Proceeding Articles

The principle of reactive sizing is discussed, and the variety of sizes which have been considered is reviewed.

The reactivity of tetradecyl ketene dieter towards water and model compounds for cellulose has been shown to be very low and the results suggest that very little ß -keto ester formation would be expected under normal papermaking conditions.

A study has also been made of the retention of C-14 labelled tetradecyl ketene dimer in laboratory handsheets, and of the degree of sizing which is induced. The results show that the dieter is present in the sheet predominantly in its unreacted form, but that a small percentage is present in a form which is not amenable to extraction by chloroform. This residual size exerts a considerable sizing effect, and the amount present in the sheet is related to the curing conditions used. The nature of the unextractable material has been studied by mild hydrolysis and the results are compatible with a low level of ß -keto ester formation. Comparisons have been made with C-14 labelled hexadecyl hexadecanoate, a compound of similar structure and physical characteristics but which is unable to undergo reaction with cellulose.

A study has also been made of the influence of aluminium sulphate on alkyl ketene dieter sizing. The retention of size in sheets made in the presence of aluminium sulphate is reduced, but not to a sufficiently low level to account for the loss in sizing which is observed. An explanation in terms of the inhibition of reaction of the dieter with cellulose as a result of adsorbed aluminium species is proposed.

According to Smoluchowski’s and Komagata’s theory, the electroosmotic and electrophoretic velocities vary with the depth of cell such that the distribution of velocities must be represented by a symmetrical parabola. However, in practical measurements of the electrophoretic velocities of sedimentary particles such as pulp fines and fillers, the distribution curve of velocities was found to be asymmetrical about the cell center. Thus use of the conventional method often gives rise to a serious error. The reasons for this are discussed and an improved method is proposed.

The time-dependent changes in zeta potentials (ZP) of clay and monodispersed polystyrene latex with added polyethyleneimine (PEI) or cationic polyacrylamide were investigated by the improved method. For instance, the ZP of clay, which was -42 mV originally, became +9 mV just after addition of PEI at a level of 0.1 % on clay, decreased rapidly at an initial stage, became -13 mV after
1 hr and finally reached -17mV. The rate of change in ZP varied widely with the degree of agitation, the addition level of polymer, the molecular weight and so on. The highest difference between initial and final ZP we have obtained hitherto is over 50mV. These phenomena must be closely related to the conformational change of polymers sorbed on solid surface and will offer important and fundamental information on how to use polymer additives in papermaking.

It has long been known that certain simple chemicals can either accelerate or retard the rate of refining of pulps. Based on surface adsorption and osmotic pressure considerations, a hypothesis is proposed to provide a rationale for the behavior of these chemicals. The validity of this theory is demonstrated by the prediction of the effectiveness of a colorless, photostable chemical as a new beating aid and the verification of its performance as an accelerator for the refining of both chemical and mechanical pulp as well as secondary fibers.

The adsorption of a cationic polyelectrolyte onto cellulose fibers in the presence of aluminum species was investigated. Solutions of either aluminum chloride or aluminum sulfate (alum) were used in the pH range 4.1-5.5. An apparatus was designed to simulate the mixing and turbulent conditions and to permit the short polyelectrolyte adsorption times found on typical paper machines. The effect of the aluminum species on the polymer adsorption depended on their concentration, counter-ion, pH, and time. From a knowledge of the equilibria of the aqueous aluminum species, it was possible to identify two distinct pH regions for aluminum and polyelectrolyte adsorption. At low pH, only soluble aluminum species were present and both aluminum salts reduced the rate and amount of polymer adsorption. At high pH the two aluminum salts formed distinctly different precipitates having very different effects upon polymer adsorption. The adsorption characteristics of each region are discussed and related to papermaking.

The carboxyl group content of a series of carboxymethylated pulps has been determined by a colloid titration method, by conductometric titration and by means of 14C-labelling and the values obtained by the different methods have been compared.

It is shown that, under certain experimental conditions, the colloid titration method can be used to determine the carboxyl group content of cellulose fibers.

This paper starts by considering the factors that determine fashions in fundamental scientific research in the field of physics and discusses the interaction of such research with industrial needs. It emphasises the importance of pure research both within industry and outside and suggests that this should be regarded by industrial accountants as an issue of ‘enlightened self interest’ for industry itself.

A living system however primitive, must include mechanisms for conservation as well as for variation of genetic information and for its adaptation to optimal phenotypic performance under given environmental conditions.

In order to maintain such a state of optimal performance the system has to metabolise steadily energy-rich material thereby remaining in a (meta-) stable ‘far from equilibrium’ position. If such material prerequisites are fulfilled ‘life’ should emerge inevitably as a ‘regularity among material events’ and such a regularity, if it exists, should be testable under laboratory conditions.

Virus replicases have been shown to provide efficient mechanisms for assembling de novo macromolecular RNA-templates from energy-rich monomeric precursors and for adapting them quickly to optimal self-reproductive performance. With the help of such systems the theory of molecular self-organisation (e.g. the quasi-species model) has been tested quantitatively. The experiments, in particular, have addressed the question “first template – first enzyme?” including adaptation of target and source function of the genotypes. A machine is described in which experiments on self-reproduction and translation can be carried out in a continuous and systematic way. Questions regarding the origin of life can thereby be scrutinised by experimental falsification.

The mechanical properties of fibrous composite materials will be reviewed. Such materials are made, either in order to realise in practice the properties of the fibres, or else in order to increase the toughness of a matrix. The mechanical principles governing the interaction of fibre and matrix will be sketched and up to date examples of the properties of both types of composite given.

The author deals with the complex relationships which can, or should, exist between fundamental and applied research, and discusses the ways in which healthy relationships can contribute significantly to a Nation’s economic growth. The author concludes that the traditional classification of research as either fundamental or applied may interfere with the development of the healthy relationships required. He suggests an alternative model, based upon distinctions between intrinsic and extrinsic motivation of the research activity.

Considering the very small amount of fundamental research, that is to say scientific investigation conducted with no particular objective, carried out in the past in the subject of pulp and paper, it is pointless to try to discuss its impact. If, however, the term is widened to include orientated research, then it becomes possible to elucidate its impact on breaks-through in pulping.

Numerous examples are presented to illustrate the relative importance of fundamental research in the achievement of technological breaks-through in such areas as outside chip storage, carbohydrate stabilising additives in alkaline cooking, delignification promoting additives in alkaline cooking, twostage sulphite cooking, oxygen bleaching, displacement bleaching, and steam drying.

The findings indicate that empirical experimentation as well as the artistic combination of existing knowledge, often from different disciplines, has been most effective in bringing about technological breaks-through. Fundamental research has also been quite effective when it has been directed towards the attainment of a specified objective. It seems to have been least effective when it has been primarily either explanatory, to set a recent finding in its proper background, or repetitive, to discover how a finding made elsewhere can be applied to local conditions.

All high quality fundamental research will give rise to new data for relevant system properties, and to new models representing the best available descriptions of the systems under consideration. This helps others to make future technological breaks-through, perhaps through empirical approaches, but often through the proper combination of knowledge from various fields.

The technical strength as well as the competitiveness of the industry will in the future, as in the past, be strongly dependent on the extent and effectiveness of the research which is undertaken. It is therefore essential for the future of the pulp and paper industry that R & D activity be maintained at a very high level.