Effect of different types of filler and filler loadings on the properties of carboxylated acrylonitrile–butadiene rubber latex films

The effects of different types of fillers and filler loadings on the properties of carboxylated nitrile rubber (XNBR) latex were identified. Silica, mica, carbon black (CB; N330), and calcium carbonate (CaCO₃) were used as fillers with filler loadings of 10, 15, and 20 parts per hundred rubber. Furnace ashing and Fourier transform infrared analysis proved that interaction existed between the fillers and XNBR latex films. The morphology of the filled XNBR films was significantly different for different types of fillers. Mica and CaCO₃ fillers showed uneven distribution within the XNBR film, whereas other fillers, such as silica and CB, showed homogeneous distribution within the films. In the observation, silica and mica fillers also illustrated some degree of agglomeration. The mechanical properties (e.g., tensile and tear strengths) showed different trends with different types of fillers used. For silica and mica fillers, the mechanical properties increased with filler loadings up to a certain loading, and decreased with higher filler loadings. For CB filler, the mechanical properties increased gradually with increasing filler loadings. CaCO₃ fillers did not increase the mechanical properties. The crosslinking density of the XNBR films increased when they were incorporated with fillers because of the presence of elastomer–filler and filler–filler interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal analysis of elastomer composites

Thermal analysis of polychloroprene elastomer composites was carried out. Addition of reinforcing fillers such as precipitated silica (Vulcasil‐S), carbon black (FEF N‐550), and short silk fiber led to significant changes in the degradation pattern, depending on their reinforcement and adhesion ability with the elastomer matrix. Attempts were made to correlate the variations of thermal properties with the surface chemistry and the reinforcement characteristics of these fillers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 646–651, 2001     

Mechanical, rheological, and thermal behavior assessments in HDPE/PA-6/EVOH ternary blends with variable morphology

Visco-elastic and dielectric spectra of multiwalled carbon-nanotube reinforced silicon elastomer nanocomposites were used to study relaxation behavior. SEM photomicrographs shows well dispersion of MWCNT in elastomer matrix. In visco-elastic analysis primary relaxation was studied as a function of temperature (?100 to 100 °C) at frequency 1Hz and strain 1 %. The effect of MWCNT loadings on storage modulus, loss modulus, and loss tangent has been studied. The non-linearity in loss tangent, storage modulus and loss modulus was explained on the basis of MWCNT-elastomer interaction and the inter-aggregate attraction of MWCNT. The secondary β relaxation was studied using dielectric relaxation spectra in the frequency range of 0.1 Hz to 10⁶ Hz. The effect of MWCNT loadings on the complex and real parts of impedance was distinctly visible which has been explained on the basis of interfacial polarization of fillers in a heterogeneous medium and relaxation dynamics of polymer chains in the vicinity of fillers. The dielectric formalism has been utilized to further investigate the conductivity and relaxation phenomenon. The ‘percolation limit’ of the MWCNT in the silicon elastomer was found to be in the range of 4 phr loading.     

Mechanical and rheological properties of silica-reinforced polypropylene/m-EPR blends

Rheological and mechanical properties (tensile and impact properties) as well as the mechanical profiles of ternary isotactic polypropylene/silica/elastomer (iPP/SiO₂/m-EPR metallocene catalyzed ethylene-propylene rubber) composites were investigated and discussed. The effects of two metallocene ethylene-propylene-based elastomers (m-EPR) differing in molecular weight/viscosity and their content on iPP/silica composites with different silica types differing in size (nano- vs. micro-) and surface properties (untreated vs. treated) were investigated. The two m-EPR elastomers were added to iPP/SiO₂ 96/4 composites as possible impact modifier and compatibilizer at the same time in 5, 10, 15, and 20 vol% per hundred volume parts of composites. The effects of different silica fillers and two m-EPR rubbers were discussed within the context of structure-morphology-mechanical property relationships of these iPP/SiO₂/m-EPR composites. Tensile and impact strength properties were mainly influenced by combined competetive effects of stiff filler and tough m-EPR elastomer so sinergistic effect was also observed. The ductility of these composites was affected additionally by spherulite size of the iPP matrix due to the difference in nucleation abilities of silica fillers enabled by prevailing separated morphology observed in iPP/SiO₂/m-EPR composites.     

Morphology,interfacial interaction,and properties of a novel bioelastomer reinforced by silica and carbon black

A novel poly(diisoamyl itaconate‐co‐isoprene) (PDII) bioelastomer was prepared by redox emulsion polymerization based on itaconic acid, isoamyl alcohol, and isoprene. Carbon black (CB), silica, and silica with coupling agent (bis(3‐(triethoxysilyl)‐propyl)tetrasulfide [TESPT]‐silica) were used as fillers to reinforce the novel elastomer. The difference in morphology, interfacial interaction, thermal properties, and mechanical properties of PDII composites filled with different fillers was studied. The homogeneous dispersion of silica and CB in the PDII matrix was confirmed by scanning electron microscopy and transmission electron microscopy. Silica had homogenous dispersion possibly because of the formation of hydrogen bonds between the silica silanols and the PDII macromolecular chains. PDII/silica and PDII/TESTP‐silica have lower crosslink density and crosslinking rate than PDII/CB owing to the adsorption of accelerators by the silanols in the silica surfaces. PDII/silica had comparable tensile strength but higher elongation at break than PDII/CB. The tensile strength of PDII/TESPT‐silica was higher than PDII/CB and PDII/silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

DSC analysis of epoxy molding compound with plasma polymer–coated silica fillers

Silica fillers were modified by plasma‐polymerization coating of 1,3‐diaminopropane, allylamine, pyrrole, 1,2‐epoxy‐5‐hexene, allylmercaptan, and allylalcohol using RF plasma (13.56 MHz). Modified fillers were then mixed with biphenyl epoxy resin, phenol novolac (curing agent), and optionally triphenylphosphine (catalyst) to prepare samples for DSC analyses. Some samples were also prepared from uncoated silica fillers and monomers used in plasma polymerization coating, instead of plasma polymer–coated silica fillers. Plasma polymer–coated silica fillers were characterized by FTIR, XPS, and water contact angle measurements. In DSC analyses, all samples with plasma polymer–coated silica fillers showed a large peak and an additional one or two small exothermic peaks when catalyst was added, compared to only one large peak with as‐received silica fillers. The large peak could be from epoxy–phenol novolac reaction in the presence of catalyst, whereas small reaction peaks were attributed to the chemical reaction between epoxy resin and functional moieties in the plasma polymer coating, such as amine, OH, and/or SH groups, as evidenced by FTIR and XPS analysis and contact angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2508–2516, 2003     

Polypropylene/silica micro‐ and nanocomposites modified with poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)

The effects of different silica loadings and elastomeric content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with 5, 10, 15, and 20 vol % of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) SEBS added to total composite volume were investigated. Four silica fillers differing in size (nano‐ vs. micro‐) and in surface properties (untreated vs. treated) were chosen as fillers. Elastomer SEBS was added as impact modifier and compatibilizer at the same time. The morphology of ternary polymer composites revealed by light and scanning electron microscopies was compared with morphology predicted models based on interfacial properties. The results indicated that general morphology of composite systems was determined primarily by interfacial properties, whereas the spherulitic morphology of polypropylene matrix was a result of two competitive effects: nucleation effect of filler and solidification effect of elastomer. Tensile and impact strength properties were mainly influenced by combined competetive effects of stiff filler and tough SEBS elastomer. Spherulitic morphology of polypropylene matrix might affect some mechanical properties additionally. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41486.     

Oil shale solid waste recycling in the development of new silica fillers for elastomeric composites

The production of Brazilian shale oil gives rise to 6600 ton/day of a solid waste of retorted shale, and larger amounts of dolomitic waste rock are generated during mining. Two vitreous materials were obtained through the melting of different proportions of these two wastes. By leaching these materials with hydrochloric acid at 90°C, two different kinds of silicas (powder and gel, both amorphous) with specific surface areas reaching up to ～ 420 m²/g were generated. These silicas were further modified through an Ostwald‐ripening type of treatment in ammonium hydroxide solution at 80°C. The process eliminated almost completely the deleterious micropores. The obtained silicas were evaluated as reinforcing fillers for SBR‐1502. The employment of one of the modified silicas gave rise to a composite with better mechanical properties than those displayed by the one with untreated silica. Scanning electronic microscopic observation disclosed the existence of great morphological differences between these silicas. Apparently, the aging treatment gave rise to the production of better anchoring sites for the elastomer molecules. NMR studies also showed the reduction of the silanol content of the treated silica. The fracture surface of the composite disclosed a good wetting of this silica by the elastomeric matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2856–2867, 2001     

Functional lignin-SiO2 hybrids as potential fillers for phenolic binders

Functional lignin-SiO₂ hybrid fillers were synthesized and characterized with a view to their potential application in binders for phenolic resins. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin or silica alone. The chemical structure of the materials was investigated by Fourier transform infrared spectroscopy. Surface properties of lignin-SiO₂ fillers were tested using inverse gas chromatography (IGC). IGC was used for determination of surface energy and surface heterogeneity of the studied fillers. IGC made it possible to assess the adhesion between the tested fillers and phenolic resins. Interactions of functional fillers with phenolic resins were also evaluated by IGC. The results indicated that lignin-SiO₂ interacted strongly with the phenolic resin, more strongly than pure lignin. This was proved by SEM observations: thanks to the stronger interactions of lignin-SiO₂ hybrid with phenolic resins, a more homogeneous composite was obtained. Thermo-mechanical properties of lignin–silica and resin systems were investigated by DMTA. DMTA results showed that phenolic binders with lignin-SiO₂ fillers have better thermo-mechanical properties than systems with lignin or silica alone: higher glass transition temperature and a smaller decrease in storage modulus. Lignin fillers can thus provide new, promising properties for a phenolic binder combining the good properties of lignin as a plasticizer and of silica as a filler improving mechanical properties.     

Effect of different fillers on physical,mechanical, and optical properties of styrenic‐based thermoplastic elastomers

The effects of different fillers on physical, mechanical, and optical properties of styrenic‐based thermoplastic elastomers were investigated by experimental study. Poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] block copolymer (SEBS)‐based thermoplastic elastomer composites were prepared in a co‐rotating intermeshing twin‐screw extruder, using silica and calcite as filler materials with three different particle sizes. The loading ratios in the composites were varied. Hardness, density, tensile strength, tear strength, compression set, wear resistance, transmittance, and haze measurements were performed. Thermal properties and morphological structure were investigated by differential scanning calorimeter (DSC) and scanning electron microscopy (SEM), respectively. The results show that, an interaction between silica and the polymer matrix exists, whereas calcite does not show any interaction with the polymer. Therefore, it is concluded that, calcium carbonate can be used in the composite as filler for cost efficiency, whereas silica can be used as reinforcing material in SEBS‐based thermoplastic elastomer composites, when optical properties are also concerned. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Silicone rubbers for dielectric elastomers with improved dielectric and mechanical properties as a result of substituting silica with titanium dioxide

One prominent method of modifying the properties of dielectric elastomers (DEs) is by adding suitable metal oxide fillers. However, almost all commercially available silicone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler. We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler. Liquid silicone rubber (LSR) has relatively low viscosity, which is favorable for loading inorganic fillers. In the present study, four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber (RTV) were investigated. The resulting elastomers were evaluated with respect to their dielectric permittivity, tear and tensile strengths, electrical breakdown, thermal stability and dynamic viscosity. Filled silicone elastomers with high loadings of nano-sized titanium dioxide (TiO₂) particles were also studied. The best overall performing formulation had 35 wt.% TiO₂ nanoparticles in the POWERSIL® XLR LSR, where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz, breakdown strength of 160 V µm^?1, tear strength of 5.3 MPa, elongation at break of 190%, a Young’s modulus of 0.85 MPa and a 10% strain response (simple tension) in a 50 V μm^?1 electric field was obtained.     

Polymer–filler interaction in polyurethane kraft lignin polyblends

Kraft lignin fillers have been shown to enhance the mechanical characteristics of different types of polymeric-based sealants; however, the mechanism for reinforcement and the degree of interaction was not well understood. In this study, interactions between a polyurethane-based elastomer and various Kraft lignin fillers as well as kaolin and titanium dioxide filler combinations were investigated in an effort to determine the most useful elastomer–filler combination for use as a construction joint sealant. A relationship that describes and relates the characteristics of polymer–filler interaction requires that the surface-energy properties of both the polymer matrix and the filler be determined. Measurements using the sessile drop method are used to evaluate the critical surface energy of the polymer matrix, whereas the rate of rise of a liquid through a bed of filler provides the means to evaluate the surface energetics of the various fillers. Results obtained from this study show that the tensile modulus of the different elastomer formulations are proportional to the equilibrium work of adhesion, as described by the relationship derived by Lee that relates the degree of interaction of the formulation components and the mechanical properties of the blends. © 1994 John Wiley & Sons, Inc.     

Ternary‐phase poly(ester‐urethane)/elastomer/filler composites

Impact‐modified and reinforced composites, consisting of biodegradable poly(ester‐urethane) (PEU), poly(L ‐lactic acid‐co‐ϵ‐caprolactone‐urethane) elastomer, and various organic and inorganic fillers, were prepared by melt blending, and their properties were investigated. The impact strength increased with elastomer addition, and the addition of particulate or fibrous fillers as a third component increased the stiffness. Therefore, the balance between the impact strength and stiffness of the amorphous PEU was significantly improved. Composites with elastomer and 15 wt % particulate fillers, that is, wollastonite, Aktisil, and talc, showed excellent impact strength. However, effective impact modification was lost in highly constrained systems. Dynamic mechanical thermal analysis confirmed the phase separation of elastomer and showed a marked increase in the glass‐transition temperature for the PEU matrix in binary blends with wollastonite, talc, and glass fiber. Scanning electron microscopy studies showed good adhesion of the components. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1531–1539, 2001     

In-situ precipitation of reinforcing titania fillers

Summary The technique developed for precipitating reinforcing silica into an elastomer is extended to titania fillers by hydrolyzing a titanate instead of a silicate. Of the three catalysts studied, namely HCl, NH₄OH, and (C₂H₅)₂NH, the NH₄OH was the most efficient, introducing as much as 65 wt % titania into a poly(dimethylsiloxane) network in twelve hours. Stress-strain measurements in elongation showed the nature and extent of the reinforcement to be very similar to that obtained from insitu precipitated silica.     

Morphology and Mechanical Properties of iPP/Silica Composites Modified with (Styrene-b-ethylene-co-butylene-b-styrene) Grafted with Maleic Anhydride

The effects of different silica grades and elastomer content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with added 5, 10, 15, and 20% of poly(styrene-b-ethylene-co-butylene-b-styrene) grafted with maleic anhydride (SEBS-g-MA) were investigated. The iPP/silica/SEBS-g-MA composites were designed by adding four silica fillers differing in size (nano- vs. micro-) and in surface properties (hydrophilic vs. hydrophobic) and SEBS-g-MA that was used as a proven effective impact modifier and compatibilizer simultaneously. The morphology of every composite was a spectrum of several morphologies rather than one exclusive morphology. Good concordance between observed and predicted morphology indicated that the morphology of a particular composite was controlled primarily by interfacial properties. Tensile and impact properties were influenced primarily by competitive effects of a stiff filler and tough SEBS-g-MA elastomer. Increased impact strength and strain at break caused by adding SEBS-g-MA indicated a significant overcoming of the elastomeric toughening effect in relation to the filler’s stiffening effect.     

IGC study of filler–filler and filler–rubber interactions in silica‐filled compounds

A modification of the existing methods for evaluating the dispersive and specific components of surface free energy (γ_d and γ_s, respectively) was made to investigate filler–rubber and filler–filler interactions by inverse gas chromatography. Four silicas as fillers and various probes that mimic elastomers were employed in this study. It was shown that the pretreatment of silicas with helium could increase γ_d and decrease γ_s. Modification of the silica surface with silane could enhance the dispersive interaction and weaken the specific interaction. The temperature dependence of the interfacial interaction was also investigated, and it was found that lower temperatures favored filler–rubber interactions and mixing efficiency. Tests on different sizes of agglomerates demonstrated the existence of a filler–rubber and filler–filler network. It was also found that γ_d played a role in agglomeration or filler–filler interaction. Our study showed that the larger the specific surface area was, the stronger the dispersive and specific interactions were. The effectiveness of various fillers and elastomer probes was also compared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2517–2530, 2001     

Synthesis of silica-coated graphite by enolization of polyvinylpyrrolidone and its thermal and electrical conductivity in polymer composites

Silica-coated graphite flakes, which have electrical insulating property and high thermal conductivity, were synthesized by a polyvinylpyrrolidone (PVP)-assisted sol–gel reaction. The critical role of keto-enol tautomerism of PVP in base-catalyzed silica sol–gel reaction was elucidated. The degree of silica coating on graphite was controlled by the amount of PVP and silica precursor, tetraethyl orthosilicate. The silica-coated graphite was used as a filler in thermoplastic polyester elastomer (TPEE). The in-plane (Λ) and through-plane (Λ_⊥) thermal conductivity values of silica-coated graphite/TPEE composites are 67.5% and 86.6% of those of raw graphite/TPEE at 80 phr loading. Even after a severe mixing process under high shear at elevated temperature, silica-coated graphite/TPEE composites retain the perfectly insulating surface resistivity of >10¹³ Ω/sq up to high filler contents.     

Proton conducting materials based on thermoplastic elastomers silica composites

In this research, ionomeric composites based on organophilized silica (SIL) and a thermoplastic elastomer (HSBR), were prepared and characterized from a microstructural and electrical point of view. DSC was used to confirm silica sulfonation and FTIR to characterize the polymer before and after sulfonation reaction. DSC and DMA analysis show that T_g^HPB remains constant in all the samples studied. T_g^PS measured through DMA presents an increase of about 40°C in the sample containing both the sulfonated filler and the sulfonated polymer matrix. The resulting materials can be easily processed to yield thin films (thickness 0.2–0.4 mm) with outstanding proton conducting properties (10^?2 S · cm^?1). The suitability for film formation and good electrical properties is indicative of their potential use as electrolytes in polymer fuel cells. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2715–2720, 2003     

Improvement of interfacial interaction,dispersion, and properties of chlorosulfonated polyethylene/sio2 nanocomposites using CSPE‐g‐Sio2 nanoparticles synthesized under ultrasonics

Chlorosulfonated polyethylene (CSPE) is a widely used elastomer because of the resistance to gases and aggressive chemicals, fire‐retarding, and electric insulating properties. Silica nanoparticles were usually introduced into the elastomer to improve its critical properties. However, there were some problems of strong aggregation and poor dispersion of nanoparticles in the nanocomposites. In this work, an efficient approach of grafting matrix CSPE onto silica surface was proposed to solve the problems. CPSE‐g‐SiO₂ nanoparticles were prepared via an in situ radical reaction between  Cl in CSPE and Si OH on silica surface under ultrasonics. The successful chemical graft reaction was confirmed using Fourier transform infrared, ultraviolet–visible spectroscopy, ¹H‐NMR, and X‐ray photoelectron spectroscopy. Thermogravimetric analysis indicated that the grafting amount of CSPE was 4.68 wt%. Grafting CSPE onto silica surface significantly improved the dispersion of CSPE‐g‐SiO₂ nanoparticles in CSPE matrix and the interfacial interaction. Therefore, the mechanical, thermal stability, damping capacity, and rheology properties of CSPE/CSPE‐g‐SiO₂ nanocomposites were improved. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Modification of polyethylene–octene elastomer by silica through a sol–gel process

In this study, tetraethoxysilane (TEOS) and a metallocene polyethylene–octene elastomer (POE) were chosen as the ceramic precursor and the continuous phase, respectively, for the preparation of new hybrids by an in situ sol–gel process. To obtain a better hybrid, a maleic anhydride‐grafted polyethylene–octene elastomer (POE‐g‐MAH), used as the continuous phase, was also investigated. Characterizations of POE‐g‐MAH/SiO₂ and POE/SiO₂ hybrids were performed by Fourier transform infrared (FTIR) and ²⁹Si solid‐state nuclear magnetic resonance (NMR) spectrometers, a differential scanning calorimeter (DSC), a thermogravimetry analyzer, and an Instron mechanical tester. The results showed that the POE‐g‐MAH/SiO₂ hybrid could improve the properties of the POE/SiO₂ hybrid because the interfacial force between the polymer matrix and the silica network was changed from hydrogen bonds into covalent Si? O? C bonds through dehydration of hydroxy groups in POE‐g‐MAH with residual silanol groups in the silica network. The existence of covalent Si? O? C bonds was proved by FTIR spectra. For the POE/SiO₂ and POE‐g‐MAH/SiO₂ hybrids, maximum values of the tensile strength and the glass transition temperature were found at 9 wt % SiO₂ since a limited content of silica might be linked with the polymer chains through the covalent bond. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 966–972, 2003