Cl) is employed as an impact modifier for PVC, where weatherability is a primary concern [121]. Ethylene-(meth)acrylic acid copolymers and their neutralized versions (ionomers) have been utilized as impact modifiers for polyamides. PBT and PET impact modification with the poly(ester-ether block copolymer) (PBT-poly(tetramethylene oxide) (AB) ) yielded utility in automotive fascia applications. These products have been available under the tradenames Lomod (GE), Bexloy (duPont) andRiteflex (Hoechst-Celanese) [3]. 

Until recently, maleic anhydride has been used mostly for the functionalization of polyolefins due to the high reactivity of the anhydride group toward sucessive... 

Blends based on polyolefins have been compatibilized by reactive extrusion where functionalized polyolefins are used to form copolymers that bridge the phases. Maleic anhydride modified polyolefins and acrylic acid modified polyolefins are the commonly used modified polymers used as the compatibilizer in polyolefin-polyamide systems. The chemical reaction involved in the formation of block copolymers by the reaction of the amine end group on nylon and anhydride groups or carboxylic groups on modified polyolefins is shown in Scheme 1. 

The reactive compatibilization of HDPE-NBR and PP-NBR blends has been studied by Thomas and coworkers [75,76]. The maleic anhydride modified polyolefins and phenolic modified polyolefins are used as com-patibilizers. The effect of the concentration of these compatibilizers on the compatibility of these blends was investigated in terms of morphology and mechanical properties. It was found that in these blends an optimum quantity of the compatibilizer was required to obtain maximum improvement in properties, and after that a leveling off was observed. The domain size of the dispersed NBR phase in these blends is decreased up to a certain level and then increases (Fig. 12 and 13). The reduction in domain size is attributed to the increase in... 

Polyamide/polyolefin modified with dicarboxylate (propylene-maleic anhydride) SBR—MA copolymer... 

A good example of a reactive modifier which has been used (14) to enhance properties of polyolefins is maleic anhydride (MA). The formation of maleic adduct in polypropylene (PP), for example, can be used to effect several modifications e.g. to improving hydrophilicity, adhesion and dyeabflity. Moreover, the polymer-maleic adduct has an availabla additional functionality to effect other chemical modifications for achieving the desired material design objectives. Reactions of MA with polymers in solution are described in the patent literature (15). 

In the present paper, we report on the compatibilization of clay with polyolefins, specifically low and high density poly-ethylenes (LDPE, HDPE), through the radical-induced polymerization of maleic anhydride (MAH) in the presence of the polymer and clay, so that the MAH is grafted on the PE and the anhydride groups concurrently react with the filler surface (l, 2). 

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]. 

Graft reactions and functionalization reactions Graft copolymer of polystyrene and maleic anhydride graft copolymer of polyolefines and vinylsilanes graft copolymers of polyolefines and (meth)acrylic monomers, graft copolymer of EVA with acrylic acid graft copolymer of polyolefines and maleic anhydride halogenation of polyolefines or EVA... 

Interchain copolymer formation Copolymers of reactive polystyrene and polymers with amide, mercaptan, epoxy, hydroxy, anhydride or carboxylic acid groups, copolymer of polypropylene grafted with maleic anhydride and nylon-6, copolymer of polyolefines and polystyrene, copolymer of EVA grafted with methacrylates and grafted polystyrene... 

Some authors combined the IPN concept with the use of compatibi-lizers similar to that mentioned in Section 2. These may be a coupling agent such as epoxy-functionalized polysiloxane, polysiloxane copolymers or an organofunctional grafted polyolefin such as poly(ethylene-co-methacrylate) or MA-g-EPDM (maleic anhydride grafted EPDM) [124,125, 133]. Knaub et al. [150] studied a poly(urethane-ureas)/PDMS semi-IPN in... 

The third advantage associated with metallocene catalysts is that the predominant mechanism for chain termination is by /3-hydride elimination. This produces a vinyl double bond at the end of each polymer chain. Further functionalization of the vinyl group by graft polymerization with maleic anhydride and other functional monomers is far more effective than is typical for polyolefins obtained by conventional catalysts. 

Examples of acid modified polyolefins are the copolymers of ethylene with acrylic acid or methacrylic acid. Variations include the partially neutralised acid copolymers with metal ions (ionomers) or terpolymers of ethylene, an acid and an acrylate such as methyl acrylate or isobutyl acrylate. Acid-containing extrudable adhesives are widely used to bond to aluminium foil. Examples of anhydride-modified polyolefins include terpolymers of ethylene, maleic anhydride and acrylates such as ethyl acrylate or butyl acrylate and the anhydride-grafted polyolefins. Some typical applications and stmctures of a variety of multilayer materials with extruded polymer tie-layer adhesives, as described in Du-Pont trade literature, are detailed in Table 16.2. 

Polystyrene is one of the most widely used thermoplastic materials ranking behind polyolefins and PVC. Owing to their special property profile, styrene polymers are placed between commodity and speciality polymers. Since its commercial introduction in the 1930s until the present day, polystyrene has been subjected to numerous improvements. The main development directions were aimed at copolymerization of styrene with polar comonomers such as acrylonitrile, (meth)acrylates or maleic anhydride, at impact modification with different rubbers or styrene-butadiene block copolymers and at blending with other polymers such as polyphenylene ether (PPE) or polyolefins. 

If chemical reaction can take place between the functional groups on the compatibilizer and the two phases, then this will result in high interfacial adhesion and the miscibility is important only insofar as the reacting groups need to approach one another in order to enable reaction. Often this functionalization is achieved in a separate reactive-processing step, such as the grafting of maleic anhydride to polyolefins. Scheme 1.48 (Moad, 1999). 

The formation of compatibilizer frequently occurs by interfacial reaction of the modified polymers. An example is the use of maleic anhydride grafted to a polyolefin elastomer (EPM/EPM-g-MA) as the interfacial additive for reactive blending with a polyamide, nylon-6 (Van Duin et al., 2001), in a twin-screw extruder. It was found that the consumption of MA occurred rapidly and different blend morphologies were produced. However, it was found that the nylon-6 degraded during processing, due to the reaction of anhydride with the... 

Grafting reaction Reaction of a monomer and a polymer to form a grafted polymer or copolymer Grafting vinyl silanes onto polyolefins for crosslinked polyolefins acrylic acids onto polyolefins for hydrophilicity maleic anhydride onto polyolefins for compatabilization... 

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