Poly crystalline and amorphous

H. P. Klug, L. E. Alexander, X-Ray Diffraction Procedures for Poly crystalline and Amorphous Materials, Wiley, New York, NY, 1974. 

Chris G. Van de Walle, Hydrogen Interactions with Poly crystalline and Amorphous Silicon-Theory... 

Owing to high viscosity, broad molecular weight distribution, existence of poly-crystalline and amorphous material, the liquid crystalline nature of thermotropic polym.ers is usually established through a combination of these methods. 

C. J. Carman Earlier in your talk you showed the carbon Ti data and NOEF for partially crystalline and amorphous poly-isoprenes. Was this a natural rubber which had been allowed to crystallize to different degrees or was this a synthetic rubber ... 

First introduced to polymer chemistry by Schaefer and collaborators, CP-MAS spectroscopy has already yielded interesting results in both stractural and dynamic studies. The comparison of spectra in solution and in bulk permits identification of frozen conformations, distinction between spectra of crystalline and amorphous phases and measurement of the rate of several eonformational transitions. For example, the C spectrum of the poly(phenylene oxide), 74, in solution consists of five signals while the CP-MAS spectrum displays six. In the solid state the resonance of the aromatic CH appears split into two components. The phenomenon is attributed to the forbidden rotation of the benzene ring around the O. .. O axis, which makes the two carbon atoms indicated with an asterisk no longer equivalent. 

The separation of the crystalline and amorphous phases into their respective spectra has been carried out for a number of polymers including polyethylene terephthalateS6), polystyrene 57), poly(vinyl chloride)58), polyethylene 59,60) nylon61), polypropylene 62), and poly(vinylidene flouride)63). 

The investigation of the 300 MHz spectrum of poly(3-methyl-l -butene) indicates that the conclusions drawn by previous workers (2—4) concerning the structures of the crystalline and amorphous polymers are essentially correct the crystalline polymer being almost entirely of the 1,3-structure and the amorphous polymer being a mixture of both 1,2- and 1,3-structures. Further, it has indicated that this method is useful for analysis of the composition of the polymer. Quantitative composition determination, however, has not been carried out, since it is felt that the accuracy of the previous estimates utilizing near infrared spectroscopy were satisfactory. 

The scaling of the lamellar thickness with degree of polymerization of the crystalline and amorphous blocks was investigated for PEO-poly(ferf-butyl methacrylate) (PEO-PtBMA) diblocks using DSC and SAXS by Unger et al. (1991). The non-equilibrium exponents obtained immediately after bulk crystallization were found to be different to those from equilibrium results extrapolated... 

The discussion of the influence of the interphase need not be limited to just linear polyethylenes. Interphases of several nm have been reported in polyesters and poly-hydroxy alkanoates. One major difference between the interphase of a flexible polymer like polyethylene and semi-flexible polymers like PET, PEN and PBT is the absence of regular chain folding in the latter materials. The interphase in these semi-flexible polymers is often defined as the rigid amorphous phase (or rigid amorphous fraction, RAF) existing between the crystalline and amorphous phases. The presence of the interphase is more easily discerned in these semi-flexible polymers containing phenylene groups, such as polyesters. 

It is very likely that during the polymerization under the strict control of the monomer crystal lattice, a strain energy caused by molecular movements accumulates on the reacting crystals resulting in the endothermal formation of polymer crystals. The enthalpy difference between the crystalline and amorphous polymers (3.1 kcal/mol) corresponds to the heat of crystallization of as-polymerized poly-DSP crystals. 

The cell efficiency of a single crystalline Si solar cell reaches 18- 0 % in the mass production line. The poly crystalline and cast Si solar cell shows 15-18% on average. The cell efficiency of amorphous Si solar cells (a-Si) is 8-9 %. Silicon solar cell generates electric power of direct current with about 1 V, a few combinations of which are suitable to apply to water-electrolysis. Therefore, if Si solar cell is combined with SPE, the system efficiency will be 10 % in practical use. This value is the highest among the systems which produce hydrogen with use of renewable energies as will be described here in-below. 

Fig. 1.12 Wide-angle X-ray scattering pattern for poly s-capralactone obtained at room temperature using a transmission X-ray diffractometer. The inset illustrates how the total scattering (points) can be decomposed into crystalline (full lines) and amorphous (broken line) components. The dotted line represents the sum of the crystalline and amorphous components.

Evidently the crystallites in poly (4-methylpent-l-ene) are permeable to oxygen. The crystalline and amorphous forms of the polymer have nearly the same densities and oxidation patterns at 100°C (see Fig. 2) and consume tenfold more oxygen than the linear polyethylene. 

Vega AJ, English AD (1980) Multiple-pulse nuclear magnetic resonance of solid polymers. Polymer motion in crystalline and amorphous poly(tetrafluoroethylene). Macromolecules, 13 1635... 

Similar procedures have been used by several workers (Halasa et al., 1982) to hydrogenate poly(l,4-butadiene-co-1,2-butadiene) diblocks (Halasa, 1985) and poly(l,4-butadiene-co-l,4-isoprene-co-1,4-butadiene) triblocks. Hydrogenation of these diblock and triblock copolymers forms thermoplastic elastomers with crystalline and amorphous segments. All these materials exhibit crystallinity, glass transition, solubility, and dynamic mechanical loss spectra different from those of their unsaturated counterparts. 

Figure 10-3. Specific heat capacity Cp at constant pressure of partially crystalline (— — —) and amorphous (—0 — 0—) poly[oxy-(2,6-dimethyl)-l,4-phenylene]. Tcryst denotes the beginning of recrystallization, Tg is the glass transition temperature, and Tm is the melting temperature (after F. R. Karasz, H. E. Bair, and J. M. O. Reilly).

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