Coupling Agent (coupling + agent)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Coupling Agent

  • silane coupling agent

  • Selected Abstracts

    Fluorous 2,4-Dichloro-1,3,5-triazine (F-DCT) as an Amide Coupling Agent

    Wei Zhang
    Abstract 1H,1H,2H,2H,3H,3H -perfluoroundecanol displaced 2,4-dichloro-1,3,5-triazine 5 is synthesized and used as a condensation agent for amide synthesis. Two active sites on the triazine ring lead to formation of two equivalents of amidation products. The purification of reaction mixtures is accomplished by plate-to-plate fluorous solid-phase extraction. [source]

    The Effect of Silane Coupling Agents on the Viscoelastic Properties of Rubber Biocomposites

    Maya Jacob
    Abstract Summary: This paper deals with the dynamic mechanical study of sisal/oil palm hybrid fiber reinforced natural rubber composites (at frequency 1 Hz) with reference to the role of silane coupling agents. Composites were prepared using sisal and oil palm fibers subjected to chemical modifications with different types of silane coupling agents. The silanes used were Silane F8261 [1,1,2,2-perfluorooctyl triethoxy silane], Silane A1100 [, -aminopropyltriethoxy silane] and Silane A151 [vinyl triethoxy silane]. It was observed that for treated composites, storage modulus and loss modulus increased while the damping property was found to decrease. Maximum E' was exhibited by the composite prepared from fibers treated with silane F8261 and minimum by composites containing fibers treated with silane A151. This was attributed to the reduced moisture absorbing capacity of chemically modified fibers leading to improved wetting. This in turn produced a strong interfacial interface giving rise to a much stiffer composite with higher modulus. Surface characterization of treated and untreated sisal fibers by XPS showed the presence of numerous elements on the surface of the fiber. Scanning electron micrographs of tensile fracture surfaces of treated and untreated composites demonstrated better fiber,matrix bonding for the treated composites. Scheme of interaction of silanes with cellulosic fibers. [source]

    Microwave Irradiated High-Speed Solution Synthesis of Peptide Acids Employing Fmoc-Amino Acid Pentafluorophenyl Esters as Coupling Agents.

    CHEMINFORM, Issue 10 2006
    Vommina V. Suresh Babu
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    A Novel Method for the Assessment of Methyl Parathion by Using Coupling Agents in Environmental and Commercial Samples

    Padmarajaiah Nagaraja
    Abstract A sensitive and rapid spectrophotometric method for the determination of reduced methyl parathion (=O,O -dimethyl O -(4-nitrophenyl) phosphorothioate) is described. The method is based on the interaction of diazotized reduced methyl parathion with 8-hydroxyquinoline (=quinolin-8-ol; 8-HQ) and 3-aminophenol (3-AP) as new coupling agents. Absorbances of the resulting chromophores are measured at 430 and 440,nm, respectively, and colored products were stable for at least 2 days. Beer's law is obeyed over the methyl parathion concentration range 0.2,5.5,,g ml,1 for 8-HQ and 0.5,6.0,,g ml,1 for 3-AP. From the data, it was confirmed that the two coupling agents can be effectively applied for the determination of methyl parathion in environmental and commercial samples. [source]

    Influence of Coupling Agents on Melt Flow Behavior of Natural Fiber Composites

    Velichko Hristov
    Abstract The influence of coupling agents on the melt rheological properties of natural fiber composites has been investigated in this work using capillary and rotational rheometers. Scanning electron microscopy was also employed to supplement the rheological data. It was found that molecular weight and molecular weight distribution of the polymer matrix and coupling agent characteristics influence the filler wetting and the melt flow properties of the filled composites. Generally, low molecular weight and narrow molecular weight distribution polyethylene matrix provides relatively larger increase of the viscosity of the composites. Coupling agents tend to increase the resistance to shearing, but wall slip effects may interfere with the measured values, especially at very high filler loadings. Entrance pressure loss in capillaries is also influenced by polymer matrix and coupling agent used. [source]

    BaTiO3,Epoxy Composites for Electronic Applications

    Leandro Ramajo
    A brief review related with dielectric properties of BaTiO3/epoxy composites is presented. The composites were obtained using the dipping technique. To facilitate the mixing and modify the filler surface, a solvent and a surface coupling agent were used. Intermediate and low concentrations of solvent and silane improved microstructure and dielectric properties of the composite material, whereas higher concentrations led to composites of poor quality. Finally, a model using finite elements was used, in order to predict the composite permittivity in relation to the percentage of filler. Model results were compared with the effective medium theory and experimental results. [source]

    Thermoplastic silicone elastomer lubricant in extrusion of polypropylene wood flour composites

    Velichko Hristov
    Abstract A possibility of using a thermoplastic silicone elastomer (TPSE) for reduction of surface defects in the extrusion of wood-filled metallocene polypropylene (mPP) has been investigated in this work. A capillary rheometer and a single-screw extruder have been utilized to study the effect of the additive on the extrudate distortions. Maleated syndiotactic metallocene polypropylene was also used as an adhesion promoter in mPP/wood flour composites. At loadings of 50 wt% wood flour in the mPP, the extrudates come out of the die with significant tearing and surface roughness. The surface rupture mechanism is similar to that of sharkskin in neat polymers; however, the defect is much more exaggerated in the case of wood fiber-filled composites. It was found that TPSE at low concentrations (1 wt%) was able to reduce or even completely eliminate extrudate surface tearing. Increasing the extrusion speed yielded better results. Addition of a coupling agent also provides improvement in the extrudate appearance. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:100,108, 2007; Published online in Wiley InterScience ( DOI 10.1002/adv.20090 [source]

    Development of an extrusion system for producing fine-celled HDPE/wood-fiber composite foams using CO2 as a blowing agent

    H. Zhang
    Abstract This paper presents an innovative design of a tandem extrusion system for fine-celled foaming of plastic/wood-fiber composites using a physical blowing agent (PBA). The plastic/wood-fiber composites utilize wood-fibers (WF) as a reinforcing filler in the plastic matrix and are known to be advantageous over the neat plastics in terms of the materials cost and some improved mechanical properties such as stiffness and strength. However, these improvements are usually accompanied by sacrifices in the ductility and impact resistance. These shortcomings can be reduced by inducing fine-celled or microcellular foaming in these composites, thereby creating a new class of materials with unique properties. An innovative tandem extrusion system with continuous on-line moisture removal and PBA injection was successfully developed. The foamed composites, produced on the tandem extrusion system, were compared with those produced on a single extruder system, and demonstrated significant improvement in cell morphology, resulting from uniform mixing and effective moisture removal. The effects of WF and coupling agent (CA) on the cell morphology were studied. An increase in the WF content had an adverse affect. The cell morphology and foam structures were improved when an appropriate CA was added. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 263,276, 2004; Published online in Wiley InterScience ( DOI 10.1002/adv.20016 [source]

    Crystallization and melting behavior of HDPE in HDPE/teak wood flour composites and their correlation with mechanical properties

    Kamini Sewda
    Abstract The nonisothermal crystallization behavior and melting characteristics of high-density polyethylene (HDPE) in HDPE/teak wood flour (TWF) composites have been studied by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) methods. Composite formulations of HDPE/TWF were prepared by varying the volume fraction (,f) of TWF (filler) from 0 to 0.32. Various crystallization parameters evaluated from the DSC exotherms were used to study the nonisothermal crystallization behavior. The melting temperature (Tm) and crystallization temperature (Tp) of the composites were slightly higher than those of the neat HDPE. The enthalpy of melting and crystallization (%) decrease with increase in the filler content. Because the nonpolar polymer HDPE and polar TWF are incompatible, to enhance the phase interaction maleic anhydride grafted HDPE (HDPE-g-MAH) was used as a coupling agent. A shift in the crystallization and melting peak temperatures toward the higher temperature side and broadening of the crystallization peak (increased crystallite size distribution) were observed whereas crystallinity of HDPE declines with increase in ,f in both DSC and WAXD. Linear correlations were obtained between crystallization parameters and tensile and impact strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Comparison of the effects of polyethylenimine and maleated polypropylene coupling agents on the properties of cellulose-reinforced polypropylene composites

    C. González-Sánchez
    Abstract The desire to improve the properties of cellulose-reinforced composites while producing them by methods as similar as possible to those used on an industrial scale is one of the driving forces in this field of research. In this work, extensive research for determining the mechanical, thermal, rheological, and physical properties of novel cellulose-reinforced polypropylene composites containing a polyethylenimine (PEI) coupling agent was conducted. A comparison of their properties with those of reference composites without any coupling agent or containing a maleated polypropylene (MAPP) coupling agent was also carried out. The presence of the PEI coupling agent mainly gave rise to a substantial increase in the tensile and flexural strengths and elongations as well as the impact strength, heat deflection temperature (HDT), melt volume flow index, and water absorption of PEI-containing composites in comparison with composites without any coupling agent added. However, the increases achieved in the tensile and flexural composite strengths and HDT were lower than those achieved with the MAPP coupling agent mainly for composites containing 50 wt % cellulose fibers. On the other hand, PEI-containing composites exhibited, in most cases, larger elongations and energies required to break in tensile tests as well as larger impact strengths, melt volume flow indices, and water absorption percentages than MAPP-containing composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Poly(lactic acid)-based biocomposites reinforced with kenaf fibers

    Maurizio Avella
    Abstract Biodegradable thermoplastic-based composites reinforced with kenaf fibers were prepared and characterized. Poly(lactic acid) (PLA) was selected as polymeric matrix. To improve PLA/fibers adhesion, low amount of a proper reactive coupling agent, obtained by grafting maleic anhydride onto PLA, was added during matrix/fibers melt mixing. Compared with uncompatibilized composites, this compatibilization strategy induces a strong interfacial adhesion and a pronounced improvement of the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Measurement of the condensation temperature of nanosilica powder organically modified by a silane coupling agent and its effect evaluation

    Xiao Liu
    Abstract The proper condensation temperatures of nanosilica powder modified by silane coupling agents such as 3-methacryloxypropyl trimethoxy silane (MEMO), [3-(2-aminoethyl)aminopropyl] trimethoxy silane (AMMO), and bis[3-(triethoxysilyl)propyl] disulfide (TESPD) were measured with Fourier transform infrared. Moreover, the structure and properties of solution-polymerized styrene,butadiene rubber (SSBR) filled with nanosilica powder that was organically modified by the three silane coupling agents at different temperatures were investigated. The results showed that the proper condensation temperatures of nanosilica powder modified by MEMO, AMMO, and TESPD were about 80, 80, and 100°C, respectively. Compared with SSBR filled with silica powder, SSBR filled with silica powder modified by a silane coupling agent exhibited not only better filler-dispersion and mechanical properties but also lower internal friction loss in a selected range of strains. Furthermore, when the organic modification was carried out at the proper condensation temperature, the improvement of the modification effect became more obvious. Among these silane coupling agents, AMMO presented the most remarkable modification effect for nanosilica. The mechanism of modification for silica powder and its enhancement of the properties of SSBR were examined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Effect of silane KH-550 to polypropylene/brucite composite

    Zhiling Ma
    Abstract The effect of the KH-550 type silane coupling agent on the properties of polypropylene (PP)/brucite (BC) composite was studied. X-ray diffraction, scanning electron microscope, and polarization optical microscope indicated that morphology structure of PP changed with the addition of KH-550, which activated the heterogeneous nucleation centers on BC surface, which made the distribution of the spherulite diameter become narrow and uniform, and improved the dispersibility of BC in the matrix. Therefore, KH-550 enhanced the interfacial adhesion of matrix-filler and improved the compatibility of the PP/BC composite, when KH-550's content was 2.9% the tensile strength and impact strength increased approximately by 90% and by 30%, respectively than PP/BC. Flow tests and IR proved that some reactions took place between BC and KH-550. All the investigations showed KH-550 was a proper coupling agent in the PP/BC composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Mechanical and morphological properties of organic,inorganic, hybrid, clay-filled, and cyanate ester/siloxane toughened epoxy nanocomposites

    S. Nagendiran
    Abstract Organic,inorganic hybrids involving cyanate ester and hydroxyl-terminated polydimethylsiloxane (HTPDMS) modified diglycidyl ether of bisphenol A (DGEBA; epoxy resin) filled with organomodified clay [montmorillonite (MMT)] nanocomposites were prepared via in situ polymerization and compared with unfilled-clay macrocomposites. The epoxy-organomodified MMT clay nanocomposites were prepared by the homogeneous dispersion of various percentages (1,5%), and the resulting homogeneous epoxy/clay hybrids were modified with 10% HTPDMS and ,-aminopropyltriethoxysilane as a coupling agent in the presence of a tin catalyst. The siliconized epoxy/clay prepolymer was further modified separately with 10% of three different types of cyanate esters, namely, 4,4,-dicyanato-2,2,-diphenylpropane, 1,1,-bis(3-methyl-4-cyanatophenyl) cyclohexane, and 1,3-dicyanato benzene, and cured with diaminodiphenylmethane as a curing agent. The reactions during the curing process between the epoxy, siloxane, and cyanate were confirmed by Fourier transform infrared analysis. The results of dynamic mechanical analysis showed that the glass-transition temperatures of the clay-filled hybrid epoxy systems were lower than that of neat epoxy. The data obtained from mechanical studies implied that there was a significant improvement in the strength and modulus by the nanoscale reinforcement of organomodified MMT clay with the matrix resin. The morphologies of the siloxane-containing, hybrid epoxy/clay systems showed heterogeneous character due to the partial incompatibility of HTPDMS. The exfoliation of the organoclay was ascertained from X-ray diffraction patterns. The increase in the percentage of organomodified MMT clay up to 5 wt % led to a significant improvement in the mechanical properties and an insignificant decrease in the glass-transition temperature versus the unfilled-clay systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    An alternative approach to the modification of talc for the fabrication of polypropylene/talc composites

    Tao Wang
    Abstract We report an alternative method to modify talc for use in the fabrication of composites of polypropylene (PP) and talc. Grinding pulverization is employed to prepare talc fillers (referred to hereafter as p -talc). The properties of composites made with p -talc compare favorably with composites made with pulverized talc that has been further treated with a silane coupling agent (referred to as s -talc). The morphology of PP/p -talc composites illustrates particle orientation and a uniform dispersion of pulverized talc in the PP matrix. Modulated DSC analysis shows the ability of p -talc and s -talc to nucleate PP crystallization. The mechanical properties (i.e., the dynamic modulus, tensile strength, and impact resistance) of the PP/p -talc composites are very similar to PP/s -talc composites. The modification of talc by grinding is thus a highly effective alternative method to prepare PP/talc composites that does not require chemical treatment of the talc. The pulverization method is simpler and less expensive in comparison to silane treatment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Properties of amylopectin/montmorillonite composite films containing a coupling agent

    D. Nordqvist
    Abstract The addition of clay to polymers has the combined effects of enhancing both the strength/stiffness and the barrier properties. This investigation presents a novel approach to further enhance the strength/stiffness of cast plasticized amylopectin (AP)/Na+ -montmorillonite clay films using a water-soluble coupling agent, poly[(isobutylene- alt -maleic acid, ammonium salt)- co -(isobutylene- alt -maleic anhydride)], between the filler and the matrix. The addition of clay increased the strength and stiffness of the film and the addition of 0.4 parts of a coupling agent per 1 part clay further increased these properties. The trends were the same after each treatment, and there were always significant differences in stiffness and strength between the films without clay and with clay with 0.4 parts of the coupling agent. The increase in stiffness/strength in the presence of a small amount of the coupling agent suggested that it had a bridging effect, presumably through strong secondary bonds to the clay and to the matrix. Infrared spectroscopy and moisture swelling experiments indicated that ester bonds were formed between the coupling agent and AP. X-ray spectroscopy and transmission electron microscopy revealed that the clay-particle/polymer structure was qualitatively independent of the presence of the coupling agent showing a mixture of intercalated clay stacks and exfoliated platelets. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4160,4167, 2007 [source]

    Fabrication and properties of nano-ZnO/glass-fiber-reinforced polypropylene composites

    Yi-Hua Cui
    Polypropylene (PP) is widely used in many fields, such as automobiles, medical devices, office equipment, pipe, and architecture. However, its high brittle transformation temperature, low mechanical strength, dyeing properties, antistatic properties, and poor impact resistance, considerably limit its further applications. Nano-ZnO treated by KH550 coupling agent and glass fibers (GFs) were introduced in order to improve the mechanical performance and flowability of PP in this research. The crystallization behavior and microstructure of nano-ZnO/GFs/PP hybrid composites were analyzed by differential scanning calorimetry, transmission electron microscopy, and scanning electron microscopy. The effect of crystallization behavior on the mechanical properties of the nanocomposites was investigated and analyzed. The results indicated that nano-ZnO surface-coupled by KH550 could be uniformly dispersed in the PP matrix. The incorporation of nano-ZnO and GFs resulted in increases of the crystallization temperature and crystallization rate of PP and a decrease of the crystallization degree. The introduction of nano-ZnO and GFs also enhanced the tensile strength and impact toughness of the hybrid composites and improved their fluidity. Composites containing 2% of nano-ZnO and 40% of GFs possessed the optimum mechanical properties. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source]

    Synthesis and Optical Properties of Soluble Polyimide/Titania Hybrid Thin Films

    Chih-Ming Chang
    Abstract Summary: In this study high-refractive-index polyimide/titania hybrid optical thin films were successfully prepared using a sol-gel process combined with spin coating and multistep baking. The hybrid thin films were prepared from a soluble polyimide, a coupling agent, and a titania precursor. Transparent hybrid thin films can be obtained at TiO2 content as high as 40 wt.-%. The FE-SEM results suggest that the TiO2 particles in the hybrid thin films have diameters in the nanometer range. The thermal decomposition temperatures of the prepared hybrid materials are above those of the respective polyimide except for the highest TiO2 content hybrids. The refractive indices at 633 nm of the prepared hybrid thin films increase linearly from 1.66 to 1.82 with increasing TiO2 content. The excellent optical transparency, thermal stability, and tunable refractive index provide the potentials of the polyimide/titania hybrid thin films in optical applications. [source]

    Influence of Reactice Processing on the Properties of PP/Glass Fiber Composites Compatibilized with Silane

    Afonso H. O. Felix
    Abstract Summary: Composites of PP reinforced with 20 wt.-% of short glass fibers were prepared by extrusion using VTES as a coupling agent. The addition of VTES was performed via in-situ functionalization of PP and by a two-step process in which PP was functionalized before the composite preparation. The obtained samples were characterized using rheometry, mechanical tests and microscopy. Both processes allowed the fiber/matrix interaction to increase. It was found that the VTES content affected the viscosity of the system by means of three different mechanisms: reduction of , -scission reactions, decrease of fiber sliding and plasticizing effect on the matrix. Whereas the first two mechanisms increased the viscosity of the final composite after unreacted VTES removal, the third one reduced the viscosity during the process and contributed to fiber-length preservation. The effects of VTES and peroxide contents on the Young's modulus were closely related to their effects on the final fiber length, indicating the effectiveness of using VTES as a coupling agent. Comparison between in-situ functionalization and the two-step process with prefunctionalization showed that in-situ functionalization led to a lower degree of chain breakage, even when it was performed in the presence of peroxide. Scanning electron micrographs of PP/glass fiber composite prepared without coupling agent. [source]

    Effect of High-Energy Vibromilling on Interfacial Interaction and Mechanical Properties of PVC/Nano-CaCO3 Composites

    Manhong Tian
    Abstract Summary: The effects of interfacial interaction between nano-CaCO3 and PVC on mechanical properties and morphology of PVC/nano-CaCO3 composites were studied. Nano-CaCO3 was treated with vibromilling in the presence of PVC and coupling agents. The mechanical properties of PVC/treated nano-CaCO3 are remarkably improved. Transmission electron microscopy results revealed that vibromilled nano-CaCO3 particles are well dispersed in PVC matrix with good homogeneity and well adhered to PVC matrix. Molau test indicated that chemical reaction between newly formed surface of nano-CaCO3 and PVC or coupling agent took place. Theoretical calculation results show that the interfacial interaction between PVC and nano-CaCO3 are substantially improved through vibromilling treatment of nano-CaCO3 in the presence of PVC and coupling agent. Molau test results of the samples in THF. [source]

    Telechelic Polyisobutenes with Asymmetrical Reactivity

    Arno Lange
    Abstract 3-Chlorocyclopentene-(1) has been used as initiator in the quasiliving cationic polymerization of isobutene. Polyisobutenes in the molecular weight range Mw = 300 - 60000 Dalton with a molecular weight distribution MWD between 1.17 and 1.34 have been synthesized. The linear polymer was selectively hydrosilated on one or both ends. With a furan coupling agent, the PIB (polyisobutene) was dimerized, yielding polymers with a cyclopentene head- and tail group. [source]

    Antimicrobial activity of glucose oxidase-immobilized plasma-activated polypropylene films

    Jari Vartiainen
    Abstract Antimicrobial enzyme, glucose oxidase (GOX), was covalently immobilized onto amino- and carboxyl-plasma-activated biorientated polypropylene films (BOPP) via glutaraldehyde and carbodiimide chemistries. N2 -plasma + NH3 and N2 -plasma + CO2 treatments were utilized to create amino (1.1,nmol/cm2) and carboxyl (0.9,nmol/cm2) groups densities onto the surface of BOPP films. GOX-immobilized onto amino-activated BOPP films using 2.5% glutaraldehyde produced higher enzymatic activities than GOX-immobilized by 0.4% carbodiimide. Further immobilizations were carried out with glutaraldehyde as the coupling agent at temperatures of 4,75°C at pH 5.6 and 7.2. 10,s treatment was sufficient to immobilize GOX at high temperatures in both pH conditions, producing enzymatically active films which remained active over 30 days of storage. GOX covalently immobilized onto BOPP films completely inhibited the growth of Escherichia coli and substantially inhibited the growth of Bacillus subtilis; thus, they may have great potential to be exploited in various antimicrobial packaging film applications. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Influence of interfacial adhesion on the structural and mechanical behavior of PP-banana/glass hybrid composites

    POLYMER COMPOSITES, Issue 7 2010
    Sanjay K. Nayak
    Hybrid composites of polypropylene (PP), reinforced with short banana and glass fibers were fabricated using Haake torque rheocord followed by compression molding with and without the presence maleic anhydride grafted polypropylene (MAPP) as a coupling agent. Incorporation of both fibers into PP matrix resulted in increase of tensile strength, flexural strength, and impact strength upto 30 wt% with an optimum strength observed at 2 wt% MAPP treated 15 wt% banana and 15 wt% glass fiber. The rate of water absorption for the hybrid composites was decreased due to the presence of glass fiber and coupling agent. The effect of fiber loading in presence of coupling agent on the dynamic mechanical properties has been analyzed to investigate the interfacial properties. An increase in storage modulus (E,) of the treated-composite indicates higher stiffness. The loss tangent (tan ,) spectra confirms a strong influence of fiber loading and coupling agent concentration on the , and , relaxation process of PP. The nature of fiber matrix adhesion was examined through scanning electron microscopy (SEM) of the tensile fractured specimen. Thermal measurements were carried out through differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA), indicated an increase in the crystallization temperature and thermal stability of PP with the incorporation of MAPP-treated banana and glass fiber. POLYM. COMPOS., 31:1247,1257, 2010. © 2009 Society of Plastics Engineers [source]

    Preparation, morphology, and adhesive and mechanical properties of ultrahigh-molecular-weight polyethylene/SiO2 nanocomposite fibers

    POLYMER COMPOSITES, Issue 4 2010
    Yi Zhang
    A simple treatment approach has been performed to achieve enhanced surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) fibers by incorporation of nano-silicon dioxide (SiO2) in the presence of silane coupling agent during gel-spinning process. The SiO2 -treated UHMWPE (UHMWPE/SiO2) nanocomposite fibers with different nano-SiO2 compositions were characterized with Fourier transform infrared spectra, scanning electron microscopy, and wide-angle X-ray diffraction, and their interfacial adhesion and mechanical properties were also investigated. The nano-SiO2 can be trapped on the surface of the fibers to form rough surface for UHMWPE/SiO2 fibers, and diffused into the inner of fibers to induce the lower crystal sizes and higher crystallinity of polyethylene in UHMWPE/SiO2 fibers. The resulting UHMWPE/SiO2 fibers therefore exhibit a dramatic enhancement in the adhesive properties because of the combination of rougher surface compared with those of UHMWPE fiber and polar groups absorbed on the surface of fibers. The mechanical properties of UHMWPE/SiO2 nanocomposite fibers are enhanced simultaneously because of the influence of nano-SiO2 on the structure of UHMWPE crystalline regions and fibrils. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

    Preparation, characterization, and thermal stability of novel PMMA/expandable graphite halogen-free flame retardant composites

    POLYMER COMPOSITES, Issue 1 2010
    Chia-Hsun Chen
    In this investigation, expandable graphite was functionalized using a coupling agent to produce covalent bonds between the organic and inorganic phases, enhancing the thermal stability of the composites. The modified expandable graphite had an OEt function group that reacted with methyl methacrylate- co -3-(trimethoxysilyl)propyl methacrylate. Fourier transform-infrared spectrometry and X-ray photoelectron spectra were adopted to characterize the grafting reaction between vinyltriethoxysilane and expandable graphite. It is affirmed that VTES has reacted with expandable graphite. The results of thermogravimetric analysis and thermogravimetric difference (TG,) reveal that functionalized expandable graphite can improve the thermal stability of composites. Scanning electron microscope was utilized to observe the morphology of the composites, and the behavior of expansion was discussed after the materials were burned. These results of X-ray photoelectron spectra for char confirm that expandable graphite improves the degree of accumulation of char and that of the antioxidation of the composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

    An investigation on the mechanical and dynamic rheological properties of single and hybrid filler/polypropylene composites based on talc and calcium carbonate

    POLYMER COMPOSITES, Issue 12 2009
    Hamed Azizi
    Some results of experiments on the mechanical and rheological properties of mineral filled polypropylene were presented. Single filler and hybrid filler composites of talc and calcium carbonate (CaCO3) were prepared in a co-rotating twin-screw extruder. The effect of filler type, filler content, and coupling agent on the mechanical and rheological properties of the polypropylene were studied. The coupling agent was maleic anhydride-grafted polypropylene (PP- g -MA). It was found that the mechanical properties are affected by filler type, filler concentration, and the interaction between filler and matrix. The tensile strength of the composite is more affected by the talc while the impact strength is influenced mostly by CaCO3 content. The elongation at break of PP/CaCO3 composites was higher than that of PP/talc composites. The incorporation of coupling agent into PP/mineral filler composites increased the mechanical properties. Rheological properties indicated that the complex viscosity and storage modulus of talc filled samples were higher than those of calcium carbonate filled samples while the tan , was lower. The rheological properties of hybrid-filler filled sample were more affected by the talc than calcium carbonate. The PP- g -MA increased the complex viscosity and storage modulus of both single and hybrid composites. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers [source]

    Characterization and properties of activated nanosilica/polypropylene composites with coupling agents

    POLYMER COMPOSITES, Issue 11 2009
    Ong Hui Lin
    In this work, nanosilica/polypropylene composites containing 1 wt% of silica nanoparticles were prepared by melt mixing in a Thermo Haake internal mixer. Prior compounding, nanosilica was subjected to surface activation using sodium hydroxide (NaOH) solution. The effectiveness of the activation process was evaluated by measuring the amount of hydroxyl groups (OH) on the surface of nanosilica via titration method and supported by FTIR analysis. Two coupling agents namely 3-aminopropyl triethoxysilane (APTES) and neopentyl (diallyl)oxy, tri(dioctyl) phosphate titanate (Lica 12) were used for surface treatment after activation process. The mechanical properties of polypropylene matrix reinforced with silica nanoparticles were determined by tensile and impact test. Hydroxyl groups on the nanosilica surface played an important role in enhancing the treatment with silane coupling agents. To increase the amount of hydroxyl groups on the nanosilica surface, the optimum concentration of NaOH is 1 mol%. Tensile strength, tensile modulus, and impact strength of nanosilica/PP composites improved with activation process. As the coupling agent is concerned, APTES coupling agent is more pronounced in enhancing the mechanical properties of the composites when compared with Lica 12 coupling agent. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

    Rheological behavior of LDPE/CaCO3 blends containing EAA

    POLYMER COMPOSITES, Issue 9 2009
    Aiqin Dong
    Calcium carbonate (CaCO3) filler particles were surface treated with organic titanate (TTS), a coupling agent. The composites were prepared by blending low-density polyethylene (LDPE) with the surface-modified fillers at various weight ratios. Ethylene-acrylic acid copolymer (EAA) was added to improve the adhesion of LDPE to fillers. A capillary rheometer was used to evaluate rheological properties of the LDPE/CaCO3/EAA blends. The blends were shown to be pseudoplastic with shear thinning behavior. When CaCO3 was modified by TTS (<2 wt%), the viscosity of the blends decreased quickly, and, addition of a small amount of EAA (<6 wt%) could also decrease the viscosity of the blends. The thermal behavior of these materials is evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of a small amount of EAA and TTS enhances the stabilization of the blends, which could be explained by the "ball belling" action. The effects of temperature, TTS content, CaCO3 granule size, and content on the rheological property were also studied. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

    Improving the properties of LDPE/glass fiber composites with silanized-LDPE

    POLYMER COMPOSITES, Issue 7 2009
    Felipe W. Fabris
    Low density polyethylene (LDPE) is a widely used thermoplastic. The dispersion of inorganic fillers in thermoplastic matrices such as polyethylene has been largely employed to improve some of its properties. However, interaction between both components is a major issue so the presence of a coupling agent is usually necessary to increase the interaction among the phases. In this study, LDPE chemically modified with vinyltriethoxysilane (VTES) was used as a coupling agent in glass fiber-reinforced LDPE. The composites were prepared in a mixing chamber and subsequently analyzed by tensile tests, rotational rheometry, and scanning electron microscopy (SEM). The mechanical properties were significantly increased by the use of small amounts of the coupling agent. Moreover, the rheological behavior and the SEM micrographs showed higher interaction between the matrix and the reinforcing phase in the composites containing LDPE modified with VTES, confirming the suitability of using this coupling agent in these systems. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

    Interfacial adhesion and molecular diffusion in melt lamination of wood sawdust/ebonite NR and EPDM

    POLYMER COMPOSITES, Issue 3 2009
    W. Yamsaengsung
    Adhesion mechanisms and peel strengths of wood/ebonite NR-EPDM laminates were investigated. Three different chemical coupling agents: namely; N-(, aminoethyl)-,-aminopropyl-triethoxysilane (AAS), 3-methacryloxypropyl trimethoxysilane (ACS), and Bis-(3-triethoxylpropyl) tetrasulfan (Si69) were introduced into the wood/NR composites to enhance an interaction between wood sawdust (SD) particles and NR molecules, and to improve the adhesion strength between the SD/NR and EPDM layers. The quantitative evidences were given to explain the changes in the adhesion or peel strengths of the SD/NR-EPDM laminates through scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). The experimental results indicated that the suitable cure time and cure temperature for SD/NR-EPDM melt-laminates were the tc90 of SD/NR composites and 140°C, respectively. The Si69 coupling agent was found to be the most effective coupling agent as compared with AAS and ACS coupling agents. The Si69 of 0.5 wt% was recommended for the optimizations of the tensile modulus of the SD/NR composites and the peel strength of the SD/NR-EPDM laminates. The diffusion level between the SD/NR and EPDM layers could be quantitatively substantiated by determining the sulfur content transfer from the SD/NR layer to the EPDM layer. The diffusion and entanglement of molecular chains from the SD/NR to the EPDM layer initiated the co-crosslinking reaction which played an important role on the changes in the interfacial strength in the SD/NR-EPDM melt-laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]