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ABSTRACT:A sample of chemical cotton (pure cellulose) has been grafted with acrylonitrile (AN), methyl methacrylate (MMA) and acrylamide (AAd) using MnH ions complexed with pyrophosphate in acid aqueous solution (pH=l.7) at 30°C. The conversion of monomer to polymer and the add-on to the substrate weight have maxima at an MnH concentration of about 0.50 mM and at a monomer/substrate ratio of about 2: I. Under optimal conditions the grafting efficiency is about 95% for AN and 65-75% for MMA. For AAd the conversion is low (8-IO%) and the grafting efficiency < 50%. These results have been interpreted as due to the low accessibility of the cotton cellulose (high crystallinity)'and the known properties of the three monomers. The homopolymer formed of MMA is interpreted as largely due to chain transfer to monomer and that of AAd as mainly due to initiation by MnH oxidation of monomer. Alkaline hydrolysis of ANgrafted cotton fibers gives a water retention value of 65-70 g g-1 .KEY WORDS Cotton Cellulose / Graft Copolymerization / Vinyl Monomers / Manganic Ion Initiator / Alkaline Hydrolysis / Water Retention / A new redox system for initiation of graft copolymerization of vinyl monomers to polysaccharides has been developed in our laboratories and first applied to starch. 1 The initiator is Mn 3 + ions in complex form in aqueous solution of pH 1.5 to 2 at about 30°C. This initiator is also active with cellulose as substrate. 2 Both bleached cellulosic fibers from wood (lignin-free) and waterswelling cellulose ethers of low degree of substitution are efficiently grafted with this initiator. 3 using all known initiation methods appeared at the same time. 5 The purpose of this paper is to describe grafting experiments with a very pure cotton cellulose as substrate and complexed Mn 3 + ions in aqueous acid solution as initiator. Based on the results, the mechanism of initiation is discussed in detail, considering our recent studies of metal ion oxidation of model compounds. 6

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Kompozyty polimerowe podatne na (bio)degradacjêStreszczenie -Na podstawie przegl¹du literatury (obejmuj¹cej publikacje a¿ do roku 2007 w³¹cznie) scharakteryzowano metody wytwarzania i niektóre w³aoeciwooeci u¿ytkowe mieszanin polimer syntetyczny/skrobia ze szczególnym uwzglêdnieniem mo¿liwooeci zwiêkszenia podatnooeci na biodegradacjê tego rodzaju uk³adów na podstawie polietylenu. W ramach badañ w³asnych okreoelono wp³yw wprowadzenia 10 % samego epoksydowanego kauczuku naturalnego (ENR) lub mieszaniny ENR z nadtlenkiem dikumylu (DCP) na biodegradacjê otrzymywanych metod¹ reaktywnego wyt³aczania kompozytów polietylenu lub polipropylenu zawieraj¹cych 60 % skrobi plastyfikowanej gliceryn¹ (SG). Stwierdzono, ¿e po 36 miesi¹cach przebywania próbek w glebie ubytek masy wynosi 30-35 % w zale¿nooeci od sk³adu kompozytu, przy czym ubytek ten zwi¹zany jest g³ównie z degradacj¹ fazy skrobiowej. Zmiany w³aoeciwooeci mechanicznych podczas rozci¹gania w toku trwaj¹cego do 36 miesiêcy testu glebowego sugeruj¹ tak¿e istotne zmiany struktury matrycy poliolefinowej, zw³aszcza sieciowanie PE i degradacjê PP. Na zaobserwowane zmiany istotny wp³yw wywiera obecnooeae dodatków (ENR, DCP), czas degradacji oraz odczyn gleby. S³owa kluczowe: biodegradacja w glebie, polietylen, polipropylen, plastyfikowana skrobia, kompozyt, w³aoeciwooeci mechaniczne. POLYMER COMPOSITES SUSCEPTIBLE TO BIODEGRADATIONSummary -On the basis of the literature data (review covering publications up to 2007) the methods of preparation and some useful properties of the systems synthetic polymer/starch were characterized. Especially the possibility to increase the susceptibility to degradation of the systems based on polyethylene/starch with compatibilizers or polyesters (polycaprolactone)/starch made by reactive extrusion has been discussed. The results of own research concerned the effect of the introduction of 10 % of epoxidized natural rubber (ENR) or the mixture of ENR with dicumyl peroxide (DCP) into the composites of polyethylene or polypropylene (produced by reactive extrusion), containing 60 % of starch plastified with glycerol (SG), on their biodegradation (Table 1). It was found that after 36-month hold time of the samples in the soil, the weight loss was in the range 30-35 % dependently on the composition (Fig. 1) but of course the weight loss concerned mainly the starch phase (Table 1). Changes of tensile properties during 36-month soil test ( Fig. 2 and 3) suggest also significant changes in the structure of polyolefin matrix, especially PE crosslinking and PP degradation. These observed changes are strongly dependent on the presence of additives (ENR, DCP), degradation time and soil reaction.

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