Why do carbonated drinks seem to bubble more in plastic cups?

The properties and characteristics of a particular member of the plastics family, PET (polyethylene terephthalate), causes carbonated drinks to bubble more in plastic cups.

PET, a clear, strong
polymer, has unsurpassed gas and moisture barrier properties. Its
ability to contain carbon dioxide makes it the plastic, and the
material of choice for carbonated beverage containers.

PET containers have
no competition in retaining carbon dioxide, the gas responsible for the
effervescent, bubbling effect. The property that gives rise to a vast
number of bubbles is the unique barrier layers, which prevent the loss
of carbonation. The barrier layers serve to keep the container
airtight, which keeps the carbon dioxide from leaking out, and oxygen
from entering. This is why containers made from PET plastic keep
carbonated beverages colder, more flavorful, and fizzier.