Montmorillonite-Starch based Nano-Composites and Applications

Development of synthetic biomaterials for skeletal reconstruction has progressed rapidly, driven partly by demand to reduce dependency on allografts. One class of materials, biopolymer nanocomposites, has shown promise when combined with additive manufacturing for these applications. The driving goal for the development of 3D-printable biopolymer nanocomposites composed of methacrylated monomers (triglycerides and triethylene glycol) and hydroxyapatite (HA) is to produce structurally robust and degradable customizable grafts. These materials must be able to withstand the loading conditions found invivo while allowing for degradation and remodeling processes. This study focused on the degradation potential of previously developed HA-containing biopolymer nanocomposites and the resulting consequences of degradation on their mechanical performance. One of the means to study a material's invivo degradation performance is to assess its susceptibility to oxidative degradation, as oxidation is naturally occurring in cell metabolism, inflammatory responses, and osteoclast resorption. Two invitro models of oxidative degradation were trialed: aqueous solutions of either hydrogen peroxide or neutral hypochlorous acid. Hypochlorous acid was shown to be a useful invitro assessment for the degradation potential of biomaterials to different reactive oxygen species. The biopolymer nanocomposites were clearly susceptible to oxidative degradation, demonstrating significant changes in mass and surface morphology. Mechanical performance was reduced under these testing conditions. This was attributed to three main factors: swelling and water absorption effects, chemical modifications, and loss of structure. Overall, this study provides insights into the effects of oxidative degradation on biomaterial functionality and highlights the importance of exploring relevant physiological effects on mechanical properties when developing biomaterials.

Biopolymer nanocomposites with customized mechanical property and exceptionally antibacterial performance

The aim of this study was to investigate the effects of cellulose nanofibrils and nanoclays on the mechanical, thermal, and morphological properties of polyhydroxybutyrate and polylactic acid bio-polymers. Polyhydroxybutyrate and polylactic acid as a polymer matrix and nanoclays and cellulose nanofibrils as reinforcing nano-fillers were used to prepare the biopolymer nanocomposites in twin screw extruder. Density, flexure strength and flexure modulus, tensile strength and tensile modulus, impact strength, thermal properties, and morphological characterization of the obtained biopolymer nanocomposites were determined. According to the obtained results, densities of the biopolymer nanocomposites were found to decrease with addition of the bio-fillers, and it was determined to be decreasing the density due to increasing the porosity in biopolymer nanocomposites. Although the increasing in the porosity of biopolymer nanocomposites was found in scanning electron microscope pictures, the mechanical properties of the biopolymer nanocomposites generally increased as compare with neat bio-polymers. Thermal analysis conducted with thermogravimetric-dynamic thermal analysis and differential scanning calorimeter showed that thermal stability of the biopolymer nanocomposites generally improved according to the neat bio-polymers.

The objective of this study was to evaluate the use of bagasse-activated charcoal for reduced formaldehyde emissions and their effect on the physical, mechanical, and biological properties of particleboard. Activated charcoal was made by carbonizing bagasse at 300°C for 2.5 h, followed by carbon activation using a 0.1M HCl solution for 24 h. Particleboards were made of a mixture of bagasse and wood particles with a ratio of 100:0, 75:25, 50:50, 25:75, and 0:100. The concentrations of activated charcoal used in manufacturing particleboards were 2, 4, and 6% based on the dry weight of the particles. Particleboards were made with a target density of 0.7 g/cm³ and hot-pressed at 140°C for 10 min with a pressure of 35 kg/cm2. The observed parameters were formaldehyde emission levels, physical properties, mechanical properties, and biological properties of particleboards. The results showed that the more activated charcoal added in the manufacture of particleboards decreased formaldehyde emissions of the panel. Based on the SNI 5008.2:2016, the overall formaldehyde emission value of particleboard in this study with activated charcoal is in the F* category. The addition of activated charcoal improved the physical, mechanical, and biological properties of particleboards in terms of increased density, decreased water content, water absorption, and thickness swelling, increased modulus of elasticity, modulus of rupture, internal bonding, and screw withdrawal, as well as increased resistance to termites. The particleboard with the addition of 6% activated charcoal showed better mechanical, physical, and biological properties. All physical and mechanical properties of particleboard met the JIS A 5908-2003 Type 8 standards, except for the modulus of elasticity. Keywords: Activated charcoal, bagasse, biological properties, formaldehyde emission, mechanical properties, particleboard, physical properties

This study investigated the mechanical, morphological, thermal, rheological properties, and accelerated aging performance of poly(lactic acid) (PLA)/polyhydroxybutyrate (PHB) blends with cellulose nanofibrils (CNFs) at low loading ratio. According to the obtained results, the addition of both PLA and CNFs were found to generally increase the mechanical properties of the biopolymer nanocomposites (BNCs). Morphological characterization with scanning electron microscopy (SEM) exhibited that cellular structure occurred in all the BNCs with adding both PLA and CNFs. Thermal stability of the BNCs improved with PLA and CNFs. The addition of CNFs and PLA generally increased the isotherms including Tg, Tc, and Tm according to differential scanning calorimetry (DSC), and it was found that the blends' crystallinity dropped because of a poor crystallinity of PLA. The addition of both PLA and CNFs provided an improvement on the rheological and viscoelastic properties of the neat PHB. XRD pattern of all the BNCs was found to be similar to the neat blends and the BNCs. In the accelerated weathering test, the adding PLA to neat PHB was found to provide more improvement than adding of CNFs.

Fourteen Angus heifers (210 +/- 6 kg initial BW) were allotted randomly to either a low P (LP: .12% P, DM basis) or an adequate P (AP: .20% P, DM basis) diet fed for 14 to 16 mo under drylot conditions on concrete floors to determine the influence of dietary P on chemical, physical, and mechanical properties of bone. Three weeks postpartum, after 14 to 16 mo on their diets, heifers were slaughtered and the right and left third metacarpals (McIII) were excised; soft tissue was removed and metacarpals were frozen in .9% saline. Metacarpals were subjected to a three-point flexure test using an Instron Testing Machine with a crossload speed of 50 mm/min to determine mechanical properties. Broken McIII were reassembled and a 2-cm section was removed at point of loading for determination of chemical and physical properties. Breaking load (BL) was greater (P less than .05) for McIII from the AP than for those from LP heifers (1,348 vs 1,179 kg). Breaking strength (BS) was greater (P less than .05) for AP than for LP heifers (202.5 vs 189.2 MPa). Animals receiving AP diets had greater (P less than .01) bone mineral content (12.6 vs 11.2 g/2-cm slice) and percentage of bone ash (68.0 vs 67.2%) than did LP animals. No differences (P greater than .10) were observed between treatment groups in Ca, P, or Mg percentage in bone ash. Circular, elliptical, radiographic, and planimeter area indices all were greater (P less than .05) in AP than in LP animals (1,048, 729, 1,069, and 570 vs 932, 660, 957, and 523 mm2, respectively). These data indicate that mechanical properties of bovine third metacarpals are sensitive to dietary P and reflect P status in the bovine. Mineral content of bone was highly correlated with its mechanical and physical properties.

The present chapter addresses the several characteristics of biopolymer nanocomposite in developing edible food packaging including sustainability, packaging attributes, active functionality, delivery systems, and improved food properties during storage life. The various nanostructured forms with the strategical synthesis mechanism for edible films and coatings have been discussed elaborately. Furthermore, the multifunctional property of biopolymer composites is a crucial factor in regard to offering enhanced packaging and food properties with a proper storage life of perishable food products. However, the considerable aspects of edible packaging fabrication are physical property, mechanical property, barrier property, thermal property, and others have been detailed in this chapter. The nanocomposite-based research has gained an extreme enthrallment for driving greener routes in packaging sectors as an alternate to the existing conventional plastic. In this regard, the recent advances of biopolymer composites available in developing edible films and coatings with an improved shelf life of food products have also been demonstrated.

The effects of physiologically relevant environmental conditions on the mechanical properties of 3D-printed biopolymer nanocomposites

For polymer composites as a filler material, Graphene is gaining tremendous importance in the recent year. Biopolymer nanocomposites reinforced with graphene as a filler (GRMs) or carbon nanotubes (CNTs) have been extensively explored for use as engineering materials in various applications, as they have low mass density exceptional mechanical properties. The most relevant sectors are the automotive and aerospace industries, in which various components have to be built by considering light-weight materials and along with this they have to have high strength, low cost and one of the important things is their recyclability One of the other important sector in which graphene plays an important role is in electronic components. They are used in manufacturing of photovoltaic cells, biosensors, Electromagnetic Interference shielding (EMI) and many more. This present chapter provides a better understanding of how graphene acts a better option for improving the properties of biopolymer nanocomposites used in various automotive and electronic components.

In deep‐earth engineering, the high earth temperature can significantly affect the rock's mechanical properties, especially when the rock is cooled during the construction process. Accordingly, whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated. The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800 °C. The mechanical and physical properties involved in this study included uniaxial compression strength, peak strain, modulus, P‐wave velocity, mass and volume, the change of which could reflect the sensitivity of granite to the cooling rate. Acoustic emission (AE) monitoring, microscopic observation, and X‐ray diffraction (XRD) are used to analyze the underlying damage mechanism. It is found that more AE signals and large‐scale cracks are accounted for based on the b‐value method when the specimens are cooled by water. Furthermore, the microscopic observation by polarized light microscopy indicates that the density, opening degree, and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode. In addition, the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures, which confirms that the change of mechanical properties is not related to the chemical properties. The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.

In this work, biopolymer nanocomposites derived from carboxymethyl chitosan (CMCS) and boehmite were prepared via an environmentally friendly technique and their structural, morphological, thermal, electrical, dielectric, and mechanical properties were investigated. The successful fabrication of carboxymethyl chitosan/boehmite nanocomposites was evident from the appearance of characteristic peaks of boehmite in FTIR and alteration in the morphology as revealed by optical and SEM micrographs. The glass transition temperature (Tg) and melting temperature (Tm) were increased as the filler content increased. The enhanced thermal stability of nanocomposites was clear from thermogravimetric results. The incorporation of boehmite nanoparticles into CMCS improved the conductivity to a semiconducting range. The dielectric constant of CMCS/boehmite nanocomposites was significantly higher compared to pure CMCS. The influence of temperature on AC conductivity, activation energy, dielectric constant and loss tangent were analyzed. Complex impedance analysis carried out by Nyquist plots and the bulk resistance showed a decreasing trend with temperature, which indicated enhanced conductivity with temperature. Tensile strength and hardness were observed to be increased with boehmite inclusion, whereas elongation at break is reduced. As a result, eco‐friendly CMCS/boehmite biopolymer nanocomposites with good thermal, mechanical, electric, and dielectric properties may be a potential green alternative for flexible electronic, charge storage, and other electrochemical devices.

Nanocomposites for food and beverage packaging

13 - Nanocomposites for food and beverage packaging

Abstract. A green and sustainable development in world is important and it needs to further strengthen at the moment. In this aspect, biopolymers, biopolymers nanocomposites with biodegradable properties are the best way for this purpose. Nanocellulose (NC) is a biopolymer and can be produced from natural resources like various plant species and agricultural waste products including rice husk, tea leaves, sugarcane bagasse and so forth. Due to their special properties such as biodegradability, renewability, biocompability, low cost and outstanding mechanical capabilities, NC have gained increased research and application interests. This review provided detail information about the production, structure and properties of NC. The usage of NC as reinforcement materials for different types of biopolymers are presented in the review. The surface modification of NC for better dispersion and better interaction of NCs in polymer matrices, the mechanical and thermal properties of the NC biopolymers nanocomposites are discussed.

It is expected that biopolymers obtained from renewable resources will in due course become fully competitive with fossil fuel-derived plastics as food-packaging materials. In this context, biopolymer nanocomposites are a field of emerging interest since such materials can exhibit improved mechanical and barrier properties and be more suitable for a wider range of food-packaging applications. Natural or synthetic clay nanofillers are being investigated for this purpose in a project called NanoPack funded by the Danish Strategic Research Council. In order to detect and characterize the size of clay nanoparticulates, an analytical system combining asymmetrical flow field-flow fractionation (AF4) with multi-angle light-scattering detection (MALS) and inductively coupled plasma mass spectrometry (ICP-MS) is presented. In a migration study, we tested a biopolymer nanocomposite consisting of polylactide (PLA) with 5% Cloisite®30B (a derivatized montmorillonite clay) as a filler. Based on AF4-MALS analyses, we found that particles ranging from 50 to 800 nm in radius indeed migrated into the 95% ethanol used as a food simulant. The full hyphenated AF4-MALS-ICP-MS system showed, however, that none of the characteristic clay minerals was detectable, and it is concluded that clay nanoparticles were absent in the migrate. Finally, by means of centrifugation experiments, a platelet aspect ratio of 320 was calculated for montmorillonite clay using AF4-MALS for platelet size measurements.