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.
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.
catalysts are not used up in reactions
thermosoftening polymers have weak intermolecular forces which quickly makes them melt and break away from bonds holding them together.
Catalysts remain effective for a long time because they are not consumed in the reaction and can facilitate it repeatedly. However, thermosoftening polymers are unsuitable for hot food because they soften and lose structure when exposed to high temperatures.
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