Preface
This book describes fifty-one selected experiments in the chemistry of fibrous polymers and ancillary materials which have been designed primarily for undergraduate students in Technical Colleges, Polytechnics and Universities. Since the division between textiles and polymers is somewhat arbitrary, the book is aimed at students who are studying either of these technologies. The experiments vary in difficulty, and whereas the simpler ones could be performed by senior pupils in schools, some are of a research nature and are suitable for post-graduate courses in polymer or textile science. Since natural fibres are inherently variable and also require purification before use which may cause appreciable chemical modification, commercially they are subjected to more chemical tests than the synthetics. This is reflected in the relative numbers of experiments devoted to the two classes of fibres.
Many of the experiments are original and all have been performed many times in the authors’ laboratories to ensure that they will produce worth-while results. As a matter of policy, experimental procedures are given in detail to avoid the necessity for students to consult reference books which may not be readily available during practical periods. It is not intended, however, that these experiments should be regarded merely as exercises in handling apparatus and materials. It is important that they be read as a whole and the principles on which they are based are clearly understood before the commencement of practical work. Where possible, the references cited, which range from general articles to original papers, should be consulted and if appropriate the information may be incorporated in the laboratory report.
The authors wish to thank their colleagues Mr. J. T. Ball and Mr. D. E. Montgomery for helpful suggestions and Dr. I. Smith and Dr. J. G. Feinberg and the Shandon Scientific Company Ltd., for permission to use material contained in their book Paper and Thin Layer Chromatography and Electrophoresis. Finally, we would like to acknowledge the help of Mrs. C. Earland in the preparation of the manuscript and Mr. W. McDonald for assistance in checking many of the experiments.
General notes
The apparatus listed excludes common items which are normally found in a chemical laboratory. The list of materials, however, includes all chemicals required for the experiment except concentrated hydrochloric, nitric and sulphuric acids, 0-880 ammonia solution and solid sodium hydroxide. Where possible, the reagents used should be of ‘Analar’ grade. If a chemical is not manufactured in this grade or it is costly, ‘Laboratory Reagents’ (BDH) or ‘Laboratory Chemicals’ (M & B) may be used. Where ethyl alcohol is specified for an experiment, anhydrous (74° over proof) Industrial Methylated Spirits (IMS) is satisfactory.
If a chemical is excessively toxic or an operation requires special safety precautions, this is indicated in the text. Particular attention, however, should be paid to the following.
Sealed tubes containing acid hydrolysates must in no circumstances be handled when hot. The sealed tube should be placed upright in a small glass beaker contained in a stainless steel beaker of adequate height and the whole placed in the oven. It is permissible to open the oven during the heating operation, but the tubes must not be disturbed nor removed until the oven is cold.
Glass vacuum desiccators should be of heavy construction and obtained only from a reputable manufacturer. To avoid ‘sucking back’ due to variation of the water pressure, water pumps should be fitted with a non-return device or a filter-flask inserted in the line between the pump and the desiccator.
The accuracy to which quantities should be measured is indicated by the number of decimal places given, e.g. 2 g implies a mass between 1-5 and 2-5 g. 2-0 g a mass between 1-95 and 2-05 g and 2-00 g a mass between 1-995 and 2-005 g. Similarly, 25-0 ml should be within the range 24-95 and 25 05 ml. For volumetric analysis, grade B apparatus is sufficiently accurate. Small volumes, even for preparative work, are conveniently measured by graduated pipettes rather than by measuring cylinders.