Dynamic Mechanical Analysis Research Articles

Influence of fish-scale powder addition and stacking order on mechanical and thermal properties of hybrid kenaf/glass polyester composites

The increasing concern for the environment has driven a surge in popularity of utilizing modern technology to develop new products from renewable resources. To address this, polymer composites are incorporating various bio-waste materials as filler components. This study focuses on fabricating four-layered hybrid polyester laminates using kenaf (K), glass (G), and reinforced with fish scale (FS) powder at concentrations ranging from 5 wt.% to 15 wt.%. Mechanical properties are assessed following ASTM standards to evaluate the optimal FS filler percentage. The results reflect that the KGKG laminate with 15 wt. % FS exhibits utmost tensile strength and hardness, while the same laminate with 10 wt. % FS shows optimal flexural and impact properties. Further, numerical analysis is performed using ANSYS 19.0 software to validate the experimental findings. It is marked that, the results of numerical analysis are align intimately with the experimental data, with a deviation of 5 to 10%. Additionally, the moisture absorption behavior is investigated, and the results revealing that FS filler reduced moisture uptake and enhanced dimensional stability. Further, the study is extended to investigate the thermal attributes of laminates through Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA). The fractured surface morphology are studied through Scanning Electron Microscopic (SEM) and the findings reveal significant occurrences of matrix cracking, fiber withdrawal, and the separation of fibers from the matrix. Overall, this study suggests the incorporation of FS bio-fillers into hybridized kenaf/glass laminates in order to improve performance and create environmentally friendly options that suitable for automotive applications.

Development of Flexible and Partly Water-Soluble Binder Systems for Metal Fused Filament Fabrication (MF3) of Ti-6Al-4V Parts.

Metal Fused Filament Fabrication provides a simple and cost-efficient way to produce dense metal parts with a homogenous microstructure. However, current limitations include the use of hazardous and expensive organic solvents during debinding for flexible filaments the stiffness of filaments made from partly water-soluble binder systems. In this study, the influence of various additives on different partly water-soluble binder systems, with regard to the flexibility and properties of the final parts, was investigated. Furthermore, a method using dynamic mechanical analysis to quantify the flexibility of filaments was introduced and successfully applied. For the first time, it was possible to produce flexible, partly water-soluble filaments with 60 vol.% solid content, which allowed the 3D printing of complex small and large parts with a high level of detail. After sintering, density values of up to 98.9% of theoretical density were achieved, which is significantly higher than those obtained with existing binder systems.

Fabrication and thermomechanical property investigations of polypropylene/silica and polypropylene/modified silica composite films

In this study, we fabricated polypropylene/silica (PP/S) and polypropylene/modified silica (PP/MS) composite films using the extrusion technique, and characterized, and investigated their thermomechanical behaviors. The characterization of the neat materials and prepared composites was successfully conducted using some advanced spectroscopic techniques. The thermal stability and thermomechanical behaviors of the composites were investigated through thermogravimetry analysis (TGA) and dynamic mechanical analysis (DMA). The tensile tests revealed that the PP/MS composites exhibited the highest strength values, reaching 22.23 MPa with 1.0 % MS. Higher tensile strength was obtained with PP/MS composites compared to PP/S composites, proving the clear effect of the hexadecyltrimethylammonium bromide (HTAB) binder in the composition of the composites. The highest strength values obtained with the PP/S composites were 20.10 MPa at a ratio of 2.5 %.

A Dynamic Mechanical Analysis on the Compatibilization Effect of Two Different Polymer Waste-Based Compatibilizers in the Fifty/Fifty Polypropylene/Polyamide 6 Blend.

This study aims to examine the 50/50 polypropylene/polyamide 6 (iPP/PA6) system molded under confined flow conditions, both in its original state and after being modified by two different interfacial agents. This study provides two main insights. Firstly, it focuses on a polymer blend close to phase inversion. Secondly, it investigates the impact of using two different types of interfacial agents (derived from polymer waste) to enhance the compatibility between iPP and PA6. Dynamic Mechanical Analysis (DMA) has been employed to achieve these objectives. It is important to note that the investigation of the 50/50 iPP/PA6 system is a crucial focus predicted in previous studies, where a series of mechanical properties were evaluated using Box-Wilson design of experiments (DOEs) over the whole compositional range on the iPP/PA6 binary system. Thus, two interfacial modifiers, namely succinic anhydride (SA)-grafted atactic polypropylene with terminal, side, and bridge SA grafts (aPP-SASA) and succinyl-fluoresceine (SF) with bridge succinic anhydride grafting atactic polypropylene (aPP-SFSA), were employed. The authors obtained and characterized these agents. The quantity of these agents used in the blend was identified as a critical coordinate in prior studies conducted by the authors. The processing method used, compression molding under confined conditions, was chosen to minimize any orientation effect on the emerging morphology. All characterization procedures were performed on samples processed by contour machining to retain the blend morphologies as they emerged from the processing stage. Results from WAXS and SAXS synchrotron tests concluded there were no changes in the crystal morphology of the iPP or the PA6 in the blends nor any co-crystallization process throughout the compositional range. These findings, and the long period fits on the PP crystalline phase for the fifty/fifty blends we are discussing, will support the present DMA study. Finally, the efficiency of these interfacial modifiers has been concluded, even in this unfavorable scenario.

Preparation and Characterization of Biocomposites Based on Fibrous Brucite and Poly (Butylene Succinate)

In our research described in this manuscript, fibrous brucite (FB) was modified with common silane coupling agent (KH-570) and the facile melt blending method was used to fabricate fibrous brucite/poly(butylene succinate) (FB/PBS) composites. To evaluate the influence of surface modification of the FB, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that the KH-570 reacted with brucite and the treated FB (OFB) could be well dispersed in the polymer matrix. The mechanical properties and dynamic mechanical analysis (DMA) results showed the effect of the surface modification on the tensile strength, impact strength, storage modulus and glass transition temperature (Tg), which were enhanced with the incorporation of the treated FB in the composites. The flame retardancy of the FB/PBS composites was improved significantly, indicating that the FB could be used as an efficient flame retardant. The addition of FB deteriorated the thermal stability of the PBS. However, the loss in thermal stability was exchanged for a considerable increase in the mechanical and flame retardancy properties. The prepared composites demonstrated better mechanical and flame retardancy properties, compared to PP or PP composites, presenting the potential to be widely used in various industrial fields.

Improving the Sustainability of Enzymatic Synthesis of Poly(butylene adipate)-Based Copolyesters: Polycondensation Reaction in Bulk vs Diphenyl Ether.

In response to mounting global concerns such as CO2 emissions, environmental pollution, and the depletion of fossil resources, the field of polymer science is shifting its focus toward sustainability. This research investigates the synthesis of poly(butylene adipate)-co-(dilinoleic adipate) (PBA-DLA) copolymers using two distinct methods: bulk polycondensation and polycondensation in diphenyl ether. The objective is to assess the environmental impact, chemical structure, composition, and key properties of the resulting copolymers, with a particular emphasis on determining the viability of bulk synthesis as a more sustainable approach. Various analytical methods, including nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and size exclusion chromatography, were employed to confirm successful copolymerization and highlight differences in molecular weight and microstructure. Additionally, thermal and dynamic mechanical analyses were conducted to thoroughly characterize the copolymers' properties. This research provides significant findings into the sustainable production of PBA-DLA copolymers, offering a more environmentally friendly approach without compromising product quality or performance.

Investigating the role of solvents in modulating glass transition and dynamic mechanical characteristics of polystyrene film

This study investigates how different solvents impact the glass transition and dynamic mechanical properties of polystyrene (PS) films. Using FTIR spectroscopy, it analyzes solvent-induced variations in molecular vibrations, particularly in the phenyl ring region. Results show solvent-specific effects on the 750 cm-1 peak, associated with the "meta-substituted aromatic ring," influencing phenyl ring vibrations. DSC analysis highlights solvent effects on the glass transition temperature (Tg), revealing complexities in PS films prepared with chloroform, tetrahydrofuran (THF), and toluene. Varied Tg behavior suggests solvent-driven structural modifications and gradual solvent removal. Dynamic Mechanical Analysis (DMA) demonstrates solvent-dependent changes in storage modulus, loss modulus, and tan δ, indicating solvent polarity role in polymer chain dynamics. Toluene-induced plasticization reduces Tg and increases creep compliance, revealing PS film sensitivity to solvents. These findings stress solvent selection importance in tailoring thermal and mechanical properties of polymer films for specific applications.

A novel rigidizable inflatable lunar habitation system: design concept and material characterization

Constructing lunar bases is crucial as lunar missions progress towards utilization and exploitation. The challenging lunar environment, with its unique characteristics and limited resources, requires special materials, structures, and construction methods. Inflatable structures offer great potential for lunar construction due to their advantages in transportation, stowage, construction, and reliability. This paper proposes a rigidizable inflatable lunar habitat that maintains its shape even after air leakage, enhancing safety, durability, and fixability. The membrane material adapts to different requirements during transportation, construction, and service, achieved through solid-state actuation of shape memory polymer (SMP) for stiffness variation, allowing multiple moves and ground tests. This work comprises three parts: 1) system: design concept and construction processes, 2) material: design and characterization of restraint and rigidization materials, and 3) structure: numerical validation of structure properties. Finite element analysis, based on material models obtained through dynamic mechanical analysis (DMA) and tensile tests, demonstrates the effectiveness of including an SMP rigidization layer in preventing collapse and enhancing dynamic properties. This paper not only proposes a new system, but also provides material design methods and requirements, along with structural validation techniques. Findings validate the feasibility of rigidizable inflatable lunar habitats, applicable in extreme environments, also in temporary buildings, space structures, and soft robotics.

Numerical study on the forward and inverse problems of the mobile pump truck frame

Aiming at the requirements of strong mobility and high flexibility of rescue and relief mobile pump trucks, this paper designs a new type of mobile pump truck frame based on existing mobile vehicle frame models. The materials used for the frame are 40Cr and Q235, and the finite element method is utilized to carry out static mechanical analysis and dynamic characteristic analysis. Simultaneously utilizing topology optimization and multi-objective genetic algorithm to optimize the design of the frame structure. The results show that the optimized pump truck frame can meet the strength design requirements of four typical working conditions: full load bending, full load torsion, emergency turning and emergency braking, while avoiding resonance phenomena caused by road surface and diesel engine vibration. Compared with the original frame model, the weight of the optimized frame is reduced by 87.88 kg, with a weight reduction rate of 10.89%, realizing the lightweight design requirements.

Mechanical and optical properties assessment of an innovative PDMS/beeswax composite for a wide range of applications

Polydimethylsiloxane (PDMS) is an elastomer that has received primary attention from researchers due to its excellent physical, chemical, and thermal properties, together with biocompatibility and high flexibility properties. Another material that has been receiving attention is beeswax because it is a natural raw material, extremely ductile, and biodegradable, with peculiar hydrophobic properties. These materials are applied in hydrophobic coatings, clear films for foods, and films with controllable transparency. However, there is no study with a wide range of mechanical, optical, and wettability tests, and with various proportions of beeswax reported to date. Thus, we report an experimental study of these properties of pure PDMS with the addition of beeswax and manufactured in a multifunctional vacuum chamber. In this study, we report in a tensile test a 37% increase in deformation of a sample containing 1% beeswax (BW1%) when compared to pure PDMS (BW0%). The Shore A hardness test revealed a 27% increase in the BW8% sample compared to BW0%. In the optical test, the samples were subjected to a temperature of 80 °C and the BW1% sample increased 30% in transmittance when compared to room temperature making it as transparent as BW0% in the visible region. The thermogravimetric analysis showed thermal stability of the BW8% composite up to a temperature of 200 °C. The dynamic mechanical analysis test revealed a 100% increase in the storage modulus of the BW8% composite. Finally, in the wettability test, the composite BW8% presented a contact angle with water of 145°. As a result of this wide range of tests, it is possible to increase the hydrophobic properties of PDMS with beeswax and the composite has great potential for application in smart devices, food and medicines packaging films, and films with controllable transparency, water-repellent surfaces, and anti-corrosive coatings.

Experimental and theoretical analysis on the thermomechanical properties of functionally graded graphene nanoplatelet reinforced cement composites

Graphene reinforced cement composites (GRCCs) have attracted great attention due to their excellent mechanical and physical properties. Instead of uniform distribution, the functionally graded distribution of graphene fillers can effectively utilize the mechanical and physical properties of the reinforcements while reducing cost. This paper is the first attempt to combine experimental analysis and theoretical modelling to investigate the thermomechanical properties of functionally graded graphene nanoplatelet (GNP) reinforced cement composites (FG-GNPRCCs). Samples with uniform (profile H) and functionally graded (profiles X, O and A) distribution of GNPs were prepared and tested. Among all the FG distribution patterns as involved, profile X exhibited the most pronounced enhancement. Compared to the uniform distribution at room temperature, the loss factor and storage modulus of profile X increased by 19.3 % and 19.5 %, respectively. Based on the effective medium theory (EMT) and Mori-Tanaka (MT) model, a parallel triple-inclusion model was developed to predict the thermal conductivity of GNPRCCs. The effects of coated GNP, agglomeration and the attributes of pores (i.e., size, shape and porosity) on the thermomechanical properties of the composites were considered. Dynamic mechanical analysis revealed that profile X had the best energy dissipation and the extent of inelastic deformation within the temperature range from −50 °C to 70 °C. In contrast, profile A is beneficial for scenarios that desire a gradual transition and controlled stress along a certain direction.

Integrating dynamic relaxation with inelastic deformation in metallic glasses: Theoretical insights and experimental validation

Metallic glasses (MGs), a metastable material far from equilibrium, exhibit intricate dynamic relaxation behaviors. The challenge lies in developing a model that accurately describes the dynamics and deformation mechanisms of MG. This paper introduces a model integrating dynamic relaxation with deformation behavior. Validation through dynamic mechanical analysis, stress relaxation, creep, and strain recovery tests confirm the existence of four deformation modes: elasticity, anelasticity from β relaxation, anelasticity from α relaxation at low temperatures, and viscoplasticity from α relaxation at high temperatures. The model captures all of these deformation modes. The dynamical mechanical spectrum and stress relaxation spectrum unveil dynamic features during glass to liquid transition, and a simple and effective experimental method was developed for identifying ultra-low-frequency dynamic relaxation. This work provides new perspectives on the study of relaxation dynamics in glassy states and establishes important connections between dynamic relaxation behavior and deformation mechanisms. These findings lay a theoretical and experimental foundation for the broad application of MGs.

EFFECT OF CHEMICAL MODIFICATION OF MULTIWALL CARBON NANOTUBES ON THE PROPERTIES OF POLY(LACTIC ACID) COMPOSITE FILMS: SYNTHESIS AND CHARACTERIZATION

To enhance the properties of poly(lactic acid) (PLA) composite films, unmodified (MWCNT) and modified multiwall carbon nanotubes (MWCNT-COOH, MWCNT-OH, and MA-g-MWCNT) were incorporated into the polymer matrix followed by the solvent casting method. The success of the modification of MWCNT with maleic anhydride (MA) was verified by absorption transmission reflectance spectroscopy (ATR). The fabricated nanocomposite films were analyzed by Fourier transform infrared (FT-IR) spectroscopy, thermal analyses, atomic force microscopy (AFM), contact angle measurements, dynamic mechanical analysis (DMA), and electrical conductivity tests. ATR spectra showed that MA was covalently grafted to the surface of the MWCNT, which was well dispersed and homogenously incorporated in the PLA matrix. The results of the thermal degradation demonstrated that the degradation value of the film increased from 328.91oC to 347oC with the addition of 0.5 wt% MA-g-MWCNT. Additionally, the MWCNT-OH/PLA films illustrated strongly hydrophilic nature due to the –OH groups. The surface resistance of 3 wt% of the MWCNT-COOH/PLA nanocomposite film decreased from 2.56x109 to 2.42x103 Ω (by 106 order). Therefore, the properties of PLA were increased with the addition of functionalized MWCNTs, which can be used for different applications such as biomedical, food packaging, and electronics.

Mechanical properties assessment of composite solid propellant based on different aziridine bonding agents

Abstract The employment of the dynamic mechanical analyzer (DMA) represents a modern methodology for the monitoring of the thermo-mechanical characteristics and also the thermomechanical loads of polyurethane-based composite solid rocket propellants during combustion. A meticulous preparation of composite propellant samples based on different bonding agents was carried out to examine the influence of various bonding agents on mechanical properties. To simulate the effects of natural aging, an accelerated aging program was implemented and subjected to the propellant samples for 5-day exposure at 90°C, equivalent to 5 years of natural aging. The dynamic mechanical modern analysis technique was used to assess the viscoelastic behavior and degree of viscoelasticity of both fresh and aged propellant samples. It is concluded that M4 based on MT-X bonding agent is the most valuable formulation of CSRP with tan δ of 0.183591, also with mechanical results; implying that M4 formulation based on MT-X bonding agent has the highest degree of viscoelasticity.

Dynamics and viscoelasticity of potato and corn starch bio-polymers reinforced with bentonite nanoclay

The influence of bentonite nanoclay on the viscoelasticity and dynamics of potato starch (PS) and corn starch (CS) films was investigated. Free standing films were plasticized with glycerol and displayed elastomeric behavior. The addition of bentonite (up to 4 wt%) increased the glass transition temperature Tg of PS/bentonite nanocomposites, however the Tg of CS/bentonite nanocomposites was reduced. On the other hand, bentonite increased the tensile modulus E’ of both type of nanocomposites. Dynamic mechanical analysis (DMA) showed that CS film displayed two mechanical relaxations, named α and α’, whereas PS film displayed only the α relaxation. The α relaxation was associated with the glass transition whereas the α’ relaxation appears to be associated to starch-rich domains due to lower miscibility of CS with glycerol. Rheology showed that bentonite increased the rubbery modulus Ec of the nanocomposites thus explaining the mechanical reinforcement. The starch nanocomposites exhibited exfoliated and intercalated morphologies (at low and higher bentonite content, respectively). Hence, nanoconfinement and domain separation appear to drive the thermo-mechanical properties and dynamics of the starch-based nanocomposites.

Using natural antioxidant Rhubarb extracts in PVA/chitosan bio-adsorbent films for efficient removal of cationic and anionic dyes from polluted water

In this research, sustainable membrane films were developed for removal of cationic and anionic dyes from wastewater based on polyvinyl alcohol/chitosan (PVA/CS) incorporated with natural antioxidant Rhubarb dye (Rh) extracts. Rh dye was extracted from Rhubarb roots by a green method. Three different quantities of Rh dye extracts (i.e., 2.5, 5, and 10 %) were used to fabricate crosslinked PVA/CS films by solvent-casting approach. The fabricated films subjected to different techniques such as X-ray diffraction (XRD), scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX), dynamic mechanical analysis (DMA), as well as antioxidant activity. In all cases, the incorporation of Rh dye extracts inside the composite improved the crystallinity, biocompatibility, stress–strain properties, besides the DPPH scavenging activity reached 42.50 % for PVA/CS-10 % Rh membrane compared to PVA/CS blank (i.e., ∼ 2.10 %). Dyes adsorption including different cationic and anionic dyes implemented for all selected membranes. The data revealed that the membrane containing 10 % Rh dye was the optimum for removal of malachite green oxide (MG, 93 %) as cationic dye and methyl orange (MO, 95.70 %) as anionic dye. Moreover, the kinetics of the removal process exhibited that this process followed the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich models, and the pseudo-1st order kinetic model, with an R2 of 0.998 and 0.943 for MG and MG, respectively. Whereas, the adsorption process corresponded to the Freundlich isotherm model, with coefficients R2 was of 0.989 and 0.988 for MO and MG, respectively. Other parameters including dye concentration, contacting time, pH media, and kinetic studies were also applied on PVA/CS-10 % Rh membrane.

Design and validation of a DMA-inspired device for in-vivo measurement of human skin mechanics: a finite element analysis approach

Abstract This study introduces a novel method for measuring the mechanical properties of human skin in-vivo, inspired by dynamic mechanical analysis (DMA). We designed and applied a DMA-like device to living human skin and validated its functionality through finite element analysis (FEA) on an ideally elastic skin model. The device features multiple testing modes, including horizontal movement in both same and opposite directions with optional pre-stretching. Stress-strain behaviours obtained from FEA align with initial setup parameters, serving as powerful tools for further research into the mechanical properties of skin. This method is expected to have potential significance in biomechanical theory, clinical, and healthcare applications.

Damping properties and mechanism of aluminum matrix composites reinforced with glass cenospheres

The damping properties were improved by preparing Al matrix composites reinforced with glass cenospheres through the pressure infiltration method. Transmission electron microscopy and scanning electron microscopy were employed to characterize the microstructure of the composites. The low-frequency damping properties were examined by using a dynamic mechanical thermal analyzer, aiming at exploring the changing trend of damping capacity with strain, temperature, and frequency. The findings demonstrated that the damping value rose as temperature and strain increased, with a maximum value of 0.15. Additionally, the damping value decreased when the frequency increased. Dislocation damping under strain and interfacial damping under temperature served as the two primary damping mechanisms. The increase in the density of dislocation strong pinning points following heat treatment reduced the damping value, which was attributed to the heat treatment enhancement of the interfacial bonding force of the composites.

Preparation, mechanical analysis and investigation of swelling behavior of boron nitride reinforced hydrogel polymer composite films

AbstractThis study presents the preparation, hydrogel kinetics, and mechanical analysis of Boron Nitride (BN) reinforced PVA/PVP/PEO‐BN hydrogel composite films using Polyvinyl alcohol (PVA), Polyvinyl pyrrolidone (PVP), and Polyethylene oxide (PEO) commercial polymers. Dynamic mechanical analysis tests reveal that PVA90PEO5PVP5‐BN composite films exhibit plastic‐viscoelastic behavior under a maximum force of 18 N. The Young's Modulus values for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20 are 0.22, 0.32, and 0.44 MPa, respectively. The highest % Strain value is observed in PVA90PEO5PVP5‐BN%20, reaching 279.80%. In the hydrogel kinetics study, Schott's and Fickian models are utilized. The regression from the Fickian model is quite low, with exponential diffusion index, n, values lower than 0.5, indicating a classical Fickian water diffusion mechanism. Schott's model provides graphs with significantly higher regression compared to the Fickian model. The results indicate compatibility with the other model and confirm the presence of water‐based diffusion. Equilibrium swelling values (Se, g H2O/g gel) are 6.71, 7.03, and 7.91 for PVA90PEO5PVP5, PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively. Differential Scanning Calorimetry (DSC) analysis results show that the glass transition temperatures, Tg, are 52.37, 60.20, and 63.05°C for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively.

The polytannic acid‐Fe(III) functionalized graphene oxide in poly (propylene carbonate) nanocomposite enabling enhanced shape memory, UV‐resistance, and self‐healing performance

AbstractPolypropylene carbonate (PPC) is a promising candidate of substrate materials used for human wearable devices due to its excellent ductility and biocompatibility. However, PPC is prone to be deformed, thus resulting in poor shape recovery property. One effective solution is to construct composites. In this work, poly (tannic acid) with Fe3+ (FPTA) @ graphene oxide (GO) was added to fabricate FPTA@GO/PPC composites. The results show that FPTA@GO can construct a tight network of hydrogen bonds into PPC to improve shape memory and self‐healing properties. By varying the FPTA@GO content, the composites exhibit tunable shape memory property. Dynamic mechanical analysis confirms that FPTA@GO/PPC composites show better shape memory properties compared with pure PPC. 5 wt% FPTA@GO/PPC composite demonstrates superior shape fixation ratio (Rf = 99%) as well as superior shape recovery ratio (Rr = 94%) in 37°C. Moreover, 5 wt% FPTA@GO/PPC composite possesses great self‐healing efficiency of 81% and tensile strength (17.2 MPa). The UV absorption capacity of 5 wt% FPTA@GO/PPC is increased by 150% (far and mid‐UV regions) and 400% (near‐UV region) compared with pure PPC. Thus, FPTA@GO/PPC composites have potential applications in developing shape memory, self‐healing, and UV‐resistant materials for human wearable devices.