k.k. chawla, ,fibrous materials (1998) cambridge university press 0 521 57079 4 293pp, £55

BOOK REVIEWS

Thermal Data for Natural and Synthetic FuelsS. Gaur and T.B. ReadMarcel Dekker Inc, 1998280pp, $150, ISBN 0 8247 0070 8

Reviewed by R. Kandiyoti (Imperial College, UK)

For engineers and researchers requiring nominal pyrolysisweight loss parameters for about 100 fuels and relatedmaterials, this neatly turned out little volume may wellprove helpful. Under the attractive and somewhat moregeneral title than appears warranted, thermogravimetric anddifferential thermal analysis data have been presented forsamples ranging from cellulose and lignin to pumpkin seedand several well-recognized US coals, with a few liquidfuels thrown in. The emphasis is mainly on biomass typematerials. Some of the tested materials appear a littlespecialized: ’ spinach stem cell chloroplast’ , pistachio nut,paper (25 % cotton mix), RDF (Thief River Falls), RDF(Teledyne).

Apart from weight loss and DTA data, the authors havepresented several well-written background chapters. Theoverview of thermal analysis methods has been con® ned tothermogravimetry and differential thermal analysis, withdifferential scanning calorimetry and thermomechanicalanalysis receiving honourable mentions. In these few shortchapters of text, the reader enters the timeless world ofthermogravimetry, where well de® ned kinetic expressionsappear to characterize the pyrolytic behaviour of virtuallyany fuel. The authors neatly show how TGA/DTA derivedkinetic data can be processed in terms of sound elementaryphysical chemistry.

Clearly TGA and DTA are well established methods andthey have their uses; these instruments are convenient forcontinuous recording of weight loss and energy import/export as a function of time; they usually give goodrepeatability. They have also proved their utility indetermining combustion reactivities of chars and accurateboiling point distributions of heavy liquids Ð particularlywhen small amounts of sample are available. Its manufac-turers (catalogue number cited), must have noted thereverence with which the particular make of the apparatusused in preparing the data has been described withsatisfaction. Occasionally, one ® nds mentioned that activa-tion energies reported in the literature for various fuels mayrange widely, e.g. from 50-250 kJ/mole for cellulose. Butthe reader is quickly put at his ease with possible reasons fornon-standard results. The underlying message seems to be:’ Stick with our method and you will be all right’ .

However, TGA/DTA systems do have their limitations.Reading these pages, one might well be left wondering whyso much effort has been expended in developing fuelcharacterization methods during the past several decades.Some of the limitations of GTA/DTA equipment arise fromlower available heating rates [1±100°C min 1] thanthose encountered in real-life reactors such as ¯ uidizedbeds [104 ±105 °C sec 1]; problems also arise from thestacking of particles on TGA-pans. These characteristics of

TGA/DTA equipment do not normally allow extrapolatingpyrolysis data to either more realistic bench scale experi-ments, nor to pilot or commercial scale pyrolysis andgasi® cation systems. In particular, the text appears to ignoredif® culties Ð read impossibility Ð of reconciling kineticconstants calculated from TGA derived data to morerealistic systems where particles behave in segregatedfashion. The underlying problem remains: sample weightloss as well as kinetic constants calculated from pyrolysisdata obtained in these instruments are speci® c to theparticular con® guration of the instruments themselves. Thatin itself may have its uses: for example it allows calculatingrelative reactivities of a set of fuels that may be of particularinterest. Indeed, it appears possible to re-con® gure the textto bring out the value of the TGA/DTA instruments.

As it stands, however, the book presents itself as acollection of TGA/DTA derived pyrolysis data on a ® xedmenu of samples, some of which appeared relatively rare,and several well written chapters on well known basicequations. At the price, I think one would have expected theauthors to make a more robust effort to attract thespecialized reader.

Fibrous MaterialsK.K. ChawlaCambridge University Press, 1998293pp, £55, ISBN 0 521 57079 4

Reviewed by Ken Jones (DuPont, UK)

I commend the author for a highly comprehensive book on® bre materials. It covers all the complexity of the different® bre types in an interesting and easy read. The book couldbe used as a textbook on ® bres covering the educationalspectrum from high school through university to an initialintroduction to the industry. Details are included of thenatural ® bres such as wool, cotton, rayon and silk andhighlight their unique structure and properties. It dealsbrie¯ y also with the problems associated with their use,including the effect of environmental factors such ashumidity, UV radiation, temperature, and micro-organism.The author covers the development of all the various typesof synthetic ® bres currently on the market including detailsof their manufacturing routes, properties and their strengths.The materials used to produce polymeric ® bres are classi® edas either condensation polymers or addition polymers. Inthis case there is suf® cient information on all aspects ofmaterial production and processing to give the reader a goodinsight into the routes required to give the ® bres their uniqueproperties to meet marked needs.

The application/property matrix is well de® ned andexplained. It covers their use in textiles, industrial applica-tions, body armour and ® re resistance. The skill andunderstanding that has now been attained to develophighly oriented ® bres is explained, as well as the speci® cproperties including moisture penetration, antistatic andconductive properties that can be achieved by modi® cation

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to the physical structure of the ® bre. Material structure andits in¯ uence on ® bre property is explained and its role inde® ning the tensile properties, including recovery, isdeveloped, covering applications from elastomers to highmodulus ® bres. The introduction to production of metallic® bre and the in¯ uence of crystal structure on properties isboth enlightening and constructive. It deals with themanufacture, the in¯ uence of metal type on properties andend use in suf® cient detail to give the reader an excellentgrasp of requirements. Similarly, suf® cient detail is given onthe various type of important ceramic ® bres currently in use.

The in¯ uence of both chemical and crystal structure onproperties is very well documented. Natural ceramic ® bressuch as asbestos and basalt are mentioned. Consideration isgiven also to amorphous glassy materials which form good® brous structures such as silica-based glass ® bres. Detailedinformation is given on the various processes used in theirmanufacture. The formation of single crystal ® bre isexplained and bene® ts reviewed. The physical properties areconsidered and reviewed against structure and processingtechniques used in manufacture. Detailed information onmarkets and general application of the various glass ® bretypes is given. The sol-gel process used to manufacture

glass ® bre as well as information on techniques used to makeoptical glass ® bre is detailed. In the latter case, the need andimportance of high purity is stressed and the methods toachieve it explained. In this system the important element isthe difference in the refractive index between the core andthe cladding, with the former being higher.

A variety of optical ® bre systems are described and theirproperty relationshipgiven. Methods and techniques used tomanufacture carbon ® bre and their relationship to propertiesare explained. The relative importance of the carbon crystalstructure in developing ® bre strength and high modulus, andthe importance of its anisotropic nature is detailed. The roleand in¯ uence on the starting material on properties isexplained. Important application markets are identi® ed andproduct speci® cation requirements given. Very usefulproperty relationships have been included which can beused to de® ne requirements. Certain carbon ® bres can haveextremely high thermal conductivity (four times that ofcopper) and techniques used for production is given. Thelast two chapters are devoted to the measurement ofproperties and statistical treatment of ® bre strength. Theauthor has included a very comprehensive bibliographic listwhich can be referred to for additional information.

989BOOK REVIEWS

Trans IChemE, Vol 76, Part A, November 1998