有机硅微乳液的研究进展

对近年来有机硅微乳液的研究进展进行了综述，包括有机硅微乳液的制备方法（乳液聚合法和硅油乳化法等），及其在纺织印染，化妆品及医药，表面涂覆等领域的应用。     

Effect of crosslinking on the conductivity of conductive silicone rubber

We investigated the effect of polyvinylsilicone oil (C gum) as a crosslinker and 2,5‐bis(tert‐butyl peroxy)‐2,5‐dimethyl hexane (DBPMH) as a curing agent on the conductivity of conductive silicone rubber with two different kinds of conducting mechanisms. The experimental results show that the volume resistivity of conductive silicone rubber changed with its degree of crosslinking. When the carbon black loading was 25 parts per hundred rubber (phr) and a completely continuous conducting network had not formed, the volume resistivity of the vulcanizates decreased with increasing crosslink density. The volume resistivity of the vulcanizate with a suitable amount of C gum decreased to 53%, and the tensile strength increased by 0.8 MPa compared to the vulcanizate without C gum. When the carbon black loading was 40 phr and a completely continuous conducting network had formed, the crosslink density of vulcanizates changed as the amount of DBPMH changed. The volume resistivity of vulcanizates first decreased and then increased with increasing crosslink density. There was a valley value in the resistivity–crosslink density curve. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3471–3475, 2003     

Preparation of polydimethylsiloxane nanolatices by emulsion polymerization in a water–aminoethanol system

Stable and translucent polydimethylsiloxane nanolatices in a water–aminoethanol (AE) system were prepared by the emulsion polymerization of octamethylcyclotetrasiloxane (D₄) with nonionic polyoxyethylene alcohol ethers and polyoxyethylene aryl ether as surfactants and with KOH as an initiator. The effects of the AE concentration on the emulsion polymerization rate (R_p) of D₄ and the physical properties of the resultant nanolatices were investigated. Increasing the AE concentration in the reaction mixture dramatically increased the emulsion R_p value of D₄, and the kinetics of the D₄ emulsion polymerization in this system were consistent with the Morgan–Kaler theory of microemulsion polymerization. When the AE concentration in the emulsion increased, the transparency value of the resultant emulsion increased, and the size of the droplets in the resultant nanolatices decreased. In addition, the molecular weight of the polysiloxane in the resultant emulsion also increased with the increase in the AE concentration in the reaction mixture. A nanolatex prepared by the emulsion polymerization of 0.98M D₄ with 185 g/L AE had a transparency value of 80.9% and a mean diameter of 59.5 nm. The morphology of polysiloxane nanolatices cured with (N,N‐diethylaminomethyl)‐triethoxysilane was observed with transmission electron microscopy, and the size of the globular particles was consistent with that obtained by dynamic light scattering. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 347–352, 2005     

冷缩型电力电缆附件的技术与应用

简述了电力电缆附件的概况，阐述了冷缩型电缆附件的发展简史、产品的特性及应用范围，系统介绍了冷缩型电缆附件的制备工艺，重点叙述了产品原料的筛选及模具的设计。     

Transient effects in dynamic modulus measurement of silicone elastomers 1. Zero mean strain measurements

The strain‐dependent dynamic storage modulus of a poly(dimethyl‐siloxane‐co‐methylvinyl‐siloxane‐co‐methylphenyl‐siloxane) based silicone elastomer, which is reinforced with fumed silica and crosslinked with peroxide, is investigated. The dependence of the resulting dynamic storage modulus on the duration of cycling at a particular test condition is investigated and compared to static stress relaxation measurements in the same strain range. The dynamic modulus results are shown to depend on the time of cycling at the current test conditions as well as the time of cycling at prior conditions of lower strains. The relaxation is shown to be related to the time of cycling rather than the number of cycles performed. The pattern of behavior of the relaxation of the dynamic modulus with respect to peak strain amplitude is different than that observed in a static stress relaxation test, both of which show significant nonlinear effects in strain. The observed phenomena are interpreted in terms of the role of the polymer phase on the dynamic behavior of the elastomer material. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1001–1009, 2005     

Preparation and characteristics of a waterborne preventive stain coating material with organic-inorganic composites

With the goal of developing a waterborne coating material that prevents staining, organic-inorganic composites prepared from colloidal silica and two types of acrylic resin emulsions were investigated as exterior coatings. conventional acrylic resin emulsion and organic silane hybridized acrylic resin emulsion prepared by emulsion polymerization were mixed with colloidal silica to form organic-inorganic comiposite films. The addition of colloidal silica to emulsions yielded films with higher hydrophilicities, as indicated by lower water contact angles for these films in comparison to films without colloidal silica. The water contact angles of organic silane hybridized acrylic resin emulsion/colloidal silica films were lower than those of acrylic resin emulsion/colloidal silica films. Composite films containing colloidal silica particles smaller than 100 nm in diameter showed high hydrophilicities. Observations of the dispersed state of colloidal silicaparticles in organic-inorganic composite films by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that colloidal silica particles were densely aggregated on the film surface. Outdoor exposure tests of the coating materials prepared from organic silane hybridized acrylic resin and colloidal silica particles with diameters of 7.5 nm showed excellent stain resistance.     

Preparation of positive‐temperature coefficient heaters using platinum‐catalyzed silicone rubber

Various output heaters were extruded with acetylene black–filled platinum‐catalyzed silicone rubber. The resistivity–temperature behavior of extruded heaters exhibited a positive‐temperature coefficient (PTC) effect without any negative‐temperature coefficient (NTC) effect. Resistivity and thermal reproducibility of the extruded heaters were investigated during heating and cooling cycles at an applied voltage of 220 V. These heaters initially showed poor reproducibility of resistivity during the repeated cycles and this effect increased significantly as the acetylene black content decreased. PTC effect and electrical reproducibility were improved significantly during the thermal ageing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1611–1617, 2004     

Synthesis and characterization of nonionic 1‐vinyl‐2‐pyrrolidinone/methacryloxy silicone copolymers: Effects of molecular weight of silicone and crosslinking density

Nonionic 1‐vinyl‐2‐pyrrolidinone/methacryloxy silicone copolymers (VP/VS copolymers) were prepared and characterized as functions of molecular weight of silicone and crosslinking density. Fourier transform infrared spectroscopy, ¹³C‐NMR, and pyrolysis gas chromatography–mass spectrometry study showed that those copolymers were successfully synthesized. Also, the gel‐permeation chromatography spectrum exhibited a fairly narrow distribution of the molecular weight of the polymer. It was found that the turbidity in ethanol (EtOH) and the glass‐transition temperature of crosslinked VP/VS copolymers are influenced by the amount of crosslinking agent. However, in the case of branched VP/VS copolymers, a transparent solution was obtained, regardless of the molecular weight of silicone. SEM/EDS study revealed that silicone is more abundant on the coating surface than on the interface of coating/glass. This is probably because Si‐containing chains have lower surface energy than that of vinylpyrrolidinone‐containing chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2244–2253, 2002     

A novel alkoxysilane‐modified high solids hydroxyl acrylic polyurethane: Preparation and surface properties

Alkoxysilane‐modified high solids hydroxyl acrylic polyurethane was prepared by solution polymerization. Its structure, surface, and thermal properties were investigated by ¹H NMR, device of contact angle, thermo gravimetric analysis (TGA), atomic force microscopy (AFM), and X‐ray photoelectron spectroscopy (XPS). Research showed that alkoxysilane modified high solids hydroxyl acrylic polyurethane has superior properties that can be used for automotive paints. The contents of silicone in the alkoxysilane‐modified high solids hydroxyl acrylic polyurethane were 1.25, 1.5, 2, and 2.5 wt %. In this study, γ‐methacryloxypropyltrimethoxysilane (MPTS) was chosen as the modifier. Results showed that the contact angles of water and surface roughness on the film of MPTS modified high solids hydroxyl acrylic polyurethane increased, and thermal stability of the film at high temperatures improved with the increasing of the silicone content in the resins. MPTS modified high solids hydroxyl acrylic polyurethane with 2.5 wt % silicone content had better water resistance, better acid resistance, higher hardness, and excellent weatherability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1866–1871, 2006     

Effect of peroxide crosslinking on the dynamic modulus of silicone rubber

The effect of peroxide crosslinking on the dynamic modulus of a silica‐reinforced silicone [poly(dimethylsiloxane)] elastomer was investigated. Three different peroxides (t‐butyl peroxide, t‐butyl perbenzoate, and benzoyl peroxide) were employed at various practical loadings and differences in the nonlinear behavior of the dynamic modulus were found. Results are discussed with respect to changes in crosslinking density and the identity of the peroxide. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1504–1512, 2005