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

Abstract

Abstract.A series of homo-and copolyimides based on mixed thioetherdiphthalic anhydride isomers (mixed-TDPA) were synthesized with several kinds of aromatic diamines. The properties of these polyimides were characterized by glass transition temperature (Tg), thermal decomposition temperature, and melt processability. A series of copolyimides were prepared to achieve high Tg concurrently with melt processability by means of selecting appropriate diamines and their composition in the copolyimides. As a result, we obtained rheological information for a series of polyimide resins as a function of temperature, time and shear rate. It is found that the processability (e.g., melt viscosity of polyimides) and ultimate product properties (e.g., Tg of polyimides) can be systematically varied by changing the variety and composition of the aromatic diamines. It has been demonstrated that the incorporation of meta-or flexible diamines improve the melt processability of polyimides significantly. Meanwhile, Tg of copolyimides from dual-diamines can be predicted and regulated. Accordingly, copolyimides from 1,3-phenylenediamine (m-PDA) and 3,4'-oxydianiline (3,4'-ODA) were obtained with higher Tg and lower melt viscosity. Such correlations of chemical structures and rheological behavior provide the necessary database for tailor-making new polyimide systems with desirable processability and physical properties.

Rigid High Temperature Heat-Shrinkable Polyimide Tubes with Functionality as Reducer Couplings

“…The PIHSTs prepared with copolyimides of 6FDA/ODA + BAB are labeled as PIHST04, PIHST05, PIHST06, PIHST07 and PIHST08, whose molar ratios of ODA:BAB were 0.15:0.85, 0.30:0.70, 0.50:0.50, 0.70:0.30 and 0.88:0.12, respectively. Just like other copolyimides reported, the m/n ratios of ODA:BAB for the shape memory copolyimides are also similar to the specific molar ratios in the synthesis process, as the reactant monomers are not detected in the products44454647.…”

Phenylethynyl-terminated imide oligomers derived from thioetherdiphthalic anhydride isomers with decreased melt viscosities

“…The asymmetrical structure of 3,4 0 -TDPA and 3,3 0 -TDPA in the polymer backbones could dramatically reduce the polymer chain-to-chain interactions. 29,34,35 Furthermore, decreasing the molecular weights of the oligomers led to an apparent drop in the minimum melt viscosity, and at the same time, it provided a broader processing window as expected. 17,26,33 Isothermal viscosity measurements at 280 C were also conducted to test the melt stability.…”

Facile control of high temperature shape memory polymers

“…It has been proved that the fitting of T g s to Fox Equation is mainly caused by the similarity in molecular structures of polymer components of the copolymers . As manifested in Figure , both BAB and BAPB molecules contain two ether linkages connecting benzene rings, and thus there is similarity in the molecular structures of BPADA/BAB and BPADA/BAPB.…”

“…Copolymerization is an efficient and convenient method to obtain polymers with expected properties, and copolyimides have attracted attentions from various fields . The shape memory copolyimides of BPADA/BAB‐BAPB were synthesized with two‐step polycondensation process by employing BPADA as dianhydride and the combination of BAB and BAPB as diamines, and the sythesis process is shown in Figure .…”