[PHP] Wordrap - just long words

Is there a way of getting the wordwrap() function to just wrap the idividual words (un separated by spaces) and not sentences that have spaces in them.

I.E.

Turning
‘This is a very long woooooooooooooooooooooord’

Into
‘This is a very long
woooooooooooooo
oooooooord’

Not
‘This is a very
long wooooooooo
ooooooooooooord’

(the examples split every 15 chars)

Any help would be appreciated
Thanks