Dynamic Mechanical Analysis Method Research Articles

Damping properties of Sn58Bi and Sn3.0Ag0.5Cu solders with different thicknesses and preparation directions

PurposeThis study aims to experimentally assess the effect of thickness and preparation direction on the damping properties of Sn58Bi and Sn3.0Ag0.5Cu solders.Design/methodology/approachSn58Bi and Sn3.0Ag0.5Cu solder strips with different thicknesses were prepared from the bulk in longitudinal and horizontal directions, and the ratio of loss modulus and storage modulus of the samples was measured by the dynamic mechanical analysis method as the index of damping properties.FindingsSn58Bi and Sn3.0Ag0.5Cu solders exhibited viscoelastic relaxation, and their damping properties decreased with decreasing thickness. The damping properties of both solders had no obvious difference in longitudinal and horizontal directions. Sn58Bi has a more obvious high-temperature damping background than Sn3.0Ag0.5Cu solder. In addition, compared with Sn58Bi solder, Sn3.0Ag0.5Cu solder had an obvious internal friction peak, which moved toward high temperature with increasing frequency. The activation energies of Sn58Bi solder with a thickness of 0.5 mm at the longitudinal and horizontal directions were 0.84 and 0.67 eV, respectively, which were 0.39 and 0.53 eV, respectively, for the Sn3.0Ag0.5Cu solder.Originality/valueThe damping properties of Sn58Bi and Sn3.0Ag0.5Cu solder decreased with decreasing thickness, while their damping properties changed insignificantly when they were prepared from different directions. The internal friction peak of Sn3.0Ag0.5Cu solder moved to higher temperatures with increasing frequency.

In-situ reaction compatibilization modification of poly(butylene succinate-co-terephthalate)/polylactide acid blend films by multifunctional epoxy compound

Poly(butylene succinate-co-terephthalate) (PBST) copolyester, is a new type of biodegradable synthetic polymer material that has emerged in recent years, but it cannot meet the market requirements, because of its low strength. The high-strength and high-modulus polylactic acid (PLA) was blended with PBST to increase its strength, and the chain extender ADR-4370 was used to modify PBST/PLA films by reaction and compatibilization. Compared with the 80/20 wt% PBST/PLA films, the tensile strength after modification with 0.3 wt% ADR was increased by 21.8 % and 44.3 % in the machine direction (MD) and in the transverse direction (TD), respectively. The Water Vapor Permeability (WVP) was decreased from 10.0 × 10−14 to 3.09 × 10−14 g·cm/cm2·s·Pa. The compatibilization mechanism was studied by gel permeation chromatography, infrared spectroscopy, dynamic mechanical analysis, rheological analysis, and other characterization methods. The formation of the copolymer PLA-g-PBST is the most important factor to improve the compatibility of the system and the mechanical properties of the films.

Evaluation of the High- and Low-Temperature Performance of Asphalt Mortar Based on the DMA Method

Asphalt mortar is a typical temperature-sensitive material that plays a crucial role in the performance of asphalt mixture. This study evaluates the high- and low-temperature performance of asphalt mortar based on the dynamic mechanical analysis (DMA) method. Temperature-sweep tests of asphalt mortars were conducted using the DMA method under fixed strain level, frequency, and heating rate conditions. The dynamic mechanical response curves, characteristic temperature, and other indices were obtained and used to investigate the high- and low-temperature performance of asphalt mortar. The results showed that the phase transition temperatures T1, T0, and Tg can be used to evaluate the low-temperature performance of asphalt mortar. Additionally, they had a good linear relationship, and the evaluation results were consistent. Meanwhile, T2, E60, and tan(δ)max indicators can effectively evaluate the high-temperature performance of asphalt mortar. Asphalt plays a key role in the performance of asphalt mortar. Mortars with neat asphalt A70 and modified asphalt AR had the worst and best high- and low-temperature performances, respectively. Furthermore, the finer gradation improved the low-temperature performance of asphalt mortar, while the coarser gradation improved the high-temperature properties of modified asphalt mortars but had the opposite effect on neat asphalt A70.

The Effect of Agglomeration on the Electrical and Mechanical Properties of Polymer Matrix Nanocomposites Reinforced with Carbon Nanotubes.

In this work, we investigated the effect of carbon nanotubes addition and agglomeration formation on the mechanical and electrical properties of CNT–polymer-based nanocomposites. Six specimens with carbon nanotubes (CNTs) fractions of 0%, 0.5%, 1%, 2%, 4% and 5% were manufactured and characterized by dynamic mechanical analysis (DMA) and four-probe method. The stress–strain curves and electrical conductivity properties were obtained. Scanning electron microscopy (SEM) was used to characterize both agglomeration and porosity formation. By employing micromechanics, through representative volume element (RVE), finite element analysis (FEA) and resistor network model (RNM), the Young’s modulus and electrical conductivity values were calculated. The samples’ elastic moduli showed an increment, reaching the maximum value at a CNTs fraction of 2%, thereafter an adverse effect was caused in the high CNT percentage samples. The final electrical conductivity seemed greatly altered with the addition of CNTs, reaching the percolation threshold at 2%. The unavoidable formation of CNT agglomerates appeared to influence the final physical properties. The CNT agglomerates adversely affect the mechanical performance of high-CNT-percentage samples. Conversely, an exponential increment in the electrical conductivity was presented as the agglomerates formed networks allowing the transport of electrons through the tunnelling effect. These phenomena were experimentally and numerically confirmed, showing a good correlation.

Structure–property relationships and constitutive viscoelastic behaviors of polyether‐block‐amide elastomers in melt and solid states

AbstractIn this study, effects of copolymer composition on the structural, thermal, and viscoelastic properties of segmented multi‐block polyamide elastomers (PEBAX® 3533, 5533, and 6333) and polyamide‐12 (PA12) were quantified by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and dynamic mechanical analysis (DMA) methods and rheological measurements. Soft segment, poly(tetramethylene oxide) (PTMO), contents of copolymers were proved by FTIR analysis. It was found that the increase in PTMO content dramatically reduced the crystallization and melting temperatures and degree of crystallinity values of copolymers. Different rheological test protocols performed in melt state revealed that zero shear rate viscosity values of polyamide elastomers increased with the increasing amount of hard segment. On the other hand, increase in hard segment content yielded lower flow activation energy value. In this study, we mainly focused on understanding quantitative relationships between block copolymer structure and their rheological behaviors and found that the soft segment content of ~40 (mole %) is the critical point for changing the rheological behaviors of block copolymer PAEs, dramatically. DMA measurements implied that the solid‐state viscoelastic behaviors of samples were governed by the hard content of copolymers. Higher hard content decreased long‐term creep strain and creep rate.

The Effect of Starch and Magnetite on the Physicochemical Properties of Polyurethane Composites for Hyperthermia Treatment

In this study, modified polyurethanes (PUs) with starch and magnetite were synthesized in the form of scaffolds for potential applications in orthopedics. Polyurethanes were synthesized using a one-step method. PU synthesis was carried out using poly(ε-caprolactone) 2000 as soft segments and 4,4 ′ -methylenediphenyl diisocyanate (MDI). Various molar ratios of starch and 1,5-pentanediol (PDO) as crosslinker/chain extender were applied, and the effects of incorporating different amounts of magnetite, as well as the role of PDO to starch ratio, were studied. The use of the additive in the form of magnetic particles was to feature the polyurethane materials for use in hyperthermia. The prepared polyurethanes were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA) methods. Scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) analysis and preliminary bioactivity assessment were also performed. The addition of magnetic particles did not cause significant changes in the properties of the obtained materials compared to starch. The tested materials have the potential to be used to fill or replace bone defects in orthopedics, where they can undergo hyperthermia treatment.

Effect of Organic Viscosity-Reducing Warm-Mix Agent on the Performance of Rubber Asphalt

Dynamic mechanical analysis (DMA) and other evaluation methods were used to investigate the effect of WS-1, an organic viscosity-reducing temperature mixing agent, on the rheological and conventional properties of warm-mix rubber asphalt (WMRA). The results demonstrated that the WS-1 warm-mix agent exhibited an excellent viscosity-reducing effect and that, with the increasing of WS-1 content, the high-temperature viscosity of the WMRA decreased significantly. The viscosity and softening point of the WMRA increased at 60 °C simultaneously, with the softening point increasing by about 15 °C. The penetration and ductility decreased by about 1 mm and 6 cm, respectively, and the activation energy (Eη) and temperature sensitivity increased. These results indicated that WS-1 could improve the high-temperature performance of WMRA but had an adverse effect on its low-temperature performance. Upon using temperature scanning for the WMRA, the addition of WS-1 significantly increased the rutting factor (G*/sin δ) of the WMRA and greatly improved its rutting resistance within the temperature range examined. The addition of WS-1 changed the viscosity of WMRA, thus affecting the hot-storage stability of WMRA at high temperatures.

Simultaneous measurement of elastic constants from dynamic mechanical analysis with digital image correlation

Dynamic mechanical analysis (DMA) method is used for measuring viscoelastic properties of materials. The governing equations used for calculating modulus neglect shear deflection component and use an assumption of constant Poisson's ratio in absence of methods that can conduct full field deformation measurement. The present work is focused on using an in-situ imaging method to obtain the full field displacement during the specimen deformation. Digital image correlation is used to calculate the values of Poisson's ratio over temperature and strain to implement a correction factor in the complex moduli calculations. The method developed in this work will provide accurate measurements of viscoelastic properties of polymers, especially for materials whose properties are very sensitive to Poisson's ratio values and temperature variations.

Explanation on the Abnormal Behavior during the Nanoindentation Holding Stages by Amplifying Oscillation

Recently, the holding states of nanoindentation experiments have been widely used to analyze the time-dependent deformations of various rocks, and the dynamic mechanical analysis (DMA) method seems to be more applicable than the quasi-static mechanical analysis (QMA) method when the influence of creep deformation on mechanical properties of rocks was analyzed. However, the former method causes an abnormal behavior during the creep holding stages that was not clearly interpreted.2 Consequently, in this study, by amplifying the oscillation of the DMA method, the mechanical mechanism of this phenomenon was explained. Experimental results confirm that the rheological deformation of rocks consists of the creep deformation (depth increasing) and the elastic aftereffect deformation (depth decreasing) during the creep time with small oscillation; once the elastic aftereffect deformation exceeds the creep deformation, the abnormal behavior can be observed. Besides, some other abnormal behaviors might be found for other rock materials when the DMA method with different oscillations is used, which illustrates the complexity and limitation of applying this method. Thus, the QMA method was recommended to investigate the above questions in future studies.

Investigating the thermo-mechanical and UV-shielding properties of a nano-porous Zr(IV)-type metal-organic framework (MOF) incorporated epoxy composite coating

In the present work, the effects of UIO-66 nanoparticles on the epoxy-polyamide composite coating thermal resistance, mechanical features, and weathering (UV) resistance were explored. The nanoporous UIO-66 particles were developed by the common solvothermal procedure. The final particles were identified by Brunauer–Emmett–Teller (BET), Fourier transform infrared (FT-IR) spectroscopy, and Raman analysis. Also, the thermal properties, as well as the mechanical characteristics of the epoxy nanocomposites loaded with 0.2, 0.4, 0.8, and 1.2 wt% of the UIO-66 particles were studied by thermal gravimetric analysis (TGA), tensile, and dynamic mechanical thermal analysis (DMTA) methods. Besides, the UIO-66 particles containing composite coatings UV resistance at various loadings were studied after 500 h exposure to UV-A irradiation (320–400 nm range) via spectrophotometer analysis, contact angle test, surface roughness analysis, and micro-hardness investigation. BET surface area analysis illustrated a surface area (SA) of 820 m2 g−1 for the constructed metal-organic framework (MOF) particles. TGA outcome exhibited that the temperature related to the weight loss of 80% in the presence of nanoparticles (NPs) increased up to approximately 60 °C. On the other hand, the tensile analysis outcomes indicated that the toughness and strain values related to the breaking of the film increased about 2.1 and 1.5 times (at 1.2 wt% filler loading), in comparison with the pure (un-filled) epoxy matrix, respectively. The DMTA test outcomes demonstrated significant improvements of the UIO-66 particles loaded epoxy coatings storage modulus in the glassy region (especially at 1.2 wt%) and crosslinking density (especially at 0.8 wt%). Results proved that the thermal and mechanical characteristics of the nanocomposite were promisingly improved compared to the pure epoxy. Results proved significant epoxy film UV-shielding properties enhancement in the presence of 1.2 wt% UIO particles.

Dynamic and Wrench-Feasible Workspace Analysis of a Cable-Driven Parallel Robot Considering a Nonlinear Cable Tension Model

Cable-driven parallel robots (CDPRs) have several advantages and have been widely used in many industrial fields, especially industrial applications that require high dynamics, high payload capacity, and a large workspace. In this study, a design model for a CDPR system was proposed, and kinematic and dynamic modeling of the system was performed. Experiments were carried out to identify the dynamic modulus of elastic cables based on the dynamic mechanical analysis (DMA) method. A modified kinematic equation considering cable nonlinear tension was developed to determine the optimal cable tension at each position of the end-effector, and the wrench-feasible workspace was analyzed at various motion accelerations. The simulation results show that the proposed CDPR system obtains a large workspace, and the overall workspace is satisfactory and unrestricted for moving ranges in directions limited by the X-axis and the Y-axis from −0.3 to 0.3 m and by the Z-axis from 0.1 to 0.7 m. The overall workspace was found to depend on the condition of acceleration as well as the moving ranges limited by the end-effector. With an increase in external acceleration, the cable tension distribution increased and reached a maximum in the case of 100 m/s2.

In‐reactor blends based on ultrahigh molecular weight polyethylene: Effect of microstructure of modifying fraction on the morphology and viscoelastic behavior of blends

AbstractA morphology and viscoelastic behavior of a wide range of in‐reactor blends (RBs) on the base of ultrahigh molecular weight polyethylene (UHMWPE) with Mw = 1000 kg mol−1 and polymer fractions of different microstructure were investigated to develop the understanding of relationships between the structure and properties of polyolefin materials. Linear low‐molecular weight polyethylene of high density (LMWPE) with Mw = 160 kg mol−1 as well as ethylene/1‐hexene copolymers (CEH‐n) containing from 3 to 19 mol% of 1‐hexene were used as the components of RBs. In‐reactor blends UHMWPE/CEH‐n and UHMWPE/LMWPE with a varied content of CEH‐n or LMWPE fractions were prepared in the two‐step polymerization processes of ethylene homo‐ and copolymerization over metallocene catalyst. It was found by the methods of differential scanning calorimetry (DSC) and Wide Angle X ray Scattering (WAXS) methods, that the percentages of crystalline and amorphous phases and the lamella sizes in the materials depend on the nature and amount of modifying polymer fractions. Linear dependences of α‐relaxation temperature on the lamella sizes in crystalline phase and β‐relaxation temperature on the density of butyl branches in copolymer fractions of in‐reactor blends UHMWPE/CEH‐n were found by the method of dynamic mechanical analysis (DMA) method. The mechanisms of the processes of α‐ and β‐relaxations in the in‐reactor blends including polymer fractions with different microstructure are discussed.

Сопротивление хрупкому разрушению и демпфирующие свойства слоистых металлополимерных композитов

One of the topical trends in modern materials science is the development and study of new layered metal-polymer composites, which are increasingly used in aerospace engineering, automotive and transport engineering. The metal base of these composites provides a high level of strength properties and impact strength, and the polymer interlayer allows obtaining high damping properties due to its ability to dissipate the energy of elastic vibrations. Of a considerable practical interest is one of the varieties of metal-polymer composite materials based on a sandwich structure — layered steel-rubber composite characterized by pronounced viscoelastic properties, which allows them to be used as vibration damping elements in transport systems. In this work, the possibility of obtaining promising layered metal-rubber composites based on low-carbon steels (Fe-2Mn-1Si steel, IF steel), aluminum alloy Al-Mg3 and heat-and-frost-resistant rubber V-14-1NTA by hot pressing is studied. The influence of the composition and design of composites on the impact strength at temperatures of 20 and −60°C and the damping ability characteristics of materials such as the tangent of the angle of mechanical losses (tg δ), the modulus of elasticity (E') and the modulus of viscosity (E'') are determined by the method of dynamic mechanical analysis. The possibility of using layered metal-rubber composites with increased resistance to brittle fracture in the region of low climatic temperatures, as well as in structural elements of transport systems with high vibration resistance is shown.

Digital differential spectrometry in the assessment of the structural characteristics of wood and wooden composite materials

The results of the application of digital differential spectrometry in the processing of the results of the study of the structure of wood and wood materials by dynamic mechanical analysis (DMA) are shown. The experimental temperature dependences of the dynamic shear modulus G’ are smoothed using cubic splines. Smooth curves G‘(t) are obtained that are suitable for automated processing, including for finding the temperature derivatives of G’. The analysis of the temperature dependences of the first and second derivatives of the dynamic shear modulus allows us to determine the position, range, and intensity of temperature transitions in the components of the material under study. The results of the practical application of the DMA method and digital data processing are presented on the example of studying the dynamic mechanical characteristics of birch wood, apple wood, composite material made of hydrolyzed wood, particle board. It is shown that the use of digital processing of experimental data provides more accurate results, simplifies their interpretation, and expands the understanding of the processes occurring in wood materials at the level of intermolecular interaction.

Curing characterization of tannin-hexamine adhesive by automated bonding evaluation system, dielectric analysis, and dynamic mechanical analysis

The characterization of the curing process allows the determination of the optimal pressing parameters, which is essential for the economical production of wood-based composites. In this study, an automated bonding evaluation system (ABES), dielectric analysis (DEA), and dynamic mechanical analysis (DMA) were used to determine the curing parameters of biobased pine tannin-hexamine adhesive at five temperatures ranging from 75 to 175 °C. This study aimed to compare the three above methods and to find correlations between them. All methods showed the same trend of the curing process, which became faster with increasing temperature. Due to various heating rates among the different methods, the curves representing the degree of cure were shifted to the left for the period in which nearly isothermal conditions were reached. It was determined that these methods could be mutually comparable. The ABES was regarded as the reference method; the DEA was regarded as a method that overestimates the curing process and that describes the beginning of the curing process more precisely; and the DMA method was regarded as a method that underestimates the curing process and that describes the end of the curing process more precisely. Linear trend lines were found between the observed methods.

Effect of Poly(Titanium Oxide) on the Viscoelastic and Thermophysical Properties of Interpenetrating Polymer Networks

The influence of poly(titanium oxide) obtained using the sol-gel method in 2-hydroxyethyl methacrylate medium on the viscoelastic and thermophysical properties of interpenetrating polymer networks (IPNs) based on cross-linked polyurethane (PU) and poly(hydroxyethyl methacrylate) (PHEMA) was studied. It was found that both the initial (IPNs) and organo-inorganic interpenetrating polymer networks (OI IPNs) have a two-phase structure by using methods of dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The differential scanning calorimetry methods and scanning electron microscopy (SEM) showed that the presence of poly(titanium oxide) increases the compatibility of the components of IPNs. It was found that an increase in poly(titanium oxide) content leads to a decrease in the intensity of the relaxation maximum for PHEMA phase and an increase in the effective crosslinking density due to the partial grafting of the inorganic component to acrylate. It was shown that the topology of poly(titanium oxide) structure has a significant effect on the relaxation behavior of OI IPNs samples. According to SEM, a uniform distribution of the inorganic component in the polymer matrix is observed without significant aggregation.

Physics-mechanical and viscoelastic properties of polymer compositions based on synthetic oligomer ED-20 and epoxidized soybean oil

The work was aimed at studying the effects of combining epoxidized soybean oil (ESO) with standard bisphenol type A epoxy resin (ED-20). The ED-20 / ESO ratios were 100/0, 90/10, 95/15 and 80/20 (wt%). The system was cured with amine hardener mono(cyanethyl) diethylenetriamine (MCDT), triethanolamine (TEA) and mixture thereof (TEA + MCDT) at different curing temperatures. The choice was based on the hardener’s ability to open oxirane cycles, form a spatial network and initiate several parallel reactions. The viscoelastic properties, mechanical properties (tensile strength and elongation) were studied the density of obtained ED-20 / ESO samples was determined. The results showed that the introduction of ESO into epoxy resin ED-20 was accompanied by significant changes in the curing and final properties of the samples. It was shown that the physic- mechanical properties of polymer compositions ED-20 / ESO were determined by both the ESO content and the temperature of curing Depending on the selected curing mode, the addition of 5–10 wt.% of ESO increased the tensile strength relative to the σр value of the original epoxy matrix. The values of relative elongation increased significantly at 15-20 wt.% of ESO. By the method of dynamic mechanical analysis it was shown that the increase of ESO content leads to plasticization of epoxy composition and to reduction of crosslinking density. It was determined that 5-10 wt.% was the optimal concentration of ESO, at which the epoxy composition had improved physical and mechanical properties Further increase of ESO content reduced the crosslinking density and increased the defectiveness of the epoxy polymer, which causes premature failure in weak places of the structure under load.

Interlayer bonding between thermoplastic composites and metals by in‐situ polymerization technique

AbstractFiber‐metal laminates (FMLs) offer the superior characteristics of polymer composites (i.e., light weight, high strength and stiffness) with the ductility and fracture strength of metals. The bond strength between the two dissimilar materials, composite and metal, dictates the properties and performance of the FMLs. The bonding becomes more critical when the polymer matrix is thermoplastic and hydrophobic in nature. This work employed a novel bonding technique between thermoplastic composites and a metal layer using six different combinations of organic coatings. The flexural, and interlaminar shear strength of the thermoplastic fiber metal laminates (TP‐FMLs) were examined to investigate the bond strengths in the different cases along with fracture characteristics revealed from the tested samples using scanning electron microscopy. The viscoelastic performance of the fabricated TP‐FMLs were also investigated using the dynamic mechanical thermal analysis method.

СТОЙКОСТЬ УГЛЕПЛАСТИКОВ И СТЕКЛОПЛАСТИКОВ НА ОСНОВЕ РАСПЛАВНЫХ СВЯЗУЮЩИХ К ВОЗДЕЙСТВИЮ УМЕРЕННО ХОЛОДНОГО И УМЕРЕННО ТЕПЛОГО КЛИМАТА

In this work has been investigated the climatic resistance of carbon and fiberglass polymers for aviation purposes based on solvent-free binders VST-1208, VSE-1212, VSR-3M after 3 years of exposure of these materials in the moderate cold climate of Moscow and the moderate warm climate of Gelendzhik. The effect of destruction, post curing, plasticization of binders on the compressive and flexural strengths of carbon plastics VKU-27L, VKU-39, VKU-46 and fiberglass plastics VPS-47/7781, VPS-48/778 was determined using the methods of profilometry, moisture transfer and dynamic mechanical analysis. It is shown that while determining the state of PCM after climatic exposure, it is necessary to take into account the effects of the reversible plasticizing action of moisture. A comparison is made of the climatic resistance of the investigated materials.

Dynamic characteristics of three-layer beams with load-bearing layers made of alumino-glass plastic

Aluminum-fiber-reinforced plastics (GLARE) are promising aviation materials with increased characteristics of specific stiffness and strength, fatigue strength, impact resistance, and residual strength after impact. Nowadays, GLARE are used for making elements of the fuselage of the long-haul passenger aircraft Airbus A380, as well as some other elements of aircraft structures. The results of experimental studies of eigenfrequencies and damping coefficients of three-layer beams made with face sheets of five-layer GLARE and with a core made of polyimide foam are presented. The tests were performed using the method of free bending vibrations of cantilever samples. The dynamic parameters of the three-layer beams were calculated based on the analysis of amplitude-frequency characteristics obtained by the fast Fourier transform method. Mechanical characteristics of GLARE and filler samples are preliminary determined in static and dynamic tests. The damping factor of the core is determined by the dynamic mechanical analysis method. The core shear modulus is determined by measuring the flexural rigidity of manufactured three-layer beams in a quasi-static three-point bending test. Based on a comparison of the design data and the results of the experiments, it is shown that in dynamic tests, the flexural rigidity of three-layer specimens is reduced in comparison with the estimated values, which may be due to the peculiarities of changing the characteristics of the foam core under dynamic loading. The value of the damping factor of GLARE samples was ~0.02, the foamed core was ~0.08 and three-layer beams were ~0.067 in the range of vibration frequency up to 60 Hz.