Fabrication of High Performance Fly Ash/Mica/Poly(ether-ether-ketone) Hybrid Composites

This paper deals with the preparation and characterization of poly(ether-ether-ketone) (PEEK) fly ash mica hybrid composites containing filler 5:15, 10:10 and 15:5 fly ash mica combinations loading. The performances and properties of the resulting 20 wt% loading of fly ash mica/PEEK hybrid composites were examined. The resulting hybrid composites of 20 wt% fly ash and mica with varying combinations exhibit the optimum improvement of mechanical properties and dielectric strength. MDSC showed the decrease in the crystallization temperature (Tc) with varying combinations of fly ash and mica. The morphology of fly ash/mica/PEEK hybrid composites was studied by SEM.     

聚氯乙烯/粉煤灰复合材料的制备与性能研究

制备了聚氯乙烯/粉煤灰复合材料,研究了粉煤灰的不同表面处理方式对共混物的力学性能和耐温性能的影响。结果表明:湿法处理粉煤灰的效果最好,不做处理的效果最差;粉煤灰会降低PVC材料的缺口冲击强度;添加5份处理过的粉煤灰可以提高PVC材料的拉伸强度;添加粉煤灰可以提高PVC材料的弯曲强度和弯曲模量,同时,耐温性也有一定的提高。     

Static and Dynamic Mechanical Properties of Vinylester Resin Matrix Composites Filled with Fly Ash

Summary: Vinylester resin matrix composites were prepared with a fly ash loading of 30, 40, 50 and 60 wt.‐%. Flexural properties of the composites were investigated. It was found that the flexural strength was lowered in all the filled composites, but the flexural modulus showed a significant increase of 10, 57, 112% in case of 30, 40 and 50 wt.‐% fly‐ash‐loaded composites respectively, compared to the neat resin. However, there was a decrease in the mechanical properties in case of 60 wt.‐% fly‐ash‐filled composites. The dynamic mechanical analysis was carried out to obtain information about the matrix‐filler interaction at the interface. The storage modulus value at room temperature was highest for the 50 wt.‐% fly‐ash‐filled composites, corroborating with the observed flexural modulus value. The fractured surfaces were examined under SEM and were correlated with the mechanical properties.

Large voids evident in the 60 wt.‐% fly‐ash‐filled composites.     

Recycled multilayer cartons as cellulose source in HDPE‐based composites: Compatibilization and structure‐properties relationships

In this article, an alternative mechanical recycling of multilayer carton scraps (MC), consisting in the use of MC without the physical separation of its different fractions (cellulose fibers and low‐density polyethylene, 80/20 wt/wt), is proposed. In particular, MC was considered as a source of cellulose fibers in the obtainment of high‐density polyethylene (HDPE)‐based composites. Composites containing up to 60 wt % of milled MC were prepared by reactive processing, i.e., by adding different amount (5 and 10 wt %) of a linear low‐density polyethylene grafted with maleic anhydride (coupling agent, maleated linear low‐density polyethylene) during HDPE/MC mixing. Then, structure/properties relationships were deeply investigated as a function of MC and coupling agent content. The coupling agent was able to induce a complete polymeric covering of cellulose fraction as well as a strong HDPE/cellulose interfacial adhesion. As a consequence, a significant improvement of mechanical properties at low and high deformation rates as well as a very interesting response of composites to water vapor permeability was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical Properties of Hemp‐Fibre‐Reinforced Euphorbia Composites

A composite material consisting of hydroxide‐modified hemp fibres and euphorbia resin was produced. The composites were tested in tension, short‐beam interlaminar shear stress and in impact. There was an increase in the tensile strength and modulus for resins with high‐hydroxyl‐group based composites. Similar results were obtained for interlaminar shear stress while low‐hydroxyl group euphorbia resin based composites exhibited high impact strength. The euphorbia resin with high hydroxyl content yielded composites with high stiffness. The use of euphorbia‐based resins in composite manufacture increases the value of the euphorbia oil as well as creating a new route of composite manufacturing.

     

High-Temperature Resistant Composites in the AlN–SiC–MoSi2 System

Two fully dense composites containing AlN, SiC, and MoSi₂ in different amounts were produced by hot pressing. Young modulus, hardness, electrical conductivity, and thermal expansion coefficient were measured at room temperature. Strength and toughness were evaluated up to 1300°C in air. According to statistical analysis, the temperature has little or no effect on high-temperature fracture behavior of the composites. These electroconductive materials are suitable for thermomechanical applications at high temperature, the strength being about 600 MPa at 1300°C.     

Evaluation of Coupling Agents in Poly(propylene)/Fly Ash Composites: Effect on Processing and Mechanical Properties

Composites containing 50 wt.‐% fly ash in a PP homopolymer were prepared via batch mixing and compression moulding. The following coupling agents were evaluated: Lubrizol Solplus C800, N,N′‐(1,3‐phenylene)dimaleimide, γ‐methacryloxypropyltrimethoxysilane and maleic‐anhydride‐grafted PP. At the filler level investigated, C800 gave the best balance of composite strength and toughness. In the latter case filler‐matrix adhesion appeared weaker relative to γ‐MPS, BMI and m‐PP, all of which gave excessively strong filler‐matrix adhesion leading to a reduction in composite toughness. The unexpected weakness of the C800/fly ash interaction may be related to removal of surface calcium ions from the fly ash via reaction of a single calcium ion with two C800 molecules.

     

Synthesis of EP‐POSS mixture and the properties of EP‐POSS/epoxy,SiO2/epoxy,and SiO2/EP‐POSS/epoxy nanocomposite

The hybrid material of EP‐POSS mixture was synthesized by the hydrolysis and condensation of (γ‐glycidoxypropyl) trimethoxysilane. A series of binary systems of EP‐POSS/epoxy blends, epoxy resin modified by silica nanoparticles (SiO₂/epoxy), and ternary system of SiO₂/EP‐POSS/epoxy nanocomposite were prepared. The dispersion of SiO₂ in the matrices was evidenced by transmission electron micrograph, and the mechanical properties, that is, flexural strength, flexural modulus, and impact strength were examined for EP‐POSS/epoxy blends, SiO₂/epoxy, and SiO₂/EP‐POSS/epoxy, respectively. The fractured surface of the impact samples was observed by scanning electron micrograph. Thermogravimetry analysis were applied to investigate the different thermal stabilities of the binary system and ternary system by introducing EP‐POSS and SiO₂ to epoxy resin. The results showed that the impact strength, flexural strength, and modulus of the SiO₂/EP‐POSS/epoxy system increased around by 57.9, 14.1, and 44.0% compared with the pure epoxy resin, T_i, T_max and the residues of the ternary system were 387°C, 426°C, and 25.2%, increased remarkably by 20°C, 11°C and 101.6% in contrast to the pure epoxy resin, which was also higher than the binary systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 810‐819, 2013     

Enhancement of the mechanical properties and interfacial interaction of a novel chitin‐fiber‐reinforced poly(ϵ‐caprolactone) composite by irradiation treatment

The effects of the fiber reinforcement of a novel bioabsorbable chitin‐fiber‐reinforced poly(?‐caprolactone) (PCL) composite were improved by irradiation treatment. The tensile strength and tensile modulus of the treated specimens were enhanced with respect to those of the untreated specimens. An increase in the fiber content (C_f) resulted in an increase in this enhancement tendency until C_f was 45%. A further increase in C_f increased the tensile modulus but decreased the strength. The flexural strength and flexural modulus were increased for the irradiation‐treated specimens in the same way as the tensile test. The microstructure of the tensile fracture showed an improvement in interfacial bonding for the irradiated specimens. The glass‐transition temperature (T_g) of the composite increased with an increase in C_f for the irradiation‐treated specimens, but there was no change in T_g for the untreated specimens with various values of C_f. This indicated that, for the composites with irradiation treatment, the fiber intensively affected the molecular segmental motion of PCL and thereby enhanced the interfacial interaction between the matrices and fibers. The same slope of the storage modulus (G′) versus the loss modulus (G″) for the irradiated specimens suggested an increase in the compatibility of the composite in comparison with the decrease in the slope with increasing C_f for the untreated specimens. All this demonstrated that there was some interfacial reaction between the fiber and matrix that resulted in the presence of an interfacial phase and improved the mechanical properties of the materials. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 486–492, 2002; DOI 10.1002/app.10149     

Synthesis and Characterization of Novel Polyurethane Composites Based on Hybrid Inorganic/Organic Phosphazene‐Containing Microspheres

Novel polyurethane (PU) composites were prepared, based on hybrid inorganic/organic phosphazene‐containing microspheres. The FT‐IR spectra have shown that the microspheres have been linked with PU matrix. The microstructure of the composites is investigated by SEM. In comparison with PU, the glass transition temperatures and thermal stability of the composites are increased. The results from tensile testing of the composites have indicated that tensile strength is improved and elongation at break is almost invariable. The investigation on the surface properties of the composites showed that the water contact angles are obviously increased by adding 2 and 4 wt.‐% microspheres to the matrix.

     

Investigation of mechanical properties of alumina nanoparticle‐loaded hybrid glass/carbon‐fiber‐reinforced epoxy composites

This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1–5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1–5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39749.     

Preparation and properties of melt‐blended polylactic acid/polyethylene glycol‐modified silica nanocomposites

One commercial type of fumed silica modified with methoxy polyethylene glycol (mPEG) plasticizer was incorporated into polylactic acid (PLA) biobased polymer to improve its performance. The modification on silica was confirmed through Fourier transform infrared spectra, nuclear magnetic resonance, and TGA assessments. The grafting percentage of mPEG onto silica was about 19.8 wt %. Transmission electron microscope revealed a similar degree of dispersion for control silica and modified silica‐filled PLA nanocomposites. Not much difference in the glass transition temperatures at various silica contents was found for PLA/control silica systems from the differential scanning calorimetry measurement, but the glass transition temperature of PLA/modified silica nanocomposite at 10 phr of modified silica showed up to 11°C decrement. It was suggested that the mPEG plasticizer efficiently plasticized the PLA matrix through the enhanced segmental mobility of PLA chains. Young's modulus of PLA was about 2133 ± 53 MPa, and the value for the nanocomposite increased to 2547 ± 54 MPa at 10 of phr control silica mainly due to the reinforcing effect from nanoparticles. For modified silica, Young's modulus decreased at various silica contents. The elongation at break for modified silica‐filled cases was higher than that of control silica‐filled cases. These results were attributed to the plasticizing effect of surface modifier. Optical transmittance for pristine PLA was generally in a similar order as PLA/control silica and modified silica cases at various silica contents. The results agreed with the morphology observation as well. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Irradiation dose control for polymer‐matrix composites fabricated by in situ curing with low‐energy electron beam

The electron beam (EB) with emitting energies lower than 150 keV is applicable in in situ curing of polymer‐matrix composites; however, being poor in penetration ability, it leads to significant attenuation of irradiation dose along the prepreg thickness. In this study, polymer‐matrix composites were fabricated by low‐energy EB irradiation curing, and the effect of dose control of double‐sided irradiation was systematically investigated. Experimental results showed that laminates fabricated by single‐sided irradiated prepregs were low in interlaminar shear strength (ILSS) owing to incomplete curing after being post cured at 180 °C for 30 min. A double‐sided irradiation method which included irradiation of equal dose and different doses on both sides of the prepreg was proposed to overcome this difficulty. Analysis showed that under a total dose of 70 and 100 kGy, the ILSS results were high owing to the low curing degree of two adhesive surfaces; under a total dose of 130 and 160 kGy, laminates fabricated with different EB irradiation doses on both sides exhibited enhanced ILSS compared to those with equal dose on both sides, owing to physical adhesion and chemical crosslinking between layers. The ILSS results exhibited the largest increase of 18.9 and 60.5%, respectively, by tuning the dose differences between both sides of the prepregs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44944.     

Fabrication and Characterization of Soluble Multi‐Walled Carbon Nanotubes Reinforced P(MMA‐co‐EMA) Composites

Summary: Soluble multi‐walled carbon nanotubes (s‐MWNTs), obtained via amidation reaction of octadecylamine with purified multi‐walled carbon nanotubes (p‐MWNTs), were solution‐mixed with P(MMA‐co‐EMA) at various loadings. Compared to the p‐MWNTs/P(MMA‐co‐EMA) composites, the s‐MWNTs/P(MMA‐co‐EMA) composites showed great improvement both in Young's modulus and tensile strength. With the addition of 10 wt.‐% s‐MWNTs, the Young's modulus and tensile strength of s‐MWNTs/P(MMA‐co‐EMA) composite have 135% and 49% increase over the pure P(MMA‐co‐EMA), respectively, and a 9.2% increase in Young's modulus and 12.8% increase in tensile strength over that of 10 wt.‐% p‐MWNTs composite. With the increase of MWNTs content, the T_g increases from 89 to 106 °C. SEM studies show that the s‐MWNTs are well dispersed in the polymer matrix. Good dispersion of s‐MWNTs in polymer matrix and great interfacial bonding between s‐MWNTs and P(MMA‐co‐EMA) may be the key reason for the improvement of the mechanical properties.

Stress‐strain curves of the MWNTs and P(MMA‐co‐EMA) composites.     

Tensile and Impact Properties of Hollow Glass Bead‐Filled PVC Composites

The tensile and notched Izod impact properties of poly(vinyl chloride) (PVC) composites filled with hollow glass beads (HGB) were measured at room temperature by means of an Instron materials testing machine to investigate the effects of the filler content and size on these mechanical properties. The results showed that the tensile yield strength (σ_yc) decreased gently with increasing HGB volume fraction (ϕ _f), while the tensile break strength (σ_bc) of the composites was somewhat greater than that of the unfilled PVC within ϕ _f = 0–20%. In addition, the dependence of σ_bc on ϕ _f was not obvious. The effect of HGB size on both σ_yc and σ_bc was insignificant. When ϕ _f < 5%, the notched impact strength (σ_IC) of the composites decreased quickly with increasing ϕ _f, and then it decreased slightly with the increase of ϕ _f. Similarly, the influence of the filler size on the impact properties was insignificant. Furthermore, the σ_yc of the samples was estimated using a tensile equation proposed in a previous paper. A good agreement was shown between the calculations and the measured data.     

Benzoylgermanium Derivatives as Novel Visible‐Light Photoinitiators for Dental Composites

New dibenzoylgermanium derivatives are synthesized starting from various dithioacetal protected benzaldehydes by a coupling reaction with different dialkyldichlorogermanes and subsequent oxidative cleavage of the protecting group. The synthesized germanium compounds show a significantly stronger blue light absorption than camphorquinone. During irradiation, the dibenzoylgermanium derivatives undergo photodecomposition under formation of radicals. Therefore, the different dibenzoylgermanium derivatives are used as amine‐free visible‐light photoinitiators for dental cements and composites. Composites based on the different dibenzoylgermanes are storage‐stable and show a significantly improved bleaching behavior over composites with CQ/amine photoinitiators.

     

High-Temperature Mechanical Properties of SiC–Mo5(Si,Al)3C Composites

SiC–Mo₅(Si,Al)₃C composites were fabricated by the melt infiltration process, and the infiltration characteristics were studied in detail. Fracture strength and toughness were measured up to 1600°C using a three-point bending test and indentation strength method, respectively. Both fracture strength and toughness significantly increased at 1400°C with respect to the values at room temperature. These increases were mainly attributed to plastic deformation of the infiltrated Mo₅(Si,Al)₃C phases at elevated temperatures, which acted as ductile toughening inclusions. Compressive creep tests were used to study the creep behavior of the composite in the range of 1550°–1650°C and 150–200 MPa. The stress exponent and activation energy were 1.3 and 277 kJ/mol, respectively. Preliminary oxidation tests showed that the composites exhibited good oxidation resistance at 1500°C because of the formation of a dense oxide scale.     

From PET Nanofibrils to Nanofibrillar Single‐Polymer Composites

The preparation of nanofibrillar composite (NFC) materials using single‐polymer nanofibrils as starting materials is described. Such a possibility is offered by (i) the concept of polymer/polymer NFCs, which have recently been manufactured and represent a further development in the field of microfibril‐reinforced composites, and (ii) the opportunity to isolate neat nanofibrils through selective dissolving of the second blend component. The resulting nanofibrillar single‐polymer composites are characterized by superior mechanical properties (the tensile modulus and strength are improved up to 350%), competing with glass‐fiber‐reinforced PET.

     

Effects of filler–filler and polymer–filler interactions on rheological and mechanical properties of HDPE–wood composites

High‐density polyethylene (HDPE)–wood composite samples were prepared using a twin‐screw extruder. Improved filler–filler interaction was achieved by increasing the wood content, whereas improved polymer–filler interaction was obtained by adding the compatibilizer and increasing the melt index of HDPE, respectively. Then, effects of filler–filler and polymer–filler interactions on dynamic rheological and mechanical properties of the composites were investigated. The results demonstrated that enhanced filler–filler interaction induced the agglomeration of wood particles, which increased the storage modulus and complex viscosity of composites and decreased their tensile strength, elongation at break, and notched impact strength because of the stress concentration. Stronger polymer–filler interaction resulted in higher storage modulus and complex viscosity and increased the tensile and impact strengths due to good stress transfer. The main reasons for the results were analyzed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Toughening effects of interleaved nylon veils on glass fabric/low‐styrene‐emission unsaturated polyester resin composites

The effectiveness of using interleaved nylon veils to increase the interlaminar toughness of glass fiber reinforced, low‐styrene emission unsaturated polyester resin composites has been investigated. Samples were manufactured by a hand lay‐up technique followed by compression moulding. Nylon 66 veils were used, with the veil content varying from 0% to 4% by weight. Double cantilever beam, short beam shear, and three point bend tests were performed. The increasing levels of nylon veil content improved the interlaminar toughness of the composites, which was characterized by critical strain energy release rate (G_IC). The maximum G_IC for crack propagation of a nylon interleaved composite increased by almost 170% over the baseline glass fiber reinforced composite. Dynamic Mechanical Analysis revealed an increase in the damping parameter of up to 117%. Image analysis via Digital Image Correlation and Scanning Electron Microscopy revealed increased fiber bridging between adjacent plies as a key reason for these improvements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41462.