A Study of the Kinetics of Polylactic Acid Crystallization by Image Processing

2009 ◽  
Vol 1242 ◽  
Author(s):  
F. Hernández-Sánchez ◽  
H. Carrillo-Escalante
Keyword(s):  
Polylactic Acid ◽  
Biomedical Application ◽  
Crystallization Kinetic ◽  
Amorphous State ◽  
Physical And Mechanical Properties ◽  
Video Camera ◽  
Optical Microscope ◽  
Degree Of Crystallinity ◽  
Crystallinity Degree ◽  
A New Technique

ABSTRACTThe polylactic acid (PLLA) is commonly used in the biomedical application. The physical and mechanical properties of PLLA depend on the molecular weight, crystallinity, and synthesis. In this work, we study the PLLA crystallization kinetics. One of the main attractive of these polymers is that its degree of crystallinity can easily be modified, from amorphous state to a high crystallinity degree. In this study a new technique is applied to follow the crystallization kinetic. An optical microscope with cross polarizers, warming plates and video camera were used. A series of images were obtained under isothermal conditions to observe the growth spherulite. Since an image is composed by pixels and each pixel has a value from 0 to 255, which represents gray intensity, being zero for black and 255 are white. Then, the pixels average versus time was plotting and from the plots crystallization kinetic and secondary crystallization are easily obtained.

scholarly journals Crystallization Behavior and Mechanical Properties of Poly(ε-caprolactone) Reinforced with Barium Sulfate Submicron Particles

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2368
Author(s):  
Hegoi Amestoy ◽  
Paul Diego ◽  
Emilio Meaurio ◽  
Jone Muñoz ◽  
Jose-Ramon Sarasua
Keyword(s):  
Barium Sulfate ◽  
Thermal Studies ◽  
Polarized Light ◽  
Optical Microscope ◽  
Submicron Particles ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Nucleation Effect ◽  
Crystal Fraction ◽  
Light Optical Microscope

Poly(ε-caprolactone) (PCL) was mixed with submicron particles of barium sulfate to obtain biodegradable radiopaque composites. X-ray images comparing with aluminum samples show that 15 wt.% barium sulfate (BaSO4) is sufficient to present radiopacity. Thermal studies by differential scanning calorimetry (DSC) show a statistically significant increase in PCL degree of crystallinity from 46% to 52% for 25 wt.% BaSO4. Non-isothermal crystallization tests were performed at different cooling rates to evaluate crystallization kinetics. The nucleation effect of BaSO4 was found to change the morphology and quantity of the primary crystals of PCL, which was also corroborated by the use of a polarized light optical microscope (PLOM). These results fit well with Avrami–Ozawa–Jeziorny model and show a secondary crystallization that contributes to an increase in crystal fraction with internal structure reorganization. The addition of barium sulfate particles in composite formulations with PCL improves stiffness but not strength for all compositions due to possible cavitation effects induced by debonding of reinforcement interphase.

scholarly journals Surface Characterization and Physiochemical Evaluation of P(3HB-co-4HB)-Collagen Peptide Scaffolds with Silver Sulfadiazine as Antimicrobial Agent for Potential Infection-Resistance Biomaterial

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2454
Author(s):  
Sevakumaran Vigneswari ◽  
Tana Poorani Gurusamy ◽  
Wan M. Khairul ◽  
Abdul Khalil H.P.S. ◽  
Seeram Ramakrishna ◽  
...  
Keyword(s):  
Controlled Release ◽  
Antimicrobial Agent ◽  
Surface Characterization ◽  
Biomedical Application ◽  
Physical And Mechanical Properties ◽  
Silver Sulfadiazine ◽  
Salt Leaching ◽  
Collagen Peptides ◽  
Collagen Peptide ◽  
Peptide Scaffolds

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] is a bacterial derived biopolymer widely known for its unique physical and mechanical properties to be used in biomedical application. In this study, antimicrobial agent silver sulfadiazine (SSD) coat/collagen peptide coat-P(3HB-co-4HB) (SCCC) and SSD blend/collagen peptide coat-P(3HB-co-4HB) scaffolds (SBCC) were fabricated using a green salt leaching technique combined with freeze-drying. This was then followed by the incorporation of collagen peptides at various concentrations (2.5–12.5 wt.%) to P(3HB-co-4HB) using collagen-coating. As a result, two types of P(3HB-co-4HB) scaffolds were fabricated, including SCCC and SBCC scaffolds. The increasing concentrations of collagen peptides from 2.5 wt.% to 12.5 wt.% exhibited a decline in their porosity. The wettability and hydrophilicity increased as the concentration of collagen peptides in the scaffolds increased. In terms of the cytotoxic results, MTS assay demonstrated the L929 fibroblast scaffolds adhered well to the fabricated scaffolds. The 10 wt.% collagen peptides coated SCCC and SBCC scaffolds displayed highest cell proliferation rate. The antimicrobial analysis of the fabricated scaffolds exhibited 100% inhibition towards various pathogenic microorganisms. However, the SCCC scaffold exhibited 100% inhibition between 12 and 24 h, but the SBCC scaffolds with SSD impregnated in the scaffold had controlled release of the antimicrobial agent. Thus, this study will elucidate the surface interface-cell interactions of the SSD-P(3HB-co-4HB)-collagen peptide scaffolds and controlled release of SSD, antimicrobial agent.

Effects of the Different Crystallization Time on Synthesis of Zeolite 4A from by-Products of Polysilicon Production Process

2011 ◽  
Vol 347-353 ◽  
pp. 246-251
Author(s):  
Xing Yong Liu ◽  
Min Li ◽  
Hong Chen ◽  
Wei Wei
Keyword(s):  
Production Process ◽  
Degree Of Crystallinity ◽  
Crystallization Time ◽  
Crystallinity Degree ◽  
Structure Morphology ◽  
Zeolite 4A ◽  
Single Structure ◽  
Ft Ir ◽  
The Degree Of Crystallinity ◽  
By Products

Pure form,single phase and high crystalline zeolite 4A samples were synthesized during hydrothermal treatment of by-products in polysilicon production process. The effects of the different crystallization time on the degree of crystallinity, skeleton structure, morphology, size of the particle and its distribution of zeolite 4A samples were investigated using XRD,FT-IR,SEM and Zetasizer. The results indicated that the zeolite 4A sample featured high crystallinity degree, excellent dispersivity, high purity and single structure.

scholarly journals AFM investigation of hyaline cartilage’s surface destruction

2016 ◽  
Author(s):  
Mikhail Ihnatouski ◽  
Dmitriy Karev ◽  
Boris Karev ◽  
Jolanta Pauk ◽  
Kristina Daunoravičienė
Keyword(s):  
Video Camera ◽  
Optical Microscope ◽  
Collagen Fibers ◽  
Force Microscopy ◽  
Digital Video Camera ◽  
Atomic Force ◽  
Reflected Light ◽  
Longitudinal Orientation ◽  
Chronic Progressive Disease ◽  
Surface Destruction

Introduction: Osteoarthritis is a chronic, progressive disease. The aim of this paper is presenting the AFM investigation of cartilage in relation to the assessment of degenerative changes in the surface of hyaline cartilage. It can be useful in choosing the most effective methods of therapy. Methods: Samples were taken from the cartilage surface of the femoral head after its removal during total hip arthroplasty. Images of the surface of the sample were obtained using an optical microscope equipped with a digital video camera, in the reflected light and by atomic force microscopy. Results: The longitudinal orientation of the collagen fibers and sub-fibers beams on the surface, up to a diameter of 50 nm are identified in non-destroyed area sites. Conclusions: Images of the destroyed areas displaying separately passing collagen fibers, strongly exposed to the surface: the size measured and found substructure.

Crystallization and Melting Behaviors of Polylactic Acid/Thermoplastic Polyurethane Blends

2012 ◽  
Vol 627 ◽  
pp. 156-159 ◽  
Author(s):  
Tien Wei Shyr ◽  
Jung Yang ◽  
Chun Chieh Hu ◽  
Jian Ren Wang ◽  
Chia Hsin Tung
Keyword(s):  
Polylactic Acid ◽  
Thermoplastic Polyurethane ◽  
Crosslinking Agent ◽  
Crystallization Rate ◽  
Optical Microscope ◽  
Avrami Equation ◽  
Isothermal Crystallization Kinetics ◽  
X Ray ◽  
Structure Morphology ◽  
Kinetics Of

A series of blends were prepared by different ratios of polylactic acid (PLA) and thermoplastic polyurethane (TPU) with a crosslinking agent of dicumyl peroxide (DCP). This study focused on the crystal structure, morphology, crystallization, and melting behaviors of PLA/TPU blends using a wide angle x-ray diffractometer (WAXD), a polarizing optical microscope (POM) and a differential scanning calorimeter (DSC). A Modified Avrami equation was applied to analyze non-isothermal crystallization kinetics of PLA/TPU blends. Results show that the nucleation of PLA was enhanced by the added TPU. The spherulitic growth rate, crystallization rate, and crystallinity of the PLA/TPU blends increased with an increase of TPU content. WAXD results show that all of the crystal reflections of PLA/TPU blends related to those of PLA.

Enhancement of the Compressive Strength of 3D-Printed Polylactic Acid(PLA) by Controlling Internal Pattern

2021 ◽  
Vol 1023 ◽  
pp. 75-81
Author(s):  
Aappo Mustakangas ◽  
Atef Hamada ◽  
Antti Järvenpää
Keyword(s):  
Compressive Strength ◽  
3D Printing ◽  
Polylactic Acid ◽  
Optical Microscope ◽  
Fused Filament Fabrication ◽  
Loading Direction ◽  
Compressive Flow ◽  
3D Printed ◽  
Cost Efficient ◽  
Loading Axis

Cost-efficient 3D-printing can create a lot of new opportunities in engineering as it enables rapid prototyping of models and functional parts. In the present study, Polylactic acid (PLA) cubic specimens with different types of infill patterns (IPs), rectilinear, grid and cuboid, were additively manufactured by Fused Filament Fabrication 3D-printing. The PLA cubes are fabricated with one perimeter and different IPs density (10, 20, and 30%). Subsequently, the compressive strengths of the PLA materials were measured in two loading directions, i.e., the layers building direction is parallel (PD) to the loading axis and perpendicular (ND) to the loading direction. An optical microscope was used to examine the deformed IPs in both loading directions. The compressive flow stress curves of the PLA cubes infilled with rectilinear and grid patterns exhibited strong fluctuations with lower compressive strengths in the loading direction along ND. The PLA with 30% grid IP revealed a superior strength of ~12 kN in the loading direction along PD. On the contrary, the same material exhibited a worst compressive strength 3 kN along ND.

Crystalline Morphology and Crystallization Behavior of Poly(Trimethylene Terephthalate)/Functionalized Graphene Oxide Nanocomposites Prepared by Melt Compounding

2019 ◽  
Vol 814 ◽  
pp. 96-101
Author(s):  
Kun Yan Wang
Keyword(s):  
Graphene Oxide ◽  
Crystallization Behavior ◽  
Optical Microscope ◽  
Degree Of Crystallinity ◽  
Functionalized Graphene ◽  
Crystalline Morphology ◽  
Scanning Calorimetry ◽  
Functionalized Graphene Oxide ◽  
Melt Compounding ◽  
Trimethylene Terephthalate

Poly (trimethylene terephthalate) (PTT)/functionalized graphene oxide (fGO) nanocomposites were prepared by melt compounding. The crystalline morphology and crystallization behavior of PTT/fGO with different amounts of fGO were investigated by differential scanning calorimetry (DSC) and polarizing optical microscope (POM). The results show that the crystallization peak shifts to higher temperature after adding fGO, indicating that fGO have a nucleating effect on PTT. The crystallization temperature of nanocomposites increases with increasing content of fGO. The XRD pattern of PTT/fGO nanocomposites almost no change that indicated the degree of crystallinity of the PTT matrix remained unaffected by the addition of fGO. The nanocomposite revealed integrated Maltese crossed spherulitic morphologies. When adding 1% fGO to the PTT, big-sized PTT spherulites occurred and small-sized PTT spherulites were formed around the big-sized PTT spherulites which indicated that the mechanism of nucleation is changed.

scholarly journals Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Athanasios Kotrotsos ◽  
Prokopis Yiallouros ◽  
Vassilis Kostopoulos
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Polylactic Acid ◽  
Physical And Mechanical Properties ◽  
Polymeric Materials ◽  
Cost Effective ◽  
Electrospinning Process ◽  
Wide Range ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

Development of Epoxy Grout Containing Fine Waste from Production of Mineral Wool Board Insulation

2018 ◽  
Vol 878 ◽  
pp. 275-280 ◽  
Author(s):  
Jakub Hodul ◽  
Tomáš Žlebek ◽  
Rostislav Drochytka
Keyword(s):  
Thermal Resistance ◽  
Epoxy Resin ◽  
Filler Content ◽  
Physical And Mechanical Properties ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Mineral Wool ◽  
Raw Material ◽  
Strength Increase ◽  
Economic Point

Within this work, it was experimentally verified that the waste from mineral wool board insulation production (WIRG) with high portion of glass recyclate (> 80%) and no organic material seems like ideal filler for polymer grouting materials. The main objective was to develop a progressive grout on epoxy basis with as high content of this secondary raw material as possible, while achieving physical and mechanical properties as e.g. very fast strength increase and high thermal resistance. With regard to the consistency of epoxy grout in the fresh state, three different filling were tested, namely 60%, 65% and 70%. The grout with lower filling is too fluid, and it is also disadvantageous from an economic point of view because a large amount of epoxy resin is used. On the other hand, at higher filing, it is not possible to mix the filler into epoxy resin properly. Setting of an optimal filler content in the mixture was performed mostly on the basis of the results of compressive and three-point flexural strength test. It was found out that the optimal amount of the filler is 65%. In case of the best formulation with optimal filler content (65% WIRG), the thermal resistance was monitored by determination of the glass transition temperature (Tg) by the dynamic mechanical analysis (DMA) method. Furthermore, the optical microscope with high resolution was used to monitor filler distribution and homogeneity of the hardened developed epoxy grout.

Microstructure, Mechanical Properties, and Corrosion Resistance of Ti-6Mo-6Nb-xSn Alloys for Biomedical Application

2020 ◽  
Vol 988 ◽  
pp. 175-181
Author(s):  
Galih Senopati ◽  
Cahya Sutowo ◽  
Fendy Rokhmanto ◽  
Ika Kartika ◽  
Bambang Suharno
Keyword(s):  
Corrosion Resistance ◽  
Elastic Modulus ◽  
Biomedical Application ◽  
Melting Process ◽  
Optical Microscope ◽  
Hardness Tester ◽  
Ultrasonic Evaluation ◽  
Α Phase ◽  
Lower Corrosion Rate ◽  
Mechanical Properties And Corrosion

Ti-6Al-4V alloy have been used widely for biomedical application, but its elastic modulus is still higher compared with human bone. Moreover, it contains V and Al that have been reported as toxic element. In this study new beta type Ti-6Mo-6Nb-xSn (0, 4, 8 wt.%) have been developed. The aim of this study was to evaluate the Sn addition on microstructural transformation, mechanical behaviour, and corrosion resistance of Ti-6Mo-6Nb-xSn alloys. The Ti-6Mo-6Nb-xSn alloys produced by arc re-melting process and the obtain ingot were characterized using optical microscope, x-ray diffractometer, ultrasonic evaluation, Vicker’s hardness tester, and polarization test to evaluate the corrosion resistance. The result showed that Ti-6Mo-6Nb-8Sn has the lowest elastic modulus and Vicker’s hardness value. The Sn addition could suppress α phase formation. Ti-6Mo-6Nb-8Sn has lower corrosion rate compared to commercial Ti6Al4V.

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