Viscose rayon fabric samples were obtained from Misr Helwan Co., Helwan, Egypt. Stripes of viscose rayon fabrics (7 cm width) were extracted, for 30 minutes, with diethyl ether then with ethanol in a Soxhlet apparatus and finally were washed with distilled water. The extracted samples were then dried in a vacuum oven at 60˚C until constant weight and kept in a vacuum desciccator until used.

Methyl acrylate was obtained from B.D.H. Poole, GB, stabilized with 0.02% Methoxy phenol. Before use it was purified by fractional distillation under reduced pressure in presence of inert atmosphere.

Acrylonitrile was obtained from B.D.H. Chemicals Ltd., GB, stabilized with 0.005% Methoxy phenol. It was purified by fractional distillation under reduced pressure and inert atmosphere.

Acrylamide: m.p. 84.5˚C, was obtained from Merck Chemical Co., Germany, and was used without further purification.

Styrene was obtained from J. T. Baker Chem. Co. and was purified by shaking with 20% sodium hydroxide solution then washed with water and finally it was dried over anhydrous sodium sulfate overnight. It was purified by distillation under reduced pressure and the distillate was collected and kept in a desciccator until used. Fresh styrene portions were always used.

AnalaR methanol was obtained from Prolabo, Rhone, France. Pure Dimethyl formamide (DMF) was obtained from Veb-Laborchemie, Germany, and was used without further purification. AnalaR benzene was obtained from BDH, GB and was used without further purification.

The dye types used were: the direct dye 23 diamine fast scarlet 485, C.I. 2916 and the disperse dye Celliton pink FF3 and were obtained from BASF, Germany. The basic dye Sandocryl blue B-3 Gr, C.I. 41004 was obtained from Sandoz Germany.

Two solvent systems have been used in the present work namely methanol/water and DMF/water, on using acrylic acid monomers and methanol/benzene on using styrene monomer.

The graft yields (%) on grafting viscose rayon fabrics with different monomers namely, methyl acrylate, Acrylamide, Acrylonitrile and styrene, are shown in Figures 1-6.

On using methyl acrylate monomer the best graft yield was obtained on using 50% methanol in water as could be observed in Figure 1, while on using DMF/ water solvent mixture, extensive homopolymer formation occured as the percent water was increased up to 50% water, as could be observed in Figure 2. Good graft yields were obtained on increasing the water per cent above 50%.

In case of Acrylamide the graft yield (%) slightly decreased until 30% water, in both solvents was used, and the graft yield remained afterwards almost unchanged on increasing the water content in solvent used, as could be observed from the data shown in Figure 3 and Figure 4.

On using acrylonitrile monomer, in both solvent systems, the maximum graft yields of acrylonitrile onto viscose rayon were observed on using 30% - 40% water in solvent and remained after that almost the same on increasing the water content in the solvent, as could be observed in Figure 5.

In case of styrene monomer the best graft yields were obtained at methanol concentration 80% in benzene/methanol solvent as could be observed in the data shown in Figure 6.

On using mehyl acrylate monomer, the best graft yields (%) of methyl acrylate onto viscose rayon, using two solvent systems, were obtained at monomer concentrations greater than 7% as could be observed in Figure 7.

On using acrylamide, good graft yields (about 15%) were obtained on using 12% of monomer in methanol/water solvent mixture and on using about 15% monomer in DMF/water mixture, as could be observed in Figure 8.

In case of acrylonitrile monomer, the change of the graft yield on using different monomer concentrations, in the two solvent systems, is shown in Figure 9. Thus, on using 10% - 15% monomer in the solvent system, good grafting yields were obtained with low homopolymer formation. Higher homopolymer formation occurred on using higher monomer concentrations.

On using styrene monomer in grafting with viscose rayon in benzene/meth- anol solvent system (20:80), it could be observed that good grafting yields were obtained on using 10% - 12% monomer concentration, as shown in Figure 10.

On using methyl acrylate monomer the best graft yields were obtained at doses less than 1 kGy on using methanol-water solvent system (40:60) and 10% monomer concentration, as shown in Figure 11. On using DMF-water solvent system the best graft yields were obtained on using 7% monomer and about 3 kGys irradiation dose as could be observed in Figure 12.

On using acrylamide monomer, with the two solvents used, the best graft yields were obtained at irradiation doses greater than 7 kGys as shown in Figure 13.

In case of using acrylonitrile monomer, in both solvent systems, the best graft yields were obtained at irradiation doses greater than 8 kGys as could be observed from the data shown in Figure 14. Using higher irradiation doses did not significantly increase the graft yield.

On using styrene as monomer in benzene-methanol solvent system, the graft yields were found to increase linearly with irradiation dose up to 20 kGys, as

could be observed in Figure 15. The gamma irradiation dose used was preferred to be 16 kGy in order to reduce homopolymer formation.

From the foregoing results it was possible to choose the conditions that could be applied to prepare viscose rayon fabrics containing increasing graft yield. Thus, viscose rayon fabric samples in solvent system that can give the best graft yields together with 10% - 15% of monomer were subjected to increasing gamma irradiation doses. The physicochemical properties of the grafted samples were then determined.

Moisture absorption (%) or swelling (%) of viscose rayon fabrics grafted with methyl acrylate, acrylamide or acrylanitrile monomers in different solvent systems i.e. methanol/water or DMF/water were determined at different graft yields (%). The results are shown in Figures 16-19.

It could be observed that only minor changes occurred as the monomer graft yields (%) onto viscose rayon fabrics increased.

Moisture absorption and swelling of viscose rayon fabric samples grafted on styrene in benzene/methanol solvent (20-80) showed a gradual decrease as the graft yield (%) increased, as could be observed in Figure 19.

The tensile strength (%) and elongation at break of viscose rayon fabric samples grafted with different acrylic acid derivatives and with styrene were determined at different grafting yields. The results obtained are shown in Figures 20-23.

It could be observed both tensile strength and elongation at break values determined for the grafted samples decrease as the graft yields were increased up to 10% then remained almost the same as the graft yield was further increased. These results show that the tenacity of the viscose rayon fabrics increased with grafting.

In the present work, three types of dyes, a disperse dye; a direct dye and a basic dye were used with viscose rayon fabric samples grafted with acrylic acid derivatives and also with styrene. The change of the color strength of the grafted samples, due to dye uptake, with the corresponding graft yields has been studied.

Thus, on using a disperse dye with viscose rayon fabrics, grafted with methyl acrylate, the color strength of the dyed samples was rather low until the graft yield was about 7% then the color strength markedly increased on increasing the graft yields, as shown in Figure 24,a. In case of samples grafted with acrylamide or acrylonitrile no marked improvement in the dyeing ability was observed on increasing the graft yields, as could be observed in Figures 25,a and Figure 26,a. On the other hand, in case of viscose rayon fabrics grafted with styrene the color strength of the grafted samples markedly increased as the graft yield was increased (Figure 27,a).

On using the direct dye with viscose rayon fabrics grafted with methyl acrylate, acrylamide, acrylonitrile or styrene, the color strength of viscose rayon samples slightly increased on gradually increasing the graft yields up to about 10% and after that remained rather stable (Figures 24-27,b).

On using the basic dye with viscose rayon fabrics grafted with methyl acrylate, the color strength of the grafted samples was greatly improved on increasing the graft yields (Figure 24,c). In case of samples grafted with acrylamide the color strength of the dyed samples remained unaffected as the graft yields were increased (Figure 25,c). On using acrylonitrile monomer, the color strength of the

grafted samples was almost doubled on increasing the graft yield to 10% and then remained the same as the graft yields was further increased (Figure 26,c). Grafting of viscose rayon fabrics with styrene greatly improved the dyeing ability of the grafted samples as could be observed in Figure 27,c.

The crease recovery angle of viscose rayon fabrics grafted with methyl acrylate or acrylamide was measured for different samples and plotted against the corresponding grafting yields.

On using methyl acrylate or acrylamide in grafting to viscose rayon fabrics, the crease recovery angle significantly increased on increasing the graft yields up to about 3% then remained almost constant on further increasing the graft yields (Figure 28, Figure 29).

On using acrylonitrile the crease recovery angle showed a marked tendency to increase as the graft yield was increased, as could be observed in Figure 30. In case of viscose rayon fabrics grafted with styrene the crease recovery angle of the grafted samples was found to change sporadically around the value recorded for ungrafted samples (Figure 31).