Dispersion of Micro Fibrillated Cellulose (MFC) in Poly(lactic acid) (PLA) from Lab-Scale to Semi-Industrial Processing Using Biobased Plasticizers as Dispersing Aids
Abstract:In the present study, two commercial typologies of microfibrillated cellulose (MFC) (Exilva and Celish) with 2% wt % were firstly melt-compounded at the laboratory scale into polylactic acid (PLA) by a microcompounder. To reach an MFC proper dispersion and avoid the well-known aglomeration problems, the use of two kinds of biobased plasticisers (poly(ethylene glycol) (PEG) and lactic acid oligomer (OLA)) were investigated. The plasticizers had the dual effect of dispersing the MFC, and at the same time, they c… Show more
“…This MFR decrement is also reflected in the injection pressure increment during the injection molding process ( Table 2 ). The marked viscosity decrement observed during the lab-scale step is limited, thanks to the coupling of the low extruder residence time and the presence of the venting system connected to a vacuum pump that guarantees the humidity stripping during the melt extrusion, avoiding or limiting any eventual PLA degradation [ 49 , 50 ]. The mechanical results are noteworthy.…”
In this work, two different typologies of hazelnuts shell powders (HSPs) having different granulometric distributions were melt-compounded into poly(lactic acid) (PLA) matrix. Different HSPs concentration (from 20 up to 40 wt.%) were investigated with the aim to obtain final biocomposites with a high filler quantity, acceptable mechanical properties, and good melt fluidity in order to be processable. For the best composition, the scale-up in a semi-industrial extruder was then explored. Good results were achieved for the scaled-up composites; in fact, thanks to the extruder venting system, the residual moisture is efficiently removed, guaranteeing to the final composites improved mechanical and melt fluidity properties, when compared to the lab-scaled composites. Analytical models were also adopted to predict the trend of mechanical properties (in particular, tensile strength), also considering the effect of HSPs sizes and the role of the interfacial adhesion between the fillers and the matrix.
“…This MFR decrement is also reflected in the injection pressure increment during the injection molding process ( Table 2 ). The marked viscosity decrement observed during the lab-scale step is limited, thanks to the coupling of the low extruder residence time and the presence of the venting system connected to a vacuum pump that guarantees the humidity stripping during the melt extrusion, avoiding or limiting any eventual PLA degradation [ 49 , 50 ]. The mechanical results are noteworthy.…”
In this work, two different typologies of hazelnuts shell powders (HSPs) having different granulometric distributions were melt-compounded into poly(lactic acid) (PLA) matrix. Different HSPs concentration (from 20 up to 40 wt.%) were investigated with the aim to obtain final biocomposites with a high filler quantity, acceptable mechanical properties, and good melt fluidity in order to be processable. For the best composition, the scale-up in a semi-industrial extruder was then explored. Good results were achieved for the scaled-up composites; in fact, thanks to the extruder venting system, the residual moisture is efficiently removed, guaranteeing to the final composites improved mechanical and melt fluidity properties, when compared to the lab-scaled composites. Analytical models were also adopted to predict the trend of mechanical properties (in particular, tensile strength), also considering the effect of HSPs sizes and the role of the interfacial adhesion between the fillers and the matrix.
“…Furthermore, many researchers found similar results: Molinari, Giovanna et al showed that 9% microcrimped cellulose increases the crystallinity of PLA because it interacts with the amorphous phase of PLA and prevents glassy crystallization. 40 This effect has also been found in the literature, and it can be correlated to the partially amorphous cellulose that modifies the crystallinity of PLA, increasing the disorder of the molecular chain. 42 The OWF has a nucleating effect that can result in an increase in the crystallinity of the composite.…”
“…In the literature, the glass transition temperature of PLA is generally around 60°C. 40 Figure 6.DSC thermograms of the films PLA/OWF.…”
Section: Resultsmentioning
confidence: 99%
“…In the literature, the glass transition temperature of PLA is generally around 60°C. 40 DSC results showed a decrease value of glass transition temperature by adding OWF to the PLA matrix. The Tg of PLA drops to 40.08°C for OW10, it is clear that OWF lowers the Tg because it makes the chains more mobile in the matrix due to their plasticization.…”
Considerable interest has been shown in the development of biocomposite films for food packaging in recent years. In this study, biocomposite films based on polylactic acid (PLA) were prepared with varying levels of olive wood flour (OWF) (0, 1, 3, 5, and 10 wt%) using the solvent casting method. To achieve better dispersion, 2% ethanol was added during the casting of the biocomposite films. The effect of OWF content on the physicochemical and mechanical properties of the PLA films was investigated. Interaction between the OWF cellulose and the PLA matrix was revealed by FTIR spectroscopy analysis, and the addition of ethanol was found to be suitable for better dispersion of OWF, which resulted in decreased agglomeration rate in the biocomposites. The biocomposite films with the addition of 1% of OWF (OW1) exhibited the best dispersion, thermal stability, and tensile strength, with a gain of 31.07% (29.65 ± 6.6 MPa) and an increase in Young’s modulus of 15% (1199.18 ± 98 MPa). It was demonstrated that the properties of the PLA/OWF biocomposites make them suitable for green applications, including as film packaging for food products.
“…Regarding the application of coatings on plastic substrates, this is becoming increasingly necessary with the development of items with novel bio-based and biodegradable plastics based for example on poly (lactic acid) PLA, poly (butylene succinate) PBS, poly(butylene succinate-adipate) PBSA, as they do not show adequate barrier properties and are not able to withstand the rigours of the market [14][15][16][17]. In fact, since they do not present barrier properties comparable to traditional plastics [18], they need a protective layer.…”
The development of new bio-based coating materials to be applied on cellulosic and plastic based substrates, with improved performances compared to currently available products and at the same time with improved sustainable end of life options, is a challenge of our times. Enabling cellulose or bioplastics with proper functional coatings, based on biopolymer and functional materials deriving from agro-food waste streams, will improve their performance, allowing them to effectively replace fossil products in the personal care, tableware and food packaging sectors. To achieve these challenging objectives some molecules can be used in wet or solid coating formulations, e.g., cutin as a hydrophobic water- and grease-repellent coating, polysaccharides such as chitosan-chitin as an antimicrobial coating, and proteins as a gas barrier. This review collects the available knowledge on functional coatings with a focus on the raw materials used and methods of dispersion/application. It considers, in addition, the correlation with the desired final properties of the applied coatings, thus discussing their potential.
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