Compatibilizers principle

In this chapter, an overview of the commercially important blends is presented with a particular emphasis on the rationale for their commercial development, the compatibilization principles, their key mechanical properties and their current applications and markets. To facilitate the discussion, the commercial polymer blends have been classified into twelve major groups depending on the type of the resin family they are based on, viz. (i) polyolefin, (ii) styrenic, (iii) vinyl, (iv) acrylic, (v) elastomeric,... 

Dynamic melt rheology studies were carried out on PE/EMA and PE/EMA-salt in order to better understand the role of EMA-salt as a compatibilizer in the PE/EMA/PA system. The tlme-ten jerature superposition principle was applicable in all cases for G. Also, G super master curves were constructed for blends of PE/EMA and PE/EMA-salt when the EHA and EMA-salt are derived from the same parent polymer. Superposition of G" was possible for all blends containing EMA in the free acid form, but not for those in the salt form, with the extent of deviation from superposability being a function of EMA-salt concentration. 

The principle of the radiation-initiated compatibilization may be upgraded by adding some reactive additives to the multicomponent system before or after the radiation step. The advanced procedure may be considered as a kind of sensitized cross-linking. The result is clearly a diminishing of required radiation dose, achieving the same or better level of compatibilization as without additives. 

The radiation initiated compatibilization makes in principle all synthetic and natural polymers radiation cross-linkable, including those considered radiation-degradable in earlier studies. 

This suggests that it is possible to design an universal compatibilizer operating on the principle of competitive repulsive interactions between the homopolymers and the different blocks of the copolymer. 

In principle, any polymer that is miscible with two others can be used as co-solvent. As the data in Table 4.1 indicate, Phenoxy, PMMA, PPE, PC and PCL are miscible with several polymers, hence they are the best candidates for co-solvents of many systems. It is noteworthy that acrylic multipolymers are often used as additives to many blends. Their role is to enhance compatibilization as well as to toughen the blends. 

VUgis and Noolandi investigated the effects of addition of a block copolymer X-Y to blends of A and B polymers. Similar dependencies as those derived for A-B copolymer were found. The work suggested that it is possible to design universal compatibilizers based on the principle of competitive repulsive interactions between the homopolymers and copolymer s blocks. 

The term reactive processing is used to describe a polymer processing that involves chemical reactions. In principle, any processing operation can be conducted as a reactive process, viz. reactive injection molding (RIM). However, most often the term refers to reactive extrusion, and in particular, to the reactive compatibilization of immiscible polymer blends, usually conducted in a TSE. During the last 50 years, the latter machines have been used as chemical reactors for the polymerization, depolymerization (chemical recycling), polymer modification and compatibilization [Brown, 1992, Xanthos, 1992 Utracki, 1989, 1991, 1994, 1997]. 

To obtain well performing material out of a mixture of immiscible polymers two principal operations must be performed compatibilization and compounding. Fundamental aspects of these will be discussed in Part 16.3 The principles of polymer blending. However, interested reader is advised to search detailed information is specific chapters of this Handbook, viz. on compatibilization in Chapters 4 and 5, on flow, morphology and compounding in Chapters 7, 8 and 9, respectively. 

Principles of polymer blends compatibilization were presented in Part 16.3.2. Details of compatibilization are discussed in Chapter 4. Interphase and compatibilization by addition of a compatibUizer, and in Chapter 5. Reactive Compatibilization of this Handbook. 

In polyaniline-cellulose acetate films, phthalate and phosphate plasticizers were used. The addition of the plasticizer increases film flexibihty and lowers percolation threshold. It can be seen by ophcal microscopy that polyaniline grain sizes are reduced. Similar principle was adopted in polymer blend of thermoplastic polymer and polya-niline. Various plasticizers and their concentrahons were used to partially compatibilize blend in such a maimer that it still has domains of different conductivities but a low percolation threshold. Polyvinylchloride and poly(3-octylthiophene) are iimniscible but there is a low interfacial tension which allows to produce co-conhnuous morphology responsible for increased conductivity of blends along with increase in poly(3-octylthiophene) con-centrahon. Addition of DOP to this blend increases its conduchvity even if the concentration of poly(3-octylthiophene) decreases. 

The described peculiarities of MFCs can be expected and realized when the blend partners are condensation polymers or, at least, functionalized polyolefins. The latter restriction however, concerns only the self-compatibilization effect but by no means the basic principles of MFC manufacturing, i.e., MFCs can be prepared also from polyolefin partners provided the basic temperature requirements for their preparation are satisfied. 

The principle of activity of copolymeric compatibilizers is that they create interactions between their blocks or graft branches and the corresponding polymer components in a... 

Gaylord, N. G. (1992) Reactive Extrusion in the Preparation of Carboxyl-Containing Polymers and their Utilization as Compatibilizing Agents, in Xanthos, M. (Ed.) Reactive Extrusion, Principles and Practice, Hanser Publ. Munich... 

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