Effect of Laser Surface Modification on the Crystallinity of Poly(L-Lactic Acid)

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Anubha Bhatla ◽  
Y. Lawrence Yao
Keyword(s):  
Lactic Acid ◽  
Polymer Surface ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
Laser Surface Modification ◽  
Third Harmonic ◽  
X Ray ◽  
Annealing Conditions ◽  
Kinetics Of

Crystallinity of semicrystalline polymers such as aliphatic homopolymer poly(L-lactic acid) (PLLA) affects their degradation and physical properties. In this paper, the effects of laser irradiation using the third harmonic of a Nd:YAG laser on the crystallinity, long-range order, and short-range conformations at the surface of PLLA films are investigated. The factors affecting the transformation are also studied. Detailed characterization of the effect of laser treatment is accomplished using microscopy, X-ray diffraction, and infrared spectroscopy. The cooling rates in the process and the spatial and temporal temperature profiles are numerically examined. The simulation results in conjunction with melting and crystallization kinetics of PLLA are used to understand the effect on sample crystallinity. The effects of laser fluence and annealing conditions on the crystallinity of the processed films are examined. Since degradation profiles depend on crystallinity, laser processing can potentially be used to achieve a modified spatially controlled polymer surface with promising applications such as controlled drug delivery.

Simulations of High-Strain Electrostrictive Chlorinated Terpolymers

2003 ◽  
Vol 785 ◽  
Author(s):  
George J. Kavarnos ◽  
Thomas Ramotowski
Keyword(s):  
Vinylidene Fluoride ◽  
High Strain ◽  
Polymer Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lamellar Structures ◽  
Annealing Conditions ◽  
Poly Vinylidene Fluoride ◽  
Electromechanical Responses ◽  
Kinetics Of

ABSTRACTChlorinated poly(vinylidene fluoride/trifluoroethylene) terpolymers are remarkable examples of high strain electrostrictive materials. These polymers are synthesized by copolymerizing vinylidene fluoride and trifluoroethylene with small levels of a third chlorinated monomer. The electromechanical responses of these materials are believed to originate from the chlorine atom, which, by its presence in the polymer chains and by virtue of its large van der Waals radius, destroys the long-range crystalline polar macro-domains and transforms the polymer from a normal to a high-strain relaxor ferroelectric. To exploit the strain properties of the terpolymer, it is desirable to understand the structural implications resulting from the presence of the chlorinated monomer. To this end, computations have been performed on model superlattices of terpolymers using quantum-mechanical based force fields. The focus has been on determining the energetics and kinetics of crystallization of the various polymorphs that have been identified by x-ray diffraction and fourier transform infrared spectroscopy. The chlorinated monomer is shown to act as a defect that can be incorporated into the lamellar structures of annealed terpolymer without a high cost in energy. The degree of incorporation of the chlorinated monomer into the crystal lattice is controlled by annealing conditions and ultimately determines the ferroelectric behavior of the terpolymers.

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.

Synthesis and Characterization of Novel Inorganic Microporous Beryllophosphates

1992 ◽  
Vol 57 (4) ◽  
pp. 794-798 ◽  
Author(s):  
Long Yu ◽  
Wenqin Pang
Keyword(s):  
Ion Exchange ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
X Ray ◽  
Earth Cation ◽  
Diffraction Patterns ◽  
Unique Framework ◽  
Exchange Properties

Five new types of microporous beryllophosphates were hydrothermally synthesized using BeO-P2O5-R-MCl (or MCl2)-H2O, R being cyclohexylamine (CHA), pyrrolidine, 1-butylamine or triethylamine, M alkali or alkali earth cation. X-Ray diffraction patterns (XRD), infrared (IR), TG-DT and elemental analysis show that the crystalline beryllophosphates have novel, unique framework structures, composed from basic units of tetrahedral PO4 and BeO4. These materials exhibit zeolite-like adsorption and ion-exchange properties. Factors affecting the product crystallization (as e.g. pH), type of cation and composition of reaction mixture are discussed.

Microstructural Characterization of Ba2YCu3O7 Films Produced by Co-Evaporation

1987 ◽  
Vol 99 ◽  
Author(s):  
G. J. Fisanick ◽  
P. Mankeewicht ◽  
W. Skocpolt ◽  
R. E. Howardt ◽  
A. Dayem ◽  
...  
Keyword(s):  
Plane Surface ◽  
Depth Profiling ◽  
Microstructural Characterization ◽  
Areal Density ◽  
Oxygen Stoichiometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Conditions ◽  
Auger Microscopy

ABSTRACTBa2YCu3O7 films produced by co-evaporation of BaF2, Cu and Y onto <100> S1TiO3 substrates in an O2 ambient followed by post-annealing were analyzed using RBS, X-ray diffraction and Auger microscopy. These films exhibit Tc's (R=0) of =90K and a best Jc of > 1.0×106 A/cm2 at 81K for a =2500A thick film. RBS and Auger depth profiling limit the level of F present in the post-annealed films to <5 at. %, although F is evident in the as-deposited material. RBS channeling experiments yield a Xmin=31%, demonstrating the epitaxial quality of the films. X-ray diffraction shows that the films are predominantly oriented with c-axis perpendicular to the substrate, with narrow mosaic spread in-plane. A small portion of the film is in the form of needles oriented with a-axis perpendicular to the substrate, whose areal density is dependent on annealing conditions and local film stoichiometry. Scanning Auger microscopy confirms that the needles and c-axis plateaus have the same metal and oxygen stoichiometry. Also present in the film are insulating balls which appear to nucleate terraces in the c-axis perpendicular structure. Scanning Auger shows that these features are also close to the metals stoichiometry, but are C rich compared to the needles. The plateaus are covered with =11 times more C than the needles, indicating that the basal plane surface is highly reactive. Auger depth profiling and RBS show little evidence for interdiffusion.

Characterization of Nanocrystalline γ–Fe2O3Prepared by Wet Chemical Method

1999 ◽  
Vol 14 (4) ◽  
pp. 1570-1575 ◽  
Author(s):  
G. Ennas ◽  
G. Marongiu ◽  
A. Musinu ◽  
A. Falqui ◽  
P. Ballirano ◽  
...  
Keyword(s):  
Isothermal Treatment ◽  
X Ray Diffraction ◽  
Ferrous Chloride ◽  
Scanning Calorimetry ◽  
Direct Transformation ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Kinetics Of

Homogeneous maghemite (γ–Fe2O3) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (α–Fe2O3), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 °C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.

scholarly journals Synthesis and Characterization of Erythromycin Loaded PLGA and PCL Microspheres: Antimicrobial Application

2021 ◽  
Author(s):  
Lamia Bennabi ◽  
Ilham Abedelemalek ◽  
Abedelkader Ammari ◽  
Khaldia Sediri ◽  
Fatima Bennabi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Glycolic Acid ◽  
Release Kinetics ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complementary Effect ◽  
Kinetics Of ◽  
Scanning Electron

Abstract We presents in this work the preparation of several formulations, based on biocompatible biodegradable polymers: polycaprolactone (PCL) and poly(lactic-co-glycolic) acid (PLGA) loaded with Erythromycin (ERYT) antibiotic. These biocompatible materials were used to prepare microspheres with and without immobilized ERYT via simple evaporation method by simple emulsion. The particle size was determined by scanning electron microscopy and the absence of the interaction with ERYT was confirmed via X-ray diffraction and infrared spectroscopy. The release kinetics of ERYT were studied and then, ERYT loaded PCL and PLGA blends microspheres were used for the inhibition of gram-positive S. aureus strain. The microbial activity was carried-out by Agar diffusion disc method. The results show that PCL/PLGA blend and PCL alone inhibited the strain by ERYT present in kinetic aliquots with the complementary effect of the polymers. A numerical model was proposed for modeling the kinetics reported in our study.

scholarly journals Karakterisasi Nanokomposit Poly(Lactic Acid)-Spent Bleaching Earth Regenerasi Termodifikasi

KOVALEN ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 90-98
Author(s):  
Tika Paramitha ◽  
Johnner P. Sitompul
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Bleaching Earth ◽  
Renewable Resource ◽  
Urea Solution ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Universal Testing

Development of renewable resource-based polymers attracts attention to solve environmental problems due to the build up of polymer (plastic). Poly(lactic acid) (PLA) is one of the most widely used polymers which have good biodegradability and processability. The addition of fillers to the PLA matrix aims to improve the characteristics of the PLA, such as mechanical properties of nanocomposites of PLA. Thus, PLA can be use as substitution of fossil fuel-based polymer. Spent Bleaching Earth (SBE) can be used as a filler after regeneration process. SBE was extracted and oxidized to take its oil content. Then, SBE was modified with urea solution to increase the interlayer distance. In this study, structure of nanocomposites was characterized using X-Ray Diffraction and mechanical properties of nanocomposites were characterized using Universal Testing Machines. X-Ray Diffraction characterization results show that PLA-SBE nanocomposite and PLA-modified regenerated SBE nanocomposites do not form new peaks, so SBE and modified regenerated SBE is intercalated and partially exfoliated in the PLA matrix. The degree of intercalation/exfoliation is indicated by the results of characterization of mechanical properties. The mechanical properties of PLA-SBE nanocomposite are lower than neat PLA, whereas the mechanical properties of PLA-modified regenerated SBE nanocomposites are higher than neat PLA. The best mechanical properties of nanocomposites were obtained for PLA-5% modified regenerated SBE, with elongation and tensile strength, 3.26%, and 42.22 MPa, respectively. Keywords: nanocomposites, poly(lactic acid), regeneration, spent bleaching earth

Characterization of Cup Earing in Tin Mill Product by X-Ray Diffraction

1999 ◽  
Vol 5 (S2) ◽  
pp. 880-881
Author(s):  
K. C Liao ◽  
W.C. Swartz
Keyword(s):  
Processing Parameters ◽  
Continuous Annealing ◽  
X Ray Diffraction ◽  
Normal Anisotropy ◽  
Mill Product ◽  
Crystalline Materials ◽  
X Ray ◽  
Annealing Conditions ◽  
Xrd Techniques

X-ray diffraction (XRD) techniques can readily be utilized for the characterization of textures in crystalline materials. The advantages of XRD techniques are: 1) the test is nondestructive, 2) samples can easily be prepared, and 3) data can be collected and analyzed quickly.Three low-C steel tin mill coils were manufactured during a mill trial which was conducted to optimize the processing parameters necessary for the production of material with low cup earing behavior. The processing parameters evaluated included hot mill conditions (roughing, finishing and coiling temperatures), cold rolling conditions (during first and second cold reduction), and continuous annealing conditions (line speed and strip temperature). Samples A, B, and C were secured from the coil center-width position of each coil, respectively, and were analyzed via XRD.Properties such as normal anisotropy (r bar) and planar anisotropy (Δ r), have been correlated with an X-ray Intensity Ratio (XIR) at the Technical Center of National Steel.

Preparation and Characterization of Poly(lactic acid)/Difatty Acyl Urea/Modified Clay Nanocomposite

2011 ◽  
Vol 364 ◽  
pp. 81-85 ◽  
Author(s):  
Emad A. Jaffar Al-Mulla
Keyword(s):  
Lactic Acid ◽  
Casting Process ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Clay Particles ◽  
X Ray ◽  
Modified Clay ◽  
Clay Modification ◽  
Transmission Electron

In this study, difatty acyl urea (DFAU), synthesized from palm oil, and natural clay (sodium montmorillonite) were used to prepare organoclay (OMMT). The clay modification was carried out by stirring the clay particles in an aqueous solution of DFAU at which the clay layer thickness increased from 1.25 to 2.82. This OMMT was then used for nanocomposite production to improve the property balance of poly (lactic acid) (PLA) by solution casting process. The nanocomposite was characterized using various apparatuses. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results confirmed the production of nanocomposite. PLA modified clay nanocomposite shows higher thermal stability and significant improvement of mechanical properties in comparison with pure PLA. The use of DFAU as a modifier will reduce the dependence on petroleum-based surfactant. In addition to its applications such as films and textile fibers, this nanocomposite represents a good candidate to produce disposable packaging because they have good mechanical, thermal properties, fabricability and processability.

scholarly journals Characterization of the expanded austenite developed on AISI 316 LM steel by plasma nitriding

2017 ◽  
Vol 53 (1) ◽  
pp. 47-52 ◽  
Author(s):  
M. Keddam ◽  
T. Thiriet ◽  
G. Marcos ◽  
T. Czerwiec
Keyword(s):  
Optical Emission Spectroscopy ◽  
Plasma Nitriding ◽  
Optical Emission ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Expanded Austenite ◽  
Aisi 316 ◽  
Kinetics Of

AISI 316 LM samples were plasma nitrided at a temperature of 380?C for different times between 0.5 and 8 h in a 85%N2- 15%H2 gas mixture. Different experimental techniques such as: optical microscopy (OM), X- ray diffraction (XRD ) and glow discharge optical emission spectroscopy (GDOES) were used to characterize the expanded austenite layer formed at the surface of AISI 316 LM stainless steel. The microscopical observations revealed the presence of the expanded austenite with a mean layer thickness between 1.90 and 4.31 ?m. The growth kinetics of expanded austenite was also investigated. In addition, both the compressive stresses in the expanded austenite layer and the compositional strains were estimated by means of a simple mechanical model based on the XRD results.

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