Compatibilisers, reactive

Single- and twin-screw extruders with customised screw profiles are used to produce low density PETP-PP foams in the presence of reactive compatibiliser and coagents. Low density PETP foam is also produced from... 

J. Pospfsil, I. Forteln, D. Micheilkovei, Z. Kruli , and M. Slouf, Mechanism of reactive compatibilisation of a blend of recycled LDPE/HIPS using an EPDM/SB/aromatic diamine co-additive system, Polym. Degrad. Stab., 90(2) 244-249, November 2005. 

Thus, it appears that chemical reactivity or ionic-cross interactions could lead to in situ compatibilising or miscibility enhancement during melt-mixing. However, several questions remain. How does the reactivity modify the thermodynamic balance, the reciprocal miscibility or the rheological behaviour of the melt Or, how the covalent or ionic bonding influence the interfacial adhesion processability and final mechanical properties of the immiscible blends ... 

The problem of physical blends is not only the formation of a stable morphology. A more important problem for the users of such materials is the changing and most often the lowering of material properties. Table 9 [13] lists the effect of the reactive compatibilisation of polypropylene PA-6 blends of different compositions ... 

The reactive compatibilisation between PP and PA-6 retain the material properties of the starting material PP without lowering the properties with increasing PA-6 content. Sometimes a slight improvement could be observed. 

The chemical structure of polyamides and polyester involves only few chances for a reactive compatibilisation during melt processing with short residence times... 

Such final block copolymer products are described and used as compatibilised chain extender additives for the modification of melt viscosity of polyamides during compounding by reactive extmsion [10] (Fig. 6). 

A highlight of the reactive compatibilisation of extremely incompatible polymers is the chemical bonding between the anti-adhesive PTFE and the polar polyamides. It had been assumed for a long time that a chemical bonding between PTFE and polyamide is impossible because there was no appropriate reaction mechanism. PTFE is a highly crystalline polymer which could only be processed by using special equipment. The utilisation in tribological systems is a well-known... 

Bonner, J. G. Hope, P. S. (1993) Compatibilisation and reactive blending, in Folkes, M. J. Hope, P. S. (Eds.) Polymer Blends and Alloys, London Blackie Academic and Professional. 

Reactive blending of thermoplastic starch/polymer blends has been examined recently and aims to increase properties and performance via control of blend morphologies. Mani [58, 59] examined different techniques for compatibilising starch-polyester blends. They examined development of maleic anhydride grafted polyester/starch blends and starch-g-polycaprolactone... 

Compatibilisers are intentional additives, incorporated into multi-component, multiphase polymer systems. They are usually block copolymers, whose segments are soluble in different components of the mixture. Compatibilisers can be reactive (if they form bonds with one of the polymers in the mixture) with reactive groups like acrylic or methacrylic, maleic anhydride, or glycidyl methacrylate), or non-reactive. The main classes of compatibilisers are (a) modified PE and polypropylene-styrene containing polymers, (b) macromonomers, (c) silane-modified materials. 

Gopakumar, T. G., Ronrathnam, S., Lele, A., Rajan, C. R., and Fradet, A. 1999. In situ compatibilisation of poly(phenylene sulphide)/wholly aromatic thermotropic liquid crystalline polymer blends by reactive extrusion Morphology, thermal and mechanical properties. Polymer 357-364. 

PP-LDPE with poly(propylene-g-maleic anhydride) and poly(ethylene-co-vinyl alcohol) as in situ reactive compatibilisers (117),... 

Reactive blending is an important method for the compatibilisation of polymer blends. Two or more immiscible polymeric components are functionalised with chemical units that are coreactive. During melt... 

Addition of p-cresol formaldehyde (PCF) into phenolic/NBR blends resulted in rednction in the domain size of the dispersed phase and improvement in mechanical properties [244]. PCF resin has an intermediate polarity compared with NBR and resole and can react faster with NBR. Therefore, PCF molecules are likely to be concentrated at the phenolic/NBR interface and act as an external compatibilising agents [245]. Thus compatibility and chemical bonding between NBR and phenolic resin is improved, leading to the enhancement in properties. The other materials used as toughening agents of phenolic resin include elastomers such as natural rubber and nitrile rubber [246, 247], reactive liquid polymers [248] and thermoplastics such as polysulfone, polyamide, polyethylene oxide [249, 250]. 

More than one compatibiliser may be required to achieve success in all these respects. Both physical and reactive chemical mechanisms may be involved. It is not always desirable to... 

Thomas S and Groeninckx G (1999) Reactive compatibilisation of heterogeneous ethylene propylene rubber (EPM)/nylon 6 blends by the addition of compatibiliser precursor EPM-g-MA, Polymer 40 5799-5819. 

H. Cartier and G.H. Hu, Compatibilisation of polypropylene and poly-(butylene terephthalate) blends by reactive extrusion effects of the molecular structure of a reactive compatibiliser, J. Mater. Sci., 35(8) 1985-1996, April 2000. 

Bonner, J.G., Hope, P.S. Compatibilisation and reactive blending. Chapter 3. In Polymer Blends and Alloys, Folkes, M.J., Hope, P.S., eds. Blackie Academic Professional, London, 1993. 

No.2-3, Feb./March 1998, p.227-34 COMPATIBILISATION OF POLYSULPHONE/ POLYAMIDE BLENDS BY REACTIVE POLYSULPHONES. EVIDENCE FOR COPOLYMER FORMATION Weber M Heckmann W BASF AG... 

In an alternative process, lactones and lactides have been polymerised in an extruder fed by a nonreactive preformed polymer, such as poly(propylene) and poly(ethylene). Gimenez et al have accordingly prepared blends of PCL with these polyolefins (Gimenez, 1999). Further research effort is, however, required in order to optimise this approach. The in situ formation of a compatibiliser by reactive blending might be a possible strategy. 

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