苯并噁嗪/蒙脱土复合材料的制备及其性能研究

以有机MMT(蒙脱土)和苯并噁嗪(BZ)为主要原料,采用溶液插层法制备BZ/MMT复合材料。研究了有机MMT含量对BZ/MMT复合材料的热性能和力学性能等影响。结果表明:在其他条件保持不变的前提下,随着有机MMT含量的不断增加,复合材料的固化焓降低,热稳定性有所下降,拉伸强度呈先升后降态势;当w(有机MMT)=4%(相对于复合材料质量而言)时,复合材料的拉伸强度(1.6 MPa)相对最大,并且比纯BZ体系提高了20倍。     

Ultrasound‐assisted synthesis of benzoxazine monomers: thermal and mechanical properties of polybenzoxazines

A series of benzoxazine monomers (P‐aea2–P‐aea8) were prepared from appropriate aromatic diamines containing linear aliphatic ether chains with phenol and formaldehyde through the Mannich reaction under ultrasonication and conventional methods. Based on the reaction performance, the ultrasonication method has been found to be more facile and convenient for the synthesis of benzoxazine monomer than the conventional method. The synthesized monomers undergo curing at a lower temperature than that of conventional benzoxazine (Ba‐A) monomer as evidenced from differential scanning calorimetric analysis. The presence of an aliphatic ether core in the benzoxazine monomer aids in lowering the curing temperature, which seems to vary linearly with chain length. Thermally polymerized benzoxazine (poly(P‐aea_s)) shows an enhanced tensile and flexural strength. Copyright © 2012 Society of Chemical Industry     

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene: Synthesis, properties of the monomers and polybenzoxazines

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene (CP) cores have been synthesized. Theses monomers possessed controllable number of organic benzoxazine moieties and biphenyl groups distributed on the inorganic ring of CP. Corresponding ring-opening polymerization under heat led to highly cross-linked polymers with different number of crosslinking sites. The ring-opening polymerization behaviors of the new benzoxazine monomers were investigated by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). The results indicated that the polymerization activity of the monomers depended on the number of benzoxazine moiety of corresponding monomers. Those monomers with more benzoxazine moieties resulted in higher polymerization rate. Due to the high crosslinking nature with rigid and stable inorganic CP ring and biphenyl groups in the networks, the resulted polybenzoxazines from the monomers showed excellent thermal stability, mechanic property and humidity resistance.     

The influence of exchangeable aluminium ion concentration and of layer charge on the catalytic activity of montmorillonite clays

We thank the Science and Engineering Research Council and BP plc for their support.     

基于溶剂极性的双环戊二烯氢甲酰化反应探索研究

以三苯基膦改性的铁磁性氧化物担载的钴铑双金属为催化剂,考察了不同极性溶剂对双环戊二烯（DCPD）氢甲酰化反应合成三环癸烷不饱和单醛和三环癸烷二甲醛的影响。结果表明,溶剂的极性对反应速率和目标产物的选择性有较大的影响,三环癸烷不饱和单醛的生成速率随着溶剂极性的增加呈现增加的趋势;三环癸烷二甲醛的反应速率和选择性随着溶剂极性的增加先增加后降低。以极性值为5.4的丙酮作为溶剂时,合成三环癸烷二甲醛最佳,选择性达到了72%。     

Effects of solvent polarity on the hydrogenation of xylose

The three‐phase hydrogenation of xylose to xylitol and anomeric equilibria of xylose were studied batchwise in aqueous and alcoholic solvents. Rate equations based on a novel model for semi‐competitive adsorption of dissociated hydrogen and organic species were developed. The proposed kinetic model was well able to predict the xylose, xylitol and also the by‐product concentrations. The model parameters were related to the polarity of the solvent. The sugar equilibria studies gave new information about the temperature dependence of the α–β‐pyranose and pyranose–furanose equilibria of xylose, in both water and aqueous ethanol solutions. It was found that the equilibria in both D₂O and C₂D₅OD follow an S‐shaped curve, the equilibria being shifted towards the α‐form at higher temperatures. The enhancing effect of alcoholic (eg ethanol, 2‐propanol) solvents on the hydrogenation of sugars is notable. We propose that the rate accelerating effect of alcohols is mainly due to the improved hydrogen solubility. Thus, the mass transfer of hydrogen from the gas phase to the liquid bulk, and further to the surface of the catalyst is clearly improved by the use of an alcohol solvent. © 2001 Society of Chemical Industry     

Preparation of nanocomposites of thermosetting resin from benzoxazine and bisoxazoline with montmorillonite

The thermosetting resin from 2,2′‐(1,3‐phenylene)‐bis(4,5‐dihydro‐oxazoles) (PBO) and bis(3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine)isopropane (BZ) was prepared, and it was found that the thermal property of the final resin was affected greatly by the content of PBO. The nanocomposite from the thermosetting resin from BZ and PBO (molar ratio of PBO to BZ, 0.8 : 1) (PBZ–PBO) and organically modified montmorillonite (OMMT) was prepared by melt method. Differential scanning calorimetry showed that on the introduction of OMMT, the onset curing temperature of the copolymerization of BZ and PBO decreased. The X‐ray diffractometer and transmission electron micrograph characterization of the dispersion of OMMT in the PBZ–PBO matrix suggested that exfoliation structure of OMMT was achieved. Dynamic mechanical analyses indicated that the nanocomposites exhibited much higher T_g values than the PBZ–PBO resin and pristine polybenzoxazine, and storage modulus of the nanocomposites was maintained up to higher temperature with the increasing OMMT content. Dynamic thermogravimetric analysis showed that the dispersion of clay nanolayers in the PBZ–PBO copolymer gave better thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4741–4747, 2006     

The effect of the solvent on the morphology of cellulose acetate/montmorillonite nanocomposites

Nanocomposites of cellulose acetate and sodium montmorillonite were prepared using the solution intercalation method with different solvents. The effects of solvent type on the morphology, thermal and mechanical properties of the nanocomposites were investigated by X-ray microtomography and diffraction, field emission scanning electron microscopy, analytical transmission electron microscopy based on electron loss spectroscopy imaging and dynamical mechanical analysis. XRD and TEM results indicated that the dispersion and delamination of the clay are achieved when the solvent presents favorable interactions with the clay. In this case, the storage modulus and the glass transition temperature are significantly higher than those of pure cellulose acetate. The results show that the solvent has a major effect in controlling the morphology of cellulose acetate and cellulose acetate nanocomposite and could be used as a process parameter to produce films with a range of properties.     

Preparation of novel benzoxazine monomers containing ferrocene moiety and properties of polybenzoxazines

Novel benzoxazine monomers containing ferrocene were prepared, one monomer was monofunctional benzoxazine ferrocenylmethyl-3,4-dihydro-2H-1,3-benzoxazine (pC-fcma), and the other was bifunctional benzoxazine, bis(ferrocenylmethyl-3,4-dihydro-2H-1,3-benzoxazinyl)isoprapane (BA-fcma). Followed by thermal cure of monomers, metallopolybenzoxazines with ferrocene moiety in the polymer networks were obtained. The chemical structures of the novel monomers were confirmed by IR, ¹H NMR and elemental analysis. The cure behaviors of the monomers, pC-fcma and BA-fcma were studied by DSC. The thermograms of BA-fcma showed multiple peaks, which were resulted from the quickly forming network and the bulkiness factor of ferrocene moiety. In addition, the first peak temperature was much decreased by nearly 70°°C than that of typical B-a benzoxazine, which was mainly due to the electron-donating effect of N-ferrocen group stability of zwitterionic intermediates. TGA suggested that thermal stability of metallopolybenzoxazines was improved, in particular, the weight loss temperature of 5% for polyBA-fcma was increased by almost 100 °C than that of PB-a, and the char yield even reached 60% at 800 °C under N₂. Cyclic voltammetry studies of pC-fcma and BA-fcma showed that the species underwent one reversible and one-electron redox coupling.     

Synthesis of itaconimide/nadimide-functionalized benzoxazine monomers: Structural and thermal characterization

A novel series of itaconimide/nadimide-functionalized benzoxazine monomers (I-Bz/N-Bz) from imide-terminated amines, paraformaldehyde and phenol/m-cresol/cardanol/4-(hydroxyphenyl) benzoxazole were synthesized and characterized by FT-IR, ¹H and ¹³C NMR and HRMS analyses. The I-Bzs exhibited lower curing temperatures compared to the N-Bzs, which may be attributable to the presence of the 1,1-disubstituted double bond in itaconimide. The poly(I-Bz)s exhibited higher glass-transition temperatures (210–216 °C) compared to the poly(N-Bz)s (151–178 °C). The itaconimide- and nadimide-functionalized benzoxazines showed comparable thermal stability, but differences in their phenolic structures affected their thermal behavior (char yield and T_max). The poly(I-Bz)s (19–47%) showed higher char yields compared to the poly(N-Bz)s (18–41%), depending on the backbone structure. The highest lap-shear strength at 200 °C was observed in I-Bz/N-Bz derived from m-cresol.     

The irradiation of vinyl monomers in the presence of paraffin waxes

The radiation-induced grafting of a series of monomers onto a wide range of paraffin waxes was attempted. Although no grafting could be achieved and only homopolymers were formed, the rates of homopolymerization were greatly enhanced in the presence of the wax. This phenomenon is ascribed to processes of energy transfer from the irradiated wax to the monomer.     

Effect of light and solvent polarity on the preparation of polyisobutylene and of the copolymer of isobutylene with isoprene in the presence of VCI4

The polymerization of isobutylene and the copolymerization of isobutylene with isoprene, in the presence of VCI₄ in heptane and methyl chloride, were investigated in the temperature range from 253–195K in the dark and with the effect of visible light. It was found that, in the polymerization of isobutylene, the molecular mass increased linearly with decreasing temperature (log $\text{M}\text{?}{}_{\mathrm{\eta }}$ vs. $\text{1}\text{T}$). In the copolymerization of isobutylene with isoprene, it was found that the molecular mass of the copolymer increased linearly with decreasing temperature (log $\text{M}\text{?}{}_{\mathrm{\eta }}$ vs. $\text{1}\text{T}$ in methyl chloride, while in heptane there was a break in continuity near 238–233K. In the copolymerization in methyl chloride, isoprene reduced the molecular mass of the copolymer compared with that of polyisobutylene alone but, in heptane with the effect of light, isoprene increased the molecular mass of the copolymer up to twice that of polyisobutylene prepared under the same experimental conditions. If the copolymerization took place in methyl chloride, the unsaturation in mol% was equal to half the mol% content of isoprene in the initial monomeric mixture, while unsaturation of the copolymers formed in heptane solution was somewhat higher than the mol% content of isoprene in the mixture of monomers. Light had no effect on the molecular mass of polyisobutylenes and unsaturation of copolymers. VCI₄ appeared to be a highly effective initiator of the polymerization of isobutylene and of the copolymerization of isobutylene with isoprene.     

无机盐对蒙脱土结合水的影响

运用热重分析法定量分析无机盐对Na-蒙脱土和Ca-蒙脱土结合水抑制程度的定量化研究。结果表明,无机盐对蒙脱土结合水有一定抑制,由于离子结构、电荷及半径的不同,表现出不同的抑制效果,Ca Cl2的抑制能力最好,KCl因为K+的特殊结构,抑制能力较好,Na Cl的抑制能力最弱。在热失重仪定量分析结合水的基础上对Na+、K+、Ca2+影响蒙脱土结合水的机制进行了分析。     

改性泥炭对Pb(Ⅱ)和Cd(Ⅱ)的单一及竞争吸附研究

以强碱改性泥炭,研究改性泥炭对Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附效果及竞争吸附机制。结果表明,改性泥炭对Pb(2+)的吸附效果及竞争吸附机制。结果表明,改性泥炭对Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾具有显著的吸附效果,吸附容量分别由118,64 mg/g提高到225,95 mg/g;FTIR分析表明,吸附过程为Pb(2+)具有显著的吸附效果,吸附容量分别由118,64 mg/g提高到225,95 mg/g;FTIR分析表明,吸附过程为Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾与—OH、—COO-、C—H等官能团的络合作用或者离子交换作用。当吸附时间为70 min,pH在4～8,改性泥炭添加量分别为0.8,1.6 g/L时,可达到高效与经济双层效益。竞争吸附中,Pb(2+)与—OH、—COO-、C—H等官能团的络合作用或者离子交换作用。当吸附时间为70 min,pH在4～8,改性泥炭添加量分别为0.8,1.6 g/L时,可达到高效与经济双层效益。竞争吸附中,Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附容量均低于单一离子时的吸附容量,且竞争吸附能力Pb(2+)的吸附容量均低于单一离子时的吸附容量,且竞争吸附能力Pb⁽²⁺⁾>Cd(2+)>Cd⁽²⁺⁾。     

The influence of solvent type and polymer concentration on the physical properties of solid state polymerized PA66 nanofiber yarn

We investigated the effects of two different solvent types and three solution concentrations on the electrospinning of solid state polymerized polyamide 66 (SSP PA66) nanofiber yarns. Nanofiber yarns were electrospun from SSP PA66 solutions in formic acid and formic acid/chloroform (3/1), using two oppositely metallic spinnerets system. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were employed to characterize the morphology and properties of the nanofibrous yarns. Experimental results show that adding chloroform to formic acid as a binary solvent increases viscosity of polymer solution and the nanofibers diameter significantly. XRD patterns reveal that the presence of chloroform affects the crystallinity and the mechanical properties of the produced nanofibrous yarns. PA66 nanofiber yarn from 10 wt % formic acid/chloroform (3/1) solution was successfully electrospun with strength and modulus of 120.16 MPa and 1216.27 MPa respectively. It is also shown that the solution concentration has a significant effect on the modulus of the nanofibers yarns. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

苯并恶嗪的不同合成法及其表征

本文以苯胺、甲醛和双酚A为原料,分别采用溶剂法、熔融法和悬浮法合成了苯并恶嗪,并采用红外光谱对其结构进行了分析.