Before being stored or thermally decompd. at =400 degrees C, waste PP (M, 12,500; crystn. deg., 53%) or LDPE (20,000; 42%) was dissolved in 25% (polymer wt. basis) 61-360 degrees C paraffin oil (M = 295 g/mol, I no. 5 gl(2)/100 g) in 15 min. at 140-190 and 120-170 degrees C, resp. The oil could be pressed out only at =7 MPa. The DSC thermograms showed the soaked polymers to be less thermally stable; the decompn. heat fell from 377 to 197 J/g PP Polymer-oil interactions examd in terms of Hildebrand's soly. and Flory-Huggins interaction parameters (58-102 degrees C.) with test solvents showed max. interactions to occur with low-M branched hydrocarbons.