Pernambuco Institute of Technology

Recife, Brazil

Pernambuco Institute of Technology

Recife, Brazil
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Vitorino M.B.C.,Federal University of Campina Grande | Reul L.T.A.,Federal University of Campina Grande | Carvalho L.H.,Federal University of Campina Grande | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology
AIP Conference Proceedings | Year: 2015

The present work studies the thermal properties of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermo-plastic obtained from renewable resources through low-impact biotechno-logical process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree. PHB is a highly crystalline resin and this characteristic leads to suboptimal properties in some cases. Consequently, thermal properties, in particular those associated with the crystallization of the matrix, are important to judge the suitability of the compounds for specific applications. PHB/babassu composites with 0-50% load were prepared in an internal mixer. Two different types of babassu fibers with two different particle size ranges were compounded with PHB and test specimens molded by compression. Melting and crystallization behavior were studied by differential scanning calorimetry (DSC) at heating/cooling rates between 2 and 30°C/min. Several parameters, including melting point, crystallization temperature, crystallinity, and rate of crystallization, were estimated as functions of load and heating/cooling rates. Results indicate that fibers do not affect the melting process, but facilitate crystallization from the melt. Crystallization temperatures are 30 to 40°C higher for the compounds compared with the neat resin. However, the amount of fiber added has little effect on crystallinity and the degree of crystallinity is hardly affected by the load. Fiber type and initial particle size do not have a significant effect on thermal properties. © 2015 AIP Publishing LLC.


Marinho V.A.D.,Federal University of Campina Grande | Carvalho L.H.,Federal University of Campina Grande | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology
AIP Conference Proceedings | Year: 2015

The present work studies the effect of water absorption on the performance of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree.Water resistance is an important characteristic of structural composites, that may exposed to rain and humid environments. Both water absorption capacity (water solubility in the material) and the rate of water absorption (controlled by the diffusivity of water in the material) are important parameters. However, water absorption per se may not be the most important characteristic, insofar as the performance and applications of the compounds. It is the effect of the water content on the ultimate properties that determine the suitability of the material for applications that involve prolonged exposure to water.PHB/babassu composites with 0-20% load were prepared in an internal mixer. Two different types of babassu fibers having two different article size ranges were compounded with PHB and test specimens molded by compression. The water absorption capacity and the kinetic constant of water absorption were measured in triplicate. Mechanical properties under tension were measured for dry and moist specimens with different amounts of absorbed water.Results indicate that the performance of the composites is comparable to that of the pure matrix. Water absorption capacity increases from 0.7% (pure PHB) to 4% (PHB/20% babassu), but the water diffusivity (4·10□8 cm2/s) was found to be virtually independent of the water absorption level. Water absorption results in moderate drop in elastic modulus (10-30% at saturation, according to fiber content) but has little effect on tensile strength and elongation at break. Fiber type and initial particle size do not have a significant effect on water absorption or mechanical properties. © 2015 AIP Publishing LLC.


Cipriano P.B.,Federal University of Campina Grande | De Sa M.D.,Federal University of Campina Grande | Andrade A.L.S.,Federal University of Campina Grande | De Carvalho L.H.,Federal University of Campina Grande | And 2 more authors.
AIP Conference Proceedings | Year: 2015

The present work deals with the thermal stability during and after processing of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree. PHB/babassu composites with 0, 5, 10 and 20% w/w load were prepared in a laboratory internal mixer. Two fractions of the mesocarp of babassu with different particle sizes were compounded with PHB and test specimens molded by compression. The effect of loading level and processing conditions on torque, temperature and mechanical energy dissipation were studied using a new engineering model. It was found that PHB degrades during processing at temperatures slightly above the melting point. To minimize thermal degradation stabilizer and chain extender additives were incorporated, with mixed results. These findings were confirmed by the dependence of the melt flow rate on the processing temperature. © 2015 AIP Publishing LLC.


Wellen R.M.R.,Federal University of Paraiba | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology | Rabello M.S.,Federal University of Campina Grande
AIP Conference Proceedings | Year: 2016

In this work compounds of poly(3-hydroxybutyrate) (PHB) and carbon black (CB) with CB content ranging between 0.5% and 10.0% were prepared in a laboratory internal mixer. The effect of heating and cooling rates on the crystallization of PHB/CB compounds was investigated by differential scanning calorimeter (DSC), and its morphology was analyzed by optical microscopy (OM). Several rates, ranging from 2 to 32°C/min, were utilized to analyze the phase change during heating/cooling/reheating cycles and several magnifications were applied during morphologic study of the spherulitic structure. The results showed that PHB and its compounds crystallize partially from the melt during cooling cycle and cold crystallizes partially on reheating, and that the relative amount of polymer crystallizing in each stage depends strongly on the cooling rate. The melting and cold crystallization temperatures as well as the rates of phase change were found to depend strongly of cooling and heating rates and of CB content. CB behaves as a nucleant promoting the melt and cold crystallization of PHB as well as increasing the number of spherulites. Optical microscopy images suggest that crystallization of PHB continues during storage for 24 hours, at ambient temperature. © 2016 Author(s).


Wellen R.M.R.,Federal University of Paraiba | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology
AIP Conference Proceedings | Year: 2016

In this work compounds of poly(3-hydroxybutyrate) (PHB) and carbon black (CB) with CB content ranging between 0.5% and 10.0% were prepared in a laboratory internal mixer. The effect of heating and cooling rates on the melt and cold crystallization of PHB/CB compounds was investigated by differential scanning calorimeter (DSC), and the dependence of the heating and cooling rate with crystallization time at a constant crystallinity level was correlated using the model proposed by Mo and collaborators. Mo model parameters are well behaved and may be correlated in terms of carbon black content and heating/cooling rate, allowing use of the model for arbitrary system/conditions (within the range tested and avoiding extremes). Ultimately, the success or failure of empirical correlation models depends on its intended use, and the acceptable level of discrepancy between predicted and experimental result, as verified in the present work, that the specific application may tolerate. © 2016 Author(s).


Wellen R.M.R.,Pernambuco Institute of Technology | Rabello M.S.,Federal University of Campina Grande | Fechine G.J.M.,University of Sao Paulo | Canedo E.L.,Pernambuco Institute of Technology
Polymer Testing | Year: 2013

This work is concerned with the melting behaviour and accuracy of differential scanning calorimeter (DSC) analyses of poly(3-hydroxybutyrate) (PHB), a semi-crystalline thermoplastic polymer completely biodegradable and biocompatible, and obtained from renewable resources. Melting parameters of PHB were determined for the first fusion event applying standard experimental procedures for thermal analysis, using heating rates ranging between 1 °C/min and 20 °C/min. The analyses of DSC energy flow scans showed a complex melting peak that may be resolved into three elementary peaks having different intensities at different melting temperatures. Peak temperatures depend on heating rate, while the total crystallinity detected was independent of the rate. A study of 24 DSC runs showed good temperature reproducibility (±0.5 °C), but poor reproducibility of mass crystallinity (±10%). © 2012 Elsevier Ltd. All rights reserved.


Wellen R.M.R.,Federal University of Paraiba | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology
Journal of Materials Research | Year: 2016

Three classical methods (Pseudo-Avrami, Ozawa, and Mo models) were used to correlate nonisothermal melt and cold crystallization kinetics data of neat poly(3-hydroxybutyrate) (PHB) and PHB/carbon black compounds, measured by differential scanning calorimetry. The applicability of the three models was tested comparing model predictions with experimental data. Results suggest that Pseudo-Avrami model fits the experimental data well. Ozawa model does not fit data well, as verified by the large uncertainties and unphysical values of the fitting parameters. Mo model may be considered adequate if moderately deviations could be tolerated. Datasets of all compositions are included as the Supplementary Information. © 2016 Materials Research Society.


Costa A.R.M.,Federal University of Campina Grande | Almeida T.G.,Federal University of Campina Grande | Silva S.M.L.,Federal University of Campina Grande | Carvalho L.H.,Federal University of Campina Grande | And 2 more authors.
Polymer Testing | Year: 2015

This contribution is concerned with degradation and chain extension in poly(butylene-adipate-terephthalate), PBAT, compounded in a laboratory internal mixer with an epoxydic chain extender additive. Weight-average mass change during melt processing was estimated from temperature-torque-time data recorded by the equipment. The effect of the additive was found to be strongly dependent on processing temperature, and weakly dependent on concentration. Molar mass more than doubled at 230°C with 2% additive. Long induction times and catastrophic failure to mix, occasionally observed with oligomeric additives processed in internal mixers, are discussed. Possible implementation of the procedure for real-time estimate of chain extension is also discussed. © 2015 Elsevier Ltd.All rights reserved.


Vitorino M.B.C.,Federal University of Campina Grande | Cipriano P.B.,Federal University of Campina Grande | Wellen R.M.R.,Federal University of Paraiba | Canedo E.L.,Federal University of Campina Grande | And 2 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2016

Poly(3-hydroxybutyrate) (PHB)/babassu compounds were prepared in a laboratory internal mixer with 10, 30, and 50 % by mass of fiber content. Nonisothermal melt crystallization behavior of PHB/babassu compounds was investigated using differential scanning calorimetry, and crystallization parameters were determined at cooling rates ranging between 2 and 32 °C min−1. Adding babassu fiber affected the melt crystallization behavior of PHB, and increasing filler content from 10 to 30 % has significant effects on the thermal characteristics of the system. Further increase in filler content from 30 to 50 % filler content has no effect on crystallization temperature and rate, but it has important positive consequences, once there is a considerably latitude in choosing the actual filler level in highly loaded PHB/babassu compounds without affecting processing characteristics. The melt crystallization kinetics of PHB/babassu compounds was analyzed by three empirical models widely used to represent nonisothermal polymer crystallization data: Pseudo-Avrami, Ozawa, and Mo. Kinetics analyses indicate that the Pseudo-Avrami model represented well the experimental data for both compounds in a wide interval of temperature, conversion, and cooling rates; the Ozawa model with two different sets of parameters, for low and high cooling rates, was found to correlate the data equally well, but over limited ranges of the variables, and the model proposed by Mo and collaborators did not adequately represent the experimental data for the systems and conditions tested. © 2016 Akadémiai Kiadó, Budapest, Hungary


Ferreira K.R.M.,Federal University of Campina Grande | Andrade D.L.A.C.S.,Federal University of Campina Grande | Canedo E.L.,Federal University of Campina Grande | Canedo E.L.,Pernambuco Institute of Technology | And 2 more authors.
Materials Science Forum | Year: 2015

In this study, the influence of type and amount of organoclay in the morphology of the polymer blend PP/EPDM is evaluated. Pure and filled mixtures were prepared by melt intercalation in an internal mixer. The morphology of the hybrids was evaluated by X-ray diffraction and scanning electron microscopy. The results showed that the incorporation of the organophyllic clay to the PP/EPDM blend resulted in new interfacial interactions between components, which contributed to a decrease in the size of the dispersed phase and the compatibility of the blends. Therefore, organoclays may be employed to compatibilize polymeric blends, replacing conventional compatibilizers. © (2015) Trans Tech Publications, Switzerland.

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