Influence of wax content on the electrical, thermal and tribological behaviour of a polyamide 6/graphite composite

2016 ◽  
Vol 36 (3) ◽  
pp. 279-286
Author(s):  
Huseyin Unal ◽  
Ugur A. Kaya ◽  
Kadir Esmer ◽  
A. Mimaroglu ◽  
Bayram Poyraz
Keyword(s):  
Composite Materials ◽  
Friction Coefficient ◽  
Polyamide 6 ◽  
Electrical Performance ◽  
Tribological Behaviour ◽  
Scanning Calorimetry ◽  
Graphite Composite ◽  
Wear Rates ◽  
Melting Temperatures ◽  
Wax Content

Abstract In this study, the influence of wax content on the electrical, thermal and tribological properties of a polyamide 6 composite filled with 15% wt. graphite was investigated. The wax filler contents of the composite were by 2, 4 and 6 wt.%. Characterisation of the composites was obtained using a Fourier transform infrared spectroscopy test. Electrical performance tests were carried out, and the dielectric real values (ε′) and imaginary values (ε″) were recorded. Thermal differential scanning calorimetry tests were carried out, and the glassy and melting temperatures of the composite materials were recorded. Furthermore, tribological tests were carried out and the friction coefficient and wear rate of the composites were recorded. The results show that the increase in wax content led to the increase in the permittivity values (ε′ and ε″) of the composites. The increase in wax content also led to the decrease in the friction coefficient and wear rates of the composite materials. Furthermore, the glassy and melting temperatures of the composite materials showed a sensitivity to the wax content. Finally, it is concluded that optimum properties, in total, were obtained in the composite filled with 6 wt.% wax.

Tribological performance of self-lubricated polyamide6/boric oxide composites after water conditioning

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kawaljit Singh Randhawa ◽  
Ashwin Patel
Keyword(s):  
Friction Coefficient ◽  
Abrasion Resistance ◽  
Tribological Performance ◽  
Boric Oxide ◽  
Resistance Testing ◽  
Tribological Behaviour ◽  
Content Type ◽  
Wear Rates ◽  
Water Conditioning ◽  
Oxide Composites

Purpose This paper aims to investigate the tribological performance, i.e. abrasion resistance, friction coefficient and wear rates, of self-lubricated water conditioned polyamide6/boric oxide composites. Design/methodology/approach Polyamide6 and polyamide6/boric oxide self-lubricated composites were immersed in water for 15 days to analyze the effect of water conditioning on friction, wear and abrasion resistance. Tribological testing on pin-on-disc tribometer and abrasion resistance testing on TABER abrader were performed to see the friction coefficient and wear rates of materials. The scanning electron microscopy (SEM) characterizations were performed to analyze the wear tracks. Findings Tribological testing results revealed the loss in abrasive resistance, but there was an improvement in frictional coefficient and wear rates with steel after water absorption. The SEM images clearly show less depth of wear tracks in water-conditioned materials than dry ones. Water conditioning was found supportive in the formation of smooth lubricating transfer film on steel disc during the tribological testing. Originality/value The tribological behaviour of polymer composites is different in dry and in high humidity or water conditions. Experiments were performed to investigate B2O3 solid lubricant filler effectiveness on tribological behaviour of water-conditioned polyamide composites. Bonding between polyamide6 and water molecules plus the formation of orthoboric acid was found advantageous in decreasing the friction coefficient and wear rates of composites.

scholarly journals Effects of Alkyl-Substituted Polybenzoxazines on Tribological Properties of Non-Asbestos Composite Friction Materials

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 567
Author(s):  
Anun Wongpayakyotin ◽  
Chanchira Jubsilp ◽  
Sunan Tiptipakorn ◽  
Phattarin Mora ◽  
Christopher W. Bielawski ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Composite Materials ◽  
Coefficient Of Friction ◽  
Aromatic Amines ◽  
Underlying Structure ◽  
Methyl Groups ◽  
Friction Materials ◽  
Wear Rates ◽  
Structure Properties ◽  
Crosslink Densities

A series of substituted polybenzoxazines was synthesized and studied as binders in non-asbestos friction composite materials. The structures of the polybenzoxazines were varied in a systemic fashion by increasing the number and position of pendant alkyl (methyl) groups and was accomplished using the respective aromatic amines during the polymer synthesis step. By investigating the key thermomechanical and tribological characteristics displayed by the composite materials, the underlying structure-properties relationships were deconvoluted. Composite friction materials with higher thermomechanical and wear resistance properties were obtained from polybenzoxazines with relatively high crosslink densities. In contrast, polybenzoxazines with relatively low crosslink densities afforded composite friction materials with an improved coefficient of friction values and specific wear rates.

Probing Three Distinct Crystal Polymorphs of Melt-Crystallized Polyamide 6 by an Integrated Fast Scanning Calorimetry Chip System

2021 ◽  
Author(s):  
Xiaoshi Zhang ◽  
Anne Gohn ◽  
Gamini Mendis ◽  
John F. Buzinkai ◽  
Steven J. Weigand ◽  
...  
Keyword(s):  
Polyamide 6 ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry

scholarly journals Chemistry of collagen cross-links: glucose-mediated covalent cross-linking of type-IV collagen in lens capsules

1993 ◽  
Vol 296 (2) ◽  
pp. 489-496 ◽  
Author(s):  
A J Bailey ◽  
T J Sims ◽  
N C Avery ◽  
C A Miles
Keyword(s):  
Type Iv Collagen ◽  
Cross Linking ◽  
Mechanical And Thermal Properties ◽  
Maximum Strain ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Type Iv ◽  
Collagen Molecules ◽  
Cross Links

The incubation of lens capsules with glucose in vitro resulted in changes in the mechanical and thermal properties of type-IV collagen consistent with increased cross-linking. Differential scanning calorimetry (d.s.c.) of fresh lens capsules showed two major peaks at melting temperatures Tm 1 and Tm 2 at approx. 54 degrees C and 90 degrees C, which can be attributed to the denaturation of the triple helix and 7S domains respectively. Glycosylation of lens capsules in vitro for 24 weeks caused an increase in Tm 1 from 54 degrees C to 61 degrees C, while non-glycosylated, control incubated capsules increased to a Tm 1 of 57 degrees C. The higher temperature required to denature the type-IV collagen after incubation in vitro suggested increased intermolecular cross-linking. Glycosylated lens capsules were more brittle than fresh samples, breaking at a maximum strain of 36.8 +/- 1.8% compared with 75.6 +/- 6.3% for the fresh samples. The stress at maximum strain (or ‘strength’) was dramatically reduced from 12.0 to 4.7 N.mm.mg-1 after glycosylation in vitro. The increased constraints within the system leading to loss of strength and increased brittleness suggested not only the presence of more cross-links but a difference in the location of these cross-links compared with the natural lysyl-aldehyde-derived cross-links. The chemical nature of the fluorescent glucose-derived cross-link following glycosylation was determined as pentosidine, at a concentration of 1 pentosidine molecule per 600 collagen molecules after 24 weeks incubation. Pentosidine was also determined in the lens capsules obtained from uncontrolled diabetics at a level of about 1 per 100 collagen molecules. The concentration of these pentosidine cross-links is far too small to account for the observed changes in the thermal and mechanical properties following incubation in vitro, clearly indicating that another as yet undefined, but apparently more important cross-linking mechanism mediated by glucose is taking place.

Melting and Oxidation of Nanometer Size Aluminum Powders

2005 ◽  
Vol 896 ◽  
Author(s):  
Mikhaylo A Trunov ◽  
Swati Umbrakar ◽  
Mirko Schoenitz ◽  
Joseph T Mang ◽  
Edward L Dreizin
Keyword(s):  
Particle Size ◽  
Oxidation Behavior ◽  
Melting Behavior ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Scanning Calorimetry ◽  
Aluminum Powders ◽  
Melting Temperatures ◽  
X Ray Scattering ◽  
Powder Samples

AbstractRecently, nanometer-sized aluminum powders became available commercially and their use as potential additives to propellants, explosives, and pyrotechnics has attracted significant interest. It has been suggested that very low melting temperatures are expected for nano-sized aluminum powders and that such low melting temperatures could accelerate oxidation and trigger ignition much earlier than for regular, micron-sized aluminum powders. The objective of this work was to investigate experimentally the melting and oxidation behavior of nano-sized aluminum powders. Powder samples with three different nominal sizes of 44, 80, and 121 nm were provided by Nanotechnologies Inc. The particle size distributions were measured using small angle x-ray scattering. Melting was studied by differential scanning calorimetry where the powders were heated from room temperature to 750 °C in argon environment. Thermogravimetric analysis was used to measure the mass increase indicative of oxidation while the powders were heated in an oxygen-argon gas mixture. The measured melting curves were compared to those computed using the experimental particle size distributions and thermodynamic models describing the melting temperature and enthalpy as functions of the particle size. The melting behavior predicted by different models correlated with the experimental observations only qualitatively. Characteristic step-wise oxidation was observed for all studied nanopowders. The observed oxidation behavior was well interpreted considering the recently established kinetics of oxidation of micron-sized aluminum powders. No correlation was found between the melting and oxidation of aluminum nanopowders.

Microstructural Features and Properties of Al-Cu-Mg Alloy Containing Silver and Cerium

2021 ◽  
Vol 316 ◽  
pp. 533-537
Author(s):  
Pavel L. Reznik ◽  
Boris V. Ovsyannikov
Keyword(s):  
Heat Treatment ◽  
Mechanical Characteristics ◽  
Dendritic Segregation ◽  
Scanning Calorimetry ◽  
Electron Probe Micro Analyzer ◽  
Melting Temperatures ◽  
Heat Treatment Mode ◽  
Cast Condition ◽  
Component Phase ◽  
Non Equilibrium

The article presents the results of an investigation of microstructural features and mechanical characteristics of Al-5.0Cu-0.5Mg alloy containing up to 0.4 wt. % Ag and up to 0.1 wt. % Ce. The experiment was conducted using optical microscopy, Scanning Electron Microscopy as well as an electron probe micro-analyzer and Differential Scanning Calorimetry. Samples in cast condition and after heat treatment were examined. The melting temperatures of non-equilibrium eutectics (non-equilibrium solidus), equilibrium solidus and liquidus were determined. The optimal temperature of the homogenizing heat treatment was determined, which was 500°C. Using this heat treatment mode resulted in the elimination of dendritic segregation and complete dissolution of silver in aluminum. Injection of cerium into the Al-Cu-Mg-Ag system during crystallization of the melt is accompanied by the formation of a coarse four-component phase, which has the morphology of polyhedrons, is on the grain boundaries. The estimation of the relation between microstructure characteristics and mechanical properties of the alloy has been made.

Development of Porous Films Based on Polyanionic Cellulose to Form Functional Coatings

2022 ◽  
Vol 1049 ◽  
pp. 130-137
Author(s):  
Natalia Antonova
Keyword(s):  
Friction Coefficient ◽  
Thermal Destruction ◽  
Solid Lubricant ◽  
Steel Sample ◽  
Porous Coating ◽  
Surface Porosity ◽  
Functional Coatings ◽  
Porous Films ◽  
Scanning Calorimetry ◽  
Antifriction Coatings

New porous films based on polyanionic cellulose with AlOOH nanoparticles have been developed. The morphology of the films has been studied by electron microscopy: the size of the formed pores is 1000-500 microns; the total surface porosity of the films is 30%. Using infrared microscopy, it was shown that during the formation of porous films, their chemical composition remains unchanged. Differential scanning calorimetry was used to determine the threshold for thermal destruction of porous films: 306 С. The possibility of using the obtained materials as antifriction coatings when filling the pores with solid lubricant MoS2 is considered. It is shown that for a steel sample protected by a porous coating with MoS2, the friction coefficient decreases by 50% compared to the friction coefficient for a steel surface under a load of up to 450 MPa.

DEVELOPMENT AND RESEARCH OF POLYURETHANE FOAM COMPOSITE MATERIALS WITH LYSOZYME

2021 ◽  
Vol 43 (3) ◽  
pp. 204-213
Author(s):  
T.V. VISLOHUZOVA ◽  
◽  
R.A. ROZHNOVA ◽  
N.A. GALATENKO ◽  
◽  
...  
Keyword(s):  
Glass Transition ◽  
Composite Materials ◽  
Polyurethane Foam ◽  
Single Phase ◽  
Mechanical Tests ◽  
Polyurethane Foams ◽  
Scanning Calorimetry ◽  
Heating Capacity ◽  
Foam Composite ◽  
Treatment Of Wounds

The article is devoted to the development and research of the structure and properties of polyurethane foam (PUF) composite materials with the antibacterial enzyme lysozyme. A series of PUF composite materials with lysozyme of various concentrations (1, 3 and 5 wt %) were obtained. It is established that the immobilization of lysozyme occurs due to intermolecular hydrogen bonds by the method of IR spectroscopy. According to the results of physical-mechanical tests the adhesive strength of polyurethane foam compositions with lysozyme is in the range of 0,82–1,16 MPa. The introduction of lysozyme into the composition of polyurethane foams and an increase its amount causes a decrease in the values of adhesion strength by 18,1–29,3 %. According to differential scanning calorimetry the tested systems are single-phase with a glass transition temperature in the range of -49,20 to -49,86 °C. The introduction of lysozyme into the composition causes an increase heating capacity at the glass transition, which can be associated with a decrease of the packing density of macrochains resulting in an increase in free volume, which leads to an increase molecular mobility. According to the results of the analysis of transmission optical microscopy micrographs the studied PUF have a microporous structure, which depends on the content of filler in their composition. It was found that the presence of lysozyme in the composition of composite materials leads to a decrease in the percentage of porosity, an increase in the number of pores with a diameter of up to 300 μm, which is 76,7–82,4 % (while for PUF – 69,5 %) and the absence of pores with a diameter larger than 990 μm. Thermogravimetric characteristics indicate the heat resistance of the synthesized PUF to a temperature of 179,95 °C, which allows dry sterilization of samples without changing their characteristics. PUF composite materials with lysozyme are promising materials that can be used in medical practice as polymer compositions for the treatment of wounds and burns.

Sign in / Sign up

Export Citation Format

Share Document