A study on the trans-crystallisation behaviour of flax fibre reinforced polypropylene composites and effect on mechanical properties

The effect of flax fiber reinforcement on crystn. behavior of polypropylene (PP) was investigated using a hot-stage optical microscope. To follow the crystn. kinetics, cooling rate and crystn. temps. were varied. Flax fibers with different processing history e.g. green flax, Duralin flax, alkali and silane treated flax were used for investigation. The effect of fiber treatment on crystn. behavior was obsd. Finally the effect of trans-crystallinity on the interfacial shear strength in micro-composites was studied by fiber pull-out metho

Transistor por efeito de campo e fotocondutor de poli(o-metoxianilina).

RESUMO: Esse artigo apresenta resultados sobre fabricação e caracterização de um transistor por efeito de campo (FET) tendo a poli(o-metoxianilina) - POMA - como material ativo. Uma adaptação de processos de microeletrônica tradicional foi feita para a confecção desse dispositivo. O FET desenvolvido apresentou modulação por voltagem de porta Vg, mas operou mesmo em Vg=0. A corrente de dreno I D aumentou significativamente sob iluminação na região da radiação visível e infravermelho próximo, mostrando o caráter fotocondutor da POMA dopada e, portanto, do dispositivo. Um modelo teórico baseado nos mecanismos de condução eletrônica da POMA, e de efeitos de interface metal-polímero foi elaborado, ajustando-se muito bem aos resultados experimentais.<br>ABSTRACT: A field effect transistor - FET made from poly(o-methoxyaniline) (POMA), which is a conductive polymer, was developed. Several modifications were carried out to adapt the procedures generally used in traditional device developments. The characteristic of the FET produced was sensible to the gate modulation, but it operates even for V G = 0. The drain current I D enhanced under visible and near infrared radiation, showing the photoconductor character of POMA and, consequently, of the device. A theoretical model, based on the electronic properties of POMA and on the metal-polymer interface, was developed which is in good agreement with the experimental results

Afm Studies Of Composite 16-mer Polyaniline Langmuir-biodgett (lb) Films

Atomic force microscopy (AFM) images of composite Langmuir-Blodgett (LB) films containing different weight percentages of cadmium stearate and 16-mer polyaniline are investigated. Upon increasing the amount of 16-mer polyaniline content in the composite, large globular structures with higher average roughness could be seen. © 1999 Elsevier Science S.A. All rights reserved.1011-3830831(1990) Langmuir-Blodgett Films, , G.G. Roberts (Ed.) Plenum Press, New YorkDhanabalan, A., Riul Jr., A., Oliveira Jr., O.N., (1998) Supramolecular Science, 5, p. 75. , and references thereinMacDiarmid, A.G., (1997) Synth. Met., 84, p. 27Dhanabalan, A., Riul Jr., A., Mattoso, L.H.C., Oliveira Jr., O.N., (1997) Langmuir, 13, p. 4882Riul Jr., A., Dhanabalan, A., Mattoso, L.H.C., De Souza, L.M., Ticianelli, E.A., Oliveira Jr., O.N., Thin Solid Films, , in pressSuwa, T., Kakimoto, M., Imai, Y., Araki, I., Iriyama, K., (1994) Mol. Cryst. Liq. Cryst, 225, p. 45Constantino, C.J.L., Dhanabalan, A., Pereira Da Silva, M.A., Cotta, M.A., Oliveira Jr., O.N., submitte

Characterization Of Langmuir-blodgett Films Of Parent Polyaniline

Conducting Langmuir-Blodgett (LB) films have been fabricated from parent polyaniline (PAni) which was doped with functionalized acids. In order to optimize experimental conditions for the formation of stable Langmuir monolayers and their subsequent transfer onto solid substrates, PAni was dissolved in ten different combinations of chloroform solutions. Use was made of camphor sulfonic acid, dodecyl benzene sulfonic acid, and toluenesulfonic acid, and of the solvents N-methyl pyrrolidine and m-cresol as processing agents. Because acidic subphases have been employed, as-deposited LB films were already doped, which was confirmed by the appearance of a polaronic band in the UV-Vis absorption spectra. The absorbance peak increases with the number of deposited layers indicating that a suitable multilayer buildup is accomplished. When analysed by atomic force microscopy, PAni LB films show a fibrillar structure with the fibril width ranging from ≈ 60 to 160 nm.284-285177180Cao, Y., Smith, P., Heeger, A.J., (1993) Synth. Met., 55-57, p. 3514Riul A., Jr., Mattoso, L.H.C., Mello, S.V., Telles, G.D., Oliveira O.N., Jr., (1995) Synth. Met., 71, p. 2067Mattoso, L.H.C., MacDiarmid, A.G., Epstein, A.J., (1994) Synth. Met., 68, p. 1Mattoso, L.H.C., Mello, S.V., Riul A., Jr., Oliveira O.N., Jr., Faria, R.M., (1994) Thin Solid Films, 244, p. 714Cheung, J.H., Rubner, M.F., (1994) Thin Solid Films, 244, p. 990Agbor, M.E., Petty, M.C., Monkman, A.P., Harris, M., (1993) Synth. Met., 55-57, p. 3789Punkka, E., Laakso, K., Stubb, H., Levon, K., Zheng, W.-Y., (1994) Thin Solid Films, 515-520, p. 243MacDiarmid, A.C., Epstein, A.J., (1994) Synth. Met., 65, p. 103Morgan, H., Taylor, D.M., Oliveira O.N., Jr., (1991) Biochim. Biophys. Acta, 1062, p. 149Cheung, J.H., (1993), Ph.D. Thesis, Massachusetts Institute of Technology, EUAMacDiarmid, A.G., Epstein, A.J., (1993) Brazilian Conf. on Polymers, p. 544. , São Paulo, Brazil, October Brazilian Polymer Association, São Carlos, BrazilMantovani, J.G., Warmack, R.J., Annis, B.K., MacDiarmid, A.G., Scherr, E., (1990) J. Appl. Polym. Sci., 40, p. 169