Recycling studies of marble processing waste: Composites based on commercial epoxy resin

Marble waste was obtained from marble processing plant wastewater with precipitation using different coagulants, such as sepiolite, zeolite, and pumice in dosages of 0.5–8 g/500 mL and mixed in 20 wt % with commercial epoxy resin. The effects of marble, coagulant type and dosage on the physicomechanical and thermal properties were investigated. The incorporation of marble processing waste particles increases the 10% decomposition temperature of pure epoxy by 5–50°C. Surface hardness, tensile strength, percentage elongation, and stress at maximum load of the composites were higher than those of pure resin, too. The composites reinforced with marble processing waste-pumice showed about 10% increase in elastic modulus, whereas the composite reinforced with marble processing waste-sepiolite or zeolite showed about 76.67–143.33% increase in elastic modulus over the pure epoxy matrix. Scanning electron microscopy (SEM) was used for characterization of surface and cross sections of the composites to verify the results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Utilization of flyash as filler for polybutyleneterepthalate‐toughened epoxy resin

Flyash, a waste product generated in large quantities in thermal power plants, has been posing problems of disposal. The purpose of the present work was to make a meaningful utilization of flyash as filler in neat epoxy resin matrix and 2% Polybutyleneterepthalate (PBT)/epoxy blend matrix. For this purpose, the tensile, flexural, compression, impact, chemical resistance, and water absorption properties were studied. Composites were made with varying proportion of flyash in epoxy resin and 2% PBT/epoxy blend matrix. Tensile, flexural, and compression properties were measured on a computerized universal testing machine, according to ASTM procedures. Impact strength was determined using izod impact tester for un‐notched specimens. PBT (2%)/epoxy blend matrix composites showed improved mechanical properties over neat epoxy flyash composites. All the composites were found to have good chemical resistance toward acids, solvents, and alkalies. These composites showed better water resistance over neat epoxy flyash composites. POLYM. ENG. SCI. 46:946–953, 2006. © 2006 Society of Plastics Engineers     

Mechanical and thermal properties of a novel composite prepared with epoxy resin and lateritic ore

Composites made from epoxy resins (ERs) are one of the important polymer groups used in different industries due to their good mechanical and thermal properties. Many attempts have been done to improve both the mechanical and the thermal properties of ER composites and to lower the cost of ER composites with addition of inexpensive fillers such as calcium carbonate, kaolin clays, silica, talc, etc. In this study novel lateritic ore (LO) filler was used in diglycidyl ether of bisphenol A‐type ER. Different addition percentages (5–20%) of both natural LO (nLO) and modified LO (mLO) into ER were tested to determine the influence on mechanical and thermal properties of newly produced composites. Surface hardness, Young's modulus, tensile strength, elongation at break, water sorption, adhesion, and thermal stability of composites were determined and were compared with pure ER. Results showed that the addition of nLO/mLO has positive effect on mechanical and thermal properties. Morphological characterization by scanning electron microscopy and structural characterization by X‐ray diffraction revealed that addition nLO/mLO distributed homogenously throughout the composites. POLYM. COMPOS. 34:1375–1381, 2013. © 2013 Society of Plastics Engineers     

Synthesis and application of thermal latent initiators of epoxy resins: A review

Epoxy resin, which is extensively used in civil and industrial applications, shows excellent comprehensive performance, especially as a polymer matrix used in fiber-reinforced composites. A thermal latent initiator, used as an epoxy curing agent, has high storage stability and is widely applied in the preparation of epoxy-based blends and fiber-reinforced composites. In this review, the basic properties of epoxy resins and commonly used curing agents are discussed while progress on the synthesis of thermal latent initiators is reviewed in detail. Moreover, the curing mechanisms, thermal stability, and mechanical properties of epoxy resins with thermal latent initiators are also discussed.     

Pseudoreinforcement effect of multiwalled carbon nanotubes in epoxy matrix composites

The carbon nanotube possesses outstanding physical properties. Theoretically, adding carbon nanotubes into a polymer matrix can remarkably improve the mechanical properties of the polymer matrix. In the present work, a series of composites was prepared by incorporating multiwalled carbon nanotubes (MWNTs) into an epoxy resin. The influences of MWNT content and curing temperature on the flexural properties of the epoxy resin were investigated. The results showed that a very low MWNT content should be used to ensure homogeneous dispersion of MWNTs in the epoxy matrix. A higher MWNT content may lead to deteriorated mechanical properties of the composites because of the aggregation of MWNTs. A decline in the flexural properties of the neat epoxy resin with increasing curing temperature was found. However, under the same curing conditions, improvement in flexural properties was observed for the composite with the low MWNT content and a mild curing temperature. The improvement was far beyond the predictions of the traditional short‐fiber composite theory. In fact, this improvement should be attributed to the retarding effect of MWNTs on the curing reaction of epoxy matrix. Therefore, the improvement in the flexural properties was only a pseudoreinforcement effect, not a nano‐reinforcement effect of the MWNTs on the epoxy resin. Perhaps, it is better for MWNTs to be used as functional fillers, such as electrical or thermal conductive fillers, than as reinforcements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3664–3672, 2006     

Physico‐mechanical,thermal, and coating properties of composite materials prepared with epoxy resin/steel slag

The interest in using different solid waste as reinforcement in polymer composite preparation has increased considerably in recent years. Slag is one of the inorganic waste materials obtained from ore processing. In this work, epoxy composites filled with different percentages of slag were prepared. Physico‐mechanical, thermal, and coating properties of these composites were determined depending on the amount of filler, type of hardener, and polyethylene glycol (PEG) addition. X‐ray diffraction (XRD) studies were carried out to examine the compatibility of the filler and epoxy resin and XRD results showed good compatibility between two materials. The results of mechanical testing illustrated that hardness of the epoxy composites containing anhydride was partially higher than with Epamine PC17 in contrast to elongation at break. The tensile strength and Young modulus decreased with increasing filler amount. When compared to neat epoxy resin, corrosion, and adhesion properties of the composites with filler addition did not change significantly. The highest water sorption values were obtained for the epoxy composites with PEG addition. The composites hardened by anhydride had better thermal stability than the composites including Epamine PC17. POLYM. COMPOS., 38:1974–1981, 2017. © 2015 Society of Plastics Engineers     

Nanoclay and long-fiber-reinforced composites based on epoxy and phenolic resins

In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal conductivity and structure of non-covalent functionalized graphene/epoxy composites

Non-covalent functionalization was used to functionalize graphene nanosheets (GNSs) through π–π stacking of pyrene molecules with a functional segmented polymer chain, which results in a remarkable improvement in the thermal conductivity of GNS-filled polymer composites. The functional segmented poly(glycidyl methacrylate) containing localized pyrene groups (Py-PGMA) was prepared by atom transfer radical polymerization, and Py-PGMA was characterized by nuclear magnetic resonance spectroscopy. Raman spectra, X-ray photoelectron spectroscopy and thermogravimetric analysis reveal the characteristics of Py-PGMA–GNS. Differential scanning calorimetry indicated that the functional groups on Py-PGMA–GNSs can generate covalent bonds with the epoxy matrix, and further form a cross-linked structure in Py-PGMA–GNS/epoxy composites. The Py-PGMA on the GNS surface not only plays an important role to facilitate a homogeneous dispersion in the polymer matrix but also improves the GNS–polymer interaction, which results in a high contact area. Consequently, the thermal conductivity of integrated Py-PGMA–GNS/epoxy composites exhibited a remarkable improvement and is much higher than epoxy reinforced by multi-walled carbon nanotubes or GNSs. The thermal conductivity of 4 phr Py-PGMA–GNS/epoxy has about 20% (higher than that of pristine GNS/epoxy) and 267% (higher than pristine MWCNT/epoxy).     

Preparation and characterization of liquid crystalline polyurethane‐imide modified epoxy resin composites

Liquid crystalline polyurethane‐imide (PUI) was synthesized from polyethyleneglycol, toluene diisocyarate, and pyromellitic dianhydride by solution polymerization and characterized by FTIR spectrum. The liquid crystal properties of PUI were verified by differential scanning calorimetry, polarizing microscope (POM), and X‐ray diffraction. PUI is a longitudinal liquid crystal with LC sequences in the backbone along the main‐chain direction. PUI was used to blend with epoxy resin(ER) as a modifier. The mechanical properties, thermal property, and morphology of PUI/ER composites were investigated. It was found that PUI was a kind of thermotropic liquid crystal material within a wide range of temperature. Remarkable improvement in strength and toughness of ER/PUI composites was achieved by the blending of PUI with epoxy in appropriate proportions. The maximum for bending strain and bending strength of the composite reached the level of 10.65% and 178 MPa, respectively when the mass fraction of PUI was 15 wt%. The mechanical behaviors of the PUI/ER were consistent with morphology analysis of the fracture surfaces of PUI/ER composites from SEM. POLYM. ENG. SCI., 54:1704–1711, 2014. © 2013 Society of Plastics Engineers     

Effects of nanotube modification on the dielectric behaviors and mechanical properties of multiwall carbon nanotubes/epoxy composites

Multiwall carbon nanotubes (MWNTs) were modified by three methods, namely, oxidizing the tubes and opening both ends, filling the tubes with Ag, and grafting the tubes with hexamethylene diamine. Modified MWNTs/epoxy composites were prepared by melt‐mixing epoxy resin with the tubes. Transmission electron microscope images showed that the modified MWNTs can be dispersed in the epoxy matrix homogeneously. The dielectric behaviors and mechanical properties of the composites were investigated. The dielectric and mechanical properties of the modified MWNTs/epoxy composites were considerably improved compared with those of the epoxy matrix. The tensile strengths of the Ag‐filled, opened, and grafted MWNTs composites at the same filler content of 1.1 wt% were higher by ～30.5%, 35.6%, and 27.4%, respectively, than that of neat epoxy. The Izod notched impact strength of the grafted MWNTs/epoxy composite with filler content of 1.1 wt% was approximately four times higher than that of neat epoxy. A dielectric constant of ～150 of the composite with 1.1 wt% Ag‐filled nanotubes was observed in the low‐frequency range, which was ～40 times higher than that of the epoxy matrix. The proper modification of nanotubes provides a way to improve the properties of the polymer‐based composites. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Ultrasonic properties of epoxy resin/marble waste powder composites

Non‐destructive techniques are suitable alternatives for characterization of composites. The aim of this study is to analyze the composites of epoxy resin (ER)/marble waste powder (MWP) by ultrasonic method. The effects of marble powder, coagulant type, and dosage on the ultrasonic properties of ER/MWP composites were investigated. The ultrasonic wave velocities of composites were measured with the pulse–echo method at room temperature by a flaw detector. The values of the acoustic impedance, Poisson's ratio, and elastic constants of the samples were calculated by the measured values of the densities and both longitudinal and shear ultrasonic wave velocities. According to the results, the ER/MWP composite using sepiolite coagulant in dosages of 4 g/500 mL has showed the highest values of elastic constants. POLYM. COMPOS. 36:584–590, 2015. © 2014 Society of Plastics Engineers     

Enhanced mechanical properties of epoxy composites using cellulose micro- and nano-crystals

Epoxy polymers are commonly utilized in structural applications due to their high bearing capacity and excellent chemical resistance. However, their inherent brittleness poses a significant challenge for their use in high shock and fracture strength products. To address this shortcoming, fillers can be incorporated into the polymer during preparation. In this study, we aimed to investigate the effect of incorporating cellulose-based fillers, namely cellulose nanocrystals (CNCs) and microcrystalline cellulose (MCC), on the mechanical properties of epoxy polymer composites. The study evaluated the impact of various factors, including filler concentration, particle size, and moisture content, on the mechanical properties of the composites. The results demonstrated that the incorporation of CNC or MCC powders at concentrations below 5% could enhance the mechanical properties of the resulting epoxy composites without adversely affecting their surface and thermal properties. The maximum tensile strength and fracture toughness of the filler-based epoxy composites were achieved at 2 and 4 wt% for CNCs and MCC, respectively. CNCs with a smaller particle size distribution were found to be much more effective than MCC in improving the mechanical properties of the epoxy composites. Furthermore, utilizing dried fillers resulted in a higher improvement in tensile strength, which was achieved at lower filler concentrations.     

Mechanical and thermal properties of biphenyldiol formaldehyde resin/gallic acid epoxy composites enhanced by graphene oxide

In this study, the gallic acid‐based epoxy resin (GA‐ER) and alkali‐catalysed biphenyl‐4,4′‐diol formaldehyde resin (BPFR) are synthesized. Glass fibre‐reinforced GA‐ER/BPFR composites are prepared. Graphene oxide (GO) is used to improve the mechanical and thermal properties of GA‐ER/BPFR composites. Dynamic mechanical properties and thermal, mechanical, and electrical properties of the composites with different GO content are characterized. The results demonstrate that GO can enhance the mechanical and thermal properties of the composites. The glass transition temperature, T_g, of the BPFR/GA‐ER/GO composites is 20.7°C higher than the pure resin system, and the 5% weight loss temperature, T_d5, is enhanced approximately 56.6°C. When the BPFR: GA‐ER mass ratio is at 4 : 6 and GO content is 1.0–1.2 wt %, the tensile and impact strengths of composites are 60.97 MPa and 32.08 kJ/m² higher than the pure resin composites, respectively. BPFR/GA‐ER composites have better mechanical properties, and can replace common BPA epoxy resins in the fabrication of composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42637.     

Effect of organosilane coupling agents on microstructure and properties of nanosilica/epoxy composites

Three types of silane coupling agents, γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane, were used as modifiers to modify the surface of the nanosilica, respectively, and the nanocomposites of the epoxy resin filled with nano‐sized silica modified by three silane coupling agents were prepared by physical blending. The properties of the modified silica nanoparticles were characterized by Fourier transform infrared spectrum and particle‐size analyzer. The microstructure, mechanical behavior, and heat resistant properties of the nanocomposites were investigated by transmission electron microscopy, scanning electron microscopy, thermo gravimetric analyses, differential thermal gravity, differential scanning calorimetry, and flexural tests. The results showed that these modifiers are combined to the surfaces of nanosilica by the covalent bonds, and they change the surface properties of nanosilica. The different structures of coupling agents have different effects on the dispersibility and stability of modified particles in the epoxy matrix. In comparison, the silica nanoparticles modified by γ‐glycidoxypropyltrimethoxysilane exhibit a good dispersivity. The nanocomposites with 4 wt% weight fraction nanosilica modified by γ‐glycidoxypropyltrimethoxysilane have higher thermal decomposing temperature and glass transition temperature than those of the other two composites with the same nanosilica contents, and they are raised by 43.8 and 8°C relative to the unmodified composites, respectively. The modified silica nanoparticles have good reinforcing and toughening effect on the epoxy matrix. The ultimate flexural strengths of the composites with 4 wt% nanoparticles modified by γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane are increased by 10, 30, and 8% relative to the unmodified composites, respectively. The flexural fracture surfaces of modified composites present ductile fracture features. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

Thermal and mechanical properties of epoxy composites reinforced by a natural hydrophobic sand

If a low weight percentage of crude fine fillers can improve properties of polymer materials directly without complicated chemical treatment process involved, it will be significant for many industrial applications. Our previous study indicated that a kind of Cancun natural sand could be an effective filler material for polymer composites. In this current work, the epoxy composites reinforced by this kind of natural sand particles were prepared and thermal and mechanical properties of the composites containing up to 5 wt % of the sand particles were characterized. Results showed that the highest flexural strength appears in the epoxy composite containing 1 wt % sand particles. A damage model was used to interpret the flexural properties, which showed an acceptable agreement with the experimental results. The glass transition temperature, high temperature storage modulus, and dimensional stability of the sand/epoxy composites monotonically increased with the addition of the sand particles. The sand particle/epoxy composites also displayed a noticeable enhancement in thermal conductivity. Theoretical analysis showed that in addition to conduction, other heat transport mechanisms played roles in the improved heat transmission through the composites. As a natural porous micron-scale material, Cancun sand has the potential for applications in cost-effective composites with enhanced mechanical and thermal properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fabrication of thermally conductive composite with surface modified boron nitride by epoxy wetting method

Boron nitride (BN) particles fabricated with different surface treatments were used to prepare thermally conductive polymer composites by epoxy wetting. The polar functionality present on the BN particles allowed the permeation of the epoxy resin because of a secondary interaction, which allowed the fabrication of a composite containing high filler concentration. The different cohesive energy densities of the synthesized material due to a functional-group-induced surface treatment effect on surface free energy and wettability determined the thermal and mechanical properties of the polymer. The results indicate that surface-curing agents interrupt the interaction between the filler and matrix, and do not always enhance thermal conductivity. Moreover, the composites showed maximum thermal conductivity at 30 wt% epoxy loading when the fixed-pore volume fraction reached in the filtrated BN film. The measured storage modulus was also enhanced by surface treatment because of the sufficient interface produced and interaction between the large amount of the filler and epoxy.     

Synergetic effects of graphene platelets and carbon nanotubes on the mechanical and thermal properties of epoxy composites

A remarkable synergetic effect between the multi-graphene platelets (MGPs) and multi-walled carbon nanotubes (MWCNTs) in improving the mechanical properties and thermal conductivity of epoxy composites is demonstrated. Stacking of individual two-dimensional MGPs is effectively inhibited by introducing one-dimensional MWCNTs. Long and tortuous MWCNTs can bridge adjacent MGPs and inhibit their aggregation, resulting in a high contact area between the MGP/MWCNT structures and the polymer matrix. Scanning electron microscope images of the fracture surfaces of the epoxy matrix showed that MWCNT/MGP hybrid nanofillers exhibited higher solubility and better compatibility than individual MWCNTs and MGPs did. The tensile strength of GD400-MWCNT/MGP/epoxy composites was 35.4% higher than that of the epoxy alone, compared to only a 0.9% increase in tensile strength for MGP/epoxy composites over the epoxy compound. Thermal conductivity increased by 146.9% using GD400-MWCNT/MGP hybrid fillers and 23.9% for MGP fillers, compared to non-derivatised epoxy.     

The influence of structural order of anthracite fillers on the curing behavior,morphology, and dynamic mechanical thermal properties of epoxy composites

This article concerns the study of polymer composites with anthracite fillers of various structural order. Raw Svierdlovski anthracite of turbostratic structure and the anthracite thermally treated at 2,000°C of graphite‐like structure were used as fillers of low‐molecular‐weight diglycidyl ether of bisphenol A cross‐linked with aliphatic amine. Two anthracites of extremely different structures were compared to natural graphite that is composed of well‐ordered graphene sheets. Systematic studies of the influence of the structure of anthracite filler on the curing behavior, morphology, dynamic mechanical thermal properties, and thermal stability of epoxy composite were performed. It was found that the structure of anthracite filler affects the cross‐linking reactions of the epoxy matrix as well as the morphology of the composites and their viscoelastic properties. Raw anthracite added to epoxy matrix had a visible effect on the activation energy and differential scanning calorimeter parameters of the curing process, in contrast to the epoxy matrix modified with anthracite heated at 2,000°C. On the contrary, the effect of anthracite on dynamic mechanical behavior of composites is more evident when the anthracite prepared at 2,000°C was used as a filler. POLYM. COMPOS., 36:336–347, 2015. © 2014 Society of Plastics Engineers     

High-performance composite from epoxy and glass fibers: Morphology,mechanical, dynamic mechanical,and thermal analysis

Diglycidyl ether of bisphenol-A type epoxy resin cured with diamino diphenyl sulfone was used as the matrix for fiber-reinforced composites to get improved mechanical and thermal properties for the resulting composites. E-glass fiber was used for fiber reinforcement. The morphology, tensile, flexural, impact, dynamic mechanical, and thermal properties of the composites were analyzed. The tensile, flexural, and impact properties showed dramatic improvement with the addition of glass fibers. Dynamic mechanical analysis was performed to obtain the T_g of the cured matrix as well as the composites. The improved thermal stability of the composites was clear from the thermogravimetric analysis. Scanning electron micrographs were taken to understand the interfacial adhesion between the fiber and the matrix. The values of mechanical properties were compared with modified epoxy resin composite system. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

The mechanisms and mechanics of the toughening of epoxy polymers modified with fullerene C60

This study examined the effect of fullerene C₆₀ on the mechanical properties of epoxy‐based polymer nanocomposites with different C₆₀ loadings. Mechanical testing shows that compared with neat epoxy, mechanical and toughening properties of composites are greatly improved. Young's modulus increased 6–20% by inducing 0.01–0.12 wt% of fullerene into the matrix resin. Furthermore, the toughness of the composite was improved up to about 200%. The toughening mechanism has been discussed. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers