Metals, ceramics and polymers

Book Reviews Metals, ceramics and polymers Oliver H. Wyatt and David Dew-Hughes Cambridge Univ. Press, London, 1974, 625 pp. £12 This book can be recommended as a reference book to any serious student of materials science. In one volume the authors have combined the at0mistic, microscopic and macroscopic approaches to materials and covered metals, ceramics, glasses and high polymers. The properties considered are mechanical, electrical and magnetic. Most of the standard proofs are given, often with an historical basis, which makes for interesting reading. There are many tables containing a great deal o f useful, factual information and the diagrams and illustrations are excellent. The authors have chosen a physical, engineering approach to their subject which will be welcomed by physicists and applied scientists, but may be less useful to the polymer chemist who might, with some justification, feel that he has not received his 'fair bite of the cherry'. Although polymers are discussed throughout the book, only 55 pages out of 625 a r e devoted exclusively to them. Inevitably there must be omissions in a book which attempts to cover as broad a field as this one. The authors realize this and argue that sensible selection of material is preferable to a wider coverage and superficiality. This is probably true, but it is arguable whether the complete omission of fabrication techniques in the section on polymers can be justified in view o f the importance that these techniques have in the choice of polymers in competition with other materials. Also the importance of correct design for plastics is not discussed, and there is nothing on environmental stress cracking. Spherulites are described briefly but there is no mention of the role of impurities in causing constitutional undercooling, although this is a feature which is common to the growth of spherulites in polymers and to cellular growth in impure metals. In the discussions on metals it is surprising that temper brittleness and blue brittleness are dismissed in one sentence. This is an ambitious book which largely achieves its objectives. It is written with style and humour, and each chapter ends with a selection of novel, often searching, questions. The price o f the hard-back version, £12, is not excessive in these inflationary times; the paper-back version, at just under £5, is excellent value for money. J.R. Atkinson

that with polymers the meaning o f 'crystal' has to be extended beyond the usage in simpler solids. It may be partly for this reason that the book seems a little old-fashioned; it is also because the subject matter is strangely out o f date. Excepting a slight sprinkling of the author's own papers, there are only nine references to work published after 1970, one on morphology, the rest on mechanical properties. Had work appearing even a few months later been included such erroneous information as e.g. that nitric acid attacks polyethylene in two separate stages (p 72) or that pressurecrystallized polyethylene contains fully-extended molecules (p 182) could have been corrected. Early work on inter- and intra-lamellar deformation was then also available. The chronological line has, nevertheless, to be drawn somewhere. It is the author's decisions on what to omit from established work which are the more disconcerting. Figure 2.21 is of an energetically vibrating dendrite to illustrate an early idea for the genesis of screw dislocations along re-entrant sector boundaries, but one which can hardly be of general application. Of the more extensive research which established that in non-planar lamellae a deviating sector boundary must lead to the observed overlaps, there is no mention. Nor is there the slightest indication o f how morphologically complicated systems other than polyethylene typically are. Most surprising o f all, however, is the treatment of spherulites - surely a major point of contact in the relation of properties to structure. Yet the main plank in our understanding o f their microstructure, the theory of impurity segregation advanced by Keith and Padden, is referred to only apropos dendritic crystallization from solution, a context where mass transport is the dominant diffusion process. In the chapter on melt crystallization the theory is not mentioned. Instead there is a dangerous intermingling o f 'dendritic' and 'spherulitic' and Keith and Padden's related work would only have been referred to in passing, as having made measurements on growth rates, had not a whole batch of references on this topic been mistakenly left out of the text. All things considered, it is undoubtedly useful to have all these topics brought together in a single volume, notwithstanding a certain awkwardness in the sequence of chapters. Indeed any book attempting to fill students' needs in polymer materials science at the present time has to be welcomed. For Professor Schultz's text, however, which in many ways is a disappointment, that welcome must, regrettably, be muled. D.C. Bassett

Polymer materials science

European Plastics Buyer's Guide 1975

J. M. Schultz

Prentice-Hall, Englewood Cliffs, N J, 1974, 511 pp. Not since Geil's 1963 Polymer Single Crystals has there been an attempt to embrace the entire field of polymeric physical structure and dependent properties in a single volume. That book, written in the heyday of morphological inquiry, was able to give a comprehensive account o f all textural studies then made plus the first rudimentary efforts to relate these to properties. To cover the same, now vastly more extensive, area today is a formidable task, but one which Professor Schultz has set himself in Polymer Materials Science. This is a postgraduate text comprising eleven chapters: Introduction dealing with chain conformations; Single crystals; Melt-crystallized polymers; Degree of crystallinity; Polymerization; Methods o f measuring molecular weight averages and stereoregularity; Mechanics of amorphous polymers; Time-dependent mechanical behaviour; Crystallization kinetics and mechanism; Electrical and electro-optical behaviour; and Mechanical behaviour o f semi-crystalline polymers. The student is helped by needing little background knowledge, by detailed explanations o f several investigative techniques and by the separation into appendixes of aspects of diffraction theory. There are also problems, some rather esoteric, attached to the earlier chapters. The very long second chapter is partly, the author explains, to convince us that 'in many ways the science o f polymeric materials is an extension of the science o f copper or lithium fluoride or steel.' There is no doubt that Professor Schultz's enthusiasm, which is always evident, knows few bounds whenever he is dealing with such familiar metallurgical topics as dislocations, on which there are 14 pages plus 3 in an appendix. Nowadays one would think that the pendulum of opinion has swung back and that it is appreciated

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POLYMER, 1975, Vol 16, April