Raman spectra are reported from single crystals of graphite and other graphite materials. Single crystals of graphite show one single line at 1575 em-I. For the other materials like stress-annealed pyrolitic graphite, commercial graphites, activated charcoal, lampblack, and vitreous carbon another line is detected at 1355 em-I. The Raman intensity of this band is inversely proportional to the crystallite size and is caused by a breakdown of the k-selection rule. The intensity of this band allows an estimate of the crystallite size in the surface layer of any carbon sample. Two in-plane force constants are calculated from the frequencies.

Polymer dissolution in solvents is an important area of interest in polymer science and engineering because of its many applications in industry such as microlithography, membrane science, plastics recycling, and drug delivery. Unlike nonpolymeric materials, polymers do not dissolve instantaneously, and the dissolution is controlled by either the disentanglement of the polymer chains or by the diffusion of the chains through a boundary layer adjacent to the polymer-solvent interface. This review provides a general overview of several aspects of the dissolution of amorphous polymers and is divided into four sections which highlight (1) experimentally observed dissolution phenomena and mechanisms reported to this date, (2) solubility behavior of polymers and their solvents, (3) models used to interpret and understand polymer dissolution, and (4) techniques used to characterize the dissolution process. q

The third edition of this well known textbook discusses the diverse physical states and associated properties of polymeric materials. The contents of the book have been conveniently divided into two general parts, 'Physical States of Polymers' and 'Characterization Techniques'. Written by seven of the leading figures in the polymer science community, this third edition has been thoroughly updated and expanded. As in the second edition, all of the chapters contain general introductory material and comprehensive literature citations designed to give newcomers to the field an appreciation of the subject and how it fits into the general context of polymer science. Containing numerous problem sets and worked examples this third edition provides enough core material for a one semester survey course at the advanced undergraduate or graduate level.

SynopsisThe ltaman spectra of collagen, gelatin, and elastin are presented. The Raman lines in the latter two spectra are assigned by deuterating the amide N-H groups in gelatin and by studying the superposition spectra of the constituent amino acids. Two lines appear a t 1271 and 1248 cm-1 in the spectra of collagen and gelatin that can be assigned to the amide I11 mode. Possibly, the appearance of two amide I11 lines is related to the biphasic nature of the tropocollagen molecule, i.e., proline-rich (nonpolar) and proline-poor (polar) regions distributed along the chain. The melting, or collagen-togelatin transition, in water-soluble calf skin collagen is studied and the 1248-cm-I amide I11 line is assigned to the 31 helical regions of the tropocollagen molecule.Elastin is thought to be mostly random and the Itaman spectrum confirms this assertion. Strong amide I and I11 lines appear a t 1668 and 1254 cm-', respectively, and only weak scattering is observed a t 938 cm-1. These features have been shown to be characteristic of the disordered conformation in proteins.

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