Production and Properties of Polypropylene Track Membranes

1997 ◽  
Vol 62 (5) ◽  
pp. 752-760 ◽  
Author(s):  
Lyubov I. Kravets ◽  
Sergei N. Dmitriev ◽  
Pavel Yu. Apel
Keyword(s):  
Thermal Stability ◽  
Physicochemical Properties ◽  
Mechanical Strength ◽  
Polymer Films ◽  
Heavy Ions ◽  
Physicochemical Treatment ◽  
Pore Sizes ◽  
High Homogeneity ◽  
Track Membranes ◽  
Resistance To Oxidation

This paper describes results of the method of manufacturing the polypropylene track membranes produced by physicochemical treatment under irradiation of accelerated heavy ions of polymer films. The developed method allows to produce membranes with pores of 0.1-0.2 μm in diameter and more, with an improved structural and physicochemical properties. Polypropylene track membranes of a novel sample are characterized by high homogeneity of pore sizes in magnitude, considerable mechanical strength, advanced thermal stability and resistance to oxidation in aggressive media. It opens new fields for their usage.

scholarly journals Biopolymer Composites as an Alternative to Materials for the Production of Ecological Packaging

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 592
Author(s):  
Miroslawa Prochon ◽  
Oleksandra Dzeikala
Keyword(s):  
Thermal Stability ◽  
Polyvinyl Alcohol ◽  
Physicochemical Properties ◽  
Mechanical Strength ◽  
Optical Transmission ◽  
Casting Process ◽  
Cross Linking ◽  
Natural Sources ◽  
Biopolymer Composites ◽  
Selection Of

The problem of plastic waste has long been a concern for governments and society. However, huge amounts of plastic are still being released into the oceans and the environment. One possible solution is to replace plastics with materials that are more both biodecomposable and biodegradable. The most environmentally friendly materials are made of natural ingredients found in nature, although not all of them can be called biodegradable. In this study, we set out to create a new composite with functional properties that could replace commonly used disposable packaging. To ensure the competitiveness of our solution, we used inexpensive and readily available components, such as gelatin G HOOCCH2CH2C(R1)NHCOCH2NH2 (where R1 is a continuation of the peptide chain), polyvinyl alcohol PVA CH2CH(OH), and glycerin G HOCH2CH(CH2OH)O. The ingredients used in the research come from natural sources; however, they are chemically processed. Some of them, such as polyvinyl alcohol, for example, are biodegradable. With the appropriate selection of the components, in the casting process, the intermixed components made it possible to produce materials that were characterized by good physicochemical properties, including thermal stability, optical transmission of UV-Vis light, cross-linking density, and mechanical strength. The most favorable parameters of thermal stability were observed in casein-containing gelatine forms. The best cross-linking density was obtained in the case of gelatin–glycerine systems. Composite containing caseins distinguished by the highest resistance to flammability, increased thermal stability, flexibility, and greater hardness compared to other composites.

Polycarbosilane-modified styrene-based polymers with ultra-low dielectric constant, greatly enhanced mechanical strength and thermal stability

2018 ◽  
Vol 98 ◽  
pp. 347-353 ◽  
Author(s):  
Yawen Huang ◽  
Lili Liu ◽  
Shengbo Zhang ◽  
Hongtao Yu ◽  
Junxiao Yang
Keyword(s):  
Thermal Stability ◽  
Dielectric Constant ◽  
Mechanical Strength ◽  
Low Dielectric Constant ◽  
Low Dielectric

scholarly journals Fabrication of Porous Al2O3 Ceramics with Submicron-Sized Pores Using a Water-Based Gelcasting Method

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1784 ◽  
Author(s):  
Zhihong Yang ◽  
Nan Chen ◽  
Xiaomei Qin
Keyword(s):  
Mechanical Strength ◽  
Water Content ◽  
Sintering Temperature ◽  
Al2o3 Content ◽  
Volume Fractions ◽  
Pore Sizes ◽  
Water Based ◽  
Low Levels ◽  
Median Pore

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al2O3 ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al2O3 content at low levels. By controlling the water content in the ceramic slurries and the sintering temperature of the green samples, the volume fractions and the size characteristics of the pores in the porous Al2O3 can be readily obtained. For the porous Al2O3 ceramics prepared with 30 vol.% Al2O3 content in the slurries, their open porosities were from 38.3% to 47.2%, while their median pore sizes varied from 299.8 nm to 371.9 nm. When there was more Al2O3 content in the slurries (40 vol.% Al2O3), the porous Al2O3 ceramics had open porosities from 37.0% to 46.5%, and median pore sizes from 355.4 nm to 363.1 nm. It was found that a higher sintering temperature and Al2O3 content in the slurries increased the mechanical strength of the porous Al2O3 ceramics.

scholarly journals Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

2019 ◽  
Vol 4 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Janusz Szklarzewicz ◽  
Anna Jurowska ◽  
Maciej Hodorowicz ◽  
Ryszard Gryboś
Keyword(s):  
Thermal Stability ◽  
Schiff Base ◽  
Solid State ◽  
Physicochemical Properties ◽  
General Formula ◽  
Oxidation State ◽  
Magnetic Moment ◽  
Tridentate Ligand ◽  
Schiff Base Ligands ◽  
Long Period

The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5-dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes.

Structure–property relation of porous poly (l-lactic acid) scaffolds fabricated using organic solvent mixtures and controlled cooling rates and its bio-compatibility with human adipose stem cells

2018 ◽  
Vol 33 (4) ◽  
pp. 397-415 ◽  
Author(s):  
Harish Chinnasami ◽  
Jeff Gimble ◽  
Ram V Devireddy
Keyword(s):  
Stem Cells ◽  
Cell Proliferation ◽  
Lactic Acid ◽  
Phase Separation ◽  
Mechanical Strength ◽  
Separation Method ◽  
Thermally Induced Phase Separation ◽  
Cooling Rates ◽  
Thermally Induced ◽  
Pore Sizes

Thermally induced phase separation method was used to make porous three-dimensional poly (l-lactic acid) scaffolds. The effect of imposed thermal profile during freezing of the poly (l-lactic acid) in dioxane solution on the scaffold was characterized by their micro-structure, porosity (%), pore sizes’ distribution, and mechanical strength. The porosity (%) decreased considerably with increasing concentrations of poly (l-lactic acid) in the solution, while a decreasing trend was observed with increasing cooling rates. The mechanical strength increases with increase in poly (l-lactic acid) concentration and also with increase in the cooling rate for both types of solvents. Therefore, mechanical strength was increased by higher cooling rates while the porosity (%) remained relatively consistent. Scaffolds made using higher concentrations of poly (l-lactic acid; 7% and 10% w/v) in solvent showed better mechanical strength which improved relatively with increasing cooling rates (1°C–40°C/min). This phenomenon of enhanced structural integrity with increasing cooling rates was more prominent in scaffolds made from higher initial poly (l-lactic acid) concentrations. Human adipose–derived stem cells were cultured on these scaffold (7% and 10% w/v) prepared by thermally induced phase separation at all cooling rates to measure the cell proliferation efficiency as a function of their micro-structural properties. Mean pore sizes played a crucial role in cell proliferation than percent porosity since all scaffolds were >88% porous. The viability percent of human adipose tissue–derived adult stem cells increased consistently with longer periods of culture. Thus, poly (l-lactic acid) scaffolds prepared by thermally controlled thermally induced phase separation method could be a prime candidate for making ex vivo tissue-engineered grafts for surgical implantation.

scholarly journals Synthesis, characterization and physicochemical studies of copolymers of aniline and 3-nitroaniline

2019 ◽  
Vol 77 (9) ◽  
pp. 4469-4488 ◽  
Author(s):  
Umesh Somaji Waware ◽  
A. M. S. Hamouda ◽  
Dipanwita Majumdar
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Physicochemical Properties ◽  
Electrochemical Sensors ◽  
Protective Coatings ◽  
Molar Ratio ◽  
Energy Storage Devices ◽  
Visible Absorption ◽  
Storage Devices ◽  
Morphological Studies

Abstract Polyaniline (PA), the versatile conducting polymer, owing to its tunable optoelectronic properties, facile preparation methodology and reversible redox behavior, has elicited much interest among current researchers, particularly in the fields of energy generation storage devices, protective coatings and electrochemical sensors. However, its commercialization has been much restricted due to low solution processability and thermal stability. Recent studies reveal that the above-mentioned challenges can effectively be addressed by copolymerization of PA with suitable components. In addition, the properties of copolymers could be modified and tuned by varying the monomer ratios. Thus, the present work is concerned with the fabrication of poly(aniline-co-3-nitroaniline) with varying compositions obtained by in situ oxidative copolymerization of aniline and 3-nitroaniline by altering the molar ratio of monomers. Optimization of the physicochemical properties such as UV–visible absorption, solubility, thermal stability, electrical conductivity and dielectric signatures, particle size and morphology was achieved by varying the composition of monomeric substituents in these copolymers. Smoother morphology of the copolymer films was revealed by morphological studies via AFM technique and supported by particle size distribution study. The physicochemical trends demonstrated that proper proportions of nitro (–NO2) group in the polymer chain are essential to achieve desired optimal physicochemical properties. Therefore, copolymers are ideally appropriate for multifaceted applications and would promote wider usage of conjugated polymers in various fields of organic-based optoelectronic as well as energy storage devices in the near future.

scholarly journals Efficient Synthesis of PVDF/PI Side-by-Side Bicomponent Nanofiber Membrane with Enhanced Mechanical Strength and Good Thermal Stability

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Ming Cai ◽  
Hongwei He ◽  
Xiao Zhang ◽  
Xu Yan ◽  
Jianxin Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Mechanical Strength ◽  
Polyvinylidene Fluoride ◽  
Chemical Structure ◽  
Electrospun Fiber ◽  
Nanofiber Membrane ◽  
Application Range ◽  
Good Thermal Stability ◽  
Filtration Properties

Bicomponent composite fibers, due to their unique versatility, have attracted great attention in many fields, such as filtration, energy, and bioengineering. Herein, we efficiently fabricated polyvinylidene fluoride/polyimide (PVDF/PI) side-by-side bicomponent nanofibers based on electrospinning, which resulted in the synergism between PVDF and PI, and eventually obtained the effect of 1 + 1 > 2. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and chemical structure of nanofibers, indicating that a large number of side-by-side nanofibers were successfully prepared. Further, the thermal stability, mechanical strength, and filtration properties of PVDF/PI were carefully investigated. The results revealed that the bicomponent nanofibers possessed both good mechanical strength and remarkable thermal stability. Moreover, the mechanical properties of PVDF/ PI were strengthened by more than twice after the heat treatment (7.28 MPa at 25 °C, 15.49 MPa at 230 °C). Simultaneously, after the heat treatment at 230 °C for 30 min, the filtration efficiency of PVDF/PI membrane was maintained at about 95.45 ± 1.09%, and the pressure drop was relatively low. Therefore, the prepared PVDF/PI side-by-side bicomponent nanofibers have a favorable prospect of application in the field of medium- and high-temperature filtration, which further expands the application range of electrospun fiber membranes.

Studies of Adsorbents for Hemoperfusion in Artificial Liver Support. I. Preparation and in Vitro Studies of Cross-Linked Agarose Beads Entrapped Activated Charcoal (CAAC)

1981 ◽  
Vol 4 (4) ◽  
pp. 200-204 ◽  
Author(s):  
C.X. Xu ◽  
X.J. Tang ◽  
Z. Niu ◽  
Z.M. Li
Keyword(s):  
Thermal Stability ◽  
Blood Flow ◽  
High Temperature ◽  
Mechanical Strength ◽  
Activated Charcoal ◽  
Artificial Liver ◽  
Liver Support ◽  
Artificial Liver Support ◽  
Agarose Beads

A new method for the preparation of the cross-linked agarose beads entrapped activated charcoal (CAAC) is reported. Since the agarose-encapsulated adsorbents reported elsewhere cannot stand high temperature for sterilization, the CAAC has the advantage of thermal stability to withstand autoclave at 121°C. for ½ hour without breaking up or melting. A further advantage of CAAC is that the adsorbent has a much better consistency with good mechanical strength and elasticity, so that it can be formed into beads of a diameter less than 1 mm. This will not only give a better adsorption capacity than larger beads, but can also assure a better blood flow than soft beads which usually interfere in hemoperfusion due to compacting and sludging. Preliminary investigations indicate that the CAAC is relatively hemocompatible.

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