Thermo-Processable Polyimides with High Thermo-Oxidative Stability as Derived from Oxydiphthalic Anhydride and Bisphenol a Type Dianhydride

Abstract

Two series of homopolyimides based on oxydiphthalic anhydride and bisphenol A bisether-4-diphthalic anhydride were synthesized with 12 kinds of aromatic diamines. Several thermo-processable homopolyimides were the focus of further investigation. The structureproperty relationships of these homopolyimides were examined as functions of the glass transition temperature (T g ), melting point (T m ), thermal decomposition temperature (T d ), and meltflowability. The effects of the chemical and higher-order structures on these properties were discussed in this work to obtain an indication for the molecular design of high-performance thermoprocessable polyimides. A series of thermoplastic copolyimides were prepared to achieve higher T g and T d without sacrificing thermo-processability. The copolyimides investigated exhibited a comparable or lower melt viscosity, higher T g and T d , and higher long-term thermo-oxidative stability than those of ULTEM type polyimides. One of them exhibited a low melt viscosity (4700 poise at 400 • C), a high T g (224 • C), and excellent thermo-oxidative stability.

Poly(ester imide)s Possessing Low CTE and Low Water Absorption (II). Effect of Substituents

“…This can be interpreted in terms of suppressed internal rotation of the central hydroquinone moiety by some steric hindrance due to the present small substituents. If another more bulky substituent (such as phenyl group) were incorporated instead of the present methyl and methoxy groups, a decrease in T g would be caused as speculated from our previous data 35 that T g = 236 C for non-substituted ODPA/TPEQ and T g = 212 C for phenyl-substituted ODPA/PTPEQ where ODPA = oxydiphthalic anhydride, TPEQ = 1,4-bis(4-aminophenoxy)benzene, PTPEQ = 1,4-bis(4-aminophenoxy)-2-phenylbenzene. The present TAHQ series/4,4 0 -ODA systems also showed much higher CTE values ranging 47.1 to 51.2 ppm/K in addition to much lower tensile modulus than the rigid PEsI systems mentioned above, as predicted from their non-linear backbone structures but still lower than the values of common flexible PI systems (usually 60-80 ppm/K).…”

Melt processable homo- and copolyimides with high thermo-oxidative stability as derived from mixed thioetherdiphthalic anhydride isomers

“…The introduction of flexible linkage diamines significantly decreases the T g such as TPER and TPEQ contrary to the effect of more . This phenomenon can be attributed to the PIs with meta linkages disturb the intimate chain stacking necessary for intermolecular interaction [5]. As a result, the introduction of meta-linkages causes a significant decrease in T g .…”

“…For instance, commercial thermoplastic polyimide Ultem possesses excellent melt processability but its longterm service temperature is limited to lower than 170°C. Moreover, the thermoxidative stability of Ultem is also relatively poor because of the presence of thermally unstable isopropylidene groups in the polymer backbones [5]. Thermoplastic PIs are commonly applied in various industries because of the ease of processing, handling, and storage.…”

“…For example, 3,4'-oxydianiline (3,4'-ODA) has been proved to be a diamine with polyimide derivatives having better melt flowability than polymers from its isomer 4,4'-oxydianiline(4,4'-ODA) [16]. Other isomeric diamines, such as 1,3-bis(4-aminophenoxy) benzene (TPER) and 1,3-phenylenediamine (m-PDA), can also offer polyimides relatively lower melt viscosity than the corresponding para-isomers [5,17]. As a consequence, the processability of copolyimides is enhanced dramatically.…”

“…As a consequence, the processability of copolyimides is enhanced dramatically. The T g of these copolyimides generally range between that of homopolyimides from the two dianhydrides or diamines [5,16,18]. This principle makes it possible to predict the T g of copolyimides by appropriately selecting the structure and ratios of dianhydride and diamine component while obtaining improved melt flowability of PIs.…”