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PI Matrix (pi + matrix)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

In situ generated hydroxyl-terminated polybutadiene nanoparticles in polyimide films

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009
Anand Kumar Gupta
Abstract Polyimide (PI) has been extensively investigated as matrices for blends in the search for novel materials for microelectronics and engineering application. The processing of the PI with hydroxyl-terminated polybutadiene (HTPB) offers a considerable advantage to develop a material having good mechanical and thermal stability. Taking this into account, the HTPB was blended with polyamic acid, which is precursor to PI to form PI + HTPB films. A number of properties were evaluated for PI + HTPB films with ultra low concentrations of HTPB. The films prepared with ultra low concentration (10,3,1 wt%) showed unusual synergism, which is attributed to the presence of in situ generated micro/nanostructures derived from HTPB. The microhardness study was used to elucidate the actual mechanical performance due to structure formation of HTPB in a nanometer regime within PI matrix. Atomic force microscopy analysis confirmed the dispersion of HTPB at nano regime within PI matrix. The enhanced thermal stability as determined by thermogravimetric analyzer and Fourier transform infrared spectrometry was attributed to the presence of micro/nanoparticle of HTPB within the PI matrix. The water absorption isotherms were measured and their abnormal behavior was correlated with micro-/nano-sized particles in the PI/HTPB film. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:48,59, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20144 [source]

Colorless polyimide nanocomposite films: Thermomechanical properties, morphology, and optical transparency

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Hyo-Seong Jin
Abstract Polyimide (PI)/organoclay hybrid films were prepared by the solution intercalation method, using dodecyltriphenylphosphonium-mica (C12PPh-Mica) as the organoclay. The variations with organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids were examined for concentrations from 0 to 1.0 wt %. For low clay contents (, 0.5 wt %), the clay particles are better dispersed in the matrix polymer, without the formation of large agglomerates of particles, than they are for high clay contents. However, agglomerated structures form and become denser in the PI matrix for clay contents , 0.75 wt %. This is in agreement with the observed trends in the thermomechanical properties and the optical transparency, which worsen drastically when the clay content of the C12PPh-Mica/PI hybrids reaches 0.75 wt %. However, when the amount of organoclay in the hybrid is 0.75 wt %, the initial modulus of the hybrid film is at its maximum value. The PI hybrid films were found to exhibit excellent optical transparencies and to be almost colorless. It was found, however, that the transparency decreases slightly with increases in the organoclay content because of agglomeration of the clay particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

In situ generated diphenylsiloxane-polyimide adduct-based nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 1 2005
Manisha G. Goswami
Arylsiloxane was incorporated into polyimide (PI) via electronic interaction with polyamic acid (PAA)/PI, and a wide spectrum of properties were evaluated for different compositions. The samples prepared with relatively low concentrations (0.0001,0.1%) of oligomers showed unusual synergism, which is attributed to the generation of nanostructures dispersed in the continuous PI matrix. The incorporation of siloxane with bulky phenyl groups contributed to enhanced thermal stability as determined by thermogravimetric analysis. Water uptake and methanol absorption by these composites were evaluated and correlated with the underlying micro- and nanostructures. Fourier Transform Infrared (FTIR) spectroscopy was used to elucidate the probable reaction mechanism (including in situ polymerization of arylsilanol), and to study the synthetic aspects associated with the molecular composites and nanocomposites formation. POLYM. ENG. SCI., 45:142,152, 2005. © 2004 Society of Plastics Engineers [source]

Structural, thermal, micromechanical and electrical study of polyimide composite thin films incorporating indium tin oxide

POLYMER INTERNATIONAL, Issue 9 2010
Anand Kumar Gupta
Abstract Studies of composite films incorporating inorganic materials are of immense importance for current technological applications. Polyimide (PI) composite thin films incorporating indium tin oxide (ITO) at various weight ratios were processed using an in situ generation approach. The resultant product was imidized up to 350 °C to test the ability of the material to endure high temperatures without affecting the host matrix. The morphological behaviour of the PI/ITO composite films was investigated using Fourier transform infrared, scanning electron microscopy and atomic force microscopy characterization techniques. The degrees of crystallinity and ITO particle size within the PI matrix were studied using X-ray diffraction. The thermal, structural and electrical properties were analysed using thermogravimetric analysis, differential scanning calorimetry, UV-visible spectroscopy and the four-probe technique. The micromechanical properties of the composites were evaluated in terms of tensile strength, tensile modulus and elongation. An overall improvement in the properties of the composite films was observed in comparison to those of pure PI. The synergistic improvement in the composite films is associated with the interaction mechanism between ITO and PI, where ITO becomes dispersed and interacts within the PI matrix. This leads to a decrease in available free-space volume and increases the surface enrichment providing reinforcement to the matrix. Copyright © 2010 Society of Chemical Industry [source]

Preparation and properties of ternary polyimide/SiO2/polydiphenylsiloxane composite films

POLYMER INTERNATIONAL, Issue 11 2006
Zhenping Shang
Abstract A series of novel ternary polyimide/SiO2/polydiphenylsiloxane (PI/SiO2/PDPhS) composite films were prepared through co-hydrolysis and condensation between tetramethoxysilane, diphenyldimethoxysilane (DDS) and aminopropyltriethoxysilane-terminated polyamic acid, using an in situ sol,gel method. The composite films exhibited good optical transparency up to 30 wt% of total content of DDS and SiO2. SEM analysis showed that the PDPhS and SiO2 were well dispersed in the PI matrix without macroscopic separation of the composite films. TGA analysis indicated that the introduction of SiO2 could improve the thermal stability of the composite films. Dynamic mechanical thermal analysis showed that the composite films with low DDS content (5 wt%) had a higher glass transition temperature (Tg) than pure PI matrix. When the content of DDS was above 10 wt%, the Tg of the composite decreased slightly due to the plasticizing effect of flexible PDPhS linkages on the rigid PI chains. The composite films with high SiO2 content exhibited higher values of storage modulus. Tensile measurements also showed that the modulus and tensile strength of the composite films increased with increasing SiO2 content, and the composite films still retained a high elongation at break due the introduction of DDS. The density and water absorption of the composite films were also characterized. Copyright © 2006 Society of Chemical Industry [source]