Polymers polyimide

Polyamide or polyimide polymers are resistant to aliphatic, aromatic, and chlorinated or fluorinated hydrocarbons as well as to many acidic and basic systems but are degraded by high-temperature caustic exposures. 

Table 18.13 Typical properties of fabricated unfilled and 15% graphite-loaded polyimide polymers...

Potyrailo, R. A. Sivavec, T. M., Boosting sensitivity of organic vapor detection with silicone block polyimide polymers, Anal. Chem. 2004, 76, 7023 7027... 

Multinuclear NMR spectroscopy is being used increasingly to study catalytic reactions. In order for such studies to be possible, all contact betv een the sample solutions and the metal part of the cell body has to be avoided because of possible catalytic effects. All materials in contact vith the sample solution have to be chemically inert and nonmetallic quartz, glass, PTFE, Vespel (polyimide polymer, Dupont de Nemours), PCTFE (poly-chlorotrifluoroethylene), Viton seals, etc. 

Fig. 37. Difference spectrum (a-b) obtained by subtraction of the uncured polyimide resin spectrum (with lines artifically broadened), b) from that of the cnred polyimide polymer (a). Small deviations in the difference spectrum should be ignored since line broadening across the cured polymer may not be uniform (reprinted from Ref.2141 with permission)...

K. Tanaka, H. Kita, M. Okano and K. Okamoto, Permeability and Permselectivity of Gases in Fluorinated and Non-fluorinated Polyimides, Polymer 33, 585 (1992). 

Polyimides are compounds that contain two anhydride groups, which will react with primary amines or isocyanates to form polyimide polymers that are very stable linear polymers. 

Arnold CA Summers JD, McGrath JE (1989) Synthesis and physical behavior of si-loxane modified polyimides. Polym Eng Sci 29(20) 1413... 

Fig. 21. Dynamic thermal stability [121] of a variety of polymeric electro-optic materials. All materials involve the Disperse Red chromophore. Trace 1 PMMA composite material trace 2 chromophore covalently attached by one end to a soft (PMMA-like) matrix [138] trace 3 DEC chromophore with both ends attached to a soft polymer matrix [138] trace 4 Disperse Red chromophore covalently attached at one end to a polyimide polymer matrix [121] trace 5 DEC-type chromophore with both ends attached to a sol-gel type matrix [139]...

Keywords ceramic thin films, titania, polyimides, polymer matrix composites 1. Introduction... 

Attaching thin adherent titania films to polyimide polymers demonstrates the promise of such coatings as barrier layers. Potential applications must examine the effect of the deposition process on the mechanical and thermal properties of the polymer and the requisite thickness of the ceramic layer. Nevertheless, the low-cost and convenience of LPD coatings, their mild conditions and their lack of line-of-site limitations, recommend their use. 

Goodwin AA, Whittaker AK, Jack KS, Hay JN, Forsythe J (2000) Absorption of low molecular weight penetrants by a thermoplastic polyimide. Polymer 41(19) 7263-7271... 

The first reported (8) siloxane-polyimide polymer was synthesized from l,3-bis(aminopropyl)-l,l,3,3-tetramethyldisiloxane and pyromellitic dianhydride. This material was described as a soluble, thermoplastic polyimide. Many other siloxane-polyimide polymers have been prepared via similar methodology using other dianhydrides and diamines (9). 

The polymers and copolymers described in this chapter were derived fi"om the novel anhydride-terminated disiloxane, 5,5 -bis(l,l,3,3-tetra-methyl-1,3-disiloxanediyl)norbornane-2,3-dicarboxylic anhydride (DiSiAn) (14). Both siloxane-polyimide polymers and copolymers based on DiSiAn and its polysiloxane derivatives were investigated. This chapter describes the synthesis, characterization, and physical properties of these materials. 

Table II. Tensile Properties of DiSiAn-Polyimide Polymers and Copolymers...

Sekkat, Z., Pretre, P., Knoesen, A., Volksen, W., Lee, Y. Y., Miller, R. D., Wotxl, J., and Knoll, W. Correlation between polymer architecture and sub-glass-transiiion-temperature light-induced molecular movement in azo-polyimide polymers influence on linear and second- and third-order nonlinear optical processes. Journal of the Optical Society of America B (Optical Physics), vol. I S, (no. 1), Opt. Soc. America, m. 1998, p. 401-41.1. 

Sekkat et. al. have observed photoinduced AR in these azo-polyimide polymers even at temperatures far below the polymer One can use the... 

In this section, we are going to discuss the results of optical control of EFISH signal in azo-polyimide polymers obtained by Sekkat et al, and compare these results with our results from the THG described in the previous section. 

The chemical structure of the polyimide polymers (named PI-1 and PI-2) studied by Sekkat et al. is shown in Figure 12.12. They prepared the polymer samples by spin-casting onto glass substrates. PTl was cast from a cyclohexanone solution and PI-2 from 1,1,2,2- tetrachloroethane. The Tg values of PI-1 and PI-2 were determined to be 350°C and 252 C, respectively, by scanning calorimetry method. The thicknesses of the PI-1 and PI-2 films were, respectively, approximately 0.72 im and 0.14 im, and their respective optical densities were approximately 0.79 and 0.3 at 543.5 nm. Details of the preparation and characterization of the samples can be found in References 3 and 20. In their EFISH experiment, a typical corona poling technique was used to pole the samples, with a dc electric field about 2-3 MV/cm across a 1-2 lm thick polymer film. They used the SHG output from the EFISH experiment to in situ monitor the photochemical change in the third-order susceptibility of the PI-1 and PI-2 polymers. 

Analytical pyrolysis has been successfully used for monitoring the curing process of certain polyimide polymers. For example, the polyimide Matrimid 5292 is obtained from two components in a reaction as shown below ... 

Figure 6 shows the uncorrected excitation and emission spectra of a film of the poly(amide acid) after thermal treatment in an air filled oven for 30 minutes at each of the temperatures ranging from 80°C to 350°C. The excitation and the emission wavelengths were 480nm and 550 nm, respectively. The fluorescence intensity at 550 nm increased steadily when the cure temperature was raised from 80 C to 350°C. The uncorrected excitation spectra were more complex. A band at 460 nm appeared at the expense of the one at 330 nm after the second heating. However, the intensity of the band at 330 nm relative to the one at 460 nm increased steadily with additional thermal treatments. In any event, the formation of this polyimide polymer can be readily monitored in-situ by fluorescence spectroscopy. 

Ve have described three fluorescence techniques for monitoring the cure of epoxy resins. The first one is based on intramolecular excimer fluorescence, the second one is based on the enhancement of fluorescence intensity with the medium viscosity, and the third one is based on the measurement of the translational diffusion coefficient of a fluorescent probe. Finally, we have demonstrated the fluorescence monitoring of the formation of a polyimide polymer. 

Phlegm, H. K. 2001. A comparison of molded polyaryletherketones and compression molded polyimide polymers in automotive applications. Master s thesis, University of Detroit-Mercy, pp. 1, 7, 11. 

The polyimide polymers were formed by an established procedure (17) involving the addition of stoichiometric quantities of benzophenone-tetracarboxylic dianhydride (sublimed) to the diamine dissolved in anhydrous dimethylacetamide. The polyamic acid solution was cast on Teflon, warmed (80° to 90°C) to drive off solvent, then gradually heated to a temperature of 180°C. The polyimide forms rapidly at 120 to 150°C. 

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