Influence of Epoxidized Canola Oil (eCO) and Cellulose Nanocrystals (CNCs) on the Mechanical and Thermal Properties of Polyhydroxybutyrate (PHB)—Poly(lactic acid) (PLA) Blends
Abstract:Two major obstacles to utilizing polyhydroxybutyrate (PHB)—a biodegradable and biocompatible polymer—in commercial applications are its low tensile yield strength (<10 MPa) and elongation at break (~5%). In this work, we investigated the modification of the mechanical properties of PHB through the use of a variety of bio-derived additives. Poly(lactic acid) (PLA) and sugarcane-sourced cellulose nanocrystals (CNCs) were proposed as mechanical reinforcing elements, and epoxidized canola oil (eCO) was utilized… Show more
“…In the low frequency region, a homopolymer typically presents a decline of 2, whereas for ABS, which is a copolymer, the drop is smaller than 2. 20 In addition, the CNC 150 /ABS nanocomposites displayed viscoelastic response similar to pure ABS, therefore, no significant structural modification is apparent. Figure 4.Storage modulus (G′) versus loss modulus (G″) for pure ABS and the nanocomposites.…”
The use of cellulose nanocrystals as reinforcement in polymers brings challenges mainly related to the dry thermal processing, and their adhesion and dispersion in the matrix. In this work, cellulose nanocrystals from sugarcane bagasse was used as reinforcement in nanocomposites of acrylonitrile-butadiene-styrene. Thus, the main objective of this work is to evaluate the mechanical and thermal performance of cellulose nanocrystals/acrylonitrile-butadiene-styrene (CNC/ABS) nanocomposites as a function of cellulose nanocrystals type and content. More specifically, to study the effects of the chemical interaction between acrylonitrile groups from ABS and hydroxyl groups from cellulose. The ABS and the nanocomposites, reinforced with 0.5, 1.0 and 1.5 wt% nanocrystals, were obtained by extrusion and then injection molded to obtain specimens for testing. Mechanical testing, dynamic mechanical analysis, rheology and thermogravimetric analysis were used for characterization. The main results are related to increased impact strength, elastic modulus, storage modulus and viscosity of the nanocomposite compared to ABS. However, tensile strength and thermal stability decreased. Therefore, if higher tensile properties are needed, the CNC220/ABS nanocomposites should be preferred whereas, for impact, CNC150/ABS. Thus, there is a general improvement in properties up to 0.5% cellulose nanocrystals content, which is followed by a loss in properties for higher content.
“…In the low frequency region, a homopolymer typically presents a decline of 2, whereas for ABS, which is a copolymer, the drop is smaller than 2. 20 In addition, the CNC 150 /ABS nanocomposites displayed viscoelastic response similar to pure ABS, therefore, no significant structural modification is apparent. Figure 4.Storage modulus (G′) versus loss modulus (G″) for pure ABS and the nanocomposites.…”
The use of cellulose nanocrystals as reinforcement in polymers brings challenges mainly related to the dry thermal processing, and their adhesion and dispersion in the matrix. In this work, cellulose nanocrystals from sugarcane bagasse was used as reinforcement in nanocomposites of acrylonitrile-butadiene-styrene. Thus, the main objective of this work is to evaluate the mechanical and thermal performance of cellulose nanocrystals/acrylonitrile-butadiene-styrene (CNC/ABS) nanocomposites as a function of cellulose nanocrystals type and content. More specifically, to study the effects of the chemical interaction between acrylonitrile groups from ABS and hydroxyl groups from cellulose. The ABS and the nanocomposites, reinforced with 0.5, 1.0 and 1.5 wt% nanocrystals, were obtained by extrusion and then injection molded to obtain specimens for testing. Mechanical testing, dynamic mechanical analysis, rheology and thermogravimetric analysis were used for characterization. The main results are related to increased impact strength, elastic modulus, storage modulus and viscosity of the nanocomposite compared to ABS. However, tensile strength and thermal stability decreased. Therefore, if higher tensile properties are needed, the CNC220/ABS nanocomposites should be preferred whereas, for impact, CNC150/ABS. Thus, there is a general improvement in properties up to 0.5% cellulose nanocrystals content, which is followed by a loss in properties for higher content.
“…The GPC method is described in our previous work. [51] Large scale graphite flakes were purchased from Alfa Aesar Inc. Sulfuric acid (98%), hydrogen peroxide (30%), phosphoric acid (98%), hydrochloric acid (37%), and potassium permanganate particles were purchased from Fisher Scientific, Canada and used as received. Glacial acetic acid (99%), l-ascorbic acid (l-A.A) were provided from Sigma-Aldrich, Canada, and used as received.…”
Accurate monitoring of physiological temperatures is important for the diagnosis and tracking of various medical conditions. This work presents the design, fabrication, and characterization of temperature sensors using conductive polymer composites (CPCs) patterned on both flexible and stretchable substrates through both drop coating and direct ink writing (DIW). These composites were formed using a high melting point biopolymer polyhydroxybutyrate (PHB) as the matrix and the graphenic nanomaterial reduced graphene oxide (rGO) as the nanofiller (from 3 to 12 wt%), resulting in a material that exhibits a temperature-dependent resistivity. At room temperature the composites exhibited electrical percolation behavior. Around the percolation threshold, both the carrier concentration and mobility were found to increase sharply. Sensors were fabricated by drop-coating PHB-rGO composites onto ink-jet printed silver electrodes. The temperature coefficient of resistance was determined to be 0.018 /°C for pressed rGO powders and 0.008 /°C for the 3 wt% samples (the highest responsivity of all composites). Composites were found to have good selectivity to temperature with respect to pressure and moisture. Thermal mapping was demonstrated using 6 × 7 arrays of sensing elements. Stretchable devices with a meandering pattern were fabricated using DIW, demonstrating the potential for these materials in healthcare monitoring devices.
“…The results showed that after seven days of aging, the crystallinity of the PHB sample increased from the initial 20.5% to 28.2%. This change in the material could impact its overall mechanical properties, since the degree of crystallinity increases, it will influence the impact resistance, the young's modulus and elongation at break [92,93]. In another study by Srubar et al, samples of PHB were isothermally conditioned at 15 • C in a desiccated environment for 168 days in order to investigate the effects of aging at storage temperatures slightly above the Tg of the material.…”
Plastic pollution is fueling the grave environmental threats currently facing humans, the animal kingdom, and the planet. The pursuit of renewable resourced biodegradable materials commenced in the 1970s with the need for carbon neutral fully sustainable products driving important progress in recent years. The development of bioplastic materials is highlighted as imperative to the solutions to our global environment challenges and to the restoration of the wellbeing of our planet. Bio-based plastics are becoming increasingly sustainable and are expected to substitute fossil-based plastics. Bioplastics currently include both, nondegradable and biodegradable compositions, depending on factors including the origins of production and post-use management and conditions. Among the most promising materials being developed and evaluated is polyhydroxybutyrate (PHB), a microbial bioprocessed polyester belonging to the polyhydroxyalkanoate (PHA) family. This biocompatible and non-toxic polymer is biosynthesized and accumulated by a number of specialized bacterial strains. The favorable mechanical properties and amenability to biodegradation when exposed to certain active biological environments, earmark PHB as a high potential replacement for petrochemical based polymers such as ubiquitous high density polyethylene (HDPE). To date, high production costs, minimal yields, production technology complexities, and difficulties relating to downstream processing are limiting factors for its progression and expansion in the marketplace. This review examines the chemical, mechanical, thermal, and crystalline characteristics of PHB, as well as various fermentation processing factors which influence the properties of PHB materials.
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