Sound insulation in polymer/inorganic particle composites. I. Theoretical model

The sound insulation behavior of inorganic particulate-filled polymer composites was analyzed by means of acoustics theory in this article to reveal the mechanisms of sound insulation. On the basis of it, a physical model of the sound wave transfer in the composite system was established, and a relevant transmission loss equation was derived. The transmission loss of the glass bead-filled polyethylene composites was estimated by using this equation. The results showed that the calculated transmission loss of the composites increased linearly with an increase of the glass bead volume fraction, and it increased nonlinearly with increasing sound frequency. The sensitivity of the transmission loss to the sound frequency was significant at low sound frequency. The transmission loss decreased nonlinearly with the size of added glass bead when the volume fraction was constant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of polarity of polymer on inorganic particle dispersion in dielectric particle/polymer composite systems

The influence of the polarity of polymers on the degree of dispersion of BaTiO₃ particles in BaTiO₃/polymer composite systems was investigated. The BaTiO₃ polymer composite systems were prepared from BaTiO₃ particles and low-density polyethylene (LDPE) or ethylene vinyl acetate copolymer (EVA) with 7 and 15 wt % vinyl acetate. Scanning electron microscopy observation showed that BaTiO₃ particles aggregated in the polymer matrices and dispersed more readily into the EVA matrix than into LDPE. The shift of the β-peak temperature by ca. +5°C in the temperature dispersion of the loss modulus was observed for EVA–BaTiO₃ composite systems in dynamic mechanical property measurement. On the other hand, the β-peak temperature of the polymers filled with graphite particles, which have hydrophobic surfaces, was almost constant in a volume fraction region of 0–0.3. The ellipsoidal axes' ratios given by comparison of experimental dielectric constant values and theoretical ones using the Maxwell equation were 4.2, 3.6, and 3.1 for LDPE/BaTiO₃, EVA(7%)/BaTiO₃, and EVA(15%)/BaTiO₃ composite systems, respectively. The axes' ratio decreased by the introduction of polar vinyl acetate groups into nonpolar LDPE. The results confirmed that the polarity of the polymers was one of the key factors governing the dispersibility of BaTiO₃ particles in the polymer matrix. © 1995 John Wiley & Sons, Inc.     

Preparation of polymer/inorganic nanoparticles composites through ultrasonic irradiation

In this paper, ultrasonic induced encapsulating emulsion polymerization was first used to prepare the novel polymer/inorganic nanoparticles composites. The behaviors of several inorganic nanoparticles (SiO₂, Al₂O₃, TiO₂) under ultrasonic irradiation, such as dispersion, crushing, and activation, were studied. The dispersion stability, morphology, and structure of the ultrasonic irradiated nanoparticles were characterized by means of transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and spectrophotometry, respectively. The results show that the inorganic nanoparticles in the aqueous solution can redisperse more effectively by ultrasonic irradiation than by conventional stirring. This is the basis for preparation of polymer/inorganic nanoparticles composites. By this technique, the long‐term stable latex, which mainly consists of polymer/inorganic nanoparticles composite latex particles, were successfully prepared. TEM, FTIR, thermogravimetric analysis, X‐ray photoelectron spectroscopy, spectrophotometry, and element analysis confirmed that well‐dispersed nanoparticles were encapsulated by the formed polymer, and the thickness of encapsulating polymer layer was in the range of 5–65 nm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1478–1488, 2001     

Quantitative description of interfacial strength in polypropylene/inorganic particle composites

The parameters characterizing the interfacial adhesion strength, such as interaction parameter (B) and interfacial adhesion angle (θ), of inorganic particulate‐filled polymer composites were analyzed in this paper. On the basis of the previous studies and the research work reported in literature, several expressions for predicting these parameters and the determination methods of these parameters were proposed, and the relationship between the interaction parameter and interfacial adhesion angle was discussed. Then the parameters B and θ were estimated from the experimental measured tensile strength of the several inorganic particulate‐filled polypropylene (PP) composites including nanometer calcium carbonate, glass bead and diatomite particles. The results showed that the value of θ was about from 44 to 75 degrees while the value of B was varying from 1.12 to 2.42 of these filled systems under the experimental conditions. Moreover, the value of B decreased roughly linearly with increasing θ for these particulate‐filled PP composites.POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Prediction of elastic properties for curved fiber polymer composites

The objective of this article is to study the effect of fiber curvature on the elastic properties of a long‐fiber composite. The study was carried out using a unit cell homogenization approach and micromechanical modeling. In the first approach, a unit cell with a fiber bundle was defined and used in the analysis. Appropriate boundary conditions were prescribed to extract the elastic stiffness components. The second approach made use of the Eshelby‐Mori‐Tanaka model to compute the stiffness of the aligned fiber composite. Fiber curvature was then accounted for through the variation of fiber orientation within a prescribed range that corresponds to a given degree of fiber curvature. It was found that curved fibers significantly affect the composite properties since they lead to a significant stiffness reduction in the longitudinal direction while relatively small increase in stiffness is achieved in the transverse direction in the plane containing the fiber tow. POLYM. COMPOS., 2008. Published 2008 Society of Plastics Engineers     

麻纤维/聚合物复合材料

综述了近年来麻纤维/聚合物复合材料的研究进展,重点阐述了环境友好型复合材料的界面处理、成型工艺及性能研究.     

聚合物/无机纳米粒子复合材料的研究进展

综述了无机纳米氧化物(如SiO2、TiO2、Al2O3)、纳米硅化物(如SiC、Si3N4)和纳米CaCO3作为填充材料对聚合物材料物理、化学、热学、光学、力学及摩擦学性能的改善作用,在聚合物中加入纳米粒子是制备高性能复合材料的重要手段之一。     

环氧树脂/无机纳米材料复合研究进展

概述了环氧树脂/无机纳米材料的复合方法,分体系综述了环氧树脂/粘土、环氧树脂/纳米SiO2、环氧树脂/纳米TiO2复合的最新研究进展情况,并介绍了一种新的复合体系-环氧树脂/凹凸棒土复合体系。     

Viscoelastic properties and characterization of inorganic particulate‐filled polymer composites

To identify effects of glass bead (GB) content on the dynamic mechanical properties of filled low‐density‐polyethylene (LDPE) composites, the storage modulus, loss modulus, glass transition temperature, and mechanical damping of these composites were measured using a Du Pont dynamical mechanical analysis instrument in temperature range from ?150 to 100°C. It was found that the storage modulus increased nonlinearly with an increase of the GB volume fraction. On the basis of Eshelby's method and Mori's work, an equation describing the relationship between the relative storage modulus (E′_R) and filler volume fraction for polymeric composites was proposed, and the E′_R of LDPE/GB composites were estimated by means of this equation at temperatures of ?25, 0, and 25°C, and the calculations were compared with the experimental data, good agreement was showed between the predictions and the measured data. Furthermore, this equation was verified by the experimental from Al(OH)₃ filled EPDM composites at glassy state reported in a reference. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

聚合物／聚合物分子复合材料的研究动态

综合讨论了聚合物／聚合物分子复合材料的定义、特征和优势,重点介绍了分子复合材料相容的有效途径及分子复合材料的常用制备方法。并简述了热固性分子复合材料的研究情况及分子复合材料研究前景。     

RAFT/MADIX polymers for the preparation of polymer/inorganic nanohybrids

Organic–inorganic hybrid nanocomposites are an emerging class of materials that hold significant promise due to their outstanding properties, which usually arise from a combined and/or synergistic effect of the properties of their organic and inorganic components. Despite the numerous functionalization methods described in literature, only a few of them allow precise and easy control of the chemical composition and structure of the organic shell, whereas this point is critical to control some of the nanohybrids properties such as solubility, specific interaction and so forth. In this context, reversible addition-fragmentation chain transfer polymerization/macromolecular design by interchange of xanthates (RAFT/MADIX) technology is a fantastic tool that can be easily performed in mild and “green” conditions, being compatible with a huge variety of functional monomers and providing an excellent control of the organic shell characteristics. This review aims to describe the state of the art of the use of RAFT/MADIX polymers for the preparation of these nanohybrids. After describing the most commonly used synthetic strategies for nanohybrids preparation, the main families of polymers are discussed in view of their chemical composition (homopolymer, copolymer, …) and/or the targeted properties (hydrophilic, hydrophobic, stimuli-responsive). The main advantages of RAFT/MADIX technology are discussed in terms of the numerous applications of those materials.     

Polyoxometalates/polymer composites for the photodegradation of bisphenol-A

Nowadays water scarcity represents a threat for human and living beings. Therefore, to satisfy the demands of people for clean and safe water, new technologies for wastewater treatment have been developed. Thus, photocatalysis has emerged as a green chemical approach for such treatment. In this context, new polyoxometalate (POM)/polymer composites with relevant photocatalytic properties have been developed via an easy and cheap photopolymerization process upon mild visible light irradiation at 405 nm. This fruitful association between POM and polymer allowed the obtention of shaped materials facile to collect and reuse at the end of the photocatalytic treatment avoiding then the usual time-consuming regeneration methods. The prepared photocomposites displayed excellent photocatalytic performance for the removal of bisphenol-A from water under different sources of irradiation. Hence, 100%, 88%, and 50% of this model compound were decomposed by the phosphomolybdic composite under just 90 min of UV lamp, solar and LED@375 nm irradiations, respectively. The effectiveness of these developed photocatalysts towards the degradation of other organic compounds, as well as the degradation mechanism based on the generation of highly reactive chemicals such as ^•OH radicals promoting the degradation were already reported. Bisphenol-A degradation pathway and the identification of the photoproducts were discussed using mass spectroscopy technique. Therefore, this paper highlighted the photocatalytic efficiency of the new manufactured materials for the photodegradation of the bisphenol-A, thus expanding their application fields, under different sources of irradiation and under pure solar irradiation which make their applications more interesting and less energy consuming.     

New photoinitiating systems designed for polymer/inorganic hybrid nanocoatings

Conventional UV-curable formulations consist of photoinitiators, multifunctional monomers and oligomers, reactive diluents, pigments, and additives. While photoinitiators are the key components of the formulations and responsible for the absorption of light and relevant performances (e.g., cure speed, high-percent conversion, etc.), the final properties of the cured coating are governed by the other high-volume components. With recent advances in the use of nanomaterials like metals, metal oxides, and silicates in coatings, it is now possible to prepare nanocoatings with enhanced physical, chemical, and biological properties. This is due, in part, to the difference in surface area per unit of volume at the nanoscale. Nanocoatings are usually prepared by UV irradiation of formulations containing dispersed nanoparticles. However, the homogeneous dispersion of these nanoparticles is a key challenge due to their easy agglomeration arising from their high surface-free energy. It is often difficult to obtain well-dispersed formulations providing good transmission of light for a complete cure. In this article, we report several synthetic methodologies for the preparation of epoxy and (meth)acrylate-based nanocoatings containing clay or metal nanoparticles. In the former case, photolysis of intercalated photoinitiator within the layers of montmorillonite clay in the presence of monomers resulted in the in situ formation of exfoliated structures. For the preparation of metal nanocoatings, the formation of silver or gold nanoparticles and crosslinking are accomplished simultaneously by photoinduced electron transfer and polymerization processes. The nanoparticles are homogenously distributed in the network without macroscopic agglomeration. Applicability to both free radical and cationic systems is demonstrated. Moreover, a novel photochemical route for grafting from the self-assembled monolayers on gold is presented.     

Predictions of young's modulus of inorganic fibrous particulate‐reinforced polymer composites

In this study, the factors affecting the Young's modulus of inorganic fibrous particulate‐reinforced polymer composites were analyzed, and a new expression of the Young's modulus was derived and was based on a simplified mechanical model. This equation was used to estimate the composite Young's modulus. The estimated relative Young's modulus increased nonlinearly with increasing filler volume fraction. Finally, we verified the equation preliminarily by quoting the measured Young's modulus values of poly(butylene terephthalate)/wollastonite, polypropylene/wollastonite, and nylon 6/wollastonite composites reported in the literature. Good agreement was shown between the predictions and the experimental data of the relative Young's modulus values for these three composite systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2957–2961, 2013     

聚合物/无机纳米复合材料研究进展

综述了提高有机,无机纳米复合材料性能的技术。聚合物的纳米复合技术经历了一个从物理到化学的过程。多面体低聚倍半硅氧烷的出现,实现了通过制备可官能化的纳米粒子,使聚合物和无机纳米材料达到真正意义上的化学结合。     

Synthesis of polymer/inorganic nanocomposite films using highly porous inorganic scaffolds

Polymeric/inorganic nanocomposite films have been fabricated through a combination of flame-spray-pyrolysis (FSP) made inorganic scaffold and surface initiated polymerization of cyanoacrylate. The highly porous structure of pristine SnO(2) films allows the uptake of cyanoacrylate and the polymerization is surface initiated by the water adsorbed onto the SnO(2) surface. Scanning electron microscopy study reveals a nonlinear increase in the composite particle size and the film thickness with polymerization time. The structural change is rather homogeneous throughout the whole layer. The composite is formed mainly by an increase of the particle size and not by just filling the existing pores. High-resolution transmission electron microscopy imaging shows SnO(2) nanoparticles embedded in the polymeric matrix, constituting the nanocomposite material. Thermogravimetric analysis indicates that the porosity of the nanocomposite films decreases from 98% to 75%, resulting in a significant enhancement of the hardness of the films. DC conductivity measurements conducted in situ on the nanocomposite layer suggest a gradual increase in the layer resistance, pointing to a loss of connectivity between the SnO(2) primary particles as the polymerization proceeds.     

Effects of polymer molecular weight and filler particle size on flow behavior of wood polymer composites

The influence of polymer matrix molecular weight and filler particle size on rheological properties and extrudate distortions of metallocene polyethylene (mPE)/wood flour (WF) composites has been investigated by rotational and capillary rheometers. It was found that at low shear rates smaller filler particles provide higher shear viscosity than the larger sized filler. At high shear rates and WF loadings above 30 wt%, the effect of particle size on the melt flow properties becomes negligible. The relative increase of the storage modulus with decreasing particle size is more pronounced in the case of low molecular weight polymer matrix than that in higher molecular weight polyethylene based composites. The wood filled polyethylenes exhibit extrudate surface defects, which are complex function of the shear rate, polymer matrix molecular weight, and filler particle size. Increasing the shear rate results in pressure oscillations and spurt‐flow. It was also observed that the evolution of the extrudate surface tearing is strongly dependent on the pressure during a single pressure oscillation cycle in the spurt flow regime. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

凹凸棒土/聚合物复合材料研究进展

综述了凹凸棒土在聚合物中的应用研究进展。研究表明，大多数情况下，常规的聚合物加工技术不足以将凹凸棒土解离为纳米短纤维，因此只能形成凹凸棒土／聚合物微米复合材料，但将凹凸棒土进行有机改性，可以明显提高其增强效果。采用原位聚合的方法可以制备出性能优异的凹凸棒土／聚合物纳米复合材料，或在高黏度和高极性的聚合物熔体中，凹凸棒土在剪切力下可以解离为纳米单晶，从而形成纳米复合材料。利用凹凸棒土／乳液共混共凝方式也可制备出凹凸棒土／橡胶纳米复合材料。     

聚氨酯/无机纳米复合材料研究进展

阐述了近年国际国内在制备聚氨酯（PU）/无机纳米复合材料方面的研究进展情况,针对碳纳米管（CNTs）、石墨烯、氧化物纳米粒子、层状硅酸盐（PLS）等不同种类的无机纳米材料-聚氨酯复合体系研究重点、制备方法及性能特点进行了介绍,并对今后的研究应用方向和趋势做出了展望：将进一步研究无机纳米材料在聚氨酯基体具有更微观层次良好分散性的制备方法;复合材料微观相界面、反应机理方面的理论性研究将更为深入;无机纳米材料选择种类进一步延伸,拓展具有优异综合性能的多元复合体系研究领域;简化复合体系合成途径,降低生产成本,加快聚氨酯复合材料工业化进程。     

Effects of filler on heat transmission behavior of flowing melt polymer composites

A probe consisting of a cartridge heater was inserted into melted polypropylene composites (PP/mica = 5, 10, and 20 wt%) flowing in a die having a diameter of 10 mm, and the effects of mica on the heat transfer coefficient and the heat transfer behavior from the surface of the probe to the flow compound material were examined experimentally. As a result, the heat transfer coefficient of the PP/mica composites increases 15–20% depending on the flow velocity and filler content. In general, the Prandtl number (Pr) for high‐viscosity (η) melted polymer is greater than one (Pr > 1), and the Prandtl number for polypropylene composites increases as the viscosity increases and decreases depending on the flow velocity and the temperature. The relationship between Pr and η is directly proportional, and the β value, which is given by the slope of the Pr ? η diagram, is a constant that shows the viscosity dependency of the Prandtl number. The β value can be determined by the ratio of the specific heat to the thermal conductivity. The Nusselt number depends on the mica content of the filler and increases gradually. POLYM. ENG. SCI. 46:1387–1393, 2006. © 2006 Society of Plastics Engineers