Poly crystalline composites with

In addition the quality, crystallinity, and microstmcture for a particular composition plays an important role. For example, single-crystal NagSi46 has nearly two orders of magnitude lower p than a poly crystalline specimen with the same composition [107, 137]. It is therefore equally important to investigate new synthetic tools in order to assess the transport properties of different compositions (cf. Chap. 3). 

Figure 8. Comparison of true charge transfer coefficients q for chloride (a) and bromide (b) estimated from plasma electroreflectance data (smooth poly crystalline Pt) with X and Y values in solutions of the same anionic composition (c - chloride, d - bromide, dispersed electro-deposited platinum). The area between two curves (a, b) corresponds to unavoidable scatter (boundaries present to limiting versions of q recalculation). Dashed fragments (a) correspond to the region of lower accuracy, as compared to the overall potential region. Reprinted from Refs. 195 (a, b) and 194 (c, d). Copyright (1990) and (1969), respectively, with permission of Nauka Publ.

The simple model given above does not take account of the facts that industrial refractories are poly crystalline, usually non-uniform in composition, and operate in temperature gradients, both horizontal and vertical. Changes in the coiTosion of multicomponent refractories will also occur when there is a change in the nature of tire phase in contact with the conoding liquid for example in Ca0-Mg0-Al203-Cf203 refractories which contain several phases. 

The first article may be a polymer composition with a COC as basic material. Suitable low crystallinity polymers to fabricate the second article include COCs and blends of COCs with poly(methyl pentene), other polyolefins, and styrenics. 

The word polyallomer is derived from the Greek words alios, meros. and poly. Alios means oilier and denotes a differentiation from the normal. The word meros means parts and the prefix poly is added to show that these materials are polymeric. Since allomerism is defined as a constancy of crystalline form with a variation in chemical composition, the polyallomers are examples of allomerism in polymer chemistry. 

Mixtures of poly(vinylidene fluoride) with poly (methyl methacrylate) and with poly (ethyl methacrylate) form compatible blends. As evidence of compatibility, single glass transition temperatures are observed for the mixtures, and transparency is observed over a broad range of composition. These criteria, in combination, are acceptable evidence for true molecular intermixing (1, 19). These systems are particularly interesting in view of Bohns (1) review, in which he concludes that a compatible mixture of one crystalline polymer with any other polymer is unlikely except in the remotely possible case of mixed crystal formation. In the present case, the crystalline PVdF is effectively dissolved into the amorphous methacrylate polymer melt, and the dissolved, now amorphous, PVdF behaves as a plasticizer for the glassy methacrylate polymers. 

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... 

QuasicrystaUine phases form at compositions close to the related crystalline phases. When solidified, the resultant strucmre has icosahedra threaded by a network of wedge disclinations, having resisted reconstruction into crystalline units with three-dimensional translational periodicity. The most well-known examples of quasicrystals are inorganic phases from the ternary intermetallic systems Al-Li-Cu, Al-Pd-Mn, Zn-Mg-Ln, Al-Ni-Co, Al-Cu-Co, and Al-Mn-Pd. In 2007, certain blends of polyisoprene, polystyrene, and poly(2-vinylpyridine) were found to form star-shaped copolymers that assemble into the first known organic quasicrystals (Hayashida et al., 2007). 

Equations (6.32) to (6.34) have been successful in describing the PVT dependencies of PE [Simha and Jain, 1978 Jain and Simha, 1979a, b] and more recently of the poly( -caprolactam) (PA-6) [Utracki, 2009a,b,c,e]. In the latter case, owing to great variability of the crystalline content with T, P, and composition, the Pastine idea of additivity of the crystalline and noncrystalline domains has been applied. 

SMP based on miscible blends of semicrystalline polymer/amorphous polymer was reported by the Mather research group, which included semicrystalline polymer/amorphous polymer such as polylactide (PLA)/poly vinylacetate (PVAc) blend [21,22], poly(vinylidene fluoride) (PVDF)/PVAc blend [23], and PVDF/polymethyl methacrylate (PMMA) blend [23]. These polymer blends are completely miscible at all compositions with a single, sharp glass transition temperature, while crystallization of PLA or PVDF is partially maintained and the degree of crystallinity, which controls the rubbery stiffness and the elasticity, can be tuned by the blend ratios. Tg of the blends are the critical temperatures for triggering shape recovery, while the crystalline phase of the semicrystalline PLA and PVDF serves well as a physical cross-linking site for elastic deformation above Tg, while still below T ,. 

Crystallites may also be considered to act as reinforcing fillers. For example, the rubbery modulus of poly(vinyl chloride) was shown by lobst and Manson (1970,1972,1974) to be increased by an increase in crystallinity calculated moduli in the rubbery state agreed well with values predicted by equation (12.9). Halpin and Kardos (1972) have recently applied Tsai-Halpin composite theory to crystalline polymers with considerable success, and Kardos et al (1972) have used in situ crystallization of an organic filler to prepare and characterize a model composite system. More recently, the concept of so-called molecular composites —based on highly crystalline polymeric fibers arranged in a matrix of the same polymer—has stimulated a high level of experimental and theoretical interest (Halpin, 1975 Linden-meyer, 1975). 

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