Abstract In this paper, the crystallization, fusion, and activation energy (Ea) of PBT/TiO2 were thoroughly evaluated using DSC. Increasing the rates shifted the peaks of melt crystallization to lower temperatures while the fusions were almost unaffected. TiO2 hindered the melt crystallization of PBT and lower crystallization rates, i.e., CMAX and K’ were acquired, in general, the crystallinity degree (Xc) was 4% higher in PBT/TiO2 which is in the marginal error. Pseudo-Avrami and Mo models were applied to evaluate the melt crystallization kinetics; both fitted the melt crystallization quite well; deviations were observed at the beginning and the crystallization end most due to the nucleation and spherulites impingement during the secondary crystallization. Ea was evaluated using the Friedman model, considering the values of Ea less energy has to be removed from PBT/TiO2 when compared to PBT, specifically at 1% of TiO2.

Abstract In this work eggshell membrane was added as biobased curing catalyst to epoxy (DGEBA), for comparison purposes the synthetic catalyst DEH 35 data was reported, the curing of compounds was followed through differential scanning calorimetry (DSC) under dynamic conditions and their kinetics were modeled using Kissinger, Friedman, Friedman model based and Málek approaches. From evaluated Ea and l n A two steps of curing were verified, for the synthetic catalyst compound (S5) Ea abruptly increased for the degree of conversion α > 0.7 the opposite trend was observed for the eggshell membrane compound (M10). It is supposed for S5 Ea increases due to the competitive reactions leading to viscosity increase until reach the solid phase with decrease of the reactive groups availability, hampering the cross-linking, whereas for M10 Ea decreases at α > 0.7, hence invalidating the Kissinger model which assumes constant Ea.

Abstract Researches of polymer blends based on biological and biodegradable polymers appear as a viable alternative to develop environmentally friendly materials. Therefore, the aim of this research was to produce compounds made with biological polyethylene, i.e., Biopolyethylene, Bio-PE, added to the biodegradable Polycaprolactone (PCL) and functionalized by the copolymer of polyethylene grafted with acrylic acid (PEgAA), to obtain better mechanical properties and toughen Bio-PE. Compounds were processed in a co-rotating twin screw extruder and sample tests were injection molded. The compositions investigated were: Bio-PE/PCL at 90/10, 80/20 and 70/30 wt.% without compatibilizer and upon addition of 10 phr (parts per hundred of resin) of PEgAA. The blends were characterized by X-ray diffraction (XRD), impact strength, heat deflection temperature (HDT) and scanning electron microscopy (SEM). Through XRD, it was observed that addition of PCL and PEgAA did not significantly change Bio-PE diffraction patterns. Impact strength data showed that the blends presented a tougher behavior upon addition of PCL and PEgAA. The HDT of compatibilized blend with 20wt.% of PCL was slightly higher. SEM images of compatibilized blends showed lower average particle diameters as well as absence of coalescence and aggregates.

Abstract Blends of Polystyrene (PS) and Poly(ε-caprolactone) (PCL) were twin screw extruded, two PSs, with low and high melt flow rate (MFR) were used and their feasibility within PCL investigated by means of torque rheometry, mechanical tests, heat deflection temperature (HDT) and scanning electron microscopy (SEM); predictive models were utilized to evaluate interfacial adhesion in PS/PCL blends. Results show that no decreasing was verified in torque rheometry plots suggesting thermally stable blends; elastic modulus decreased and elongation at break increased in PS/PCL blends compared to neat PS. PS/PCL blends with low MFR PS and higher PCL amount are more thermodynamically stable. Higher HDT was verified in PS/PCL blends. The trends observed applying predictive models are indicative of poor adhesion between PCL and PS, agreeing with coalescence and phase segregation as verified in SEM images. PS/PCL systems with higher MFR PS presented the best results.

In this work, compounds based on two grades of polypropylene (PP), i.e., PP H503 or PP H103 with residues of Big bag fabrics (RBB) were processed in a corrotational twin screw extruder with RBB content ranging from 10% to 50% of the weight. Then, their thermal properties were investigated through Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG); mechanical by tensile and impact; thermomechanic by heat deflection temperature (HDT); and their morphology by Scanning Electron Microscopy (SEM). With the aim to add maximum RBB content without considerable damage to the properties of neat PPs, it was observed that addition of 10%, 30% and 50% of RBB did not significantly interfere in the PP matrices, being the compound PP + 30% RBB which one presented more successful properties, leading to reused compounds with higher performance and lower costs at same time.

RESUMO Nanomateriais vem atraindo bastante atenção nos últimos anos em virtude das suas propriedades que permitem aplicações em diversas áreas como: química, física, medicina, fármacos e engenharias. No universo dos nanomaterias, as nanopartículas de prata (AgNPs) tem despertado o interesse de vários pesquisadores devido ao seu potencial bactericida. Estudos recentes correlacionaram a eficácia da atividade antimicrobiana com a razão superfície-volume, morfologia, polidispersividade, tamanho de partícula e estabilidade das AgNPs. Este trabalho teve como objetivo compreender a influência do borohidreto de sódio (NaBH4) e do peróxido de hidrogênio (H2O2) nas propriedades das AgNPs. A síntese das AgNPs foi realizada através da redução química de íons de prata com NaBH4, na presença de H2O2 e Citrato de Sódio (SCT). Para determinar a influência causada pelo H2O2 e NaBH4, foram empregados diferentes variações de concentrações e volumes e ao resultado foi aplicado o Teste de Fisher para determinar a significância entre essas variáveis. As amostras foram caracterizadas por Espalhamento Dinâmico de Luz (DLS) e Potencial Zeta. Como resultado, o Teste de Fisher em conjunto com os valores obtidos de tamanho de partícula, estabilidade e polidispersividade determinaram variáveis estatisticamente iguais, ou seja, as variáveis que não influenciam estatisticamente na formação das partículas, bem como, a influência causada pela variação do H2O2 e do NaBH4 nas propriedades das AgNPs. Por fim, a variação da concentração de NaBH4 e volume de H2O2 causam efeitos sob o diâmetro, estabilidade e polidispersividade de AgNPs os quais foram estudados e aqui estão descritos.

ABSTRACT Nanomaterials has attracted a lot of attention in recent years due to its properties that allow applications in several areas such as chemistry, physics, medicine, pharmaceuticals, and engineering. In the nanomaterial universe, silver nanoparticles (AgNPs) have awakened the interest of several researchers because of their bactericidal potential. Recent studies have correlated the efficacy of antimicrobial activity with the surfacevolume ratio, morphology, polydispersity, particle size and AgNPs stability. This work aimed to understand the influence of sodium borohydride (NaBH4) and hydrogen peroxide (H2O2) on the AgNPs properties. The synthesis of AgNPs was performed by chemical reduction of silver ions with sodium borohydride in the presence of hydrogen peroxide and sodium citrate. To determine the influence caused by H2O2 and NaBH4, different concentrations and volume variations were used and a Fisher’s exact test was applied to determine the significance between variables. The samples were characterized by Dynamic Light Scattering (DLS) and Zeta Potential. Results determined that the Fisher’s exact test along with the obtained results of variables of particle size, stability and polydispersity are statistically the same, that is, the variables do not influence statistically the formation of the particles, as well as the influence caused by H2O2 and NaBH4 variation on the AgNPs properties. In summary, variation of NaBH4 concentration and H2O2 volume causes effects under the diameter, stability and polydispersity of AgNPs which have been studied and described herein.

RESUMO Os parâmetros da cristalização a partir do fundido de um composto de fibras lignocelulósicas de côco dispersas em poli (butileno adipato tereftalato) (PBAT), uma matriz de copoliéster totalmente biodegradável, foi estudada por calorimetria exploratória diferencial (DSC). Os compostos de PBAT/fibra de côco com 10% e 20% de fibra foram preparados num misturador interno de laboratório; a reometria de torque mostrou degradação insignificante durante o processamento. A cristalização não-isotérmica a partir do fundido da matriz foi estudada por DSC em compostos com 10% de fibra com taxas de resfriamento entre 2 e 32°C/min, e informações quantitativas foram fornecidas em temperaturas e taxas de cristalização, bem como a cristalinidade desenvolvida, que apresentou valor maior do que o esperado nas altas taxas de resfriamento. Os resultados cinéticos da cristalização foram correlacionados usando modelos clássicos macrocinéticos: Pseudo-Avrami, Ozawa e Mo, para obter expressões analíticas quantitativas apropriadas para o processamento. Os modelos Pseudo-Avrami e Mo representaram bem os dados experimentais. Uma análise detalhada da modelagem é apresentada, a fim de avaliar as incertezas esperadas. Apesar de desvios observados no início e no final do processo de cristalização, o modelo Mo é recomendado como a melhor correlação empírica geral dos dados experimentais para o propósito pretendido.

ABSTRACT The melt crystallization characteristics of a compound of coconut lignocellulosic fibers dispersed in poly(butylene adipate terephthalate) (PBAT), a fully biodegradable copolyester matrix, was studied by differential scanning calorimetry (DSC). PBAT/coconut fiber compounds with 10% and 20% filler content were prepared in a laboratory internal mixer; torque rheometry showed negligible degradation during processing. Nonisothermal melt crystallization of the matrix was thoroughly studied by DSC in 10% compounds at cooling rates between 2 and 32°C/min, and quantitative information was provided on crystallization temperatures and rates, as well as the crystallinity developed, which turned out to be higher than expected at the high cooling rates. Crystallization kinetic results were correlated using classical macrokinetic Pseudo-Avrami, Ozawa, and Mo models, in order to obtain quantitative analytical expressions appropriate for processing applications. Pseudo-Avrami and Mo models were found to represent well the experimental data. A detailed analysis of the model fitting is presented, in order to assess the expected uncertainties. Despite its failings at the onset and end of the crystallization process, Mo model is recommended as best overall empirical correlation of the experimental data for the intended purpose.

Biodegradable Poly (ɛ-caprolactone) (PCL) was compounded with Brasgel PA (MMT) and Cloisite Na (CLNa), and compatibilized with maleic anhydride grafted poly(ɛ-caprolactone) (PCL-g-MA). No evidence of degradation was verified during processing, as well as particle aggregates were absent as displayed through scanning electron microscopy (SEM) images. Compatibilized compounds upon clay addition achieved higher thermal stability as visualized by thermogravimetry (TG). Montmorillonite clays acted as nucleant agent during PCL melt crystallization as evidenced by differential scanning calorimetry (DSC). Mechanical behavior of PCL was preserved, and all compounds presented Elongation higher than 350% meanwhile the heat distortion temperature (HDT) was increased by 20% in PCL compounds, which may have wider range of application and better performance.

Abstract In this work, blends based on environmentally friend polymers such as Biopolyethylene (Bio-PE), Polycaprolactone (PCL) and Polyethylene graft maleic anhydride (PEgMA) added as compatibilizer agent were produced by conventional extrusion, aiming to produce bio-blends with synergic properties at low processing cost, being at same time non-polluting and therefore contributing to the environment preservation. Differential scanning calorimetry (DSC) showed that blending does not significantly interfere on the melting and crystallization behaviors of neat polymers, suggesting being low miscibility compounds. Mechanical properties were observed changing with blend composition as the impact strength significantly increased reaching values higher than 130% when compared to neat Bio-PE. Scanning electron microscopy (SEM) images showed honeycomb morphology in Bio-PE/PCL blends, and the addition of PEgMA decreased the coalescence contributing to obtain more stable and synergic compounds. Bio-PE/PCL/PEgMA at 80/20/10 contents presented the best properties and may be used for packaging materials (food containers, film wrapping), and hygiene products.

Abstract Compounds of poly(3-hydroxybutyrate) (PHB) and titanium dioxide (TiO2) with filler content between 1% and 10% were prepared in a laboratory internal mixer. The effect of heating and cooling rates on the crystallization and melting of PHB/TiO2 compounds was investigated by differential scanning calorimetry (DSC). Melt and cold crystallization rates rise with increasing cooling/heating rates. A higher cooling rate translates to a lower melt crystallization temperature, while a higher heating rate results in a higher cold crystallization temperature. TiO2 promotes melt crystallization of PHB, behaving as a nucleant agent. The total crystallinity developed after melt and cold crystallization decreases for low levels of TiO2, i.e. 2% per weight, and is almost independent of the heating/cooling rate. The melting temperatures and rates are minimally affected by both the heating rate and filler content. The results suggest that the desired PHB microstructure can be controlled by filler content and adjusted heating/cooling rate.

The effect of alcaline and hot water surface treatments of piassava Attalea funifera fibers was investigated. The efficiency of each treatment was evaluated by Fourier transform infrared spectroscopy, X-ray diffractometry, optical microscopy, scanning electron microscopy and atomic force microscopy. The alkaline treatments were effective in removing the superficial lignin layer from the fiber, while the hot water treatment was not. Treatment with hot water and NaOH caused fiber defibrillation. NaOH was most effective in promoting both, a decrease in fiber diameter and an increase in fiber surface area. Treatment with Ca(OH)2 led to the formation of a CaCO3 layer deposited on the fiber, preventing defibrillation. The crystalline structure of the fiber was not altered by any of the treatments, maintaining type I cellulose.

ABSTRACT Films of Poly(?-caprolactone) (PCL) and PCL/Zinc Oxide (ZnO) were obtained by solution processing. Thermal behaviour and morphological structure were analysed by means of Thermogravimetry (TGA), Differential Scanning Calorimetry (DSC), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The addition of ZnO to PCL decreased the degradation temperature about 50-70°C; the films are thermally stable up to 200°C, making them suitable for packaging hot grilled chicken. ZnO did not promote significant alterations of the PCL fusion and melt crystallization, however the crystallinity increased; probably ZnO acts as nucleating agent during PCL crystallization as OM images showed greater amount of small spherulites on PCL/ZnO films. According to SEM, the methodology utilized is adequate for producing films in concentrations up to 5% ZnO.

RESUMO A Poli(ɛ-caprolactona) (PCL) é um termoplástico sintético biodegradável que tem sido foco de estudos em novos “polímeros verdes”, devido principalmente as suas boas propriedades mecânicas, o que a torna competitiva com outros polímeros convencionais e biopolímeros, tais como: Poli(ácido lático) (PLA), Poli(hidroxibutirato) (PHB). O objetivo deste trabalho foi a enxertia de grupos reativos anidrido maleico (MA) na PCL para a produção de um polímero funcional biodegradável. A síntese de enxertia do anidrido maleico na PCL ocorreu em um misturador interno de laboratório, utilizando concentrações de 2,5 e 5 % de MA e de 0,3 e 0,5% do iniciador peróxido de dicumila (DCP) em duas temperaturas de processo, 110oC e 160oC. A metodologia do planejamento fatorial 23 foi usada visando à otimização dos experimentos, assim como também para avaliar a eficiência das condições reacionais empregadas para a funcionalização da PCL. Os resultados indicaram que o anidrido maléico foi enxertado na PCL usando o iniciador peróxido de dicumila. A porcentagem de anidrido maléico grafitizado (%gMA) foi obtida por titulação e comprovada por Espectroscopia na região do Infravermelho por Transformada de Fourier (FTIR). Através dos resultados obtidos pode-se inferir que um maior teor (5,0%) de MA favoreceu positivamente a enxertia. No entanto, acima de determinada quantidade, possivelmente ocorre uma saturação do sistema e a tendência é a recombinação.

ABSTRACT Poly (ɛ-caprolactone) (PCL) is a biodegradable synthetic thermoplastic that has been the focus of studies on new "green polymers", due mainly to its good mechanical properties, which makes it competitive among other conventional polymers and biopolymers, such as, Poly(lactic acid) (PLA) and Poly(hydroxybutyrene) (PHB). The objective of this work was the grafting of maleic anhydride (MA) reactive groups in PCL for the production of a functional biodegradable polymer. The grafting synthesis of the maleic anhydride in the PCL occurred in an internal lab mixer, using concentrations of 2.5 and 5.0% MA and 0.3 and 0.5% of the dicumyl peroxide initiator (DCP) at two temperatures of process, 110°C and 160°C. The methodology of factorial planning 23 was used to optimize the experiments, as well as to evaluate the efficiency of the reaction conditions employed for PCL functionalization. The results indicated that maleic anhydride was grafted onto PCL using the dicumyl peroxide initiator. The percentage of graphitized maleic anhydride (% gMA) was obtained by titration and confirmed by Fourier Transform Infra-Red (FTIR). Through the obtained results it can be inferred that higher content (5.0%) of MA positively favored the grafting. However, over certain amount, a saturation of the system may occur and the tendency is for recombination.

Photodegradation of PCL was performed exposing injected specimens to ultraviolet radiation (UV-B) up to 9 weeks. Photodegradated PCL specimens were tested by Differential Scanning Calorimetry (DSC), Infrared Spectroscopy (FTIR), mechanical properties, Optical Microscopy (MO) and Scanning Electron Microscopy (SEM).Upon exposure decrease in elongation at break and increase of elastic modulus were verified, higher degree of crystallinity was observed for longer exposure what can be due to the chemi-crystallization mechanism. From IR spectra new carbonyl group (C=O) peaks were observed. Presence of micro cracks on specimens’ surface was identified by MO. From morphological analyses is suggested that the photodegradation in PCL takes place by bulk erosion mechanism.

Biodegradable compounds of poly(ε-caprolactone) (PCL)/ cotton linter were melting mixed with filling content ranging from 1% to 5% w/w. Cotton linter is an important byproduct of textile industry; in this work it was used in raw state and after acid hydrolysis. According to the results of torque rheometry no decaying of viscosity took place during compounding, evidencing absence of breaking down in molecular weight. The thermal stability increased by 20% as observed in HDT for PCL/cotton nanolinter compounds. Adding cotton linter to PCL didn't change its crystalline character as showed by XRD; however an increase in degree of crystallinity was observed by means of DSC. From mechanical tests in tension was observed an increase in ductility of PCL, and from mechanical tests in flexion an increase in elastic modulus upon addition of cotton linter, whereas impact strength presented lower values for PCL/cotton linter and PCL/cotton nanolinter compounds. SEM images showed that PCL presents plastic fracture and cotton linter has an interlacing fibril structure with high L/D ratio, which are in agreement with matrix/fibril morphology observed for PCL/cotton linter compounds. PCL/cotton linter compounds made in this work cost less than neat PCL matrix and presented improved properties making feasible its commercial use.