Bio-Composites Reinforced with Strontium Titanate Nanoparticles: Mechanical Behavior and Degradability (original) (raw)
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On the Mechanical and Dielectric Properties of Biocomposites Containing Strontium Titanate Particles
Ferroelectrics and Their Applications, 2018
In recent years, scientists advanced the study of bio-ferroelectric composites to develop new environmentally friendly and inexpensive electronic elements such as capacitors, actuators, and transistors. Accordingly, the present research relates to composites made of chitosan-cellulose polymeric matrix and strontium titanate (STO) nanoparticles. The variables considered include different percentages of cellulose (15 and 25 v%) and strontium titanate nanoparticles (10 and 20 wt%). The electrical characterization of the composites included measuring their dielectric constant, current density, and conductivity. The results suggest that the addition of STO nanoparticles raised the dielectric constant while lowering the current density and the conductivity of the nanocomposites. Moreover, although the cellulose addition increased the current density and the conductivity of the composites, it lowered their dielectric constant. Also, the resulting biocomposite capacitors could withstand up to 60 V without any detectable dielectric breakdown. The other two properties measured were the ultimate tensile strength (UTS) and the degradation temperature (Tdeg). Higher percentages of cellulose decreased the UTS and the Tdeg of the chitosan-cellulose composites while the addition of cellulose slightly raised these properties of the composites made of chitosan-cellulose and STO nanoparticles. The results proved that these types of biocomposites are apt as capacitors with adequate strength to withstand aggressive environments. This work was fully conducted in the facilities of the Nanotechnology Center hosted by the
Materials Sciences and Applications, 2021
In recent years, there has been a growing discussion about the problems related to the massive use of many synthetic plastic materials, which inevitably leads to an increase in environmental pollution caused by the inappropriate disposal of these materials. In this sense, biodegradable materials have been a subject of great interest, as they are a real alternative to replace these materials and tackle this issue. In this work, fully biodegradable composites were prepared by solution casting method. Microcrystalline cellulose (MCC) and treated microcrystalline cellulose (TMCC) were separately incorporated into biodegradable PLA and PHB matrices at ratios of 3, 5 and 7 wt% and the properties of the obtained biocomposites were evaluated by TGA, DSC, XRD and TD-NMR. From thermal analyses, it was seen that TMCC resulted in better thermal stability and 3 wt% of filler, in general, promoted a more pronounced thermal improvement. Furthermore Tg, Tc and Tm remained practically unchanged after MCC and TMCC addition. From XRD it was seen that the cellulose fillers influence in different ways the matrices, promoting increase or decrease in the degree of crystallinity. Finally, the results obtained by TD-NMR showed a decrease in the T 1 H values for all prepared biocomposites, indicating a good dispersion of the cellulose fillers in the matrices and pointed that the systems containing 3 wt% of cellulose fillers were the most homogeneous formulations.
Journal of Applied Polymer Science, 2012
Biodegradable nanocomposites of cellulose acetate phthalate and chitosan reinforced with functionalized nanoclay (NC) were prepared. The NC loading was varied from 0 to 10%. The mechanical and thermal properties have been investigated for these composites. The nanocomposites exhibited enhanced mechanical properties due to the addition of NC. The scanning electron micrographs of the blend specimens also support the above observations. Thermogravimetric analyses were carried out to assess the degradation stability of the blends. The blend shows an increase in the rate of biodegradation and water uptake with higher loading of NC. The exfoliation of NC was analyzed by X-ray diffraction studies. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125: E16-E26, 2012 Figure 12 Biodegradation: variation of percentage weight loss with number of days for CAP-chitosan-NC blends.
Nanobioceramic Composites: A Study of Mechanical, Morphological, and Thermal Properties
BioResources, 2013
The aim of this study was to explore the incorporation of biomass carbon nanofillers (CNF) into advanced ceramic. Biomass from bamboo, bagasse (remains of sugarcane after pressing), and oil palm ash was used as the predecessor for producing carbon black nanofillers. Furnace pyrolysis was carried out at 1000 °C and was followed by ball-mill processing to obtain carbon nanofillers in the range of 50 nm to 100 nm. CNFs were added to alumina in varying weight fractions and the resulting mixture was subjected to vacuum sintering at 1400 °C to produce nanobioceramic composites. The ceramic composites were characterized for mechanical, thermal, and morphological properties. A high-resolution Charge-coupled device (CCD) camera was used to study the fracture impact and the failure mechanism. An increase in the loading percentage of CNFs in the alumna decreased the specific gravity, vickers hardness (HV), and fracture toughness values of the composite materials. Furthermore, the thermal conductivity and the thermal stability of the ceramic composite increased as compared to the pristine alumina.
Optimization of the Mechanical Performance of Bacterial Cellulose/Poly (l-lactic) Acid Composites
… Applied Materials & …, 2009
Understanding the nature of the interface between nanofibers and polymer resins in composite materials is challenging because of the complexity of interactions that may occur between fibers and between the matrix and the fibers. The ability to select the most efficient amount of reinforcement for stress transfer, making a saving on both cost and weight, is also a key part of composite design. The use of Raman spectroscopy to investigate micromechanical properties of laminated bacterial cellulose (BC)/poly(L-lactic) acid (PLLA) resin composites is reported for the first time as a means for understanding the fundamental stress-transfer processes in these composites, but also as a tool to select appropriate processing and volume fraction of the reinforcing fibers. Two forms of BC networks are investigated, namely, one cultured for 3 days and another for 6 days. The mechanical properties of the latter were found to be higher than the former in terms of Young's modulus, stress at failure, and work of fracture. However, their specific Young's moduli (divided by density) were found to be similar. Young's modulus and stress at failure of transparent predominantly amorphous PLLA films were found to increase by 100 and 315%, respectively, for an 18% volume fraction of BC fibers. BC networks cultured for 3 days were shown to exhibit enhanced interaction with PLLA because of their higher total surface area compared, as measured by nitrogen adsorption, to the material cultured for 6 days. This enhanced interaction is confirmed by using the Raman spectroscopic approach, whereby larger band shift rates, of a peak initially located at 1095 cm -1 , with respect to both strain and stress, are observed, which is a quantitative measure of enhanced stress transfer. Thermal analysis (differential scanning calorimetry) and electron microscopy imaging (scanning electron microscopy) of the samples also confirms the enhanced coupling between the resin and the BC networks cultured for 3 days, compared to those cultured for 6 days. These results are shown to have implications for the use of BC networks for composite reinforcement, whereby less material can be used for the same specific mechanical properties. The technique also gives opportunities to study the interfaces in these composite materials in detail.
A Study on Thermal and Nanomechanical Performance of Cellulose Nanomaterials (CNs)
Materials
Wood-based cellulose nanomaterials (CNs) (specifically, cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs)) are environmentally sourced low-impact materials with remarkable thermal, mechanical, and physical properties. This uniqueness makes them great candidates for creating nanocomposite materials with a wide range of attributes. Investigating the morphological, thermal, and nanomechanical properties of CNs becomes crucial to intelligent development of novel composite materials. An atomic force microscope equipped with a nanoindenter was used to investigate the compression modulus of CNFs and CNCs using two analytical approaches (denoted as Oliver Pharr (OP) and Fused Silica (FS)). The CNC modulus values (E CNC-FS = 21.1 GPa, E CNC-OP = 28.7 GPa) were statistically larger than those obtained from CNFs (E CNF-FS = 12.4 GPa, E CNF-OP = 15.1 GPa). Additionally, the FS analytical approach provided statistically significant lower estimates. Thermal stability of CNFs and CNCs was investigated using thermogravimetric analysis. Significant differences were found between CNF and CNC onset temperatures (Onset CNC = 228.2 • C, Onset CNF = 279.9 • C), decomposition temperatures (DTGA CNC = 247.9 • C, DTGA CNF = 331.4 • C), and residues (Residue CNC = 34.4%, Residue CNF = 22.8%). This research enriches the information on thermal stability and nanomechanical performance of cellulose nanomaterials, and provides increased knowledge on understanding the effect of CNs as a matrix or reinforce in composites.
Journal of Materials Science, 2014
Thermoplastic starch (TPS) matrix was reinforced with various kenaf bast cellulose nanofiber loadings (0-10 wt%). Thin films were prepared by casting and evaporating the mixture of aqueous suspension of nanofibers (NFs), starch, and glycerol which underwent gelatinization process at the same time. Moreover, raw fibers (RFs) reinforced TPS films were prepared with the same contents and conditions. The effects of filler type and loading on different characteristics of prepared materials were studied using transmission and scanning electron microscopies, X-ray diffractometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and moisture absorption analysis. Obtained results showed a homogeneous dispersion of NFs within the TPS matrix and strong association between the filler and matrix. Moreover, addition of nanoreinforcements decreased the moisture sensitivity of the TPS film significantly. About 20 % decrease in moisture content at equilibrium was observed with addition of 10 wt% NFs while this value was only 5.7 % for the respective RFs reinforced film.
Cellulose reinforced polymer composites and nanocomposites: a critical review
Cellulose, 2013
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Journal of Southwest Jiaotong University, 2021
Poly(e-caprolactone) are synthetic biodegradable polymers that can potentially be used as biocompatible materials for biological applications. The purpose of this work was to investigate the effect of acetylated cellulose nanocrystals isolated from corncob waste loaded into poly(e-caprolactone) matrix blend on its thermal, mechanical, morphology, and crystallinity. The acetylated cellulose nanocrystal filler with various concentrations (namely 5, 10, 15, and 20%) was mixed with poly(e-caprolactone) matrix prepared using reflux method under N2 gas flow at 120oC for 10 min. Subsequently, the samples was characterized by thermal gravimetric analysis, DSC, tensile, Fourier transform infrared spectroscopy, tunneling electron microscope, SEM, and XRD to determine the thermal, mechanical, functional group, particle size, morphology, and crystallinity, respectively. Thermal gravimetric analysis and DSC analysis revealed that the thermal stability of poly(e-caprolactone) improved and the deg...