Modified polyolefin

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. 

Scheme 1 The proposed acid/amine and anhydride/ amine reaction between carboxylic groups/anhydride groups on modified polyolefins and amine end groups on Nylon-6.

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-... 

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... 

The mechanical properties of these blends are also increased with an increase in compatibilizer concentration. The improvement in tensile strength and tear strength on the addition of modified polyolefins are shown in Fig. 15. The mechanical properties also show a leveling off after the optimum concentration. The im-... 

The main purpose of this chapter is to describe methods of modifying polyolefin surfaces in such a way as to render them printable, and also to describe the tests that are available for determining the effects of treatment and... 

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. 

Hydrogenated SBCs are often used to modify polyolefins such as polypropylene, polybutylene and polyethylene. One of the unique characteristics of strongly phase-separated block copolymers such as high molecular weight (>50 000) SEBS and SEPS is their response to shear in the melt. These polymers retain their phase-separated structure well above the Tg of the polystyrene because their order-disorder transition temperatures are above processing temperatures. This phase separation strongly inhibits flow in the absence of shear resulting in infinite viscosity at zero shear rates. The application of shear... 

Fig. 4.8 (a) Histograms of pull-off force values obtained with an unmodified Si3N4 tip on untreated and oxyfluorinated iPP films in ethanol. The total surface free energy y of the polymer film is shown, (b) Mean values of pull-off force measured with COOH-terminated tips on modified polyolefin surfaces (iPP, isotactic polypropylene LDPE, low-density polyethylene) in ethanol (top) and with OH-terminated tips on oxyfluorinated iPP in water (pH 3.8, bottom) as a function of cos 0 (contact angle measured with water). (Reprinted in part/adapted with permission from [26, 27]. Copyright 1998, 2000, American Chemical Society.)... 

Polyolefins and Modified Polyolefins Weather-Resistant Grafts of Vinyl Monomers to EPDM and Polyacrylates... 

Tymor. [Morton Int L] Extrudable, modified polyolefin adhesive resins. 

Unite. [Aristech] Chemically modified polyolefins wiA anhydride functionality compatibiiizer for polymer blends and alloys, coupling agent in reinfaced and fill polymers, adhesive 2%eat for bonding polyolefins to various substrates. 

Fusabond . [DuPont] Anhydride-modified polyolefins compatibilizers for... 

The vibration damping capability of such systems as PA modified with an elastomer, modified polyolefin, or modified PS, are useful for the engine covers. Tackifiers such as cumarone resin, terpene resin or petroleum resin could be included in the blend formulation along with glass fibers. 

Many of the structures for MAH-modified polyolefins that appear in the literature are wholly speculative, and are based on a proposed mechanism for the grafting reaction rather than an analysis of the reaction or reaction products. In early work, product characterization took the form of determining overall grafting levels by titration or IR spectroscopy. In more recent work, with the availability of... 

The way the properties of the original unmodified polypropylenes are affected by the presence of the different polar groups bonded to their macromolecular structure remains an open line of work not only to the need characterization of the modified polyolefin, but to take the full control of the modification processes in terms of the number and localization of the sites where the polar groups are attached to the macromolecule. 

Zhu S-H, et al. Effect of a polydimethylsiloxane-modified polyolefin additive on the extrusion of LLDPE. ANTEC 2007, conference proceedings. Society of Plastics Engineers 2007. 

Polyolefin can be considered as an interdisciplinary material that needs the collaboration from different disciplines such as chemistry, physics, computer science, and engineering. The integration of different fields leads to new advanced technology and economic competitiveness to modify polyolefins for different applications. Polyolefins are replacing many other materials in diverse uses, and the scientists are trying to find new production, processing, and applications for the polyolefins with more friendly environment routs through new polymerization processes, modified catalysts and improved additives to have a wider application of these materials. 

Surface-modified polyolefin materials are widely used in biomedical field. Low-temperature plasma-treated PE was well suited for biomedical application. UHMWPE after surface modification with low-temperature plasma is the principal material used to replace damaged cartilage in total joint arthroplasty or the surgical reconstmction of a diseased joint [73]. The UHMWPE having desirable mechanical properties and biocompatibility is used in orthopaedic implants and joint socket in bone replacement. 

It has been reported that maleic anhydride-modified polyolefin (a polypropylene with a functional group) has been compounded with organophihc clay by melting and mixing, and the dispersed state of the silicates in the modified polypropylene matrix was investigated [34]. 

In this study, the following three compounds (each with a different amount of denatured maleic anhydride and different molecular weights) were used as maleic anhydride-modified polyolefins ... 

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