Swelling and Dissolution Mechanism of Poly(paraphenylene benzobisoxazole) Fibers in Poly Phosphoric Acid

摘要

Swelling and dissolution properties of (poly-paraphenylene benzobisoxazole) (PBO) fibers in (poly phosphoric acid) solutions were studied in this paper. The swelling and dissolution process was observed by light microscope and SEM. Depending on concentration of polyphosphoric acid solutions and swelling time, uniform or uneven swelling, disintegration swelling and dissolution were observed. In 5 and 10 % polyphosphoric acid containing solutions, the swelling of fibers were uniform type. In 15 and 20 % containing poly phosphoric acid solutions, the swelling of fibers were disintegration type. The uniform swelling would change to uneven swelling when the fiber immersed in solution for a few more minutes. The polylparaphenylene benzobisoxazole) fiber could dissolve totally in 5-20 % polyphosphoric acid/alcohol solution with different time. The swelling process could divide into constant speed dissolution and in constant speed dissolution. Polyphosphoric acid/alcohol solutions resulted in either dissolution or limited swelling depending on polyphosphoric acid concentration and swelling time.