Daniel,
The answer is I haven't had any problems with static buildup, static charge or sparking. The swirl in the cyclone makes about 3 turns from top to bottm That's less than 10' of length of contact. . It's in a small section of the cyclone and the contact area of material with plastic is small (about 2" wide) so you have less contact of the product with the plastic than in the pipe. This is probably why I haven't had any problem with static. Also, we live in SC which is a humid area. I can't say for all parts of the country.
Ed