scholarly journals Influence of Solid Lubricants on the Tribological Performance of Photocurable Resins for Vat Photopolymerization

Lubricants ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 104
Author(s):  
Janez Slapnik ◽  
Tanja Stiller ◽  
Thomas Wilhelm ◽  
Andreas Hausberger
Keyword(s):  
Power Transmission ◽  
Charpy Impact ◽  
Solid Lubricants ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Tribological Performance ◽  
Urethane Acrylate ◽  
Mechanical And Thermal Properties ◽  
Digital Light Processing ◽  
3D Printed

New developments in additive manufacturing (AM) are enabling the use of 3D printed parts in increasingly demanding applications, such as in mechanical power transmission systems, where excellent build quality and tribological performance are required. The tribological properties of thermoplastic-based AM technologies are well knowninject, whereas the performance of photopolymer-based AM technologies is very rarely explored. This study aims to provide new insight into the tribological performance of 3D printed parts produced using vat photopolymerization (VPP). Photocurable resins based on aliphatic urethane acrylate oligomers were modified with different solid lubricants (polytetrafluoroethylene (PTFE), graphite and molybdenum disulfide (MoS2)) and 3D printed using Digital Light Processing (DLP). The mechanical and thermal properties were studied using the tensile tests, Charpy impact tests, Shore D, and dynamic mechanical analysis (DMA). The tribological performance was studied using a Pin-on-Disk tribometer. Among the lubricants, PTFE had the highest impact on the coefficient of friction (µ) and the specific wear rate (ws). The hybrid lubricant system (PTFE/MoS2) resulted in excellent tribological performance, where the µ was reduced by up to 52% and ws by up to 92%.

scholarly journals Mechanical and Thermal Properties of Polyether Polytriazole Elastomers Formed by Click-Chemical Reaction Curing Glycidyl Azide Polymer

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1988 ◽  
Author(s):  
Liming He ◽  
Jun Zhou ◽  
Yutao Wang ◽  
Zhongliang Ma ◽  
Chunlin Chen
Keyword(s):  
Click Reaction ◽  
Hot Spot ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Random Copolymers ◽  
Mechanical And Thermal Properties ◽  
Glycidyl Azide Polymer ◽  
Ordered Structures ◽  
The Cross ◽  
Glycidyl Azide

Energetic binders are a research hot-spot, and much emphasis has been placed on their mechanical properties. In this study, propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PTPET) was synthesized. Then, PTPET and low-molecular-weight ester-terminated glycidyl azide polymer (GAP) were reacted by the click reaction without using catalysts to obtain a polyether polytriazole elastomer. Through tensile tests, where R = 0.5, the tensile strength reached 0.332 MPa, with an elongation at break of 897.1%. Swelling tests were used to measure the cross-linked network and showed that the cross-linked network regularity was reduced as R increased. The same conclusions were confirmed by dynamic mechanical analysis (DMA). In DMA curves, Tg was around −70 to −65 °C, and a small amount of crystallization appeared at between −50 and −30 °C, because locally ordered structures were also present in random copolymers, thereby forming localized crystals. Their thermal performance was tested by Differential Scanning Calorimeter (DSC) and Thermal Gravimetric Analyzer (TG), and the main mass loss occurred at around 350 to 450 °C, which meant that they were stable. In conclusion, the polyether polytriazole elastomer can be used as a binder in a composite propellant.

scholarly journals Characterization of Polypropylene Modified by Blending Elastomer and Nano-Silica

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1321 ◽  
Author(s):  
Xiaohong Chi ◽  
Lu Cheng ◽  
Wenfeng Liu ◽  
Xiaohong Zhang ◽  
Shengtao Li
Keyword(s):  
Dielectric Properties ◽  
Space Charge ◽  
Power Transmission ◽  
Breakdown Strength ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Insulation Material ◽  
Nano Silica ◽  
Scanning Calorimetry ◽  
High Voltage Direct Current

Polypropylene (PP) contains promising application prospects in thermoplastic cables for high voltage direct current (HVDC) power transmission because of its outstanding thermal and dielectric properties. However, the problem of poor toughness and space charge has restricted the application of pure PP in HVDC cables. In this paper, polyolefin elastomer (POE) and nano-silica were blended thoroughly and added into a PP mixture by a melting method. Scanning electron microscopy (SEM) was employed to observe the dispersion of POE and nanoparticles. Thermal properties were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Mechanical properties were evaluated by tensile tests. The elastomeric properties of composites were improved as the dispersed POE could transfer and homogenize external mechanical forces. DC breakdown results showed that the fail strength of composite with 10 phr POE and 1 phr nano-silica was obviously enhanced. The pulsed electro-acoustic (PEA) results showed that the injection and accumulation of space charge was increased by the introduction of POE, while it was restrained by the collective effect caused by nano-silica filling. X-ray diffraction (XRD) spectrograms showed that secondary ordered structures existed in the composites of PP, POE, and nano-silica, and that the ordered structure around the nanoparticles contributed to the enhancement of breakdown strength. The mechanical and dielectric properties were modified synergistically, which made the modified PP a propitious insulation material for HVDC cables.

scholarly journals Tough Materials Through Ionic Interactions

2021 ◽  
Vol 9 ◽  
Author(s):  
Linda Salminen ◽  
Erno Karjalainen ◽  
Vladimir Aseyev ◽  
Heikki Tenhu
Keyword(s):  
Thermal Properties ◽  
Ion Pairs ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Polymer Materials ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Shape Stability ◽  
Chemical Crosslinks ◽  
Unique Approach

This article introduces butyl acrylate-based materials that are toughened with dynamic crosslinkers. These dynamic crosslinkers are salts where both the anion and cation polymerize. The ion pairs between the polymerized anions and cations form dynamic crosslinks that break and reform under deformation. Chemical crosslinker was used to bring shape stability. The extent of dynamic and chemical crosslinking was related to the mechanical and thermal properties of the materials. Furthermore, the dependence of the material properties on different dynamic crosslinkers—tributyl-(4-vinylbenzyl)ammonium sulfopropyl acrylate (C4ASA) and trihexyl-(4-vinylbenzyl)ammonium sulfopropyl acrylate (C6ASA)—was studied. The materials’ mechanical and thermal properties were characterized by means of tensile tests, dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. The dynamic crosslinks strengthened the materials considerably. Chemical crosslinks decreased the elasticity of the materials but did not significantly affect their strength. Comparison of the two ionic crosslinkers revealed that changing the crosslinker from C4ASA to C6ASA results in more elastic, but slightly weaker materials. In conclusion, dynamic crosslinks provide substantial enhancement of mechanical properties of the materials. This is a unique approach that is utilizable for a wide variety of polymer materials.

Influence of WS2/SnS2 on the tribological performance of copper-free brake pads

2019 ◽  
Vol 71 (3) ◽  
pp. 398-405 ◽  
Author(s):  
Justin Antonyraj I. ◽  
Vijay R. ◽  
Lenin Singaravelu D.
Keyword(s):  
Thermal Stability ◽  
Profile Analysis ◽  
Film Formation ◽  
Three Dimensional ◽  
Solid Lubricants ◽  
Tribological Performance ◽  
Mechanical And Thermal Properties ◽  
Content Type ◽  
Brake Pads ◽  
Lubrication Film

Purpose The purpose of this study is to investigate the influence of solid lubricants (tungsten disulfide [WS2]/ Tin disulfide [SnS2]) on the tribological performance of brake pads. Design/methodology/approach In this study, the brake pads were developed by varying the solid lubricants (WS2/SnS2) without varying the other ingredients. The brake pads were developed as per the industrial procedure. Thermal stability was found for varying ingredients and developed pads. The physical, mechanical and thermal properties of the developed brake pads were analyzed as per the industrial standards. The tribological properties were analyzed using the Chase test. The worn surface analysis was done using scanning electron microscopy, elemental mapping and three-dimensional profile analysis. Findings The experimental results indicate that the WS2-based brake pads possess good physical, chemical and mechanical properties with stable friction and less wear rate due to its good lubrication film formation and thermal stability natures of WS2. Originality/value This paper explains the effect of solid lubricants in brake pads for enhancing the tribological performance by the shearing of crystal structure, thermal stability and tribo film properties of the lubricants.

scholarly journals Effect of a Small Amount of Thermoplastic Starch Blend on the Mechanical Recycling of Conventional Plastics

2020 ◽  
Author(s):  
Dan Åkesson ◽  
Gauthaman Kuzhanthaivelu ◽  
Martin Bohlén
Keyword(s):  
High Density Polyethylene ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Thermoplastic Starch ◽  
Mechanical And Thermal Properties ◽  
Waste Streams ◽  
Strong Reduction ◽  
Mechanical Recycling ◽  
Scanning Calorimetry ◽  
Elongation At Break

Abstract The usage of bioplastics could increase in the future which may cause contamination of the waste streams of conventional plastics. The objective of this study was to investigate if a small amount of biopolymer contaminating conventional polymers would significantly affect mechanical and thermal properties. A starch-based plastic was first compounded by blending plasticised starch with PLA (polylactic acid). This polymer blend was subsequently compounded with HDPE (high density polyethylene), PP (polypropylene) or PET (polyethylene terephthalate) at 0%, 1% and 5% of the biopolymer. The compounds were characterised by tensile tests, Charpy impact tests, DSC (differential scanning calorimetry) and FESEM (field emission scanning electron microscopy). Tests showed that PE and PP were not significantly affected in terms of tensile strength and modulus but the elongation at break showed a strong reduction. PET was, on the other hand, incompatible with the starch-based plastic. Already at 1% contamination, PET had lost most of its impact strength.

Characterization of PLA/TPU composite filaments manufactured for 3D printing with FDM

2021 ◽  
pp. 089270572110625
Author(s):  
Ajay Jayswal ◽  
Sabit Adanur
Keyword(s):  
3D Printing ◽  
Fused Deposition Modeling ◽  
Thermoplastic Polyurethane ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Uniaxial Tensile ◽  
Scanning Calorimetry ◽  
Fused Deposition ◽  
3D Printed

Polylactic acid (PLA) and thermoplastic polyurethane (TPU) were mixed in different proportions and extruded through twin-screw and single-screw extruders to obtain composite filaments to be used for 3D printing with fused deposition modeling (FDM) method. The properties of the filaments were characterized using uniaxial tensile tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), rheology, polarized optical microscope (POM), and scanning electron microscope (SEM). 3D printed samples from composite filaments were tested using dynamic mechanical analysis (DMA). It was found that the tensile strength and modulus of the filaments decrease while elongation at break increases with the increasing TPU content in the composite. The analysis also showed a partial miscibility of the polymer constituents in the solution of composite filaments. Finally, a flexible structure, plain weave fabric, was designed and 3D printed using the composite filaments developed which proved that the filaments are well suited for 3D printing.

scholarly journals MODIFIED POLYLACTIDE FILAMENTS FOR 3D PRINTING WITH IMPROVED MECHANICAL PROPERTIES

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Janez Slapnik ◽  
Rajko Bobovnik ◽  
Maja Mešl ◽  
Silvester Bolka
Keyword(s):  
Thermal Properties ◽  
3D Printing ◽  
Impact Strength ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Core Shell ◽  
Mechanical And Thermal Properties ◽  
3D Printed ◽  
Injection Molded ◽  
Charpy Impact Strength

We investigated the effects of two different types of impact modifiers, i.e. core-shell rubber and aliphatic polyester, on the mechanical and thermal properties of polylactide (PLA) filaments for 3D printing. First, PLA/impact modifier blends with various concentrations of impact modifiers were prepared by melt blending in a co-rotating twin screw extruder and test specimens by injection molding. The mechanical and thermal properties of blends were investigated by tensile and bending tests, dynamic mechanical analysis (DMA) and Charpy impact test. It was found that core-shell rubber remarkably improved Charpy impact strength at loadings above 5 wt % (up to 746 %). As shown by DMA, the PLA/10 wt % core-shell rubber blend exhibited better damping performance as compared to neat PLA over the whole examined frequency range, especially at high frequencies, which explained the increase in impact strength. The filament for a fused deposition modeling (FDM), 3D printer was prepared from blend with the highest impact strength (PLA/10 wt % core-shell rubber), whereas PLA and acrylonitrile-butadiene-styrene copolymer (ABS) filaments were used for reference. Test specimens were prepared by using a consumer FDM 3D printer. The mechanical and thermal properties were investigated by tensile and bending tests, DMA, Charpy impact test, and ultra-fast differential scanning calorimetry (Flash DSC). Specimens from PLA blend exhibited 109 % increase in Charpy impact strength as compared to neat PLA. In contrast to injection molded specimens, 3D printed PLA blend exhibited higher tensile E modulus than neat PLA, which was ascribed to improved interlayer adhesion. Moreover, DMA and Flash DSC analysis of 3D printed specimens showed an increase in the glass transition temperature as compared to injection molded specimens. This phenomenon was ascribed to reduction of free volume because of slow cooling in 3D printing process, which is also the reason for increased tensile E modulus of the PLA blend. All tested PLA, PLA blend and ABS filaments were in amorphous state as shown by Flash DSC analysis. Bending test showed an increased toughness of PLA blend in comparison to neat PLA and also higher toughness as compared to ABS. The modified polylactide (PLA/10 wt % core-shell rubber) filament thus combines easy processability of PLA filament and impact toughness of ABS filament.

scholarly journals Biodegradable Poly(ester) Urethane Acrylate Resins for Digital Light Processing: From Polymer Synthesis to 3D Printed Tissue Engineering Constructs

2020 ◽  
Author(s):  
Matthew Baker ◽  
Rong Wang ◽  
Febriyani Damanik ◽  
Tobias Kuhnt ◽  
Hans Ippel ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Molecular Weight ◽  
Dermal Fibroblasts ◽  
Surface Topology ◽  
Urethane Acrylate ◽  
Complex Structures ◽  
Human Dermal Fibroblasts ◽  
Digital Light Processing ◽  
Biodegradable Poly ◽  
3D Printed

<div>Digital light processing (DLP) is one of the most accurate and fastest additive manufacturing</div><div>technologies to produce a variety of products, from patient-customized biomedical implants to</div><div>consumer goods; however, DLP’s use in tissue engineering is limited largely due to a lack of</div><div>biodegradable resins. Herein, a library of biodegradable urethane acrylate-capped poly(esters)</div><div>(with variations in molecular weight) is investigated as the basis for a DLP printable ink for</div><div>tissue engineering. The synthesized oligomers show good printability in a DLP resin, capable</div><div>of creating complex structures with mechanical properties matching those of medium-soft</div><div>tissues (1–3 MPa). While fabricated films from different molecular weight resins showed few</div><div>differences in surface topology, wettability, and protein adsorption, the adhesion and metabolic</div><div>activity of L929 and human dermal fibroblasts (HDFs) were significantly different: resins from</div><div>higher molecular weight oligomers provided greater cell adhesion and metabolic activity. These</div><div>printable and biodegradable resins show the importance of oligomer molecular weight on</div><div>scaffold properties, and facilitate the printing of elastomeric customizable scaffolds for a variety</div><div>of tissue engineering applications.</div>

scholarly journals Biodegradable Poly(ester) Urethane Acrylate Resins for Digital Light Processing: From Polymer Synthesis to 3D Printed Tissue Engineering Constructs

2020 ◽  
Author(s):  
Matthew Baker ◽  
Rong Wang ◽  
Febriyani Damanik ◽  
Tobias Kuhnt ◽  
Hans Ippel ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Molecular Weight ◽  
Dermal Fibroblasts ◽  
Surface Topology ◽  
Urethane Acrylate ◽  
Complex Structures ◽  
Human Dermal Fibroblasts ◽  
Digital Light Processing ◽  
Biodegradable Poly ◽  
3D Printed

<div>Digital light processing (DLP) is one of the most accurate and fastest additive manufacturing</div><div>technologies to produce a variety of products, from patient-customized biomedical implants to</div><div>consumer goods; however, DLP’s use in tissue engineering is limited largely due to a lack of</div><div>biodegradable resins. Herein, a library of biodegradable urethane acrylate-capped poly(esters)</div><div>(with variations in molecular weight) is investigated as the basis for a DLP printable ink for</div><div>tissue engineering. The synthesized oligomers show good printability in a DLP resin, capable</div><div>of creating complex structures with mechanical properties matching those of medium-soft</div><div>tissues (1–3 MPa). While fabricated films from different molecular weight resins showed few</div><div>differences in surface topology, wettability, and protein adsorption, the adhesion and metabolic</div><div>activity of L929 and human dermal fibroblasts (HDFs) were significantly different: resins from</div><div>higher molecular weight oligomers provided greater cell adhesion and metabolic activity. These</div><div>printable and biodegradable resins show the importance of oligomer molecular weight on</div><div>scaffold properties, and facilitate the printing of elastomeric customizable scaffolds for a variety</div><div>of tissue engineering applications.</div>

scholarly journals APPLICATION OF DYNAMIC MECHANICAL ANALYSIS FOR UV-CURED COATINGS

2020 ◽  
Vol 2 (2) ◽  
pp. 55-59
Author(s):  
Shakeeba Jalali
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Cross Linking ◽  
Urethane Acrylate ◽  
Mechanical And Thermal Properties ◽  
Epoxy Ester ◽  
Uv Curable ◽  
Dynamic Mechanical ◽  
Reactive Diluents ◽  
End Group

The present study is about soya epoxy ester which was made by epoxy resin and fatty acid. Oleochemical polyols were prepared after the soya epoxy ester reacted with various hydroxyl and cellulose based derivatives. These oleochemical polyols were changed to urethanes prepolymers by reacting NCO groups of TDI and IPDI.  By utilizing the reaction of NCO end group of urethane with HEMA, these urethanes were transformed in to urethane acrylate oligomer. By mixing the oligomers with various reactive diluents, UV curable coating compositions were derived. The methodology was based on dynamic mechanical analysis. The UV cured samples from cellulose based oleochemical polyols exhibit good mechanical and thermal properties. Their mechanical properties are more dependent on double bonds from unsaturated contribute to curing with extra cross-linking by an oxidative mechanism.

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