title: Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.
abstract: Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.
authors.affiliation: Molecular and Performance Materials Cluster, Institute of Materials Research and Engineering, Singapore 117602.
authors.forename: P Santhana Gopala
authors.initials: PS
authors.lastname: Krishnan
authors.forename: Mangala
authors.initials: M
authors.lastname: Joshi
authors.forename: Prachur
authors.initials: P
authors.lastname: Bhargava
authors.forename: Suresh
authors.initials: S
authors.lastname: Valiyaveettil
authors.forename: Chaobin
authors.initials: C
authors.lastname: He
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry* / Q000494:pharmacology; D002152:Calorimetry, Differential Scanning; D000077215:Clay; D006358:Hot Temperature; D007094:Imides / Q000737:chemistry*; D007364:Intercalating Agents / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D000077489:Piperazine; D010879:Piperazines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D012995:Solubility; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D014466:Ultraviolet Rays; D014961:X-Ray Diffraction
chemical_list: C505212:1,3-bis(4-piperidinyl)propane; C505213:4,4'-bipiperidine; D000538:Aluminum Silicates; D007094:Imides; D007364:Intercalating Agents; D010879:Piperazines; D010880:Piperidines; D001546:Bentonite; D000077489:Piperazine; D000077215:Clay