Environmental Engineering Reference
In-Depth Information
linkages were mostly amorphous, with glass transition temperatures significantly
higher than their polyester analogs [103]. The furan-aromatic polyamides displayed
semi-crystalline behavior, with melting temperatures above 200°C [104]. In all
cases the decomposition temperature was above 300°C with some aromatic
polyamides exhibiting decomposition temperatures above 400°C, indicating good
thermal stability of these materials [67, 103, 104].
Polyester amides are an emerging class of materials with many attractive
features; they combine the excellent mechanical properties of polyamides and the
biodegradability of polyesters [106]. Recent investigations by Triki
et al.
used co-
polycondensation of 5,5′-(propane-2,2-diyl)-
bis
(furan-2-carboxylic acid) (BFA),
hexamethylene diamine, and ethane-1,2-diol to produce a series of furan-based
polyester amides with varying amounts of amines [107], and studied them using
DSC and TGA. The furan-based polymers were all amorphous and an increase in
glass transition temperature was observed as the amine content was increased
[107]. This underscores the versatility of furan-based monomers used in copo-
lymerization reactions, and identifies another method of tuning the physical
properties of furan-based polymers.
Despite relatively sparse interest in academic literature, furan-based polyamides
have seen growing industrial interest. Recent patents by Benecke
et al.
utilize
FDCA and aromatic diamines to produce curatives for polyureas, hybrid urethanes,
chain extenders for polyurethanes, and for reaction injection molding [108, 109].
In addition, companies have announced plans to bring FDCA-based polyamides
to markets such as carpets, textiles, and engineering plastics for automotive and
electronic applications [110].
5.3.7
Other Polymers
Polyurethanes can also be produced using furan-based diols, furan-based diisocy-
anates, or both for a completely furan-based polyurethane. Again, the majority of
this work has been advanced in Gandini's lab, and a series of papers outlines the
synthesis, kinetics, and property characterization of polyurethanes from furans
[111-115]. Their work explored the stability of the furan-based monomers, with
the notable finding that 2,5-furan diisocyanate is not stable [113]. In general,
furan diisocyanates are more reactive than their aromatic counterparts; however,
furan alcohols are less reactive than their aliphatic complements [73]. Thermal
analysis by DSC and TGA suggested that polyurethanes tend to crystallize and
exhibit moderate thermal stability, with onset of degradation temperatures at
around 200°C [114]. Their work also showed that it is possible to produce thermo-
plastic elastomers by incorporation of poly(tetramethylene oxide) glycol, PCL
glycol, or poly(butadiene) glycol as diol chain extenders [115]. Furan-based
thermoplastic elastomers showed lower moduli and thermal transitions compared
to their aromatic/aliphatic commercial counterparts, leaving only niche applications
for their use [115].
