scholarly journals Structure and Properties of Polylactic Acid Biocomposite Films Reinforced with Cellulose Nanofibrils

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3306
Author(s):  
Qianqian Wang ◽  
Chencheng Ji ◽  
Jianzhong Sun ◽  
Qianqian Zhu ◽  
Jun Liu
Keyword(s):  
Polylactic Acid ◽  
Cellulose Nanofibrils ◽  
Nitrogen Atmosphere ◽  
Scanning Calorimetry ◽  
Enzymatic Pretreatment ◽  
Thermogravimetric Analyzer ◽  
Degradation Temperature ◽  
Biocomposite Films ◽  
Renewable Feedstock ◽  
Vis Spectroscopy

Polylactic acid (PLA) is one of the most promising biodegradable and recyclable thermoplastic biopolymer derived from renewable feedstock. Nanocellulose reinforced PLA biocomposites have received increasing attention in academic and industrial communities. In the present study, cellulose nanofibrils (CNFs) was liberated by combined enzymatic pretreatment and high-pressure homogenization, and then subsequently incorporated into the PLA matrix to synthesize PLA/CNF biocomposite films via solution casting and melt compression. The prepared PLA/CNF biocomposite films were characterized in terms of transparency (UV-Vis spectroscopy), chemical structure (attenuated total reflectance-Fourier transform infrared, ATR-FTIR; X-ray powder diffraction, XRD), thermal (thermogravimetric analyzer, TGA; differential scanning calorimetry, DSC), and tensile properties. With 1.0–5.0 wt % additions of CNF to the PLA matrix, noticeable improvements in thermal and physical properties were observed for the resulting PLA/CNF biocomposites. The 2.5 wt % addition of CNF increased the tensile strength by 8.8%. The Tonset (initial degradation temperature) and Tmax (maximum degradation temperature) after adding 5.0 wt % CNF was increased by 20 °C, and 10 °C, respectively in the nitrogen atmosphere. These improvements were attributed to the good dispersibility and improved interfacial interaction of CNF in the PLA matrix.

scholarly journals Evaluation of Nanocomposite Made of Polylactic Acid and Nanocellulose from Carrot Pomace Modified with Silver Nanoparticles

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 812 ◽  
Author(s):  
Monika Szymańska-Chargot ◽  
Monika Chylińska ◽  
Piotr M. Pieczywek ◽  
Anna Walkiewicz ◽  
Giorgia Pertile ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Silver Nanoparticles ◽  
Polylactic Acid ◽  
Cellulose Nanofibrils ◽  
Antibacterial Properties ◽  
Young Modulus ◽  
Transmission Rates ◽  
Degradation Temperature

In this research, it was proposed to use carrot cellulose nanofibrils (CCNF) isolated from carrot pomace modified with silver nanoparticles (AgNPs) as a filler of polylactic acid (PLA) composites matrix. The new procedure was based on two steps: first, the preparation of nanocellulose modified with metal nanoparticles, and then the combination with PLA. Two concentrations—0.25 mM and 2 mM—of AgNO3 were used to modify CCNF. Then, PLA was mixed with the filler (CCNF/AgNPs) in two proportions 99:1 and 96:4. The influence of CCNF/AgNPs on mechanical, hydrophilic, thermal, and antibacterial properties of obtained nanocomposites was evaluated. The greatest improvement of mechanical properties was observed for composite containing CCNF with 2 mM of AgNPs, which obtained the lowest Young modulus and highest strain at break. The degradation temperature was lower for PLA with CCNF/AgNPs, but crystallization temperature wasn’t influenced. The addition of CCNF/AgNPs also increased hydrophilicity. The transmission rates of oxygen, nitrogen, and carbon dioxide also increased after the addition of CCNF/AgNPs to PLA. The antibacterial function against Escherichia coli and Bacillus cereus was obtained after the addition of AgNPs but only at the contact surface with the material made, suggesting the lack of migration of nanoparticles from the composite.

Physical, Mechanical, and Thermal Properties of Sisal Cellulose Biocomposite Films

2012 ◽  
Vol 488-489 ◽  
pp. 1016-1020 ◽  
Author(s):  
Sayamon Somsub ◽  
Duangdao Aht-Ong
Keyword(s):  
Composite Films ◽  
Short Fiber ◽  
Sisal Fiber ◽  
Mechanical And Thermal Properties ◽  
Solvent Casting ◽  
Complex Solution ◽  
Thermogravimetric Analyzer ◽  
Degradation Temperature ◽  
Reinforcement Content ◽  
Biocomposite Films

The objectives of this research were to prepare self-reinforcement biocomposites films from sisal cellulose by solvent casting using NaOH complex solution and to investigate the effect of reinforcement content (i.e., 0, 5, 10, 15, and 20 wt %) in various forms, i.e., sisal microcrystalline cellulose (MCC), commercial MCC, and short sisal fiber, respectively. The sisal MCC was extracted from sisal fiber by means of delignification, bleaching, and acid hydrolysis, respectively. The obtained MCC powder observed by scanning electron microscope (SEM) appeared as short fiber shape with smooth surface having diameter of approximately 10 μm, whereas its length was varied between 67-150 μm. The tensile strength and Young’s modulus of the composite films reinforced with 15 wt % of sisal MCC reached up to 5.16 MPa and 375.25 MPa, respectively. The degradation temperature investigated by thermogravimetric analyzer (TGA) and water absorption values were significantly improved with increasing of reinforcement loading.

STUDIES ON BIODEGRADATION OF CELLULOSE NANOFIBRIL REINFORCED STARCH/PVA BIOCOMPOSITE FILMS USING AEROBIC COMPOST ENVIRONMENT

2011 ◽  
Vol 10 (04n05) ◽  
pp. 1143-1146
Author(s):  
SONAKSHI MAITI ◽  
DEBARATI MITRA ◽  
DIPA RAY
Keyword(s):  
Cellulose Nanofibrils ◽  
X Ray Diffraction ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
Xrd Study ◽  
Biocomposite Films ◽  
Structures And Properties ◽  
Significant Difference ◽  
Increasing Trend ◽  
Solution Casting Method

Starch/PVA biocomposite films reinforced with cellulose nanofibrils were prepared by solution casting method incorporating glycerol as a plasticizer. These biocomposite films along with unreinforced films were subjected to biodegradation in an aerobic compost pit. The extents of biodegradation of these films were studied in terms of persentage weight loss. The corresponding changes in the structures and properties of these biocomposites were investigated using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) study and Differential Scanning Calorimetry (DSC). The presence of fillers influenced the arrangement of the starch and PVA molecules in the film compared to that in the unreinforced film. A significant difference was observed in the nature of biodegradation of unreinforced and the reinforced films. The glass transition temperature, as observed from DSC, showed a decreasing trend, while the melting temperature showed an increasing trend after biodegradation. SEM micrographs revealed that the starch portions were consumed at a faster rate compared to polyvinyl alcohol, which was confirmed from XRD graphs also.

Effectiveness assessment of TiO2-Al2O3 nano-mixture as a filler material for improvement of packaging performance of PLA nanocomposite films

2020 ◽  
Vol 40 (10) ◽  
pp. 848-858
Author(s):  
Fatima Zohra Yakdoumi ◽  
Assia Siham Hadj-Hamou
Keyword(s):  
Polylactic Acid ◽  
Nanocomposite Film ◽  
Food Packaging ◽  
Antimicrobial Properties ◽  
Young Modulus ◽  
Nanocomposite Films ◽  
Vapor Permeability ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Vis Spectroscopy

AbstractThe main objective of this study was to assess the effectiveness of TiO2-Al2O3 nano-mixture used as filler in improving packaging films performance. Polylactic acid/titanium dioxide (PLA/TiO2), polylactic acid/alumina (PLA/Al2O3) and polylactic acid/TiO2-Al2O3 (PLA/TiO2-Al2O3) nanocomposite films were successfully prepared via melt mixing process and thoroughly characterized by FTIR spectroscopy, X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties such as heat resistant, barrier, mechanical and antimicrobial properties, required for food packaging have also been investigated. As compared to the neat PLA film, the developed PLA nanocomposites have displayed superior properties particularly the PLA/ TiO2-Al2O3 nanocomposite film. This resulted material has showed a 22 °C increase in its thermal stability versus 14 and 2 °C in the cases of PLA/TiO2 and PLA/Al2O3 respectively, and a 54% reduction of its water vapor permeability in comparison with 47% for PLA/TiO2 and 39% for PLA/Al2O3. In addition, the PLA/TiO2-Al2O3 had a significant enhancement of its mechanical properties. Its Young modulus increased by 102% unlike 23.60% for the PLA/TiO2 and 44.66% for the PLA/Al2O3. It was also noticed that this nanocomposite film demonstrated stronger antibacterial activity than the two others. The bacterial growth inhibition effect of TiO2-Al2O3 nano-mixture against Pseudomonas aeruginosa and Escherichia coli bacteria was more effective than that of its two constituents.

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

2016 ◽  
Vol 29 (9) ◽  
pp. 1097-1109 ◽  
Author(s):  
Shuai Lei ◽  
Shuai Wu ◽  
Aijun Gao ◽  
Weiyu Cao ◽  
Changqing Li ◽  
...  
Keyword(s):  
Nitrogen Atmosphere ◽  
Structural Defects ◽  
Scanning Calorimetry ◽  
Thermogravimetric Analyzer ◽  
Graphitization Degree ◽  
Temperature Ramp ◽  
Graphite Structure ◽  
Chemical Groups ◽  
Graphite Sheets

Three types of polyacrylonitrile (PAN) were considered in order to investigate the effect of molecular composition and configuration on the formation of conjugated structures during stabilization and the conversion of that to pseudo-graphite sheets after carbonization. The stabilization process was performed in an inert or oxidative atmosphere with a temperature ramp from 180°Cto 280°C. The thermal behavior was studied by differential scanning calorimetry, and the change of chemical groups and conjugated structures was detected by in situ measurement of infrared (Fourier transform infrared) and ultraviolet–visible spectroscopy, respectively. The carbonization process of the stabilized samples was performed using a thermogravimetric analyzer under nitrogen atmosphere in the temperature range of 150°C–1200°C, and Raman spectra were applied to study the pseudo-graphite sheets of the residuals. It is suggested that the introduction of comonomer or the improvement of the isotactic regularity of the polymer chain are helpful to promote the stabilization reactions and accelerate the formation of conjugated structures rather than the extent of conjugation during stabilization in nitrogen. Moreover, they are also beneficial to obtain higher degree of graphitization and larger size of the pseudo-graphite sheets with less structural defects after carbonization. While stabilization is performed in air, atactic PAN copolymer has the highest extent of stabilization among these three PAN samples, but they are extremely close. PAN samples with comonomer or higher isotacticity still show a little advantage in the formation speed of the conjugated structures. After carbonization, PAN with higher isotacticity has the highest carbon yield and graphitization degree and the largest size of pseudo-graphite sheets with least structural defects. In addition, the presence of oxygen during stabilization is contributory to increase the extent of stabilization and generate some bigger conjugated structures, which leads to obtain higher graphitization degree and larger size of pseudo-graphite sheets, but it also brings more structural defects.

Thermal Behaviour of Candesartan Active substance and in pharmaceutical compounds

2017 ◽  
Vol 68 (8) ◽  
pp. 1895-1902
Author(s):  
Ioana Cristina Tita ◽  
Eleonora Marian ◽  
Bogdan Tita ◽  
Claudia Crina Toma ◽  
Laura Vicas
Keyword(s):  
Thermal Behaviour ◽  
Active Substance ◽  
Pharmaceutical Research ◽  
Pharmaceutical Product ◽  
Nitrogen Atmosphere ◽  
Pure Substance ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ft Ir

Thermal analysis is one of the most frequently used instrumental techniques in the pharmaceutical research, for the thermal characterization of different materials from solids to semi-solids, which are of pharmaceutical relevance. In this paper, simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) were used for characterization of the thermal behaviour of candesartan cilexetil � active substance (C-AS) under dynamic nitrogen atmosphere and nonisothermal conditions, in comparison with pharmaceutical product containing the corresponding active substance. It was observed that the commercial samples showed a different thermal profile than the standard sample, caused by the presence of excipients in the pharmaceutical product and to possible interaction of these with the active substance. The Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) were used as complementary techniques adequately implement and assist in interpretation of the thermal results. The main conclusion of this comparative study was that the TG/DTG and DSC curves, together with the FT-IR spectra, respectively X-ray difractograms constitute believe data for the discrimination between the pure substance and pharmaceutical forms.

scholarly journals Torrefaction Thermogravimetric Analysis and Kinetics of Sorghum Distilled Residue for Sustainable Fuel Production

2021 ◽  
Vol 13 (8) ◽  
pp. 4246
Author(s):  
Shih-Wei Yen ◽  
Wei-Hsin Chen ◽  
Jo-Shu Chang ◽  
Chun-Fong Eng ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Pso Algorithm ◽  
Nitrogen Atmosphere ◽  
Computational Method ◽  
Weight Changes ◽  
Design And Optimization ◽  
Thermogravimetric Analyzer ◽  
Model Free ◽  
Different Temperatures ◽  
Kinetics Of

This study investigated the kinetics of isothermal torrefaction of sorghum distilled residue (SDR), the main byproduct of the sorghum liquor-making process. The samples chosen were torrefied isothermally at five different temperatures under a nitrogen atmosphere in a thermogravimetric analyzer. Afterward, two different kinetic methods, the traditional model-free approach, and a two-step parallel reaction (TPR) kinetic model, were used to obtain the torrefaction kinetics of SDR. With the acquired 92–97% fit quality, which is the degree of similarity between calculated and real torrefaction curves, the traditional method approached using the Arrhenius equation showed a poor ability on kinetics prediction, whereas the TPR kinetic model optimized by the particle swarm optimization (PSO) algorithm showed that all the fit qualities are as high as 99%. The results suggest that PSO can simulate the actual torrefaction kinetics more accurately than the traditional kinetics approach. Moreover, the PSO method can be further employed for simulating the weight changes of reaction intermediates throughout the process. This computational method could be used as a powerful tool for industrial design and optimization in the biochar manufacturing process.

scholarly journals A Characteristic Study of Polylactic Acid/Organic Modified Montmorillonite (PLA/OMMT) Nanocomposite Materials after Hydrolyzing

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 376
Author(s):  
Su-Mei Huang ◽  
Jiunn-Jer Hwang ◽  
Hsin-Jiant Liu ◽  
An-Miao Zheng
Keyword(s):  
Thermal Stability ◽  
Polylactic Acid ◽  
Decomposition Temperature ◽  
Material Strength ◽  
Scanning Calorimetry ◽  
Hydrolysis Process ◽  
Twin Screw ◽  
Thermal Pressing ◽  
Organophilic Clay ◽  
Mmt Clay

In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction (XRD) revealed that the organic modified-MMT(OMMT) was distributed successfully in the PLA matrix. After thermal pressing, the thermal stability of the mixed composites was measured by a TGA. The mixed composites were also blended with OMMT by a co-rotating twin screw extruder palletizing system, and then injected for the ASTM-D638 standard specimen by an injection machine for measuring the material strength by MTS. The experimental results showed that the mixture of organophilic clay and PLA would enhance the thermal stability. In the PLA mixed with 3 wt% OMMT nanocomposite, the TGA maximum decomposition temperature (Tmax) rose from 336.84 °C to 339.08 °C. In the PLA mixed with 5 wt% OMMT nanocomposite, the loss of temperature rose from 325.14 °C to 326.48 °C. In addition, the elongation rate increased from 4.46% to 10.19% with the maximum loading of 58 MPa. After the vibrating hydrolysis process, the PLA/OMMT nanocomposite was degraded through the measurement of differential scanning calorimetry (DSC) and its Tg, Tc, and Tm1 declined.

scholarly journals Effect of Glycero-(9,10-trioxolane)-trialeate on the Physicochemical Properties of Non-Woven Polylactic Acid Fiber Materials

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2517
Author(s):  
Anatoliy Olkhov ◽  
Olga Alexeeva ◽  
Marina Konstantinova ◽  
Vyacheslav Podmasterev ◽  
Polina Tyubaeva ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Polylactic Acid ◽  
Specific Surface Area ◽  
Water Sorption ◽  
Fiber Surface ◽  
High Water ◽  
Scanning Calorimetry ◽  
Fiber Mats ◽  
Fiber Materials

Biocompatible glycero (9,10-trioxolane) trioleate (ozonide of oleic acid triglyceride, OTOA) was incorporated into polylactic acid (PLA) fibers by electrospinning and nonwoven PLA mats with 1%, 3% and 5% OTOA content. The morphological, mechanical, thermal and water sorption properties of electrospun PLA mats after the addition of OTOA were studied. A morphological analysis showed that the addition of OTOA increased the average fiber diameter and induced the formation of pores on the fiber surface, leading to an increase in the specific surface area for OTOA-modified PLA fibrous mats. PLA fiber mats with 3% OTOA content were characterized by a highly porous surface morphology, an increased specific surface area and high-water sorption. Differential scanning calorimetry (DSC) was used to analyze the thermal properties of the fibrous PLA mats. The glass transition temperatures of the fibers from the PLA–OTOA composites decreased as the OTOA content increased, which was attributed to the plasticizing effect of OTOA. DSC results showed that OTOA aided the PLA amorphization process, thus reducing the crystallinity of the obtained nonwoven PLA–OTOA materials. An analysis of the mechanical properties showed that the tensile strength of electrospun PLA mats was improved by the addition of OTOA. Additionally, fibrous PLA mats with 3% OTOA content showed increased elasticity compared to the pristine PLA material. The obtained porous PLA electrospun fibers with the optimal 3% OTOA content have the potential for various biomedical applications such as drug delivery and in tissue engineering.

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