Preparation of well-aligned carbon nanotubes by pyrolysis of phenolic resin in anodic alumina pores

Well-aligned carbon nanotubes (CNTs) of high quality were synthesized by pyrolysis of phenolic resin at 800 °C in anodic alumina oxide (AAO) pores under argon protection. The innocuous source materials and safe operational conditions permit this method to synthesize well-aligned CNTs in large-scale and low cost. The formation mechanism of the synthesized CNTs is also proposed in this work by a series of visual sketches and is proved with obvious evidence. Firstly, phenolic resin nanotubes form in the template pores through the evaporation of solvent. Heat treatment then transfers these tubes into CNTs.     

大孔吸附树脂对大豆皂苷的吸附研究

比较了5种大孔吸附树脂对大豆皂苷的吸附等温线、吸附容量、解吸率和吸附动力学。发现ZTC-1树脂对大豆皂苷吸附量大、解吸容易、吸附速度快，是一种良好的大豆皂苷吸附荆，AB-8树脂次之．选择ZTC-l树脂纯化大豆皂苷粗提液，得到大豆皂苷产品纯度为78．2％(干物质)，回收率为93．1％．     

Effects of petroleum resins on asphaltene aggregation and water-in-oil emulsion formation

Asphaltenes from four crude oils were fractionated by precipitation in mixtures of heptane and toluene. Solubility profiles generated in the presence of resins (1:1 mass ratio) indicated the onset of asphaltene precipitation occurred at lower toluene volume fractions (0.1–0.2) than without resins. Small-angle neutron scattering (SANS) was performed on solutions of asphaltene fractions in mixtures of heptane and toluene with added resins to determine aggregate sizes. Water-in-oil emulsions of asphaltene–resin solutions were prepared and separated by a centrifuge method to determine the vol.% water resolved. In general, the addition of resins to asphaltenes reduced the aggregate size by disrupting the π–π and polar bonding interactions between asphaltene monomers. Interaction of resins with asphaltenic aggregates rendered the aggregates less interfacially active and thus reduced emulsion stability. The smallest aggregate sizes observed and the weakest emulsion stability at high resin to asphaltene (R/A) ratios presumably corresponded to asphaltenic monomers or small oligomers strongly interacting with resin molecules. It was often observed that, in the absence of resins, the more polar or higher molecular weight asphaltenes were insoluble in solutions of heptane and toluene. The addition of resins dissolved these insolubles and aggregate size by SANS increased until the solubility limit was reached. This corresponded approximately to the point of maximum emulsion stability. Asphaltene chemistry plays a vital role in dictating emulsion stability. The most polar species typically required significantly higher resin concentrations to disrupt asphaltene interactions and completely destabilize emulsions. Aggregation and film formation are likely driven by polar heteroatom interactions, such as hydrogen bonding, which allow asphaltenes to absorb, consolidate, and form cohesive films at the oil–water interface.     

Synthesis and characterization of new epoxy and cyanate ester resins

New epoxide and cyanate ester resins with an aromatic ester backbone namely 1,3-[di-(4-glycidyloxy diphenyl-2,2^′-propane)]-isophthalate (DGDPI) and 1,4-[di-(4-cyanato diphenyl-2,2^′-propane)]-terephthalate (DCDPT) were synthesized and the intermediates were characterized by IR, 1H-/¹³C-NMR spectroscopic methods. The cured products from DGDPI and DHDPI exhibited higher T_g compared with standard epoxy system. The increase in the T_g may be due to the cyanate ester and rigid aromatic backbones present in the curing system.     

适用于RTM成型聚酰亚胺材料研究进展

综述了适用于RTM成型耐高温聚酰亚胺材料的研究进展，主要包括降冰片烯酸酐（NA）封端的PMR聚酰亚胺树脂和使用苯乙炔基封端剂合成的酰亚胺低聚物，在这其中采用苯乙炔基封端剂合成的酰亚胺低聚物具有低的熔体粘度和良好的熔体稳定性，固化交联后的聚合物及树脂基复合材料具有良好的热性能和力学性能。本文介绍了上述聚合物化学合成、结构与性能之间的关系，并对适用于RTM成型耐高温聚酰亚胺材料的应用进行了简单介绍。     

Separation and Gas Chromatographic Determination of Free Styrene in Unsaturated Polyester Resins

Abstract

A rapid and efficient method for the separation and determination of free styrene in unsaturated polyester resin samples by gas chromatography was developed. A 10 cm pre-column connected to 1.2 m analytical column, both packed with 20 % carbowax 20M was used at 100°C with isobutylbenzene as an internal standard. Analysis time was two minutes with an accuracy of 0.3 %.     

Fatty Acid Methyl Esters as Biosolvents of Epoxy Resins: A Physicochemical Study

The C8 to C18 fatty acid methyl esters (FAME) have been compared as solvents for two epoxy resin pre-polymers, bisphenol A diglycidyl ether (DGEBA) and triglycidyl p-aminophenol ether (TGPA). It was found that the solubilization limits vary according to the ester and that methyl caprylate is the best solvent of both resins. To explain these solubility performances, physical and chemical properties of FAME were studied, such as the Hansen parameters, viscosity, binary diffusion coefficient and vaporization enthalpy. Determination of the physicochemical parameters of FAME was carried out by laboratory experimentations and by calculation from bibliographic data. The Hansen parameters of FAME and epoxy resins pre-polymers were theoretically and experimentally determined. The FAME chain length showed a long dependence on the binary diffusion parameters and kinematic viscosity, which are mass and momentum transport properties. Moreover, the vaporization enthalpy of these compounds was directly correlated with the solubilization limits.     

氧瓶-离子色谱法测定树脂中的卤素和硫元素

含有卤素和硫元素的树脂样品经氧瓶法燃烧分解，用含H2O2的去离子水溶液吸收，离子色谱法分离测定．本法简便、快速，特别适于测定树脂中不活泼的卤族元素，且可同时测定。CI、S的相对标准偏差分别为0．22%,0．36％，最大绝对误差分别为0．43％和0．80％。树脂中CI、S的含量在0．28mmol/g～14mmol／g内可用此法准确测定，其最低检测限为0．05mmol／g。     

Initial Steps in Thermal Degradation of Fractions of PVC with Different Tacticities

PVC samples were prepared in bulk by using AIBN and UV radiation as the initiator system. The polymerization temperatures were 40, 0, -25, and -50oC. The samples were fractionated by means of successive extractions with dioxane, tetrahydro-furan, and cyclohexanone, and two fractions of each sample were characterized in order to study their thermal degradation. This was carried out by conductivity measurements with the use of a differential conductimetry cell for degradations up to 0.1% and a single cell for degradations up to 0.4%. From the UV-visible spectra of equally degraded samples it is concluded that the higher the tacticity of PVC, the higher the proportion of long polyene sequences is; this behavior is independent of the conversion. The degraded samples were ozonized in order to measure the number of scissions per chain. This number was found to be low for syndiotactic samples and high for atactic samples, which is accounted for by the increased clustering of double bonds to form long polyene sequences in the more syndiotactic polymers. Previous results suggesting increased ease of propagation along syndiotactic sequences are therefore confirmed more quantitatively.     

An atomic force microscopy study of asphaltenes on mica surfaces. Influence of added resins and demulsifiers

 Monolayers of asphaltene and resins on the water surface have been transferred at a surface pressure of 10 mN/m onto mica substrates using the Langmuir–Blodgett technique. Atomic force microscopy (AFM) has been used to examine the topography of these layers. Monolayers consisting of pure asphaltene fractions provide a rigid film with a close-packed structure, while the resins build up a continuous open network. Mixed films of these two fractions show that a gradual increase in resin concentration leads to an opening of the rigid asphaltene structure towards a more resin like configuration. Increased aggregation when the two heavy functions are present in one film is seen as larger individual units in the AFM pictures. Addition of high-molecular-weight demulsifiers/inhibitors results in the same kind of influence on the asphaltene film as seen with the resins. Received: 30 April 1999 Accepted: 29 November 1999