Final answer:
Plasticisers make polymers more flexible by taking up space between the polymer chains and acting as lubricants.
Step-by-step explanation:
Plasticisers are additives that increase the plasticity of polymers, making them more flexible. They achieve this by taking up space between the polymer chains and acting as lubricants, allowing the chains to slide more easily over each other. Plasticisers lower the glass transition temperature (Tg) of the polymer, which is the temperature at which the polymer becomes more flexible and deformable.
For example, polyvinyl chloride (PVC) polymers are commonly plasticized to make materials like flexible vinyl garden hoses, waterbeds, shower curtains, raincoats, and upholstery. The plasticisers in PVC can migrate into the environment and cause concerns for human health.