Answer

3. Normal plastic packaging and bags are made from HDPE (high-density polyethylene), LDPE (low-density polyethylene), colouring and chalk. To make them degradable, all we have done is include trace amounts of a special additive. This additive causes the films to oxidise, meaning that the structure of the plastic is attacked by oxygen causing it to disintegrate more rapidly (i.e. it acts as a catalyst, speeding up a process that happens extremely slowly naturally).

Chalk (or calcium carbonate) is added as a natural, mineral modifier to the polyethylene during the film producing process in order to minimise the use of plastic, speed up the production process and improve the physical strength of the bag.