Solving our plastic bottle problem 3. Some alternatives to plastic Natural polymers that have not been chemically modified are exempt from the directive. Any plastics created from modified natural polymers, or fossil or synthetic feedstocks, are effectively banned. The winners here will be a range of new sustainable materials that are not considered chemically modified. These include regenerated cellulose, which is used to create viscose, lyocell and cellulosic films. The most abundant biopolymer on our planet, regenerated cellulose is used to create a strong, transparent and completely biodegradable film or sheet that is largely impermeable to oils and greases. A long-used food packaging material before the introduction of oil-based plastics, cellulose is back.