Properties Of Copolyimides Research Articles

Synthesis and properties of copolyimides based on ternary dianhydrides and dibasic diamines

A series of copolyimides were prepared by thermal imidization of polyamide acids derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,3′,3,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, p-phenylenediamine and 4,4′-oxydialinine commonly used for the production of commercial polyimides. The flexible copolyimide films characterized by ultra-low coefficient of thermal expansion were obtained and characterized by FTIR, WAXD, TG, DMA, TMA, FE-SEM and tensile properties measurement. The results showed that three copolyimides remained semi-crystalline and exhibited high glass transition temperature, high thermal stability, and great ultimate strength.

Structural effect of monomer type on properties of copolyimides and copolyimide-silica hybrid materials

In this work, the effect of two different diamine monomers, containing phosphine oxide, on thermal, mechanical and morphological properties of copolyimides and their hybrid materials was investigated. Gas separation properties of the synthesized copolyimides were also analysed. Two different diamine monomers with phosphine oxide were bis(3-aminophenyl) phenylphosphine oxide (BAPPO) and bis(3-aminophenoxy-4-phenyl) phenylphosphine oxide (m-BAPPO). In the synthesis of copolyimides 3,3?-diamino-diphenyl sulfone (DDS) was also used as the diamine, as well as 2,2?-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Copolyimide films were prepared by thermal imidization. Hybrid materials containing 5 % SiO2 were synthesised further by sol-gel technique. The Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (NMR) confirmed the expected structure. Dynamic mechanical analysis (DMA) demonstrated that m-BAPPO based copolyimides had lower glass transition temperatures (Tg) than BAPPO based copolyimides. m-BAPPO containing copolyimide without silica shifted the thermal decomposition temperature to a higher value. The moduli and strength values of BAPPO diamine containing copolyimide and its hybrid were higher than those of m-BAPPO containing materials. The contact angle measurements showed the hydrophobicity. Scanning electron microscope (SEM) analysis exhibited the silica particles dispersion in the copolyimides. These copolyimides may be used in the coating industry. The CO2 permeability and the permselectivity were the highest among the other values in this study, when m-BAPPO containing copolyimide in the absence of silica was used. The gas permeabilities obtained from this work were in this decreasing order: PCO2 > PO2 > PN2.

Preparation and Properties of Copolyimides Containing Fluorine and Alicyclic Group

The copolyimides containing fluorine and alicyclic groups were synthesized from 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and two dianhydrides, 1,2,3,4-cyclobutanetrtracarboxylic dianhydride (CBDA) and 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA) in various mole ratios via thermal imidization. The introduction of fluorinated group and alicyclic structure into polyimide improved the transparency of copolyimides. The structure and properties of copolyimides were characterized by FT-IR, UV-vis and solubility testing, and the effect of monomers on the properties of polyimides was also investigated. These experimental results showed that the copolyimides containing a higher mole ratio of CBDA have higher optical transparency and better solubility in organic solvents.

Synthesis of phthalic end-capped copolyimides and their adhesive properties

A series of molecular-weight-controlled aromatic copolyimides based on anhydrides 4,4′-oxydiphthalic anhydride (ODPA) or/and 2,3,3′,4′-biphenyltetracarboxylic dianhydride (α-BPDA) were prepared by polycondensation reaction with mixture of diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and 4,4′-diaminodiphenylsulphone (DDS) in the presence of phthalic anhydride (PA) as end-capping agent. The effect of the chemical structure of the copolyimides on solubility, rheological behavior, thermal stabilities and adhesive properties was investigated. Experimental results suggested that the solubility and thermal properties of copolyimides could be improved by incorporation of asymmetric α-BPDA. The copolyimide TPI-B (α-BPDA/6FAPB-DDS/PA) exhibited better solubility with the solid content as high as 45 wt.% in N, N-dimethylacetamide and high thermal stability with the Tg of 306 °C. TPI-A (ODPA/6FAPB-DDS/PA) and TPI-C (α-BPDA-ODPA/6FAPB-DDS/PA) could be produced into glass-cloth-supported adhesive films. TPI-A adhesive film gave better adhesive properties at room temperature with lap shear strength of 16.41 MPa and T-peel strength of 2.1 kN m−1, which attributed to its flexible structure and good melt processability. TPI-C adhesive film exhibited higher adhesive properties at elevated temperature with the lap shear strength exceeding 9 MPa at 280 °C. The copolyimides with combination of rigid and flexible structures could afford good melt flow behavior and high thermal stability, which yielded good adhesive properties at high temperature.

Synthesis and properties of copolyimides containing naphthalene group

Several series of copolyimides were synthesized from various ratios of two diamines with aromatic tetracarboxylic dianhydrides through thermal imidization process to determine the effect of naphthalene ring on the physical properties of polymers. The copolyimides were characterized using inherent viscosity, differential scanning calorimetry (DSC), TGA, DMA, TMA and dielectric analyzer. DSC showed only a T g and exhibited that the copolyimides had a low entropy, amorphous state and formed random polymers. They retained high modulus even at high temperatures by DMA, and had measured coefficients of thermal expansion in the range of 15–57 ppm by TMA. The glass transition temperatures ( T g) of all polymers were found to be 287–321 °C by DSC. Their decomposition temperatures at 10% weight loss in nitrogen atmospheres were above 556 °C. These polymer films had dielectric constants ranging from 2.9 to 3.4 with moisture absorptions of less than 2.65%.

A study on the effect of spirocyclic structures in the main chain on the physical properties of copolyimides

A study on the effect of spirocyclic structures in the main chain on the physical properties of copolyimides

Positron annihilation properties of copolyimides and copolyamides with microphase-separated structures

The positron annihilation lifetime (PAL) of a series of copolyimides and copolyamides with microphase-separated structures was measured to investigate the effects of different hard-segment polymers on the PAL properties of soft-segment domains of poly(dimethyl-siloxane) (PDMS) and poly(ethylene oxide) (PEO). The lifetime (τ3) and intensity (I3) of the long-lived component are given as a function of the PDMS or PEO content for a series of copolymers, of which the density roughly obeys the additive rule except for the PDMS-segmented copolyamides. The PDMS-segmented copolyimides and copolyamides show much smaller I3 values than those estimated from the additive rule. The lifetime distribution of the long-lived component for the PDMS-segmented copolyamides is composed of two components. The longer-lifetime component is attributed to pure PDMS domains, and the shorter-lifetime component is attributed to the polyamide domains, intermediate phases, and PDMS domains containing small amounts of short amide blocks. Despite the high PDMS content, the latter component is rather large. Thus, the positronium formation in the PDMS domains of the copolyimides and copolyamides is effectively reduced. This can be explained by the combination of the difference in the electron affinity of the PDMS and polyimide or polyamide segments and the incomplete phase separation. The PEO-segmented copolyimides show much smaller I3 values than those predicted from the additive rule. This is likely attributable to the effects of the intermediate phases. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1123–1132, 2000

Thermomechanical and Adhesive Properties of Copolyimides with Alchoxysilyl Group in the Polysiloxane Segments

Thermomechanical and Adhesive Properties of Copolyimides with Alchoxysilyl Group in the Polysiloxane Segments

Properties of copolyimides prepared from different tetracarboxylic dianhydrides and diamines

Properties of copolyimides prepared from different tetracarboxylic dianhydrides and diamines

Synthesis and properties of copolyimides, 2. Preparation and properties of polypyromellitimides from p‐phenylenediamine and m‐phenylenediamine

AbstractCopolymers were prepared by reacting a prepolymer consisting of an anhydride terminated polymeric acid from pyromellitic anhydride and a diamine (p‐ or m‐phenylenediamine), with the second diamine. The resulting polymeric acids were converted into polyimides by thermal cyclodehydration. The corresponding random copolyimides were prepared by a conventional procedure and their properties were compared with those of three step copolyimides of similar composition.