Chlorinated polyethylene blend with

PMMA/PVC blends provide heat resistance and chemical and flammability resistance into materials for injection moulding and extrusion applications. The major applications of these blends are interior panelling, trim and seat backs in mass transit vehicles. Commercially available PMMA is miscible with PVC [28, 31]. However, its phase behaviour is considered to be only partially miscible [29]. Chlorinated polyethylene blends with PVC have been used as impact modifiers and as secondary plasticisers [32], Chlorine contents of 42% and 30% by weight lead to miscible and immiscible properties, respectively. Impact modification will generally require phase separation, and plasticisation will require miscibility. 

When two polymers interact or react with each other, they are likely to provide a compatible, even a miscible, blend. Epoxidized natural rubber (ENR) interacts with chloro-sulfonated polyethylene (Hypalon) and polyvinyl chloride (PVC) forming partially miscible and miscible blends, respectively, due to the reaction between chlorosulfonic acid group and chlorine with epoxy group of ENR. Chiu et al. have studied the blends of chlorinated polyethylene (CR) with ENR at blend ratios of 75 25, 50 50, and 25 75, as well as pure rubbers using sulfur (Sg), 2-mercapto-benzothiazole, and 2-benzothiazole disulfide as vulcanizing agents [32]. They have studied Mooney viscosity, scorch... 

Polymer electrolytes are used in lithium ion rechargeable batteries. Pure polymer electrolyte systems include polyethylene oxide (PEO), polymethylene-polyethylene oxide (MPEG), or polyphosphazenes. Chlorinated PVC blended with a terpoly-mer comprising vinylidene chloride/acrylonitrile/methyl methacrylate can make a good polymer electrolyte. Rechargeable lithium ion cells use solid polymer electrolytes. Plasticized polymer electrolytes are safer than liquid electrolytes because of a reduced amount of volatiles and flammables. The polymer membrane can condnct lithinm ions. The polymer membrane acts as both the separator and electrolyte [7],... 

PVC with chlorinated polyethylene blends has improved impact performance, especially in the presence of notches and at lower temperatures than unmodified grades of PVC. They are used in continental Europe for external applications (e.g. rainwater goods) unmodified UPVC would be acceptable in the UK. Such blends are finding increasing use throughout Europe in extruded sections for window frames. 

Dimercapto-l,3,4-thiadiazole derivatives, accelerated by amines, are used to cross-link chlorinated polyethylene. Polyisobutylene containing brominated i ra-methylstyrene cure functionahty can be cross-linked in polymer blends with dimercapto-1,3,4-thiadiazole derivatives accelerated with thiuram disulfides. Trithiocyanuric acid is suggested for use in polyacrylates containing a chlorine cure site and in epichlorohydrin mbbers. 

Thermoplastic chlorinated polyethylenes are seldom used on their own but primarily in blends with other polymers, particularly PVC. If chlorination is taken to a level at which the polymer is only semi-compatible with the PVC, a blend with high impact strength may be obtained. In these circumstances the material is classified as an impact modifier. 

Pandey et al. have used ultrasonic velocity measurement to study compatibility of EPDM and acrylonitrile-butadiene rubber (NBR) blends at various blend ratios and in the presence of compa-tibilizers, namely chloro-sulfonated polyethylene (CSM) and chlorinated polyethylene (CM) [22]. They used an ultrasonic interferometer to measure sound velocity in solutions of the mbbers and then-blends. A plot of ultrasonic velocity versus composition of the blends is given in Eigure 11.1. Whereas the solution of the neat blends exhibits a wavy curve (with rise and fall), the curves for blends with compatibihzers (CSM and CM) are hnear. They resemble the curves for free energy change versus composition, where sinusoidal curves in the middle represent immiscibility and upper and lower curves stand for miscibihty. Similar curves are obtained for solutions containing 2 and 5 wt% of the blends. These results were confirmed by measurements with atomic force microscopy (AEM) and dynamic mechanical analysis as shown in Eigures 11.2 and 11.3. Substantial earher work on binary and ternary blends, particularly using EPDM and nitrile mbber, has been reported. 

FIGURE 11,1 Ultrasonic velocity versus acrylonitrile-butadiene mbber/ethylene-propylene-diene monomer (NBR-EPDM) blend composition (a) no compatibiUzer, (b) with chloro-sulfonated polyethylene (CSM), and (c) with chlorinated polyethylene (CM). (From Pandey, K.N., Setua, D.K., and Mathur, G.N., Polym. Eng. Set, 45, 1265, 2005.)... 

Contrasted with the resins modified with chlorinated polyethylene, addition of the substituted epoxides to resins modified with PTHF led to blends with very poor properties. 

Analogous behavior was observed by Oswald and co-workers (12) for blends of chlorinated polyethylene with a high chlorine content when the difference between the Tg s of the two components was greater than 30°C. In our case the values of ATg are about 45° (E13) and 34°C (E14) in regard to the homopolymer PVC. 

Blending of polymers is an attractive method of producing new materials with better properties. Blends of aliphatic polyesters, especially of poly(e-CL), have been investigated extensively and have been the subject of a recent review paper [170]. Poly(e-CL) has been reported to be miscible with several polymers such as PVC, chlorinated polyethylene, SAN, bisphenol A polycarbonate, random copolymers of Vdc and VC, Vdc and AN, and Vdc/VAc, etc. A single composition-dependent Tg was obtained in the blends of each of these polymers with poly(e-CL). This is of interest as a polymeric plasticizer in these polymers. Blends of PVC and poly(e-CL) with less than 50 wt % of poly(e-CL) were homogeneous and exhibited a single Tg. These blends were soft and pliable because the inherent crystallinity of poly(e-CL) was destroyed and PVC was plasticized... 

On the other hand, some mechanically compatible blends as well as some dispersed two-phase systems have made respectable inroads into the commercial scene. Many of these are blends of low-impact resins with high-impact elastomeric polymers examples are polystyrene/rubber, poly (styrene-co-acrylonitrile) /rubber, poly (methyl methacrylate) /rubber, poly (ethylene propylene)/propylene rubber, and bis-A polycarbonate/ ABS as well as blends of polyvinyl chloride with ABS or PMMA or chlorinated polyethylene. 

In situ polymerisation does not however guarantee homogeneous blends as two phase regions can exist within the polymer/polymer/monomer three component phase diagram. In the case of vinyl chloride polymerisation with solution chlorinated polyethylene, the vinyl chloride has limited solubility in both poly(vinyl chloride) and chlorinated polyethylene. The phase diagram has the form shown in Fig. 3 The limit of swelling of vinyl chloride in the chlorinated polyethylene is A and the highest concentration of PVC prepared by a one-shot polymerisation is B. 

Fig. 5. Plots of A, transmitted light intensity and B scattered light intensity (arbitrary units) against temperature for an initially homogeneous blend of an ethylene vinyl acetate copolymer with a chlorinated polyethylene. At the phase separation temperature there is a drop in transmitted intensity and a rise in scattered intensity...

Fig. 7a-c. Phase contrast microscope pictures of a blend of ethylene-vinyl acetate copolymer (40% vinyl acetate) with chlorinated polyethylene (43 % chlorine) before and after phase separation. Since both polymers are elastomers the mobility is quite high. The original pictures are coloured red and green. These black and white pictures have enhanced contrast to make the phase separation clear... 

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...

Strength of the specific interaction. An example of this is shown in Fig. 9 for blends of poly(butyl acrylate) with chlorinated polyethylene. In this case the blend requires a higher activation energy than its additivity value in the form of heat to allow chain movements. A review of this subject and of the relations between and chemical structure of blends has been given by Cowie For miscible blends many attempts have been made to correlate the with the blend composition as is frequently done with random copolymers. Several miscible blends studied by Hammer and Hichman and Ikeda exhibit a composition dependence of which can be described by the simple Fox relationship. 

A plot of tan 8 versus temperature gives a strong indication of blend homogeneity when a single T is detected or inhomogeneity when two T s are detected. An example of this method in studying blends of ethylene-vinyl acetate copolymers (45 wt.- % Ac) with chlorinated polyethelene (52 wt.- % Cl) at a constant frequency of 11 Hz is shown inFig, 10. Similar results obtained for blends ofchlorinated polyethylene (44 wt.-%Cl) with chlorinated polyethylene (62 wt.- % Cl) are shown in Fig. 11. 

Fig. 10. Plots of tan 5 against temperature for blends of ethylene-vinyl acetate copolymer (45 % vinyl acetate) with chlorinated polyethylene (52 % Cl) showing a single composition dependent glass transition temperature A EVA45 = 100 B EVA45 CPE - 20 80 C EVA45 CPE = 40 60 D EVA45 CPE = 80 20 E CPE = 100...

Fig. H. Plots of tan 8 against temperature for blends of chlorinated polyethylene (44 % Cl) with chlorinated polyethylene (66% Cl) 1 pure CPE (66% O) 2 87.0% 3 73.5% 4 50.0% 5 25.0% and 6 11.0% of CPE (66 % Cl) in CPE (44 % O) 7 pure CPE (44% Cl). The inset shows a plot of T against weight percent of the chlorinated polyethylene with the higher chlorine content, there is no marked deviation from linearity which is the expected result for systems with no specific interaction...

Fig. 15. DiiTerential thermal analysis traces of a blend of chlorinated polyethylene with poly(methyl methacrylate) obtained by heating at a rate of 10 °C/min. The blend was kept at the quoted temperatures for 10 min. and was quenched prior to scanning. The appearance of two T s after treatment at 190 C is indicative of phase separation at this temperature...

One example in this category is the case of one polymer in two stereoregular forms Other examples are of two polymers which are chemically very similar such as poly(methyl acrylate) with poly(vinyl acetate) A series of systems which have been studied in some detail are various mixtures of chlorine containing polymers. Blends of chlorinated PVC with PVC have been studied It has been suggested that at 65.2 % wt.- % chlorine they are miscible and at 67.5 wt.- % they are not. Chlorinated polyethylene with 45 wt.- % chlorine has also been found to be miscible with PVC In this case it was suggested that phase separation occurs on heating. 

Fig. 18. A plot of the minimum of the cloud point curve against chlorine content for blends of chlorinated polyethylene with ethylene-vinyl acetate copolymers having A (40 % vinyl acetate), B (45 % vinyl acetate). It is seen that the higher concentrations of interacting groups, CHCl or C=0, give a larger temperature range of miscibility...

Fig. 23. A part of the infra red spectra showing the carbonyl band absorption for (A) an ethylene-vinyl acetate copolymer and its blends with (B) 40 % and (Q 80% chlorinated polyethylene. The peak is shifted due to a specific interaction between the carbonyl and the methine hydrogen of chlorinated polyethylene. The shifted peaks are actually a combination of a shifted and an unshifted peak at different ratios...

Simulation studies have also been carried out on blends of chlorinated polyethylene with poly(butyl acrylate). The results are shown in Fig. 30. It was found in this case (in a similar way to the previous example) that with the value of X obtained from heat of mixing studies at 70 °C on oligomers (—94 atm) and with the value of Qjj necessary to match the spinodal to the minimum of the cloud point (—0.235 atm/K.) the resulting spinodal was very flat bottomed and lay outside the cloud point curve, an impossible situation. To match the spinodal to the cloud point curve a much smaller value of Xj2 (and correspondingly Qij) must be chosen. This discrepancy could have resulted from differences between the low molecular weight materials used for heat... 

Fig. 30. The experimental cloud point curve (dotted line) and simulated spinodals for blends of poly(butyl acrylate) with a chlorinated polyethylene. The initial value of X,2 = —94 atm obtained from heat of mixing data, and Che adjusted Q,2 = —0.235 atm K" give a curve which is too flat-bottomed (1). By adjusting X j using an appropriate Qjj) a closer fit can be obtained X2) Xj2 = -30Qi2 = -0.076 (3) Xjj = -10 Qjj = -0.026 (4) Xi2 = -1 Qij =. 0034 ...

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