Sounds as if you experienced problems with vinyl plasticizers.

Mylar is good. Have also seen 'glassine' mentioned.
Some book dealers offer a clear protective jacket for an extra $1 or so, but I don't recall which. If I find info, will post.
Ken

There materials available on the net at some of the book binders supply house.  If you have a local library they can recommend a book cover that will do the job.  The newer ones (US) for school are stretchy and very nice.  I haven’t checkout there properties as of yet but need to.   
Twentieth Century Plastics used to have very good covers for photographs.  I don’t know if they are still in business.

Brodart Book Jacket Covers -info and source:
http://www.shopbrodart.com/site_pages/bjc/default.htm

Typical properties of cellulose acetate polymers include:

·         Good toughness

·         Deep gloss

·         High transparency

·         A feel that can be described as ‘natural’
 
Applications
Textiles and Fibres
Cellulose acetate fibres are used for textiles and clothing by many of the top designers in the world. Factors making this material suitable for this application include the fact that it is comfortable, breathable and absorbent. They can also be dyed in many different colours and combined with a range of other fibres such as rayon, cotton, wool, silk etc.
 

Cellulose acetate information source:  http://www.azom.com/details.asp?ArticleID=1461