Introduction of Compatibilizers

Research into PU/PS IPNs was focused on the improvement of compatibility of two networks by use of three different compatibilizers [339,340]. The compatibilizers used in this study can best be represented as a kind of grafted compatibilizer with excellent anchorage, since both ends were incorporated into the PS network. The three different compatibilizers comprised, first, a very short-chained one consisting of the 1,1,3,3-tetramethyIxylene diisocyanate (m-TMXDI) molecule terminated with HEMA (1). This compatibilizer is similar in structure to the hard segment of the PU. The second compatiblizer (2) consisted of a POPG MM 1025 molecule terminated with TMI. The third one (3) was TMXDI and one POPG MM 1025. 

The high molar mass compatibilizer 3 also resulted in inverted tan 5 peak sizes. While the PU transition remained in place, a substantial inward shift of the entire PS transition could be noticed. This suggests that compatibiUzer 3 caused some degree of component mixing, resulting in less pure PS domains. With respect to the damping ability of the material, no improvement was made, since the intertransition values also remained low. 

A smprising result was obtained with compatibilizer 2. The PS Tg was seen to split into two transitions, one at 120 °C and the other at 70 °C. Also, the intertransition regions between the three peaks were high, so that the tran- 

Interesting results were obtained by Hourston et al. [339,340] who studied the compatibilization of IPNs based on immiscible polymer pairs such as PU and PS. They have shown that introducing various heterofimctional monomers or compatibilizing agents allows regulation of the degree of compatibility from a full one to the system that is characterized by the very broad temperature transition. 

It was shown that introduction of various amounts of HEMA into the starting system leads to the formation of a semi-IPN which is characterized by a single temperature transition based on DMA and DSC data [310,353]. The position of this transition depends on the system composition and on the kinetic conditions of the reaction (rates of formation of both components). The kinetic measurements have shown that during reaction in the presence of HEMA no phase separation proceeds, as follows from the hght scattering data. In this case the final system has a one-phase structure due to the formation of a thermodynamically miscible ternary system and to the grafting of PU chains onto PS macromolecules via the third component. The reaction compatibilization was studied more thoroughly for semi-IPN PU/PS in the presence of OUDM [311]. 

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The chapter will review the preparation, properties, and application of NR-EPDM blends. Several issues related to cure-rate mismatch, compatibility problems, morphology control by introduction of compatibilizers will be discussed. 

The introduction of the reactive oxazoline group into the triphosphazene ring has been achieved by the reaction of (NPC s and 2-(4-hydroxyphenyl)-2-oxazo-line, giving a hexasubstituted product (151).The reactivity of the oxazoline entities in (151) could be demonstrated by reaction with 4-benzoylbenzoic acid [formation of the photosensitive cyclophosphazene (152)] by the reactive blending with poly(ethylene terephthalate), and the compatibilizing activity for polycarbonate - polyamide blends. ... 

The aim of this paper is to present the different properties of polysaccharide composites obtained by the introduction of cellulose fibres, varying in length and content, into plasticized wheat starch. We have used LDPE-based composites as reference, because without compatibilizer, the LDPE-fibres interactions are usually considered as very poor. To highlight the interactions developed between cellulose and starch, we have compared both kinds of composites. Finally, we have evaluated the post-processing ageing of TPS compared to some other systems. 

While the reduction of the interfacial tension coefficient, v, is relatively easy by introduction of a macromolecular surfactant , the stabilization of morphology and improvement of the interphasial adhesion in the solid state, may not be so. One may use either a single compatibilizer that can perform all three compatibilization tasks, or a combination of agents, each playing one or two different roles. For example, stabilization of the desired dispersion (accomplished by addition of surfactant to mechanically mixed compound), may be accom-... 

Simple blends of ABS and PA are highly immiscible and hence are of little practical value. Compatibilization of ABS with polyamide was accomplished by several methods, most of which involving structural modification of ABS. In one approach, ABS was modified by copolymerization with acrylamide, during the preparation of ABS by the standard emulsion polymerization. The introduction of polar acrylamide units on the... 

Since immiscibility and degradation lead to brittle resins, introduction of a toughening agent is recommended. Most often, the compatibiliza-tion and impact modification are simultaneously accomplished by addition of a multi-polymer compatibilizer-cwm-impact modifier. To this category belong the universal compatibilizers . 

For the manufacture of sliding parts, POM blends were developed with PTFE (Ishioka 1991) with PVDF (Shibata et al. 1992) with either wax, PTFE, silicone oil, or PEG and with EBA-GMA (Takahashi and Kobayashi 1993). Later blending technology of POM involved introduction of the reactive end groups - it makes compatibilization with other polymers relatively simple. 

Since the introduction of BPA polycarbonate homopolymer, researchers have continually sought to expand the usefulness of these materials via synthesis of new polycarbonate homo- and copolymers. This section will focus on the copolymers that are commercially available. For a more extensive examination of noncommercial, non-BPA polycarbonates, several excellent reviews may be found at [90-93]. Copolymer production generated by reactive blending, coextrusion, and/or compatibilizing materials (e.g., grafting) will also not be discussed. However, a historical overview of commercial alloys and blends may be found in a recent work by Utracki [94]. 

Compatibilization improves the morphological stability of polymer blends when block or graft copolymers are used by the introduction of steric hindrance to drop coalescence. A chemical approach is possible for formation of grafted PC with SAN chains at the PC/SAN interface. SAN-amine copolymer is prepared by reaction of a terpolymer of styrene, maleic anhydride, and acrylonitrile with l-(2aminoethyl) piperazine. The SAN-amine polymer is miscible with the SAN matrix of ABS and reacts with PC. The formation of graft polymer has resulted in the reduction of SAN dispersed-phase particle size. The blend morphology has been found to stabilize in the mixing process. 

This effects depend on the alloy composition, choice of components, and their ratio. By an appropriate choice of components and knowing the polymer-solid interaction parameter, %s, the pairs may be selected for which introduction of particulate fillers will lead to increased compatibilization. There exists some analogy with improvement of miscibility of two polymers by introducing a third pol3mier miscible with each of the polymer components of the blend. We should like to note that for miscible polymer pairs the filler decreases the compatibility. This effect is probably a result of interaction as5mime-try. 

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