The present invention relates to use of inexpensive semi-refined kappa carrageenan as a seaweed polysaccharide in preparation of tough, biodegradable films exhibiting improved performance over films obtained from refined kappa carrageenan. The formulation requires no gelling salt and the only other essential components of the film are glycerol and water, the former being used as plasticizer as reported in the prior art. The films can be recycled and reprocessed if required. The performance of the films can be further enhanced by incorporating polyvinyl alcohol that lends toughness and clarity as also natural rubber latex that imparts greater elasticity and barrier properties. Films of optimum composition can be pulse heat sealed immediately after casting and used for preparation of soft capsules and pouches. It is possible to store solvents and oils in the pouches. In view of the more eco-friendly processing of semi-refined kappa carrageenan compared to refined kappa carrageenan, films made with the former would also effectively be “greener”.