The influence of silane treatment on nylon 6/nano‐SiO2 in situ polymerization

Silane treatment has been applied to the preparation of nylon 6/nano‐SiO₂ composites through in situ polymerization. The influence of such treatment on the reactivity of silica, polymerization of nylon 6, and the mechanical properties of the achieved composites has been studied. Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA) of silicas isolated from the composites have shown that the conversion of surface silanol groups to amino and epoxy groups did not cause a significant change in the reactivity of silica and that the percentage of silica surface grafting was around 15% for all treated and untreated silicas. End group analysis has shown that the presence of silica (pretreated or not) in the composite system resulted in the decrease of the average molecular weight of the polymer matrix. However, dynamic mechanical analysis and mechanical tests revealed that treating silica with silane improved the strength and toughness of the composite materials, while untreated silica improved their strength at the expense of toughness. This can be attributed to the existence of the flexible interlayer introduced by silane treatment. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 827–834, 2002; DOI 10.1002/app.10349     

MC尼龙6/纳米SiO2复合材料的合成

用原位聚合法制备MC尼龙6／纳米SiO2复合材料。当纳米SiO2的加入量为1％时,力学综合性能最优。与纯MC尼龙相比,拉伸强度提高21％,弯曲模量提高40．3％,简支梁冲击强度提高69．1％,断裂伸长率降低43％。随着纳米SiO2含量的增加,复合材料的力学性能呈现减小趋势。采用SEM、XRD对产物进行了表征,表明采用修饰后的纳米SiO2加入到产物中,粒子分布均匀,粒径分布窄,粒子的粒径在30nm左右。随着纳米SiO2加入量的增加,MC尼龙6／纳米SiO2复合材料的结晶度下降。     

Preparation and properties of nylon 6/carboxylic silica nanocomposites via in situ polymerization

Nylon 6/carboxylic acid‐functionalized silica nanoparticles (SiO₂‐COOH) nanocomposites were prepared by in situ polymerization of caprolactam in the presence of SiO₂‐COOH. The aim of this work was to study the effect of carboxylic silica on the properties of the nylon 6 through the interfacial interactions between the SiO₂‐COOH nanoparticles and the nylon 6 matrix. For comparison, pure nylon 6, nylon 6/SiO₂ (unmodified) and nylon 6/amino‐functionalized SiO₂ (SiO₂‐NH₂) were also prepared via the same method. Fourier transform infrared spectrometer (FTIR) spectroscopy was used to evaluate the structure of SiO₂‐COOH and nylon 6/SiO₂‐COOH. The results from thermal gravimetric analysis (TGA) indicated that decomposition temperatures of nylon 6/SiO₂‐COOH nanocomposites at the 5 wt % of the total weight loss were higher than the pure nylon 6. Differential scanning calorimeter (DSC) studies showed that the melting point (T_m) and degree of crystallinity (X_c) of nylon 6/SiO₂‐COOH were lower than the pure nylon 6. Mechanical properties results of the nanocomposites showed that nylon 6 with incorporation of SiO₂‐COOH had better mechanical properties than that of pure nylon 6, nylon 6/SiO₂, and nylon 6/SiO₂‐NH₂. The morphology of SiO₂, SiO₂‐NH₂, and SiO₂‐COOH nanoparticles in nylon 6 matrix was observed using SEM measurements. The results revealed that the dispersion of SiO₂‐COOH nanoparticles in nylon 6 matrix was better than SiO₂ and SiO₂‐NH₂ nanoparticles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of conducting polyaniline/TiO2 composite nanofibres by one‐step in situ polymerization method

Conducting polyaniline (PANI)/titanium dioxide (TiO₂) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO₂ particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO₂ composite nanofibres was also discussed. This composite contained ～ 65% conducting PANI by mass, with a conductivity of 1.42 S cm^?1 at 25°C, and the conductivity of control PANI was 2.4 S cm^?1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation of conductive polyaniline/nylon‐6 composite films by polymerization of aniline in nylon‐6 matrix

Polyaniline (PANI)/Nylon‐6 composite films were prepared by oxidative polymerization of aniline (ANI) inside host Nylon‐6 film. Such a composite has the desired electro‐active and mechanical properties to serve as a self‐standing functional unit. Comparative studies on sorption of ANI by Nylon‐6 matrix from various ANI containing media were conducted revealing superior ANI uptake from neutral ANI solution in water. ANI content was measured to be as high as 12%. Spectroscopic measurements showed that hydrogen bonding seemed to play important role in ANI sorption by Nylon‐6 matrix. Polymerization was monitored using atomic force microscopy and conductivity measurements. The morphology studies showed the appearance of PANI nanodomains on Nylon‐6 surface in the early stages of the polymerization. Eventually the domains coalesced during polymerization forming a continuous PANI layer. The conductivity measurements confirmed the change of the morphology from isolated islands to continuous conducting surface by drastic increase in conductivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Friction and wear studies on nylon‐6/SiO2 nanocomposites

Composites of nanometer‐sized silica (SiO₂) filler incorporated in nylon‐6 polymer were prepared by compression molding. Their friction and wear properties were investigated on a pin on disk tribometer by running a flat pin of steel against a composite disc. The morphologies of the composites as well as of the wear track were observed by scanning electron microscopy (SEM). The addition of 2 wt % SiO₂ resulted in a friction reduction (μ) from 0.5 to 0.18 when compared with neat nylon‐6. This low silica loading led to a reduction in wear rate by a factor of 140, whereas the influence of higher silica loadings was less pronounced. The smooth morphology obtained after the wear test indicated the negligible contribution to friction of the pin to the nanocomposite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1855–1862, 2004     

Effect of in situ surface‐modified nano‐SiO2 on the thermal and mechanical properties and crystallization behavior of nylon 1010

Nylon 1010 composites filled with two types of surface‐modified SiO₂ nanoparticles (RNS and DNS) were prepared by melt blending. The mechanical properties of the composites were evaluated. The influences of the surface‐modified nano‐SiO₂ on the thermal stability, crystallization behavior, and microstructure of nylon 1010 were investigated by thermogravimetric analysis, differential scanning calorimetry (DSC), X‐ray diffraction, and transmission electron microscopy. And the interfacial interactions between the fillers and polymer matrix were examined using a Fourier transformation infrared spectrometer. It was found that the addition of the surface‐modified nano‐SiO₂ had distinct influences on the thermal stability, mechanical properties, and crystallization behavior of nylon 1010. RNS and DNS as the fillers had different effects on the mechanical properties of nylon 1010. The composites filled with RNS at a mass fraction of 1–5% showed increased break elongation, Young's modulus, and impact strength but almost unchanged or even slightly lowered tensile strength than the unfilled matrix. The DNS‐filled nylon 1010 composites had obviously decreased tensile strength, whereas the incorporation of DNS also contributed to the increase in the Young's modulus of nylon 1010, but less effective than RNS. Moreover, the nylon 1010 composites had better thermal stability than the neat polymer matrix, and the composites filled with RNS were more thermally stable than those filled with DNS. The difference in the crystallinity of neat nylon 1010 and its composites filled with RNS and DNS was subtle, although the surface‐modified nano‐SiO₂ could induce or/and stabilize the γ‐crystalline formation of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetics of the solid‐state polymerization of nylon‐6

The kinetics of the thermally induced solid‐state polymerization (SSP) of nylon‐6 were examined in both a fixed‐bed reactor and a rotary reactor. Factors such as the regulator content, the reaction temperature and time, the particle size, the type and geometry of the nylon‐6 prepolymer, the nitrogen gas flow rate, the water content of the nitrogen gas flow, and the polymerization process were studied. The results showed that the regulator content, the reaction temperature and time, and the particle size were the primary factors, and that the others were negligible. Moreover, the SSP rate and number‐average molecular weight (M_n) increased with increasing reaction temperature and time and decreasing particle size. The SSP rate and M_n had maximum values with increasing regulator content in an experimental range of 0.03–0.07 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 616–621, 2002; DOI 10.1002/app.10341     

Water‐dispersible conducting polyaniline/nano‐SiO2 composites without any stabilizer

A water‐dispersible conducting polyaniline/ nano‐SiO₂ composite, with a conductivity of 0.071 S cm^?1 at 25°C, was prepared by the oxidative polymerization of aniline in the presence of amorphous nano‐SiO₂ particles. And the structure, morphology, thermal stability, conductivity, and electroactivity of this composite were also investigated. This composite has been steadily dispersed in the aqueous solution for about 10–36 h without the need for any stabilizer. It would significantly impulse the commercial applications of conducting polyaniline/nano‐SiO₂ composite as fillers for antistatic and anticorrosion coatings. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A study on the preparation of polymer/montmorillonite nano‐composite materials by photo‐polymerization

The preparation of polymer/montmorillonite intercalation composite materials was studied by two kinds of photo‐polymerization reaction (photo‐acid generation and photo‐radical generation). Small‐angle X‐ray diffraction was used for the structural characterization of montmorillonite contained in the products. Results indicated that, after chemical modification of montmorillonite, the monomer (methyl methacrylate) and the prepolymer (m‐cresol/HMMM) were able to intercalate into the layers of clay and to polymerize ‘in situ’, thus producing photo‐polymerized composite materials. The advantages and shortcomings of the method of photo‐polymerization for the preparation of these composite materials are discussed. © 2001 Society of Chemical Industry     

Preparation of the composite consisting of nano‐sized gold particles and nylon‐11 oligomer

Nylon‐11 oligomer was utilized as a matrix to prepare a composite containing nano‐sized gold particles. Nylon‐11 oligomer was prepared by a thermal degradation of a commercial nylon‐11 in vacuum. Weight‐average molecular weight of the oligomer was in a range from 500 to 800. Nylon‐11 oligomer was formed into a film, and then gold was vapor‐deposited onto the oligomer film. The gold‐colored oligomer film turned a transparent red after a heat treatment at 120°C. Transmission electron microscopy showed an isolated distribution of nano‐sized gold particles in the red film of the oligomer. The gold particles were stable in the oligomer for more than a year, and they were dissolved in CH₂Cl₂ to produce a stable colloidal solution. These results suggest that the gold particles were not only dispersed in the oligomer film, but they were stabilized by the nylon‐11 oligomer to form a composite. IR spectrum of the composite showed that N H groups of the nylon‐11 oligomer were responsible for the interaction between the gold particles and the oligomer. Pulse ¹H‐NMR measurement suggested that an active molecular motion of the nylon‐11 oligomer caused the dispersion of the gold particles. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1654–1661, 1999     

Effect of amphoteric dispersant on the dispersion properties of nano‐SiO2 particles

An amphoteric polycarboxylate dispersant (APC) was synthesized by copolymerization of acrylic acid (AA), methacryloxyethyltrimethyl ammonium chloride (DMC), and isopentenol polyoxyethylene ether (IPEG). The molecular structure of APC was characterized by FT‐IR, ¹H‐NMR, and GPC. Effect of the dosage of APC on the rheological performance of nano‐SiO₂ suspension was investigated by measurements of the plastic viscosity. The results indicated that the best dispersion effect of APC was obtained when the dosage of APC was about 10 wt % (by the weight percent of nano‐SiO₂), which can maintain the dispersion of nano‐SiO₂ suspension uniformly for 4 h without settlement. Meanwhile, the zeta potential value on the surface of nano‐SiO₂ particles shows that the better dispersion performance of APC was attributed to the solvation water film formed by the polyoxyethylene side chains and the electrostatic repulsion formed by positively groups (C?N⁺) on the APC structure combined with ‐SiO^– groups on the surface of nano‐SiO₂ particles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45075.     

Preparation and characterization of nano‐SiO2 reinforced alginate‐based nanocomposite films (II)

Crosslinked alginate‐based nanocomposites at different SiO₂ contents were prepared successfully by blending the nano‐SiO₂ solution into low concentration alginate solution (0.5 wt %), with the alginate concentration increased step by step to the resulted concentration, in this course glycerol was used as plasticizer and 5 wt % CaCl₂ as crosslinker. The combined effect of SiO₂ content (1.5–8 wt %) on the microstructural, physical, mechanical, and optical properties of the nanocomposite films were investigated. The results showed that tensile strength and elongation was improved by about 40.33% and 89%, respectively, upon increasing the SiO₂ content to 4.5 wt %. In addition, water vapor permeability and swelling degree decreased by 19% and 16% with increasing SiO₂ content up to 8 and 4.5 wt %, respectively with respect to pure crosslinked alginate film. Thermogravimetric analysis also revealed that nano‐SiO₂ can improve the thermal stability of sodium alginate films produced by this method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45286.     

Preparation of styrene‐acrylic emulsion by using nano‐SiO2 as seeds

A styrene‐acrylic/SiO₂ nanoparticle composite emulsion was prepared by using SiO₂ nanoparticles as seeds. The effect of factors such as the level of nano‐SiO₂, reaction temperature and ultrasound treatment of nano‐SiO₂ on the stability of the polymerization reaction was investigated. Water‐resistance of the emulsion was measured. The level of nano‐SiO₂ in the emulsion was determined by inductively coupled plasma (ICP) spectrometry. The particle morphology of the emulsion with nano‐SiO₂ was observed with transmission electron microscopy (TEM). The kinetics of the polymerization was also studied at various temperatures and various levels of nano‐SiO₂. They showed that the level of nano‐SiO₂ and reaction temperature had a great influence on the monomer conversion, particle size, coagulum content and viscosity of the emulsion. Nano‐SiO₂ treated by ultrasonics can increase the coagulum content greatly, but it does not improve the water resistance of the emulsion. The level of nano‐SiO₂ in the emulsion was lower than the theoretical value. The reaction kinetics indicated that the level of nano‐SiO₂ had less influence on the reaction rate than the reaction temperature. Even a small amount of nano‐SiO₂ can decrease the reaction rate. Copyright © 2004 Society of Chemical Industry     

Structure and property study of nylon‐6/clay nanocomposite fiber

The crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of flame‐retardant melamine cyanurate/polyamide 6 nanocomposites by in situ polymerization

This article focuses on an improved method, i.e., improved in situ polymerization of ε‐caprolactam in the presence of melamine derivatives to prepare flame‐retardant melamine cyanurate/polyamide 6 (MCA/PA6) nanocomposites. The chemical structures of these synthetic flame retardant composites are characterized by Fourier‐transform infrared spectroscopy and X‐ray diffraction. Morphologies, mechanical properties, and thermal properties also are investigated by the use of transmission electron microscopy, mechanical testing apparatus, differential scanning calorimetry, and thermogravimetric analysis, respectively. Through transmission electron microscopy photographs, it can be found that the in situ‐formed MCA nanoparticles with diametric size of less than 50 nm are nanoscaled, highly uniformly dispersed in the PA6 matrix. These nanocomposites, which have good mechanical properties, can reach UL‐94 V‐0 rating at 1.6‐mm thickness even at a relatively low MCA loading level. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In situ polymerization and characterization of polyamide‐6/silica nanocomposites derived from water glass

Polyamide‐6/silica nanocomposites were prepared via an in situ polymerization route using silicic acid as the precursor of silica, which was extracted from water glass. Scanning electron microscopy observations showed that the silica particles were well dispersed in the polyamide‐6 matrix on the nanometer scale, which demonstrated that this method could effectively avoid agglomeration of the inorganic particles. The coupling agent, (γ‐aminopropyl) triethoxysilane, was added to introduce interfacial interactions between the silica and the polymer matrix, which led to an increased graft of polymer on the silica surface and made the material display higher performance. It was found that the incorporation of the inorganic component significantly increased the melt viscosity, tensile strength, Young's modulus, thermal decomposition temperature, glass transition temperature and Vicat softening temperature of the polyamide‐6 resin. The reinforcement of the silica particles was clearly demonstrated. Copyright © 2004 Society of Chemical Industry     

In situ polymerization and nano‐templating phenomenon in nylon fiber/PMMA composite laminates

Supercritical Carbon Dioxide (SC CO₂) is used as a reaction/processing medium in the fabrication of fiber‐reinforced composite materials. SC CO₂ allows resin (reactive monomer), to penetrate inside the fibers themselves, partitioning into the amorphous regions of the fiber. The crystal structure then templates polymerization of matrix within the fiber. This process produces a composite that exhibits ultralong‐range order from the nanoscale reinforcement of crystals to the macroscale fiber reinforcement of matrix. In addition, SC CO₂ lowers resin viscosity and aids in wetting out Nylon 6,6 fiber reinforcement in a process similar to reaction injection molding (RIM) or resin transfer molding (RTM). This article will discuss the fabrication technique in detail, including process parameters and the structure of resulting composites and morphology of modified fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1600–1607, 2003     

Structure and thermal behavior of nylon‐6/polytetrahydrofuran triblock copolymers obtained via anionic polymerization

The structure, crystallization, and phase behavior of nylon6‐b‐polytetrahydrofuran‐b‐nylon6 triblock copolymers synthesized via activated anionic polymerization have been studied. The composition, molecular weight of polytetrahydrofuran (PTHF) soft block, and type of polymeric activators (PACs) have been varied. Differential Scanning Calorimetry (DSC), Wide‐Angle X‐ray Diffraction (WAXD), Transmission Electron Microscopy (TEM), and Polarized Light Microscopy (PLM) experiments have revealed that in triblock copolymers only the nylon‐6 component crystallizes while PTHF segments are amorphous. The soft blocks do not alter the spherulitic crystalline structure of nylon‐6 and hard blocks crystallize in the α‐modification. The degree of crystallinity decreases with increasing PTHF concentration. The phase behavior has been investigated by Dynamic Mechanical Thermal Analysis (DMTA). Two different glass transition temperatures (T_g) for all samples have been observed. This indicates that nylon‐6 and PTHF segments are not molecularly miscible and the copolymers are microphase separated. The mechanical properties of the copolymers synthesized have been evaluated. Nylon‐6 copolymers with soft block concentrations up to 10 w/w %, exhibit improved notched impact strength in comparison to the nylon‐6 homopolymer, retaining relatively high hardness and tensile strength. All copolymers possess low water absorption and good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1448–1456, 2002; DOI 10.1002/app.10448