Reactive extrusion polymer grafting

Reactive Extrusion. Reactive extrusion for grafting poly(/3-hy-droxybutyrate-co-valerate) has been used. Other polymers suitable for grafting are poly(butylene succinate) (PBSU) or poly(caprolacto-ne) (PCL) (18). The grafting of 2-hydroxyethyl methacrylate with a peroxide is shown in Figure 4.1. 1,1,4,4-Tetramethyltetramethylene bis(ferf-butyl peroxide) (Lupersol 101)is a preferred peroxide (18). 

Premphet, K., Chalearmthitipa, S. (2001), Melt grafting of maleic anhydride onto elastomeric ethylene-octene copolymer by reactive extrusion , Polym Eng Sci, 41 (11), 1978-1986. 

Radical induced grafting may be carried out in solution, in the melt phase,292 29 or as a solid state process.296 This section will focus on melt phase grafting to polyolefin substrates but many of the considerations are generic. The direct grafting of monomers onto polymers, in particular polyolefins, in the melt phase by reactive extrusion has been widely studied. Most recently, the subject has been reviewed by Moad1 9 and by Russell.292 More details on reactive extrusion as a technique can be found in volumes edited by Xanthos," A1 Malaika and Baker et a 21 7 The process most often involves combining a frcc-radical initiator (most commonly a peroxide) and a monomer or macromonomer with the polyolefin as they are conveyed through the extruder. Monomers commonly used in this context include MAII (Section 7.6.4.1), maleimidc derivatives and malcate esters (Section 7.6.4.2), (meth)acrylic acid and (meth)acrylate esters (Section 7.6.43), S, AMS and derivatives (Section 7.6.4.4), vinylsilancs (Section 7.6.4.5) and vinyl oxazolines (Section 7.6.4.6). 

Graft polymers can be obtained by reactive extrusion (47). Likewise, the grafting can be performed in solution. In the solvothermal method, the polymer is dissolved in a solvent and the solution is in a vessel. The material can be heated even above the critical point of the solvent (42). In the past, this method was mostly used in inorganic chemistry, however using this method MA could be successfully grafted onto ABS. 

G. Moad, The synthesis of polyolefin graft copolymers by reactive extrusion, Prog. Polym. Sci., 24(1) 81-142, April 1999. 

Reactive extrusion takes place when the twin screw system is designed to incorporate one or more chemical reactions during the process, such as grafting or even polymerization. Grafting is the process of attaching pendant molecules onto the backbone of a polymer chain. For example, a small concentration of maleic anhydride can be incorporated into polypropylene to make the... 

We carried out experiments to define the optimal conditions in a reactive extrusion process, and to obtain maleic anhydride grafted polymers of polypropylene copolymers (3050 MN 4 supplied by ATOCHEM). The previous studies were carried out in a batch mixer (HAAKE RHEOCORD), at a temperature of 220° C and a mixing speed of 64 rpm, during 20 minutes. Three different systems were tested i. with pure maleic anhydride ii. in the presence of a solvent (toluene or chorobenzene) iii. by introduction... 

These results demonstrate the chemical linkage between TPEV and PA-6 by graft polymer formation during the reactive extrusion process (Fig. 5). 

By a similar degradation and graft copolymer formation mechanism block copolymers could be obtained by reactive extrusion. A prerequisite is the presence of functional groups and the interaction of these groups with immiscible polymers during melt processing. Several polyamide block copolymers are synthesised by a melt-modification process. 

Most reactive extrusion has dealt with polymers that can be difficult to handle by other techniques.68 Polymers can be cross-linked, grafted with other monomers, and so on. Extrusion cross-linking of polyethylene wire coating raises the maximum temperature of use. Polypropylene degrades in this process, but can be cross-linked successfully if mul-... 

CORl s are the prime machines for polymer blending and reactive extrusion [Brown, 1992]. They have been used as reactors for the addition polymerization (polyacrylates, SAN, S-MMA, PA-6, POM, or TPU) and for the polycondensation (PA-66, polyarylates, PEST, PEI). Polymer grafting (polyolefin + silane, maleic anhydride, acetic anhydride, etc.) as well as mechanical and chemical degradation of polypropylene have also been carried out. 

For reactive extrusion, the mixing segments subject the poiymer to high enough shear to mechanicaiiy degrade the moiecules and create reactive sites where the chain extension additive can be grafted to the backbone of the polymer as an extended side chain. Some cross-linking may occur under the same conditions. 

Poncin-Epaillard, F. (2002). Characterization of C02 plasma and interactions with polypropylene film. Plasmas Polymers, Vol. 7, pp. 1-17, ISSN 1084-0184 Pesetskii, S.S. Jurkowski, B. Krivoguz, Y. M. Kelar, K. (2001). Free-radical grafting of itaconic acid onto LDPE by reactive extrusion I. Efect of initiator solubility. Polymer, Vol. 42, pp. 469-475, ISSN 0032-3861. 

Functionalization of isotactic polypropylene with maleic anhydride by reactive extrusion mechanism of melt grafting. Polymer, Vol. 42, pp. 5549-5557, ISSN 0032-3861. 

Wei and co-workers [38] grafted P(3HB) onto cellulose by the radical initiation of dicumyl peroxide with in situ reactive extrusion. The findings revealed that the reaction time and concentration of dicumyl peroxide significantly influenced the grafting efficiency. SEM confirmed the presence of the grafting reaction between the surface of the cellulose and PHB. DSC analysis showed a reduction of the crystallinity of the graft polymer. TGA analysis further showed that the graft polymer is more thermally stable than P(3HB). 

Copolymerizations are powerful ways to produce polymers with speeifie properties with well defined strueture. However, they involve the costly modification of existing production facilities of polystyrenes. To satisfy small market niches, modified polystyrenes ean be obtained through grafting reactions by chemical reactions on a polymer melt in an extruder (reactive extrusion) to achieve functionalities on the polymeric chains. Thus, grafting reactions are the preferred methods to achieve functionality commercially because they are low cost alternatives to the eopolymerization processes despite low grafting efficieney. For example, polystyrenes have been grafted with brominated styrene to enhanee the flame resistance of polystyrenes, as shown in Reaction 13. 

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