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

Nanocellulose in green food packaging

The development of packaging materials with new functionalities and lower environmental impact is now an urgent need of our society. On one hand, the shelf-life extension of packaged products can be an answer to the exponential increase of worldwide demand for food. On the other hand, uncertainty of crude oil prices and reserves has imposed the necessity to find raw materials to replace oil-derived polymers. Additionally, consumers' awareness toward environmental issues increasingly pushes industries to look with renewed interest to "green" solutions. In response to these issues, numerous polymers have been exploited to develop biodegradable food packaging materials. Although the use of biopolymers has been limited due to their poor mechanical and barrier properties, these can be enhanced by adding reinforcing nanosized components to form nanocomposites. Cellulose is probably the most used and well-known renewable and sustainable raw material. The mechanical properties, reinforcing capabilities, abundance, low density, and biodegradability of nanosized cellulose make it an ideal candidate for polymer nanocomposites processing. Here we review the potential applications of cellulose based nanocomposites in food packaging materials, highlighting the several types of biopolymers with nanocellulose fillers that have been used to form bio-nanocomposite materials. The trends in nanocellulose packaging applications are also addressed.

Preparation and crystallization behavior of poly(ethylene 2,5-furandicarboxylate)/cellulose composites by twin screw extrusion

Poly(ethylene 2,5-furandicarboxylate) (PEF), an emerging biobased polyester, was compounded with cellulose via twin-screw extrusion. Different extrusion parameters such as mixing time, screw speed and temperature were employed. Composite thin films containing 1, 2 and 4% cellulose w/w were prepared and compared with neat PEF films. The morphology of PEF/cellulose composites was examined by scanning electron microscopy (SEM) and the molecular weight after extrusion was controlled by means of size exclusion chromatography (SEC). The influence of the cellulose on both isothermal and non-isothermal crystallizations of PEF was investigated by differential scanning calorimetry (DSC). Crystallization is faster in presence of cellulose and the nucleating effect increases with the cellulose concentration.

Production of nanocellulose in miniature-bioreactor: Optimization and characterization

Bacterial cellulose (BC) is a very fascinating microbial biopolymer which is mainly produced by Gluconacetobacter xylinum. Optimization of BC production by G. xylinum was performed based on scale-down studies in miniature-bioreactor and response surface methodology in which the optimum pH value (6.5) and shaking rate (50 rpm) were obtained. The static culture condition for BC production has newly been defined. Nanostructure of BC includes nanofibers up to (60 nm) and nanoporosity up to (265 nm) was observed by scanning electron microscopy. By Fourier transform infrared spectroscopy study, the most expected BC interaction is nucleophilic interaction. MTT assay showed high biocompatibility. Appropriate mechanical strength (0.37 MPa) and Young's modulus (3.36 MPa) evinced BC scaffold utilization for skin tissue. The results indicate that BC sheets can be utilized in biomedical application and nanotechnology approaches.

Poly(lactic acid) melt-spun fibers reinforced with functionalized cellulose nanocrystals

Poly(lactic acid)-cellulose nanocrystals (PLA/CNC) nanocomposite fibers with 1% weight fraction of nanocrystals were prepared via melt-spinning.

Cytocompatible antibacterial fibrous membranes based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and quaternarized N-halamine polymer

A novel polymeric N-halamine-containing quaternary ammonium salt (PHQS) was synthesized and used to make antibacterial electrospun fibrous membranes by blending with biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-4HB)).

Polylactic acid nanocomposite films with spherical nanocelluloses as efficient nucleation agents: effects on crystallization, mechanical and thermal properties

An important industrial problem (low crystallization rate) for commercial polylactic acid (PLA) is addressed by incorporating SCNFs as efficient nucleation agents.

Aplicação de nanotecnologia em embalagens de alimentos

Resumo A nanotecnologia tem grande potencial de aplicação na indústria de alimentos. No desenvolvimento de embalagens, pode proporcionar diferentes alternativas, tais como o desenvolvimento de nanopartículas, nanodispersões, nanolaminados, e nanotubos, que, associados aos polímeros, podem fornecer diversas funções. Por exemplo, pela incorporação de nanopartículas com propriedades antimicrobianas; nanosensores capazes de detectar produtos químicos, agentes patogênicos e toxinas em alimentos; nanopartículas bioativas capazes de manter os compostos em condições ideais, até a sua migração para o produto alimentício e nanocompósitos, que melhorem as propriedades de flexibilidade, barreira a gases e umidade e quanto à absorção de irradiação UV dos materiais aos quais são incorporados, assim como a estabilidade frente à temperatura. Este artigo relata algumas aplicações da nanotecnologia em embalagens de alimentos, bem como questões sobre toxicidade e regulamentação relacionadas à possibilidade de migração das nanopartículas para os alimentos; razão pela qual o setor alimentício tem sido cauteloso com a utilização desses materiais.

Melt free radical grafting of glycidyl methacrylate (GMA) onto fully biodegradable poly(lactic) acid films: effect of cellulose nanocrystals and a masterbatch process

This article reports the preparation, by means of a masterbatch procedure, of poly (lactic acid) (PLA)/cellulose nanocrystal (CNC) films via premixing 1% wt of CNC into PLA or glycidyl methacrylate (GMA) grafted PLA (g-PLA).

Plasticized poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends incorporated with catechin intended for active food-packaging applications

Active biobased packaging materials based on poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends were prepared by melt blending and fully characterized. Catechin incorporation, as antioxidant compound, enhanced the thermal stability, whereas its release was improved by the addition of acetyl(tributyl citrate) (ATBC) as plasticizer. Whereas the incorporation of ATBC resulted in a reduction of elastic modulus and hardness, catechin addition produced more rigid materials due to hydrogen-bonding interactions between catechin hydroxyl groups and carbonyl groups of PLA and PHB. The quantification of catechin released into a fatty food simulant and the antioxidant effectiveness after the release process were demonstrated. The effect of the materials' exposure to a food simulant was also investigated. PHB-added materials maintained their structural and mechanical properties after 10 days in a test medium that represents the worst foreseeable conditions of the intended use. Thus, plasticized PLA-PHB blends with catechin show their potential as biobased active packaging for fatty food.