Synthesis And Barrier Properties Of PA66/12I, PA66/12T And PA66/12N Copolyamides

Barrier materials were more and more used along with social progress. Barrier polymers played a very important role in packaging nowadays because of their excellent properties, such as low specific gravity, convenient process ability, unbreakable, etc. Now, production of plastic packaging materials in China could not meet the requirements of international market competition in high barrier performance, so development of high barrier packaging materials would show obvious social and economic benefits. Nylon was widely used as a kind of barrier polymers. Barrier nylon was mainly used in automotive plastic tanks and barrier packaging industry. Generally, nylon had a good barrier property to non-polar solvents, while its barrier property still needed to be improved. In these studies, three series of semi-aromatic copolyamides PA1212/12I, PA1212/12T and PA1212/12N were synthesized. And the barrier properties, crystalline morphology, melting and degradation behavior of these three series of copolyamides were studied. The main results of this work were summarized as following:1. Three series of semi-aromatic copolyamides were synthesized by melting polycondensation.2. The barrier properties of these three series of copolyamides were studied. And the relationship between semi-aromatic nylon salt contents and barrier properties was studied. The relationship between types of semi-aromatic nylon salt and barrier properties was also studied. The results showed that the water vapor barrier properties increased with the amount of semi-aromatic nylon salt increasing. But compared with Nylon 66, the water vapor barrier properties of PA66/12I copolymer decreased when the added amount of semi-aromatic nylon salts was less than 40%, and the water vapor barrier properties of PA66/12T copolymer decreased when the added amount of semi-aromatic nylon salts was 10%. By comparison of water vapor barrier properties of three series of copolyamides, the water vapor barrier properties of PA66/12N copolymers were better than those of PA66/12T copolymers, and the water vapor barrier properties of PA66/12T copolymers were better than those of PA66/12I copolymers, when the added amount of semi-aromatic nylon salts was the same.3. The crystalline morphology, melting and degradation behavior of the semi-aromatic copolyamides were studied by DSC, XRD and TG. The melting peaks of copolymers moved to lower temperature first, then moved to higher direction with the increase of the amount of semi-aromatic salt content. The crystallization peaks of copolymers were not obvious when PA66 salts and PA12T salts (or PA12N salts) addition was 60:40 and 40:60. The degradation temperature increased with the amount of semi-aromatic nylon salts increasing.