Isomeric Biphenyl Polyimides. (II) Glass Transitions and Secondary Relaxation Processes

Kochi, Masakatsu; Chen, Chunhai; Yokota, Rikio; Hasegawa, Masatoshi; Hergenrother, P. M.

doi:10.1177/0954008305055557

Cited by 49 publications

(25 citation statements)

References 16 publications

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“…As for Φ5, its mobility is much higher than Φ2 and Φ3 in two PI systems, showing the positive cooperative motion between Φ2 and Φ3. Possible torsion model is shown in Figure 1, and the result confirms the inference of torsion analysis via DMA method in the previous study [6]. In two PI systems, the mobility of five torsion angles shows an obvious increment at 750 K, and the same arrangement order in mobility, that is Φ5>Φ2>Φ3≈Φ4>Φ1.…”

Section: Torsion Angle Atoms Segmental Vectorsupporting

confidence: 71%

Molecular dynamics simulation on glass transition temperature of isomeric polyimide

Li¹,

Liu²,

Qin³

et al. 2009

Express Polym. Lett.

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It is an abnormal phenomenon that glass transition temperature (Tg) of isomeric polyimide (PI) is higher than its corresponding symmetrical PI. To illustrate this phenomenon at the molecular scale, we applied molecular dynamics method to predict the Tg of PI, which were prepared based on 4,4’-oxydianiline (ODA) and 3,3’,4,4’-biphenyltetracarboxylic dianhydride (3,3’,4,4’-BPDA), and its isomeric system (2,2’,3,3’-BPDA-ODA). Simulation result is consistent with experimental value. Non-bond energy plays an important role in glass transition process, for it has an abrupt change near Tg. The higher free volume fraction of isomeric PI can provide the polymer with more space to obtain segmental motion. However, from the torsion angle distribution calculations, it is shown that the torsion angle of its biphenyl group is constrained. Furthermore, from mean square displacement and vector autocorrelation functions calculations, this group is observed to rotate against other groups in the glassy state, and increases the chain rigidity to a great extent. So the isomeric PI needs much more relaxation time for the segment motion. Therefore, the higher Tg of isomeric PI is mainly attributed to the chain rigidity for the time scale, not the free volume for the space scale

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Section: Torsion Angle Atoms Segmental Vectorsupporting

confidence: 71%

Molecular dynamics simulation on glass transition temperature of isomeric polyimide

Li¹,

Liu²,

Qin³

et al. 2009

Express Polym. Lett.

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“…These transitions are labeled as b and c in order of decreasing temperature and show Arrhenius frequency dependence. This suggests time-dependent localized relaxation processes [31,32] as seen in Fig. 9.…”

Section: Dynamic Mechanical Analysismentioning

confidence: 73%

Thermomechanical characterization of thermoplastic polyimides containing 4,4'‐methylenebis(2,6‐dimethylaniline) and polyetherdiamines

Nicholls

Kull

Cerrato

et al. 2018

Polymer Engineering & Sci

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In this work, we synthesized polyimides by incorporating an aromatic diamine monomer with a methylene linker, 4,4'‐methylenebis(2,6‐dimethylaniline) (MBDMA), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. We designed the polymers to exhibit thermal properties in between those of conventional aromatic polyimides and polymers with wholly aliphatic ether diamine links. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that control of the molar ratios of the aromatic MBDMA (4,4'‐methylenebis(2,6‐dimethylaniline)) and the composition and size of the aliphatic polyetherdiamine can be used to tune the glass transition. The polymers were characterized by GPC, FTIR, NMR, thermomechanical and calorimetric analysis, and microhardness testing. POLYM. ENG. SCI., 59:221–232, 2019. © 2018 Society of Plastics Engineers

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“…Since 2000, Yokota and coworkers found a new oligomer (TriA‐PI) by replacing s‐BPDA with asymmetric monomer 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (a‐BPDA). This oligomer demonstrates higher T g , good mechanical properties, in addition to low melt viscosity …”

Section: Introductionmentioning

confidence: 96%

Novel acetylene‐terminated polyimide oligomers with excellent processability and high toughness of films

Wang

et al. 2015

J of Applied Polymer Sci

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A series of acetylene-terminated imide oligomers based on 2,3,3 0 ,4 0 -Diphenyl ether tetracarboxylic acid dianhydride (a-ODPA), 3,4 0 -Oxydianiline (3,4 0 -ODA), and 3-Ethynylaniline (3-EA) with different molecular weights were synthesized by using acetic anhydride and triethylamine as dehydrating agent. Their main structure was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal curing processing was characterized by FT-IR and differential scanning calorimetry (DSC). All the uncured imide oligomers showed excellent solubility (more than 30 wt %) in organic solvent such as N,N-dimethylacetamide (DMAc) and Nmethyl-2-pyrrolidone (NMP). These imide oligomers also possessed a very low viscosity, thus provided better processing window. These oligomers were formulated into thermosetting films by thermal crosslinking of the ethynyl groups. The properties of cured films were evaluated by dynamic mechanical thermal analysis (DMA), thermogravimetric analysis (TGA), and tensile measurement. The glass transition temperature (T g ) and elongation at break of the cured films were found to be almost >2608C and >9.2%, respectively. The cured films in air resulted in higher thermal stability than those under N 2 atmosphere. Experimental results suggested that the introduction of asymmetric and flexible ether-hinge with 3-EA in polyimide oligomers can improve the processability of the imide oligomers and the toughness for a cured sample without sacrificing their thermal-oxidative stability.

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Isomeric Biphenyl Polyimides. (II) Glass Transitions and Secondary Relaxation Processes

Cited by 49 publications

References 16 publications

Molecular dynamics simulation on glass transition temperature of isomeric polyimide

Molecular dynamics simulation on glass transition temperature of isomeric polyimide

Thermomechanical characterization of thermoplastic polyimides containing 4,4'‐methylenebis(2,6‐dimethylaniline) and polyetherdiamines

Novel acetylene‐terminated polyimide oligomers with excellent processability and high toughness of films

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