Dynamic-Mechanical Analysis of Selected Composite Materials

Textan Chemicals launches new enzyme for papermaking

Nano-Fe particles were selected as microwave-absorber, and added in the epoxy resin. Epoxy resin/nano-Fe composite materials were cured by microwave irradiation and heating. Vector network analysis, dynamic mechanical analysis(DMA) and scanning electron microscope(SEM) were used to study the curing behaviors of composite materials under the different curing ways. Results show that the dielectric constant(εr) and the dielectric loss factor(tanδ) of the epoxy resin increased obviously when nano-Fe particles were added, and microwave absorption properties of epoxy resin/nano-Fe composite materials improved greatly with increasing contents of nano-Fe particles. DMA results indicate that the storage modulus (E’) and glass transition temperature(Tg) of epoxy resin samples with nano-Fe particles were higher than those without nano-Fe particles. The microstructure and phase composition of the samples were studied by SEM and EDX. Results show that nano-Fe particles were homogeneously dispersed in the epoxy resin matrix under microwave irradiation, which implies improved strength and toughness of epoxy resin/nano-Fe composite materials.

Direct digital manufacturing of continuous fiber-reinforced thermoplastics exhibits the potential to relieve many of the constraints placed on the current design and manufacture of composite structures. At present, the additive manufacturing of continuous fiber-reinforced thermoplastics is demonstrated to varying extents; however, a comprehensive investigation of manufacturing defects and the quality of additively manufactured high fiber volume fraction continuous fiber-reinforced thermoplastic composites is limited. Considering the preliminary nature of the additive manufacturing of continuous fiber-reinforced thermoplastics, composites processed in this manner are typically subject to various manufacturing defects, including excessive void content in the thermoplastic matrix. Generally, quality evaluation of processed composites in the literature is limited to test methods that are largely influenced by the properties of the continuous fiber reinforcement, and as such, defects in the thermoplastic matrix are usually less impactful on the results and are often overlooked. Hardware to facilitate the direct digital manufacturing of continuous fiber-reinforced thermoplastic matrix composites was developed, and specimens were successfully processed with intentionally varied void content. The quality of the additively manufactured specimens was then evaluated in terms of the measured maximum storage modulus, maximum loss modulus, damping factor and the glass transition temperature by means of dynamic mechanical analysis (DMA). DMA allows for thermomechanical (i.e., highly matrix sensitive) evaluation of the composite specimens, specifically in terms of the measured elastic storage modulus, viscous loss modulus, damping factor and the glass transition temperature. Within the tested range of void contents from roughly 4–10%, evaluation by DMA resulted in a distinct reduction in the maximum measured storage modulus, maximum loss modulus and glass transition temperature with increasing void content, while the damping factor increased. Thus, the results of this work, which focused on the effect of void content on DMA measured properties, have demonstrated that DMA exhibits multi-faceted sensitivity to the presence of voids in the additively manufactured continuous fiber-reinforced thermoplastic specimens.

acrylic polyol로 개질한 polyester형 polyurethane foam을 quasi prepolymer법으로 제조하였다. 열적 및 동적 기계적 성질은 thermal gravimetric analysis 및 dynamic mechanical analysis에 의하여 분석하였다. 또한 유리전이온도는 differential scanning calorimeter로 측정하였다. Acrylic polyol 함량이 증가함에 따라 TGA에 의해 측정한 열적 안정성은 약간 감소하였다. 그리고 acrylic polyol 함량이 증가함에 따라 저장 탄성률은 증가한 반면에 tan delta 값은 감소하였다. Polyester type polyurethane foam modified with acrylic polyol was prepared by quasi prepolymer method. Thermal and dynamic mechanical properties of polyurethane foam were analysed by thermal gravimetric analysis(TGA) and dynamic mechanical analysis(DMA). Also, glass transition temperature was measured by differential scanning calorimeter(DSC). As acrylic polyol contents were increased, thermal stability measured by TGA was slightly decreased. Storage modulus was increased and tan delta was decreased with increasing of acrylic polyol contents.

Lightweight and high strength composite materials are vital for unmanned aerial vehicles (UAVs) and aerospace technologies with desired characteristics. Carbon composite materials exhibit extraordinary properties for UAVs and aerospace applications. This study aimed to discover the best-prepared composition of composites material having epoxy LY-5052 and carbon fibres laminate for UAVs. Besides, to develop a low cost with high specific strength composite material for aerospace application to replace metallic alloys. In this work, the vacuum bag technique is used to prepare rectangular strips of three different ratios of carbon fibre/epoxy laminates [(40:60), (50:50) and (60:40)] to obtain the best composite in terms of properties. The thermo-mechanical and viscoelastic behaviour of composite materials were evaluated using differential scanning calorimetry (DSC), universal testing machine (UTM) and dynamic mechanical analysis (DMA). The tensile strength of epoxy LY5052 composites with 60 wt% has enhanced to 986%, and glass transition temperature (Tg) was improved from 71oC to 110oC. Overall, 60 wt% carbon fibre exhibits better thermo-mechanical properties with lightweight, which may be a future composite material for aerospace, especially UAVs technologies.

Automotive underhood electronics are subjected to high operating temperatures in the neighborhood of 150 to 200°C for prolonged periods in the neighborhood of 10-years. Consumer grade off-the shelf electronics are designed to operate at 55 to 85 °C with a lower use-life of 3 to 5 years. Underfill materials are used to provide supplemental restraint to fine-pitch area array electronics and meet the reliability requirements. In this paper, a number of different underfill materials are subjected to automotive underhood temperatures to study the effect of long time isothermal exposure on microstructure and dynamic-mechanical properties. It has been shown that isothermal aging oxidizes the underfill, which can change the mechanical properties of the material significantly. The oxidation of underfill was studied experimentally by measuring oxidation layer thickness using polarized optical microscope. The effect on the mechanical properties was studied using the dynamic mechanical properties of underfill with DMA (Dynamic Mechanical Analyzer). Two different underfill materials were subjected to three different isothermal exposure, which are below, near and above the glass transition temperature of the underfills. The dynamic mechanical viscoelastic properties like storage modulus, loss modulus, tan delta and their respective glass transition temperatures were investigated. Three point bending mode was used in the DMA with a frequency of 1 Hz operating at 3 °C/min.

The elastic properties of Polyester Resin (PR)/Ignimbrite Stone Powder (ISP) composite mortars were determined by measuring ultrasonic wave velocities in the mortars. In the production of composite mortars, ISP with various particle sizes and polyester resin as a matrix were used. The viscoelastic properties of pure PR and PR/ISP composites, such as storage (E′) and loss modulus (E″), damping factor (tanδ) and glass transition temperature (Tg) were determined using Dynamic Mechanical Analysis (DMA). Within the scope of the research, structural characterizations and microscopic surface structures of pure PR and PR/ISP composite mortars were analyzed using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), respectively. The energy transmission coefficients of 5 MHz ultrasonic waves in air at 25°C were found to be 4.9834 × 10−4 for pure PR and 2.6482 × 10−4 for composite mortars with a particle size of 250 μm (CM250), respectively. Based on the analysis of SEM images of materials, including density, ultrasonic velocities, mechanical properties, reflection (R) and transmission (T) coefficients, research findings established CM250 mortar as the optimal choice for restoring heritage structures.Highlights Polyester Resin/Ignimbrite Stone Powder composite mortars were produced. Dynamic mechanical analysis and ultrasonic methods were performed. Storage modulus, loss modulus, and loss tangent values were determined. Composite mortars showed higher elastic and acoustic properties than pure resin.

A new strategy to foaming of Poly(methyl acrylate ‐co‐2‐hydroxyethyl methacrylate) as a polymer with low glass transition temperature (Tg) and strength is proposed by introducing supramolecular interactions via quadruple hydrogen bonding ureido‐pyrimidinone (UPy) units. The supramolecular polymers formed a reversible amorphous network and are foamed in a batch process inside an autoclave using supercritical N2. The thermal and dynamical behaviors of unfoamed and foamed supramolecular polymers are studied by differential scanning calorimeter and dynamic mechanical thermal analysis. The presence of UPy units in poly(methacrylic acid‐co‐2‐hydroxyethyl methacrylate) forms a reversible amorphous network and slows down the chains dynamics and leads to increase in the glass transition temperature as well as elastic modulus before and after foaming. The cellular structures, obtained in different foaming temperature, saturation pressure, and UPy content, were investigated using scanning electron microscopy. The higher density of UPy units induced more stability and higher elastic modulus and developed the more stable, closed, and homogenous cell structure with higher expansion ratio and cell. The obtained results show that the supramolecular polymer can be foamed with appropriate cellular structure integrity and uniform cell size distribution at 90°C, 9 MPa, and 4.5 mol% UPy content.

The stress relaxation, creep-recovery, temperature, and frequency sweep tests were performed within the linear viscoelastic region by using a dynamic mechanical analyzer to investigate the viscoelastic characteristic of oat grain. The result showed that 5-element Maxwell and Burgers model were able to describe viscoelastic behaviors better. The relaxation stress decreased with the increasing moisture content from 6.79 to 23.35%, while the creep strain increased as well as the final percentage recovery decreased from 58.61 to 32.50%. In frequency sweep, storage modulus increased with the increasing frequency. In temperature sweep, there was a clear turning point in storage modulus, loss modulus, and tan delta curves with increasing temperature. The turning value of 167.47, 147.44, 134.27, 132.41, 110.28, and 92.62 °C detected in the tan delta were regarded as the best glass transition temperatures. This temperature was found to be lower than gelatinization heating temperature and decrease with the increase of moisture content. The crystalline structure of oat exhibited a typical A-type pattern and corresponding crystallinity increased from 22.03 to 31.86% with increasing moisture content. The scanning electron microscopy (SEM) micrograph of oat section was found that the size and adhesive effect of starch granules increased due to hydration.

Modified epoxy composites have become attractive materials for various applications including coatings, polymer concrete, and with asphalt as steel bridge pavement material. In such applications, it is important to maintain high chemical and mechanical resistance to avoid load cracking and corrosion resulted from chemicals exposures. The purpose of this study is to produce sulfur/epoxy composites with excellent mechanical and chemical properties and able to be applied easily in a wide range of applications. the epoxy resin was mechanically mixed with different percentages of sulfur and linseed oil to form sulfur/epoxy composites. Where sulfur is well incorporated into the epoxy matrix. The prepared composites were characterized by dynamic mechanical analysis including storage modulus, loss modulus, and tan delta. In addition, the chemical and water absorption resistance was tested including two hours boiling water absorptance resistance and long-term water absorptance resistance. the results showed enhanced storage modulus, glass transition temperature, chemicals, and water absorption resistance. Also, it is observed that as the concentration of sulfur increases, the mechanical and chemical resistance properties increase.

In this research, a novel eco-friendly green composite is fabricated by combining a biomatrix composed of a biopolymer, date palm fiber, and a filler obtained from discarded eggshell (ES) waste material. This research aims to check the influent of ES filler on thermal and viscoelasticity properties of bio-epoxy composite with incorporation of 40 wt.% date palm (DP) fiber. Various ES filler ratios, specifically 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%, are dispersed into the composite. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) approach were employed to investigate the properties of fabricated composites as a function of temperature in terms of storage modulus (E′), loss modulus (E′′), Tan delta (Tan δ), glass transition temperature (Tg), and Cole-Cole plot. Overall, incorporating ES filler into the bio-epoxy/DP fiber composites increased E′, E′′, and Tg significantly. ES-filled composites containing 5 and 10 wt.% exhibited properties comparable to 15 wt.% but less than 20 wt.% ES filler. Thermal tests result show that 20 wt.% ES-filled materials outperform their counterparts in terms of heat resistance or thermal stability. The evidence suggests that the embodiment of ES filler in bio-epoxy/DP fiber composites yields enhancements in both thermal and dynamic mechanical properties. This indicates the potential for utilizing ES filler loading in advanced composite applications that prioritize thermal stability and sustainability.

Analysis of dynamic mechanical properties of photochemically crosslinked poly(isobornylacrylate-co-isobutylacrylate) applying WLF and Havriliak-Negami models

Cross-linking kinetics study and high temperature mechanical properties of ethylene–octene copolymer (EOC)/dicumylperoxide(DCP) system

The aim of the study is to do an experimental analysis and investigation of visco-elastic behaviour of CFRP hybrid nanocomposites, which contains the small percentage of nanoclay and nanoZnO particles mixed for the improvement in the various properties of the CFRP composites. Also there is try to focus on the combined effect of another variable, i.e., fiber angle of orientation along with changing the percentage of nano particles.A hand layup method followed by process of vacuum bagging was used to make the samples of composite. Dynamic mechanical analyzer (DMA) was used to inspect the dynamic mechanical properties of CFRP hybrid nanocomposite specimens with changing temperature. The OVAT analysis is carried out for three mentioned variables and studied effect of variables on the various visco elastic properties like flexural storage modulus, loss modulus, Glass transition temperature and tan etc. It is found that due to the presence of nano particles there is tremendous change in the value of storage modulus ,it gets almost doubled, i.e., 200%because of the presence of nano particles. The experimental result also shows the positive effect on the loss modulus because of the nano particle contribution .Similarly there is considerable change in GTT(Glass transmission temperature) and change in length in DMA (Dynamic mechanical analysis ).

In this study, novel acrylated epoxidized hemp oil bioresin was used in the manufacturing of jute fibre reinforced biocomposites. The 100% biocomposite laminates were characterised in terms of mechanical properties (tensile, flexural, Charpy impact and interlaminar shear), thermo-mechanical properties (glass transition temperature, storage modulus and crosslink density) and water absorption properties (saturation moisture level and diffusion coefficient). Comparisons with the equivalent synthetic vinylester resin based jute fibre reinforced biocomposite panels were performed. Scanning electron microscopic analysis confirmed panel samples containing acrylated epoxidized hemp oil to display improved fibre–matrix interfacial adhesion compared with the vinylester resin based samples. Furthermore in terms of mechanical properties acrylated epoxidized hemp oil based biocomposites compared favourably with those manufactured from vinylester resin synthetic resin. Dynamic mechanical analysis found acrylated epoxidized hemp oil based biocomposites to have lower glass transition temperature, storage modulus and crosslink density than vinylester resin based samples. Increasing acrylated epoxidized hemp oil content resulted in a marginal increase in saturation moisture content and diffusion coefficient.