Poly-1-oxy-2-phenyltrimethylene as studied by 1H pulsed low resolution NMR: a possible oxygen scavenger

• Published in: European polymer journal Vol. 35; no. 4; pp. 681 - 690
• Main Authors: Capitani, D, Segre, A.L, Barsacchi, M, Pentimalli, M
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.1999
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/S0014-3057(98)00158-X

Aromatic polymers can adsorb a large amount of oxygen on their aromatic rings. In semicrystalline aromatic polymers, the amount of adsorbed oxygen is much larger in the amorphous phase than in the crystalline counterpart. As a consequence, fully amorphous aromatic polymers are more suitable as oxygen scavengers than semicrystalline polymers. A pulsed low resolution 1H-NMR relaxation study on semicrystalline and fully amorphous poly-1-oxy-2-phenyltrimethylene (St–CO), deuteriated and not deuteriated on the backbone, is reported. T 1 relaxation values were measured at 30 and 57 MHz and compared with the values of two aromatic polymers previously studied, syndiotactic polystyrene (s-PS) and polyphenyleneoxide (PPO), both patented as oxygen scavengers. For all these polymers, using a set of equations, at each temperature, the amount of adsorbed oxygen was calculated. Very short T 1 values are observed at the low temperature point of PPO which is the best oxygen scavenger at low temperature, while St–CO adsorbs oxygen efficiently at room temperature. Thus, St–CO might be suitable to be used as an oxygen scavenger. In St–CO, a 1H T 1 ρ relaxation study on the rotating frame has also been performed. In the atactic copolymer, in the temperature range 150–160 K, a sharp transition was observed only in the presence of oxygen. In agreement with a previously given interpretation for analogous data, the observed transition might be related to low frequency motions present in low molecular weight components.