Poly blends with

Nitrile mbber finds broad application in industry because of its excellent resistance to oil and chemicals, its good flexibility at low temperatures, high abrasion and heat resistance (up to 120°C), and good mechanical properties. Nitrile mbber consists of butadiene—acrylonitrile copolymers with an acrylonitrile content ranging from 15 to 45% (see Elastomers, SYNTHETIC, NITRILE RUBBER). In addition to the traditional applications of nitrile mbber for hoses, gaskets, seals, and oil well equipment, new applications have emerged with the development of nitrile mbber blends with poly(vinyl chloride) (PVC). These blends combine the chemical resistance and low temperature flexibility characteristics of nitrile mbber with the stability and ozone resistance of PVC. This has greatly expanded the use of nitrile mbber in outdoor applications for hoses, belts, and cable jackets, where ozone resistance is necessary. 

Also, PBT is blended with poly(ethylene terephthalate) (PET), polysulfone, and SMA (303). PET may also be blended with a number of other engineering polymers, such as PC and impact modifiers. 

Poly(ethyl methacrylate) (PEMA) yields truly compatible blends with poly(vinyl acetate) up to 20% PEMA concentration (133). Synergistic improvement in material properties was observed. Poly(ethylene oxide) forms compatible homogeneous blends with poly(vinyl acetate) (134). The T of the blends and the crystaUizabiUty of the PEO depend on the composition. The miscibility window of poly(vinyl acetate) and its copolymers with alkyl acrylates can be broadened through the incorporation of acryUc acid as a third component (135). A description of compatible and incompatible blends of poly(vinyl acetate) and other copolymers has been compiled (136). Blends of poly(vinyl acetate) copolymers with urethanes can provide improved heat resistance to the product providing reduced creep rates in adhesives used for vinyl laminating (137). 

Blends with PVC. Nitrile mbber may be blended with poly(vinyl chloride) (PVC) by the polymer producer by two different techniques (1) blending of NBR latex with PVC latex followed by co-coagulation and drying, or (2) physically mixing the soHd NBR and PVC powder in mixing equipment such as an internal mixer. NBR—PVC polymer blends are well known for the good ozone resistance that is imparted by the PVC. 

Poly(hydroxyphenyl maleimide)-b-PBA was added to thermosetting phenol resin to improve heat resistance [63]. PVC blended with poly(vinyl copolymer having cyclohexyl maleimide group)-b-PVC showed improved heat resistance and tensile strength with thermal stability during processing [64]. 

Some preliminary results indicate that the functionalized polymers form miscible blends with poly(methyl methacry1 ate). 

On the other hand, silicones are used in organic composites. The application of alloys composed of the fully cured silicone rubber particles in a continuous thermoplastic phase, called thermoplastic silicone vulcanizate, which offers high-performance materials, has been reported.506,507 Functionalized POSS was not only co-polymerized, but also blended with poly(methylmethacrylate) to study the effect of silsesquioxanes on the thermal stability of thermoplastics.508... 

For example, blending with poly(methyl methacrylate) (PMMA) has been suggested. PMMA exhibits excellent weatherability, mechanical properties and surface scratch resistance and thus, is widely... 

Hybrid organic-inorganic polymer-polymer composites were prepared by blending with poly(A-vinylpyrrolidone) (PVPr), poly(4-vinylpyridine) (PVPy) and poly(ethyl oxazoline) (PEOx). It was found that the properties of these hybrids depended strongly on the preparation conditions.14... 

The end groups of a PDMS polymer have been shown to affect the interfacial tension of blends with poly(butadiene)126. Thus, substitution of an amine-terminated PDMS for a trimethylsilyl-terminated PDMS can reduce the interfacial tension by up to 30%. This effect is postulated to arise due to the amine end group having a surface energy closer to that of butadiene than does the trimethylsilyl group and thus being present at the interface. 

Examples of known phosphazene polymer blends are those in which phosphazenes with methylamino, trifluoroethoxy, phenoxy, or oligo-ethyleneoxy side groups form blends with poly(vinyl chloride), polystyrene, poly(methyl methacrylate), or polyethylene oxide).97 100 IPNs have been produced from [NP(OCH2CH2OCH2CH2OCH3)2] (MEEP) and poly(methyl methacrylate).101-103 In addition, a special type of IPN has been reported in which a water-soluble polyphosphazene such as MEEP forms an IPN with a silicate or titanate network generated by hydrolysis of tetraethoxysilane or tetraalkoxytitanane.104 These materials are polyphosphazene/ceramic composites, which have been described as suitable materials for the preparation of antistatic layers in the manufacture of photographic film. 

Miyashita et al. carried out miscibility characterization of CA blends with poly(N-vinyl pyrrolidone) (PVP), poly(vinyl acetate) (PVAc), and poly(N-vinyl pyrrolidone-co-vinyl acetate) random copolymers [P(VP-co-VAc)s] [ 104]. On the basis of thermal transition data obtained by differential scanning calorimetry (DSC), a miscibility map (Fig. 8) was completed as a function of the degree of substitution (DS) of CA and the VP fraction in P(VP-co-VAc). Figure 9 compares results of the DSC measurements between two blending pairs of CA/P(VP-co-VAc) corresponding to the polymer combinations marked as A and B in Fig. 8. In the data (Fig. 9b) for the blends of CA (DS = 2.95) with P( VP-co-VAc) of VP = 51 mol %, we can readily see a sign of poor miscibility, as is evidenced from the lack of an appreciable shift in the... 

Poly(glycolic acid) and poly(3-HB) form immiscible blends with poly(e-CL). Poly(3-HB) is an expensive polymer, which crystallizes slowly from the melts and embrittles on ageing. Poly(e-CL), on the other hand, has a low mp and limited use. An optimal combination of cost and properties may be obtained by blending [114]. 

Hill DJT et al. (1996) Development of wear-resistant thermoplastic polyurethane by blending with poly(dimethyl siloxane). I. Physical properties. J Appl Poly Sci 61 (10) 1757—1766... 

The compatibility, mechanical properties, and segmental orientation characteristics of poly-e-caprolactone (PCL) blended with poly (vinyl chloride) (PVC) and nitrocellulose (NC) are described in this study. In PVC blends, the amorphous components were compatible from 0-100% PCL concentration, while in the NC system compatibility teas achieved in the range 50-100% PCL. Above 50% PCL concentration, PCL crystallinity was present in both blend systems. Differential IR dichroism was used to follow the dynamic strain-induced orientation of the constituent chains in the blends. It was found for amorphous compatible blends that the PCL oriented in essentially the same manner as NC and the isotactic segments of PVC. Syndio-tactic PVC segments showed higher orientation functions, implying a microcrystalline PVC phase. 

In the case of polystyrene blends with poly(vinyl methyl ether) two phase behaviour was found for blends from various chlorinated solvents whereas single phase behaviour was found for blends from toluene The phase separation of mixtures of these polymers in various solvents has been studied and the interaction parameters of the two polymers with the solvents measured by inverse gas chromatography It was found that those solvents which induced phase separation were those for which a large difference existed between the two separate polymer-solvent interaction parameters. This has been called the A% effect (where A% = X 2 Xi 3)-A two phase region exists within the polymer/polymer/solvent three component phase diagram as shown in Fig. 2. When a dilute solution at composition A is evaporated, phase separation takes place at B and when the system leaves the two phase region, at overall... 

Fig. 9. Dynamic mechanical analysis plots of tan 5 against temperature for chlorinated polyethylene (52 % Cl) (4) and blends with poly(butyl acrylate) containing (3) 84.7% PBA, (2) 64.1 % PBA, and (1) 46.1 % PBA. The inset shows a plot of T, against weight percent chlorinated polyethylene where there is a marked deviation from linearity indicative of a specific interaction...

FIgyre 2.16 Variation of melting temperature with crystallization temperature for (O) poly(8-caprolactone) and ( ) poly(E-caprolactone) in a blend with poly(4-hydroxystyrene) (85% weight fraction of PCL). (From Ref. 15.)... 

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. ... 

Nakatsuka S, Andrady LA. Permeability of vitamin-B-12 in chitosan membranes effect of crosslinking and blending with poly(vinyl alcohol) on permeability. ] Appl Polym Sci 1992 44 7-28. 

Some studies show that pyrolysis of certain polymer blends can be influenced by the migration of a small molecule or a small radical formed from one type of polymer and affecting the other type. For example, poly(methyl methacrylate) (PMMA) in blends with poly(vinyl chloride) (PVC) shows higher resistance to heat. The thermal decomposition of PVC generates HCI, which interacts with the PMMA forming anhydride units in the middle of PMMA chains, as shown below ... 

DeMeuse and Jaffe. In another chapter, Brostow et al. discuss the phase behavior of binary and ternary mixtures containing an LCP component. The kinetics of thermally induced phase separation of an HBA/PET LCP blended with poly(ether imide) are described by Zheng and Kyu. 

In blends composed of immiscible polymers, amorphous polymer does not affect the crystallization of crystallizable polymer, but if two polymers are miscible, amorphous polymer acts as diluent and affects crystallization of the second polymer. Poly(E-caprolactone) is a crystallizable component of the blend with poly( vinyl butyral), which is studied in compositions containing carbon black. Typically, blends of these two polymers form very large spherulites, and it is interesting to find out how carbon black affects crystallization and other properties of the blend as well as the distribution of carbon black in relationship to the spherulites. Figure... 

A unique design was proposed by Landi et al., using CdSe quantum dot-single-walled carbon nanotube complexes in blends with poly-(3-octylthiophene) (P30T) [259]. One motivation for this construction was the ability to extend the usable absorption spectrum. 

MacKnight and coworkers found that several poly(imide)s, such as Ultem poly(ether imide) and XU218 poly(imide), formed miscible blends with poly (benzimidazole) (FBI) [58, 59]. The miscibility of these blends is believed to result from specific interactions between the benzimide ring of the poly(im-ide) and benzimidazole ring of FBI. In a later study, Grobelny et al. [60] reported the CFMAS spectra of several of these blends. Slight changes in the lineshape were observed in the intimate blends, and seen as evidence of the specific interactions between the polymers. In particular, the peak in the spectra, due to the imide carbonyl carbon, was seen to broaden towards... 

De Paoli and coworkers7 have used the more soluble poly(o-methoxyaniline) doped with p-toluene sulfonic acid to prepare a composite blend with poly(epichlorohydrin-co-ethylene oxide), but conductivities were relatively low (10-3 S cm-1) even with a high 50% (w/w) conducting polymer loading. 

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