Elastic and plastic properties of epoxy resin syntactic foams filled with hollow glass microspheres and glass fibers

Representative volume elements of syntactic foams with a random filling of short glass fibers and hollow glass microspheres in epoxy resin were established by a random sequential adsorption method. The fiber volume fraction was set at 4%, and the microsphere volume fraction range was from 5 to 30%. This numerical simulation was studied with ANSYS software. The influence on the elastic and plastic mechanical properties of syntactic foams of the microsphere volume fraction and relative wall thickness were investigated, and the plastic strain evolution process in the composites was analyzed. The results show that the compressive yield limit and Young's modulus values of the syntactic foams decreased with increasing microsphere volume fraction when the microsphere relative wall thickness was 0.02, but these properties were enhanced with increasing microsphere volume fraction when the relative wall thickness exceeded 0.04. The specific strength and tangent modulus values of the composites increased with increasing microsphere volume fraction. In addition, we observed that the yield stress, Young's modulus, and tangent modulus values of the syntactic foams were obviously enhanced by the addition of glass fibers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44188.     

Impact performance of laminates made of syntactic foam and glass fiber reinforced epoxy as protective materials

Impact performance of two‐dimensional quasi‐isotropic laminates subjected to impact loading with flat‐ended impactors has been studied in terms of impact stress, strain rate, and volume fraction of laminae. A simple model was formulated to predict impact stress within an elastic limit as a function of volume fractions of laminae. Individual impact parameters for syntactic foam and fiber‐reinforced epoxy were experimentally obtained at impact energy levels of 0.54 and 0.87 Joule, and used to predict impact stress of the laminates made of the same materials. A reasonable agreement between predictions and experimental results were found. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2306–2310, 2003     

On the compressive elasticity of epoxy resins filled with hollow glass microspheres

The mechanical properties of a hollow glass microsphere-filled epoxy resin composite system were investigated in air as a function of the weight content of particles ranging from 0 to 15.38% (wt/wt). The analysis based on necessarily modified classical models together with structural observations enabled explanation of the composition dependencies of elastic moduli of the blends studied. It was found that, together with a presumption of no interfacial adhesion between the filler and matrix, an interlayer of immobilized matrix with changed mechanical properties compared to the formal matrix seems to strongly affect the mechanical behavior of the composite. © 1996 John Wiley & Sons, Inc.     

Processing and characterization of syntactic carbon foams containing hollow carbon microspheres

The effects of heat-treatment on the properties of carbon foams were studied. The carbon foam was first prepared by adding hollow carbon microspheres to phenolic resin, followed by post-curing, pre-carbonization and carbonization. The mechanisms of failure behaviour and the increase of electrical and thermal conductivities showed that the properties of the foams were influenced by the heat-treatment temperature. Results showed that the introduction of more interval voids during carbonization resulting in a reduction of the mechanical properties. Carbon foams with electrical conductivity of 1.20 S/cm and thermal conductivity of 12.85 W/mK were obtained.     

Preparation of syntactic carbon foam

A pressure molding technique for preparing syntactic carbon foam having high compressive strength and low bulk density (> 500 lb/in² at 0·18 g/cm³) is described. The use of hollow phenolic resin and carbon microspheres of various types, particle size, and wall thickness, along with different carbonaceous binder materials, solvents, and molding pressures prior to coking at 900°C were some of the major variables investigated in relation to compressive strength and density characteristics of the syntactic carbon foams.     

Mechanical characterization of new glass fiber reinforced epoxy composites

Glass fiber reinforced plastic (GFRP) composites were made using CTPEGA [carboxyl terminated poly(ethylene glycol) adipate] modified epoxy as a matrix and characterized for their flexural properties, impact strength and interlaminar shear stress (ILSS). The volume fraction of glass was about 0.45 for all the composites. The concentration of CTPEGA in the matrix was varied gradually from 0 to 40 phr (parts per hundred parts of resin), to investigate the effect of CTPEGA concentration on the mechanical properties of the composites. It was found that the flexural strength and ILSS gradually decreases with increase in CTPEGA concentration. However, the impact strength of the composites increases up to 20 phr of CTPEGA concentration and decreases thereafter. Scanning electron microscope (SEM) analysis of the fracture surface indicates massive plastic deformation in modified epoxy based composites. Polym. Compos. 25:165–171, 2004. © 2004 Society of Plastics Engineers.     

Mechanical and dynamic mechanical properties of epoxy syntactic foams reinforced by short carbon fiber

Epoxy syntactic foams were prepared with diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin, 2.4.6‐tri(dimethylaminomethyl)phenol (DMP‐30), coupling treated microsphere and short carbon fiber. The density of the foam was maintained between 0.56 and 0.91 g/cm³ for all compositions. Compressive, flexural, tensile and dynamic mechanical properties of the foams were investigated with respect to hollow glass microsphere (HGM) and carbon fiber (CF) content. A considerable improvement in the mechanical properties viz. compressive, flexural and tensile strengths was observed for the foams on incorporation of a small quantity of CF. The storage modulus were higher for the foam composites containing CF. The presence of HGM has significant influence on T_g of the syntactic foams, spherical filler diminished the T_g of the syntactic foams due to the plasticizing effect of the coupling treatment of HGM, that is helpful for enhancing damping properties of syntactic foams. POLYM. COMPOS., 37:1960–1970, 2016. © 2015 Society of Plastics Engineers     

Processing and performance evaluation of hollow microspheres filled epoxy composites

Microspheres filled epoxy composites are fabricated, using two types of hollow glass microspheres, namely, Fillite‐500 and K‐15. Fillite‐500 microspheres are relatively stronger and denser (avg. crushed strength ∼17 MPa and density ∼0.45 kg/m³) than K‐15 microspheres (avg. crushed strength ∼2 MPa and density ∼0.15 kg/m³). Each type of microspheres in the range of 10–70 vol% are added into a low viscosity two‐part epoxy resin (SC‐15) system in several steps and are mixed together meticulously to avoid breakage of the microspheres during mixing. The epoxy/microspheres mixture is then cured at room temperature (about 70°F) inside an oven for 24 h followed by post curing at 200°F for 4 h. One of the objectives of this research is to determine the maximum amount of microspheres that can be mixed uniformly without aid of diluents. Microstructural examinations reveal that the microspheres are fairly distributed uniformly through out the epoxy matrix up to 70 vol% for Fillite‐500 and 60 vol% for K‐15. It is found that addition of microspheres results in the reduction of density of the neat epoxy up to 28% with Fillite‐500 and up to 54% with K‐15. Thermo mechanical analysis results show that the coefficient of thermal expansion of epoxy matrix is reduced up to 66% with Fillite‐500 and up to 51% with K‐15.Compressive behavior for the epoxy/Fillite‐500 system is found to be different than the epoxy/K‐15 system. Failure analysis results indicate that the failure processes are also different for both the systems. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Preparation and characterization of EVAL hollow fiber membrane adsorbents filled with cation exchange resins

EVAL hollow fiber membrane adsorbents filled with powder D061-type cation exchange resin were prepared through dry-wet spinning process, using hydrophilic copolymer EVAL as the fiber substrate. The microstructures of the membrane adsorbents were observed, and the pure water fluxes, BSA rejection, and static adsorption capacities of membrane adsorbents for BSA were measured. The effect of the resin-filled content on membrane performance has been discussed. The results showed that EVAL hollow fiber membrane adsorbents filled with D061-type cation exchange resins had good adsorption capacity, and the adsorption capacity increased with the quantity of the resin-filled content. The static protein adsorption capacity was 77.14 mg BSA/g membrane adsorbents when D061 resin loading content was 65% at pH 4.5.     

Preparation and characterization of braided tube reinforced polyacrylonitrile hollow fiber membranes

Polyacrylonitrile (PAN) and polyester (PET) braided hollow tube that used as a special reinforcement are braided from their filaments via two‐dimensional weaving techniques. PAN braided tube reinforced homogeneous PAN hollow fiber membranes and PET braided tube reinforced heterogeneous PAN hollow fiber membranes are prepared by concentric circles squeezed‐coated spinning method. As for PAN hollow fiber membrane, the effects of PAN concentration on the performance of the prepared hollow fiber membranes are investigated in terms of pure water flux, protein rejection, mechanical strength, and morphology observations by a scanning electron microscope (SEM). The interfacial bonding state of the braided tube reinforced PAN hollow fiber membranes is studied by constant speed stretching method. Results show that the breaking strength of two‐dimensional braided tube reinforced PAN hollow fiber membranes is higher than 80 MPa. The structure of separation surface is similar to the structure of an asymmetric membrane. With the increase of polymer concentration, the membrane flux decreases while the retention rate of BSA increase. The membrane porosity and maximum pore size have the same decreasing tendency as the increase of PAN concentration. The results also show that the interfacial bonding state of the PAN two‐dimensional braided tube reinforced homogeneous PAN hollow fiber membranes is better than that of the PET two‐dimensional braided tube reinforced heterogeneous PAN hollow fiber membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41795.     

Processing,characterization, and erosion wear characteristics of borosilicate glass microspheres filled epoxy composites

In spite of significant research done in the field of particulate filled polymeric composites, reports on polymers filled with glass microspheres have been extremely rare. In view of this, the present work includes the processing, characterization, and erosion wear response of a new class of epoxy composites filled with different proportions of borosilicate glass microspheres. Hand lay‐up technique is used for making these composites in a laboratory scale. Various physical and mechanical properties are evaluated under controlled laboratory conditions. It is found that while the tensile and flexural strength are marginally influenced, the impact strength is improved quite significantly. Besides, multifold enhancement in composite microhardness is also noticed. Erosion trials are made as per the experimental design based on Taguchi's L₁₆ orthogonal array. Parametric appraisal of erosion process is made and influential parameters affecting the wear rate predominantly are identified. The results indicate that erosion wear rate of these composites is influenced more significantly by impact velocity and filler content respectively compared to others factors. The eroded composite samples are studied using scanning electron microscopy and possible wear mechanisms are discussed. POLYM. COMPOS., 36:1685–1692, 2015. © 2014 Society of Plastics Engineers     

Preparation and characterization of EVAL hollow fiber membrane adsorbents filled with cation exchange resins

EVAL hollow fiber membrane adsorbents filled with powder D061-type cation exchange resin were prepared through dry-wet spinning process, using hydrophilic copolymer EVAL as the fiber substrate. The microstructures of the membrane adsorbents were observed, and the pure water fluxes, BSA rejection, and static adsorption capacities of membrane adsorbents for BSA were measured. The effect of the resin-filled content on membrane performance has been discussed. The results showed that EVAL hollow fiber membrane adsorbents filled with D061-type cation exchange resins had good adsorption capacity, and the adsorption capacity increased with the quantity of the resin-filled content. The static protein adsorption capacity was 77.14 mg BSA/g membrane adsorbents when D061 resin loading content was 65% at pH 4.5.     

Fabrication and characterization of novel zirconia filled glass fiber reinforced polyester hybrid composites

Novel hybrid glass fiber reinforced polyester composites (GFRPCs) filled with 1‐5 wt % microsized zirconia (ZrO₂) particles, were fabricated by hand lay‐up process followed by compression molding and evaluated their physical, mechanical and thermal behaviors. The consumption of styrene in cured GFRPCs was confirmed by Fourier transform infrared spectroscopy. The potential implementation of ZrO₂ particles lessened the void contents marginally and substantially enhanced the mechanical and thermal properties in the resultant hybrid composites. The GFRPCs filled with 4 wt % ZrO₂ illustrated noteworthy improvement in tensile strength (66.672 MPa) and flexural strength (67.890 MPa) while with 5 wt % ZrO₂ showed 63.93% rise in hardness, respectively, as compared to unfilled GFRPCs. Physical nature of polyester matrix for composites and an improved glass transition temperature (T_g) from 103 to 112 °C was perceived by differential scanning calorimetry thermograms. Thermogravimetric analysis revealed that the thermal stability of GFRPCs was remarkably augmented with the addition of ZrO₂. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43615.     

Electrical properties and morphology of polypropylene/epoxy/glass fiber composites filled with carbon black

The volume resistivity and percolation thresholds of carbon black (CB) filled polypropylene (PP), PP/epoxy, and PP/epoxy/glass fiber (GF) composites were measured. The morphology of these conductive polymer composites was studied with scanning electron microscopy (SEM). The effects of the GF and epoxy contents on the volume resistivity were also investigated. The PP/epoxy/GF/CB composite exhibited a reduced percolation threshold, in comparison with that of the PP/CB and PP/epoxy/CB composites. At a given CB content, the PP/epoxy/GF/CB composite had a lower volume resistivity than the PP/CB and PP/epoxy/CB composites. SEM micrographs showed that CB aggregates formed chainlike structures and dispersed homogeneously within the PP matrix. The addition of the epoxy resin to PP resulted in the preferential location of CB in epoxy, whereas in the PP/epoxy/GF multiphase blends, because of the good affinity of CB to epoxy and of epoxy to GF, CB particles were located in the epoxy phase coated on GF. The decreased percolation threshold and volume resistivity indicated that conductive paths existed in the PP/epoxy/GF/CB composite. The conductive paths were probably formed through the interconnection of GF. Appropriate amounts of GF and epoxy should be used to decrease the volume resistivity and provide sufficient epoxy coating. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1142–1149, 2005     

Preparation and characterization of epoxy/carbon fiber composite capacitors

Capacitors based on structural carbon fiber electrodes and epoxy‐based gel polymer electrolyte have been fabricated. The electrochemical properties of electrolytes and capacitors were evaluated by linear sweep voltammetry, cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. Surface modification of carbon fibers was carried out by oxidation, and the structural and surface characteristics of carbon fibers were investigated by scanning electron microscope, Brunauer–Emmet–Teller, and Boehm titration. The results showed that the electrochemical stability window of the electrolyte reached 2.75 V and the ionic conductivity reached the order of 10⁻⁵ S/cm at room temperature. Surface modification of carbon fiber by oxidation can enlarge fiber area and strengthen fiber chemical activity, as well as its energy storage ability. The specific capacitance of epoxy/carbon fiber composite capacitor was obtained as high as 3.0 F/g with good cycling performance. POLYM. COMPOS., 36:1447–1453, 2015. © 2014 Society of Plastics Engineers     

Use of hollow glass microspheres in organosilicon syntact foam plastics

The use of hollow glass microspheres in syntact foam plastics with organosilicon binders is described. The physicomechanical and thermophysical properties of the heat-insulating materials obtained are investigated. Translated from Steklo i Keramika, No. 2, pp. 11–12, February, 2000.     

Mechanical characterization of carbon fiber reinforced phenolic resol and epoxy condensate plastic

A matrix resin for carbon fiber reinforced composite was developed that consisted of resol type phenolic and difunctional epoxy resin (PR-EP) condensate or adduct. Carbon fiber reinforced composite with fiber volume fraction of 0.6 was prepared with PR-EP matrix containing 0, 50, 100, 150, and 175 parts of epoxy resin per hundred parts of phenolic resin (php), especially a synthesized resol type. One-shot and prepreg techniques have been adopted and the study of loss of volatiles has indicated the superiority in terms of favorable processability of prepreg technique over the other. FTIR spectroscopic analysis confirmed the PR-EP adduct formation at the prepreg preparation stage. The improvement in properties such as tensile strength and elongation at break was observed in resin matrices with epoxy and phenolic resin; however, the flexural strength and modulus remained more or less unaltered. The prepreg technique of composite preparation has resulted in substantial improvement in mechanical properties and the same was attributed to the formation of PR-EP adduct and low volatiles during cure. Composites of carbon fiber reinforced PR-EP matrix developed here are likely to meet the requirement of aerospace structures in view of the realization of a wide spectrum of properties.     

镀银空心玻璃球填充的导电有机硅密封剂的研究

以镀银玻璃球为导电填料制备室温硫化高导电有机硅密封剂,研究了密封剂的导电性能与形变的关系:在一定的导电填料加入量范围内,密封剂的导电性能随着拉伸形变而提高。     

High-damping polyurethane/hollow glass microspheres sound insulation materials: Preparation and characterization

The high-damping property of polyurethane elastomers and the low density of the hollow glass microspheres (HGM) were used to prepare the sound insulation materials in the present work. The transmission loss (TL) was measured to evaluate the HGM content on the sound insulation properties. The experimental results showed that the addition of HGM improved the hardness and compression modulus of the HGM-filled polyurethane composites, and the loss factor (tan δ) of polyurethane composites were greater than 0.9. The average transmission loss (ATL, from 63 to 6300 Hz) reached 37.32 dB when the content of HGM was 10 wt%. The ATL of the HGM-filled polyurethane composites with 15 wt% HGM in the damping control region and the mass control region were 31.94 and 46.78 dB, respectively. The synergistic effect of the microphase separation, the interfacial effect and the rigidity of polyurethane composites resulted in the improvement on sound insulation property. The polyurethane composite has a great potential application for the field of sound insulation materials.     

空心玻璃微珠/环氧复合材料的制备及性能研究

制备了空心玻璃微珠/环氧复合材料。通过力学性能、固化收缩率、热性能等测试考察了空心玻璃微珠粒径、填充量、硅烷偶联剂处理对树脂及固化物性能的影响。结果表明,硅烷偶联剂改善了空心玻璃微珠与树脂基体的相容性。复合材料的力学性能随着空心微珠粒径减小而增大。随着空心微珠填充量的加大,固化物拉伸强度有所降低,冲击强度和弯曲强度在空心玻璃微珠质量分数为2%时达到最大值,比纯树脂分别提高了30%和34.2%,同时材料的固化收缩率和密度降低,玻璃化转变温度升高。