Particulate-filled Polymer Composites Research Articles

Storage Life of Particle-Filled Polymer Composites Considering Aging Effects.

This study investigates the storage life of particle-filled polymer composites (PFPCs) under the influence of aging effects. High-temperature accelerated aging tests were conducted at 60 °C, 70 °C, and 80 °C for various days to analyze the impact of aging time and temperature on the mechanical behavior of the materials. A predictive model for crosslink density was established using the Arrhenius equation, and the relationship between crosslink density and relaxation modulus was determined based on polymer physics theory. On this basis, a viscoelastic constitutive model that incorporates aging effects was developed. Structural analyses of a PFPC column with a length of 2.3 m and outer diameter of 1.8 m were performed using the UMAT subroutine in ABAQUS. Subsequently, a safety margin assessment method based on dewetting strain was employed to predict the storage life of the PFPC column. The results indicate that the aging viscoelastic constitutive model effectively characterizes the hardening effects caused by aging in the composites during storage. The storage life for the PFPC column considering aging effects decreases from 22 years to 19 years compared to models that ignore such effects. This approach provides a reference for estimating the storage life of PFPC columns considering aging effects.

Epoxy‐hemp and epoxy‐flax composites filled with glass dust for enhanced thermal insulation: An analytical and experimental study

AbstractThis article reports on an analytical and experimental investigation on the effects of fiber and filler reinforcement on the effective thermal conductivity (keff) of epoxy‐based composites. This research aims at enhancing the thermal insulation capability of fiber reinforced composites by adding an industrial waste, WGD (waste glass dust) as particulate filler. For this, an analytical model is proposed to estimate the keff values of particle filled polymer composites with and without fiber reinforcement. The results computed from the proposed correlations are then validated with some previously reported investigations. For an experimental validation, hemp and flax fiber reinforced epoxy based hybrid composites are fabricated with WGD as the fillers in varying weight fractions of 0 to 0.2. Effects of filler content on keff of fiber‐polymer systems are studied. Their keff are measured by a Unitherm Model 2022 instrument. It is found that the predicted and measured values are in good agreement. It is observed that the keff of the epoxy composites reduced from 0.359 to 0.297 W/m K with increase in the WGD weight fraction from 0 to 0.2. The keff of hybrid composites are also reduced by 27% and 15.53%, respectively, with 20 wt% addition of WGD.Highlights Hybridization of natural fiber based polymer composites. Utilization of waste glass dust as functional filler. Model development for heat conduction across hybrid composite system. Insulation capability enhancement of epoxy using fiber/filler reinforcements. Low cost thermal insulation materials using green materials and industry waste.

Prediction of Aging Performance of Particle-Filled Polymer Composites Based on RVE Model.

In this study, the aging performance of particle-filled polymer composites (PFPCs) under thermo-oxidative conditions was investigated on multiple scales. High-temperature-accelerated tests were conducted to analyze the effects of aging time and temperature. A representative volume element (RVE) model was established for the PFPCs using a random particle-filling algorithm. A predictive model for the crosslink density was conducted based on the closed-loop chain reaction of polymer oxidation. According to the theory of polymer physics, the relation between the crosslink density and matrix modulus was determined. The particle/matrix interface in the RVE model was represented by the cohesive zone model (CZM). The parameters of the CZM were determined by the inversion techniques. Then, a comprehensive multiscale RVE model was constructed, which was applied to predict the modulus and dewetting strain of the aged PFPCs. The predicted results show good agreement with the test results, which verifies the reliability of our model.

Effect of the alumina micro-particle sizes on the thermal conductivity and dynamic mechanical property of epoxy resin.

Epoxy thermal conductive adhesives with high thermal conductivity and dynamic mechanical properties are important thermally conductive materials for fabricating highly integrated electronic devices. In this paper, micro-Al2O3 is used as a thermally conductive filler for the epoxy resin composite and investigated the effect of micron-sized alumina particle size on the thermal conductivity and dynamic mechanical property of epoxy resin by the transient planar hot plate method and DMA (Dynamic mechanical analysis). The experimental results show that with the same amount of alumina filling, the thermal conductivity and Tg (glass transition temperature) of epoxy/Al2O3 composite material decrease with the increase of alumina particle size. The maximum thermal conductivity of the composite material is 0.679 (W/mK), while the energy storage modulus of epoxy/Al2O3 composite material increases with the increase of alumina particle size, and the maximum energy storage modulus of the composite material is 160MPa. Compared with pure epoxy resin, the thermal conductivity and energy storage modulus have increased by 2.7 and 3.2 times, respectively. The epoxy/Al2O3 composite was applied to the COB (Chips On Board) type LED package, and the substrate temperature of the LED dropped to the lowest after 1.5 hours of operation using EP-A5 composite, and the temperature was stabilized at 38.2°C, indicating that the addition of 5-micron alumina composite has the best heat dissipation in the COB type LED package. These results are critical for the implementation of particulate-filled polymer composites in practical applications because relaxed material specifications and handling procedures can be incorporated in production environments to improve efficiency.

Multi-Scale Model for the Aging Performance of Particle-Filled Polymer Composites.

In this study, we developed a novel multi-scale model to predict the aging performance of particle-filled polymer composites (PFPCs) under thermo-oxidative aging conditions. To investigate the aging behavior, high-temperature accelerated aging tests were conducted in combination with macroscopic and microscopic characterization. At the microscopic level, the crosslinking density of the polymer matrix is calculated using the closed-loop chain reaction of polymer oxidation. In addition, the theory of polymer physics was used to determine the relationship between crosslinking density and elastic modulus. Relationships between elastic modulus and dewetting strain were analyzed at the macroscopic level. Based on the observations and analyses, a multi-scale model was developed to predict the aging performance of PFPCs. The predicted results show good agreement with the test results, which verifies the reliability of the model.

Formation and Behavior of Residual Stresses in Particulate-Filled Polymer Composites with a Partially Crystalline Structure

Formation and Behavior of Residual Stresses in Particulate-Filled Polymer Composites with a Partially Crystalline Structure

Effect of particle morphology on mechanical behaviour of highly particle-filled composites

The mechanical behaviour and failure mechanism of highly particle-filled polymer composites (HPFPCs) with different particle morphologies over a wide range of strain rates (0.0001 /s to 1000 /s) and temperatures (-40°C to 100°C) are investigated using the nonlinear finite element method. The relevant micro-mechanical constitutive laws have been developed to characterize the mechanical performances of HPFPCs. The effects of particle shape and particle volume fraction (PVF) on the crack path and mechanical behaviour (peak strength and effective modulus) of HPFPCs are illustrated. Compared with the actual and circular particle shaped structures, the polygonal particle shaped structure shows the most stable crack path and possesses the highest peak strength and the lowest effective stiffness in corresponding PVF. It indicates that the fracture resistance of the polygonal particle shaped structure is better than the particle structure with smooth particle surfaces, especially when dealing with high strain rate problems. A sequence of failure mechanisms of HPFPCs with different particle morphologies can be observed. At higher strain rates of 100 /s and 1000 /s and lower temperatures of -40°C and -20°C, besides the interfacial debonding as the main crack path, the fracture of the extended binder filaments and the flow of small particles with extended binder matrix can be observed. While, at lower strain rates of 0.0001 /s and 0.001 /s and higher temperatures of 80°C and 100°C, micro-cracks are more scattered through the model as the binder matrix becomes more ductile. Besides, the effective stiffness is more sensitive to the particle shape at higher strain rates, while the peak strength becomes more sensitive to the particle shape at lower strain rates.

Modeling of toughening effect in rigid particulate-filled polymer composites by artificial intelligence: a review

Low fracture toughness is the Achilles heel of many polymers for practical application, particularly for long-term and special applications such as medical implants and critical part design. The toughening of polymers is a complicated process, and the toughening mechanisms in many composite systems have not yet been fully understood. Machine learning (ML) has emerged as a promising tool for modeling various complex systems in the field of materials science. In this respect, ML appears to be an effective, affordable, and accurate technique in the modeling of the toughening process. This review article provides an overview of the recent ML-based approach for analyzing toughening effects in rigid particulate-filled polymer composites. The results summarized here would contribute to further possibilities for researchers to explore emerging trends for designing toughing and high-performance polymers.

The Establishment of Thermal Conductivity Model for Linear Low-Density Polyethylene/Alumina Composites Considering the Interface Thermal Resistance.

An optimized thermal conductivity model of spherical particle-filled polymer composites considering the influence of interface layer was established based on the classic series and parallel models. ANSYS software was used to simulate the thermal transfer process. Meanwhile, linear low-density polyethylene/alumina (LLDPE/Al2O3) composites with different volume fractions and Al2O3 particle sizes were prepared with the continuous mixer, and the effects of Al2O3 particle size and volume fraction on the thermal conductivity of the composites were discussed. Finally, the test result of the thermal conductivity was analyzed and compared with ANSYS simulations and the model prediction. The results proved that the thermal conductivity model considering the influence of the interface layer could predict the thermal conductivity of LLDPE/Al2O3 composites more precisely.

Crystallization mechanism of micro flake Cu particle-filled poly(ethylene glycol) composites

Poly(ethylene glycol) (PEG) is used as phase change materials while the low thermal conductivity restricted the thermal storage efficiency. Incorporation of the metal particles (MPs) into PEG could enhance the thermal conductivity while the crystallization kinetic mechanism of the MP-filled PEG composites is altered. Flake MPs are characterized with layer structure and a large aspect ratio, while there are few research works related to the effect of flake MPs on the crystallization kinetic mechanism of flake MP-filled polymer composites. In this work, different micro flake copper (Cu) particles contents were introduced into the PEG matrix via the physical blending method. The Fourier transform infrared instrument (FT-IR) was used to characterize the chemical compatibility of the PEG/Cu composites. The differential scanning calorimetry (DSC) method was to characterize the crystalline kinetic mechanism of the micro flake Cu particle-filled polymer composites by using the isothermal model and non-isothermal model. It was found that the COC conformation of the confined PEG in the composites was altered, and more helical conformations were transferred from the zigzag conformations. The addition of the Cu particles in the PEG matrix enhanced the heterogeneous nucleation meantime hindered the diffusion of the PEG molecular chains. As a result, the crystallization rate of the PEG/Cu composites was optimized only when there was a middle Cu content in the PEG matrix (14.89 wt% in this work). Additionally, the PEG/Cu composites had 3D PEG crystal growth geometry in the isothermal crystallization process while the stronger dependence of the PEG crystal growth geometry on the temperature was found in the non-isothermal crystallization especially when the Cu amount was higher than 14.89 wt%.

Predicting the mechanical behaviour of highly particle-filled polymer composites using the nonlinear finite element method

Highly particle-filled polymer composites (HPFPCs) usually consist of stiff crystal particles, polymeric binder/matrix and the interfaces between the particles and the matrix. Unlike normal particle-filled composites, the particle filled ratio of HPFPCs can reach around 90% to 95% by weight, which makes it difficult to study the mechanical properties of HPFPCs by traditional schemes. To explore the mechanical performance of HPFPCs thoroughly, the influences of strain rate, temperature, interface properties (interface strength and fracture energy), and micro-structure (particle volume fraction (PVF) and particle distribution) on the fracture mechanisms have been systematically investigated using the nonlinear finite element method. A micro numerical scheme has been developed, including the development of mechanical constitutive models for each constituent of HPFPCs, and the generation of the micro-structural model with the PVF of over 90% using a Voronoi-modified method. The multiple failure events have been reproduced including the visco-elastic deformation, the fracture of the matrix, and interfacial debonding dominating the crack mode. The predicted results are in good agreement with the available experimental measurements and other numerical simulation results. This work provides a robust numerical tool to analyse the micro-mechanical behaviour of HPFPCs.

Formation and behavior of residual stresses in particulate-filled polymer composites with a partially crystalline structure

Formation and behavior of residual stresses in particulate-filled polymer composites with a partially crystalline structure

Enhanced electromechanical performance of natural rubber dielectric elastomers achieved by in situ synthesis of silver nanoparticles on TiO 2 nanoparticles

Dielectric elastomers (DEs) could transduce electrical energy to mechanical energy, but their applications are currently limited by the elevated driving voltages. To obtain satisfactory actuated strains at low voltages, titanate oxide@tannic acid-ferric ion@silver (labelled as TiO2@TA-Fe3+@Ag) satellite-structure nanoparticles were obtained in this study by in situ synthesis followed by incorporating the nanoparticles into natural rubber (NR) to prepare DE composites (denoted as TiO2@TA-Fe3+@Ag/NR). The presence of surface coating of TA-Fe3+ and Ag nanoparticles improved the electromechanical performance of TiO2@TA-Fe3+@Ag/NR composites. Among the samples, 30 wt% TiO2@TA-Fe3+@Ag/NR composite displayed a relatively high actuated strain of 9.09% at a relatively low electric field of 22.78 kV/mm. In sum, the green, facile, and cost-effective surface modification method looks promising for improving the electromechanical properties of particulate-filled polymer composites.

Factors affecting the solid particle erosion of environment pollutant and natural particulate filled polymer composites—A review

Solid particle erosion of polymer matrix composites filled with naturally available and environment pollutant fillers have not been studied to the same level as for metals or ceramics and is focus of the present study. In this article, review of the research associated with the erosion response of polymer composites is presented. Particulate polymer composites are employed extensively owing to their enhanced specific properties and tribological response. Particulate filler particles such as environmental pollutants and naturally available ones need to be effectively incorporated in utilitarian applications so as to reduce land fill burden issues and other specific problems. Nevertheless, adequate data is not available in review articles on the erosion of fillers that are environment pollutants and thereby an ample amount of research can be carried out in this regard. Erosion behavior of polymer composites in particular has gained a lot of attention among researches in the recent decade. Viability of incorporating various fillers in polymer matrix for erosion resistive applications needs to be assessed so that the potential of these composites can be well understood. Therefore in this study, erosion response of polymer composites reinforced with fillers is reviewed with a focus on input parameters (impact velocity, impingement angle and erodent properties) and material properties (density).

Poly(Butylene Terephthalate) Filled with Sb2O3 Nanoparticles: Effects of Particle Surface Treatment, Particle Size, Particle Morphology and Particle Loading on Mechanical Properties of Composites

Poor dispersion of nanoparticles in polymer matrix would limit the development and application of particulate-filled polymer composites. Therefore, the Sb2O3 nanoparticles were functionalized by a combination of cetyltrimethyl ammonium bromide (CTAB) and silane coupling agent KH-560 via water bath modification method so as to improve the dispersion of Sb2O3 nanoparticles in poly(butylene terephthalate) (PBT) matrix and enhance the interfacial adhesion between nanoparticles and polymer matrix. Besides, the coating efficiency of compound modifiers on the surface of Sb2O3 nanoparticles was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA). The Sb2O3 nanoparticles with different morphologies were systemically measured using transmission electron microscopy and dynamic light scattering measurement. The effects of particle surface treatment, particle size, particle morphology and particle loading on mechanical properties of composites were studied by the X-ray diffraction (XRD), tensile test machine and impact strength machine. The tensile strength of nanocomposites gradually increases with decreasing the particle size at the same amount of Sb2O3 nanoparticle fillers, which is attributed to improvement of interfacial contact area and stronger interfacial adhesion between Sb2O3 nanoparticles and PBT matrix. And the compound modified Sb2O3 nanoparticles are homogeneously dispersed in PBT matrix and play an important role in the properties enhancement. Moreover, taking consideration of the tensile and impact strengths, the optimal loading is 3 wt%.

Polyester composites filled with walnut shell powder: Preparation and thermal characterization

AbstractThis article reports on the fabrication and subsequently on the thermal properties of a biomaterial filled polymer composite consisting of polyester and walnut shell powder (WSP) in different proportions. The focus has been given to the evaluation of effective properties of the composites like thermal conductivity, glass transition temperature, and coefficient of thermal expansion. The experimental findings obtained for thermal conductivity are supported by the mathematical and numerical analysis made under suitable assumptions. A mathematical correlation is proposed to predict the effective thermal conductivity (Keff) of such particulate filled polymer composites. For the numerical study, a commercially available finite‐element package ANSYS19.2R2 is used to calculate the thermal conductivity of the composites. One dimensional heat conduction analysis is performed across composites with the periodic and randomly oriented arrangement of spherical fillers in different concentrations. Thermal conductivities of the composites are measured with Unitherm Model 2022 tester to validate the results. These values are then compared with effective thermal conductivities obtained from the proposed mathematical correlation and are found to be in close agreement with one another. It is concluded from this study that the addition of WSP improves the thermal insulation capability of neat polyester to a reasonable extent.

Thermal Analysis of Particulate Filled Polymer Composite

In the past few decades, a lot of experiments had been done to identify the thermal conductivity of particulate filled polymer composites. The trend had resulted in creation of increased thermal and mechanical properties particulate composites. In the present research work, the thermal conductivity of aluminium filled polymer composite was identified by three way approach, viz, experimental, analytical and finally by FEM – Ansys. Various filler concentration was taken and the thermal conductivity was identified for each unique case and the values were further compared with other methods for verifying the experimental data. The analysis shows that addition of aluminium particulates increases the thermal conductivity of the composites, thereby improving its heat transfer capability.

Global and local conductivity in percolating crosslinked carbon black/epoxy\u2013amine composites

Conductive particle-filled polymer composites are promising materials for applications where both the merits of polymer and conductivity are required. The electrical properties of such composites are controlled by the particle percolation network present in the polymeric matrix. In this study, the electrical properties of crosslinked carbon black–epoxy–amine (CB-EA) composites with various CB concentrations are studied at room temperature as a function of the AC frequency f. A transition at critical frequency fc from the DC plateau σDC to a frequency-dependent part was observed. Conductivity mechanisms for f > fc and f < fc were investigated. By considering the fractal nature, conduction for f > fc was verified to be intra-cluster charge diffusion. For f < fc, with the assistance of conductive atomic force microscopy (C-AFM), the conduction behavior of individual clusters can be observed, revealing both linear and nonlinear I–V characteristics. By combining microtoming and C-AFM measurements, 3D reconstructed images offer direct evidence that the percolating network of these materials consists of both a low-conductivity part, in which the charge transports through tunneling, and a high-conductivity part, which shows ohmic electrical properties. Nevertheless, for these CB-EA composites, the presence of these non-ohmic contacts still leads to Arrhenius-type behavior for the macroscopic conductivity.

Structure and calculation of filler content in particle-filled polymer composites in mass and volume units

The paper presents the data of calculations of the structure and composition of particle-filled polymer composites with various fillers and polymer matrices. It is shown that the parameters of the structure, the filler content of composite, as well as the dependencies of properties on the parameters of the structure should be presented only in volume units (vol. fractions or vol. %). Calculations of the compositions in mass units are allowed for the calculation of weighing in composites manufacturing.

Filler shape and volume fraction effect on dynamic compression behaviour of glass filler reinforced epoxy composites

The effect of filler shape and volume fraction on the dynamic compression behaviour of low volume fraction rigid particle filled polymer composites is demonstrated by performing experiments using s...