Mejora de la termoconformabilidad del PHBV mediante mezclas biodegradables con poliuretano

Actas del Congreso publicadas por ed. Compobell. ISBN 978-84-942655-8-7Mezclas de poli (3-hidroxibutirato-co-3-hidroxivalerato) (PHBV) y poliuretano termoplástico (TPU) se obtuvieron mediante extrusión con el objetivo de mejorar la procesabilidad del PHBV. La morfología, las propiedades mecánicas y la termoconformabilidad del PHBV se han evaluado observándose un aumento en la elongación a rotura y una mejora en el termoconformado del PHBV.A number of samples of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and thermoplastic polyurethane (TPU) were obtained through extrusion, with the aim of improving the processability of PHBV. The relevant assessment of PHBV’s morphology, mechanic properties, and thermoformability has been carried out, observing an increase in elongation at break and an improvement in the thermoforming of PHBV.Ministerio de Economía y Competitividad (proyecto MAT2012-38947-C02-01), Generalitat Valenciana (GV/2014/123) y Pla de Promoció de la Investigació de la Universitat Jaume I (PREDOC/2012/32)

Toughness Enhancement of Commercial Poly (Hydroxybutyrate-co-Valerate) (PHBV) by Blending with a Thermoplastic Polyurethane (TPU)

Poly(hydroxyl butyrate-co-valerate) (PHBV) is a biopolymer synthesized by microorganisms that is fully biodegradable with improved thermal and tensile properties with respect to some commodity plastics. However, it presents an intrinsic brittleness that limits its potential application in replacing plastics in packaging applications. Films made of blends of PHBV with different contents of thermoplastic polyurethane (TPU) were prepared by single screw extruder and their fracture toughness behavior was assessed by means of the essential work of fracture (EWF) Method. As the crack propagation was not always stable, a partition method has been used to compare all formulations and to relate results with the morphology of the blends. Indeed, fully characterization of the different PHBV/TPU blends showed that PHBV was incompatible with TPU. The blends showed an improvement of the toughness fracture, finding a maximum with intermediate TPU contents.Financial support for this research from Ministerio de Economía y Competitivi dad (project AGL2015-63855-C2-2-R (MINECO/FEDER) and Pla de Promoció de la Investigació de la Universitat Jaume I (PREDOC/2012/32 and E-2015-22) is gratefully acknowledged

Effect of the Purification Treatment on the Valorization of Natural Cellulosic Residues as Fillers in PHB-Based Composites for Short Shelf Life Applications

This is a pre-print of an article published in Waste and Biomass Valorization. The final authenticated version is available online at: https://doi.org/10.1007/s12649-020-01192-1In this work the effect of a combined NaOH + peracetic acid (PAA) purification treatment on the valorization of almond shell (AS) and rice husk (RH) lignocellulosic residues as fillers in PHB-based composites for short shelf life applications has been studied. The efficiency of the treatment at removing the non-cellulosic components of the fibers has been evaluated by SEM, FTIR, WAXS and TGA taking a commercial cellulose as reference. The influence of the untreated and treated fibers on the morphology, thermal, crystallization, tensile properties, fracture toughness and dynamo mechanical behavior of the PHB/fiber composites has been studied. The treatment has demonstrated its ability at removing the lignin, hemicelluloses and waxes allowing the obtention of fibers with relative crystallinity, thermal stability and composition similar to the commercial cellulose. The different agro-food based lignocellulosic residues used resulted in two suitable reinforcing fillers for a PHB matrix. Hence, composites prepared with the treated fibers presented better thermal and mechanical performance than those prepared with the untreated ones. Therefore, the so-obtained purified residue fibers are comparable to a pure cellulose as a filler for PHB composites

Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)/ Purifi ed Cellulose Fiber Composites by Melt Blending: Characterization and Degradation in Composting Conditions

Novel biodegradable composites based on poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) and different contents of purifi ed alpha-cellulose fi bers (3, 10, 25 and 45%) were prepared by melt blending and characterized. The composites were characterized by scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS) experiments, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanic analysis (DMA) and Shore D hardness measurements. Disintegrability under composting conditions was studied according to the ISO 20200 standard. Morphological results showed that high dispersion of the fi bers was achieved during mixing. Good adhesion on the fi ber-matrix interface was also detected by SEM. The addition of low and medium cellulose contents did not result in lower thermal resistance with respect to the neat PHBV. A reinforcing effect of the cellulose fi bers was detected in all samples, this effect being more pronounced at high temperatures. The composting results show that the addition of the fi bers did not affect the disintegrability of the PHBV, and thus compostable “green” low-cost PHBV/cellulose composites can be obtained

Assessing the thermoformability of poly(3-hydroxybutyrate-co-3- hydroxyvalerate)/poly(acid lactic) blends compatibilized with diisocyanates

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a renewable alternative to conventional barrier packaging polymers due to its thermoplastic properties, biodegradability and gas barrier performance but its potential industrial applications are limited by its high price and difficult processability. A thorough study concerning the thermoforming ability of PHBV, and blends with poly(lactic acid) (PLA) incorporating three different diisocyanates as compatibilizers (hexamethylene diisocyanate, poly(hexamethylene) diisocyanate and 1,4-phenylene diisocyanate) is herein presented after component melt blending. A straightforward universal qualitative method is proposed to assess the thermoformability, based on a visual inspection of a thermoformed specimen and the ability to reproduce the mold shape, and the thermoforming window of the material. The results reveal a significant improvement in the thermoforming capacity and a widening of the thermoforming windows as the correct amounts of diisocyanates are incorporated. The barrier properties and the biodisintegrability of the blends was also studied, confirming a predictable slight decrease of the barrier performance when PLA is added, but without negatively affecting the disintegrability under composting conditions with respect to pristine PHBV

Study of the Compatibilization Effect of Different Reactive Agents in PHB/Natural Fiber-Based Composites

Fiber–matrix interfacial adhesion is one of the key factors governing the final properties of natural fiber-based polymer composites. In this work, four extrusion reactive agents were tested as potential compatibilizers in polyhydroxylbutyrate (PHB)/cellulose composites: dicumyl peroxide (DCP), hexamethylene diisocyanate (HMDI), resorcinol diglycidyl ether (RDGE), and triglycidyl isocyanurate (TGIC). The influence of the fibers and the different reactive agents on the mechanical properties, physical aging, and crystallization behavior were assessed. To evaluate the compatibilization effectiveness of each reactive agent, highly purified commercial cellulose fibers (TC90) were used as reference filler. Then, the influence of fiber purity on the compatibilization effect of the reactive agent HMDI was evaluated using untreated (U_RH) and chemically purified (T_RH) rice husk fibers, comparing the results with the ones using TC90 fibers. The results show that reactive agents interact with the polymer matrix at different levels, but all compositions showed a drastic embrittlement due to the aging of PHB. No clear compatibilization effect was found using DCP, RDGE, or TGIC reactive agents. On the other hand, the fiber–polymer interfacial adhesion was enhanced with HMDI. The purity of the fiber played an important role in the effectiveness of HMDI as a compatibilizer, since composites with highly purified fibers showed the greatest improvements in tensile strength and the most favorable morphology. None of the reactive agents negatively affected the compostability of PHB. Finally, thermoformed trays with good mold reproducibility were successfully obtained for PHB/T_RH/HMDI composition

Role of Plasticizers on PHB/bio-TPE Blends Compatibilized by Reactive Extrusion

Poly(hydroxybutyrate) (PHB) is a biopolymer biologically synthesized by controlled bac- terial fermentation from a wide variety of microorganisms. PHB is proposed as a potential green alternative to commonly used plastics in packaging, due to its biodegradability and biocompatibility. However, if PHB is to replace commodities, it has some limitations regarding its thermo-mechanical performance to overcome. Among them are its critically the low toughness values at room tem- perature and poor thermoforming ability. With the aim of overcoming these weaknesses, in this work, blends of PHB with the addition of a biodegradable thermoplastic elastomer (bio-TPE) were prepared and evaluated. Films of such compounds were made by cast extrusion. In order to enhance the compatibility of both polymers during the extrusion process, three different reactive agents (poly-hexametylene diisocianate, triglycidyl isocyanurate, and Joncryl® ADR-4368) were assessed. The morphology and mechanical- and thermal properties of the films obtained were analyzed. In addition, the thermoforming ability of the produced films was evaluated. The results show that the plasticizers present in the bio-TPE interacted with the reactive agents, making them chemical competitors and altering the outcome of the blends

Biocomposites of different lignocellulosic wastes for sustainable food packaging applications

The suitability of three local lignocellulosic wastes i.e. almond shell (AS), rice husk (RH) and seagrass (SG) as fillers in PHB/Fiber composites applications has been studied. PHB/Fiber composites with 10 phr and 20 phr fiber content were prepared by melt blending. The influence of the fiber type (size, morphology and origin) and content on the morphological, mechanical and thermal properties of the as obtained composites has been assessed. To evaluate the potential use in food packaging applications, the barrier performance to water, thermoforming ability and disintegration in controlled composting conditions of the composites were also studied. All the fibers have demonstrated to be apt for their use as fillers in PHB/Fiber composites, showing a reinforcing effect without affecting the crystallinity and the disintegration rate of PHB. The thermal stability and the water barrier performance of the composites were reduced by the presence of the fibers. Nevertheless, the addition of AS resulted in the best balance of properties, in terms of permeability and mechanical properties, finding an enhancement of the thermoforming ability of PHB when 10 phr of AS was added

Desarrollo y caracterización de compuestos biodegradables basados en polihidroxialcanoatos y fibras lignocelulósicas para aplicaciones de un solo uso

Esta tesis se ha centrado en la obtención y caracterización de compuestos basados en polihidroxialcanoatos (PHA) y fibras de origen lignocelulósico con el objetivo de obtener materiales compostables de coste reducido encaminados a aplicaciones de corta vida útil como el envasado o el desarrollo de productos desechables (cubertería de un solo uso, pajitas, etc.). Empleando como materiales de base polihidroxibutirato (PHB) y poli(hidroxibutirato-co-hidroxivalerato) (PHBV) se han obtenido compuestos mediante la adición de fibras de origen lignocelulósico tanto comerciales (TC90), como procedentes de residuos vegetales (AS, RH, SG). Se ha estudiado la adición de una fase elastomérica como modificador de impacto (TPU) con el fin de mejorar la tenacidad en sistemas PHBV/TC90. Se ha evaluado la eficiencia de distintos agentes reactivos como compatibilizantes de las distintas fases tanto en los sistemas dobles (PHA/fibra) como en los triples (PHBV/TPU/TC90).This thesis has focused on the development and characterization of composites based on polyhydroxyalkanoates (PHA) and lignocellulosic fibers with the aim of obtaining reduced cost compostable materials for short shelf life applications such as packaging or single use products (cutlery, straws, etc.). Composites have been obtained using polyhydroxybutyrate (PHB) or poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) as the base materials and lignocellulosic fibers as fillers. The fibers used have been both commercial (TC90) and obtained from vegetal wastes (AS,RH and SG). The addition of an elastomeric phase as an impact modifier (TPU) has been studied in order to improve the toughness of the PHBV/TC90 systems. The efficiency of different reactive agents as compatibilizers in the double (PHA / fiber) and triple systems(PHBV / TPU / TC90) has been also evaluated.Programa de Doctorat en Tecnologies Industrials i Material

Toughness Enhancement of PHBV/TPU/Cellulose Compounds with Reactive Additives for Compostable Injected Parts in Industrial Applications

Poly(3-hydroxybutyrate-co-3-valerate), PHBV, is a bacterial thermoplastic biopolyester that possesses interesting thermal and mechanical properties. As it is fully biodegradable, it could be an alternative to the use of commodities in single-use applications or in those intended for composting at their end of life. Two big drawbacks of PHBV are its low impact toughness and its high cost, which limit its potential applications. In this work, we proposed the use of a PHBV-based compound with purified α-cellulose fibres and a thermoplastic polyurethane (TPU), with the purpose of improving the performance of PHBV in terms of balanced heat resistance, stiffness, and toughness. Three reactive agents with different functionalities have been tested in these compounds: hexametylene diisocianate (HMDI), a commercial multi-epoxy-functionalized styrene-co-glycidyl methacrylate oligomer (Joncryl® ADR-4368), and triglycidyl isocyanurate (TGIC). The results indicate that the reactive agents play a main role of compatibilizers among the phases of the PHBV/TPU/cellulose compounds. HMDI showed the highest ability to compatibilize the cellulose and the PHBV in the compounds, with the topmost values of deformation at break, static toughness, and impact strength. Joncryl® and TGIC, on the other hand, seemed to enhance the compatibility between the fibres and the polymer matrix as well as the TPU within the PHBV