Three cellulose-styrene graft copolymers were prepared by heterogeneous mutual polymerization technique, initiated by gamma-rays a t a constant dose rate for different time intervals. The cellulose grafts were subjected to extraction with boiling benzene to remove the attendant homopolystyrene (PS), and then the cellulose backbones were degraded by acid hydrolysis. Each PS residue after hydrolysis has been separated with a thin layer chromatography (TLC) into two components: one involves some sugar residues due to hydrolysis at one of the chain ends, whereas the other does not. The former and latter components separated from a PS residue (PS-11) were denoted as PS-II(1) and PS-II(u), respectively. By making further use of TLC, the weight fraction of these components for each graft product has been determined, which allowed assessment of the per cent grafting due to true grafting. It is pointed out how difficult is the extraction of homopolymer from graft product.Number and weight average molecular weights, M, and M,, of PS-11, PS-II (1) and PS-I1 (u) have been determined by gel permeation chromatography, and others.The results indicated that M, found for PS-11 was much higher than that for PS produced in solution. Another finding was that M, for PS-II(l), i.e., truely grafted PS, was unexpectedly larger than that for PS-II(u), despite these polymers were formed both simultaneously inside the substrate. Further it was found that the molecular weight distribution of PS-I1 was appreciably broad, but this did result from a superposition of two fairly narrow distributions for PS-II(1) and PS-11 (u). The grafting frequency for a cellulose graft prepared at a total dose of 2 Mrads was assessed to be 0.03 by using necessary data obtained so far.
ZUSAMMENFASSUNG :Es wurden drei Cellulose-Styrol-Pfropfcopolymerisate durch heterogene, simultane Polymerisation hergestellt, die mit Gamma-Strahlen bei konshnter Dosisleistung, aber unterschiedlicher Bestrahlungsdauer gestartet wurden. Zuniichst wurden diese Copolymerisate einer Extraktion mit siedendem Benzol ausgesetzt, um das nebenbei gebildete Polystyrol (PS) zu beseitigen; dann wurde die gepfropfte Cellulose durch Hydrolyse mit Schwefelsaure vollig abgebaut. Durch Anwendung einer dunnschicht-chromatographischen Technik (TLC) wurde jeder PS-Ruck-
129T. TAGA and H. INAGAKI stand in zwei Komponenten aufgetrennt, wovon eine irgende&en Glukose-Rest an dem PS-Kettenende (PS-II(1)) triigt, wahrend die andere keinen solchen tragt (PS-I1 (u)) . Mit Hilfeder TLC wurde weiterhin das Gewichtsverhiiltnis der beiden Komponenten fur jedes Pfropfsystem bestimmt, welches die Abschatzung der auf echte Aufpfropfung zuruckzufuhrende Pfropfausbeute ermoglicht. Es wird darauf hingewiesen, wie schwer es ist, das innerhalb des Substrates gebildete Homopolymere &us dem Pfropfprodukt durch Extraktion vollkommen zu beseitigen.Fur die PS-Ruckstiinde, d.h. PS-11, PS-II(1) und PS-I1 (u), wurden die zahlenbzw. gewichtsmittleren Molekulargewichte (M, bzw. M,) durch Gel-Chromatographie und andere MeBmethod...
