MCPA6/气相SiO_2复合材料的制备及性能研究

以氢氧化钠为催化剂,N-乙酰己内酰胺为活化剂,通过阴离子原位聚合法制备浇铸尼龙6(MCPA6)/气相Si O2复合材料,并利用扫描电子显微镜、差示扫描量热、热重分析、力学性能测试等方法研究了气相Si O2用量对复合材料的微观形态、结晶性能、吸水率、热稳定性能及拉伸和冲击性能的影响。结果表明,经硅烷偶联剂(KH550)处理的气相Si O2能均匀分布在MCPA6中;气相Si O2可促进MCPA6的结晶,降低吸水率,当气相Si O2用量为己内酰胺质量的0.5%时,复合材料的吸水率最低,比MCPA6降低16%;复合材料的热稳定性提高,当气相Si O2用量为己内酰胺质量的2.5%时,复合材料起始分解温度和失重速率最大时分解温度分别比MCPA6提高98.8℃和38℃;随着气相Si O2用量增加,复合材料的拉伸和冲击性能均呈先升高后降低的趋势,当气相Si O2用量为己内酰胺质量的0.5%时,拉伸强度、断裂伸长率及缺口冲击强度较MCPA6分别提高10%,6%和81%。     

Biodegradable Composites: Ramie Fibre Reinforced PLLA-PCL Composite Prepared by in Situ Polymerization Process

Summary  Thermoplastic biodegradable composites based on ramie fibre (RF) and a poly(l-lactic acid)-poly(ε-caprolactone) (PLLA-PCL) matrix was manufactured using the in situ polymerization method. In order to improve the compatibility and strengthen the interface in natural fibre composite materials, the RF was firstly treated by coupling agents. Then the RF reinforced thermoplastic PLLA-PCL composite was prepared by in situ polymerization of PLLA oligomer with NCO-terminated PCL prepolymer. The effect of fibre length and fibre content on tensile strength and impact strength of this natural-fibre-reinforced biodegradable composite (PLLA-PCL/RF) was discussed, including the influence of the use of silane coupling agent (KH550) for improved interfacial adhesion. The results showed that the tensile strength and impact strength of PLLA-PCL/RF were highest when the RF length was 5-6mm, RF content was 45% and with KH550 as surface treatment agent of RF.     

Molecular Self-Assembled Microcapsules Prepared by In Situ Polymerization Technology for Self-Healing Cement Materials

Monodisperse core–shell microcapsules have been widely used as self-healing cement materials and paid more attentions. A new series of self-assembled microcapsules containing poly(styrene-divinylbenzene) as shell material were prepared by in situ polymerization technology. The microencapsulating process of core material using mixture of epoxy resins and benzyl alcohol was monitored using optical microscopy (OM). Morphology and shell wall thickness of microcapsule were observed using scanning electron microscopy and OM, respectively. The effects of different weight ratios of core–shell and the agitation rates on the physical properties of microcapsules were investigated. The size and surface morphology of microcapsule can be controlled by selecting different processing parameters.     

原位聚合PE/MMT纳米复合材料的流变行为研究

采用蒙脱土(MMT)负载的Ziegler-Natta催化剂,通过原位聚合法制备了不同MMT含量的聚乙烯(PE)/MMT纳米复合材料。利用热重分析(TGA)确定了PE/MMT纳米复合材料中MMT的含量,并使用Haake流变仪分析了MMT含量对PE/MMT纳米复合材料流变行为的影响。结果表明:PE/MMT纳米复合材料的熔体流变行为与高密度聚乙烯(HDPE)和低密度聚乙烯(LDPE)基本一致;复合材料的黏度随MMT含量的增加先升高后降低,其中当MMT含量为4.58%时,其黏度明显低于HDPE和LDPE,该性质有利于复合材料的成型加工;PE/MMT纳米复合材料属于假塑性流体,其非牛顿指数(n)随着温度的升高而增大,随着MMT含量的增加先降后升。     

Highly Conductive Cellulose Network/Polyaniline Composites Prepared by Wood Fractionation and In Situ Polymerization of Aniline

Highly conductive cellulose network/polyaniline (PANI) composites are successfully formed using chemical fractionation of solid wood followed by in situ polymerization of aniline monomers in the purified wood. The increased porosity of the wood caused by the fractionation process enables the uniform deposition of PANI particles in the microstructure of the material, resulting in a high electrical conductivity of up to 36.79 S cm^?1, and a high weight gain rate of up to 143%. The interaction between PANI and the cellulose microfibril network leads to a decreased crystallinity of the composites. The electrode prepared from the cellulose network/PANI composites exhibits promising gravimetric specific capacitances of up to 218.75 F g^?1 and areal specific capacitances of up to 0.41 F cm^?2, and it can be assembled into all‐solid‐state supercapacitors with favorable energy storage performance, which may be attributed to the larger surface area, higher PANI content of the electrode, and the positive effect of the cellular structure of the cellulose network on electron transport. The present process can preserve the naturally hierarchical structure of wood and impart a promising conductivity to the composites, and it provides a promising way to produce hierarchical biomass‐based electronic materials for high‐performance storage field.     

离子液体原位插层聚合法制备蒙脱土-聚酯复合材料

选用十二烷基三苯基磷和酯季磷盐离子液体对钠基蒙脱土(Na-MMT)进行插层改性,并分别与对苯二甲酸二甲酯、乙二醇进行原位插层聚合制备MMT-聚酯(PET)复合材料,使用远红外光谱(FTIR)、广角X射线衍射(WAXD)、扫描电镜(FESEM)、透射电镜(TEM)等对MMT及MMT-PET复合材料进行表征。结果表明:MMT被成功插层,有机改性MMT在PET基体中的分散性优于NaMMT,而酯季磷盐-MMT在PET基体中有明显插层的现象。这证明了MMT插层剂的酯键可与PET进行酯交换反应,进一步说明反应性插层剂有利于制备稳定分散的MMT-PET复合材料。     

乳液聚合法制备聚苯乙烯／蒙脱土插层复合材料

利用乳液聚合法制备了聚苯乙烯／蒙脱土插层复合材料,XRD,FTIR等表明,聚苯乙烯已插层进入蒙脱土层间,TGA,DSC表明,复合材料的热稳定性提高了,其热分解温度和玻璃化转变温度的提高是由于聚苯乙烯插层进入蒙脱土层间,并和蒙脱土产生相互作用的结果,初步提出了乳液聚合插层机理。     

Intercalated PS/Na+‐MMT Nanocomposites Prepared by Ultrasonically Initiated In Situ Emulsion Polymerization

Summary: A new technique, ultrasonically initiated in situ emulsion polymerization, was employed to prepare intercalated polystyrene/Na⁺‐MMT nanocomposites. FTIR, XRD, and TEM results confirm that the hydrophobic PS can easily intercalate into the galleries of hydrophilic montmorillonite via ultrasonically initiated in situ emulsion polymerization, taking advantages of the multi‐effects of ultrasonic irradiation, such as dispersion, pulverization, activation, and initiation. Properly reducing SDS concentration is beneficial to widen the d‐spacing between clay layers. However, the Na⁺‐MMT amount has little effect on the d‐spacing of nanocomposites. The glass transition temperature of nanocomposites increased as the percentage of clay increased, although the average molecular weight of PS decreased, and the decomposition temperature of the 1obtained nanocomposites moves to higher temperature.

TEM of PS/Na⁺‐MMT nanocomposite prepared by ultrasonically initiated in situ emulsion polymerization.     

原位聚合制备聚甲基丙烯酸甲酯/石墨烯复合材料

采用原位聚合的方法,将石墨烯和甲基丙烯酸(MMA)通过超声共混后引发聚合,制备了聚甲基丙烯酸甲酯(PMMA)/石墨烯复合材料。采用原子力显微镜、透射电子显微镜、扫描电子显微镜、傅立叶变换红外光谱仪和X射线衍射仪对PMMA/石墨烯的结构和形貌进行了表征,复合材料的拉伸性能和导电率分别采用拉力试验机和四探针金属/半导体电阻率测量仪器测试。结果表明,石墨烯均匀地分散在PMMA中,加入石墨烯后,PMMA的拉伸应变弹性模量、最大拉伸应变得到了大大提高。而且,当石墨烯含量由0增加到1%时,复合材料的电导率由1×10-14 S/cm提高到了8.89×10-2 S/cm,PMMA由原来的绝缘材料改性为导电材料。     

Electroactive Polymer Blends Prepared In Situ Via Bulk Polymerization of Aniline in the Presence of Polyethylene

Abstract

The modification of polypropylene (more precisely, a propylene/ethylene random copolymer containing 10% ethylene) has been accomplished by melt grafting of acrylamide tertiary butyl sulfonic acid(ATBS) initiated with a radical initiator. The resulting PP-g-ATBS was used to prepare ternary blends of PA1O1O/PP-g-ATBS/PP and binary blends of PA1010/PP. The size of domains of PP in ternary blends is much smaller than that in binary blends. It was found that mechanical properties of ternary blends obviously surpassed that of binary blends. These behavior could be contributed to chemical interactions between sulfonic acid groups of PP-g-ATBS and end amino group of PA1010. Thermal and rheological analysis were performed to confirm the possible chemical reactions taken place during the blending process.     

Preparation of Cinnamon Oil‐Loaded Antibacterial Composite Microcapsules by In Situ Polymerization of Pickering Emulsion Templates

In this study, the cinnamon oil (CMO)‐loaded antibacterial composite microcapsules with silicon dioxide (SiO₂)/poly(melamine formaldehyde) (PMF) hybrid shells are effectively and facilely constructed by in situ polymerization of SiO₂ nanoparticle–stabilized Pickering emulsion templates. The morphological structure, composition, and thermal performance of the microcapsules are determined by scanning electronic microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. In addition, in vitro CMO release and antimicrobial investigations of the microcapsules are also performed, respectively. The results demonstrate that the microcapsules own an approximately spherical shape with a core–shell structure. Moreover, the micro‐encapsulation of CMO clearly increases its thermal stability, and meanwhile results in obtaining microcapsules with the controlled CMO release and visibly long‐term antimicrobial effects. All the results show that in situ polymerization based on templating Pickering emulsions is an attractive method to construct antibacterial essential oil–loaded microcapsules, which can be served as promising antibacterial materials.     

Antibacterial Thin Film Composite Polyamide Membranes Prepared by Sequential Interfacial Polymerization

In this work, thin film composite polyamide (PA) membranes are modified by polyethyleneimine (PEI) and 2,6‐diaminopyridine (DAP) through sequential interfacial polymerization to fabricate contact active antibacterial membranes. The modified membranes show improved hydrophilicity and enhancement of zeta potential. Upon tethering with PEI and DAP onto the PA membranes, the membrane flux increases from 35.7 to 46.7 and 50.0 L m^?2 h^?1, respectively. Further the salt rejection rate improves from 96.6% to 98.0% and 98.8%, respectively. The PA‐PEI membranes have a better antibacterial performance than PA‐DAP, with a bacteria killing ratio for both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) over 96.7%, while a commercial LC LE‐4040 membrane presents bacteria killing ratio of 13.3% for E. coli and 8.4% for S. aureus, respectively.     

原位乳液聚合法制备聚苯乙烯-丙烯酸酯/纳米蒙脱土复合乳液

通过原位乳液聚合法,采用5种不同类型的蒙脱土制备了聚苯乙烯-丙烯酸酯/蒙脱土复合乳液。讨论了各种影响因素对复合乳液制备及乳液涂膜性能的影响,采用正交实验的方法对实验工艺进行优化,并采用X射线衍射(XRD)对复合物结构进行了分析。结果表明:蒙脱土在复合物中呈现纳米级分散,形成了插层型结构。钠型蒙脱土制备出的复合乳液性能较好,蒙脱土含量增加对单体聚合有一定阻聚作用。     

原位乳液聚合法制备聚苯乙烯一丙烯酸酯／纳米蒙脱土复合乳液

通过原位乳液聚合法，采用5种不同类型的蒙脱土制备了聚苯乙烯一丙烯酸酯／蒙脱土复合乳液。讨论了各种影响因素对复合乳液制备及乳液涂膜性能的影响，采用正交实验的方法对实验工艺进行优化，并采用X射线衍射（XRD）对复合物结构进行了分析。结果表明：蒙脱土在复合物中呈现纳米级分散，形成了插层型结构。钠型蒙脱土制备出的复合乳液性能较好，蒙脱土含量增加对单体聚合有一定阻聚作用。     

Zirconium Carbide–Tungsten Cermets Prepared by In Situ Reaction Sintering

Zirconium carbide–tungsten (ZrC–W) cermets were prepared by a novel in situ reaction sintering process. Compacted stoichiometric zirconium oxide (ZrO₂) and tungsten carbide (WC) powders were heated to 2100°C, which produced cermets with 35 vol% ZrC and 65 vol% W consisting of an interpenetrating-type microstructure with a relative density of ∼95%. The cermets had an elastic modulus of 274 GPa, a fracture toughness of 8.3 MPa·m^1/2, and a flexural strength of 402 MPa. The ZrC content could be increased by adding excess ZrC or ZrO₂ and carbon to the precursors, which increased the density to >98%. The solid-state reaction between WC and ZrO₂ and W–ZrC solid solution were also studied thermodynamically and experimentally.     

有机蒙脱土对原位插层聚合PMMA性能的影响

利用原位插层聚合法在玻璃模具中合成了聚甲基丙烯酸甲酯/有机蒙脱土(PMMA/OMMT)纳米复合材料,实现了层状OMMT在PMMA基体中剥离成纳米片状OMMT。用DSC和DMA对一维纳米OMMT片层环境下PMMA链的松弛性进行了表征。DMA测试结果显示,复合材料的玻璃化转变温度比纯PMMA高,且对应峰的强度随着OMMT用量的增加而降低,表明纳米片状OMMT对其周围的PMMA链的运动具有限制作用。     

Preparation of PZT Microtubes by Slip Casting on Vermicelli,Followed by In Situ Polymerization

Slip casting of lead zirconate titanate (PZT) slurries of higher solids loading (48.8–51.6 vol%) prepared in a urea–formaldehyde (UF) monomer solution on vermicelli of ∼1000 μm diameter has been studied to prepare PZT microtubes with a higher wall thickness (200–960 μm) in a lower dipping time (0.5–4.0 min) to facilitate faster production and lower failure during drying and vermicelli burnout. Polymerization of the UF monomer by exposing the PZT slurry-coated vermicelli to HCl gas provides good strength and stability to the coating. The dielectric and piezoelectric properties of the microtubes compare well with the properties of PZT-5H ceramic compositions.     

Physico-Chemical Characterizations of Poly(vinylidene fluoride)/Cu3(BTC)2 Composite Membranes Prepared by In Situ Crystal Growth

In this work, we present a simple and fast method for elaborating hybrid membranes by growing metal–organic framework crystals inside a polymer solution. The solution thus obtained was casted then annealed at 90°C for 5 h. This method was tested with poly(vinylidene fluoride) (PVDF) as a piezoelectric polymer and the Cu₃(BTC)₂, BTC = 1,3,5-benzene tricarboxylate, as a filler. The characterization of the obtained membranes by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray diffraction showed the presence of the characteristic signatures of Cu₃(BTC)₂ and the β-phase of PVDF. Moreover, scanning electron microscopy images reveal that the Cu₃(BTC)₂ crystallites have grown along the PVDF membranes. The effect of the filler on both thermal and mechanical properties of the membranes was also studied. POLYM. ENG. SCI., 60:464–473, 2020. © 2019 Society of Plastics Engineers     

Composite Zirconium Silicides Through an In Situ Process

Zirconium silicides are being investigated for use as neutron reflector materials for the next generation of nuclear power devices. Hot isostatically pressed monolithic Zr₃Si₂ and reactive sintered Zr _X Si _Y composite are currently under development. The composite is obtained in situ and contains a ZrSi matrix embedding shell-like Zr, Zr₂Si, and ZrSi₂ domains with volume ratios depending on the initial Zr/Si ratio. Despite the lack of information on the mechanical properties of zirconium silicides, the composite structure is assumed to have enhanced fracture toughness; conditions to improve it further are discussed on the basis of microstructural observations of crack deflection.