วัตถุดิบทดแทน (Alternative raw material)
[1] http://www.vcharkarn.com/varticle/38233
[2] http://www.pvc.org/en/p/what-is-pvc
[3] http://www.matbase.com/material/polymers/engineering/pet-bottle-grade/properties
[4] http://www.recoup.org/shop/product_documents/99.pdf