Sound absorption properties of polyurethane/nano‐silica nanocomposite foams

In this study, polyurethane (PU)/nano‐silica nancomposite foams were prepared. The effects of isocyanate index, cell size, density, and molecular weight of polyols on the sound absorption ratio of PU/nano‐silica foams were investigated. With increasing nano‐silica content, the sound absorption ratio of PU/nano‐silica foams increases over the entire frequency range investigated in this study. Decrease of isocyanate index, cell size, and increase of density leads to the increase of sound absorption ratio of PU/nano‐silica foams. PU/nano‐silica foams have a broad T_g centered around room temperature by decreasing molecular weight of polyol resulting in good sound absorbing ability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

原位聚合法制备聚酯聚氨脂SiO2纳米复合涂料及性能测试

论述用原位聚合法制备了聚酯聚氨酯/SiO_2纳米复合涂料,并利用动态力学分析仪(DMA)、傅立叶变换红外光谱(FT-IR)、紫外可见光谱(UV-VIS)、透射电子显微镜(TEM)、原子力显微镜(AFM)、电子拉力机(Instron Tester)测试了涂膜的性能。结果表明,纳米SiO_2粒子均匀分布在涂膜中,并与聚酯通过化学键结合。纳米SiO_2粒子的加入提高了涂膜的摆杆硬度、玻璃化转变温度及附着力,并极大地改变了界面形貌,但本文研究的纳米SiO_2对聚酯聚氨酯紫外线吸收性和耐磨性没有明显影响。     

Preparation and characterization of acrylic latex/nano‐SiO2 composites

Acrylic/nano‐silica composite latexes were prepared by blending via high shear stirring (SS) or ball milling (BM) and in situ polymerization (IS). For comparison, composites filled with micro‐silica were also prepared. The mechanical and optical properties of the polymers formed by the composite latex filled with nano‐ or micro‐silica were investigated using an Instron testing machine, by dynamic mechanical analysis, ultraviolet–visible spectrophotometry and transmission electron micrography. The results showed that SS and BM methods could obtain better nanocomposite latex and polymers than the IS method, characterized by better dispersion of nanoparticles, higher tensile strength and T_g for SS and BM than for IS. The increase in absorbance and reduction in transmittance of UV (290–400 nm wavelength) were observed as nano‐silica content increased, whereas the UV absorbance or transmittance basically were kept unchanged for the composites filled with micro‐silica. © 2002 Society of Chemical Industry     

In situ polyurethane/silica composite formation via a sol‐gel process

Polyurethane acrylate anionomer (PUAA)/silica composite gels were prepared by the sol‐gel reaction of tetraethoxysilane (TEOS) and methacryloxypropyl trimethoxysilane (MPTS) incorporated to PUAA gels by using a swelling method. The formation and structure of composites were confirmed by FTIR, X‐ray diffraction, and SEM. As a result, we found that silica components in composites are located within the ionic domains of their gels and interacted with PUAA via hydrogen bonding. This drastically enhanced the mechanical properties of the composites. Mechanical properties are also improved by MPTS, because MPTS improves the dispersibility and adhesion of silica components in PUAA/silica composite gels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2327–2334, 2002     

Synthesis of flame retardant polyester‐urethanes and their applications in nanoclay composites and coatings

This paper describes the synthesis of phosphorus‐containing polyester‐urethanes and their applications in nanoclay composites and coatings. Polyester was prepared by the reaction of bis(bisphenol‐A) monophenyl phosphonate, maleic anhydride and phthalic anhydride. The polyester was reacted with various diols such as ethylene glycol, diethylene glycol and propylene glycol to obtain polyester polyols. Synthesized polyester polyols were characterized by chemical analysis and instrumental analysis and was used further to react with different isocyanates to develop polyester‐urethanes. The synthesized polyester‐urethanes were blended with organo‐modified montmorillonite nanoclay (1 wt%, 3 wt% and 5 wt%) and were cast in a mold and coated on mild steel panels. The thermal stability of neat polyester‐urethane and the nanoclay composites was determined by thermogravimetric analysis. The flame retardant properties of cast films and their composites were determined by the limiting oxygen index and UL‐94 test methods. The physical and mechanical properties of coatings such as pot life, drying properties, scratch hardness, pencil hardness, impact resistance, adhesion and flexibility were investigated. The chemical resistance properties of the coatings were also determined in different reagents. The data reveal that the polyester‐urethane nanoclay composites with 3 wt% clay hold promise for use in effective flame retardant coatings. © 2013 Society of Chemical Industry     

水性聚氨酯包封原生SiO2纳米复合材料的制备及表征

主要研究了SiO2 /水性聚氨酯 (WPU)无机 -有机纳米复合物的制备方法。TEM和动态光散射分析表明 ,SiO2 /WPU纳米复合物粒子分散于WPU胶束内部 ,粒径在 60nm左右 ,具有核 -壳型结构的纳米级微粒。体系有着良好的稳定性和透光性 ,并且其随着SiO2 含量的增加而降低。胶束良好的包覆作用 ,抑制了纳米粒子的团聚 ,是保持其良好的稳定性和较小粒径的原因     

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     

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     

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 and properties of nano‐Al2O3 particles/polyester/epoxy resin ternary composites

This article presents the results of an experimental study on the preparation and properties of new ternary composites composed of nano‐Al₂O₃ particles, polyester, and epoxy resin. The ternary composites were prepared by the addition of the nano‐Al₂O₃ particles in a binary matrix, with elevated viscosity, of the epoxy resin modified by the polyester. The nano‐Al₂O₃ particles were previously located and dispersed in the polyester phase. The study showed that the ternary system was a type of nanoscale dispersed composite with high strength and toughness as well as modulus, combined with excellent dielectric and heat‐resistance properties. All related properties of the composites were remarkably superior to those of both the binary matrix and the unmodified epoxy resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 70–77, 2002     

Synthesis of hyperbranched polyester‐amides and their application as crosslinkers for polyurethane curing systems

A series of hyperbranched polyester‐amides (S1, S2, S3) with trimethylolpropane as a core molecule were synthesized using core‐dilution/slow monomer addition strategy. The products were characterized by FTIR, ¹³C NMR, GPC, TGA, hydroxyl value measurement, and viscosity measurement. The result showed that the hyperbranched polyester‐amides synthesized had narrow molecular weight distribution and high degree of branching (DB). The hyperbranched polyester‐amides synthesized were used as crosslinkers for polyurethane curing systems and the mechanical properties of the polyurethane curing systems were investigated. It was found that the best tensile property and tear strength were obtained when the S2 were used as crosslinkers and the molar ratio of  OH and  NCO was 1 : 1. It was also found that the polyurethane curing systems had the highest hardness and T_g when the S3 were used as crosslinkers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

改性纳米二氧化硅–丙烯酸酯聚氨酯乳液的制备及表征

以自制改性纳米Si O2水分散液、异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(N210)及甲基丙烯酸甲酯(MMA)等为原料,通过乳液聚合法制得改性纳米Si O2–丙烯酸酯聚氨酯乳液(Si O2–PUA)。通过傅里叶变换红外光谱、Zeta电位测试、热重分析和粒径分布测试等手段对乳液进行了表征,测试了漆膜的硬度、吸水率和耐醇性等性能,探讨了纳米Si O2添加量的影响。当纳米Si O2的添加量≤PUA含量的5%时,Si O2–PUA在469 cm-1处出现了明显的Si─O键弯曲振动峰,而PUA则没有,说明纳米Si O2与PUA可能发生了化学键合。添加5%改性纳米Si O2后,PUA乳液的Zeta电位由-46.5 m V变为-40.1 m V,绝对值减小,稳定性较好;热分解温度比PUA提高了35°C;胶粒平均粒径在纳米级,且Si O2粒子分散均匀;其漆膜硬度提高至4H,吸水率降为10.35%。     

Epoxy/nano‐silica composites: Curing kinetics,glass transition temperatures,dielectric, and thermal–mechanical performances

Nano‐silica particles were employed for enhancement of epoxy vacuum pressure impregnating (V.P.I.) resin. The influences of nano‐silica particles on the curing reaction, glass transition temperatures, dielectric behavior, and thermomechanical performances were investigated. The activation energy (E) for the epoxy curing reaction was calculated according to Kissinger, Ozawa, and Friedman‐Reich‐Lev methods. The glass transition temperatures were determined by means of differential scanning calorimetry, dynamic mechanical analysis, dc conduction, and ac dielectric loss analysis. Relationships between the glass transformation behaviors, the thermomechanical performances, and the dielectric behaviors were discussed. The influences of nano‐silica particles on the mechanical properties were also discussed in terms of non‐notched charpy impact strength and flexural strength. The morphologies were studied by means of SEM and TEM. The results indicated that nano‐silica particles could effectively increase both the toughness and strength of epoxy resin at low loadings (no more than 3 wt %) when nano‐silica particles could be well dispersed in epoxy matrix without any great aggregations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Particle size and morphology of poly[styrene‐co‐(butyl acrylate)]/nano‐silica composite latex

Nanocomposite latex with nano‐silica of varying particle sizes was prepared via in situ polymerization and investigated by submicron particle size analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier‐transform infrared spectrometry (FTIR) and Raman spectrometry. It was found that nanocomposite latex exhibited a core–shell structure with nano‐silica particles enwrapped, resulting in an increase in the latex particle size. The smaller the nano‐silica particles, the more were embedded in each latex particle. The increase in the particle size of latex depended not only on the particle size of nano‐silica, but also on the number of nano‐silica particles in each latex particle. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of novel addition cured polydimethylsiloxane nanocomposites using nano‐silica sol as reinforcing filler

A series of novel addition cured polydimethylsiloxane (PDMS) nanocomposites with various amounts of nano‐silica sol were prepared via hydrosilylation for the first time. The influence of various amounts of nano‐silica sol on the morphology, thermal behavior, mechanical and optical properties of these PDMS nanocomposites was studied in detail. It was found that with an increment in the amount of nano‐silica sol the reinforcing effect of the nano‐silica sol on the thermal and mechanical properties of the PDMS nanocomposites was very noticeable compared with the reference material. The prominent improvements in resistance to thermal degradation and mechanical properties can probably be attributed to the strong interaction of PDMS chains and uniformly dispersed particles resulting from the nano‐silica sol. However, the transparency of the PDMS nanocomposites slightly decreased with an increment in weight fraction of nano‐silica, compared with that of PDMS composite without nano‐silica (Sol‐0), which can probably be ascribed to an increasing size of the aggregated particles in the PDMS nanocomposites. The optimum amount of nano‐silica sol for preparing novel addition curing PDMS nanocomposites was about 15 wt%. © 2015 Society of Chemical Industry     

Synthesis of Na+‐montmorillonite/amphiphilic polyurethane nanocomposite via bulk and coalescence emulsion polymerization

Polyurethane/clay nanocomposites have been synthesized using Na⁺‐montmorillonite (Na⁺‐MMT)/amphiphilic urethane precursor (APU) chains that have hydrophilic polyethylene oxide (PEO) chains and hydrophobic segments at the same molecules. Nanocomposites were synthesized through two different crosslinking polymerization methods. One is UV curing of melt mixed APU/Na⁺‐MMT mixtures; the other is coalescence polymerization of APU/Na⁺‐MMT emulsions. These two kinds of composites had intercalated silicate layers of Na⁺‐montmorillonite by insertion of PEO chains in APU chains, which was confirmed by X‐ray diffraction measurement and transmission electron microscopy. These composite films also showed improved mechanical properties compared to pristine APU films. Although the two kinds of nanocomposites exhibited the same degree of intercalation and were synthesized based on the same precursor chains, these nanocomposite films had the different mechanical properties. Nanocomposites synthesized using APU/Na⁺‐MMT emulsions, having microphase‐separated structure, had greater tensile strength than those prepared with melt‐mixed APU/Na⁺‐MMT mixtures. Location of intercalated Na⁺‐MMT by PEO chains at the oil–water interface also could be confirmed by rheological behavior of the APU/Na⁺‐MMT/water mixture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3130–3136, 2003     

Degradation profiles of polyester‐urethane (HP‐MDI) and polyester‐melamine (HP‐HMMM) coatings: A thermal study

This article investigates the effect of diol structure and acetoacetylation of the hydroxylated polyesters (HPs) on thermal stability and degradation profiles of HPs/hexamethoxymethylmelamine (HMMM) as well as HPs/diphenylmethane diisocyanate (MDI) high solids coatings (HSCs) by thermogravimetry. Thermal stability of HP‐MDI and HP‐HMMM coatings constitute the main focus of this investigation. It is found that variations in the constituent groups to synthesize HPs and acetoacetylation of HPs are important to achieve superior performance. Results of this study indicated a good thermal stability of coatings. However, not much variation in thermal stability was observed with the structural variations in HPs. Mathematical equations of Broido, Coats‐Redfern, and Chang were used to evaluate the kinetic parameters. Activation energy was found to be dependent on the kinetic methods used. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 518–526, 2005     

In situ emulsion polymerization and characterization of PVAc nanocomposites including colloidal silica nanoparticles for wood specimens bonding

Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of T_g (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48570.     

Properties and preparation of thermoplastic polyurethane/silica hybrid using sol–gel process

A thermoplastic polyurethane elastomer/silica hybrid (TPU/SiO₂) was prepared using the sol–gel process. This work was undertaken to investigate the thermal and physical properties of this type of hybrid by employing different catalyst systems during sol–gel processing. Two types of catalyst systems including acetic acid (HOAc) and hydrochloric acid (HCl) were used to prepare sol particles. The mixing of the sol solution and TPU solution was then carried out to form a TPU/silica hybrid. Fourier transform IR spectra and dynamic mechanical properties were recorded to depict the enhanced interfacial interaction. Thermogravimetric analysis was used to determine the actual silica content forming in the hybrid and to evaluate the heat resistance of the hybrid. Mechanical properties such as the tensile strength and cutting strength were investigated at various concentrations of in situ silica. The tensile strength increased at all concentrations of silica. In contrast, the cutting strength decreased, probably because of a reduction of the energy dissipation from silica as physical crosslinks. The HOAc catalyzed system showed better optical properties than the HCl catalyzed system. The fracture surface was revealed through scanning electron microscopy to observe the degree of dispersion of SiO₂, which in turn confirmed the results for the optical and mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1316–1325, 2005     

The influence of interphase on nylon‐6/nano‐SiO2 composite materials obtained from in situ polymerization

Three commercially available silane, titanate and aluminate based coupling agents were used to pretreat nano‐SiO₂ for the preparation of nylon‐6/nano–SiO₂ composites via in situ polymerization. The interphases formed in different composite systems and their influence on material properties were investigated. Results indicated that the interfacial interactions differed between composite systems, whereas rigidity and toughness of composites were all improved by addition of pretreated silicas at an optimal content of 4.3 wt%. The presence of pretreated silicas did not have a distinct influence in the non‐isothermal crystallization behaviour of the nylon matrix. The composites containing pretreated silicas had slightly higher dynamic viscosities and superior storage moduli at high frequency, compared with neat nylon‐6. Copyright © 2003 Society of Chemical Industry