纳米SiO2对有机硅树脂增强加成型硅橡胶性能的影响

以由单官能硅氧单元和四官能硅氧单元组成的有机硅树脂(简称MQ硅树脂)增强加成型硅橡胶为基体,采用机械共混方式加入少量纳米S iO2,研究了纳米S iO2对MQ硅树脂增强硅橡胶的性能影响。结果表明,纳米S iO2在硅橡胶中以聚集体的形式存在,大小约为几十到几百纳米;纳米S iO2填充MQ硅树脂增强的硅橡胶的邵尔A硬度、拉伸强度和扯断伸长率与未填充纳米S iO2的硅橡胶基本相当,撕裂强度增大;其高温热稳定性优于未填充纳米S iO2的硅橡胶,但其透明性稍有下降。     

Improvement of toughness in polypropylene nanocomposite with the addition of organoclay/silicone copolymer masterbatch

Polypropylene nanocomposites were prepared with organic‐modified montmorillonite, by blending the polymer and the organoclay (direct addition), or by blending the polymer with an organoclay/silicone copolymer masterbatch. The effect of the organoclay/silicone copolymer masterbatch on the morphology and properties of polypropylene was compared with that nanocomposite obtained with the direct organoclay addition. The results showed that the morphology of both polypropylene nanocomposites is constituted by clay tactoids together with some few individual platelets and clay aggregates. Smaller tactoids were observed for the nanocomposite prepared with the masterbatch, in which the silicone copolymer remained intercalated in the clay or adjacent to tactoids. The introduction of the organoclay in the polymer matrix resulted only in an increase in the Young's modulus (28%), while yielding stress, elongation at break and Izod impact strength remained practically unchanged. On the other hand, the incorporation of organoclay by using the masterbatch resulted in a marked improvement (111%) in the elongation at break and in Izod impact strength (85%). The improvement in the elongation at break came with the reduction of the modulus and the yielding stress, by 25 and 15%, respectively. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

纳米二氧化钛对MQ硅树脂增强硅橡胶性能的影响

以MQ硅树脂增强加成型硅橡胶为基体,采用机械共混方式,加入少量纳米二氧化钛进行改性,制备了纳米二氧化钛改性硅橡胶。试验结果表明,MQ硅树脂增强的硅橡胶中,加入少量纳米二氧化钛改性后,能够改善硅橡胶的力学性能,其硬度和断裂伸长变化不大,而拉伸强度和抗撕强度提高,硅橡胶的耐热性也提高。溶胀实验表明,添加纳米粒子后,硅橡胶的溶胀比降低,凝胶质量分数和交联密度增加。     

Processing and properties of recycled polypropylene modified with elastomers

Abstract

This work presents a study of the processability and the characterisation of blends of recycled polypropylene (PP) with two different elastomers. The aim of the work was to demonstrate that the introduction of an elastomeric phase could improve the properties of recycled PP without changing the processing characteristics of the blends in terms of viscosity and temperature. The study was carried out using thermal analysis, thermomechanical analysis and rheological measurements. The rheological analysis of blends of recycled PP and elastomeric additives showed that, despite the different rheological behaviour of the added elastomers, the properties of the blends were dominated by the thermoplastic (PP) phase. A thermogravimetric analysis of the selected blends allowed the calculation of the parameters related to the thermal degradation of such materials and the main results indicated that there were no significant differences between virgin and recycled PP in terms of behaviour at high temperatures. Furthermore, the blending of recycled PP with elastomers did not result in a significant change in thermal degradation behaviour. Crystallisation studies showed that blending polypropylene with elastomers influenced the rate and amount of crystallisation, which increased at low additive concentrations and then decreased at a higher elastomer content. Thermomechanical analysis showed the immiscible character of the blends. The mechanical properties of the blends were affected by the concentration of elastomer, which also influenced the crystallinity of the material.     

质子辐照对MQ硅树脂增强加成型硅橡胶力学性能的影响

采用空间综合辐照模拟设备研究了100keV和150keV能量的质子辐照对MQ硅树脂增强加成型硅橡胶力学性能的影响。结果表明,辐照后材料表面产生老化裂纹,随辐照能量、粒子注量的增加,裂纹的数量增多,裂纹增大;质子辐照对硅橡胶的力学性能影响较大,邵尔A硬度、拉伸强度和扯断伸长率随辐照粒子注量的增大先增加而后下降;小粒子注量的辐照对硅橡胶的损伤较小,以交联为主,而大粒子注量的辐照则以降解为主;高辐照能量对硅橡胶的损伤更为严重。     

Blends of polypropylene with solid silicone additive

Blends of polypropylene (PP) and silicone masterbatch (SMB_PP)—a commercial formulation consisting of an ultrahigh molecular weigh polydimethylsiloxane (PDMS) dispersed in PP—were prepared by melt mixing in an internal mixer. Four binary blends with different SMB_PP content and two ternary blends containing silane‐grafted polypropylenes (PP‐VTES) of different VTES content as compatibilizer were produced. The blends were analyzed by melting flow rate, rotational rheometry, scanning electron microscopy, and differential scanning calorimetry (DSC). In all blends, the SMB_PP remained as dispersed phase in the continuous PP matrix. The addition of PP‐VTES reduced significantly the size of the SMB_PP domains. Rheological and morphological data strongly indicate that the PP‐VTES acts only by lowering the interfacial tension of the system without generating strong interaction between SMB_PP domains and the PP matrix. The dimensions of the SMB_PP domains and the interfacial energy were observed to determine the characteristics of the pseudoplastic behavior of the blends in the melt state. For both binary and ternary blends, the SMB_PP domains showed nucleating effect leading to an increase of the degree of crystallinity. However, the decrease in the interfacial energy and viscosity promoted by the addition of PP‐VTES to the system led to a more intense nucleating effect and to an increase of crystallization, melting temperatures, and melting enthalpy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 226–233, 2007     

Synergistic effects of hydroxy silicone oil on intumescent flame retardant polypropylene system

The effects of hydroxy silicone oil as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene composites (IFR-PP) were studied, and the IFR system mainly consisted of the ammonium polyphosphate (APP), melamine (MEL) and pentaerythritol (PER). The UL 94 rating, thermogravimetric analysis (TGA), cone calorimeter (CONE) and digital photograph were used to evaluate the synergistic effects of hydroxy silicone oil (HSO). It has been found that the PP composite containing only APP, MEL and PER does not show good flame retardancy at 30% additive level. The cone calorimeter results show that the heat release rate, mass loss rate, mass, total heat release, carbon monoxide and carbon dioxide of PP/APP/MEL/PER/HSO composites decrease in comparison with the PP/APP/MEL/PER composite. The digital photographs demonstrated that HSO could promote to form the homogenous and compact intumescent char layer. Thus, a suitable amount of HSO plays a synergistic effect in the flame retardancy.     

Preparation and properties of addition curable silicone resins with excellent dielectric properties and thermal resistance

A new addition curable silicone resin (ASiR) system with excellent dielectric and thermal properties was developed, which consists of only two components: poly(methylphenylvinylsiloxane) (PMPVSi) and an end‐capped hydrogen‐functionalized hyperbranched polysiloxane (EHFHPSi). PMPVSi is synthesized by a green and controllable process; EHFHPSi is first synthesized via A₂ + B₃ approach, and then end‐capped by hexamethyldisiloxane (HMDS). Three formulations were designed to investigate the optimum stoichiometry. Results show that cured ASiR resins have greatly different dielectric and thermal properties because of the different chemical structure of cured networks resulting from the different stoichiometries. The resin with a suitable stoichiometry has not only excellent dielectric properties including extremely low dielectric constant (2.96 at 1 Hz) and loss (0.0003 at 1 Hz) as well as good stability on frequency, but also outstanding thermal resistance, exhibiting great potential to be used as a new kind of high‐performance resins for many cutting‐edge industries, especially the microelectronic and insulation fields. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Improving properties of ceramic silicone rubber composites using high vinyl silicone oil

Reactive high vinyl silicone oil (HVSO) was selected to prepare the ceramic silicone rubber composites. The effects of HVSO on the mechanical properties and thermal stabilities of ceramic silicone rubber composites were investigated. The structures of the cross‐linked network of silicone rubber with or without HVSO were studied. The intermolecular space of silicone rubber was enlarged, and the cross‐linked point was concentrated by addition of HVSO, which was demonstrated by cross‐linking densities, scanning electron microscope (SEM) images, and dynamic mechanical analysis (DMA). The cross‐linked network model was formed with the slipping of the cross‐linked points along with the silicone rubber chain. Mechanical properties of composites were enhanced by the formation of this cross‐linked network. The tear strength, tensile strength, and elongation at break of the composites were increased by 18.5%, 13.2%, and 37.4% by the adding of 2 phr HVSO, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41864.     

硅油和白炭黑比表面积对硅橡胶性能的影响

气相法白炭黑是硅橡胶补强的最佳填料,羟基硅油是硅橡胶补强中常用的1种结构控制剂。本文研究了羟基硅油的用量以及气相法白炭黑比表面积对硅橡胶力学性能的影响。结果表明:随着羟基硅油用量的增加,硅橡胶的硬度、拉伸强度均逐渐降低,而断裂伸长率却随羟基硅油用量的增加而逐渐增大;随着气相法白炭黑比表面积的增大,硅橡胶的硬度、拉伸强度逐渐增大,而断裂伸长率逐渐减小。     

加成型液体乙烯基硅橡胶的研制Ⅰ.乙烯基硅油等对物理机械性能的影响

考察了乙烯基硅油及含氢硅油对加成型液体乙烯基硅橡胶物理机械性能的影响。结果表明，在100份乙烯基硅橡胶中加入10份乙烯基质量分数为10％的硅油，4.6份含氢硅油，用20份经表面处理的白炭黑增强，可得到拉伸强度为3.8MPa，撕裂强度为7.6kN/m，扯断伸长率为162％的乙烯基硅橡胶。     

Physical properties of polypropylene composites with hydrophobized cellulose powder by soybean oil

Cellulose materials have attracted lots of interest as potential natural fillers in the production of green polymer composites because they are ecofriendly and economic. In this study, to improve the interfacial bonding strength between cellulose powder and a hydrophobic polypropylene (PP) matrix, the surface hydrophobization of cellulose powder by soybean oil was carried out via a simple transesterification reaction procedure. Weight change measurements, Fourier transform infrared spectroscopy, and compatibility testing were used to quantitatively and qualitatively analyze the hydrophobization of the cellulose powder. By changing the hydrophobization conditions, the soybean oil content attached to the cellulose powder changed from 8.0 to 57.8%. PP composites with 20% of each hydrophobized cellulose powder were prepared by melt blending followed by compression molding. The mechanical properties of the PP composites were investigated with a universal testing machine and an Izod impact tester. Compared to the composite with pristine cellulose powder, the PP composite with the hydrophobized cellulose powder and an attached soybean oil content of 29.6% showed largely increased impact strength (46.3%), tensile strength (47.5%), and elongation at break (27.3%) values. The scanning electron microscopy images for the fracture surfaces of the composites showed that the hydrophobization induced much stronger interfacial bonding between the PP matrix and cellulose powder. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42929.     

氨基聚醚改性硅油的合成与性能研究

以N-β-(氨乙基)-γ-氨丙基甲基二甲氧基硅烷和环氧基聚醚(醇封端)为原料,合成了氨基聚醚;以氨基聚醚和八甲基环四硅氧烷为原料合成了氨基聚醚改性硅油,对产物进行了红外图谱分析并对氨基聚醚改性硅油进行性能测试。实验结果表明,氨基聚醚改性硅油在碱性条件下不稳定,在酸性条件下较稳定;氨基聚醚改性硅油吸水性较好,氨基聚醚改性硅油10吸水性好于氨基聚醚改性硅油04。     

充油型脱醇型硅酮密封胶性能研究

研究了甲基硅油、低分子量聚丁烯、氢化烷烃油作为增塑剂用于脱醇型RTV-1硅酮胶对其性能的影响。结果表明:甲基硅油增塑剂对降低模量、提高位移能力效果明显;聚丁烯与聚硅氧烷相容性差,影响与基材的界面粘接;少量添加烷烃油能起到与甲基硅油类似的效果,但热失重超过10%,添加量增加对基材的粘结性变差,其它性能也大幅降低。     

Mechanical properties of polypropylene composite reinforced with oil palm empty fruit bunch pulp

In this study, oil palm empty fruit bunch (EFB) pulp was used as reinforcing agent in polypropylene composite. EFB pulp was prepared using soda pulping with different concentrations of sodium hydroxide (NaOH) solution. Overall, the tensile and flexural properties specifically the strength and the toughness showed improvement as the NaOH content in the treatment was increased. This was attributed to lower probability for EFB pulp to agglomerate and the production of higher aspect ratio pulp fibers. Scanning electron microscopy analysis showed evidence of the reduction in EFB bundles diameter after NaOH treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhancement of tensile properties of isotactic polypropylene spunbonded fabrics by a surface-modified silica/silicone copolymer additive

Previous work at Kimberly–Clark Corp. (R. S. Nohr and J.G. MacDonald, Kimberly–Clark Corp., unpublished results, 1990) demonstrated that the addition of an ultrafine-particle (submicron-size), surface-modified silica predispersed in an alkyl silicone to isotactic polypropylene (iPP) results in dramatic improvements in the tensile properties of fibers and spunbonded fabrics. For both fibers and spunbonded fabrics prepared with a high concentration of the low melt flow index (MFI) resin the incorporation of the additive resulted in markedly improved tensile properties. In this article it is shown that under quiescent conditions the surface-modified silica/silicone copolymer additive acts as an effective nucleating agent for iPP. This results in a reduction in the size of the crystalline entities, hence a more homogeneously distributed crystalline phase and load-bearing “tie” molecules. Indeed, scanning transmittance electron microscopy (STEM) studies show that the crystalline entities are substantially smaller at the surface and mid-radius of fibers prepared with additive containing iPP. Furthermore, the bond points of the resulting spunbonded fabrics have a dramatically increased nucleation density and smaller crystallite dimensions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1759–1772, 1997     

硅橡胶骨架油封的研制

参照国外同类产品 ,以硅橡胶为原料研制耐油和耐磨性能良好的硅橡胶骨架油封。介绍了其产品结构、胶料性能和生胶的确定过程 ,研究了配方中 2 #气相法白炭黑和硫化程度对油封耐油性能的影响及配方中固体润滑剂的用量对油封自润滑性能的影响。结果表明 ,在硅橡胶配方中填加大量白炭黑、适当延长二次硫化时间及添加大量石墨粉 ,可提高胶料在热油中体积和性能稳定性 ,改善油封的自润滑性能     

The effect of addition of high-density polyethylene on the crystallization and mechanical properties of polypropylene and glass-fiber-reinforced polypropylene

High-density polyethylene up to about 30% by weight was melt-mixed with polypropylene and short-glass-fiber-reinforced polypropylene. The presence of high-density polyethylene and glass fibers in the polypropylene matrix affects its crystallization characteristics, which were studied with the help of differential scanning calorimetry. The blend and composite samples have a large number of polypropylene domains apparently due to an abundance of surface nuclei; as a result, the tensile strength, tensile modulus, and toughness are enhanced. The temperature dependence of shear modulus and logarithmic decrement indicate that high-density polyethylene can have plasticizing effect below the glass transition temperature of polypropylene. The scanning electron micrographs of fractured ends show the presence of dispersed domains in the composite samples.     

羟基硅油对聚氨酯热熔胶性能的影响

以聚己二酸丁二醇酯(PBA)、羟基硅油(PDMS)和4,4′-二苯甲烷二异氰酸酯(MDI)为主要原料,合成了有机硅改性的PU-HMA(聚氨酯热熔胶)。研究结果表明:PDMS明显改善了PU-HMA的疏水性,并且随着PDMS比例的增加,PU-HMA的耐热性得到改善,粘接强度呈下降趋势;当n(PBA)∶n(PDMS)=6∶1时,PU-HMA的表面水接触角提高了约15°、熔点提高了19℃且粘接强度(2.98 MPa)降幅不大。     

无溶剂加成型有机硅耐高温树脂的合成及耐热性能研究

以甲基三乙氧基硅烷、二甲基二乙氧基硅烷、苯基三乙氧基硅烷、乙烯基三乙氧基硅烷为原料,在适量的无水乙醇和水组成的混合溶剂中,通过共水解、缩聚的方法合成了性能优异的无溶剂加成型有机硅耐高温树脂,并用自制的活性稀释剂乙烯基硅油调节固含量,优化了工艺条件,控制有机基团与硅原子的物质的量比和苯基基团与有机基团的物质的量比分别为1.3和0.4,当水解温度为50℃,反应时间为3 h时可合成出综合性能优异的有机硅树脂。采用热重分析表征了硅树脂的耐热性能,结果表明:无溶剂甲基苯基硅树脂在N2气氛下的热失重主要是由主链降解引起的,当温度达到350℃时热失重仅为2.4%,具有优异的热稳定性。