Effect of the radiolitic sterilization in polyethylene/starch blends

Samples of LDPE/modified starch blends 80/20 m/m before and after exposure to gamma rays were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The effect of gamma radiation is clearly seen in the samples irradiated at a dose of 25 kGy. The main alteration in the polymeric material after exposure at the radiation range was a decrease in the mechanical properties, alterations in the chemical structure of the blend with an increase in the carbonyl and vinyl indices and the appearance of new crystalline symmetry generating a crystalline domain not existing before in the blend

O efeito da adição da inulina na produção do queijo coalho: avaliação da caracterização

The present work proposed to analyze a coalho cheese with inulin. For that, inulin was added, in the stirring stage, during the process of making the coalho cheese to obtain two samples: SCC (standard coalho cheese) and ICC (coalho cheese with inulin). In the two studied samples, the following analyzes were carried out: pH, acidity, water activity and colorimetric. As well as it was possible to know the effect of the addition of inulin when stored under refrigeration for 14 days from the analysis of instrumental texture profile, melting capacity, acceptability test and purchase intention. The studied coalho cheese samples showed differences in physical-chemical and instrumental parameters evaluated. Inulin contributed to obtaining cheeses with less melting capacity and with a firm, soft texture and little adhesiveness. Both cheeses showed high luminosity (L*) and predominance of yellow color (b*) in detriment of green (a*). The various sensory attributes evaluated by tasters, as well as purchase intention, indicated good results for this new product. The proposed work contributes to the development of a profitable market for new dairy products enriched with physiologically active components, prebiotics, which is currently one of the research priorities of the food industry

Caracterização térmica de filmes ativos biodegradáveis de PBAT aditivados com óleo de laranja / Thermal characterization of biodegradable active films of PBAT additivated with orange oil

The development of new packaging for food preservation has been improving every day. The use of antimicrobial agents extracted from plants offers greater security to the packages because they are obtained by natural means. The use of orange oil as an antimicrobial agent in biodegradable films is an important means of combining antimicrobial action and biodegradability. Thus, this work aims to evaluate the thermal properties in active films produced from PBAT and orange essential oil. The thermal properties were evaluated by differential exploratory calorimetry (DSC) and thermogravimetric analysis (TGA). The presence of the oil was confirmed by Principal Component Analysis (PCA). The thermal stability of the PBAT was not altered with the addition of the oil, as there was no change in the melt temperature (Tm), thus increasing the crystallization temperature (Tc). Therefore, the use of PBAT with orange oil may be a promising source for use as an active packaging, in addition to not altering the thermal stability of the polymer, improving the processability of the material by increasing its crystallization temperature. 

Crystallization kinetics of poly (butylene adipate terephthalate) in biocomposite with coconut fiber

Os parâmetros da cristalização a partir do fundido de um composto de fibras lignocelulósicas de côco dispersasem poli (butileno adipato tereftalato) (PBAT), uma matriz de copoliéster totalmente biodegradável, foiestudada por calorimetria exploratória diferencial (DSC). Os compostos de PBAT/fibra de côco com 10% e20% de fibra foram preparados num misturador interno de laboratório; a reometria de torque mostrou degradaçãoinsignificante durante o processamento. A cristalização não-isotérmica a partir do fundido da matrizfoi estudada por DSC em compostos com 10% de fibra com taxas de resfriamento entre 2 e 32°C/min, e informaçõesquantitativas foram fornecidas em temperaturas e taxas de cristalização, bem como a cristalinidadedesenvolvida, que apresentou valor maior do que o esperado nas altas taxas de resfriamento. Os resultadoscinéticos da cristalização foram correlacionados usando modelos clássicos macrocinéticos: Pseudo-Avrami,Ozawa e Mo, para obter expressões analíticas quantitativas apropriadas para o processamento. Os modelosPseudo-Avrami e Mo representaram bem os dados experimentais. Uma análise detalhada da modelagem éapresentada, a fim de avaliar as incertezas esperadas. Apesar de desvios observados no início e no final doprocesso de cristalização, o modelo Mo é recomendado como a melhor correlação empírica geral dos dadosexperimentais para o propósito pretendido.Palavras-chave: PBAT, fibra vegetal, cristalização a partir do fundido, modelos cinéticos

Degradation studies on plasticized PVC films submited to gamma radiation

Poly (vinyl chloride), PVC, is a rigid polymer and for several of its applications must be compounded with plasticizing agents. The plasticizers minimize the dipolar interactions, which exist between the polymer's chains, promoting their mobility. In this work we studied the properties of PVC/plasticizer systems submitted to different doses of gamma radiation. We have used four commercial plasticizers amongt them di(2-ethylhexyl) phthalate, DEHP, which is present in a great number of commercial applications. The PVC/plasticizer systems have been studied as films made by the solvent evaporation technique. Irradiated and non-irradiated films have been characterized by viscosimetric analysis, mechanical essays and infrared spectroscopy. The results have shown that the rigid, non plasticized, PVC film presented the greatest degradation index, while among the plasticized films the one which presented the larger degradation index due to chain scission was the DEHP plasticized PVC

Effect of organoclay and corn straw on the properties of poly (butylene adipate-co-terephthalate) (PBAT) hybrid composites

The packaging industry requires permeable materials capable of offering freshness of the packaging content. The use of fillers can enhance these permeable properties to the polymeric material. This work investigates the effect of incorporating different fillers (organophilic clay and corn straw) on the rheological, mechanical, permeability, water absorption and biodegradability characteristics of poly (butylene adipate co-terephthalate) (PBAT) processed in an internal laboratory mixer. Extruded films and specimens injection molded were produced. The results of torque rheometry suggest polymer matrix degradation during processing slightly increase, also evidenced by MFR results. Composite films showed a drop in tensile strength, higher stiffness and lower elongation. Incorporation of the fillers in the PBAT matrix enhanced the permeability to oxygen gas of the produced films. The presence of fillers significantly increased the capacity of water absorption. The incorporation of C20A and, mainly, CS tends to accelerate the biodegradation of PBAT. Adding small amounts of organoclay C20A and CS to PBAT leads to a material that combines maintenance or improvement of biodegradation combined with higher permeability to oxygen, which indicates the potential use of these systems in packaging industry for maintenance of freshness of content.The packaging industry requires permeable materials capable of offering freshness of the packaging content. The use of fillers can enhance these permeable properties to the polymeric material. This work investigates the effect of incorporating different fillers (organophilic clay and corn straw) on the rheological, mechanical, permeability, water absorption and biodegradability characteristics of poly (butylene adipate co-terephthalate) (PBAT) processed in an internal laboratory mixer. Extruded films and specimens injection molded were produced. The results of torque rheometry suggest polymer matrix degradation during processing slightly increase, also evidenced by MFR results. Composite films showed a drop in tensile strength, higher stiffness and lower elongation. Incorporation of the fillers in the PBAT matrix enhanced the permeability to oxygen gas of the produced films. The presence of fillers significantly increased the capacity of water absorption. The incorporation of C20A and, mainly, CS tends to accelerate the biodegradation of PBAT. Adding small amounts of organoclay C20A and CS to PBAT leads to a material that combines maintenance or improvement of biodegradation combined with higher permeability to oxygen, which indicates the potential use of these systems in packaging industry for maintenance of freshness of content

Influence of a Multifunctional Epoxy Additive on the Performance of Polyamide 6 and PET Post-Consumed Blends during Processing

In this study, a commercial chain extender (Polyad PR 002) in concentrations of 0.5, 1.0, and 1.5% w/w was used as a compatibilizer in post-consumed PET/PA6 blends (25/75, 50/50 e 75/25) processed in a laboratory mixer. The degradation rate, phase miscibility, chemical interaction, crystallization, and melting behavior, as well as the thermal stability of the mixtures, were analyzed by torque rheometry, scanning electron microscopy (SEM), FTIR spectroscopy, differential scanning calorimetry (DSC), and thermogravimetry (TGA), respectively. The results showed that the addition of 1% chain extender was sufficient to increase the melt viscosity of the PET-rich mixtures and 1.5% for the PA6-rich samples. Clearly, adding Polyad PR 002 to PET/PA6 blends improves polymer compatibility; for the 25%PET/75%PA6 blend with 1.5% PR 002, complete miscibility was observed, indicating a new compatible blend formation, revealing a chemical reaction between the systems, and proving the synergism between them. This chain extender did not affect the thermal stability of the blends, and the low contents employed reduced the crystallization rate of the blends investigated