Cure Studies of Fluorinated Polyamic Acids by Thermal-IR

1992 ◽  
Vol 264 ◽  
Author(s):  
Robert T. Roginski ◽  
Douglas E. Fjare
Keyword(s):  
Ir Spectroscopy ◽  
Phthalic Anhydride ◽  
Amic Acid ◽  
Back Reaction ◽  
Curing Process ◽  
Thermal Curing ◽  
Additional Mechanism ◽  
Polyamic Acid

AbstractThe thermal curing chemistry of a fluorinated polyamic acid based on 6FDA (hexafluoroisopropylidene bis(phthalic anhydride)) and APBP (4,4′-bis(4-aminophenoxy)biphenyl) was studied by thermal-IR spectroscopy. Anhydride formation was observed at intermediate cure temperatures and maximized at approximately 220°C. The degree of anhydride formation was affected by the solvent, being least in 2-methoxyethyl ether and increasing in the solvent order: 2-methoxyethyl ether < NMP < 2-(2-ethoxy)ethoxyethanol. In addition to the back reaction of amic acid to anhydride and amine, at least one additional mechanism of anhydride formation is observed. The onset of the second mechanism of anhydride formation is coincident with the onset of imidization, which leads us to propose that water generated by imidization can react with anhydride during the curing process, before escaping from the film, to form diacid. Cyclization of diacid to anhydride is proposed as the second mechanism of anhydride formation.

scholarly journals Polyamic Acid Nanofibers Produced by Needleless Electrospinning

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Oldrich Jirsak ◽  
Petr Sysel ◽  
Filip Sanetrnik ◽  
Jakub Hruza ◽  
Jiri Chaloupek
Keyword(s):  
Pressure Drop ◽  
Ir Spectroscopy ◽  
Polyamic Acid ◽  
Needleless Electrospinning ◽  
Electrospinning Method ◽  
Filtration Properties ◽  
To Receive ◽  
Polyimide Precursor ◽  
Oxydiphthalic Anhydride

The polyimide precursor (polyamic acid) produced of4,4′-oxydiphthalic anhydride and4,4′-oxydianiline was electrospun using needleless electrospinning method. Nonwoven layers consisting of submicron fibers with diameters in the range about 143–470 nm on the polypropylene spunbond supporting web were produced. Filtration properties of these nanofiber layers on the highly permeable polypropylene support—namely filtration effectivity and pressure drop—were evaluated. Consequently, these polyamic acid fibers were heated to receive polyimide nanofibers. The imidization process has been studied using IR spectroscopy. Some comparisons with the chemically identical polyimide prepared as the film were made.

Preparation and properties of polyimide-based nanocomposites containing functionalized Fe3O4 nanoparticles

2019 ◽  
Vol 32 (4) ◽  
pp. 418-428 ◽  
Author(s):  
Maryam Rasekh ◽  
Zahra Rafiee
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Coupling Agent ◽  
Analysis Data ◽  
Amic Acid ◽  
Thermal Curing ◽  
Sem Image ◽  
The Fourier Transform ◽  
Thermal Stability Of ◽  
Scanning Electron

Polyimide (PI)/Fe3O4 nanocomposites were successfully prepared via the thermal curing of different amounts of Fe3O4 nanoparticles (2, 4, 6 and 8 wt%) functionalized by 3-aminopropyltriethoxy silane as a coupling agent, containing the poly(amic acid) derived from 5-diamino- N-(4-(4,5-diphenyl-1H-imidazol)phenyl)benzamide and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride. The effect of Fe3O4 nanoparticles on the structural, thermal and magnetic properties of nanocomposites was investigated. The Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) results reveal that the surface of Fe3O4 nanoparticles is sufficiently compatible with PI through linkage of the coupling agent between Fe3O4 and the polymer. Also, the SEM image shows that Fe3O4 nanoparticles are dispersed uniformly in the polymer matrix, with a particle size of around 78 nm. The nanocomposites of 2 and 8 wt% exhibit the saturation magnetization values of 0.055 and 0.170 emu g− 1, respectively. The thermogravimetric analysis data show that the thermal stability of the nanocomposites is improved as compared to the pure PI.

Preparation and properties of graphene oxide/polyimide composites by in situ polymerization and thermal imidization process

2016 ◽  
Vol 29 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Lang Ma ◽  
Guojian Wang ◽  
Jinfeng Dai
Keyword(s):  
Graphene Oxide ◽  
In Situ Polymerization ◽  
Curing Process ◽  
Thermal Curing ◽  
Solution Blending ◽  
Blending Method ◽  
Thermal Imidization ◽  
Polyimide Composites ◽  
Properties Of Composites

Graphene oxide/polyimide (GO/PI) composites with different loadings of GO were prepared by in situ polymerization and solution blending method. By adding GO, the mechanical, electrical, and thermal properties of composites could be improved. The tensile strength of GO/PI composite with 3.0 wt% GO loading was up to 137.8 MPa, 75.5% higher than that of a pure PI. Besides, the electrical and the thermal conductivities increased with the increase of GO contents. An electrical conductivity value of 5.38 × 10−5 S m−1 and a thermal conductivity value of 0.10 W m−1 K−1 for GO/PI composites prepared via in situ polymerization at GO content of 3.0 wt% were achieved. The results indicated that in situ polymerization was able to make GO a better dispersion in the polymer matrix. Furthermore, the behavior of GO under the thermal imidization temperature was also discussed. The experimental results showed that GO could be partially reduced to graphene during the thermal curing process. Above works are conducive to the understanding of the effect and transformation of GO in the preparation process of graphene-based composites.

scholarly journals Systematic Approach to the Synthesis of Organic-Inorganic Nanocomposites Based on Dmta Measurements and Ir Spectroscopy

1998 ◽  
Vol 519 ◽  
Author(s):  
Peter Müller ◽  
Carsten Becker ◽  
Helmut Schmidt
Keyword(s):  
Double Bond ◽  
Ir Spectroscopy ◽  
Hybrid Materials ◽  
Strong Dependence ◽  
Sol Gel ◽  
Thermomechanical Properties ◽  
Thermal Curing ◽  
Molar Ratios ◽  
Double Bond Conversion ◽  
Titania Sol

AbstractSol-gel derived organic-inorganic hybrid materials with potential fields of application as refractive optical components for example laser diode bars and ophthalmic lenses are presented. The main components of the hybrid materials under investigation are precondensed methacryloxypropyltrimethoxysilane (MPTS, denoted: M) with an organically polymerisable methacrylic functionality and tetraethyleneglycoldimethacrylate (TEGDMA, denoted: T) as crosslinking organic monomer with two polymerisable double bonds. The molar ratios of the components ranged from M/T 10/90 up to M/T 70/30. The polymer derived from pure TEGDMA (M/T 0/100) served as a reference material. In addition to this nanoscaled TiO2 particles (5 wt.% and 10 wt.%) were incorporated in the organic-inorganic M/T 30/70 matrix to increase the refractive index of the resulting nanocomposites. For the preparation of the different systems, precondensed MPTS was mixed with TEGDMA, the nanoparticulate titania sol (when used), an appropriate photoinitiator and a thermoinitiator. The reaction mixtures were polymerised photochemically and/or thermally. The propagation of the free radical polymerisation reaction after photopolymerisation and subsequent thermal curing was followed by IR-spectroscopy, showing that the degree of double bond conversion is strongly increased by the thermal curing step. Incorporation of increasing amounts of TiO2 nanoparticles resulted in reduction of the double bond conversion compared to the corresponding unfilled system. The homogeneous dispersion of the titania particles in the completely cured M/T 30/70 matrix could be manifested by high resolution transmission electron microscopy (HTEM). The thermomechanical properties of the completely cured nanocomposites were monitored by dynamic mechanical thermal analysis (DMTA) showing a strong dependence on composition.

Liquid Etch of Moisture Resistant Polyimides

1992 ◽  
Vol 264 ◽  
Author(s):  
D. E. Fjare ◽  
A. J. Beuhler ◽  
C. A. Navar
Keyword(s):  
Amic Acid ◽  
Aliphatic Amines ◽  
Polyamic Acid ◽  
Base Component ◽  
Wet Etch ◽  
Moisture Resistant ◽  
Active Base

AbstractA new wet patterning technology which is particularly well suited to moisture resistant polyimides is described. The key feature is a two step wet-etch with the photoresist patterned and the amic acid etched in sequential steps. A higher degree of sidewall control than previously attained is possible because the etchant can be tailored specifically for the polyamic acid. The etchants operate by the polarity shift mechanism conventionally used to etch polyamic acids with hydroxide bases, but instead use the weaker aliphatic amines as the active base component. Alcohols are used to adjust the polarity of the solvent.

scholarly journals Optimized Synthesis of Biodegradable Elastomer PEGylated Poly(glycerol sebacate) and Their Biomedical Application

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 965 ◽  
Author(s):  
Yanxiang Wang ◽  
Haiwa Wu ◽  
Zihao Wang ◽  
Jingjing Zhang ◽  
Jing Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Biomedical Applications ◽  
Bone Repair ◽  
Biomedical Application ◽  
Vascular Reconstruction ◽  
Curing Process ◽  
Thermal Curing ◽  
Potential Applications ◽  
Degradation Behaviors

Poly(glycerol sebacate) (PGS), a biodegradable elastomer, has been extensively explored in biomedical applications for its favorable mechanical properties and biocompatibility. Efforts have been made to fabricate multifunctional PGS copolymer in recent years, in particular PGS-co-PEG (poly(glycerol sebacate)-co-polyethylene glycol) polymers. However, rare research has been systematically conducted on the effect of reactant ratios on physicochemical properties and biocompatibility of PGS copolymer till now. In this study, a serial of PEGylated PGS (PEGS) with PEG content from 20% to 40% and carboxyl to hydroxyl from 0.67 to 2 were synthesized by thermal curing process. The effects of various PEGS on the mechanical strength and biological activity were further compared and optimized. The results showed that the PEGS elastomers around 20PEGS-1.0C/H and 40PEGS-1.5C/H exhibited the desirable hydrophilicity, degradation behaviors, mechanical properties and cell viability. Subsequently, the potential applications of the 20PEGS-1.0C/H and 40PEGS-1.5C/H in bone repair scaffold and vascular reconstruction were investigated and the results showed that 20PEGS-1.0C/H and 40PEGS-1.5C/H could significantly improve the mechanical strength for the calcium phosphate scaffolds and exhibited preferable molding capability for fabrication of the vascular substitute. These results confirmed that the optimized PEGS elastomers should be promising multifunctional substrates in biomedical applications.

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