Synthesis of difuran diesters from furfural, and their evaluation as plasticizers for polyvinyl chloride
The compounds 1,1-bis[ 5-(2-ethylhexyl, 2-octyl, hexyl, and butyl)carboxylate-2-furyl]ethane, and 5,5'-dihexylcarboxylate-2,2' bifuran were synthesized from furfural and characterized for their plasticizing abilities toward polyvinyl chloride (PVC) by dynamic mechanical thermal analyses (DMTA) with di-(2-ethylhexyl) phthalate (DOP) as the standard of reference. DMTA gave values for the depression of the glass-transition temperature (Tg) per mass fraction of plasticizer, and it also yielded a set of parameters, relative to those of DOP, which describe the compatability of the furan diesters with PVC. These values are compared to those of DOP and furan diesters incorporating only one furan ring in the molecular structure, which have previously been tested by this method. The difuran plasticizers are less efficient in lowering Tg than the monofuran plasticizers or DOP, with 1,1-bis[5-(2-octyl)carboxylate-2-furyl]ethane the least efficient and 1,1-bis(5-hexylcarbox- ylate-2-furyl)ethane the most effieient. On average the compatability toward PVC is better than that of DOP, and similar to that of analogous monofuran structures.