Reactive melt-blending

Reactive Melt Blending. High molecular PA t)q)es or poly(ester amide) block copolymers can be prepared by melt blending techniques. As chain extenders, bislactams are used, such as terephthaloyl bislaurocaprolactam, isophthaloyl bislaurocaprolactam or the corresponding biscaprolactams. 

Preparation of Polyamide-PE graft copolymer by reactive melt blending process (from ref. 11). 

Reactive Extrusion of PLA-based Materials from Synthesis to Reactive Melt-blending... 

MB is melt blending, SB is solution blending, RMB is reactive melt blending, and RSB is reactive solution blending. Miscible blend. 

In the case of the reactive melt-blending, the effects of the chemical reaction at the interface on the phase morphology development are multi-fold. The chemical reaction at the interface leads to ... 

Table 1. Reactive melt blending of ester, amide, and urethane linear polymers ...

The notched Izod impact strength of PET at room temperature is only 45 J/m. Supertough PET with notched impact strengths up to 1000 J/m can be prepared by melt blending PET with 20wt% of a reactive elastomeric terpolymer (e.g. E-MA-GMA). Pecorini and Calvert [28] have attributed this supertoughness phenomenon to two distinct toughening mechanisms, as follows ... 

In another approach, the SAN backbone of ABS was modified through copolymerization with maleic anhydride. This modification introduced controlled amounts of an anhydride functionality on ABS, which upon subsequent melt blending with a PA reacts to form a graft copolymer of SAN and PA which effectively compatibilizes the blend. Commercial blends of ABS with PA-6 and PA-66, introduced by Monsanto under the trade name of Triax 1000, utilize this reactive compatibilization technology [Lavengood et al, 1987]. In another technique of reactive compatibilization, commercial grades of ABS were directly modified by reactive extrusion with maleic anhydride or fumaric acid and then melt blended with PA-6 and optionally adding small amounts of functionalized EP mbber [Akkapeddi et al, 1990]. 

Melt blending of PA-6 (or 66) with such an anhydride functionalized polypropylene causes a fast graft copolymer reaction between the polyamide and PP at the interface, which subsequently compatibilizes the blend. Some commercial polyamide/polypropylene blends may utilize such types of reactive compatibilization techniques. Properties of commercial PA/PP blends, both unfilled and glass filled grades, are shown in Tables 15.18 and 15.19. Typically, these blends... 

Standard grade ABS (20% PBD) could also be directiy modified by grafting an anhydride functionality via reactive extrusion with maleic anhydride in the presence of a trace amount of peroxide initiator [Akkapeddi et al., 1990]. Such an extruder maleated ABS upon subsequent melt blending with an amine terminated PA-6, gave a compatibilized ABS/PA-6 blend with significantly... 

Miladinov et al. reported the preparation of starch-fatty acid esters by reactive extrusion of plasticized starch and acid anhydrides (acetic, propionic, heptanoic and palmitic anhydrides) in the presence of sodium hydroxide as a catalyst [87]. Starch esters have been prepared by REX using maleic anhydride (MA) as a cyclic dibasic acid anhydride in the presence of 20 wt% glycerol as plasticizer. This material was melt-blended with biodegradable polyester. 

Ternary blends from a thermotropic liquid crystalline polymer, PEN, and PET were prepared by melt blending and melt spinning to fibers. The mechanical properties of ternary blend fibers could be significantly improved by annealing at 180°C for 2 h. This is attributed to the development of more ordered crystallites and to the formation of more perfect crystalline structures. The interfacial adhesion between PEN and liquid crystalline polymer phases is enhanced when the blends are processed with dibutyl-tindilaurate as a reactive catalyst to promote transesterification. 

Montaudo, G., Montaudo, M.S, Scamporrino, E., and Vitalini, D., Composition and microstructure of copolyesters formed in the melt mixing of poly(ethylene terephthalate) and poly(ethylene truxillate), Makromol. Chem., 194, 993, 1993. Montaudo, G., Puglisi, C., and Samperi, E, Copolymer Composition a Key to the Mechanism of Exchange in Reactive Polymer Blending, in Transreactions in Condensation Polymers, Kakirov, S., Ed., Wiley-VCH, Weinheim, 1999. Bloembergen, S., Holden, D.A., Hamer, G.K., Bluhm, T.L., and Marchessault, R.H., Studies of Composition and Crystallinity of Bacterial Poly()3-hydroxybu-tyrate-co-jS-hydroxyvalerate), Macromolecules, 19, 2865,1986. 

---