The Energy Barriers Model for the Physical Description of the Viscoelasticity of Synthetic Polymers: Application to the Uniaxial Orientational Drawing of Polyamide Films

2013 ◽  
Vol 52 (12) ◽  
pp. 1829-1847 ◽  
Author(s):  
P. P. Rymkevich ◽  
A. A. Romanova ◽  
V. V. Golovina ◽  
A. G. Makarov
Keyword(s):  
Synthetic Polymers ◽  
Energy Barriers ◽  
Physical Description ◽  
Orientational Drawing

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

Simple Modification Measurement of Photodegradability of Polymers by using Photo-induced Chemiluminescence Technique

2013 ◽  
Vol 10 (2) ◽  
pp. 51
Author(s):  
Siti Farhana Zakaria ◽  
Keith R Millington
Keyword(s):  
Free Radicals ◽  
Organic Materials ◽  
Oxidative Degradation ◽  
Working Life ◽  
Bimolecular Reaction ◽  
Synthetic Polymers ◽  
Accelerated Weathering ◽  
Simple Modification ◽  
Uv Absorbers ◽  
Irradiation Period

Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.

Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

2019 ◽  
Author(s):  
Michael J. Strauss ◽  
Darya Asheghali ◽  
Austin Evans ◽  
Rebecca Li ◽  
Anton Chavez ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Synthetic Polymers ◽  
Young’S Moduli ◽  
Structural Rigidity ◽  
Assembly Mechanism ◽  
Low Dimensionality ◽  
Harsh Conditions

<p>Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length or strength of the resultant nanotubes. Imine-linked macrocycles were recently found to assemble into high-aspect ratio (>10<sup>3</sup>), lyotropic nanotubes in the presence of excess acid. Yet these harsh conditions are incompatible with many functional groups and processing methods, and lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine-2,6-diimine-linked macrocycles that assemble into high-aspect ratio nanotubes in the presence of less than 1 equiv of CF<sub>3</sub>CO<sub>2</sub>H per macrocycle. Analysis by gel permeation chromatography and fluorescence spectroscopy revealed a cooperative self-assembly mechanism. Nanofibers obtained by touch-spinning the pyridinium-based nanotubes exhibit Young’s moduli of 1.48 GPa, which exceeds that of many synthetic polymers and biological filaments. These findings will enable the design of structurally diverse nanotubes from synthetically accessible macrocycles. </p>

Catalytic Hydrocracking of Synthetic Polymers into Grid-Compatible Gas Streams

2020 ◽  
Author(s):  
Wei-Tse Lee ◽  
Felix D. Bobbink ◽  
Antoine P. van Muyden ◽  
Kun-Han Lin ◽  
Clémence Corminboeuf ◽  
...  
Keyword(s):  
Synthetic Polymers ◽  
Gas Streams

scholarly journals Porous scaffolds with the structure of an interpenetrating polymer network made by gelatin methacrylated nanoparticle-stabilized high internal phase emulsion polymerization targeted for tissue engineering

RSC Advances ◽  
2021 ◽  
Vol 11 (37) ◽  
pp. 22544-22555
Author(s):  
Atefeh Safaei-Yaraziz ◽  
Shiva Akbari-Birgani ◽  
Nasser Nikfarjam
Keyword(s):  
Tissue Engineering ◽  
Extracellular Matrix ◽  
Cell Growth ◽  
Polymer Network ◽  
Synthetic Polymers ◽  
Tissue Scaffolds ◽  
Interpenetrating Polymer Network ◽  
Porous Scaffolds ◽  
Promising Strategy ◽  
Internal Phase

The interlacing of biopolymers and synthetic polymers is a promising strategy to fabricate hydrogel-based tissue scaffolds to biomimic a natural extracellular matrix for cell growth.

scholarly journals Chemical conjugation of nucleic acid aptamers and synthetic polymers

2021 ◽  
Author(s):  
Maria Nerantzaki ◽  
Capucine Loth ◽  
Jean-Francois Lutz
Keyword(s):  
Nucleic Acid ◽  
Synthetic Polymers ◽  
Specific Sequence ◽  
Biological Targets ◽  
Nucleic Acid Aptamers ◽  
Chemical Conjugation ◽  
Sequence Dependent

Nucleic acid aptamers are chemically-synthesized single-stranded oligonucleotides that fold into specific sequence-dependent configurations. Due to their exceptional recognition properties towards a variety of biological targets, they find applications in many...

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