UNPERTURBED CHARACTERISTICS OF ATACTIC POLYPROPYLENE: SOME NEW THETA SOLVENTS BASED ON ALIPHATIC KETONES

Solution properties of atactic polypropylene were studied in thermodynamically good solvents (toluene, n-butyl chloride and decalin) and in theta solvents (ethyl-n-butyl ketone, methyl-n-hexyl ketone, 1-nonanol and 2-ethylhexanol). Mark-Houwink-Sakurada relations within the temperature range between 15°C and 60°C, unperturbed dimensions Kθ = 1.62×10−3 at Tθ = 19.7°C in methyl-n-hexyl ketone (the Kθ and Tθ values for ethyl-n-butyl ketone are the same) and the temperature coefficient of unperturbed dimensions d ln r−2 0/dT = −2.44×10−3K−1 were established.