Selective hydrogenation of butadiene–styrene copolymers using a Ziegler–Natta type catalyst 2. Thermal properties

• Published in: European polymer journal Vol. 39; no. 6; pp. 1151 - 1167
• Main Authors: Escobar Barrios, Vladimir A, Petit, Alain, Pla, Fernand, Herrera Nájera, Rafael
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2003; Elsevier
• Subjects: Anionic block and random copolymers; Applied sciences; Chemical modifications; Chemical reactions and properties; Exact sciences and technology; Homogeneous hydrogenation; Organic polymers; Physicochemistry of polymers; Thermal properties; Thermal properties; Homogeneous hydrogenation; Anionic block and random copolymers; Butadiene copolymer; Catalytic reaction; Ziegler Natta catalyst; Regioselectivity; SBS; Butadiene derivative copolymer; Crystallinity; Experimental study; Hydrogenation; Structure composition relationship; Thermal stability; Random copolymer; Triblock copolymer; Chemical modification; Diblock copolymer; Unsaturated copolymer; Styrene copolymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/S0014-3057(02)00380-4

Three types of butadiene–styrene copolymers, diblock, triblock and random, were partially hydrogenated in their elastomeric units in order to determine the influence of hydrogenation extent on their thermal properties. The hydrogenation reactions were carried out using a Ziegler–Natta type catalyst and the extent of hydrogenation was evaluated by FTIR spectroscopic technique. The percentage of crystallinity was determined by differential scanning calorimetry (DSC), considering the low density polyethylene (LDPE) as reference since the saturation of elastomeric units with low content of 1,2-vinyl bonds gives a structure which resembles to LDPE, thus semi-crystalline polymers were obtained. On the other hand, the glass transition temperature ( T g) for the hydrogenated and non-hydrogenated copolymers as well as their heat of fusion, were also determined by DSC. An equation to evaluate the T g of partially hydrogenated random copolymers is proposed considering both the saturated and unsaturated fractions. The thermo-oxidative behaviour of certain hydrogenated and non-hydrogenated copolymers was evaluated by thermogravimetric analyses (TGA). The results obtained by TGA suggest that a minimum saturation level is necessary in order to improve the thermo-oxidative resistance of the polymers.