Thermosoftening polymers can be used to make plastic bottles and food packaging
1) the reaction to produce polymers uses a catalyst
why does the catalyst work for a long time before it needs replacing
2) thermosoftening polymers would not be suitable for packaging very hot food
explain why in terms of their properties and structure

1) Catalysts help to facilitate a reaction by lowering activation energy, but are not used up in this reaction. Eventually, however, they will need replacing as they become less efficient. 
2) Thermosoftening polymers only hold their rigid shape in cooler conditions, if hot food is placed in them the polymer will soften (effecively melt). This is because there is little attraction between the polymer chains in a themosoftening polymer so they move easily when heat is added.