Effect Of Thermal Oxidation On The Properties Of Chemical Refined Paer Pupl:

Khaled Abdel-azim Mahmoud Tamim

This research aims to study the effect of treating refined paper pulp(high α- cellulose) with different concentrations of sodium hydroxide inpresence of 0.5 % zinc chloride on aging of treated paper pulp in order toproduce more resisting paper to aging to be used in documents that shouldvirtually have the longest life possible.For this purpose bleached karft wood pulp (American origin) thatcontain 87 % α-cellulose, 9.5 % pentosan, 0.3 % ash, < 20 ppm silica and0.6 % lignin, with 12o SR was used.Enough amount of pulp was treated each time with differentconcentrations of sodium hydroxide solution (2, 6, 10, 14and 18 %), then thesamples were washed with water till neutralization. Thereafter 10 % aceticacid solution was used to remove any traces of sodium hydroxide, and thenwashed with water till neutrality. After that each pulp was beaten alone till50o SR. Enough amount of each sample of paper was prepared for carryingout the study.To study the effect of accelerated thermal aging on samples, eachsample was exposed to thermal aging at 100o C for a period of 24-96hours, then the mechanical, chemical and physical properties of the sampleswere studied (for both untreated and treated samples) to find out the mostsuitable concentrations that can be used to get the ultimate aging-resistingpapers. The properties studied were elongation, breaking length, burst factor,X-ray crystallinity and degree of polymerization.SUMMARYviiFor untreated samples (blank samples) that weren’t treatedthermally or with sodium hydroxide solution, it found that the elongationdecreased with the increase of exposing time to heat and as the sameresults for the breaking length, burst factor, while both X-ray crystallinityand degree of polymerization found to be increased by increasing ofexposure time to heat. On the other hand, in case of treated samples withdifferent concentrations of sodium hydroxide, it was found that theelongation, the breaking length, burst factor, X-ray crystallinity anddegree of polymerization decreased with increasing concentrations ofsodium hydroxide solution from 2-18 %. For instance, elongationdecreased about 22 % which the sample treated 18 % sodium hydroxideand breaking length increased from 2908 m (for untreated sample) to7397 m after treating with 2 % sodium hydroxide, this can be due to thatthe cellulose treated with this concentration lead to removal of very smallcellulosic chains and in accordance the breaking length increases. Burstfactor was found to be largely affected, as it loses 84 % of its value incase of treating by 18 % sodium hydroxide. While X-ray crystallinityloses 25 % from its original value and degree of polymerization loses45 % from its original value in case of treating by 18 % sodiumhydroxide.For the samples treated by 2 % sodium hydroxide then thermallytreated at 100o C for time intervals 24-96 hours, it was found that theelongation, the breaking length and burst factor decreased to differentdegree as a result of increasing the heating time intervals; while X-raycrystallinity and degree of polymerization increase as a result of heattreatment up to 24 hours then decrease thereafter.