Increasing Filler Content Research Articles

Mechanical and wear behaviour of graphite nano filler reinforced Al 6061 composites

In this present work Aluminium 6061-Graphite Nano filler composites are developed with varying percentages of Graphite Nano filler. The Aluminium 6061-Nano Graphite composites are prepared by hot extrusion method. The mechanical properties such as Tensile strength, Compressive strength and Hardness is studied experimentally. The wear behavior of the developed composites is studied using a Pin-On-Disc tester. Experimental results reveal there is considerable growth in Tensile strength as well as Hardness with the increase in Nano-Graphite filler content. Also, it is observed that the strength of the nano-graphite/Al 6061 composite is very good compared unreinforced Aluminium 6061. There is increase in wear resistance of the developed composites with increase in Nano-Graphite filler content. The improvements in properties are attributed to uniform dispersion of Nano-Graphite0filler and good interfacial bonding between Nano-Graphite filler and Aluminium 6061 matrix. The fracture study shows the transition of ductile fracture in case of pure Alumunium 6061 to Brittle fracture in Aluminium 6061-nano Graphite composites.

Effect of particle size on physical properties of epoxy composites filled with micro-size walnut shell particulates

Polymers filled with bio-particulates are replacing the plastic component to achieve the environmental sustainability. Given this, present work comprises of developing composites prepared by reinforcing walnut shell powder (WSP) as bio-particulates in epoxy matrix. The filler used in present work has varied size i.e. 50 µm, 75 µm and 100 µm. Three different sets of composites are fabricated using hand lay-up method with three different sizes of particles. In each set, composites are fabricated for four different filler loading i.e. 5 wt%, 10 wt%, 15 wt% and 20 wt%. The effect of particle content and size of WSP on different physical properties is studied. The properties under investigation are density, void content and water absorption rate. From the experimental investigation, it has been seen that, both the parameters i.e. filler size and its content has noticeable impact on the physical properties. It is observed that with increase in filler content, density of the composite decreases whereas void content and water absorption rate increases. Further, it is noted that, composites with large particle size WSP has low density, high void content and greater water absorption rate as compared to the composites with small particle size WSP.

Development and characterization of walnut/vinyl ester filled homogeneous and their functionally graded composites

The work carried in the present study deals with the physical and mechanical characterization of walnut filled-vinyl ester composite prepared by gravity die casting and centrifugal casting (functionally graded materials). Among the physical and mechanical properties, void content, hardness, flexural strength, and impact energy in the case of functionally graded materials (FGMs) are found to boost with the increase in filler content. In contrast, tensile strength was found to deteriorate for FGMs as compared to homogeneous and neat composites. Pin-on-disc (POD) machine was used to evluatethe sliding wear performance of the fabricated composites of both types under specific humidity and thermal conditions The overall result shows that the wear rate of FGM composites is comparatively lower than GDC composites.

Synthesis and properties of Sulphonated Polystyrene, Their New Composites and IPNs

Sulfonated polystyrene (SPS) is a polyelectrolyte solid that is widely used in many applications. In this study, the sulfonation reaction of food packages polystyrene (PS) waste was done using sulfuric acid as a sulfonation agent, with the variation of concentration and times. The degree of sulphonation was determined. Composite from SPS and two types of fillers (carbon black and Nano silica) were synthesized, and new IPNs between SPS and phenolic resin type novolac was prepared. The characterization of the sulfonated product and its IPNs have covered functional groups' analysis using FTIR spectrophotometers. On the other hand, tensile and modulus of the SPS composites were determined, and the results showed that the tensile strength and modulus was increase with increasing filler content ( 0.48 Map for SPS alone to 1.051 Map when the percentage of Nano silica 7% ) while the modulus was increase from 0.527 Map for SPS alone to 1.272 Map when the percentage of Nano silica 7% , The same results obtained in the case of carbon black as filler .Water absorption of the prepared thin films for SPS was more than PS alone due to the effect of the presence of polar sulphonic group in their polymer chains . Thermal behavior of SPS and their IPNs also studied and evaluated using TGA and DSC techniques; the results show that the decomposition temperature was more than 300 oC

Mechanical properties of epoxy composites filled with micro-sized kota stone dust

Present work evaluates the potential of Kota stone dust as filler material in the epoxy matrix. Kota stone dust obtained from Kota stone industry located in Rajasthan, India. In this paper, epoxy-based composite fabricated using Kota stone dust as filler material using hand lay-up method. The dust was collected from the construction site and sieved to gather particles of 75µm size. Composites fabricated with varying content of fillers ranges from 10 wt% to 40 wt%. The effect of varying weight percentage of Kota stone dust particles on various mechanical properties was investigated and reported. It was noticed that the incorporation of Kota stone dust in epoxy matrix improves the mechanical properties of the developed material. As the filler content increases, remarkable enhancement in hardness and compressive strength of the material is received. Again, improvement in tensile and flexural properties has noticed for a given limit of filler content.

Difunctional composite coatings with low infrared emissivity and electrostatic dissipation property

The functional coatings play a critical role in many fields. To obtain difunctional composite coatings with low infrared emissivity and electrostatic dissipation (ESD) property, the composite coatings reinforced by aluminum-doped zinc oxide (AZO) and ESD carbonaceous fiber (CF) hybrid pigments were prepared, which were characterized by X-ray diffraction, scanning electron microscopy, infrared emissometer and insulation resistance tester. The effects of Al doping ratio of AZO, pigment adding amount and pigment type on the infrared emissivity and surface resistivity of the composite coating have been studied. The results confirmed that AZO of 7at.% doping concentration has lower infrared emissivity, and the infrared emissivity of AZO and CF coatings decreases with the increase of filler content. When AZO and CF are mixed at 1:1, the surface resistivity of the coating is 6380 Ω, which is much lower than that of any single pigment coating. Their synergy effect was contributed to form a continuous conductive path in the coating, enhance the tunnel current and obtain low surface resistivity for electrostatic dissipation. This work provides a new strategy for developing difunctional composite coatings with low infrared emissivity and electrostatic dissipation property.

Analysis of Long-Term Performance and Snowmelt Capacity of Anti-Freezing Asphalt Pavement

Abstract Anti-Freezing Asphalt Pavement (AFAP) has good snow-melting performance and is used widely in many countries around the world. The objective of this study was to analyze AFAP’s long-term performance and predict its snow-melting ability. Two types of anti-freezing stone matrix asphalt (SMA) mixtures (SMA-13 with Iceguard and SMA-13 with Mafilon) were prepared with the Marshall method. Water stability, high-temperature stability, low-temperature crack resistance, and freeze-thaw split tests were conducted to evaluate mixtures’ performance. Meanwhile, the effect of anti-freezing filler, asphalt content, and soaking temperature on the salt dissolution of anti-freezing asphalt mixtures was analyzed, and the snow-melting ability of AFAP was predicted based on the Back Propagation (BP) neural network. The results illustrated that water stability of anti-icing asphalt mixture reduced, and the dynamic stability after short-term aging was improved. The tensile strain and tensile strength ratio of the anti-icing asphalt mixture reduced after long-term aging and soaking in water. In addition, the salt dissolution rate increased with the increase of anti-freezing filler content and the decrease of asphalt content. The research conducted suggests that the BP Neural Network can be utilized to predict the snow-melting ability of the anti-freezing asphalt mixture, and the regression coefficient of the predicted and measured salt dissolution was higher.

Thermophysical features of nanostructured polymer system based on polyurethane

Polymer systems containing nanoparticles are new class of polymer composite materials. Polymer matrix filling influences on network polymer structure forming mechanism. The filler influence appears in formation features of the network structure both near the filler surface and in polymer matrix volume. Polymer solid surface (filler, substrate, etc.) interaction results in polymer chains movement restriction, that in fact is equivalent of additional polymer network physical knots formation. The polymer – filler interface presence may lead to both increasing of physical polymer knots average amount and decreasing it because of decreasing the polymer –polymer type physical bonds amount. This in turn determines strength of the polymer composite value. Polyurethane composite filled with different type of gypsum has been studied. The semi-aquatic gypsum (water suspension and dry powder) and two-aquatic gypsum water suspension were used as the filler. The polyurethane oligomer was used as reactive polymer matrix. Thermal-and-physical properties of polymer composites were studied by differential scanning calorimetry. It is found that the semi-aquatic gypsum does not transform in two-aquatic gypsum within polymer matrix during observation time. Evidently, the first – the polymer matrix doesn’t have continues pores and the second – the polymer matrix forms dense surface layer that hinders the diffusion of water vapor to the filler. Obtained polymer compositions glass temperature shows weak dependence on gypsum concentration and method of gypsum filling, but shows strong dependence on heating multiplicity. Polymer composition change in heat capacity upon glass transition value ∆Cp decreases with filler concentration increases and strongly depends on filling process. To obtain stable material properties the annealing of internal strength is needed to carry out. Key words: polyurethane composite, gypsum, thermal-and-physical properties.

Analytical model for the transient permittivity of uncured TiO 2 whisker/liquid silicone rubber composites under an AC electric field

The electric field grading of dielectric permittivity gradient devices is an effective way of enhancing their insulation properties. The in-situ electric field-driven assembly is an advanced method for the fabrication of insulation devices with adaptive permittivity gradients, however, there is no theoretical guidance for design. In this work, an analytical model with a time constant is developed to determine the transient permittivity of uncured composites under an applied AC electric field. This model is based on optical image and dielectric permittivity monitoring, which avoids the direct processing of complex electrodynamics. For a composite with given components, the increased filler content and electric field strength can accelerate the transient process. Compared with the finite element method (FEM) based on differential equations, this statistical model is simple but efficient, and can be applied to any low-viscosity uncured composites, which may contain multiple fillers. More importantly, when a voltage is applied to an uncured composite insulating device, the proposed model can be used to analyse the spatiotemporal permittivity characteristics of this device and optimise its permittivity gradient for electric field grading.

Graphite reinforced silane crosslinked high density polyethylene: The effect of filler loading on the thermal and mechanical properties

AbstractCrosslinked polyethylene is a promising polymer regarding its mechanical properties and wear resistance, predominantly used in pipework systems. However, it suffers from low thermal conductivity, which limits its application in geothermal heating/cooling systems. In this work, crosslinked high‐density polyethylene (PEX) composites with spherical graphite (SG) as a reinforcing filler are examined in terms of their thermal and mechanical properties. Thermal conductivity measurements showed a significant improvement of the thermal conductivity of PEX with increasing filler content (40.6% augmentation for 5 wt% SG content), while the experimental data are in good agreement with the Chauhan theoretical model for spherical particles. Tensile tests revealed that the elastic modulus of PEX/SG composites presented a considerable improvement (23.6% augmentation for 5 wt% SG content). Various micromechanical models for the prediction of the composites' elastic behavior were applied to the experimental data, which present a satisfactory agreement with the Takayanagi I two‐phase model for low concentrations of SG, and the Takayanagi II two‐phase model for higher filler content.

Sawdust reinforced polybenzoxazine composites: Thermal and structural properties

In this study, Mangifera Indica tree sawdust reinforced bisphenol-A aniline based benzoxazine composites were prepared by varying the sawdust from 20 wt% to 45 wt%. Thermogravimetric analysis of composites revealed excellent compatibility between polybenzoxazine and sawdust from the remarkable growth in char yield from 22% (neat resin) to 36% (for highly filled) and glass transition temperature from 151 to 165°C. Ultimate weight loss of the composites evaluated from the Derivatives of TG plots. Limiting oxygen index values of the composites reported considerable growth i.e., from 28 to 32 along with the increase in filler content. Differential scanning calorimetry results showed that sawdust particles have an insignificant effect on curing temperature (219°C) for the raise in sawdust content. Structure of the sawdust, benzoxazine monomer, polybenzoxazine and composites were studied using Fourier transformation infrared spectroscopy. Overall, polybenzoxazine composites with sawdust as filler showed improved thermal properties when compared with pure polybenzoxazine.

Creep and Stress Relaxation Behaviour of Rice Husk Reinforced Low Density Polyethylene Composites

The creep and stress relaxation behavior of rice husk reinforced low density polyethylene composite was analyzed in this study. The exponential and power model were used to study the creep while the stress relaxation assessed the time required for the composites to maintain a certain strain level. The creep strain increased with increase in time, at various temperatures, with its highest creep at 70oC while the lowest is at 30oC, the power model provided an excellent fit than other models with a coefficient of determination of 0.9977 at 30oC, the neat low density polyethylene had a good stress relaxation behavior with 4.95 seconds for it to decay and subsequently decreased with increase in filler concentration.

Hydrophobic nanocomposites of PBAT with Cl‐fn‐POSS nanofiller as compostable food packaging films

AbstractAntibacterial nanocomposite films of poly(butylene adipate‐co‐terephthalate) (PBAT) incorporated with different weight percentage of octakis(3‐chloropropyl)octasilsesquioxane (chloropropyl functionalized POSS [Cl‐fn‐POSS]) nanofiller were prepared. The mechanical, thermal, morphological, barrier, and antimicrobial properties were examined. The mechanical properties of the nanocomposite films were enhanced by the addition of Cl‐fn‐POSS nanofiller. An optimum filler loading of 3 wt% is identified to be best suited for maximum enhancement in tensile strength (24 MPa for 3 wt% filled PBAT vs 11 MPa for neat PBAT) while a 1 wt% filler loading was adequate to double the tensile strength. The barrier properties (WVTR and oxygen transmission rate) of PBAT was improved by the presence of Cl‐fn‐POSS. A volume of 3 wt% filler loading results in 50% reduction of water permeation and 10% reduction in oxygen transmission. The thermogravimetric analyses of the nanocomposites indicated that the filler enabled the enhancement of thermal stability of PBAT. The nanocomposite films revealed antimicrobial activity with this activity increasing with increasing filler content. PBAT is compostable under suitable conditions and with a low weight percentage of filler that is largely made of silicon dioxide these nanocomposite films can find application as biodegradable food packaging material given their flexibility.

Effect of micro‐sized marble dust on mechanical and thermo‐mechanical properties of needle‐punched nonwoven jute fiber reinforced polymer composites

AbstractThis work explores effectiveness of marble dust as a filler in needle‐punch nonwoven jute fiber reinforced polymer composites, prepared through vacuum‐assisted resin transfer molding process. Four different particulate filled composites are fabricated by varying the filler percentage from 0 to 24 wt% at an interval of 8 wt% marble dust under the controlled environment. The mechanical characterizations such as flexural strength, interlaminar shear strength, compressive strength, and impact strength enhanced with the increase in filler wt% in the composite. The improvement rate is observed from 14% to 33% compared to the unfilled composite. However, for tensile strength is concerned with the increase in filler content in the composites, the strength shows declined in order irrespective of filler content. This study also focuses on high‐temperature applications, for that dynamic mechanical analysis is performed in a three‐point bending mode with 1 Hz frequency as a function of temperature. Similarly, in case of fracture toughness of the proposed composites, the fracture toughness increases approximately from ≈22%, 27% and 59% respectively over unfilled composite with the change in filler percentage. Simultaneously, numerical simulation for fracture toughness is also performed and compared with experimental results. The deviation is found in the range from 0% to 4% with R2 value of 0.984. Based upon the outcome of present results, this research work can be subsequently extended for the low‐grade housing applications in one end and at the same time, optimal waste utilization can also be possible to reduce the environmental waste.

The particle size effect of rice husk on thermal conductivity and dielectric constant of RTV Silicon rice husk composites

The rice husk (RH) is a wide agricultural resource by-product of rice milling process in Iraq. In this work, RH is used as filler to modified thermal conductivity and dielectric constant of RTV silicone. RH-RTV silicone composites are prepared with different RH filler particle sizes, they are equal to 6.5mm (raw RH), 1.18mm, 250 μm, 125 μm, 75 μm, and 50μm. The levels of RH filler loading (1, 3, 5, 7, 10, 15 and 20) (wt %). The thermal conductivity and dielectric constant of all RH-RTV silicone composites are studied. The effect of varying frequency (from 500 Hz to 1 MHz) on dielectric constant all composites is studied. The thermal conductivity of RH-RTV silicone composites decrease with RH filler concentration increases and particle size decreases, thermal conductivity has minimum value at 20%wt. The particle size effect on thermal conductivity of composite is very observably at 50μm particle. The dielectric constant of RH-RTV silicone composites is increased when RH filler concentration increases and particle size decreases, thy have maximum value at 20%wt and 50μm RH particle. The varying of frequency is low effect on 50μm RH-RTV silicone composites.

Effect of Groundnut Shell Particulate Content on Physical and Mechanical Behavior of Jute–Epoxy Hybrid Composite

This paper reports on the fabrication and characterization of some important physical and mechanical properties of an agro-waste-filled hybrid polymer composite consisting of epoxy, jute fabrics and groundnut shell powder in different proportions. The epoxy composites are fabricated with the reinforcement of groundnut shell particulate filler by varying the weight proportions (0, 5, 10, 15 and 20 wt%) and jute fabrics with constant fiber loading of 30 wt%. Physical and mechanical characteristics such as density, microhardness, tensile strength, flexural strength, and inter-laminar shear strength (ILSS) are analyzed of the tailored composites. Scanning electron micrographs (SEM) of tensile fractured specimens are also analyzed to identify the cause of failure. The experimental results reveal that the tensile, flexural, ILSS is increased up to 15 wt% filler loading and then decrease marginally; however the microhardness values increased with the increase in filler content. The density and voids are also affected by the variation of filler content in the composites.

Construction of micro-thermal conductive network of self-assembled CNTs hybrids with 1D–0D structure

In this context, carbon nanotubes (CNTs)/silver nanoparticles hybrids with special 1-dimensional–0-dimensional (1D–0D) structure were successfully fabricated via self-assemble of dopamine followed by reduction reactions of silver cations aiming to synthesize more efficient thermal conductive fillers for the formation of heat flow transfer network in PA6 matrix. FTIR, XRD, TG and TEM revealed the characteristics of functionalized CNTs. Meanwhile, the effect of CNTs hybrids with 1D–0D structure on the construction of heat flow network and thermal conductivity was also investigated. Experimental results showed that thermal conductivity of composites enhanced with increased filler content, the highest thermal conductivity of the PA6/CNTs hybrids composites reached 0.65 W m−1 K−1, which was 2.1 times that of pure PA6 and 32% higher than that of pristine CNTs-filled composites (0.55 W m−1 K−1) with same filler content (10 vol%), and this was ascribed to the better dispersion of fillers and enhanced interfacial interaction between fillers and matrix, as well as the special structure of CNTs hybrids that could abundance the heat transfer path. The crystallinities and dynamic thermal mechanical properties were also analyzed. The enhanced storage modulus (1940 MPa for pure PA6 to 3650 MPa for PA6/CNTs hybrids composites at 5 °C) and higher glass transition temperature along with the change of crystallization behavior of fabricated composites were in accordance with the thermal conductive behavior. The thermal conductive model and its mechanism were then proposed and further confirmed by scanning electron microscopy.

Novel Gradation Design of Porous Asphalt Concrete with Balanced Functional and Structural Performances

To improve the permeability of porous asphalt concrete (PAC) with a small nominal maximum aggregate size (NMAS) of 10 mm (PAC10), a novel gradation design by excluding the 0.075–3 mm aggregate was developed. This study aims to evaluate the functional and structural performances of the novel PAC10 with various mineral filler contents, using the conventional PAC10 and 13 mm NMAS PAC (PAC13) as reference, and develop the optimum gradation of the novel PAC10. The performance properties evaluated include moisture susceptibility, durability, high-temperature stability, low-temperature cracking resistance and permeability. The results indicated that for the two conventional PACs with the same fine aggregate and mineral filler content, PAC10 had worse permeability and rutting resistance, similar moisture susceptibility and durability, and better low-temperature cracking resistance, compared with the PAC13. The novel PAC10 showed better permeability than the conventional PAC10. With the increase of the mineral filler content, the structural performance of the novel PAC10 is improved, but its permeability is decreased. With a mineral filler content of 6%, the novel PAC10 can have balanced functional and structural performances, which are equivalent to those of the conventional PAC13.

Effects and mechanism of filler surface coating strategy on thermal conductivity of composites: A case study on epoxy/SiO2-coated BN composites

In order to make a systematic understanding of the effects and mechanism of the filler surface coating strategy on the thermal conductivity of composites, the silica coated BN was synthesized via Stöber sol-gel method and then incorporated into epoxy. The thermal conductivities of epoxy/BN@SiO2 composites were investigated experimentally, and it was found that increasing the coating thickness or filler content would decrease the enhanced effect of the strategy on thermal conduction. Fitting the thermal conductivities of composites with the EMA model indicates that the interfacial thermal resistance in the formed BN@SiO2 thermal conduction networks will increase with the increase of filler content, and then deteriorates the thermal conduction enhancement factor. Thus, the concept of the effective filler volume fraction was introduced in the strategy for the first time. Reducing the coating thickness will expand the effective filler volume fraction, but the upper limit of the effective filler volume fraction will not exceed the maximum random packing volume fraction of the fillers. The mechanism research provides an efficient guideline for further studying core-shell particles to improve the thermal conductivity of composites.

Influence of Concentration of Carbon and Glass Fibers, Melt Viscosity, and Number of Extrusions on the Porosity of Composites Based on Polyphenylene Sulphone, Polyethyrimide and Polyphenylene Sulfide

A comparative analysis of the effect on the porosity of composite filaments based on polyphenylene sulfone, polyetherimide and polyphenylene sulfide with discrete fibrous fillers, such factors as the filler concentration, melt viscosity and number of extrusion passes, was carried out. It is shown that with increasing filler content and decreasing melt viscosity, the porosity of composite filaments enhances. Upon repeated extrusion carbon-filled composites, a decrease in porosity is observed, however for glass-filled samples an increase in porosity is occurred. A comparative analysis showed that the filament samples based on polyetherimide have a higher porosity. The most resistant to pore formation are polyphenylene sulfone-based samples.