Lucia Helena Innocentini Mei

PLA and Montmorilonite Nanocomposites: Properties, Biodegradation and Potential Toxicity

The concern related to solid waste increases efforts to develop products based on biodegradable materials. At present, PLA has one of the highest potentials among biopolyesters, particularly for packaging. However, its application is limited in some fields. In order to optimize PLA properties, organo-modified montmorilonites have been extensively used to obtain nanocomposites. Although PLA nanocomposites studies are widely reported in the literature, there is still few information about the influence of organoclays on de biodegradation process, which is a relevant information, since one of the main purposals related to the final disposal of biopolymers as PLA is composting. Besides, in the last years some research has been conducted in order to evaluate the potential toxicity of montmorilonite, unmodified or organo-modified. Since the use of montmorilonite is expanding in different applications, human exposure and risk assessment are important issues to be investigated. In this context, this review intends to compile available information related to common organoclays used for PLA nanocomposites, its properties, biodegradation analysis and potential toxicity evaluation of nanocomposites, focused on montmorilonite as filler. Two issues of relevance were pointed out. The first is food safety and quality, and the second consideration is the environmental effect.

Properties that characterize the propagation of cracks of recycled glass fiber reinforced polyamide 6

Industrial wastes of glass fiber reinforced polyamide 6 originating from injection molding were reprocessed and characterized by measurements of relative viscosity, impact strength, fiber average length and fiber length distribution. The results show that the set of characterization techniques used are efficient to reproduce the behavior of reprocessed polymeric composites and to compare them with the virgin material.

Study of PBAT Photostabilization with Ultraviolet Absorber in Combination with Hindered Amine Light Stabilizer and Vitamin E, Aiming Mulching Film Application

This work evaluated two combinations of additives, i.e. “carbon black and hindered amine light stabilizer (HALS)” and “carbon black and vitamin E” to prevent photodegradation of poly(butylene adipate-co-terephthalate) (PBAT) aiming its application as mulch films. A 22 factorial rotatable central composite design (α = 1.414) with three central points was conducted. Five different concentrations for each additive were used (0.1, 0.5, 1.0, 1.5 and 2.0% in mass). The formulations were exposed in an environmental simulator to radiation and condensation cycles. The both combination did not avoid the gel formation but its action reduced PBAT chain scission process during photodegradation. Nevertheless, comparing the two different combinations with carbon black, HALS additive was more efficient than vitamin E to minimize the reduction on tensile strength and elongation. The chain scission and crosslinking processes were evaluated by chain scission distribution function. The chain scission was the predominant process during photodegradation of pure PBAT and it was possibly favored by hydrolysis during condensation cycles in the accelerated aging test. It was verified that higher concentrations of carbon black in the formulations led to a reduction on light transmission in both experimental designs. Considering the responses of studied factors on mechanical properties and light transmission it was possible to identify the most promising formulations for application in mulch films, which correspond to 1.5% (weight) for each additive.

Development of Multilayer Films Obtained From Epoxidized Methyl Esters, Polyhydroxyalkanoates and Their Combinations

The aim of this work was the production and characterization of films prepared from starch, gelatin and methyl esters of epoxidized macauba (Acrocomia aculeata), corn (Zea mays), pacu (Piaractus mesopotamicus), pintado (Pseudoplatystoma corruscans) and soybean (Glycine max) and also multilayer films of polyhydroxyalkanoates (PHA) conjugated with two of the epoxides that presented the best results in characterizations. The two types of films EEF (Epoxidized esters films) and EEFPHA (Epoxidized esters and PHA conjugated films) were both characterized for their visual aspects, solubility in water and acid, width, color, opacity, water vapor permeability, tensile strength and elongation. EEFPHA were also characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction analyses. The epoxidation reaction was successfully carried out; with the GC-MS analysis indicating the formation of epoxidized esters derived from linoleic and oleic acids. The addition of the epoxidized esters to the EEF films caused an increase in film thickness, opacity, solubility in water, tensile strength and elongation, while the solubility in acid presented the same value as compared to the blank sample. In the EEFPHA samples, addition of filmogenic solution of epoxidized esters from corn and macauba presented a value exceeding the standard in the thickness, opacity, water solubility, water vapor permeability and tensile strength analyses. In the analysis of solubility in acid these samples showed results below the standard, and the elongation test showed values very close. DSC, SEM and XRD results showed that there was a polymeric incorporation between the starch and the PHA.