scholarly journals Stereocomplex Poly(Lactic Acid) Amphiphilic Conetwork Gel with Temperature and pH Dual Sensitivity

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1940 ◽  
Author(s):  
Jie Wu ◽  
Xiaoyu Shi ◽  
Zhidan Wang ◽  
Fei Song ◽  
Wenli Gao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Radical Copolymerization ◽  
Ph Sensitivity ◽  
Proton Nuclear Magnetic Resonance ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Free Radical Copolymerization ◽  
Good Thermal Stability ◽  
Ft Ir

A novel stereocomplex poly(lactic acid) amphiphilic conetwork gel with temperature and pH dual sensitivity was synthesized by ring-opening polymerization (ROP) and free radical copolymerization. The chemical structure and composition of hydrogel were characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) and X-ray diffraction (XRD). The temperature and pH sensitivity and good amphiphilicity of hydrogel were studied using digital photos, the swelling ratios and a scanning electron microscope (SEM). The thermal stability and mechanical properties of hydrogel were studied by differential scanning calorimeter (DSC) and dynamic viscoelastic spectrometer. The results indicated that the hydrogel has amphiphilicity, temperature and pH sensitivity, good thermal stability and mechanical strength.

Characterization of Electrospun Poly(Lactic Acid)/polyaniline Blend Nanofibers

2011 ◽  
Vol 332-334 ◽  
pp. 317-320 ◽  
Author(s):  
Hui Qin Zhang
Keyword(s):  
Lactic Acid ◽  
Composite Nanofibers ◽  
Weight Ratio ◽  
Electrospinning Process ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Ft Ir

In this study, composite nanofibers of polyaniline doped with dodecylbenzene sulfonic acid (PANI-DBSA) and Poly(lactic acid) (PLA) were prepared via an electrospinning process. The surface morphology, thermal properties and crystal structure of PLA/PANI-DBSA nanofibers are characterized using Fourier transform infrared spectroscopy (FT-IR), wide-angle x-ray diffraction (WAXD) and scanning electron microscopy (SEM). SEM images showed that the morphology and diameter of the nanofibers were affected by the weight ratio of blend solution.

scholarly journals Synthesis, Characterization and Copolymerization of N-(phenylamino)maleimide with MMA

2007 ◽  
Vol 4 (2) ◽  
pp. 265-271
Author(s):  
B. L. Hiran ◽  
S. N. Paliwal ◽  
Jyoti Choudhary ◽  
P. R. Choudhary
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Free Radical Copolymerization ◽  
H Nmr ◽  
Gel Permeation ◽  
Ft Ir ◽  
Thermal Stability Of

The free radical copolymerization of N-(phenylamino)maleimide (N-PAMI) was carried. The copolymerization with methyl methacrylate (MMA) was performed at 65°C with AIBN as the initiator in THF solvent. Resulting copolymer was characterized by density measurement, intrinsic viscosity, solubility, FT-IR &1H NMR spectroscopy. Effect of the solvent and time on copolymer yield was also investigated. The molecular weight of copolymer was determined by gel permeation chromatography (GPC). The thermal stability of copolymer was determined by Thermogravimetric analysis (TGA).

Blending and plasticising effects on the behaviour of poly(lactic acid)/poly(ε-caprolactone)

2018 ◽  
Vol 26 (5-6) ◽  
pp. 337-345 ◽  
Author(s):  
Nesrine Khitas ◽  
Kamira Aouachria ◽  
Mohamed Tahar Benaniba
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Triethyl Citrate ◽  
Acetyl Tributyl Citrate ◽  
The Degree Of Crystallinity

Polymer blending is one of the most convenient methods to be used to overcome the limitations of some single properties of polymers and to achieve the combinations required for specific applications. Another feasible common practice is the incorporation of additives of low molecular weight such as plasticisers to impart flexibility, improve toughness and lower the glass transition temperature ( Tg). This study focused on the effects of blending and plasticising on the crystallisation behaviour of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL). PCL with longer degradation time compared with other polymers was blended with PLA to overcome the limitation of its brittleness and poor thermal stability. Acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (TEC) were used as plasticiser in PLA/PCL blends. The rigid and plasticised blends at various ratios were analysed by differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The results revealed a slight increase in the degree of crystallinity and a significant increase in the Tg of PLA due to the addition of PCL. The addition of ATBC has promoted a decrease in thermal stability of the blends. The slight increase in the degree of crystallinity suggested that PCL acted as a nucleating agent. The citrate plasticisers were shown to lower the Tg and have much more enhanced the crystallisation of PLA. Moreover, the rigid and plasticised blends were shown to be partially miscible.

Bionanocomposites of Grass

2008 ◽  
Vol 47-50 ◽  
pp. 435-438 ◽  
Author(s):  
J.K. Pandey ◽  
Won Shik Chu ◽  
C.S. Kim ◽  
Caroline S. Lee ◽  
Sung Hoon Ahn
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Lactic Acid ◽  
Functional Group ◽  
Poly Lactic Acid ◽  
Moisture Resistance ◽  
Water Sensitivity ◽  
Group Variation ◽  
Ft Ir ◽  
Crystalline Nature

Cellulose nano whiskers (CNW) are recently known for their tremendous applicability in development of eco-friendly material for various applications. Present attempt was aimed to extract the nano crystals of cellulose from grass of Korea and fabricate the composites with poly (lactic acid) in presence of compatibilizer after modification. Functional group variation, thermal behavior, surface morphology, and crystallinity were monitored by FT-IR, TGA, SEM, and XRD respectively. The water sensitivity measurements were also carried out for study of moisture resistance of composites. It was found that CNW have lower thermal stability than alkali treated long fiber whereas the crystalline nature of composites decreased significantly. The effect of modification of whiskers on the mechanical properties was also discussed in which increase in modulus was observed.

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.

Formation of Hydroxycarbonate Apatite Layer on Poly(Lactic Acid) Composites in Simulated Body Fluid

2005 ◽  
Vol 284-286 ◽  
pp. 489-492 ◽  
Author(s):  
Hirotaka Maeda ◽  
Toshihiro Kasuga ◽  
Masayuki Nogami
Keyword(s):  
Lactic Acid ◽  
Simulated Body Fluid ◽  
Zeta Potential ◽  
Calcium Chloride ◽  
Composite Membrane ◽  
Body Fluid ◽  
Poly Lactic Acid ◽  
Zeta Potentials ◽  
Carbonate Ion ◽  
Ft Ir

Hydroxycarbonate apatite (HCA), which formed on a poly(lactic acid) (PLA) composite membrane containing vaterite or calcium chloride after soaking in simulated body fluid, was examined to clarify the importance of the ceramic phases in the composites. FT-IR spectra showed that the ratio of CO3/PO4 in the infrared adsorption bands of HCA formed on the PLA composite containing vaterite was much larger than that of HCA formed on the PLA composite containing calcium chloride. Substitution of carbonate ion in hydroxyapatite is believed to be strongly influenced by ceramic phases in the composites. The zeta potentials of HCA formed on the PLA composite containing vaterite or calcium chloride was -6 mV or -17 mV, respectively. The zeta potential may be influenced by the amount of carbonate ion in hydroxyapatite.

scholarly journals Preparations of Poly(lactic acid) Dispersions in Water for Coating Applications

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2767
Author(s):  
Giada Belletti ◽  
Sara Buoso ◽  
Lucia Ricci ◽  
Alejandro Guillem-Ortiz ◽  
Alejandro Aragón-Gutiérrez ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Sem Analysis ◽  
Water Phase ◽  
Poly Lactic Acid ◽  
Water Emulsion ◽  
Preparation Conditions ◽  
Ft Ir ◽  
Homogenization Methods ◽  
Oil In Water Emulsion

A green, effective methodology for the preparation of water-based dispersions of poly(lactic acid) (PLA) for coating purposes is herein presented. The procedure consists of two steps: in the first one, an oil-in-water emulsion is obtained by mixing a solution of PLA in ethyl acetate with a water phase containing surfactant and stabilizer. Different homogenization methods as well as oil/water phase ratio, surfactant and stabilizer combinations were screened. In the second step, the quantitative evaporation of the organic provides water dispersions of PLA that are stable, at least, over several weeks at room temperature or at 4 °C. Particle size was in the 200–500 nm range, depending on the preparation conditions, as confirmed by scanning electron microscope (SEM) analysis. PLA was found not to suffer significant molecular weight degradation by gel permeation chromatography (GPC) analysis. Furthermore, two selected formulations with glass transition temperature (Tg) of 51 °C and 34 °C were tested for the preparation of PLA films by drying in PTFE capsules. In both cases, continuous films that are homogeneous by Fourier-transform infrared spectroscopy (FT-IR) and SEM observation were obtained only when drying was performed above 60 °C. The formulation with lower Tg results in films which are more flexible and transparent.

Biophysical properties of electrospun chitosan-grafted poly(lactic acid) nanofibrous scaffolds loaded with chondroitin sulfate and silver nanoparticles

2021 ◽  
pp. 088532822110464
Author(s):  
Alexandre F Júnior ◽  
Charlene A Ribeiro ◽  
Maria E Leyva ◽  
Paulo S Marques ◽  
Carlos R J Soares ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Lactic Acid ◽  
Proton Nuclear Magnetic Resonance ◽  
Poly Lactic Acid ◽  
Fibroblast Cells ◽  
Biophysical Properties ◽  
Electrospinning Technique ◽  
Average Pore ◽  
H Nmr ◽  
Substitution Degree

The aim of this work was to study the biophysical properties of the chitosan-grafted poly(lactic acid) (CH-g-PLA) nanofibers loaded with silver nanoparticles (AgNPs) and chondroitin-4-sulfate (C4S). The electrospun CH-g-PLA:AgNP:C4S nanofibers were manufactured using the electrospinning technique. The microstructure of the CH-g-PLA:AgNP:C4S nanofibers was investigated by proton nuclear magnetic resonance (1H-NMR), scanning electron microscopy (SEM), UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR and 1H-NMR confirm the CH grafting successfully by PLA with a substitution degree of 33.4%. The SEM measurement results indicated apparently smooth nanofibers having a diameter range of 340 ± 18 nm with porosity of 89 ± 3.08% and an average pore area of 0.27 μm2. UV-Vis and XRD suggest that silver nanoparticles with the size distribution of 30 nm were successfully incorporated into the electrospun nanofibers. The water contact angle of 12.8 ± 2.7° reveals the hydrophilic nature of the CH-g-PLA:AgNP:C4S nanofibers has been improved by C4S. The electrospun CH-g-PLA:AgNP:C4S nanofibers are found to release ions Ag+ at a concentration level capable of rendering an antimicrobial efficacy. Gram-positive bacteria ( S.aureus) were more sensitive to CH-g-PLA:AgNP:C4S than Gram-negative bacteria ( E. coli). The electrospun CH-g-PLA:AgNP:C4S nanofibers exhibited no cytotoxicity to the L-929 fibroblast cells, suggesting cytocompatibility. Fluorescence microscopy demonstrated that C4S promotes the adhesion and proliferation of fibroblast cells onto electrospun CH-g-PLA:AgNP:C4S nanofibers.

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