Thermal Behavior Of Composites Research Articles

The Structural, Thermal and Morphological Characterization of Polylactic Acid/Β-Tricalcium Phosphate (PLA/Β-TCP) Composites upon Immersion in SBF: A Comprehensive Analysis.

Biocomposite films based on PLA reinforced with different β-TCP contents (10%, 20%, and 25%wt.) were fabricated via solvent casting and immersed in SBF for 7, 14, and 21 days. The bioactivity, morphological, and thermal behavior of composites with immersion were studied using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) microanalysis, weight loss (WL), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). This broad analysis leads to a deeper understanding of the evolution of the polymer-filler interaction with the degradation of the biocomposites. The results showed that β-TCP gradually evolved into carbonated hydroxyapatite as the immersion time increased. This evolution affected the interaction of β-TCP with PLA. PLA and β-TCP interactions differed from PLA and carbonated hydroxyapatite interactions. It was observed that β-TCP inhibited PLA hydrolysis but accelerated the thermal degradation of the polymer. β-TCP retarded the cold crystallization of PLA and hindered its crystallinity. However, after immersion in SBF, particles accelerated the cold crystallization of PLA. Therefore, considering the evolution of β-TCP with immersion in SBF is crucial for an accurate analysis of the biocomposites' degradation. These findings enhance the comprehension of the degradation mechanism in PLA/β-TCP, which is valuable for predicting the degradation performance of PLA/β-TCP in medical applications.

Biomimetic Growth of Hydroxyapatite in Hybrid Polycaprolactone/Graphene Oxide Ultra-Porous Scaffolds.

This paper reports the preparation and characterization of hybrid scaffolds composed of polycaprolactone (PCL) and different graphene oxide (GO) amounts, intending to incorporate the intrinsic characteristics of their constituents, such as bioactivity and biocidal effect. These materials were fabricated by a solvent-casting/particulate leaching technique showing a bimodal porosity (macro and micro) that was around 90%. The highly interconnected scaffolds were immersed in a simulated body fluid, promoting the growth of a hydroxyapatite (HAp) layer, making them ideal candidates for bone tissue engineering. The growth kinetics of the HAp layer was influenced by the GO content, a remarkable result. Furthermore, as expected, the addition of GO neither significantly improves nor reduces the compressive modulus of PCL scaffolds. The thermal behavior of composites was investigated by differential scanning calorimetry, showing an increase in crystallinity as the addition of GO raised, which implies that GO nanosheets can act as seeds to induce the crystallization of PCL. The improved bioactivity was demonstrated by the deposition of an HAp layer on the surface of the scaffold with GO, especially with a 0.1% GO content.

Structural composite based on 3D printing polylactic acid/carbon fiber laminates (PLA/CFRC) as an alternative material for femoral stem prosthesis

In recent years, surgical procedures for hip prostheses have increased. These implants are manufactured with materials with high stiffness compared to the bone, causing bone loss or aseptic loosening. This research proposes an alternative structural composite consisting of 3D-printing polylactic acid layers and carbon fiber laminates (PLA/CFRC) with potential application in prosthetic implants. Fourier-transform infrared spectroscopy (FTIR) achieved to characterize starting materials and structural composites revealed secondary chemical interactions between the carbonyl group of PLA with the hydroxyl group of epoxy resin from CFRC. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results show both components (PLA and CFRC) influence the structural composite's thermal behavior, observed in the temperatures of degradation, glass transition, and melting. Furthermore, the composite reached cell viability above 80%, a tensile modulus of 19.29 ± 0.48 GPa and tensile strength of 238.91 ± 25.95 MPa, with mechanical properties very similar to the bone. The results of this study demonstrated that the proposed PLA/CFRC composite can be used as candidate base material for the manufacturing of a hip femoral stem prostheses.

Mechanical and Thermal Characteristics of Hybrid Composites Fortified with Flax, Banyan, and Glass Fibers for Automobile Safety Applications

ABSTRACT Automobile sector is growing day by day due to the globalization and the urbanization. Further, the luxury life of human beings leads to the new development in the production of automobiles. Consumers are looking for fuel economy with safety features in automobiles. Hence, the weight reduction and strength performance of components play major role in manufacturing of automobiles. In this current investigation, we tried to develop new composite materials with light weight and better thermal and mechanical characteristics using natural and synthetic fibers. Totally, six types of composites were manufactured, namely, Epoxy/Banyan, Epoxy/Glass, Epoxy/Flax, Epoxy/Banyan/Flax, Epoxy/Banyan/Glass, and Epoxy/Flax/Glass by conventional hand layup method by keeping matrix-to-fiber ratio as 60:40. Mechanical and thermal characteristics of the composites were examined. Based on the thermal behavior of composites, Epoxy/Banyan composite was selected as the suitable candidate for thermal insulation applications in automobile industries as exhibited least thermal conductivity of 0.112 W/mK. Further, the mechanical characteristics were tested for Epoxy/Banyan composite. Results displayed the properties as: tensile strength − 75 MPa; flexural strength − 113 MPa; impact strength − 12.8 kJ/m2.

Experimental Investigation on Thermal Behaviors of Nanosilicon Carbide/Kenaf/Polymer Composite

Over the last few years, natural fiber‐based hybrid polymers have been widely used to increase the biodegradability and cost‐effectiveness of the products in many industrial applications, such as automobile construction industries. Adding filler materials provides enhanced wear properties and thermal behaviors of composites. Kenaf fiber has better strength and stiffness, and it has been used as reinforcement in polymer composites. Silicon carbide as filler material in composites modifies the mechanical properties and thermal behaviors. The present research analyzes the thermal characteristics of silicon carbide/kenaf fiber‐reinforced epoxy composites with various weight percentages. Six different composite specimens were fabricated at varying weight percentages of silicon carbide. The specimens were subjected to various thermal tests, such as heat deflection temperature (HDT), coefficient of thermal expansion (CTE), thermal conductivity (TC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The findings could serve to expand the range of application for SiC/kenaf fiber‐reinforced composite, which may have better thermal stability, better performance, and lower thermal expansion than the other regularly used natural fiber‐reinforced composites.

Property Correlations of Polypropylene based Composites Filled with Mimusop elengi Seed Shell Powder

The saturation point of Mimusop elengi seed shell powder (MESSP) and the effect of MESSP addition on the mechanical, thermal, water absorption and morphological properties of polypropylene (PP) composites were studied. Tensile fracture, physio-mechanical properties and thermal behavior of composites were characterized using tensile and impact testing, thermogravimetric analysis, scanning electron micrograph, and differential scanning calorimetry. Processability of composites were feasible up to 20 wt. % MESSP by which agglomeration of MESSP and poor dispersion of MESSP in PP was observed above 20 wt% MESSP loading. Increasing MESSP loading showed tremendous improvement in tensile modulus and impact strength, whereas tensile strength and elongation at break were reduced. Water absorption and thermal decomposition of composites remain comparable with addition of MESSP up to 20 wt. %. Reduction of tensile strength was attributed by weak adhesion between MESSP and PP. However, morphological analysis revealed the presence of physical interaction via PP chain interlocking on MESSP surface.

N-eicosane/multilayer graphene composite phase change materials for electro-thermal conversion and storage

Phase change materials (PCMs) have many promising potentials for thermal energy conversion, storage, and utilization. However, several technical bottlenecks must to be solved such as poor thermal conductivity and leakage of liquid during the phase transition process. In this work, the n-eicosane (C20) was incorporated into the multilayer graphene (MLG), and the C20/MLG composite PCMs were fabricated through vacuum impregnation. The chemical stability, microstructure, and thermal behaviors of composites were characterized in detail. The DSC analysis shown that the C20/MLG composites have a latent heat value of 136.6–212.5 J g−1 for melting with excellent crystallinity over 98%. The influence of MLG on thermal behavior was investigated and discussed. By adding 45 wt% MLG, the thermal conductivity of C20/MLG45 (1.112 W m−1 K−1) was 4.85 times that of C20 (0.289 W m−1 K−1), and the thermal storage and release plots indicated the MLG considerably promoted the heat transfer performance of composites. The outstanding transient temperature response of C20/MLG45 was recorded by the thermal infrared imager. Moreover, the C20/MLG45 can effectively convert electricity to latent heat. The results of electro-thermal conversion measurement shown the electro-latent heat storage efficiency of C20/MLG45 can exceed 59.9% at 1.9 V. In conclusion, the composite C20/MLG45 have potentials in thermal energy storage applications including electro-thermal conversion and storage, building energy conservation and electrical power peak shifting.

Numerical Simulation of Thermal Diffusivity Measurements With the Laser-Flash Method to Evaluate the Effective Property of Composite Materials

Abstract The laser-flash method (LFM) is a technique commonly used to measure thermal diffusivity of homogeneous and isotropic materials, but can also be applied to macroscopically inhomogeneous materials, such as composites. When composites present thermal anisotropy, as fiber-reinforced, LFM can be used to measure the effective thermal diffusivity (αeff) in the direction of heat flux. In this work, the thermal behavior of composites during thermal diffusivity measurements with the LFM was simulated with a finite element model (FEM) using a commercial software. Three composite structures were considered: sandwich layered (layers arranged in series or parallel), fiber-reinforced composites, and particle composite (spheres). Numerical data were processed through a nonlinear least-square fitting (NL-LSF) to obtain the effective thermal diffusivity of the composite. This value has the meaning of “dynamic effective thermal diffusivity.” Afterward, the effective thermal conductivity (λeff) is calculated from the dynamic effective thermal diffusivity, equivalent heat capacity, and density of the composite. The results of this methodology are compared with the analytically calculated values of the same quantity. This last assumes the meaning of “static effective thermal conductivity.” The comparison of the dynamic and static property values is so related to the inhomogeneity of the samples, and a deviation of the temperature versus time trend from the analytical solution for the perfectly homogeneous sample gives information about the lack of uniformity of the sample.

Studies on mechanical and thermal performance of carbon nanotubes/polypropylene nanocomposites

Multi wall carbon nanotube (MWCNTs) reinforced Polypropylene (PP) composites are fabricated by compression molding machine. Composites are prepared with 0.4, 0.8, 1.2 and 1.5 wt% of Multi wall carbon nanotube as nanofiller in polypropylene matrix. Mechanical and thermal behavior of composites is examined as per ASTM. Results shows improvement in mechanical and thermal properties due to addition of Multi wall carbon nanotube in Polypropylene matrix. Tensile strength was highest at 62.80% at 1.2 wt%. Impact strength and hardness is improved by 82.14% and 12.44% at 1.5 wt%. Glass transition temperature was increased at low wt. % and further decreases. The SEM images of composite implied that MWCNTs have dispersed uniform in Polypropylene (PP) matrix reasons for property enhancement. These composites find application in plastic products and furniture.

Study on biodegradability and thermal behaviour of composites using poly lactic acid and gamma-irradiated fibres of Luffa cylindrica

Surface modification of natural fibres by gamma irradiation is an economical and potent technique. The biodegradability of gamma irradiated Luffa cylindrica (LC) fibres having response of doses (0.5Gy, 1Gy and 2Gy) is studied. The degradation process is carried out in various environments like compost, sand, soil, salt water, brackish water and sweet water for a period of 90 days and microbial degradation using bacteria and fungi for a period of 90 days. The rate of biodegradation was calculated by measuring the loss of weight of composites at an interval of 30 days in each environmental condition. Preliminary results reported that the bacterial environment was the most prominent medium for degradation than fungi. B8 composites showed degradation of 27.5% and 3.59 in bacterial and fungal medium respectively. A minimum degradation was observed in compost medium (0.29%, 2.52%, 0.21%, 0.08%, 0.11%, 0.13%, 0.17%, 1.25% and 1.51% for B1–B9 respectively). For exploring the use of the composites in the field of biomedical sciences, the LC fibres are modified using calcium salts before reinforcement. The thermal properties like crystallization temperature (Tcc), glass transition temperature (Tg), melting peak temperature (Tm) and thermal stability of the bio-composites were analyzed using Differential scanning calorimetry (DSC) in temperature range from 30 °C to 250 °C and the thermogravimetric analysis (TGA) was done in the temperature range of 20 °C to 700 °C. With increase in irradiation dose, crystallization temperature and glass transition temperature increased. Increasing in the irradiation dose, thermal stability of the composites decreased.

Mechanical, Wear and Thermal Behaviors of Graphene Reinforced Titanium Composites

In this study, the effects of graphene content (0.15, 0.30, 0.45 and 0.60 wt%) on the mechanical, tribological and thermal properties of titanium matrix composites were investigated. The experimental results showed that the highest ultimate compressive strength (845 MPa), tensile strength (613 MPa), lowest mass loss (0.6 mg for 10 N), and lowest wear rate (WR = 286 × 10−5 mm3/Nm for10 N) were obtained for Ti-0.15GNPs compared with pure titanium (652 MPa, 413 MPa, 1 mg and 5 × 10−5 mm3/Nm, respectively). The wear rate of composites deteriorates with increasing applied load. From the thermal analysis results, the best thermal conductivity (16 W/mK) and diffusivity (7.1 mm2/s) were performed for Ti-0.30GNPs composites at room temperature. The thermal behavior of the composites was decreased with increasing graphene content and temperature. It concluded that graphene is an effective reinforcement to develop the mechanical, wear and thermal behavior of titanium matrix composites.

Polycaprolactone/Graphene Nanocomposites: Synthesis, Characterization and Mechanical Properties of Electrospun Nanofibers

In this study, three polymer nanocomposites based on poly(e-caprolactone) (PCL) grafted on the graphene quantum dot (GQD), hydroxypropyl cellulose (HPC)/GQD (GQD: HPC = 1:1; w/w) and graphene oxide (GO) with 1.6 wt% of e-caprolactone (CL) were synthesized via in situ ring opening polymerization of CL. The synthesized nanocomposites were characterized using FTIR, 1H NMR, and contact angle measurements. The lowest molecular weight for PCL/GO was obtained according to 1H NMR spectra. Crystalline structure and thermal behavior of composites were investigated by XRD, DSC and TGA. The results showed that the presence of HPC and graphene-based nanofillers in nanocomposite can affect the hydrogen bonding interaction with PCL chains, melting temperature (Tm), degree of crystallinity [Xc(%)] and the size of crystals. According to the results, PCL/GQD-HPC had higher Tm, lower Xc(%), longer PCL moieties and smaller crystals. Also, the TGA results indicated that the nanocomposites were thermally more stable than the pure PCL. Moreover, a conventional electrospinning process was used to prepare nanofibers of synthesized nanocomposites blended with PCL (50:50; w/w). SEM images and mechanical behavior study of obtained nanofibers depicted that the PCL/(PCL/GQD-HPC) nanofibers have a significant increment in the average diameter, tensile modulus and strength in comparison with other composites.

Structural study and thermal behavior of composites: Polyamide 66/glass fibers: The reinforcement ratio effect on the kinetics of crystallization

The present research aims at studying the kinetics of non-isothermal crystallization of the polyamide 66 matrix and its composites with the presence of a glass fiber load. To achieve that goal, the non-isothermal crystallization of polyamide 66 has been studied by means of DSC. The ratio of tested reinforcement varies from 7% to 50% of glass fiber in mass. The modeling, by the theories of Jeziorny and those of Mo, has allowed us to study the influence of adding this reinforcement, as well as the variation of the rate of cooling, on the kinetics of crystallization of the composites in question, which has been manifested by a remarkable change in the nucleation mechanism of the polyamide 66 matrix. Regarding the reinforcement effect, the incorporation of the glass fibers load into the polyamide 66 matrix has caused the appearance of exothermic peaks in a higher temperature range and that for all the working materials. Finally, the results showed that the Mo model is the most suitable for the study of polyamide 66/glass fiber crystallization kinetics.

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

Higher order two-scale finite element error analysis for thermoelastic problem in quasi-periodic perforated structure

In this paper, one new coupled higher order two-scale finite element method (TSFEM) for thermoelastic problem in composites is proposed. Firstly, some new two-scale asymptotic expressions and homogenization formulations for the problem are briefly given. Next, some high–low coupled approximate errors corresponding to TSFEM are analyzed. Finally, some numerical results of the displacement and the increment of temperature are presented, which show that TSFEM is an effective method for predicting the mechanical and the thermal behavior of composites in quasi-periodic perforated structure.

Cationization of cellulose fibers for composites

In this work, composites were made by improved bonding of the cationized cellulosic fabric and some anionic matrix like Carboxymethyl Cellulose (CMC). Mercerized cotton fabric was cationized using cationization agent, TEXAMIN ECE with varying percentage from 1 to 10%. Those cationized cotton samples were incorporated in anionic matrices and the resultant composites were tested for mechanical properties on Universal Textile Tensile Testing machine. In the case of CMC as the matrix for the cationized reinforcement, the increasing trend in the tensile strength and elongation at break was observed. Scanning Electron Microscope images showed no extraordinary changes in the physical appearance of the cationized samples. Thermograms derived from Differential Scanning Calorimetry were informative for the evaluation of the thermal behavior of composites.

Characterisation of mechanical and thermal properties in flax fabric reinforced geopolymer composites

This paper presents the mechanical and thermal properties of flax fabric reinforced fly ash based geopolymer composites. Geopolymer composites reinforced with 2.4, 3.0 and 4.1 wt% woven flax fabric in various layers were fabricated using a hand lay-up technique and tested for mechanical properties such as flexural strength, flexural modulus, compressive strength, hardness, and fracture toughness. All mechanical properties were improved by increasing the flax fibre contents, and showed superior mechanical properties over a pure geopolymer matrix. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies were carried out to evaluate the composition and fracture surfaces of geopolymer and geopolymer/flax composites. The thermal behaviour of composites was studied by thermogravimetric analysis (TGA) and the results showed significant degradation of flax fibres at 300 °C.

Recycling of textile waste into green composites: Performance characterization

Recycling of any waste is as such a worldwide phenomenon. In this context application of textile waste for development of some value added product has been thought of in this work. Textile fabric waste is collected from various sources. These waste materials are garneted, so as to produce loose fibrous material. Subsequently this fibrous material was converted into nonwoven web and also twisted strand for manufacturing of 3D woven preforms to be used in composites. In case of nonwoven preforms, the webs are produced by combining polypropylene with cotton component with different proportions. Composites of various specifications are developed to examine their application in several end uses. These composite materials are characterized for their mechanical and thermal behavior in order to find out the response against tensile loading, impact force and thermal loading. The effects of moisture absorption on mechanical properties of these composites are investigated. As the percentage of PP fibres is increased in the web, mechanical performance of the composite material is improved in general. The exposure of composite material to high humidity condition has not shown any significant change in their mechanical behavior. 3D woven fabric reinforced composite produced by using garneted fibre yarn and virgin cotton OE yarn didn't exhibit any significant difference in the mechanical and thermal behavior of composite. The results confirmed that textile waste material can be safely used as reinforcing structure in composite manufacturing. POLYM. COMPOS., 35:1960–1967, 2014. © 2014 Society of Plastics Engineers

Hydroxyapatite Nanocomposites for Biological Application

Hydroxyapatite is a bioceramic which has a wide range of medical application for bone diseases. To enhance its usage, we have prepared ciprofloxacin loaded nanohydroxyapatite (HA) composite with a natural polymer, alginate, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods. The results show that the nanoHA crystallites are well intact with the alginate macromolecules. For the composite system FT-IR study is done. The drug is pre-adsorbed onto the ceramic particle before the formation of composite. The thermal behavior of composite has been studied using thermo gravimetric analysis (TGA). This paper communicated the Influence of Polymer concentration on the Controlled drug release from hydroxyapatite Nanocomposites

Thermal and mechanical characterization of polypropylene/eggshell biocomposites

This study extends a work started on the new bio-composite materials; polymer/eggshell composites. Polypropylene/chicken eggshell composites were chosen and prepared via melt extrusion. The mechanical and thermal behavior of composites containing 10–40 wt% of untreated and strearic acid-treated eggshell were studied. The results show improvements in tensile modulus of composites while the values of tensile strength, strain at break, and impact strength decrease compared to that of neat polypropylene. The crystallization temperature, Tc, is clearly increased by incorporating 10 wt.% eggshell into polypropylene while a margin effect on the degree of crystallinity is seen. It can be concluded that composites need to be further studied and modified for possible use of eggshell as filler without scarifying the mechanical properties of the neat polymer matrix.