Marina Patricia Arrieta

Bionanocomposite films based on plasticized PLA-PHB/cellulose nanocrystal blends.

Optically transparent plasticized poly(lactic acid) (PLA) based bionanocomposite films intended for food packaging were prepared by melt blending. Materials were plasticized with 15wt% of acetyl(tributyl citrate) (ATBC) to improve the material processability and to obtain flexibile films. Poly(hydroxybutyrate) (PHB) was used to increase PLA crystallinity. The thermal stability of the PLA-PHB blends was improved by the addition of 5 wt% of cellulose nanocrystals (CNC) or modified cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose. The combination of ATBC and cellulose nanocrystals, mainly the better dispersed CNCs, improved the interaction between PLA and PHB. Thus, an improvement on the oxygen barrier and stretchability was achieved in PLA-PHB-CNCs-ATBC which also displayed somewhat UV light blocking effect. All bionanocomposite films presented appropriate disintegration in compost suggesting their possible applications as biodegradable packaging materials.

Multifunctional PLA-PHB/cellulose nanocrystal films: Processing, structural and thermal properties

Cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose by acid hydrolysis were added into poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends to improve the final properties of the multifunctional systems. CNC were also modified with a surfactant (CNCs) to increase the interfacial adhesion in the systems maintaining the thermal stability. Firstly, masterbatch pellets were obtained for each formulation to improve the dispersion of the cellulose structures in the PLA-PHB and then nanocomposite films were processed. The thermal stability as well as the morphological and structural properties of nanocomposites was investigated. While PHB increased the PLA crystallinity due to its nucleation effect, well dispersed CNC and CNCs not only increased the crystallinity but also improved the processability, the thermal stability and the interaction between both polymers especially in the case of the modified CNCs based PLA-PHB formulation. Likewise, CNCs were better dispersed in PLA-CNCs and PLA-PHB-CNCs, than CNC.

Combined Effect of Poly(hydroxybutyrate) and Plasticizers on Polylactic acid Properties for Film Intended for Food Packaging

Poly(lactic acid) PLA, and poly(hydroxybutyrate) PHB, blends were processed as films and characterized for their use in food packaging. PLA was blended with PHB to enhance the crystallinity. Therefore, PHB addition strongly increased oxygen barrier while decreased the wettability. Two different environmentally-friendly plasticizers, poly(ethylene glycol) (PEG) and acetyl(tributyl citrate) (ATBC), were added to these blends to increase their processing performance, while improving their ductile properties. ATBC showed higher plasticizer efficiency than PEG directly related to the similarity solubility parameters between ATBC and both biopolymers. Moreover, ATBC was more efficiently retained to the polymer matrix during processing than PEG. PLA–PHB–ATBC blends were homogeneous and transparent blends that showed promising performance for the preparation of films by a ready industrial process technology for food packaging applications, showing slightly amber color, improved elongation at break, enhanced oxygen barrier and decreased wettability.

Free amino acids and biogenic amines in Alicante Monastrell wines

The simultaneous determination of 17 free amino acids and 8 biogenic amines in Alicante Monastrell wines was investigated for the first time. The quantification was carried out by using a RP-HPLC method, based on a pre-column derivatization with o-phthaldialdehyde (OPA) and fluorescence detection. From the results obtained it may be concluded that the most abundant free amino acids were Glu, Arg, Ala Asp, and Lys. None of the wine samples analysed had histamine (HIM) or Tyramine (TYM) levels above the limits considered as a possible toxic risk for healthy individuals. No measurable amounts of cadaverine (CAD) or methylamine (MEA) were found, showing no spoilage symptoms of sensory properties of the wines. Tryptamine (TRM) content was significantly higher in aged wines compared to young wines. However ethanolamine (ETA) content was lower. These data were used to make a preliminary classification of the samples using cluster analysis.

On the Use of PLA-PHB Blends for Sustainable Food Packaging Applications

Poly(lactic acid) (PLA) is the most used biopolymer for food packaging applications. Several strategies have been made to improve PLA properties for extending its applications in the packaging field. Melt blending approaches are gaining considerable interest since they are easy, cost-effective and readily available processing technologies at the industrial level. With a similar melting temperature and high crystallinity, poly(hydroxybutyrate) (PHB) represents a good candidate to blend with PLA. The ability of PHB to act as a nucleating agent for PLA improves its mechanical resistance and barrier performance. With the dual objective to improve PLAPHB processing performance and to obtain stretchable materials, plasticizers are frequently added. Current trends to enhance PLA-PHB miscibility are focused on the development of composite and nanocomposites. PLA-PHB blends are also interesting for the controlled release of active compounds in the development of active packaging systems. This review explains the most relevant processing aspects of PLA-PHB based blends such as the influence of polymers molecular weight, the PLA-PHB composition as well as the thermal stability. It also summarizes the recent developments in PLA-PHB formulations with an emphasis on their performance with interest in the sustainable food packaging field. PLA-PHB blends shows highly promising perspectives for the replacement of traditional petrochemical based polymers currently used for food packaging.

Microstructure, mechanical, and thermogravimetric characterization of cellulosic by-products obtained from biomass seeds.

The microstructural, thermal, and nanomechanical characterization of biomass by-products coming from the food industry were studied. Scanning electron microscopy showed a microstructure formed by polygonal grains. The thermal behavior of seeds, evaluated by thermogravimetric analysis, revealed three main components (hemicellulose, cellulose, and lignin). Walnut shell showed the highest thermal stability and also the highest amount of lignin. The nanomechanical aspects were evaluated by nanoindentation. Samples with higher amount of cellulose presented minor modulus values. In accordance with the thermal stability, the highest modulus and hardness were observed in walnut. These by-products could be useful as reinforcement materials for biodegradable plastic industry.

Humidity-activated shape memory effect on plasticized starch-based biomaterials

Humidity-activated shape memory behavior of plasticized starch-based films reinforced with the innovative combination of starch nanocrystals (SNCs) and catechin as antioxidant were studied. In a previous work, we reported the processing of gelatinized starch-based films filled with SNCs and catechin as antioxidant agent, and we observed that this novel combination leads to starch-based film with enhanced thermal and mechanical performance. In this work, the humidity-activated shape memory behavior of the previous developed starch-based films was characterized. The moisture loss as well as the moisture absorption were studied since they are essential parameters in humidity-activated shape memory polymers to fix the temporary shape and to recover the original shape, respectively. Therefore, the effect of the incorporation of SNCs and catechin on the humidity-activated shape memory properties of plasticized starch was also studied. Moreover, the effectiveness of catechin to increase the polymer stability under oxidative atmosphere and the thermo-mechanical relaxation of all the starch-based materials were studied. The combination of plasticized starch matrix loaded with both, SNCs and catechin, leads to a multifunctional starch-based films with increased hydrophilicity and with excellent humidity-activated shape memory behavior with interest for potential biomedical applications.

PIRÓLISIS DE RESIDUOS DE BIOPLÁSTICOS: PRODUCTOS OBTENIDOS DEL ÁCIDO POLILÁCTICO ( PLA)

ABSTRACT Pyrolysis of bioplastics waste may offer an alternative waste treatment option, allowing the recovery of resources. Bioplastics have taken special interest in the industry. They could be an alternative to conventional petroleum based plastics. Polylactic acid (PLA) is a bioplastic that has gained big interest during the last two decades. Pyrolysis of bioplastics waste may be economically and environmentally attractive. In order to obtain optimal energy recovery with an appropriate composition of emitted products, pyrolysis treatment has to ensure the adequate conditions. In this work, the thermal degradation of PLA was studied by pyrolysis coupled with gas chromatography and mass spectrometry detection. The test conditions allowed to identify and quantify the major compounds produced during thermal degradation of PLA.

PLA-Based Nanocomposites Reinforced with CNC for Food Packaging Applications: From Synthesis to Biodegradation

Poly(lactic acid) (PLA) is currently the most used biopolymer in several food packaging applications at industrial level, due to its many advantages such as high transparency, availability in the market, and ease of processing. However, PLA presents some drawbacks such as its poor mechanical, thermal, and barrier properties. The addition of nanofillers to PLA matrix leads to an enhancement in the thermomechanical performance. The optimal nanofiller should be nontoxic, approved for food contact, renewable, and biodegradable. Cellulose derivatives, particularly cellulose nanocrystals (CNCs), are optimal fillers with interesting properties (i.e., stiff, lightweight, highly abundant in nature, at low cost, and biodegradable). In this chapter the current industrial PLA obtainment, processing, and compostability are reviewed in relation to its application as sustainable food packaging material. The advantages of reinforcing PLA with CNC to improve the thermal, mechanical, and barrier performance of the final bionanocomposites are also summarized.

6 – Smart Polymers

Polymer materials, in their early days, were mostly studied for use as static structural parts. However, in the last decades, advanced multifunctional polymers able to interact with the external conditions have attracted more and more attention. At the same time, in recent years, the increase in life expectancy has led to a growing demand for both new materials and new technologies. Moreover, due to the outstanding properties of natural materials, scientists try to imitate and to follow the principles that nature has developed over millions of years in order to design new bio-inspired materials. To this regard, one of the most inspiring properties is the capability of the material to change specific properties upon the application of an external stimulus, obtaining shape memory materials. In this chapter the attention will be focused on different shape memory polymeric materials, in particular on the stimuli-responsive materials in smart packaging, on the principles of shape memory polymer-based materials, on self-healing polymers, and on hydrogels.