Filler Surface Treatment Research Articles

Modification of filler surface treatment of composite resins using alternative silanes and functional nanogels

ObjectivesThis study probes how modifiedapproaches for filler surface treatment in dental composites based on alternative silanes and functional nanogel additives affects physicochemical properties of these materials with a focus on polymerization stress development. MethodsNanogels were synthesized from isobornyl methacrylate, ethoxylated bisphenol-A dimethacrylate and isocyanatoethyl methacrylate followed by partial further reaction with 2-hydroxyethyl methacrylate to provide both isocyanate and methacrylate functionalization. A barium glass filler (˜1 μm particle size) was treated with either γ-methacryloxypropyltrimethoxysilane (MPS), N-methylaminopropyltrimethoxy (MAP) or N-allylaminopropyltrimethoxy (AAP) silanes. The reactive nanogels were then covalently attached to the aminosilane-treated fillers. Surface treatment was characterized by thermogravimetric analysis (TGA) and diffuse reflectance infrared spectroscopy (DR-IR). Composites were formulated with 60 wt% of the various functionalized fillers and the materials were evaluated for polymerization kinetics, polymerization stress (PS), volumetric shrinkage, mechanical properties and photorheology. Data were evaluated by one-way ANOVA and Tukey’s test at 5% significance level. ResultsFiller surface treatments were confirmed by TGA and DR-IR analyses. Nanogel-functionalized fillers significantly reduced PS up to 20%, while the degree of conversion and elastic modulus were not compromised. Similar storage modulus development during polymerization was observed among materials by photorheology although the rate of polymerization was significantly increased for nanogel-based treatments. A significant decrease in flexural strength was observed for amino functional silane groups; however, there was no statistical difference in strength for the MPS control group compared with the nanogel-modified composites. SignificanceFiller surface treatment modified with a reactive nanogel enables significant PS reduction, without compromise to degree of conversion or mechanical properties of dental composites.

On the Role of Solid Lubricant Fillers in the Tribological, Micromechanical, and Morphological Properties of PA66 Composites

Abstract To achieve thermoplastics-based composites with high tribological performances, molybdenum disulfide (MoS2) and graphite (Gr) were incorporated separately to a polyamide 66 (PA66) matrix. Two different development methodologies of composites were used. The morphological features and the micro-mechanical properties of composites were investigated to stress the influence of the filler surface treatment and its dispersion. The friction coefficient was evaluated using a ball on a flat micro-tribometer. The wear mechanisms were also characterized. The best tribological performance was exhibited by 10 wt% of graphite. The surface treatment of the filler inclusions by 3-aminopropyltriethoxysilane (AMPTES) showed an improvement in the morphological aspects of adhesion at the filler/matrix interface.

The effect of titanate nanotube/Y2W3O12 hybrid fillers on mechanical and thermal properties of HDPE-based composites

Hybrid fillers have triggered significant research in the field of polymer-based composites because they offer a range of properties that cannot be achieved by a single filler. Here a novel hybrid filler comprised of titanate nanotubes (TTNT) and Y2W3O12, a thermomiotic ceramic, was incorporated into a high density polyethylene matrix (HDPE) at an extremely low concentration (2 mass %). The influence of TTNT/Y2W3O12 mass ratio (1:1, 1:2 and 2:1), surface treatment of hybrid filler with cetyltrimethylammonium bromide (CTAB) and chemical modification of HDPE with polyethylene-grafted maleic anhydride (PE-g-MA), on the resulting mechanical and thermal properties of HDPE-based composites was investigated. The largest increase (25%) in Young’s modulus and the greatest reduction (23%) in coefficient of thermal expansion (CTE) of HDPE was achieved for 2:1 TTNT/Y2W3O12 mass ratio, without significant alteration of thermal degradation beginning or thermal conductivity of HDPE. At this optimum TTNT/Y2W3O12 mass ratio, CTAB treatment of fillers was more efficient than PE-g-MA modification of matrix promoting a better dispersion of TTNT/Y2W3O12, leading to an increase of 34% in composite stiffness and a CTE reduction of 18%, although both treatments improved hybrid filler-matrix interfaces, as judged by a rise of 6% in yield strength.

Effect of cenosphere filler surface treatment on the erosion behavior of epoxy matrix syntactic foams

Influence of cenosphere surface modification and volume fraction on the solid particle erosion of cenosphere/epoxy syntactic foams is investigated. Fly ash cenospheres are used as filler in both as received and silane surface modified configurations. Erosion behavior is studied at room temperature for different impact angles (30, 45, 60, and 90°) and velocities (30, 45, and 60 m/s). Neat epoxy shows the highest erosion rate compared with that of the syntactic foams. Results show a strong dependence of impact angle and velocity on erosion rate of syntactic foams. With increasing cenosphere content erosion rate decreases for all impact angles. Erosion rate decreases with increasing impact angle and with decreasing velocity. Good interfacial bonding of treated cenospheres enhances the erosion resistance. All the samples exhibit ductile erosive behavior, with maximum erosion at 30°. The velocity exponent and erosion efficiency parameters confirm the ductile behavior of syntactic foams. POLYM. COMPOS., 40:2109–2118, 2019. © 2018 Society of Plastics Engineers

Tailored surface chemistry of SiO2 particles with improved rheological, thermal-mechanical and adhesive properties of epoxy based composites for underfill applications

Recently, the silica particles filled epoxy-based composites underfill has gained more and more attentions with the development of flip chip technology towards high density and fine-pitch. However, serious agglomeration and poor dispersion of SiO2 in polymer matrix inevitably leads to deterioration of the rheological and thermal-mechanical properties. The filler surface treatment technology has been well demonstrated to be effective in controlling interfacial compatibility and interfacial interaction of their filled composites and thus enhancing their mechanical properties. However, the role of surface characteristics of SiO2 fillers on the properties associated with underfill such as rheological, coefficient of thermal expansion (CTE) as well as adhesive strength has been rarely reported. In this paper, surface modification of SiO2 particles have been conducted using silane coupling agents with various functional groups. We have attempted to establish a qualitative structure-property relationship between microscopic filler surface chemistry and macroscopic properties of the resulting composites underfill. The results showed that surface modification enabled to decrease underfill viscosity obviously and surface modification with nonpolar groups, such as methacryloxy and phenyl groups showed a much higher efficiency for viscosity reduction than their polar groups counterparts, such as amino and epoxy groups. Meanwhile, underfill with these nonpolar groups modified SiO2 exhibited much higher adhesion strength, accompanied by a conversion of failure mode from the adhesive failure to cohesion failure. In contrast, surface modification with those polar groups was more beneficial to decrease CTE of composites underfill. Our work is believed to be of great value for the design of SiO2 particle-based composites underfill with tailored properties.

Ionic Liquid Surface Treatment of Calcite for Improved Compatibility with Polyolefin Matrix

Preliminary surface treatment of crystalline marble powder filler with a dominatingly hydrophobic ionic liquid, namely triethylsulfonium-bis(trifluoromethylsulfonyl) imide has been employed to design a filler with improved compatibility towards non-polar polymer matrices, such as polyolefins. The maximum uptake of ionic liquid per 1g of marble powder was 132 mg. The surface coating of the crystalline phases has been proved by XRD and FTIR spectroscopy, making our method useful in designing fillers with improved dispersibility/ compatibility in/with polyolefins. The floating test method has proved the efficiency of the alkylsulfonium ionic liquid in hydrophobization of the crystalline calcite-rich phase, thus proving useful in obtaining composites with improved properties.

Obtaining and Characterization of Polyolefin-Filled Calcium Carbonate Composites Modified with Stearic Acid

In order to obtain high performance calcium carbonate-reinforced HDPE and PP composites, the dispersibility and compatibility of the inorganic phase in the polymer has been achieved through surface treatment of the amorphous calcium carbonate filler with stearic acid. The surface coating of the inorganic phase has been proved by XRD and FTIR spectroscopy, through forming of an intermediate layer of calcium stearate which acts as a surfactant, efficient in providing an optimum compatibility with the dominatingly hydrophobic polymer matrix, as determined from the structural information obtained through samples cross-sections analysing.

The effect of mechano-chemical activation and surface treatment of limestone filler on the properties of construction composites

Abstract The effect of the combined actions of milling and hydrophobization procedures applied in construction composites synthesis was investigated. The mortars were prepared with cement (CEM I 42.5) and calcite aggregate complying the standard 1:3 mix ratio. The limestone filler (10 wt%) was added to the mixture upon its mechano-chemical activation in an ultra-centrifugal mill. The activation variables (milling time, rotor velocity, sieve mesh size) were altered to achieve the optimal quality of the powder. The treatment was optimized via chemometric tools. The r2 values (0.955–0.998) of second order polynomial models accurately predicted the output and the Standard score analysis chose the optimal activation parameters: 4.25 min; 48.58 m/s and 80 μm sieve. The selected filler and all three aggregate fractions were coated with stearic acid via dry procedure. The mortar mixes, prepared with uncoated (M1) and coated (M2) aggregate and filler, were cured for a period of 28 days during which compressive strength and water absorption were monitored. The dimensional changes in mortars were estimated via TMA dilatometer measurements. Thermo-analytical methods (DTA/TGA) were applied in the thermal behavior analysis. Mineralogical and morphological changes in the structure of hardened composite were detected by XRD and SEM, respectively. Limestone aggregate led to lower final compressive strengths in mortar, but it produced an infinitesimally small shrinkage at 1000 °C. The hydrophobization via stearic acid initiated the decrease in water absorption and formation of needle-like micro-network that filled structural voids reducing open porosity. The assessment of the effects of limestone utilization as a filler and as an aggregate on the mortar performances confirmed that this novel water-repellent composite is applicable in structural design.

Effect of Silane Coupling Treatment of Filler Surface on Color Stability of Resin Composite

Effect of Silane Coupling Treatment of Filler Surface on Color Stability of Resin Composite

Anionic Nylon 612/TiO2 Composite Materials: Synthesis, Characterization and Properties

Two novel series of composites have synthesized in situ by simultaneous anionic ring-opening copolymerization-rotational molding fast environment-friendly process using e-caprolactam (CL) with laurolactam (LL) as starting comonomers and TiO2 as filler. The type of filler (with surface treated or not) differentiates the two series. Aminopropyl triethoxysilane (APTES) coupling agent was used. By adjusting the TiO2 in the range 0.0–8.0 wt.% in the feed monomers mixture, various composites were obtained. The characterization of samples was performed, in the context of filler type and content variation by combined use of ATR–FTIR spectroscopy, X-ray spectroscopy, DSC, TGA/DTG, SEM and mechanical measurements. In addition, degree of conversion, intrinsic viscosity and water absorption were evaluated. Introduction of the long methylene sequences through the second monomer into the nylon 6 chains improved especially the water uptake of the composites. The melting temperature (Tm), crystallization temperature (Tc), degree of crystallinity (αDSC) and the interface interactions between filler and nylon 612 matrix prove to be improved by treatment of filler surface. The same trend was recorded for tensile strength, tensile modulus, elongation at break and impact strength. The results related to composites were compared with those obtained for neat nylon 612 copolymer synthesized in the same conditions.

The influence of particle size and surface treatment of filler on the properties of oyster shell powder filled polypropylene composites

In this study, properties of oyster shell powder filled polypropylene (OSP/PP) composites were improved by enhancing particle distribution and filler‐matrix interfaces in the composites. The OSP enhances thermal stability and fire retardant properties of polymer composites but it decreases the mechanical strength due to poor interaction with the polymer matrix. OSP is an amorphous powder which agglomerates during distribution. Polyvinyl alcohol (PVA) was used to enhance the interfacial bonding between OSP and PP, while distribution of the OSP particles in composites was improved by varying the particle size of the filler. The effects of particle size and PVA treatment on mechanical properties of composites were studied through experimental tests and finite element analysis. Experimental results and finite element analysis agree to each other, it was observed that small size particles and PVA incorporation resulted in improving properties of OSP/PP composites. Mechanical properties were improved while thermal stability and fire retardancy were further enhanced. Fourier transform infrared spectroscopy revealed a physical interaction between the composite constituents in the presence of PVA. POLYM. COMPOS., 39:2420–2430, 2018. © 2016 Society of Plastics Engineers

Dielectric and piezoelectric properties of percolative three-phase piezoelectric polymer composites

Three-phase piezoelectric bulk composites were fabricated using a mix and cast method. The composites were comprised of lead zirconate titanate (PZT), aluminum (Al), and an epoxy matrix. The volume fraction of the PZT and Al was varied from 0.1 to 0.3 and 0.0 to 0.17, respectively. The influences of an electrically conductive filler (Al), polarization process (contact and Corona), and Al surface treatment, on piezoelectric and dielectric properties, were observed. The piezoelectric strain coefficient, d33, effective dielectric constant, εr, capacitance, C, and resistivity were measured and compared according to polarization process, the volume fraction of constituent phases, and Al surface treatment. The maximum values of d33 were ∼3.475 and ∼1.0 pC/N for corona and contact poled samples, respectively, for samples with volume fractions of 0.40 and 0.13 of PZT and Al (surface treated), respectively. Also, the maximum dielectric constant for the surface treated Al samples was ∼411 for volume fractions of 0.40 and 0.13 for PZT and Al, respectively. The percolation threshold was observed to occur at an aluminum volume fraction of 0.13. The composites achieved a percolated state for Al volume fractions >0.13 for both contact and corona poled samples. In addition, a comparative time study was conducted to examine the influence of surface treatment processing time of aluminum particles. The effectiveness of the surface treatment, sample morphology and composition was observed with the aid of scanning electron microscope and energy dispersive x-ray spectroscopy images. These images were correlated with piezoelectric and dielectric properties.

Tensile behavior of polyolefin composites: the effect of matrix parameters

ABSTRACTPolyolefin composites were prepared from 14 PE matrices and three different mineral fillers (montmorillonite, palygorskite and glass microspheres) via melt compounding in an extruder. Mechanical properties of the obtained systems were analyzed with emphasis on elongation at break and conditions for ductile/brittle failure were determined. When filler content is raised beyond a certain “critical” value, tensile properties are dramatically altered and transition occurs from ductile behavior to brittle fracture. This transition is displayed by a well‐defined “step” on the plot of strain at break versus concentration of particles. The value of “critical filler content” was found to depend mainly on level of crystallinity of a matrix while other parameters (chemical nature of filler particles, their size, shape and surface treatment) are less significant. “Critical filler content” will decrease with growth of crystallinity of a polymer and with highly crystalline HDPEs it is as low as 2–8 vol %. Otherwise, with noncrystallizing and low‐crystalline polymers elongation at break decreases gradually with concentration of mineral particles and ductile type deformation is maintained at fairly large filler fractions. The results presented here will be useful for a proper selection of a matrix polymer in composites with mineral fillers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43819.

Combined Effect of Chemical Surface Treatment of Kevlar Fabric and PTFE Fillers on the Water-Involved Tribological Performance of Kevlar Fabric/Phenolic Laminate

ABSTRACTThe combined effect of chemical surface treatment of Kevlar fabric and solid lubricant polytetrafluoroethylene (PTFE) fillers on the water-involved tribological performance of Kevlar fabric/phenolic resin laminate was investigated. Results showed that the interfacial adhesion between Kevlar fabric and resin was improved because of chemical surface treatment on the Kevlar fabric, leading to a decreased wear rate but an increased friction coefficient of the laminate. The addition of PTFE fillers not only enhanced the wear resistance of the laminate but reduced its friction coefficient. Furthermore, the combination of surface treatment on Kevlar fabric and the PTFE filling can improve the wear resistance and friction-reducing property of the laminate to the largest extent.

Impact and flexural properties of PP/CaSiO3 composites

The effects of filler surface treatment and content on the impact fracture toughness and flexural properties of polypropylene (PP) composites filled with wollastonite (CaSiO3) were investigated. The results showed that the introduction of the filler could toughen and reinforce the PP; the influences of the filler surface treatment on the toughness and strength were significant; the values of the Izod V‐notched impact strength and the Charpy V‐notched impact strength of the composites increased with increasing the filler weight fractions; the values of flexural modulus increased with increasing the filler weight fractions; the flexural strength increased when the filler weight fraction was lower than 10% and then varied slightly. This toughening effect should be attributed to the stress concentration because of strip shape of the filler and to block the development of the notched cracks in the matrix, improving the notched sensitivity to the impact fracture of the PP composites. This study should be helpful to understand the mechanisms of CaSiO3 reinforcing and toughening PP resin. POLYM. COMPOS., 39:398–404, 2018. © 2016 Society of Plastics Engineers

Surface modification of halloysite nanotubes by vulcanization accelerator and properties of styrene-butadiene rubber nanocomposites with modified halloysite nanotubes

Vulcanization accelerant N-cyclohexyl-2-benzothiazole sulfenamide (CZ) was used as a surface modifier and chemically grafted on the surface of halloysite nanotubes (HNTs) to obtain CZ-functionalized HNTs (HNTs-s-CZ). It was found that HNTs-s-CZ could be homogeneously dispersed into styrene-butadiene rubber (SBR). The grafted CZ molecules, exactly located at the filler-rubber interface, reduced the activation energy of vulcanization of SBR/HNTs-s-CZ compounds. Besides, the density of chain segments introduced by the interfacial phase of SBR/HNTs-s-CZ nanocomposites was higher than the other nanocomposites with silane-modified HNTs (m-HNTs) or pristine HNTs, manifesting an indication of enhanced filler-rubber interfacial interaction in SBR/HNTs-s-CZ nanocomposites. Consequently, SBR/HNTs-s-CZ nanocomposites showed excellent mechanical properties. The tensile strength could be enhanced by as much as 38.6% and 102.5% compared to those of SBR/m-HNTs and SBR/HNTs nanocomposites, respectively, though containing equivalent accelerant component. The value of this work lies in the fact that apparent properties improvement of elastomer composites has been achieved by the incorporation of vulcanization accelerant-functionalized HNTs, which may be fruitful for the rational design of filler surface treatment and offer new scientific and technological opportunities for the preparation of high performance elastomer composites.

Polymer sand composites based on the mixed and heavily contaminated thermoplastic waste

This paper represents production and characterization of highly filled polymer composites based on recycled plastics and sand as a filler. Composites produced on the bases of polyolefin (polyethylene PE and linear low-density polyethylene LLDPE) and polyester (PET) were compared. Different modification techniques, including filler surface treatment, compatibilizer introduction and polymer blend formation were used. Influence of the composition on the composite mechanical properties was evaluated. Newly developed composite based on PET - polycarbonate (PC) blend demonstrates improved mechanical properties and higher thermal stability compared to polyolefin based composites.

Cellulose nanocrystal reinforced liquid natural rubber toughened unsaturated polyester: Effects of filler content and surface treatment on its morphological, thermal, mechanical, and viscoelastic properties

Cellulose nanocrystals (CNCs) isolated from kenaf bast fibers were used to reinforce unsaturated polyester resin (UPR) composites toughened with liquid natural rubber (LNR). The surface of the CNCs was modified with silane, and the effects of this treatment on the morphological, tensile, and thermal properties of the resulting composites were studied. Electron micrographs show that the CNCs are well dispersed in the UPR and the rubber phase and that the rubber particles are smaller in the nanocellulose composites. Tensile tests show that untreated CNC–LNR–UPR composites are as strong as toughened UPR. The tensile modulus increases significantly with either treated or untreated CNC content of the composites. The impact resistance of UPR increases as LNR and then CNCs are added, with the best results obtained with silane-treated CNCs. The viscoelastic behavior and the thermal resistance of the composites also improve upon addition of both treated and untreated CNCs.

Water Absorption Behavior of Hemp Hurds Composites

In this paper, water sorption behavior of 28 days hardened composites based on hemp hurds and inorganic binder was studied. Two kinds of absorption tests on dried cube specimens in deionized water bath at laboratory temperature were performed. Short-term (after one hour water immersion) and long-term (up to 180 days) water absorption tests were carried out to study their durability. Short-term water sorption behavior of original hemp hurds composites depends on mean particle length of hemp and on binder nature. The comparative study of long-term water sorption behavior of composites reinforced with original and chemically modified hemp hurds in three reagents confirmed that surface treatment of filler influences sorption process. Based on evaluation of sorption curves using a model for composites based on natural fibers, diffusion of water molecules in composite reinforced with original and chemically modified hemp hurds is anomalous in terms of the Fickian behavior. The most significant decrease in hydrophility of hemp hurds was found in case of hemp hurds modified by NaOH and it relates to change in the chemical composition of hemp hurds, especially to a decrease in average degree of cellulose polymerization as well as hemicellulose content.

Bioactivity of cellulose acetate/hydroxyapatite nanoparticle composite fiber by an electro-spinning process.

Hydroxyapatite/cellulose acetate composite webs were fabricated by an electro-spinning process. This electro-spinning process makes it possible to fabricate complex three-dimensional shapes. Nano fibrous web consisting of cellulose acetate and hydroxyapatite was produced from their mixture solution by using an electro-spinning process under high voltage. The surface of the electro-spun fiber was modified by a plasma and alkaline solution in order to increase its bioactivity. The structure, morphology and properties of the electro-spun fibers were investigated and an in-vitro bioactivity test was evaluated in simulated body fluid (SBF). Bioactivity of the electro-spun web was enhanced with the filler concentration and surface treatment. The surface changes of electro-spun fibers modified by plasma and alkaline solution were investigated by FT-IR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy).