Unfortunately, I can answer this from experience. My children were 4 and 6 at the time of my divorce. Prior to my divorce, the stress both I and their father were feeling was quite overwhelming.
Given that both their father and I seldom had "good" converstaions, my children could (even at a this young of an age) could feel the tension of our household. They both seemed to shy away when their father and I were in the same room.
After our divorce, my children changed dramatically. The loving relationship that I had once known, prior to the fighting, returned.
As a teacher, I also see the impact of family stress on my students. Grades will drop, friendships will break up, and the interactions between the child and parent dwindle.
These students feel as though they have enough problems of their own simply dealing with growing up. Any stresses added because of parental stress simply seems to much for them to bear.
As for any research on the subject, check out the links below.