Cellulose is the material which is easily degraded by the action of radiation, and many studies have been carried out about radiation effect on it. However, as to the attempt replacing “ageing” in viscose rayon process with “depolymerization” by radiation, although a few studies, including the studies by one of the authors, were put into practice about ten years ago, less progress has been made since then.
At present, when, in some fields of radiation chemistry, time is getting ripe for industrial application, and large irradiators such as electron accelerators and cobalt-60 γ-ray sources can be gotten easily, it is considered that studies on the manufacture of low DP pulps by irradiation and the basic researches related to it are important problems from not only scientific, but industrial point of view, and for this reason we have made a start on these studies.
In almost all past studies about the radiation effect on cellulose, including ones by the authors, γ-rays were used as radiation, but, as it is expected from the industrial point of view that electron accelerator is promising, we have tried to make sure whether there are any differences between γ-rays and electron beams for the radiation effect on cellulose.
As to the depolymerization and the formation of oxidized groups (carbonyl-, and carboxyl- groups), for the irradiation of same dosage (absorbed dose) no difference between two radiations has been observed. From the consideration of the action of radiation on cellulose, that is, reaction processes consisting of the exitation of molecules, the formation of free radicals in them and the reaction of free radicals with other reactants, it is reasonable that there is no difference between the effect by two radiations.
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