Is it possible that there is a chance after ovulation for fertilization to occur? Does it not just disintegrate if its not fertilized with 12-24 hrs?

Possible. Nobody knows the exact answer but the egg can still be around for up to 24 hours after ovulation. After that unlikely.
Yes. You may still get pregnant several days after ovulation. In fact, i recommend that if you are attempting pregnancy, that you have intercourse every other day, starting on day 10, through day 20. The egg takes several days to pass through the tubes and the uterus.