Silk nanocrystals stabilized melt extruded poly (lactic acid) nanocomposite films: Effect of recycling on thermal degradation kinetics and optimization studies

2016 ◽  
Vol 643 ◽  
pp. 41-52 ◽  
Author(s):  
Melakuu Tesfaye ◽  
Rahul Patwa ◽  
Remya Kommadath ◽  
Prakash Kotecha ◽  
Vimal Katiyar
Keyword(s):  
Lactic Acid ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Nanocomposite Films ◽  
Thermal Degradation Kinetics ◽  
Poly Lactic Acid

Thermal degradation kinetics of Opuntia Ficus Indica flour and talc-filled poly (lactic acid) hybrid biocomposites by TGA analysis

2021 ◽  
pp. 002199832110082
Author(s):  
Azzeddine Gharsallah ◽  
Abdelheq Layachi ◽  
Ali Louaer ◽  
Hamid Satha
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Melt Processing ◽  
Thermal Degradation Kinetics ◽  
Poly Lactic Acid ◽  
Opuntia Ficus Indica ◽  
Model Free

This paper reports the effect of lignocellulosic flour and talc powder on the thermal degradation behavior of poly (lactic acid) (PLA) by thermogravimetric analysis (TGA). Lignocellulosic flour was obtained by grinding Opuntia Ficus Indica cladodes. PLA/talc/ Opuntia Ficus Indica flour (OFI-F) biocomposites were prepared by melt processing and characterized using Wide-angle X-ray scattering (WAXS) and Scanning Electron Microscope (SEM). The thermal degradation of neat PLA and its biocomposites can be identified quantitatively by solid-state kinetics models. Thermal degradation results on biocomposites compared to neat PLA show that talc particles at 10 wt % into the PLA matrix have a minor impact on the thermal stability of biocomposites. Loading OFI-F and Talc/OFI-F mixture into the PLA matrix results in a decrease in the maximum degradation temperature, which means that the biocomposites have lower thermal stability. The activation energies (Ea) calculated by the Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) model-free approaches and by model-fitting (Kissinger method and Coats-Redfern method) are in good agreement with one another. In addition, in this work, the degradation mechanism of biocomposites is proposed using Coats-Redfern and Criado methods.

scholarly journals Thermal Degradation Mechanism and Decomposition Kinetic Studies of Poly(Lactic Acid) and Its Copolymers with Poly(Hexylene Succinate)

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1365
Author(s):  
Iouliana Chrysafi ◽  
Nina Maria Ainali ◽  
Dimitrios N. Bikiaris
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bond ◽  
Lactic Acid ◽  
Thermal Degradation ◽  
Degradation Mechanism ◽  
Thermal Degradation Kinetics ◽  
Gas Chromatography Mass Spectrometry ◽  
Poly Lactic Acid ◽  
Bond Scission ◽  
New Material

Ιn this work, new block poly(lactic acid)-block-poly(hexylene succinate) (PLA-b-PHSu) copolymers, in different mass ratios of 95/05, 90/10 and 80/20 w/w, are synthesized and their thermal and mechanical behavior are studied. Thermal degradation and thermal stability of the samples were examined by Thermogravimetric Analysis (TGA), while thermal degradation kinetics was applied to better understand this process. The Friedman isoconversional method and the “model fitting method” revealed accurate results for the activation energy and the reaction mechanisms (nth order and autocatalysis). Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) was used to provide more details of the degradation process with PHSu’s mechanism being the β-hydrogen bond scission, while on PLA the intramolecular trans-esterification processes domains. PLA-b-PHSu copolymers decompose also through the β-hydrogen bond scission. The mechanical properties have also been tested to understand how PHSu affects PLA’s structure and to give more information about this new material. The tensile measurements gave remarkable results as the elongation at break increases as the content of PHSu increases as well. The study of the thermal and mechanical properties is crucial, to examine if the new material fulfills the requirements for further investigation for medical or other possible uses that might come up.

scholarly journals Thermal Stability and Decomposition Mechanism of PLA Nanocomposites with Kraft Lignin and Tannin

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2818
Author(s):  
Nina Maria Ainali ◽  
Evangelia Tarani ◽  
Alexandra Zamboulis ◽  
Klementina Pušnik Črešnar ◽  
Lidija Fras Zemljič ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Food Packaging ◽  
Degradation Kinetics ◽  
Kraft Lignin ◽  
Thermal Degradation Kinetics ◽  
Gas Chromatography Mass Spectrometry ◽  
Poly Lactic Acid ◽  
Pyrolysis Gas ◽  
Thermal Stability Of

Packaging applications cover approximately 40% of the total plastics production, whereas food packaging possesses a high proportion within this context. Due to several environmental concerns, petroleum-based polymers have been shifted to their biobased counterparts. Poly(lactic acid) (PLA) has been proved the most dynamic biobased candidate as a substitute of the conventional polymers. Despite its numerous merits, PLA exhibits some limitations, and thus reinforcing agents are commonly investigated as fillers to ameliorate several characteristics. In the present study, two series of PLA-based nanocomposites filled with biobased kraft-lignin (KL) and tannin (T) in different contents were prepared. A melt–extrusion method was pursued for nanocomposites preparation. The thermal stability of the prepared nanocomposites was examined by Thermogravimetric Analysis, while thermal degradation kinetics was applied to deepen this process. Pyrolysis–Gas Chromatography/Mass Spectrometry was employed to provide more details of the degradation process of PLA filled with the two polyphenolic fillers. It was found that the PLA/lignin nanocomposites show better thermostability than neat PLA, while tannin filler has a small catalytic effect that can reduce the thermal stability of PLA. The calculated Eα value of PLA-T nanocomposite was lower than that of PLA-KL resulting in a substantially higher decomposition rate constant, which accelerate the thermal degradation.

scholarly journals Crystalline Characteristics, Mechanical Properties, Thermal Degradation Kinetics and Hydration Behavior of Biodegradable Fibers Melt-Spun from Polyoxymethylene/Poly(l-lactic acid) Blends

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1753
Author(s):  
Jianhua Li ◽  
Yatao Wang ◽  
Xiaodong Wang ◽  
Dezhen Wu
Keyword(s):  
Lactic Acid ◽  
Thermal Degradation ◽  
Melt Spinning ◽  
Mechanical Performance ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Diameter Distribution ◽  
Crystalline Orientation ◽  
Bicomponent Fibers ◽  
Fractionation Analysis

A series of polyoxymethylene (POM)/poly(l-lactic acid) (PLLA) blends were prepared by melt extrusion, and their spinnability was confirmed by rheological characterizations, successive self-nucleation, and annealing thermal fractionation analysis. The bicomponent fibers were prepared by means of the melt-spinning and post-drawing technologies using the above-obtained blends, and their morphology, crystalline orientation characteristics, mechanical performance, hydration behavior, and thermal degradation kinetics were studied extensively. The bicomponent fibers exhibited a uniform diameter distribution and compact texture at the ultimate draw ratio. Although the presence of PLLA reduced the crystallinity of the POM domain in the bicomponent fibers, the post-drawing process promoted the crystalline orientation of lamellar folded-chain crystallites due to the stress-induced crystallization effect and enhanced the crystallinity of the POM domain accordingly. As a result, the bicomponent fibers achieved the relatively high tensile strength of 791 MPa. The bicomponent fibers exhibited a partial hydration capability in both acid and alkali media and therefore could meet the requirement for serving as a type of biodegradable fibers. The introduction of PLLA slightly reduced the thermo-oxidative aging property and thermal stability of the bicomponent fibers. Such a combination of two polymers shortened the thermal lifetime of the bicomponent fibers, which could facilitate their natural degradation for ecological and sustainable applications.

Thermal degradation kinetics and lifetime of high-density polyethylene/poly (l-lactic acid) blends

2015 ◽  
Vol 30 (6) ◽  
pp. 773-793 ◽  
Author(s):  
Gaurav Madhu ◽  
Dev K Mandal ◽  
Haripada Bhunia ◽  
Pramod K Bajpai
Keyword(s):  
Lactic Acid ◽  
Thermal Degradation ◽  
High Density Polyethylene ◽  
Degradation Kinetics ◽  
Estimation Method ◽  
Frequency Factor ◽  
High Density ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Model Free

In this work, a kinetic study on the thermal degradation of films prepared from high-density polyethylene (HDPE), poly(l-lactic acid) (PLLA) and their blends is presented. Activation energy ( Ea), order of reaction ( n) and frequency factor (ln ( A)) were studied through thermogravimetric analysis (TGA) over a temperature range of 25–600°C at four heating rates, that is, 5, 10, 15, and 20°C min−1. The TGA data were used to predict the thermal stability of the film samples, comparing the kinetic parameters obtained by three model-free isoconversional techniques and estimating the lifetime of the films. The value of Ea for neat HDPE was found to be much higher than that for PLLA, but for HDPE/PLLA blends, it was nearer to that of HDPE. An increase in Ea of 80/20 (HDPE/PLLA) blends was noticed with the addition of compatibilizer, maleic anhydride-grafted HDPE. Overall, the thermal kinetics of the polymer samples depends on fractions of their constituents, heating rates and calculation technique used. It was proved, through lifetime estimation method, that the lifetime of neat HDPE decreases by addition of PLLA. With increase in temperature, the lifetime of all samples decreased exponentially. Scanning electron microscopy studies verified that HDPE and PLLA interfaces became fairly compatible by adding the compatibilizer.

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