If higher amounts of glutaraldehyde crosslinker are used with PVA, then this will lead to branching. Branching, as you know, reduces crystalllinity. So before deducing any thing from XRD analysis, we have to know how much aldehyde was used & if the polymer did not contain any "crystalline" impurity.

Please see the reference below:

http://onlinelibrary.wiley.com/doi/10.1002/app.29263/abstract

Thank you very much Mr.NIzar , pls resend the the link provided previously. Because ,not able to downlad the attachment.

Yes to add to Nizar Matar, as soon as you crosslink, you would be disrupting the possible formation of crystallinity.  Thus the more cross-linked, the less the possibility of any crystallisation.