Extensibility of paper and possibilities to improve it by chemical and mechanical means

The elongation of the typical wood fibres used in papermaking is in the range of 1 to 5%, so as for the paper made of such fibres These values seem to be extremely low in comparison with the common plastics such polyethylene, polypropylene and polyester in which elongation is measured in 100%-s magnitude. The low extensibility of paper is limiting use of paper in engineering and packaging applications despite on the relatively high strength. Extensibility of paper can be improved by manipulations with fibre structure, character of interfibre bonding, and structure of the fibre network. The question is whether these can be done simultaneously in the frame of the papermaking process? This work aims to provide a deep outlook on the extensibility of paper by reviewing the key factors affecting it. The combined approach for the improvement of extensibility of paper was suggested based on these considerations. Mentioned approach unites several methods including: mechanical treatment of fibres, addition of agar, compaction and low-restrain drying of paper. As a result of these treatments extensibility of paper can be increased up to 15% for uniform sheets and up to 30%-points for oriented paper.