Surface Phenomena in the Structural and Mechanical Behaviour of Solid Polymers

Streltsov

Малахов

et al. 2020

Polymer International

This work addresses the phenomenon of the development of a patterned surface relief on polymer films via different modes of environmental crazing. Commercial films of semicrystalline poly(tetrafluoroethylene) (PTFE) and amorphous glassy poly(ethylene terephthalate) (PET) were subjected to tensile drawing in the presence of physically active liquid environments (carbon tetrachloride or aliphatic alcohols). The structure parameters and wettability of the modified films were studied by AFM, SEM, profilometer measurements and contact angle measurements. Environmental intercrystallite crazing of PTFE is accompanied by the development of an unstable structure with a high free surface, which experiences marked strain recovery upon unloading. As a result of the relief formation, PTFE hydrophobicity is enhanced (the water contact angle increases by 25°). Classical environmental crazing of PET films is accompanied by the formation of an anisotropic surface relief which is an assembly of crazes oriented perpendicular to the direction of tensile drawing, thus leading to the phenomenon of anisotropic wetting. The proposed approach for structural surface modification makes it possible to use the advantages of surface instability and spontaneous self-organization of the polymer towards the development of a unique surface microrelief.

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Surface modification of poly(tetrafluoroethylene) and poly(ethylene terephthalate) films via environmental crazing

Streltsov

Малахов

et al. 2020

Polymer International

“…The operational properties of materials, as well as their physical and chemical characteristics, substantially depend on the structure of the cured polymer, the configuration and flexibility of macromolecules, their kinetic properties [1,2]. An important task of technological progress is still the development of technologies providing lower energy consumption and improved working conditions, what allows increasing the service life of products and equipment.…”

mentioning

confidence: 99%

Study of Radiation-Chemical Structuring of Compositions Based on Epoxy Oligomers

Podhornaya

Avramenko

Karandashov

2020

EEJP

The processes of radiation-chemical structuring of modified epoxy acrylic compositions were studied depending on the nature of epoxy oligomers and modifiers. ED-20 and ED-22 grades epoxy oligomers were chosen as epoxidian oligomers; 3,4epoxyhexahydrobenzal-3,4-epoxy-1,1-bis(hydroxymethyl)cyclohexane (UP-612 grade), 3,4-epoxycyclohexylmethyl-3,3epoxycyclohexanecarboxylate (UP-632 grade) were chosen as cycloaliphatic oligomers; diethylene glycol diglycidyl ether (DEG) was chosen as aliphatic oligomer. To modify the epoxy oligomers, unsaturated acrylic monomers, such as acrylic acid and methyl acrylic acid ester; aromatic and aliphatic oligoester acrylates, such as α,ω-methacryl(bis-diethylene glycol)phthalate (MDP-1 grade), α,ω-methacryldi(diethyleneglycolphthalate) (MDP-2 grade), α,ω-methacryl(bis-triethyleneglycol)phthalate (MGP-9 grade) and atri-(oxyethylene)-α,ω-dimethacrylate (TGM-3 grade); condensation product of linseed oil dimerized fatty acids and polyethylenepolyamine, such as oligoamide L-20 grade; condensation product of ricinoleic acid, castor oil and maleic anhydride, such as unsaturated polyester PE-220, were used. The thermophysical and relaxation properties of cross-linked polymers, obtained under exposure to γ-radiation of Co 60 and electrons accelerated by the absorbed radiation dose of 50-150 kGy at the beam current of 2-4 mA and electron energy of 240-300 keV, were studied. The distance from the exhaust window of the accelerator to the irradiated surface of the samples was 63-80 mm. The thermophysical properties of the cured polymers were evaluated using thermomechanical studies on a thermomechanograph with the temperature rise of 1 о /min and the pressure of 0.54 MPa in the temperature range of 293-673 K, as well as the differential thermal and thermogravimetric analyzes on a system derivatograph by L. Paulik, R. Paulik, L. Erdei in the temperature range of 293-973 K with the rise rate of 7 о /min. The relaxation properties and molecular mobility of the cross-linked polymers were studied by the dielectric method. The dielectric loss tangent was determined in the temperature range of 143-393K at the frequency of 1 kHz using a digital automatic bridge of alternating current R-589. The test sample temperature was measured using a potentiometer on a copper-constantan thermocouple, which was placed in the measuring cell along with the test sample. The samples were cooled by placing the cell in a vessel with liquid nitrogen. As a result of the studies, the influence of the chemical nature of epoxy oligomers and unsaturated modifiers on the processes of structure formation and molecular mobility of polymers, obtained under conditions of radiation-chemical curing, was established. It was determined, that when modifying epoxy oligomers with acrylic acid, methyl acrylic acid ester, oligoester acrylates of MGP-9 ((α,ω-methacryl(bistriethyleneglycol)phthalate)) or TGM-3 ((tri-(oxyethyleneglicol)-α,ω-dimethacrylate)) grades, the structuring of compositions, based on the DEG-1 aliphatic epoxy oligomer and U...

Unique structure and new thermophysical properties of poly(ethylene oxide) in nanocomposites based on nanoporous polypropylene matrices

Bakirov

J of Applied Polymer Sci

et al. 2022

Polypropylene (PP)−poly(ethylene oxide) (PEO) nanocomposites were prepared by tensile drawing of PP films in water–ethanol solutions containing PEO with molecular masses of 4, 20, and 200 kDa via environmental crazing (EC). EC of PP films is accompanied by the development of nanoporous structure, which is loaded with the PEO component. The content of PEO in the PP − PEO nanocomposites can achieve 40%. Crystallization of PEO within the nanoporous PP matrix proceeds under the conditions of the confined space: as a result, the degree of crystallinity and melting temperature of PEO are markedly reduced. This effect appears to be more pronounced as the molecular mass of PEO increases. The direction of orientation of the PEO crystalline lamellae also depends on the molecular mass of PEO. The prepared PP‐PEO composites with new thermophysical properties of PEO can be used as gas‐separation membranes as well as in microelectronics and electrochemical devices.