I've found most acrylic yarns break pretty easily. Usually I cut the yarn as opposed to "breaking" the yarn; I personally don't like the frizziness when you break the yarn.
Also, Clover has a yarn cutter pendant that I just LOVE! When I lost my first one, I went to store after store until I found another...lol...What's awesome about the pendant is well, it's a pendant...lol...Just find something sturdy to thread through the top of the pendant and wear it around your neck!
--The member formerly known as Demonica
"You must be the change you wish to see in the world."
- Mahatma Gandhi