A theoretical analysis of the flexibility of polyimides and polyamido-acids

Birshtein, T.M.; Goryunov, A.N.

doi:10.1016/0032-3950(79)90158-8

Cited by 9 publications

(3 citation statements)

References 8 publications

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“…This value increases up to 6.39 kcal/mol for the model compound, but is still only slightly higher than the rotational barriers on the bridging groups of the flexible chain aromatic polyamides and polyimides based on conventional diamines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyloxide, etc. 15 The …”

Section: Internal Rotationmentioning

confidence: 98%

Soluble aromatic polyimides and polyamides based on 4,4′‐diaminotriphenylmethane

Likhatchev

Alexandrova

Tlenkopatchev

et al. 1995

J of Applied Polymer Sci

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SYNOPSISAromatic polyamides and polyimides were synthesized from 4,4'-diaminotriphenylmethane (DA-TPM) for studying their solubility, thermal, and mechanical properties. The polymers were found to be soluble in amide solvents and pyridine, and this could be attributed to the practically free rotation of the polymer chain segments around the bridging group within the DA-TPM and the effect of its pendant phenyl ring. The polyimides and polyamides exhibited well-distinguished glass transition in the range of temperatures, which is typical for flexible-chain polymers. For the polyimides, significant differences in solubility and mechanical properties were observed between the samples prepared by chemical and thermal imidization of poly(amic acids). Thermal imidization brought about remarkably less soluble brittle films. 0 1995 John Wiley & Sons, Inc.

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Section: Internal Rotationmentioning

confidence: 98%

Soluble aromatic polyimides and polyamides based on 4,4′‐diaminotriphenylmethane

Likhatchev

Alexandrova

Tlenkopatchev

et al. 1995

J of Applied Polymer Sci

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“…These values are in agreement with the magnitudes of A reported for polyimides of different chemical structures with swing joint groups or flexible spacers. In particular, Kuhn segment lengths for aromatic polyimides were found (experimentally and theoretically) to be 1.9-3.8 nm [36], 2.5-4.2 nm [37], 1.6-4.4 nm [38], 2-3 nm [39], and 1-2 nm [40]. The high flexibility of the investigated polymers is caused by multiple internal rotation degrees within the monomer unit of the PAAs around Ph-O bonds.…”

Section: Equilibrium Rigidity Of Paasmentioning

confidence: 99%

Influence of Molecular Weight on Thermal and Mechanical Properties of Carbon-Fiber-Reinforced Plastics Based on Thermoplastic Partially Crystalline Polyimide

Vaganov,

Simonova,

Romasheva

et al. 2023

Polymers

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For the first time, a study of the influence of the molecular weight of the thermoplastic partially crystalline polyimide R-BAPB on the thermophysical and mechanical properties of carbon plastics was presented. The molecular weight of polyimide was determined using the method of light scattering and the study of the intrinsic viscosity of polyamic acid solutions. To obtain CFRPs, the uniform distribution of polyimide powder on continuous carbon fibers via electrostatic spraying and further hot calendering and pressing were applied. The study of the structure of the obtained carbon plastics via scanning electron microscopy has shown that the growth of the molecular weight of polyimide prevents the impregnation of carbon fiber with the introduced polyimide. Moreover, an increase in the molecular weight of polyimide leads to a rise in glass transition and thermal decomposition temperatures up to 590 °C, while the degree of crystallinity of CFRP falls. Nonetheless, raising the molecular weight from 22,000 to 70,000 g/mol of a binder polymer improves the interlayer fracture toughness G1C by more than five times.

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“…The ratio of the top electrode diameter to the film thickness is on the order of lo3. According to the empirical fringing capacitance correction equation published in the ASTM D150-87 ~t a n d a r d , '~ the edge effect due to Ref 11 ). .Polyimide chemistries: PMDA/ODA and BPDA/PPD (KSS values obtained Parallel-plate structure.…”

mentioning

confidence: 99%

Effect of molecular orientation on the dielectric properties of spin‐coated polyimide films

Lin

Bidstrup

1994

J of Applied Polymer Sci

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SYNOPSISThe effect of molecular orientation on the dielectric properties of spin-coated polyimide films has been studied in situ for pyromellitic dianhydride with 4,4'-oxydianiline ( PMDA/ ODA) and biphenyldianhydride with p-phenylenediamine (BPDA/PPD) . The degree of molecular orientation is characterized by the optical anisotropy between the in-plane and the through-plane refractive indices. The through-plane dielectric properties are measured by fabricating parallel-plate capacitors directly onto the silicon substrate. Both the birefringence and the dielectric constant of PMDA/ODA polyimide vary with film thickness; however, these properties are independent of film thickness for BPDA/PPD films. T o confirm that the measured dielectric constant obtained from the parallel-plate structures is free from a significant edge effect, finite element modeling of the electrostatic potential within the dielectric is performed. Models for both isotropic and anisotropic dielectric properties indicate that the fringing effects are indeed negligible for the film thicknesses examined. Thus, the changes observed in the measured dielectric constant are attributed to the variations in the molecular orientation. The optical anisotropy observed for the polyimides suggests a corresponding dielectric anisotropy in the films. An estimation using the Maxwell relation indicates that the dielectric anisotropy at lo5 Hz is 0.31 for PMDA/ ODA and 0.85 for BPDA/PPD.

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A theoretical analysis of the flexibility of polyimides and polyamido-acids

Cited by 9 publications

References 8 publications

Soluble aromatic polyimides and polyamides based on 4,4′‐diaminotriphenylmethane

Soluble aromatic polyimides and polyamides based on 4,4′‐diaminotriphenylmethane

Influence of Molecular Weight on Thermal and Mechanical Properties of Carbon-Fiber-Reinforced Plastics Based on Thermoplastic Partially Crystalline Polyimide

Effect of molecular orientation on the dielectric properties of spin‐coated polyimide films

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