Composition dependence poly blends

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... 

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. 

The above mentioned scaffolds were made completely of the ceramic materials. Other potential materials which could be used to fabricate a novel construct for the repair of ciitical-sized bone defects is a novel material made of biodegradable polymer reinforced with ceramics particles. The properties of such a composite depend on 1) properties of the polymer used for the matrix and properties of the ceramics used for the reinforcement, 2) composition of the composite (i.e. content of ceramic particles) and 3) size, shape and arrangement of the particles in the matrix. Several polymer-composite composites have been used for scaffolds fabrication including polylactide (PLA) and polycaprolacton (PCL) reinforced with calcium phosphate (CaP) micro and nanoparticles. Authors proposed a novel composite material by blending copolymer -Poly(L-lactide-co-D,E-lactide) (PLDLLA) a copolymer with a ceramic - Tri-Calcium Phosphate... 

Blends of poly(trimethylene terephthalate) (PTT) and PEN are miscible in the amorphous state over a wide range of eompositions. This is evidenced by a single, composition-dependent glass transition temperature (7 ). The variation of the Tg with composition can be predicted by the Gordon-Taylor equation, with the fitting parameter being 0.57. 

Polystyrene (PS) and poly(vinylmethylether)(PVME) are mutually compatible over the entire range of composition, and their blends have thus often been chosen for experimental studies on the phase separation dynamics of binary polymer mixtures. The subsequent discussion depends heavily on the data re-... 

Experiments on temporally forcing of phase separation were performed using mixtures of poly(vinyl methyl ether) (PVME) and anthracene-labeled polystyrene (PSA). The phase diagram of this PSA/PVME blend is illustrated in Figure 1 together with the composition dependence of its glass transition... 

Figures 2.6 and 2.7 illustrate such differences in the cases of polystyrene/ SBR poly blends and SBR random copolymers, respectively (Tobolsky, 1960, pp. 79-82) the overall S/B ratio is approximately the same in each. Figure 2.6 shows that both transitions depend on composition.

FT-Raman spectra were determined for atactic PS, poly(2,6-dimethyl-l,4-phenylene ether) (PPE) and then-blends. Composition-dependent spectral variations of the blends were analysed using generalised 2-D correlation spectroscopy to study the conformational changes and blend interactions. The 2D synchronous correlation analysis was able to discriminate between the bands of PS and those of PPE, and was able to detect bands that were not readily identifiable in ID spectra. The main chain conformation of PS undergoes a drastic change on blending with PPE (57). 

In this paper, an attempt is made to relate the mechanical (tensile) properties of a family of related polyblends to the state of compatibility of the blend. The prototype compatible blend studied is that of poly (2,6-dimethy1-1, 4-phenylene oxide)(PPO) and polystyrene (PS). Evidence for the compatibility of PPO and PS is substantial and is reviewed elsewhere (5). Films molded from blends of PPO and PS are optically clear and exhibit a single composition dependent glass transition temperature (Tg). 

The composition dependence of the relative molecular mass for entanglement has been studied in the context of viscoelasticity for example polystyrene (PS) and poly(xylenyl ether) (PXE) are fully miscible but have very different values of Me, 19100 for PS and 4300 for PXE. Measurements of the plateau modulus of mixtures suggested that a simple harmonic mean blending law was followed (Prest and Porter 1972). 

Figure 4.25. (a) The mutual diffusion coefficient in the miscible polymer blend poly(vinyl chloride)-polycaprolactone (PVC-PCL) at 91 °C, as measured by x-ray microanalysis in the scanning electron microscope (Jones et al. 1986). The solid line is a fit assuming that the mutual diffusion coefficient is given by equation (4.4.11), with the composition dependence of the tracer diffusion coefficient of the PCL given by a combination of equations (4.4.9) and (4.4.10). The tracer diffusion coefficient of the PVC is assumed to be small in comparison, (b) The calculated profile of diffusion between pure PVC and pure PCL, on the basis of the concentration dependence of the mutual diffusion coefficient shown in (a). The reduced length u — where the... 

Phase separated blends of poly(vinyl alcohol) [PVA] and poly(vinyl acetate) [PVAc] were studied and evidence of intra-molecular and inter-molecular specific interactions was reported to depend on blend composition [ 59 ]. Blends with high PVA content were reported to have large intra-molecular specific interactions while blends with a high PVAc content showed inter-molecular interactions. The... 

In this communication we present the results of an FTIR study of the blend system poly(bis-phenol A-carbonate) (PC) - PCL. This is a complex blend system which contains two crystallizable polymers with large differences in the crystalline melting points (T ) and glass transition temperatures (Tg). Cruz, et al.have demonstrated from thermal analysis and dynamic mechanical testing that blends of PC and PCL have a single Tg which is dependent only on the composition of the blend and conclude that the amorphous phase is miscible. These authors also concluded that the miscible amorphous phase results primarily from physical rather than chemical interactions between the polymers. 

For noncompatibilized PP/PC blends, the compositional dependence of the heat deflection temperature (HDT), modulus, yield and frachue strength showed a negative deviation from additivity. Addition of a compatibilizer improved the blend performance. Excellent mechanical properties, impact strength, HDT, moldability, and solvent and chemical resistance have been claimed for compatibilized blends containing 5-95 wt.% of either PP or PC. The best overall effects were observed using poly(propylene-g-styrene/acrylonitrile). 

Poly(8-caprolactone) (M =40,000) was blended with a series of ethylene terephthalate-PCL copolyesters of different composition 13 the polyesters were presumably random copolymers [123]. The copolymers, containing 18-87% caprolactone units, were prepared by copolymerisation of ethylene terephtha-late and 8-caprolactone molecular weights were not quoted but intrinsic viscosities of the copolymers were between 0.84 dl g" and 1.99 dl g" The pure copolymers exhibited composition-dependent glass-transition temperatures from -65 °C (87 wt % 8-caprolactone) to 33 °C (18 wt % 8-caprolactone). 

Figure 4.39 shows the data obtained by DSC for poly(N-vinyl-2-pyrrolidone) (PVP)-poly(vinyl chloride) (PVC) blends [58]. It can be seen that each blend has a single glass transition temperature which varies with blend composition. The appearance of one composition-dependent Tg reveals its single-phase nature, i.e. PVP is miscible with PVC over the entire composition... 

The above example concerns an isotope blend where the interaction is very weak. An example of a polymer blend where miscibility is due to specific interactions is the well-known deuterated polystyrene/poly(vinyl methyl ether) (dPS/PVME) blend. Here the complete theory as outlined above was applied and the composition dependence ofx,/, and/ was derived from the composition dependence of/sc determined by SANS (Figure 13) A... 

Y. Ren, T. Murakami, T. Nishioka, K. Nakashima, I. Noda, Y. OzaJd. Two-dimensional near-infrared correlation spectroscopy studies of compatible polymer blends composition-dependent spectral variations of blends of atactic polystyrene and poly- (2, 6-dimethyl-l, 4-phenylene tihe,r).J Phys Chem B 104 679, 2000. 

Recently, polymer blends, especially miscible blends and polymer alloys, are being widely studied and developed for industrial materials [26]. In an immiscible blend of two polymers that has two separate Tg two tan d peaks may appear that correspond to the Tg of each polymer [I]. On the other hand, a miscible blend has only one tan d peak, whose location depends on the components in the blend. Figure 25 shows a plot by Margaritis and Kalfoglou [27] of the temperature dependence of and E" for a miscible blend composed of poly(vinyl chloride) and epoxidized polybutadiene (EPB). The E shifts to lower temperatures when the EPB component is increased. A single E" peak appears, and this peak shifts among the peaks of the component blends according to the composition of the blend. 

Ren, Y, T. Murakami, and T. Nishioka, Two-Dimensional Near-Infrared Correlation Spectroscopy Studies of Compatible Polymer Blends Composition-Dependent Spectral Variations of Blends of Atactic Polystyrene and Poly(2,6-Dimethyl-l,4-Phenylene Ether). J. Phys. Chem. B, 2000. 164 679 90. 

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