modified PET using a single-screw extruder in the presence of pyromellitic dianhydride
But common polyimides, synthesized by pyromellitic dianhydride
and diaminodiphenyl ether, could easily form charge-transfer complex among monomeric units to enhance the intermolecular force, which makes the polyimide features high glass transition temperature ([T.sub.g]) and high melting temperature ([T.sub.m]).
Abstract Water-soluble hydroxyl functionalized hyperbranched polyester (WH-HP) resin was synthesized using pentaerythritol, pyromellitic dianhydride
, phthalic anhydride, and 1,1,1-tris(hydroxymethyl) propane.
(ODA) 99.9% Fluka; p-phenylenedianiline (p-PDA) 99.9% Acros; pyromellitic dianhydride
(PMDA) 99.2% Aldrich; tetraethoxysilane (TEOS) 99.6% Acros; 3-aminopropyltriehtoxysilane (APTES) 99% Aldrich; and dimethylacetamide (DMAc) 99.8% (water content less than 0.005%) Aldrich] were used as received.
The oligomer metal complex based on bisamic acid of pyromellitic dianhydride
has not attracted any attention.
Based on design of experiment (DOE) matrices, the influence of operating conditions on mechanical properties of molded samples were studied systematically for two kinds of m-PETs, namely, n-m-PET and m-m-PET synthesized using pentaerythritol (PENTA) and pyromellitic dianhydride
(PMDA) as modifying monomers, respectively.
Liu, "Infrared spectroscopic evidence of a direct addition reaction between palygorskite and pyromellitic dianhydride
," Applied Surface Science, vol.
1) used an entirely aliphatic ether as the diamine and reacted it with pyromellitic dianhydride
(PMDA), reducing the glass transition temperature significantly (51[degrees]C-75[degrees]C).
Such resins can be produced through chain extension/branching reactions with difunctional or polyfunctional reagents, as, for example, pyromellitic dianhydride
Both chain extenders used are tetra-functional, but have different specific reactivities: Pyromellitic dianhydride
(PMDA) reacts preferably with the hydroxyl end group of PET .
A recent example from our laboratories is the polyimide from 2,2'-bis(trifluoromethoxy) benzidine and pyromellitic dianhydride