Navegando por Palavras-chave "thermal properties"

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    Desenvolvimento de compósitos de resina epóxi/não tecido utilizando refugo da indústria de não tecido
    (Universidade Federal de São Paulo (UNIFESP), 2016-06-20) Leite, Jose Rodolfo Vieira [UNIFESP]; Passador, Fabio Roberto [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Non-wovens are formed by extrusion processes and may be produced in an economical manner which are used in disposable products. Medical and hospital sector and packaging sectors are the largest consumers of non-wovens. The non-woven industry generates a large content of solid waste from the production. The wastes of non-wovem are fibers of various polymers, including polyamide, polyethylene, polypropylene, polyester and polystyrene. These materials have great interest for use as a reinforcing agent in thermosetting matrix, contributing to an improvement in the mechanical properties of these matrices, and also collaborating with the decrease of the solid residue of the non-woven industry. In this work, epoxy/nom-woven composites were prepared using two different types of waste of non-wovenssupplied fromParaíba´s Valley industries. The composites were prepared by hand lay-up thecnique and characterized by thermal, mechanical and morphological properties. The addition of 0.6 to 1.2 phr of fibers of PE/PP non-woven increased the glass transition temperature of the epoxy resin in the composite, besides improving the mechanical properties, as evidenced by the increase in elastic modulus and flexural modulus of the composites. For composite reinforced with laminated of PE/PP/PET non-woven, which presents a preferred direction of the fibers, resulting from the consolidation of these laminates, the mechanical properties of the composite are influenced by the direction of the fibers. Composites whit laminates arranged longitudinally to the direction of consolidation had superior mechanical properties. Thus, residues of the non-woven industry can be used as fillers for preparation of composites materials and can be an alternative for decreasing the amount of discharge of the product, using a low cost and simple method.
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    Influence of photodegradation with UV radiation in biotreatment with Paecilomyces variotti on PHBV/GNS nanocomposites
    (Inst Engineering Technology-Iet, 2018) Montagna, Larissa Stieven [UNIFESP]; Montanheiro, Thais Larissa do Amaral [UNIFESP]; Borges, Aline Chiodi; Koga-Ito, Cristiane Yumi; Lemes, Ana Paula [UNIFESP]; Rezende, Mirabel Cerqueira [UNIFESP]
    Graphite nanosheets (GNSs) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites were prepared by solution casting method. This study aimed to evaluate the effects of previously phototreatment with ultraviolet (UV) radiation on the biotreatment with Paecilomyces variotti of neat PHBV and PHBV/GNS nanocomposites. Some samples of PHBV film were submitted only to biotreatment with P. variotti during 120 days
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    Investigations of the Electrical Conduction Mechanisms of Polyaniline-DBSA/Poly(acrylonitrile-butadiene styrene) Blends
    (Wiley-Blackwell, 2014-09-05) Campos, Milton; Miziara, Thiago A. S.; Cristovan, Fernando H. [UNIFESP]; Pereira, Ernesto C.; UNIP Univ Paulista; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de São Carlos (UFSCar)
    The electrical properties of Al/PANI-DBSA/ABS/Au blend with PANI (5%) w/w have been investigated by using of current-voltage (I-V) measurements, in a temperature range of 100-313 K. the analysis of I-V characteristics in the forward direction was based on thermionic emission mechanism for applied electrical field till similar to 3 x 10(2) V/cm. the thickness dependence of the current-voltage relationship, clearly demonstrates that the electrical current for larger fields is space charge limited current (SCLC). Temperature dependences of the ideality factor, barrier height, and series resistance have been calculated. the mobility of carriers which is temperature dependent was calculated using the trap free SCLC as 1.53 x 10(-4) cm(2) V-1 s(-1) at room temperature. (C) 2014 Wiley Periodicals, Inc.
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    A statistical approach to evaluate the oxidative process of electrospun polyacrylonitrile ultrathin fibers
    (Wiley, 2017) de Oliveira Junior, Mauro Santos [UNIFESP]; Manzolli Rodrigues, Bruno Vinicius; Marcuzzo, Jossano Saldanha; Guerrini, Lilia Muller [UNIFESP]; Baldan, Mauricio Ribeiro; Rezende, Mirabel Cerqueira [UNIFESP]
    A systematic study using design of experiments was applied in order to map out the thermal stabilization of electrospun polyacrylonitrile mats and to investigate how oxidation and cyclization reactions are affected by rate, temperature, and time in an oxidative environment. Cyclization indexes were estimated by a simple methodology based on differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy data. Values of enthalpy and relative intensities of bands assigned to CN and CN bonds were used on calculation. The statistical planning applied in this study was important to show that not always longest treatment is effective to stabilize polyacrylonitrile, but also samples obtained in less than 3 h presented low values of exothermic peak on DSC, values of cyclization indexes near to 90%, both from DSC and Fourier transform infrared spectroscopy techniques, reduced weight loss in thermogravimetric analysis and O/C ratio higher than 10% by X-ray photoelectron spectroscopy, that are appreciated characteristics to a precursor of high-performance carbon materials. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45458.