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Abstract In this study, walnut shell particles obtained through the grinding of walnut shells were used as a reinforcing material and pumice powder as a filler for developing epoxy-based composites characterized by reduced flammability. Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Underwriters Laboratories (UL)-94 vertical tests were carried out for evaluating the effectiveness of these pumice powder treatments. Under the UL-94 vertical test, composites (S1, S2, S3, S4, S5 and S6) with 20% pumice powder (i.e., by mass content of walnut particles were not self-extinguished, and could not be classified. S7 and S8 composites (40wt% and 50%) assigned a V-2 rating, which was the least flammable composite However, the mechanical tensile tests showed that the pumice powder treated composites increased their tensile strength. The morphological analysis showed an enhancement of the interfacial adhesion of the composites achieved by pumice powder.

Abstract Ceramics are widely employed as thermal insulating materials for thermal barrier coatings (TBC) due to their low thermal conductivity, chemical stability, and high wear and corrosion resistance at high temperatures. The aim of this work was to study the influence of the CO2 laser beam parameters on the single-step irradiation of pre-placed yttria-stabilized zirconia (YSZ) powders on NiCrAlY/AISI 316L substrates. In order to increase the coating’s lifetime and performance, it is proposed a laser sintering of powder-beds (LSP) technique to obtain homogenous YSZ coatings, with controlled surface microstructures. The obtained coatings were characterized by optical microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction (XRD). The laser intensity and interaction time were the main laser parameters used to control the surface temperature and the combination of these parameters were used to establish a process chart. The LSP resulted in controlled smooth coating surfaces and columnar growth with submicrometric grain size. XRD analyses showed the prevalence of non-transformable tetragonal zirconia, which is known to exhibit higher stability and thermal wear resistance.

Abstract The present study deals with the fabrication of epoxy composites reinforced with synthesized nano-zirconia, and to study their properties for high-voltage applications. The epoxy composites were extensively characterized to understand the morphology, mechanical, thermal, and electrical insulating behavior. The surface morphology and molecular structure of the nanoparticle and its interaction with the base matrix ware investigated by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction (XRD). XRD profiles confirmed that particles were crystalline and nanosized. Moreover, the tensile characteristics were analyzed using various theoretical models that predict the stiffness of these composites. The glass transition temperature of the epoxy/ZrO2 composite increased with the increase in nanofiller content. The AC breakdown voltage reached a maximum of 14.8 kV for 2 wt% ZrO2 composite. The prepared composites have the potential to act as high-performance insulation materials.

ABSTRACT This research was conducted with the objective of evaluating the thermal inertia and hysteresis of the following materials in a wind tunnel: hollow copper sphere with 150.0 mm diameter used as standard in globe thermometers, hollow brass sphere with 75.0 mm diameter, and two hollow plastic spheres with 115.5 and 69.7 mm diameter. The results showed that the thermal inertia and hysteresis for the hollow copper sphere were approximately 24 and 28 min, respectively; these values were bigger than those obtained for the other spheres, implying faster responses of these. While there were no statistical differences in the measurements conducted by globe thermometers which are used to indicate the black globe temperature with the different types of spheres mentioned above under indoor environment conditions, i.e., with no wind and solar radiation, the wind causes faster cooling in smaller spheres under outdoor environment conditions, which may denote erroneous interpretations of the measurements at those instants. It was concluded that it is possible to replace the hollow copper sphere of diameter 150 mm by other types of spheres to measure the black globe temperature. However, this requires knowledge of the response times of the spheres as well as corrections to be made in the measurements with respect to the globe thermometer standard.

Abstract: The objective of this work was to characterize the starch of Xanthosoma riedelianum, commonly known as “mangarito” in Brazil, and to evaluate its properties for the food industry. The starch was characterized as to its morphology and its thermal and technological properties. Morphology was evaluated by the analysis of granule size distribution, scanning electron microscopy, and X-ray diffraction. The thermal properties were examined by determining the initial, peak, and conclusion gelatinization temperatures, whereas the technological properties were obtained by analyzing viscosity, swelling power, solubility index, paste clarity, and syneresis. Although the extraction of X. riedelianum starch showed a low yield, the species is a source of starch with a high sticking temperature, mechanical stirring resistance, tendency to retrograde, and final viscosity. Therefore, this starch is ideal for products that require high viscosity, such as pie fillings, puddings, children’s foods, and bakery products, and its paste, which is opaque and viscous, can also be used in the formulation of broths.

This work had the main goal of investigating the behavior of a thermoset polymer, epoxy LY 1316, making a survey of the chemical compatibility of this material in the refrigerant fluid R410a, currently used in air conditioning equipment, so creating a methodology that evaluates different polymers. The operating conditions of the system were simulated by immersing samples in liquid R410a for a period of fourteen days, according to the ASHRAE 97 standard, then the effects of this immersion on their mechanical and thermal properties were evaluated. A control group was created in order to evaluate possible effects of temperature, and to differentiate them from the effects of the refrigerant. No significant variations were observed in the analyzes of DSC, TGA, FTIR and on tensile tests for all samples, thus concluding chemical compatibility between the epoxy and the R410a refrigerant. [ABSTRACT FROM AUTHOR]

The present work refers to the study of the incorporation of a solid residue generated by the leather industry, called wet blue leather sawdust originating from the countersink operation which standardizes the thickness thereof, in a polyurethane matrix to form microcomposites. This waste is classified as Class I residue by the standard NBR 10.004, of 2004. Therefore, the objective of this research is the reuse of this waste, incorporating it as reinforcement, in polyurethane matrix. The method consists of grinding and sieving the leatherdust, which must pass through the oven drying process, to be added during the in situ polymerization process. This charge was incorporated in proportions of 0.5, 2.0 and 5.0% by mass of the pure polymer. Thus, the modification will be verified in the thermal properties of the composite formed, by means of the FT-IR, TGA, DSC, XRD and MEV analyzes. As a result, there was increased crystallinity and, consequently, increased thermal resistance as the concentration of the charge of each microcomposite increases. Therefore, this alternative proved to be a possibility for the destination of wet blue leather residue. [ABSTRACT FROM AUTHOR]

Abstract In this study, four different wood species walnut (Juglans regia L.), chestnut (Castanea sativa Mill.), Poplar (Populus nigra), scotch pine (Pinus sylvestris L.) were chosen and test samples were prepared according to TS 2470 principles. Especially the pine wood by taking the structure (with fungus, fungus/insect, insect), flawless wood structure is compared with the flawed wood structure. The impregnation process was carried out according to ASTM D 1413 -76 principles. Effects of the chemical characteristics of the determined Stone Water (Firetex) on the thermal decomposition properties of wood (burning degrees, degradation temperature points and residue amount) were determined with TGA (thermogravimetric analysis). According to the results of the experiment; the highest retention value was found in poplar (23.56%) and the lowest retention (12.79%) in chestnut was determined. Amount of residue; 60.84% of the highest on scotch pine wood with fungus and 56.70% of the lowest value was determined on poplar wood. Thermal deterioration was determined between 226.41-405.04 oC on wood .

Abstract The life cycle of a product depends to a great extent on its reuse and ease of recycling. This work had developed of composite materials of reprocessed polypropylene composites with rice husk ash (RHA) and sugarcane bagasse ash (SBA) through the coextrusion and injection processes as main purpose. The polymeric matrix was reprocesed until six generations by the injection technique. The reprocessed PP was mixed in 80:20 proportions with respect to filler mineral, using maleic anhydride as coupling agent in a coextrusion machine. The new series of composite materials were analyzed thermal, mechanical, rheological and morphologically. The incorporation of ashes in the PP matrix achieved characteristics of improved tensile strength, conserving the thermal properties. For this reason, this work presents an alternative for the manufacture of composite materials from post-industrial waste.

In this work, the effect of silica particle size and organosilane type used in the silica organofunctionalization on the thermal and mechanical properties of high-density polyethylene (HDPE)/silica composites were evaluated. HDPE/silica composites were prepared by the extrusion method using two types of silica: fumed silica, with nanometric particle size and silica gel, micrometric, modified with organosilanes containing methyl or octyl functional groups. Silicas were added to the HDPE at 1% v/v concentration. The addition of the silicas to the HDPE did not influence the melt (Tm) and the crystallization (Tc) temperatures of the resulting composites but influenced its crystallinity. The mechanical property of Izod impact strength, the dynamic-mechanical rheological test (DMTA) and the surface contact angle analysis showed improvements in relation to pure HDPE when used methyl-modified pyrogenic silica as filler. This result suggests that the surface modification of pyrogenic silica with methylsilane groups results in a stronger interaction of this silica with the HDPE matrix. This effect was not observed for micron-sized silica gel, where modification with organosilanes was not sufficient to guarantee interfacial interaction with the HDPE matrix. [ABSTRACT FROM AUTHOR]

Abstract This paper describes the synthesis and characterization of epoxy resins based on (hexafluoroisopropylidene)diphenol (EFN) and p,p’-isopropylidenebisphenol (EBN), respectively and 4, 4’- (hexafluoroisopropylidene)dipthalic-imideamine (IMAM), a curing agent. The synthesized epoxy resins and IMAM curing agent were characterized by Fourier Transform Infrared (FTIR) and 1H Nuclear Magnetic Resonance (NMR) spectroscopy.13C NMR technique was also used to characterize IMAM. Study of curing behavior of EFN and EBN with stoichiometric amount of aromatic 4,4’-diaminodiphenylmethane (DDM), 4,4’-diaminodiphenylsulfone (DDS) and IMAM by using Differential Scanning Calorimetery (DSC) indicated that IMAM was least reactive curing agent towards both epoxy resins as compared to DDS and DDM. The investigation of thermal decomposition of the cured compounds by thermogravimetric analyzer (TGA) indicated the higher thermal stability of EFN and EBN resins initially with DDS and at elevated temperatures with IMAM. It was also observed that EFN resins were thermally more stable than EBN resins cured with corresponding curing agents.

AbstractAcid surface modified carbon nanotube (MCNT)-, Carbon nanotube (CNT)-filled fluoroelastomer (FE) and unfilled-FE were prepared (MCNT/FE, CNT/FE and FE). The compounds were subjected to thermogravimetric analysis (TGA) and heat air aging, and characterized by Energy Dispersive X-Ray (EDX). Results showed that MCNT improved the thermal properties of FE, resulting in a larger amount of FE and char remaining in the temperature range of 400-900 °C relative to unfilled FE and CNT/FE. The MCNT/FE TGA curve shifted towards higher temperatures compared to CNT/FE and FE. The same results also revealed that higher percentages of FE were undegraded or less degraded especially near MCNT in the temperature range of 400-540 °C. Energy Dispersive X-Ray (EDX) results indicated that the percentage of carbon and fluorine in the residue of TGA scans, up to 560 °C, of MCNT/FE were the same as CNT/FE, and were higher than FE. EDX results of TGA residue (run up to 900 °C) showed that most of the undegraded FE, which was not degraded at temperatures below 560 °C, was degraded from 560 °C to 900 °C in both MCNT/FE and CNT/FE, with the char in MCNT/FE being more than that in CNT/FE. EDX analysis of thermal aged specimens under air showed that, with increasing aging time, a greater percentage of C, O and F was lost from the surface of filler/FE and FE. The order of element loss after 24 hour aging time was: MCNT/FE > FE > CNT/FE.

Abstract Packages are essential for the food processing industry. Among the innovative alternatives there is antimicrobial packaging, which aims to reduce or inhibit microbial growing on the food surface. One potential to produce this type of package is poly(3-hydroxybutyrate)-PHB additivated with canola oil. In this work, films of PHB additivated with canola oil were produced in different compositions. Mid-infrared records, tensile mechanical testing and thermal analyses were performed on the films. The results of the mechanical tests indicated that the addition of canola oil to the polymeric matrix of PHB increases the material flexibility. The thermal analyses results showed that the addition of canola oil changes the thermal properties of PHB, such as the melting and crystallization temperatures, maximum crystallization rate and relative crystallinity. The knowledge of these properties is fundamental for the manufacturing process of polymeric materials, due to the specifications required for these materials in the intended applications.

A systematic study of solid state polymerization (SSP), concerning the melt extruded blend of poly(ethylene terephthalate)/polycarbonate (catalyzed PET/PC, 80/20 wt %), as a function of temperature range (180-190°C) for a fixed time (6 h) is presented. The materials obtained were evaluated by differential scanning calorimetry (DSC), thermogravimetry/derivative thermogravimetry (TG/DTG), optical microscopy (OM) and intrinsic viscosity (IV) analysis. After SSP, at all reaction temperatures, PET glass transition and heating crystallization temperatures slightly decreased, melting temperature slightly increased, while degree of crystallinity was practically invariable. The DTG curves indicated that, at least, three phases remained. The OM images revealed that the morphology is constituted of a PET matrix and a PC dispersed phase. In the interfacial region we noticed the appearance of structures like bridges linking the matrix and the dispersed domains. These bridges were correlated to the PET/PC block copolymer obtained during blending in the molten state. IV increased for all polymerization temperatures, due to the occurrence of PET chain extension reactions - esterification and transesterification. The IV range for bottle grade PET was achieved.

The aim of this study was to investigate the characterization of starch from Cissus simsiana Roem. & Schult. roots. The starch was extracted by steeping, wet grinding and sedimentation processes and its yield was calculated. Isolated starch was then characterized for chemical composition, morphology and granules size distribution, X-ray diffraction, mid-infrared spectra, swelling powder and solubility, pasting and thermal properties and clarity and syneresis behavior. The starch yield, based on starch presence in the root that can be isolated, were between 13.68% with 3.12 10-3 mg/g of carotenoids. C. simsiana granules were predominantly ellipsoids with 50-60 mm length and 20-30 mm wide. They exhibited B-type X-ray diffraction pattern with 41.2% of crystallinity, apparent amylose content of 26.2% and presented similar mid-infrared spectra to other starches. Onset and peak gelatinization temperatures were 64.2 and 68.56°C, respectively, and gelatinization enthalpy was 19.2 J/g. The apparent viscosity profile was comparable to cassava starch, but with higher peak viscosity (6500 cP), lower set back viscosity (600 cP) and less clear gel showing syneresis.

Poly(lactic acid)/Somasif fluoromica nanocomposites were prepared by melt blending and their thermal properties investigated by DSC, TGA and DMA. Three different types of synthetic mica (Somasif ME-100, Somasif MAE and Somasif MPE) were used at different contents (2.5, 5.0 and 7.5 wt %). The melt blending of PLA and these micas is characterized by a considerable reduction in the matrix molecular weight, which decreases when the nanofiller content is increased. For all nanocomposites, the thermal stability increases when mica is added to the polymer, with the Somasif MPE, producing the highest increase of the degradation temperature and highest reduction of Tg.

This paper aims to conduct a comparative analysis of composite materials subjected to apparently density tests and thermal tests. It will be made three samples. These materials will have as polymer matrix polyurethane (PU) with base of castor beans. A sample will be done with pure PU and the other two will be reinforced with sawdust and other wood-shaving in the proportion of 20% of the body made of pure PU. The PU was obtained commercially, while the wood was recycled from the tailings joinery. Through the thermal tests, it became possible to evaluate the behavior of its thermal properties. The fabrications of composites were made in metallic molds. With the study, we concluded that the materials reinforced with wood have a lower thermal conductivity and they are more apt to use as thermal insulation. [ABSTRACT FROM AUTHOR]

The solid state polymerization (SSP) of PET/PC reactive extrusion blends - with and without cobalt catalyst - at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's Tg, Tch, Tm and Xc.. The melt flow rate (MFR) decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions - esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's Tg to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

Composites of recycled high density polyethylene (HDPE-R) and coffee dregs (COFD) were elaborated. The blends were made at the proportions of 100-0, 90-10, 80-20, 70-30, 60-40, 50-50 and 40-60% polymer-filler ratio. The materials were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry/derivative thermogravimetry (TGA), and compressive resistance test. The compounding was done using a two-stage co-kneader system extruder, and then cylindrical specimens were injection molded. All composites had a fine dispersion of the COFD into the polymeric matrix. The composites degraded in two steps. The first one was in a temperature lower than the neat HDPE, but higher than the average processing temperature of the polymer. The melting temperature and the degree of crystallinity of the composites resulted similar to the neat HDPE ones. The compressive moduli of the composites resulted similar to the neat polymer one. The results show that these composites have interesting properties as a building material.

A series of novel polyamide-ethers (PAEs) based on bis-imidazole containing bulky aryl pendant groups was prepared by direct polycondensation of a diamine, 4-(1-(4-(4-(2-(4-aminophenyl)-4,5-diphenyl-1H-imidazol-1-yl)phenoxy)phenyl)-4,5-diphenyl-1H-imidazol-2-yl)benzenamine (DABI), and various dicarboxylic acids. All the resulting polyamide-ethers were amorphous with inherent viscosities ranged from 0.52 to 0.61 dL/g and were readily soluble in many organic solvents which could be solution-cast into transparent and tough films. The glass transition temperatures (Tg) of these polymers were affected considerably by their chemical structure and ranged from 230 to 310 ºC. They had useful levels of thermal stability associated with relatively high temperatures of 10% weight loss (T10) in the range of 329-399 ºC in air atmosphere.

In this study, it is investigated the synthesis and characterizations of polymerizable vinyl sugars. Carbohydrate containing polymers were synthesized via free radical polymerization. Thermal behavior of polymer derivatives was analyzed by using DSC and TG. Molecular weight dispersion of polymer derivatives was also analyzed with GPC. Molecular structures were analyzed by FT-IR and 1H-NMR spectrophotometer. We found that molecular weight of copolymers could effect to the thermal stability. According to TG data related to the copolymers, molecular weight of polymers increased while the thermal stability decreased. Thermogravimetric analysis of polymers also investigated. The apparent activation energies for thermal degradation of carbohydrate containing polymers were obtained by integral methods (Flynn - Wall - Ozawa, Kissinger - Akahira - Sunose, and Tang).

Foram estudadas as propriedades térmicas e mecânicas de compósitos de polipropileno, virgem e reciclado, reforçados com 30% em massa de fibras residuais de sisal, assim como o perfil de processamento e a morfologia da matriz polimérica. Para tanto, foram determinadas a resistência à tração, o módulo de Young, alongamento na ruptura, e energia de impacto. As amostras também foram caracterizadas por MEV, DMTA e TG. Para ambos os compósitos de polipropileno, virgem e reciclado, com a adição das fibras, o alongamento na ruptura mostrou uma queda significativa, enquanto que a resistência à tração não sofreu grandes variações. Houve um aumento significativo nos valores de tração na ruptura e de energia de impacto com a adição das fibras de sisal na matriz de polipropileno. As análises térmicas mostraram ligações secundárias, como as ligações polares, entre as fibras e a matriz, concordando com o comportamento mecânico dos compósitos. Constatou-se que a temperatura de transição vítrea não variou após a adição da fibra.The mechanical and thermal properties of virgin and recycled polypropylene composites reinforced with 30% by mass of residual sisal fibers were studied, in addition to an analysis of the extrusion process and morphology of the polymeric matrix. Tensile strength, Young's modulus, elongation at break, and impact energy were determined. The samples were also characterized by SEM, DMTA and TG analyses. Elongation at break of the composites presented a significant decrease, while the tensile strength was not affected significantly by addition of sisal fibers. A significant increase was observed in the tension of rupture and in the impact energy of the composite reinforced with sisal fiber. The thermal analyses indicated secondary interactions, such as polar interactions, between the fibers and the matrix, consistent with the mechanical behavior of the composites. The glass transition temperature has not changed after fiber addition.

Argilas bentoníticas natural e purificada (AN e AP) e montmorilonita (MMT), modificadas organicamente com os sais alquil amônio (A), alquil fosfônio (F) e com uma mistura de ambos (A e F), foram incorporadas, em teor de 1% em massa, ao PET pelo processo de fusão. Os híbridos obtidos foram caracterizados por difratometria de raios X (DRX), termogravimetria (TG), calorimetria exploratória diferencial (DSC) e microscopia eletrônica de transmissão (MET). Nanocompósitos com morfologia intercalada ordenada e intercalada desordenada/esfoliada foram obtidos quando manufaturados com as argilas organofilizadas com sal amônio e com a mistura dos sais amônio e fosfônio. A incorporação das argilas organofilizadas com o sal fosfônio ao PET não resultou na formação de nanocompósitos. As argilas organofílicas ANOA, APOF e MMTOF, quando misturadas ao PET, provocaram aumento da sua estabilidade térmica, além de atuarem como agentes nucleantes heterogêneos para o referido polímero, aumentando sua temperatura de cristalização. Este resultado é significativo do ponto de vista industrial, pois a baixa velocidade de cristalização do PET dificulta seu uso na preparação de artefatos injetados. Além disso, como as argilas bentoníticas fornecidas por empresa local apresentaram comportamento semelhante ao da montmorilonita importada, o uso dessa matéria-prima de menor custo, modificada com tecnologia nacional, pode ser uma alternativa atraente para aplicações do PET moldado por injeção onde o custo é um fator primordial.Montmorillonite (MMT), natural (AN) and purified (AP) bentonite clays modified with alkyl ammonium (A), alkyl phosphonium (F) and a mixture of both (A and F) salts were incorporated (1% w/w) into PET by melt blending. The hybrids thus obtained were characterized by XRD, TG, DSC and TEM. Nanocomposites having intercalated ordered structures and intercalated disordered/exfoliated structures were obtained with the clays modified with the ammonium and the mixture of ammonium and phosphonium salts, respectively. A nanocomposite was not obtained with the addition of 1% w/w of an alkyl phosphonium modified clay into PET. The organoclays ANOA, APOF and MMTOF, when added to PET not only led to an increase in its thermal stability but also acted as heterogeneous nucleating agents, increasing its crystallization temperature. This result is industrially significant as the low crystallization rate of PET makes its use difficult in preparing injected goods. Besides, as the behaviour of the bentonite clays supplied by a local industry was similar to that of the imported montmorillonite, the use of this raw material of lower cost, modified with national technology, can be an attractive technology for injection molded PET applications, where cost is of utmost importance.

O PHB (Poli-3-hidroxibutirato) é um termoplástico biodegradável sintetizado por fermentação submersa a partir de matérias-primas renováveis. A utilização de fibras naturais tem sido pesquisada visando melhorar as propriedades e reduzir o custo do PHB. O objetivo deste trabalho foi o estudo das propriedades mecânicas (resistência à tração), térmicas (Análise termogravimétrica,TGA, e Calorimetria Exploratória Diferencial, DSC) e reológicas (torque em câmera de mistura e Índice de Fluidez) do PHB e de compósitos de PHB/pó de madeira processados e irradiados. Foram preparados compósitos com concentrações de PHB/pó de madeira de 90/10, 80/20 e 70/30 (m/m). Os materiais foram processados através das seguintes etapas de processamento: calandragem, fragmentação, extrusão, granulação, secagem e moldagem por injeção para confecção dos corpos de prova. A incorporação do pó de madeira aumentou o grau de cristalinidade e a temperatura de cristalização do polímero, e nos compósitos PHB/pó de madeira 80/20 e 70/30 a rigidez do material aumentou. A irradiação após o processamento (dose de 30 kGy) provocou aumento da rigidez do PHB puro e dos compósitos PHB/pó de madeira 90/10 e 80/20, embora outras propriedades tenham decrescido. O compósito PHB/pó de madeira 70/30 apresentou os melhores resultados em termos econômicos e de processamento.PHB (Polyhydroxybutyrate) is a biodegradable thermoplastic synthesized by submerse fermentation of renewable raw materials. The use of natural fibers has been largely researched to improve PHB properties, as well as reducing its cost. The purpose of this work was the study of the mechanical, thermal properties and rheological analyses (torque in mixer camera and melt flow index) of processed and irradiated PHB, as well as PHB/wood flour composites. PHB/wood flour composites were prepared with PHB/wood relation of 90/10, 80/20 and 70/30 (w/w). Both pure PHB and composites were processed through the following steps: calendering, milling, extrusion, second milling, drying and injection molding to make test specimens. Mechanical properties (strength resistance) and thermo analyses (Thermogravimetric Analysis, TGA and Differential Scanning Calorimeter, DSC) tests were carried out. The introduction of the wood flour increased both polymer crystallinity and crystallization temperature. The material stiffness increased in PHB/wood flour composites (80/20 and 70/30). The irradiation after processing in 30 kGy doses led to increased stiffness of pure PHB and PHB/wood flour composites (90/10 and 80/20) while other properties have decreased. The PHB/wood flour composite 70/30 showed the best results in terms of economy and processing.

A incorporação de lodo industrial (L) e fibra de crisotila (FC) na preparação de compósitos com resina poliéster (P) é uma possível alternativa para minimizar o acúmulo de resíduos sólidos. A caracterização dos compósitos estruturais com estes reforços indicou diminuição nos valores de densidade quando comparados com compósitos reforçados com fibra de vidro. Os valores máximo e mínimo de resistência ao impacto Izod, para formulações do tipo P/L/FC, foram 29,1 e 12,6 J.m-1. A incorporação de lodo contribuiu para o aumento da capacidade de isolamento térmico de compósitos com fibra de crisotila, além de preservar a estabilidade térmica da matriz polimérica. Os resultados indicaram que apesar de provocar perdas mecânicas, a incorporação de lodo em compósitos com matriz de poliéster resulta em laminados com densidade reduzida e baixa condutividade térmica.The incorporation of industrial sludge (L) and chrysotile fiber (FC) in the preparation of composites with polyester resin (P) is a possible alternative to minimize the accumulation of solid wastes. The characterization of the structural composites with these reinforcements indicated reduction in density values when compared with glass fiber reinforced composites The maximum and minimum values of Izod impact resistance for P/L/FC formulations were 29.1 and 12.6 J.m-1. The incorporation of sludge led to an increased thermal isolation capability for composites with crysotile fiber, also preserving the thermal stability of the polymeric matrix. The results indicated that although there are damages in mechanical properties, the incorporation of sludge in composites with polyester matrix results in mils with reduced density and low thermal conductivity.

In this work, a detailed chemical route to prepare thermally stable polyaniline (PANI)/carbon black (CB) composites is described. The syntheses were performed by chemical polymerization of aniline over CB particles, using different PANI/CB mass ratios. The thermal and electrical properties were characterized. Composites with mass ratio up to 65:35 (PANI:CB) showed excellent thermal stability maintaining their conducting properties when thermally treated at 230 °C for two hours, which is adequate to process these materials. Moreover, the results showed an important reduction in the surface area of the composites which have a good relationship with the improvement of the rheological properties in melt processing.

El presente trabajo tuvo como objetivo estudiar las propiedades funcionales y térmicas en carne de reineta (Brama australis) congelada, mediante los análisis de capacidad de retención de agua (CRA), capacidad formadora de gel (CFG), textura, capacidad emulsionante (CE) y calorimetría diferencial de barrido (DSC). Para este estudio se utilizaron filetes de reineta obtenidos y extraídos bajo las mismas condiciones, los cuales fueron trozados, envasados, congelados y almacenados a temperaturas de -18ºC y -30ºC durante 7 meses. Los resultados para todos los tratamientos térmicos empleados no mostraron diferencias significativas entre individuos. Para los pescados congelados a -18ºC y -30ºC, los valores de proteínas totales fluctuaron entre 23,5 ± 0,0 y 25,4 ± 1,0 % respectivamente. Para el caso de CRA los valores se encontraron en un rango de 0,45 ± 0,1 y 1,59 ± 0,0 g agua/ g proteínas. En cuanto a la CFG sólo hubo formación de gel para la reineta fresca, existiendo producción de agregados proteicos para las muestras almacenadas. Por otra parte los valores de CE fluctuaron entre 960 a 1400 g de aceite/g proteína, con una tendencia al aumento a medida que el tiempo de almacenamiento fue mayor. Para el caso del DSC los valores de temperatura de desnaturalización (Td) y entalpía de desnaturalización (?H) de miosina fluctuaron entre 39,2 ± 0,5 y 44,8 ± 0,8 ºC y entre 1,12 ± 0,3 y 0,52 ± 0,2 J/g. Para la actina los valores fluctuaron entre 71,0 0,6 y 75,3 ± 0,5 ºC y entre 0,5 ± 0,1 y 0,7 ± 0,1 J/g, la cooperatividad disminuyó a medida que pasó el tiempo, lo cual está mostrando un cierto grado de desplazamiento de las proteínas. Los valores encontrados para propiedades térmicas presentan una directa relación con respecto a los valores de propiedades funcionales estudiadas, presentando ambos una disminución en el tiempo.The objective of the present work was to study functional and thermal properties of reineta ( Brama australis) frozen meat, analysed by water retention capacity (WRC), gel forming capacity ( GFC), texture, emulsifying capacity and differential scanning calorimetry ( DSC). For this study, reineta fillets were obtained and extracted by the same conditions, and cutted, packaged, frozen and stored at -18ºC and - 30ºC for 7 months. The results obtained, showed that there were no signifficant differences in the responses to thermal treatment for all the specimens. For samples frozen at -18ºC and -30ºC, the protein contents were 23.5 + 0.0 and 25.4 + 1.0%, respectively. The WRC values were 0.45 + 0.1 and 1.59 + 0.0 g water/ g protein, respectively. The gel forming capacity was only present in the fresh samples, whereas the frozen stored ones only form protein aggregates. The emulsifying capacity was between 960 and 1400 g oil / g protein, and the storage time increased this value. The miosin denaturation temperature (Td) and denaturation enthalpy ( ?H), obtained by DSC, fluctuated between 39.2 + 0.5 to 44.8 + 0.8 ºC and 1.12 + 0.3 to 0.52 + 0.2 J/g, respectively. The actina values were between 71.0 + 0.6 to 75.3 + 0.5 ºC and between 0.5 + 0.1 to 0.7 + 0.1 J/g. Cooperativity decreased as the storage time increased. This is showing a certain degree of protein displacement. The values found by thermal analyses showed a direct relationship with the functional properties, both decreasing with storage time.

A condutividade térmica, a difusividade térmica e o calor específico, conhecidos como propriedades térmicas são as três propriedades físicas de um material mais importantes do ponto de vista de cálculos térmicos. Elas são essenciais na determinação dos parâmetros de resistência ao choque térmico em refratários e na determinação dos fatores de dissipação de calor em fornos e fornalhas. A condutividade térmica é um parâmetro importante em problemas envolvendo transferência de calor em regime estacionário, enquanto que a difusividade térmica é importante em estados não estacionários de troca de calor. O calor específico, propriedade importante em altas temperaturas, está associado ao consumo de energia durante o aquecimento. Normalmente essas três propriedades são determinadas separadamente por técnicas e equipamentos individuais. Hoje são conhecidos vários métodos para a determinação da condutividade térmica e difusividade térmica. Recentemente, os métodos transientes de troca de calor têm sido os métodos preferidos na determinação das propriedades térmicas de materiais. Neste trabalho é feita uma descrição e uma análise crítica de um dos métodos mais utilizados na determinação das propriedades térmicas de materiais cerâmicos: o método do fio quente. Com este método é possível determinar simultaneamente, a partir do mesmo transiente térmico experimental, as três propriedades térmicas. Resultados numéricos são também apresentados.Thermal conductivity, thermal diffusivity and specific heat, namely as the thermal properties, are the three most important physical properties of a material that are needed for heat transfer calculations. They are essential in thermal shock parameters determination or in calculations of heat dissipation factors in furnaces and kilns. Thermal conductivity is an important parameter in problems involving steady state heat transfer, while the thermal diffusivity is important in non-steady heat transfer calculations. The specific heat is also a decisive property of ceramic materials in high temperature applications, and it is associated with heat consumption during the heating process. Normally these properties are determined separately by individual techniques and apparatus. Nowadays, several different techniques for the determination of the thermal diffusivity and thermal conductivity may be found in the literature. Recently, transient techniques have become the preferable way for measuring thermal properties of materials. In this work it is presented a description as well as a critical analysis of one experimental technique employed worldwide for thermal properties measurements of ceramic materials: the hot wire technique. With this technique it is possible to determine simultaneously from the same temperature transient the three thermal properties. Numerical results are also presented.

A natureza da estrutura molecular dos plásticos torna as propriedades desses materiais fortemente dependentes da temperatura. A condutividade térmica, difusividade térmica e o calor específico, conhecidos como propriedades térmicas, são as três propriedades físicas mais importantes de um material em cálculos de transferência de calor. Valores confiáveis dessas propriedades são essenciais em polímeros, tanto em problemas envolvendo estado estacionário como em estado não estacionário de troca de calor. Hoje, várias técnicas diferentes para a determinação da condutividade térmica e difusividade térmica podem ser encontradas na literatura. Neste trabalho, a técnica de fio quente paralelo é empregada na determinação experimental das propriedades térmicas de polímeros. Três polímeros semi-cristalinos (PEAD, PEBD e PP), e dois polímeros amorfos (PS e HIPS) foram selecionados para este trabalho. As medidas experimentais são feitas desde a temperatura ambiente até a, aproximadamente, 50 ºC acima da temperatura de fusão. As amostras são preparadas pelo processo de extrusão, partindo-se do pó ou "pellets" do polímero no estado sólido. Um molde especial de aço inoxidável, em forma de paralelepípedo retangular, provido de isoladores cerâmicos entre o fio quente, o termopar e o próprio molde é utilizado para armazenar a massa polimérica fundida, cujas propriedades térmicas serão medidas. Os resultados experimentais obtidos são comparados com dados disponíveis na literatura e com dados fornecidos pelos fabricantes. Uma análise crítica desta metodologia mostra as vantagens e desvantagens desta técnica experimental em relação à técnica de pulso de energia.The nature of the molecular structure of the plastics makes the properties of such materials markedly temperature dependent. Thermal conductivity, thermal diffusivity and specific heat, namely the thermal properties, are the three most important physical properties of a material that are needed for heat transfer calculations. Reliable thermal properties values are essential for polymers, both in steady and non-steady state situations. Nowadays, several different techniques for the determination of the thermal diffusivity and thermal conductivity may be found in the literature. In this work, the hot wire parallel technique is employed in the experimental determination of the thermal properties of polymers. Three semi-crystalline polymers (HDPE, LDPE and PP), and two amorphous polymers (PS and HIPS) were selected for this work. Samples are prepared through the extrusion process starting from the powder or pellets of the solid polymer. A special mould of stainless steel in the shape of a rectangular parallelepiped provided with ceramic insulators between the hot wire, thermocouple and the mould is employed to store the melt extruded polymer whose thermal properties will be measured. Measurements are carried out from room temperature up to approximately 50 ºC above the melting point. Experimental results obtained are checked against data found in literature and those ones furnished by the manufacturers. A critical analysis of this method shows the advantages and disadvantages of this technique when compared with the laser flash technique.

A condutividade térmica, a difusividade térmica e o calor específico, conhecidas como propriedades térmicas são as três propriedades físicas mais importantes de um material do ponto de vista de cálculos térmicos. Essas propriedades são observadas quando calor é adicionado ou removido do material, e se tornam importantes em qualquer projeto que precise funcionar em qualquer ambiente térmico. A condutividade térmica é uma das propriedades físicas mais importantes de um material. A sua determinação experimental apresenta algumas dificuldades e requer alta precisão na determinação dos fatores necessários para o seu cálculo. A difusividade térmica pode ser medida mais facilmente e com maior precisão do que a condutividade térmica. Por essa razão, muitos pesquisadores preferem medir a difusividade, e a partir dela calcular a condutividade térmica do material. Hoje são conhecidos vários métodos para a determinação da condutividade térmica e difusividade térmica de um material. Recentemente, os métodos transientes de troca de calor têm sido os métodos preferidos na determinação das propriedades térmicas de materiais. Neste trabalho é feita uma descrição e uma análise crítica de um dos métodos mais utilizados na determinação das propriedades térmicas de materiais cerâmicos: o método de pulso de energia. Resultados numéricos são também apresentados.Thermal conductivity, thermal diffusivity and specific heat, namely as the thermal properties, are the three most important physical properties of a material that are needed for heat transfer calculations. Those properties are observed when heat is added or removed from a material, and they become important in any design that must function in any thermal environment. Thermal conductivity is one of the most important physical properties of a material. However, its experimental evaluation may presents some specific troubles, and high precision in the determination of the factors involved in its calculation is required. The thermal diffusivity can be measured more easily and accurately than the thermal conductivity. For this reason, many researchers prefer to measure the thermal diffusivity and then to derive the thermal conductivity. Nowadays, several different techniques for the determination of the thermal diffusivity and thermal conductivity may be found in the literature. Recently, transient techniques have become the preferable way for measuring thermal properties of materials. In this work it is presented a description as well as a critical analysis of one experimental technique employed worldwide for thermal properties measurements of ceramic materials: the laser flash technique. Numerical results are also presented.

A técnica de fio quente paralelo normalizada para a determinação da condutividade térmica de materiais cerâmicos foi empregada na determinação das propriedades térmicas de polímeros. As amostras foram preparadas em forma de paralelepípedos retangulares, com dimensões de (230x80x30)mm. Neste trabalho, a condutividade térmica e o calor específico foram simultaneamente determinados a partir do mesmo transiente térmico experimental e a difusividade térmica foi calculada a partir dessas duas propriedades. Cinco diferentes polímeros com diferentes estruturas a temperatura ambiente foram selecionados neste trabalho. Os cálculos foram feitos utilizando-se um método de ajuste por regressão não linear, de tal maneira que todos os pontos experimentais obtidos são considerados nos cálculos dessas propriedades térmicas. O equipamento utilizado neste trabalho é totalmente automatizado. A reprodutibilidade dos resultados foi muito boa com respeito à condutividade térmica, obtendo-se um desvio máximo de apenas 0,5% entre os valores máximo e mínimo para todas as amostras ensaiadas, mesmo introduzindo propositadamente alguns defeitos no arranjo experimental, em relação ao modelo teórico. Todavia, pequenos desvios do modelo teórico podem causar drásticas influências nos valores de calor específico, obtendo-se desvios de até 32% em relação ao arranjo experimental correto. Os resultados experimentais foram então comparados com aqueles encontrados na literatura. As discrepâncias observadas entre alguns desses valores podem estar associadas ao grau de cristalinidade ou à história térmica da amostra, ficando assim mostrada a aplicabilidade desta técnica na determinação das propriedades térmicas de polímeros.The hot wire parallel technique standardized for determining thermal conductivity of ceramic materials was employed in the determination of thermal properties of polymers. Samples were prepared in shape of rectangular parallelepipeds. In this work the thermal conductivity and the specific heat were simultaneously determined from the same experimental thermal transient, and the thermal diffusivity is derived from these properties. Five different polymers with different structures at room temperature were selected and measurements were carried out at room temperature. A non-linear least squares fitting method was employed in the calculations, so that all the experimental points obtained are considered in the thermal properties calculations. The apparatus used in this work is fully automatic. The reproducibility is very good with respect to thermal conductivity, even with a defective experimental arrangement with respect to the theoretical model. However, deviations from the theoretical model causes severe influence on the specific heat values and consequently in the thermal diffusivity. Experimental results were compared with those available in literature, showing the applicability of this technique in the determination of thermal properties of polymers.

Quenched thin films (about 100 microns thick) of high-density polyethylene (HDPE) / oligobetapinene (OBP) blends were prepared by melt mixing with the amount of OBP varying from 0 to 40%. The results of CO2 permeation, thermal behavior and morphology are reported. From -130 to -100 °C we observed two peaks in DSC measurements, the lower one being ascribed to g-transition of HDPE. The upper one attributed to Tg which was shift at high contents of OBP. The OPB molecules also displayed another transition at higher temperatures. The normalized degree of crystallinity of HDPE remained constant while the overall crystallinity of the blends was reduced in all blends. We have hypothesized that three distinct phases coexist, viz. a HDPE-amorphous phase with some amount of OBP molecules, OBP-amorphous phase with polyolefin and HDPE-crystalline phases. The permeation test revealed a decrease in permeability to CO2 independent of the amount of OBP in the blends. The reduction of gas permeation could be explained mainly by the rigidity of the OBP rich phase that has counterbalanced the decrease of overall crystallinity of the film blends.

The hot wire technique is considered to be an effective and accurate means of determining the thermal conductivity of ceramic materials. However, specifically for materials of high thermal diffusivity, the appropriate time interval to be considered in calculations is a decisive factor for getting accurate and consistent results. In this work, a numerical simulation model is proposed with the aim of determining the minimum and maximum measuring time for the hot wire parallel technique. The temperature profile generated by this model is in excellent agreement with that one experimentally obtained by this technique, where thermal conductivity, thermal diffusivity and specific heat are simultaneously determined from the same experimental temperature transient. Eighteen different specimens of refractory materials and polymers, with thermal diffusivities ranging from 1x10-7 to 70x10-7 m²/s, in shape of rectangular parallelepipeds, and with different dimensions were employed in the experimental programme. An empirical equation relating minimum and maximum measuring times and the thermal diffusivity of the sample is also obtained.

Thermal diffusivity is a material physical property important in all problems involving non-steady state heat transfer calculations, being a decisive parameter in the response of materials subjected to thermal shock. In this work it is presented a fundamental study related to how the phase transitions may influence the thermal diffusivity behaviour as a function of temperature in the phase transforming SiO2. The experimental technique employed was the flash thermal diffusivity technique, and measurements were carried out from 100 ºC up to approximately 1200 ºC. It was found a strong dependence on the thermal diffusivity with the high and low temperature forms of the quartz and cristobalite phases.

This paper describes a low-cost microprocessed instrument for in situ evaluating soil temperature profile ranging from -20.0°C to 99.9°C, and recording soil temperature data at eight depths from 2 to 128 cm. Of great importance in agriculture, soil temperature affects plant growth directly, and nutrient uptake as well as indirectly in soil water and gas flow, soil structure and nutrient availability. The developed instrument has potential applications in the soil science, when temperature monitoring is required. Results show that the instrument with its individual sensors guarantees ±0.25°C accuracy and 0.1°C resolution, making possible localized management changes within decision support systems. The instrument, based on complementary metal oxide semiconductor devices as well as thermocouples, operates in either automatic or non-automatic mode.Este artigo descreve um instrumento microprocessado de baixo custo para avaliação in situ da temperatura em perfil de solo na faixa de -20,0°C a 99,9°C com armazenagem de dados de até oito profundidades, de 2 a 128 centímetros. A temperatura do solo é de grande importância para o crescimento de plantas, absorção de nutrientes, fluxo de gases e estrutura. O instrumento desenvolvido encontra várias aplicações na área da ciência do solo, onde o monitoramento de temperatura do solo é requerido. Resultados mostram que a caracterização do instrumento e seus sensores individuais garantem uma acurácia de ±0,25°C e uma resolução de 1,0°C. Também proporciona a produtores ou pesquisadores a oportunidade do manejo localizado para sistemas de tomada de decisão. O instrumento é baseado em dispositivos semicondutores com tecnologia de óxido metálico complementar e termopares. E pode operar tanto no modo manual quanto no modo automático.

A técnica da célula fotoacústica aberta é uma metodologia fototérmica conhecida, baseada no monitoramento do aumento e da diminuição da temperatura das amostras foram realizadas para obter as propriedades termofísicas, difusividade térmica α e capacidade térmica específica ρC, respectivamente, para caracterizar cerâmicas vermelhas em função da temperatura de queima. Posteriormente, através de uma relação matemática simples, a condutividade térmica κ foi avaliada. Valores compreendidos entre 0,0013 cm²/s a 0,0036 cm²/s e 1,05 a 1,51 J/cm³K foram obtidos para a difusividade térmica e capacidade térmica específica, respectivamente. Fases cristalinas foram identificadas por difração de raios X, mostrando que a caulinita é a fase predominante. Além disso, a relação entre propriedades térmicas e difratograma foi apresentada e comprovada.The open photoacoustic cell (OPC) technique and another well known photothermal set up based on the measurement of the increase and decrease temperature of heated samples were carried out to obtain the thermophysical characteristics, thermal diffusivity α and specific heat capacity ρC, respectively, are arranged in order to characterize red ceramics as a function of firing temperature. Thereafter, by means of a simple mathematical relation, we could evaluate the thermal conductivity κ. Values ranging from 0.0013 cm²/s to 0.0036 cm²/s and 1.05 to 1.51 J/cm³K were obtained for thermal diffusivity and specific heat capacity, respectively. Crystalline phases were identified by X-ray diffraction, showing that kaolinite was the predominant phase. Furthermore, the relationship between thermal properties and diffractogram was presented and verified.

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a methodology to quantify the stored heat in a steel ladle in a Steelmaking Shop in order to calculate the heat input required by the drying and heating process by using a natural gas heater. The current situation is mathematically modeled in order to obtain the combustion energy balance. Through finite element modeling in transient state it is possible to obtain the thermal profile, measure process losses and propose adjustments to the drying and heating curves. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses a study which examines the impact of the binder, which is the calcium aluminate cement, on alumina-magnesia castables. It cites the expansive behavior of alumina-magnesia castables when treated at high temperatures and the changes in the properties of such materials including volumetric stability if the binders are changed. Moreover, the study reveals that the binder systems can be employed in designing the expansion of these castables.

The article analyzes the measurements of thermal and structural properties of red ceramics. It focuses on the usage of open photoacoustic cell (OPC) technique to obtain the thermophysical characteristics to evaluate the thermal conductivity of the red clay. It presents and verifies the relationship between thermal properties and diffractogram.