ABSTRACT Starch is the most natural polymer used in the food and non-food industry. Sweet potato is among the world’s most important, versatile and underexploited food crops; its composition depends on the planting strategy, climatic conditions, cultivar, geographic region, soil quality, and other. The physical-chemical characteristic and functional properties depends also of the amylose, amylopectin ratio and the molecular components of amylose and amylopectin. In this study, the structural and physicochemical properties of starches from four sweet potato genotypes cultivated in Brazil were compared. Starch granules of roots of sweet potato all exhibited oval and irregular shapes with granule sizes ranging from 8 to 30 µm. Amylose contents of roots of sweet potato starches differed from 9.7 to 15.1%. Ratios of 1045/1022 and 1022/995 cm-1 of Fourier transform infrared spectra varied in the range of 0.8114–0.8558 and 0.9046–0.9347, respectively, which means that the genotypes present different structure ordering. Also, the digestibility, swelling power, and solubility showed some differences between the starches, probably due to the differences in amylose and amylopectin contents and granules sizes. The different genotypes showed similar thermal stability. Our study indicated the sweet potato genotypes are greatly influenced the amylose content, structure order, the degree of short-range order, granule size, digestibility, swelling power and solubility of sweet potato genotypes.

Abstract In this work, banana fiber was used as reinforcement for the preparation of a thermoplastic elastomer composite (TPE). Few studies are exploring the natural fiber incorporation on TPEs, with no one using banana fiber. The fiber was extracted from banana pseudostem and modified with an alkaline solution. The untreated and treated banana fibers were incorporated in 2%, 5%, and 10% in SEBS. The mixture was performed in a thermokinetic mixer (K-Mixer) and plates prepared by compression molding. The composites were characterized by Scanning Electron Microscopic (SEM), tensile testing, mechanical dynamical analysis (DMA). It can be observed that the samples with untreated fibers presented a higher tensile strength, except for the incorporation of 5% of BF. Young's modulus increase as the fiber's incorporation grows, indicating greater rigidity of the composite. It was found that the chemically treated banana fiber composites, e.g., TPE/TBF5 and TPE/TBF10, shows a 15.4% and 22.2% higher elongation.

RESUMO As indústrias têxteis estão entre os setores mais poluidores do mundo, principalmente pelo descarte de resíduos de corantes sintéticos nos efluentes. Alguns processos têm sido utilizados atualmente para a remoção de corantes dos efluentes, mas apresentam as desvantagens de baixa viabilidade econômica e dificuldade de reprodução em larga escala. Em paralelo, o descarte e a degradação de resíduos sólidos também constituem sérios problemas ambientais que colocam desafios às estratégias de reciclagem e degradação. O presente estudo descreve um eficiente mecanismo de remoção e degradação de corantes de efluentes com o uso de resíduos sólidos particulados. A justificativa desse processo é o uso de resíduo particulado sólido para adsorver corantes dissolvidos em água, tornando ambos os adsorventes e resíduos adsorvidos mais suscetíveis à fotodegradação. No presente estudo: uma porfirina sintética aniônica TPPS4 (meso-tetrakis (4-sulfonatofenil) porfirina) foi usada como um modelo de corante fotossensível a ser removido da água. Os modelos de resíduos sólidos foram poli (ácido láctico) (PLA) puro e misturado com 10% de amido termoplástico (TPS). As porfirinas livres e adsorvidas degradaram pela exposição de um dia à luz solar. O TPPS4 foi adsorvido de forma mais eficiente no PLA / TPS e degradado mais rapidamente no PLA. A adsorção da porfirina promoveu a fotodegradação de PLA e PLA/TPS.

ABSTRACT Textile industries are among the most pollutant sectors in the world, mainly by the discard of synthetic dye residues in effluents. Some processes currently used for the removal of dyes from the effluents have the disadvantages of low economic viability and difficulty for reproducing on a large scale. In parallel, the disposal and the degradation of solid waste also constitute serious environmental problems that pose challenges for recycling and degradation strategies. Considering that some dyes have photosensitizing properties and some discarded solid materials are porous, the present study proposes a strategy for removal and concomitant degradation of effluent dyes and particulate solid wastes. The rationale of this process is the use of solid particulate residue to adsorb dyes dissolved in water making both the adsorbed residue and adsorbents more susceptible to photodegradation. In the present study: an anionic synthetic porphyrin TPPS4 (meso-tetrakis (4-sulfonatophenyl) porphyrin) was used as a model of photosensitizing dye to be removed from the water. The solid waste models were neat poly(lactic acid) (PLA) and mixed with 10 wt% of thermoplastic acid (TPS). The free and adsorbed porphyrins degraded by one-day exposure to sunlight. TPPS4 adsorbed more efficiently in PLA/TPS and degraded faster in neat PLA. Adsorption of the porphyrin promoted photodegradation of both PLA and PLA/TPS.

ABSTRACT This work aimed to evaluate three different milling conditions, seeking the optimization of CNS isolation process. The paper sludge was chemically treated with detergent and H2O2, by two steps, to remove the noncellulosic contents (hemicellulose and lignin). After these treatments, the sample was milled with the variation of a liquid medium. The three liquids milling medium were: i) dry medium (CNS-D); ii) moist with water and (CNS-W) iii) moist with ethanol (CNS-E). The CNSs were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), zeta potential and dynamic light scattering (DLS). The milled samples presented different behavior, depending on the medium applied. The CNS-W presented low efficiency due to the formation of agglomerates around the ceramic ball, resulting in larger fiber sizes (microsizes). Although, the samples CNS-D and CNS-E presented similar behavior of sizes distribution, with average size 340 nm and 373 nm, respectively, determined by DLS. The CNS-E sample presented higher yield and electrostatic stability in solution, besides not presenting loss of crystallinity, as occurred with CNS-D, observed by FTIR analysis. Thus, the isolation with ethanol showed more efficient process among the three processes studied. This work achieved the isolation of CNS; besides, it proposed an environmentally friendly isolation method, and this may add value in the paper sludge.

ABSTRACT Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorporated to inhibit polyolefins or polyesters oxidation. However, synthetic antioxidants use is under restricted regulation due to their potential health risk and environmental impacts. Thus, great interest has been attracted to the phenol-based natural antioxidant such as lignin. This work aimed to evaluate the thermostability of kraft lignin (KL) as a natural antioxidant when incorporated into poly(butylene adipate-coterephthalate) (PBAT) matrix. PBAT-KL films (0%, 1%, 3%, 5% and 10%, by mass) were prepared by twin-screw extrusion followed by thermo-compression. These materials were examined in detail for their effect on the thermal stability using the oxidative induction time (OIT), oxidative induction temperature (OITemp) and thermogravimetric analysis (TG). According to the results, lignin-containing compositions have improved thermal resistance in oxidative environment, compared to neat PBAT. However, 10 wt.% lignin composition presented the lowest thermostability among lignin-containing compositions. The results showed that kraft lignin promotes the thermal stabilization of PBAT films at the optimal concentration of 1% by mass.

The paper industry primary waste is usually deposited in landfills or incinerated. This material has a high content of lignocellulosic components, which could be converted to cellulose nanostructures (CNS). This study aimed to compare compositional (Fourier transform infrared spectroscopy), thermal (thermogravimetric analysis), morphological (scanning electron microscopy) and dimensional (dynamic light scattering and atomic force microscopy) properties of CNS obtained through chemical and mechanical isolation processes. The FTIR results showed similar chemical bonding for both nanostructures, which indicated presence of cellulose and lignin. Their average size was 170 nm and 209 nm for chemical and mechanical processes, respectively. The morphology of SEM images showed a compact structure and the chemical isolation presents smaller CNS agglomeration than mechanical. TGA results showed higher thermal stability for CNS-chemical than CNS-mechanical samples and AFM images indicate the CNS morphologies, which showed nanoroads for CNS-chemical and nanoneedles for CNS-mechanical.

Abstract A growing global trend for maximum use of natural resources through new processes and products has enhanced studies and exploration of renewable natural materials. In this study, cardanol, a component of the cashew nut shell liquid (CNSL), was used as a building block for the development of a thermosetting matrix, which was reinforced by raw and modified sponge gourd fibers (Luffa cylindrica). DSC and TG results showed that among biocomposites, the one reinforced by sponge gourd fibers treated with NaOH 10 wt% (BF10) had the highest thermal stability, besides the best performance in the Tensile testing, showing good incorporation, dispersion, and adhesion to polymer matrix, observed by SEM. After 80 days of simulated soil experiments, it has been discovered that the presence of treated fiber allowed better biodegradability behavior to biocomposites. The biobased thermoset plastic and biocomposites showed a good potential to several applications, such as manufacturing of articles for furniture and automotive industries, especially BF10.

O acúmulo de resíduos poliméricos tem crescido nos últimos anos e os subsolos dos lixões já estão saturados com resíduos plásticos. Isso possivelmente se deve à elevada produção de resíduos sólidos de plásticos (cerca de 25 mil t/dia em 2008, segundo a Lei de Resíduos). Em vista disso, este trabalho apresenta uma análise comparativa do estudo do potencial de (bio)degradação de compostos de PVC utilizando um plastificante de origem vegetal renovável (PFR) com estrutura de éster de milho com massa molar 296,5 g.mol- 1 e dois plastificantes sintéticos, ftalato de dioctila (DOP) e adipato de dioctila (DOA), buscando inovar na obtenção de um composto de PVC com um plastificante de fonte renovável. Os resultados de FTIR evidenciaram maior interação do PFR com a resina de PVC para o teor de 30 phr, e para o teor de 40 phr observou-se que os plastificantes DOP e PFR apresentaram os mesmos valores de variação da banda atática. Já os ensaios mecânicos reforçaram os resultados de FTIR com maior compatibilidade para as composições contendo PFR. Uma maior estabilidade térmica no composto de PVC foi observada por TGA para a amostra contendo 40 phr de DOA, o que foi confirmado por RMN, e para a amostra com PFR nos teores de 30 e 40 phr. Por fim, uma perda significativa de massa foi observada nos ensaios de resistência à extração por solvente para os compostos contendo DOA, sendo que a amostra com 30 phr mostrou menor valor de extração. A biodegradação em solo simulado mostrou maior perda de massa para as amostras plastificadas com DOA (40phr) e PFR (40phr). Isso indica que é viável usar plastificante de fonte renovável nos compostos de PVC, devido à compatibilidade deste com esta resina.

The accumulation of polymeric waste in the environment has increased in recent years and landfills are already saturated with plastic waste, with an estimated production of ~25,000 t of solid plastic waste per day in Brazil, based on data for 2008. In this report, we describe a comparative analysis of the biodegradation of PVC compounds containing a renewable vegetable-derived plasticizer (RVP) with ester structure of corn and molar mass 296.5 g.mol- 1, or one of two synthetic plasticizers (dioctyl phthalate - DOP and dioctyl adipate - DOA). FTIR showed a greater interaction of RVP with the PVC resin at a content of 30 phr compared to the two synthetic plasticizers. In contrast, at 40 phr, the plasticizers DOP and RVP showed the same variation in the atactic band. Mechanical tests reinforced the results of FTIR by showing greater compatibility for compositions containing RVP. Thermogravimetric analysis showed that PVC compounds containing DOA at 40 phr were thermostable, as were compounds containing RVP at 30 and 40 phr. NMR confirmed the influence of the plasticizers on thermal stability. Compared to other combinations, samples plasticized with DOA showed significant loss of mass in tests of resistance to solvent extraction and biodegradation in simulated soil. These results demonstrate that RVP is compatible with PVC and suggest that this plasticizer could be a useful substitute for synthetic plasticizers in PVC-based products.