scholarly journals Investigation of the Influence of PLA Molecular and Supramolecular Structure on the Kinetics of Thermal-Supported Hydrolytic Degradation of Wet Spinning Fibres

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2111
Author(s):  
Małgorzata Giełdowska ◽  
Michał Puchalski ◽  
Grzegorz Szparaga ◽  
Izabella Krucińska
Keyword(s):  
Supramolecular Structure ◽  
Degradation Kinetics ◽  
Amorphous Material ◽  
Hydrolytic Degradation ◽  
Crystalline Material ◽  
Wet Spinning ◽  
Initial Structure ◽  
Degradation Temperature ◽  
Kinetics Of ◽  
Mass Erosion

In this study, differences in the kinetics of the thermal-supported hydrolytic degradation of polylactide (PLA) wet spinning fibres due to material variance in the initial molecular and supramolecular structure were analysed. The investigation was carried out at the microstructural and molecular levels by using readily available methods such as scanning electron microscopy, mass erosion measurement and estimation of intrinsic viscosity. The results show a varying degree of influence of the initial structure on the degradation rate of the studied PLA fibres. The experiment shows that hydrolytic degradation at a temperature close to the cold crystallization temperature is, on a macroscopic level, definitely more rapid for the amorphous material, while on a molecular scale it is similar to a semi-crystalline material. Furthermore, for the adopted degradation temperature of 90 °C, a marginal influence of the pH of the degradation medium on the degradation kinetics was also demonstrated.

scholarly journals Investigation of the Influence of PLA Molecular and Supramolecular Structure on the Kinetics of Thermal-Supported Hydrolytic Degradation of Wet Spinning Fibres

2020 ◽  
Author(s):  
Małgorzata Giełdowska ◽  
Michał Puchalski ◽  
Grzegorz Szparaga ◽  
Izabella Krucinska
Keyword(s):  
Supramolecular Structure ◽  
Degradation Kinetics ◽  
Amorphous Material ◽  
Hydrolytic Degradation ◽  
Wet Spinning ◽  
Poly Lactic Acid ◽  
Initial Structure ◽  
Degradation Temperature ◽  
Influence Of Ph ◽  
Kinetics Of

In this study, differences in the kinetics of thermal-supported hydrolytic degradation of poly(lactic acid) (PLA) sample wet spinning fibres due to material variance in the initial molecular and supramolecular structure were analysed. The investigation was carried out at the microstructural and molecular levels by using readily available methods such as scanning electron microscopy, mass erosion measurement and estimation of intrinsic viscosity. The results show a varying degree of influence of the initial structure on the degradation rate of studied PLA fibres. The experiment shows that hydrolytic degradation at a temperature close to the cold crystallization temperature on a macroscopic level is definitely more rapid for the amorphous material, while on a molecular scale it is similar to a semi-crystalline material. Further, for the adopted degradation temperature of 90 °C, a marginal influence of pH of the degradation medium on the degradation kinetics was also demonstrated

Computer-Aided 4D Modeling of Hydrolytic Degradation in Micropatterned Bioresorbable Membranes

2013 ◽  
Vol 7 (2) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
Michelle Marchany ◽  
Joseph A. Gardella ◽  
Bahattin Koc
Keyword(s):  
Degradation Kinetics ◽  
Morphological Changes ◽  
Dynamic Geometry ◽  
Hydrolytic Degradation ◽  
Controlled Drug Release ◽  
Polymeric Membranes ◽  
Surface Erosion ◽  
Computer Aided ◽  
Kinetics Of

Real-time degradation studies of bioresorbable polymers can take weeks, months, and even years to conduct. For this reason, developing and validating mathematical models that describe and predict degradation can provide a means to accelerate the development of materials and devices for controlled drug release. This study aims to develop and experimentally validate a computer-aided model that simulates the hydrolytic degradation kinetics of bioresorbable polymeric micropatterned membranes for tissue engineering applications. Specifically, the model applies to circumstances that are conducive for the polymer to undergo surface erosion. The developed model provides a simulation tool enabling the prediction and visualization of the dynamic geometry of the degrading membrane. In order to validate the model, micropatterned polymeric membranes were hydrolytically degraded in vitro and the morphological changes were analyzed using optical microscopy. The model is then extended to predict spatiotemporal degradation kinetics of variational micropatterned architectures.

Thermal Degradation Kinetics of Polyurethane/polybenzoxazine Alloys

2011 ◽  
Vol 214 ◽  
pp. 439-443 ◽  
Author(s):  
Sunan Tiptipakorn ◽  
Sarawut Rimdusit ◽  
Phiriyathorn Suwanmala ◽  
Kasinee Hemvichian
Keyword(s):  
Thermal Degradation ◽  
Heating Rate ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Thermogravimetric Analyzer ◽  
First Derivative ◽  
Degradation Temperature ◽  
Kissinger Model ◽  
Ozawa Model ◽  
Kinetics Of

Recently, the alloys of polyurethane (PU)/polybenzoxazine (PBA-a) have been studied due to many interesting properties; however, the thermal degradation kinetics of the system has not been mentioned before. In this study, the degradation temperatures of the obtained alloys were determined using Thermogravimetric Analyzer (TGA) with various heating rate of 10, 20, 25oC/min. The polyurethane /polybenzoxazine alloys at the weight ratios of 30/70 were prepared for determination due to its highest degradation temperature. The first derivative curves of the thermograms (DTG) were deconvoluted with Peak-fit program. The results reveal three main sub-stages of degradation. According to Arrhenius Eq., the activation energies (Ea) of each degradation sub-stage were determined using Kissinger model and Fynn-Wall Ozawa model.

scholarly journals Degradation kinetics of oligo(ε-caprolactone) ultrathin films: Influence of crystallinity

MRS Advances ◽  
2021 ◽  
Author(s):  
Shivam Saretia ◽  
Rainhard Machatschek ◽  
Andreas Lendlein
Keyword(s):  
Ultrathin Films ◽  
Degradation Kinetics ◽  
Hydrolytic Degradation ◽  
Solid Surfaces ◽  
Crystalline Morphology ◽  
Melting Temperatures ◽  
Complete Melting ◽  
Air Water Interface ◽  
Crystalline Films ◽  
Kinetics Of

Abstract The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(ε-caprolactone) (OCL) are prepared at the air–water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH ~ 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices. Graphic abstract

Hydrolytic degradation kinetics of bisphenol E cyanate ester resin and composite

2018 ◽  
Vol 151 ◽  
pp. 1-11 ◽  
Author(s):  
James A. Throckmorton ◽  
Greg Feldman ◽  
Giuseppe R. Palmese ◽  
Andrew J. Guenthner ◽  
Kevin R. Lamison ◽  
...  
Keyword(s):  
Degradation Kinetics ◽  
Hydrolytic Degradation ◽  
Cyanate Ester ◽  
Cyanate Ester Resin ◽  
Kinetics Of

The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 277-295 ◽  
Author(s):  
A Silver ◽  
M Murray
Keyword(s):  
Amino Acids ◽  
Competitive Inhibition ◽  
Amorphous Material ◽  
Peptide Bond ◽  
Initial Reaction ◽  
Reaction Products ◽  
Coagulation Mechanism ◽  
Kinetics Of ◽  
Kinetics Of Inhibition ◽  
Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

scholarly journals Degradation Kinetics of Humic acid in Aqueous Solution by Ozonation Treatment under Different Parameter Conditions

2020 ◽  
Vol 596 ◽  
pp. 012010
Author(s):  
Zafirah Mahyun ◽  
Noor Fazliani Shoparwe ◽  
Ahmad Zuhairi Abdullah ◽  
Abdul Latif Ahmad ◽  
Mardawani Mohamad ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Humic Acid ◽  
Degradation Kinetics ◽  
Kinetics Of

scholarly journals Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1597
Author(s):  
Iman Jafari ◽  
Mohamadreza Shakiba ◽  
Fatemeh Khosravi ◽  
Seeram Ramakrishna ◽  
Ehsan Abasi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Thermal Degradation ◽  
High Molecular Weight ◽  
Degradation Kinetics ◽  
Graphene Nanosheets ◽  
Thermal Degradation Kinetics ◽  
Graphene Nanocomposites ◽  
Kinetics Of ◽  
Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

Drying characteristics and lycopene degradation kinetics of tomato soup

2021 ◽  
pp. 100757
Author(s):  
Akshay Sonawane ◽  
O.P. Chauhan ◽  
Shubhankar D. Semwal ◽  
A.D. Semwal
Keyword(s):  
Degradation Kinetics ◽  
Drying Characteristics ◽  
Kinetics Of ◽  
Tomato Soup
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