Blocking Tendency
Cut two 60 mm 90 mm test pieces, put them together with PVC film facing inside. Hold the test pieces with two 60 mm x 60 mm smooth glass plstes aligning ome end of the gla with one of the short ends of the test pieces. Put a weight of 3 kg mass with a bottom area of 60 mm x 60 mm, and leave for 24 hours in 70 t 2 C thermostatic chamber. After 24 hours, take out the test pieces, remove the weight,and leave to cool at room temperature for i hour.