Effect of Ultrasound and Strain Rate on Tensile Behavior of Neat Thermoplastic Polyurethane Thin Films

2010 ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Test ◽  
Thermoplastic Polyurethane ◽  
Optical Element ◽  
Mechanical Tests ◽  
Primary Objective ◽  
Scanning Calorimetry ◽  
Rate Dependent

Thermoplastic Polyurethane (TPU) thin films have many applications in engineering and biomedical fields. Examples include moisture sensors, load cells, optical element and biocompatible stens. The TPU is a block copolymer naturally phase segregates into thermodynamically incompatible hard- and soft-segments. The size of the segments and their spatial distribution can significantly affect the microstructure and mechanical properties of the TPU. In this paper, we propose to investigate the effect of ultrasound energy on mechanical properties of TPU thin films fabricated via a solution route utilizing Tetra Hydro Furan (THF) as a solvent. The times of sonication was fixed at 60 minutes whilst all films were fabricated at average thickness of 20+/-5 um. The primary objective of the study was to understand the influence of ultrasound and strain rates on the material microstructure and the resulting mechanical properties. Mechanical tests have been conducted at two different displacement rates, namely 5 and 10 mm/min. Our preliminary results indicate that ultrasound improves the strength of the neat TPU films. We also see that strain hardening is displacement or strain rate dependent. We attribute these results to changes in the hard (H) and soft (S) domain structure. To further understand these microstructural variations, we propose to conduct Differential Scanning Calorimetry (DSC). The data has been interpreted in conjunction with our mechanical test data.

Effects of Ultrasound and Strain Rate on Tensile Mechanical Behavior of Thermoplastic Poly Urethane Thin Films

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Mechanical Test ◽  
Film Formation ◽  
Mechanical Tests ◽  
Scanning Calorimetry ◽  
Film Properties ◽  
Differential Scanning Calorimetry Scan ◽  
The Times ◽  
Specific Heat Capacities

Thermoplastic poly urethane (TPU) is a diblock copolymer which naturally phase segregates into thermodynamically incompatible hard (H) and soft (S) segments. The size of the segments and their spatial distribution can significantly affect the microstructure and mechanical properties of the material. In this paper, we investigated the effect of duration of exposure to ultrasound on the solution prior to film formation on the final film properties. The response variable for the study was primarily mechanical properties of the TPU thin films fabricated via a solution route utilizing tetra hydro furan as a solvent. The times of sonication were varied between 30 min and 90 min, while all films were fabricated at average thickness of 20 ± 5 μm. The mechanical tests have been conducted at two different displacement rates of 5 and 10 mm/min. Our results indicated that (relative to untreated TPU) ultrasound tends not to deteriorate the fracture strength, strain and yet improve the fracture toughness. We attribute these results to subtle events at the H and S segment/domain levels. To further understand these microstructural variations, we conducted differential scanning calorimetry scan tests between 25 °C and 200 °C at 5 °C/min on untested and tested TPU samples of all types. This data showed a delicate sonication time dependent trend and has been interpreted in conjunction with our mechanical test data. Transition temperatures, enthalpies, and specific heat capacities have been computed for these cases.

Effects of Steam Heat and Dry Heat Sterilization on Thermal and Mechanical Properties of Nylon and Policarbonate in Fabrication with Fused Filament

2021 ◽  
Vol 891 ◽  
pp. 150-163
Author(s):  
Jorge Mauricio Fuentes ◽  
Omar Flor Unda ◽  
Santiago Ferrandiz ◽  
Franyelit Suarez
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Analysis ◽  
Mechanical Tests ◽  
Effect Of Temperature ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Thermal Tests ◽  
Dry Heat ◽  
Izod Impact ◽  
Steam Heat

In this article presents evidence about performance of mechanical properties of polycarbonate and nylon materials, which are used in the additive manufacturing by deposition of molten material and that have been subjected to sterilization processes by moist heat at 121°C and dry heat at 140°C. This study provides useful information to consider the use of these materials in sanitary and sterile settings. Mechanical tests of tensile, flex, hardness, Izod impact, thermal tests in Differential Scanning Calorimetry DSC, Thermomechanical analysis TMA and Scanning Electron Microscopy SEM were performed. It is concluded that the mechanical and thermal properties have not been altered through the effect of temperature in sterilization processes.

Preparation of vinyl polymer/polyurethane hybrid latex particles and their application in nano-sized vinyl polymer particle/thermoplastic polyurethane blends

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Yanyan Wei ◽  
Chengzhong Zong ◽  
Fufang Wang
Keyword(s):  
Mechanical Properties ◽  
Thermoplastic Polyurethane ◽  
Polymer Particle ◽  
Gravimetric Analysis ◽  
Hybrid Particles ◽  
Scanning Calorimetry ◽  
Latex Particles ◽  
Vinyl Polymer ◽  
Hybrid Latex ◽  
Polyurethane Matrix

AbstractVinyl polymer/polyurethane hybrid latex particles with various compositions were successfully prepared via emulsion polymerization of vinyl monomer in the presence of self-emulsified polyurethane dispersion without using any surfactant. Studies were carried out on polymerization kinetics, characterization of the hybrid particles and the physical properties of nano-sized vinyl polymer particle/thermoplastic polyurethane blends. It was found that the maximum content of vinyl polymer in polyurethane hybrid particles was up to 80 percent and all of the vinyl polymer/polyurethane hybrid particles were less than 120 nm. Infrared spectroscopy, thermal gravimetric analysis and differential scanning calorimetry analysis indicated the influence of vinyl polymer on the polyurethane hybrid particles. With the polyurethane shells outside and, therefore, good compatibility with polyurethane matrix, the hybrid particles can be easily blended into polyurethane matrix. Some unusual changes of dynamic mechanical properties in the low temperature region were found in the blends of hybrid particles and thermoplastic polyurethane. With the addition of only 3%, the mechanical properties of these blends did not show a significant change. This study provided a new method to prepare hybrid particles in the absence of surfactant and made an attempt on application of vinyl polymer/polyurethane hybrid particles in the blending modification

scholarly journals Strain-Rate-Dependent Deformation Behavior and Mechanical Properties of a Multi-Phase Medium-Manganese Steel

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 344 ◽  
Author(s):  
Simon Sevsek ◽  
Christian Haase ◽  
Wolfgang Bleck
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Manganese Steel ◽  
Strain Rates ◽  
Rate Dependent ◽  
Medium Manganese Steel ◽  
Multi Phase

The strain-rate-dependent deformation behavior of an intercritically annealed X6MnAl12-3 medium-manganese steel was analyzed with respect to the mechanical properties, activation of deformation-induced martensitic phase transformation, and strain localization behavior. Intercritical annealing at 675 °C for 2 h led to an ultrafine-grained multi-phase microstructure with 45% of mostly equiaxed, recrystallized austenite and 55% ferrite or recovered, lamellar martensite. In-situ digital image correlation methods during tensile tests revealed strain localization behavior during the discontinuous elastic-plastic transition, which was due to the localization of strain in the softer austenite in the early stages of plastic deformation. The dependence of the macroscopic mechanical properties on the strain rate is due to the strain-rate sensitivity of the microscopic deformation behavior. On the one hand, the deformation-induced phase transformation of austenite to martensite showed a clear strain-rate dependency and was partially suppressed at very low and very high strain rates. On the other hand, the strain-rate-dependent relative strength of ferrite and martensite compared to austenite influenced the strain partitioning during plastic deformation, and subsequently, the work-hardening rate. As a result, the tested X6MnAl12-3 medium-manganese steel showed a negative strain-rate sensitivity at very low to medium strain rates and a positive strain-rate sensitivity at medium to high strain rates.

Processing and Characterization of Thermoplastic Polyurethane Nanocomposite Thin Films

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Optical Microscopy ◽  
Carbon Nanofiber ◽  
Droplet Diameter ◽  
Thermoplastic Polyurethane ◽  
Scanning Calorimetry ◽  
Ultrasound Assisted ◽  
Set Up

In this article, we have set up protocols for fabricating thermoplastic polyurethane thin films of about 30 μm (neat polyurethane and carbon nanofiber (CNF) containing polyurethane) via ultrasound assisted atomization at 20 kHz. From processing to thin film peel off, we have set up procedures for fabricating our samples. Using optical microscopy, we have examined the manufacturing of these films from a droplet diameter perspective. Our optical microscopy results indicate that the final film microstructure was directly dependent on the physical properties of the neat/CNF reinforced solution. Mechanical testing of these films was then carefully carried out using a dynamic mechanical analyzer (DMA) unit utilizing a specialized thin film test clamp fixture. These test results were compared with control cast films fabricated from the same solutions. For the similar extensions, we observed a drastic increase in the softness of the atomized film. We surmise that the ultrasound assisted droplet generation concurrent with secondary atomization and evaporation could have resulted in reduction of the molecular weight of the polyurethane in our atomized samples relative to the neat ones. Differential scanning calorimetry (DSC) scans have been conducted to confirm the changes in molecular weight. Although results were inconclusive there is evidence of exotherms at 49C in our atomized samples suggested of changes to molecular weight distribution.

Compression Moulding of Thermoplastic Nanocomposites Filled with MWCNT

2017 ◽  
Vol 25 (8) ◽  
pp. 611-620 ◽  
Author(s):  
Fabrizio Quadrini ◽  
Denise Bellisario ◽  
Loredana Santo ◽  
Felicia Stan ◽  
Fetecau Catalin
Keyword(s):  
Carbon Nanotubes ◽  
Differential Scanning Calorimetry ◽  
Filler Content ◽  
Thermoplastic Polyurethane ◽  
Mechanical Tests ◽  
Compression Moulding ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon-nanotubes (MWCNTs) were melt-mixed with three different thermoplastic matrices (polypropylene, PP, polycarbonate, PC, and thermoplastic polyurethane, TPU) to produce nanocomposites with three different filler contents (1, 3, and 5 wt.%). Initial nanocomposite blends (in the shape of pellets) were tested under differential scanning calorimetry to evaluate the effect of the melt mixing stage. Nanocomposite samples were produced by compression moulding in a laboratory-scale system, and were tested with quasi-static (bending, indentation), and dynamic mechanical tests as well as with friction tests. The results showed the effect of the filler content on the mechanical and functional properties of the nanocomposites. Compression moulding appeared to be a valuable solution to manufacture thermoplastic nanocomposites when injection moulding leads to loss of performance. MWCNT-filled thermoplastics could be used also for structural and functional uses despite, the present predominance of electrical applications.

Investigation of the Mechanical Properties of Thin Films by Bulge Test

2009 ◽  
Vol 156-158 ◽  
pp. 477-482
Author(s):  
Audrey Hémel ◽  
Alain Jacques ◽  
Thomas Schenk ◽  
Tomáš Kruml
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Mechanical Tests ◽  
Bulge Test ◽  
Gold Films ◽  
Test Device

A new bulge test device has been built, with the aim to perform mechanical tests on membranes with a thickness in the 100 nm to 10 µm range, between room temperature and 900°C. The first tests on Si3N4 and gold films give results consistent with literature data.

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