Rita Dhawan , B. G. Karira

Abstract

The plantation grown Eucalyptus tereticornis is being widely used for the production of high-yield pulp component of newsprint furnishes. Present investigations have been carried out to optimize the proportions of high yield pulps, viz, Chemi-mechanical/Refiner mechanical pulps from E. tereticornis in admixture with high yield, viz, semi-chemical pulp from bagasse for making newsprint grade pulp furnishes. Results reveal that newsprint furnishes of satisfactory strength properties and improved brightness and opaci1y could be produced besides conserving the valuable Eucalyptus resources.

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Rita Dhawan , B. G. Karira , G. M. Mathur

Abstract

Investigations carried out at F.R.I. on the production of bleachable grade pulps suitable for cultural papers from some commonly occurring grass species of U.P. have been described. The results have been summarized in terms of chemical composition, fibre dimensions and physical strength properties of pulps under optimum conditions. The results of pilot plant investigations carried out on mixture of grasses suitable for papermaking have also been included.

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Rita Dhawan , B. G. Karira , Y. K. Sharma

Abstract

Results reported in this paper indicate that high alpha-cellulose pulps suitable for the manufacture of Filament Rayon and Tyrecord yarn can be produced from two species of tropica pines (P. pseudostrobus and P. greggi) by using acid -prehydrolyzed kraft process followed by multistage bleaching Dissolving-grade pulps were obtained in≈35-40% yield with ≈ 93--95% alpha cellulose and ≈86-88% Elrepho (I S.O.) brightness by using C/E/H/D or C/E/H/D/ E/D bleaching sequences.

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B. G. Karira , Rita Dhawan

Abstract

Chemical pulps (35-41% unbleached yield) consistent with good strength characteristics were produced from mustard straw using soda process. It was observed that mustard straw requires more drastic digestion conditions than rice straw and wheat straw. The data on proximate chemical composition and fibre dimensions of mustard straw is also recorded in this article.

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Rita Dhawan , B. G. Karira , S. V. Singh

Abstract

In this paper, papermaking qualities of three mangrove species viz. Heritiera Nitoralis, Bruquiera conjugata and Rhizephora mucronota of Andaman and Nicobar islands have been evaluated. The results indicate that unbleached kraft pulps(44.68 5 yield) suitable for wrapping papers could be obtained from all the three species. The unbleached pulps(kappa number 25±1) could be easily bleached to a brightness of 74±1(Elrepho) using CEH sequence and by applying 9.0% total chloride. The bleached craft from all the three species were found to possess satisfactory strength properties for making writing and printing papers.

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B. G. Karira , Rita Dhawan

Abstract

Pulp in good yield (≈ 60-78 per cent) could be produced from Mustard Straw using Hot Soda process. These pulps when admixed with a commercial bleached bamboo pulp had strength properties, brightness and opacity suitable for newsprint manufacture.

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B. G. Karira , Rita Dhawan

Abstract

Unbleached pulp in 47-52% yield suitable for wrapping paper could be produced from Elaeodendron glaucum by kraft (sulfate) process using 14-20% active alkali. The pulp having kappa number 25 was bleached by CEH sequence to give a pulp yield of 44% having 72% (Elrepho) brightness and satisfactory strength properties for the production of writing and printing papers.

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Y. K. Sharma , Rita Dhawan , B. G. Karira

Abstract

Laboratory experiments were carried out on the production of refiner mechanical pulps from kenaf sticks and chemical (Soda) pulp from kenaf base fibre. The blending of the pulps indicates that newsprint grade pulps could be produced from a furnish containing 80 per cent refiner mechanical pulps of kenaf sticks and 40 per cant chemical (Soda) pulp of kenaf best fibre. Our earier studies have indicatad that kenaf best fibre shows Poof bleaching response. Hence, in the experiments only unbleached pulp was used.

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Y. K. Sharma , Rita Dhawan , B. G. Karira

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Contrary to the long recognized superiority of wood sulphate pulps over wood soda pulps, it was observed that the yield and strength properties of soda and sulphate pulps from kenaf bark were approximately equivalent under identical cooking conditions. However,the two types of pulps differed in their response to bleaching. Soda pulp consumed higher bleaching chemical, but, showed lesser degradation than sulphate pulp, which is contrast consumed lesser bleaching chemical, but, showed considerable degradation under identical bleaching conditions.

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Y. K. Sharma , Rita Dhawan , B. G. Kar

Abstract

Laboratory scale experiments were carried out on the production or newsprint grade pulps from kenaf by chemi-mechanical pulping processes. Cold-soda, and alkaline sulphite processes were adopted. which could give pulps in high yield (≈7l-88%) having satisfactory strength properties, brightness and opacity. Blending of these pulps with a commercial bleached bamboo pulp further improved the strength properties and brightness.

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Rita Dhawan , B. G. Karira

Abstract

Laboratory scale experiments on the production of sulphate pulps for wrapping paper from Enterolobium timbouva were carried out. Proximate chemical analysis and fibre dimensions were also determined. The results indicate that Enterolobium timbouva is a suitable raw material for the production of wrapping paper.

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Y. K. Sharma , Rita Dhawan , B. G. Karira

Abstract

Airy Shaw while describing Gentianella glanduligera in 1943 stated that it was unknown in wild state. Recently, however, it has been collected in wild state in India and is being reduced to a varietal rank under Gentianella maddenii (Clarke) Airy Shaw. T. A. Rao collected a specimen in 1957 from Kumaun Hills and identified it as Gentiana recurvata Clarke; it was recorded by him as new for the North-West Himalaya. A critical study of this specimen revealed that it actually belonged to Gentianella glanduligera Airy Shaw having smaller stems and flowers than the Gentianella maddenii (Clarke) Airy Shaw; protologue and icon of the species confirmed the identity.

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Man Mohan Singh , R. N. Madan , Rita Dhawan , K. K. Karira , B. G. Karira

Abstract

Laboratory scale experiments were carried out on the production of wrapping, writing, printing and newsprint grade pulps from seven species by different pulping processes like sulphate, neutral sulphite, semi-chemical (N.S.S.C) and cold soda Unbleached pulps suitable for wrapping papers were obtained in satisfactory yield, and having satisfactory strength properties by using sulphate and (N.S.S.C.) process. For writing printing,paper the pulps were bleached by CEH sequence. Bleached pulps in satisfactory yield and good strength properties were obtained. Pulps in high yield could be obtained by cold soda process. Which when admixed with 28 bamboo sulphate pulp were considered to be suitable for newprint. Comparative suitability indice of wood, for wrapping and writing printing papers were calculated. From the results it Can be conciuded that all the seven species are suitable for wrapping, writing, printing and newsprint grade pulps.

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Rita Dhawan

Abstract

Dendrocalamus strictus was pulped by nitric acid process. Air-dry chips were cooked with nitric acid and sodium nitrite. The residual wood was extracted with dilute solution of caustic soda. The material was washed, disintegrated and screened. The yield of the pulps was determined. It was observed that by the addition of sodium nitrite upto a certain extent, delignification was enhanced. Pulps were analysed for Klason lignin content, pentosan content, nitrogen content, ash content and permonganate number. It was observed that the yield, Klason lignin content, pentosan content and permonganate number of pulps decrease with increase in concentration of nitric acid, cooking time and temperature.

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