Electrostatically charging a capacitor
To get the charge from the PVC into a capacitor, you could ground one side of the cap, and attach a wire to the other side of the cap. The end of the wire should preferably end in a fine point or collection of fine points, and you sweep this over the charged surface of the PVC to collect what charge you can. 

If you use a smaller capacitor you will tend to get more voltage, but even a small capactior (e.g., 100pF) is probably only going to get as far as a couple of volts, even off a PVC surface charged to 10's of kV, because the capacitance of the PVC surface probably isn't even 0.1pF.