Development of Biodegradable Polymer Blends Based on Chitosan and Polylactide and Study of Their Properties

Composite materials of various compositions based on chitosan and polylactide were obtained in the form of films or porous bulk samples. Preliminarily, poly-D,L-lactide was synthesized by ring-opening polymerization of lactide in the presence of Ti(OiPr)4. Polylactide obtained at components molar ratio [lactide]:[Ti(OiPr)4] = 3:1 had the best molecular weight characteristics at a high product yield. Film composition with the weight ratio chitosan-polylactide 50:50 wt. % was characterized by high mechanical properties. The value of the tensile strength of the film was 72 MPa with a deformation of 10% and an elastic modulus of 40 GPa, which is higher than the tensile strength of native chitosan by ~three times. The observed effect is a consequence of the fact that the chitosan-polylactide composite has an amorphous structure in contrast to the native chitosan, which is proved by X-ray phase analysis. An increase in the elastic modulus of the composite in the range of 20–60 °C in contrast to polylactide was found by dynamic mechanical analysis. The observed effect is apparently caused by the formation of hydrogen bonds between functional groups of chitosan and polylactide which is possible through an increase in polylactide segments mobility when its glass transition temperature is reached. The composite material is biocompatible and characterized by high cellular adhesion of fibroblasts (line hTERT BJ-5ta). Their growth on the composite surface was 2.4 times more active than on native chitosan. Bulk porous samples of the composition with the weight ratio chitosan-polylactide 50:50 wt. % were synthesized by original method in ammonium bicarbonate presence. Samples were characterized by a porosity of 82.4% and an average pore size of 100 microns. The biodegradability of such material and absence of inflammatory processes were proven in vivo by the blood parameters of experimental animals. Thus, materials with the weight ratio chitosan-polylactide 50:50 wt. % are promising for potential use in regenerative medicine.

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Mechanical and Thermal Properties Biodegradable Microcellular Foams Based on Polylactide and Polycaprolactone

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.791-793.274 ◽

2013 ◽

Vol 791-793 ◽

pp. 274-277

Author(s):

Teng Fei Shen ◽

Ying Juan Sun

Keyword(s):

Tensile Strength ◽

Thermal Properties ◽

Elastic Modulus ◽

Coupling Effect ◽

Average Pore Size ◽

Mechanical And Thermal Properties ◽

Average Pore ◽

Microcellular Foams ◽

Final Microstructure ◽

Lower Glass Transition Temperature

In this work, the producing of a series of biodegradable polylactide (PLA)/polycaprolactone (PCL) microcellular foams by rapid solvent casting method was investigated and discussed. Scanning electron microscopy (SEM) showed the average pore size in the structure was around 7 μm and the final microstructure was a combination of open and closed cells. The effect of PCL segments added on the mechanical and thermal behaviors was studied. According to the results, PLA/PCL biomaterial had lower glass transition temperature (Tg) in comparison with neat PLA polymer. In addition, the tensile strength and elastic modulus became poor when PCL added in. For obtained better mechanical and thermal properties, EC-blocked polyisocyanate (EC-bp), which was synthesized from reaction of toluene 2, 4-diisocyanate with dimethylol propionic acid and trimethylolpropane followed by addition of ethyl cellosolve (EC), were introduced. It was found that the tensile strength and elastic modulus were significantly increased by addition of EC-bp, which can be explained by coupling effect occurred between PLA and PCL.

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PHOTOCATALYTIC REMOVAL OF PHENOL OVER MESOPOROUS ZnO/TiO2 COMPOSITES

Jurnal Teknologi ◽

10.11113/jt.v80.11209 ◽

2018 ◽

Vol 80 (2) ◽

Cited By ~ 1

Author(s):

Klinsmann Cheong Lee Khang ◽

Mohd Hayrie Mohd Hatta ◽

Siew Ling Lee ◽

Leny Yuliati

Keyword(s):

Pore Size ◽

Uv Light ◽

Average Pore Size ◽

Anatase Tio2 ◽

Light Irradiation ◽

Molar Ratio ◽

Average Pore ◽

Uv Light Irradiation ◽

Photocatalytic Removal ◽

Mesoporous Zno

A series of mesoporous ZnO/TiO2 composites were successfully synthesized using cetyltrimethylammonium bromide surfactant. The composites of different Zn:Ti molar ratios (0.5:1, 0.75:1, and 1:1) were prepared by impregnating ZnO onto mesoporous TiO2. XRD results verified co-existence of both anatase TiO2 and hexagonal wurtzite ZnO in the ZnO/TiO2 composites. Based on the Tauc plots, all the composites showed almost the same band gap energy of approximately 3.21 eV. The fourier transform infrared spectroscopy results successful covering of ZnO on the surface of the TiO2 as the hydrophilicity property of TiO2 decreased remarkably with the loading of ZnO in the composites. N2 adsorption-desorption isotherms of the samples exhibited type-IV isotherm with a hysteresis loop. The Barrett-Joyner-Halenda pore size distribution revealed that the average pore size of the composites was around 3.6 nm, indicating the formation of mesopores dominantly in the samples. The photocatalytic removal of phenol over the samples under UV light irradiation after 3 h decreased in the order: ZnO/TiO2 composites > anatase TiO2 (with surfactant) > anatase TiO2 (without surfactant) > ZnO. The composite with Zn:Ti molar ratio of 0.75:1 has achieved the highest photocatalytic activity of 36.5% in the removal of phenol under UV light irradiation for 3 h.

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Effect of Beating and Fibre Furnish on the Properties of Silk Paper

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.55-57.1753 ◽

2011 ◽

Vol 55-57 ◽

pp. 1753-1758

Author(s):

Li Zheng Sha ◽

Hui Fang Zhao

Keyword(s):

Tensile Strength ◽

Pore Size ◽

Average Pore Size ◽

Silk Fibre ◽

Upward Trend ◽

Average Pore ◽

Tensile Index ◽

Plant Fibre

The aim of this work is to study the influence of beating and refining as well as the fibre furnish on the properties of silk paper, such as air permeance, softness, pore size, tensile index and burst index. The results showed that the beating characteristic of silk fibre was similar to that of plant fibre, they all had the characteristic of fibrillation. Silk paper had excellent softness and air permeance when the beating degree of silk pulp was 20 °SR, 181.3 μm/Pa·s and 2.5 mN·m2/g respectively, which was superior to paper made from plant fibres of the same beating degree. The minimum average pore size of silk paper was 5.11 μm at the beating degree of 20 °SR, and it decreased with the increase of beating degree, reached 0.79 μm at the beating degree of 67 °SR. With the increase of beating degree, the tensile index of silk paper increased at first, and then decreased. The burst index of silk paper showed a upward trend, but the softness and air permeance of it constantly decreased. The tensile strength of paper made from mixed-furnish pulp consisting of silk and softwood reached the maximum when the amount of silk fibre was 4%, and its air permeance increased with the increase of silk fibre.

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Evaluation of dolomite as catalyst in the transesterification reaction using palm oil (RBD)

DYNA ◽

10.15446/dyna.v86n209.74126 ◽

2019 ◽

Vol 86 (209) ◽

pp. 180-187

Author(s):

Stephanie Alexa Ñústez Castaño ◽

Duvan Oswaldo Villamizar Castro ◽

Edgar Mauricio Vargas Solano

Keyword(s):

Palm Oil ◽

Batch Reactor ◽

Methyl Esters ◽

Average Pore Size ◽

Molar Ratio ◽

Reaction Conditions ◽

Average Pore ◽

X Ray ◽

Rbd Palm Oil ◽

Methyl Ester Content

In this study, the catalytic activity of dolomite was evaluated for the transesterification of Colombian RBD palm oil with methanol, carried out in a batch reactor at 333,15K and 600rpm. The activated dolomites (calcined at 1073.15K for 2h) were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Hammett indicators method, and quantification of the surface area, average pore size and average pore volume BET. The influence of reaction variables such as catalyst amount (%wt /wt) and methanol / palm oil molar ratio (mole/mole) was investigated. Under the suitable reaction conditions, the amount of calcined dolomite equal to 4% (wt /wt) based on the weight of oil, the methanol-oil molar ratio equal to 9:1, and the reaction time = 1h, the methyl ester content of 82.67% of fatty acid methyl esters (FAME) can be achieved.

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Design and Preparation of an Electrospun Biomaterial Surgical Patch

Journal of Bioactive and Compatible Polymers ◽

10.1177/0883911509103559 ◽

2009 ◽

Vol 24 (1_suppl) ◽

pp. 158-168 ◽

Cited By ~ 9

Author(s):

Hai Lu ◽

Wei-Jun Chen ◽

Yan Xing ◽

Da-Jun Ying ◽

Bo Jiang

Keyword(s):

Tensile Strength ◽

Elastic Modulus ◽

Yield Strength ◽

Collagen Type ◽

Sem Images ◽

Significant Potential ◽

Clinical Transplantation ◽

Porcine Pericardium ◽

Porous Morphology

A biomaterial patch of electrospun collagen type fibers was designed and produced by electrospinning seven different concentrations (8%-20% w/v) of collagen solutions. The tensile strength, yield strength, and elastic modulus of the electrospun collagen fibrous patches were found to be suitable for clinical transplantation. No significant differences versus fresh porcine pericardium as controls were observed. The SEM images of the groups showed that the patches were smooth with uniform interwoven and porous morphology. The fibrous patches were biocompatible and did not elicit local or systemic toxic effects when implanted in vivo. These electrospun collagen fibrous patches have significant potential as surgical biomaterial patches.

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Novel Micro-CT Based 3-Dimentional Structural Analyses of Porous Biomaterials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.967 ◽

2007 ◽

Vol 330-332 ◽

pp. 967-970 ◽

Cited By ~ 2

Author(s):

B. Otsuki ◽

Mitsuru Takemoto ◽

Shunsuke Fujibayashi ◽

Masashi Neo ◽

Tadashi Kokubo ◽

...

Keyword(s):

Network Structure ◽

Bone Ingrowth ◽

Average Pore Size ◽

Three Dimensional ◽

Porous Titanium ◽

Titanium Implants ◽

Average Pore ◽

Tissue Ingrowth ◽

Porous Biomaterials

A porous structure comprises pores and pore throats with a complex three-dimensional network structure, and many investigators have described the relationship between average pore size and the amount of bone ingrowth. However, the influence of network structure or pore throats for tissue ingrowth has rarely been discussed. Bioactive porous titanium implants with 48% porosity were analyzed using specific algorithms for three-dimensional analysis of interconnectivity based on a micro focus X-ray computed tomography system. In vivo histological analysis was performed using the very same implants implanted into the femoral condyles of male rabbits for 6 weeks. This matching study revealed that more poorly differentiated pores tended to have narrow pore throats, especially in their shorter routes to the outside. Data obtained suggest that this sort of novel analysis is useful for evaluating bone and tissue ingrowth into porous biomaterials.

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Structural Characteristics and Mechanical Properties of Biomedical Porous Ti-10Mo Alloy Fabricated by Selective Laser Sintering

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.520.234 ◽

2012 ◽

Vol 520 ◽

pp. 234-241

Author(s):

Fang Xia Xie ◽

Xin Lu ◽

Xin Bo He ◽

Xuan Hui Qu

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Sintering Temperature ◽

Structural Characteristics ◽

Average Pore Size ◽

Selective Laser Sintering ◽

Compressive Yield Strength ◽

Average Pore ◽

Porous Ti ◽

Interconnected Pores

Ti-Mo alloy is one of the most prospective metallic biomaterials for implant application because of its low elastic modulus, high corrosion resistance and tissue compatibility. A complex-shaped porous Ti-10Mo alloy from a mixture of elemental metal powders and polymer binders was processed by selective laser sintering forming, followed by thermal debinding and sintering in vacuum. The effects of processing parameters on structural characteristics and mechanical properties were studied. The results indicate that the pore characteristic parameters, matrix microstructure and mechanical properties strongly depend on the sintering temperature. Specimens sintered at 1100 °C exhibit a higher porosity of 52.41%, and possess many three-dimensionally interconnected pores with an average size of 200 μm, and the matrix is dominated by α and β phases, and meanwhile the alloy exhibits a compressive yield strength of 95.59 MPa and an elastic modulus of 4.89 GPa at room temperature. With the rise in sintering temperature, both the porosity and the average pore size of specimens gradually decrease, and the interconnected pores tend to be closed. Specimens sintered at 1400 °C are characterized by a porosity of 26.32% and an average pore size of 60 μm with a compressive yield strength of 440 MPa and an elastic modulus of 35.26 GPa.

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Fabrication and Characterization of PCL/GE-Based Electrospun Nanofibers for Tissue Engineering and Drug Delivery Application

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.695.195 ◽

2014 ◽

Vol 695 ◽

pp. 195-198

Author(s):

Lor Huai Chong ◽

Mim Mim Lim ◽

Naznin Sultana

Keyword(s):

Drug Delivery ◽

Tissue Engineering ◽

Average Pore Size ◽

Weight Ratio ◽

Electrospun Nanofibers ◽

Average Pore ◽

X Ray ◽

Fabrication And Characterization ◽

The Relationship

Tissue engineering (TE) provides an alternative option to solve limitation of organ and tissue transplantation issues. Fabrication of scaffold is a major challenge because it needs to provide a suitable medium for cell growing and drug delivery which enhances cell transplantation efficiency. The porosity, biodegradability and biocompatibility are the important properties in fabricating a scaffold. Our previous work had found that electrospinning of Polycarprolactone (PCL)/ Gelatin (GE)-based nanofibers in 14% w/v polymer solution in 18kV showed the best results in morphology, average diameters, average pore size and hydrophilicity. Hence, in this project, we are interested to study the relationship between weight ratio of PCL and GE in the same concentration (14%) to the morphology, degradation rate and porosity of nanofibers. Experimental results showed that PCL with 1.2g and GE with 0.2g was able to produce better nanofibers. The sample was then further deployed in drug (tetracycline hydrochloride) loading and it was successfully loaded proven by Energy Dispersive X-Ray (EDX) Spectrum. These nanofibers are predicted to be potentially useful for drug delivery and TE application.

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Sol-Gel Processed Cobalt-Doped Methylated Silica Membranes Calcined under N2 Atmosphere: Microstructure and Hydrogen Perm-Selectivity

Materials ◽

10.3390/ma14154188 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4188

Author(s):

Lunwei Wang ◽

Jing Yang ◽

Ruihua Mu ◽

Yingming Guo ◽

Haiyun Hou

Keyword(s):

Average Pore Size ◽

Sol Gel ◽

Total Pore Volume ◽

Molar Ratio ◽

Average Pore ◽

Silica Membranes ◽

Physical Chemical ◽

N2 Atmosphere ◽

Coating Method ◽

Gel Technique

Methyl-modified, cobalt-doped silica (Co/MSiO2) materials were synthesized by sol-gel technique calcined in N2 atmospheres, and membranes were made thereof by coating method. The effects of Co/Si molar ratio (nCo) on the physical-chemical constructions of Co/MSiO2 materials and microstructures of Co/MSiO2 membranes were systematically investigated. The gas permeance performance and hydrothermal stability of Co/MSiO2 membranes were also tested. The results show that the cobalt element in Co/MSiO2 material calcined at 400 °C exists not only as Si–O–Co bond but also as Co3O4 and CoO crystals. The introduction of metallic cobalt and methyl can enlarge the total pore volume and average pore size of the SiO2 membrane. The activation energy (Ea) values of H2, CO2, and N2 for Co/MSiO2 membranes are less than those for MSiO2 membranes. When operating at a pressure difference of 0.2 MPa and 200 °C compared with MSiO2 membrane, the permeances of H2, CO2, and N2 for Co/MSiO2 membrane with nCo = 0.08 increased by 1.17, 0.70, and 0.83 times, respectively, and the perm-selectivities of H2/CO2 and H2/N2 increased by 27.66% and 18.53%, respectively. After being steamed and thermally regenerated, the change of H2 permeance and H2 perm-selectivities for Co/MSiO2 membrane is much smaller than those for MSiO2 membrane.

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The Effect of Pore Directionality of Collagen Scaffolds on Cell Differentiation and In Vivo Osteogenesis

Polymers ◽

10.3390/polym13183187 ◽

2021 ◽

Vol 13 (18) ◽

pp. 3187

Author(s):

Miguelangel Moncayo-Donoso ◽

Gustavo A. Rico-Llanos ◽

Diego A. Garzón-Alvarado ◽

José Becerra ◽

Rick Visser ◽

...

Keyword(s):

Bone Growth ◽

Cell Attachment ◽

Average Pore Size ◽

Bone Matrix ◽

Osteoblastic Differentiation ◽

Collagen Scaffolds ◽

Average Pore ◽

Native Bone

Although many bone substitutes have been designed and produced, the development of bone tissue engineering products that mimic the microstructural characteristics of native bone remains challenging. It has been shown that pore orientation within collagen scaffolds influences bone matrix formation by the endochondral route. In addition, that the unidirectional orientation of the scaffolds can limit the growth of blood vessels. However, a comparison between the amount of bone that can be formed in scaffolds with different pore orientations in addition to analyzing the effect of loading osteogenic and proangiogenic factors is still required. In this work we fabricated uni- and multidirectional collagen sponges and evaluated their microstructural, physicochemical, mechanical and biological characteristics. Although the porosity and average pore size of the uni- and multidirectional scaffolds was similar (94.5% vs. 97.1% and 260 µm vs. 269 µm, respectively) the unidirectional sponges had a higher tensile strength, Young’s modulus and capacity to uptake liquids than the multidirectional ones (0.271 MPa vs. 0.478 MPa, 9.623 MPa vs. 3.426 MPa and 8000% mass gain vs. 4000%, respectively). Culturing of rat bone marrow mesenchymal stem cells demonstrated that these scaffolds support cell growth and osteoblastic differentiation in the presence of BMP-2 in vitro, although the pore orientation somehow affected cell attachment and differentiation. The evaluation of the ability of the scaffolds to support bone growth when loaded with BMP-2 or BMP-2 + VEGF in an ectopic rat model showed that they both supported bone formation. Histological analysis and quantification of mineralized matrix revealed that the pore orientation of the collagen scaffolds influenced the osteogenic process.

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