PCL/ZnO Bio-friendly Films as Food Packaging Material.Thermal and morphological analysis

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), DifferentialScanning 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 thermallystable up to 200°C, making them suitable for packaging hot grilled chicken. ZnO did not promote significantalterations of the PCL fusion and melt crystallization, however the crystallinity increased; probably ZnO actsas nucleating agent during PCL crystallization as OM images showed greater amount of small spherulites onPCL/ZnO films. According to SEM, the methodology utilized is adequate for producing films in concentrationsup to 5% ZnO.Keywords: PCL, ZnO, Thermal behaviour, Morphological structure

Comparative study of the effect of TiO2 and ZnO on the crystallization of PHB

Foram preparados compósitos PHB/TiO2 e PHB/ZnO num misturador interno de laboratório, a cristalizaçãofoi investigada por calorimetria exploratória diferencial (DSC), com taxas de aquecimento e resfriamentoentre 5 e 30 °C/min e a superfície de fratura de seletas composições analisada por microscopia eletrônica devarredura (MEV). Através das imagens de MEV foi observado que as nanopartículas de ZnO e TiO2 estãobem dispersas na matriz de PHB. Por DSC, observou-se que a adição de TiO2 e ZnO modificou a temperaturae taxa de cristalização do PHB, sem afetar significativamente a cristalinidade total. Em geral, a adição dacarga TiO2 promoveu alterações mais significativas na matriz de PHB, comportando-se como um agente nucleante

Optimization of Epoxy Resin: An Investigation of Eggshell as a Synergic Filler

Epoxy resin based on bisphenol A diglycidyl ether/anhydride methyl tetrahydrophthalic/2,4,6-tris(dimethylaminomethyl)phenol (DGEBA/MTHPA/DEH 35) was produced by magnetic stirring; chicken eggshell (ES) was added as cure improver. Thermal stability, cure parameters, mechanical properties, and fracture surface were investigated by thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile experiments, and scanning electron microscopy (SEM). In general, the addition of ES slightly decreased the thermal stability, being T0.05 5% lower than that of the reference sample. The cure rate increased with the heating rates, while best results were obtained upon addition of neat membrane (M) from ES. Surprisingly, the mechanical properties were significantly improved with ES as well as with M, being the Young’s modulus 18% higher, the tensile strength 50% higher, and the deformation 35% higher than those of epoxy resin. SEM images showed that the synthetic compounds presented a smooth fracture surface, while the compounds with ES and M had a rougher surface with multiplane fractures, suggesting a fracture with higher energy absorption. In conclusion, epoxy/ES composites with better performance were produced, and effective tools are provided to control and attain in the future even better properties with ecological features

Effect of heat cycling on melting and crystallization of PHB/TiO2 compounds

<div><p>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.</p></div

Effect of Babassu on PLA Cold Crystallization

Poly(lactic acid) (PLA) based vegetal Babassu composites were compounded in this work. Babassu acted as an effective nucleating agent and improver for the whole nonisothermal cold crystallization of PLA. The nonisothermal cold crystallization of PLA compounds was investigated by Differential Scanning Calorimetry (DSC) and the activation energy was evaluated by Friedman equation. The crystallization rate of PLA increased upon increasing the heating rates as well as adding Babassu. From a Friedman analysis was shown that Babassu reduces the activation energy of the crystallization process, leading to a shorter crystallization time. As Babassu is inexpensive filler its composites costs less than neat PLA additionally being productively less time and energy consuming