Multi-walled carbon nanotubes reinforced nylon 6 composites

Multiwalled carbon nanotubes (MWNT) were functionalized with amine groups using a ‘grafting to’ technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl chloride functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl₂), and then MWNT-COCl was reacted with hexamethylenediamine to prepare MWNT-NH₂. The formation of MWNT-NH₂ was confirmed through the FTIR observation. MWNT-NH₂/nylon 6 composites with different MWNT loadings were prepared by the simple melt compounding approach. A fine dispersion of MWNTs throughout nylon 6 matrix was observed by SEM and TEM. The fractured surface of the composites showed not only a uniform dispersion of MWNTs but also a strong interfacial adhesion with the matrix, as evidenced by the presence of many broken but strongly embedded MWNTs in the matrix in the absence of debonding of MWNTs from the matrix. Incorporation of MWNTs improved the mechanical properties significantly. Higher thermal stability was obtained for the composites with better dispersed MWNTs.     

The effect of moisture content and air-drying on spontaneous combustion characteristics of two Turkish lignites

The results of an experimental study aimed at evaluating the spontaneous combustion characteristics of two Turkish lignites moistured and air-dried at varying times are discussed. The spontaneous combustion characteristics of the coals were determined using Crossing Point Methods adapted to our laboratories conditions. The content of three predominant oxygen functional groups (carboxyl, hydroxyl, and carbonyl) of untreated, moisten and air-dried coal samples were also determined with wet chemical methods. The content of oxygen functional groups in moisten coal samples do not differ significantly that of untreated coal samples, for realized in vacuum desicator to moistured of coal samples. The liability of spontaneous combustion of the two coals was reduced when moisture content increased with increase in contacted time to water vapour. The moisten coal samples was dried in laboratory during 24 and 48 h time period. The concentration of oxygen contain functional groups of drying coal samples increased with increase of contact time with air and decrease of particle size. The liability of spontaneous combustion of the air-dried coal samples increased with increase of contacted time with air and with decrease of moisture content.     

红色复合多活性基活性染料的结构与性能关系研究一、单一染料结构与颜色以及染色性能关系

以C．I．活性红240，241，261为基础设计并合成了一组合复合双活性基的红色活性染料，各只单一染料构效关系研究表明：无机性／有机性(I／O)值与其纸层析R1值呈线性关系：重氮组分上磺酸基、硫酸酯乙基矾基、乙烯砜基等吸电子基令染料最高吸收紫移；萘系重氮组分代替苯系令染料最高吸收红移：活性红240（R2)的固色率(63．96％)和K／S(9．448)最低，而以4-硫酸酯乙基砜基苯胺和6-硫酸酯乙基砜基2-萘胺-1-磺酸为重氮组分的多活性基染料（R51R1)的固色率可达78％-84％，K／S可达15以上(2％o．w．f)。并讨论了取代基对吸附率、固色率和得色深度的影响。     

含氰侧基联苯型聚芳醚醚酮酮的合成及表征

通过一种反应条件较为温和的反应新工艺,合成联苯二甲酰氯,即4,4’-二氯甲酰基联苯(BC IBP)。然后,在无水A lC l3及N-甲基吡咯烷酮(NMP)/1,2-二氯乙烷(DCE)复合溶剂的存在下,将2,6-二苯氧基苯甲腈(DPOBN)与BC IBP进行低温缩聚反应,合成了一类新型含氰侧基联苯型聚芳醚醚酮酮。用IR,DSC,TG,WAXD及元素分析等方法对其结构和性能进行了表征。结果表明,所合成的聚合物具有预期结构且为非晶态聚合物;其玻璃化转变温度(Tg)为211℃,在氮气气氛中及在空气气氛中的热分解5%的温度(Td)分别为523℃及498℃,说明其具有突出的耐高温性能;聚合物除了能在浓H2SO4,CF3COOH/CHC l3等强质子性溶剂当中溶解外,对其他的溶剂均不溶解,说明聚合物具有优异的耐化学腐蚀性能。     

活性炭孔结构和表面官能团对吸附甲醛性能影响

通过对不同比表面积和孔结构的活性炭进行甲醛吸附的研究，以重量法精确测量活性炭对甲醛气体的饱和吸附量，比较各种活性炭和改性活性炭的吸附效果。实验表明，活性炭对甲醛分子的吸附与其孔结构和表面官能团密切相关，微孔比表面积大吸附效果明显，中孔比表面积大达到吸附平衡的时间短。此外，通过对活性炭浸渍改性的研究表明，强氧化性的HNO，和H202处理的样品均有利于对甲醛分子的吸附，而氨基改性过的样品吸附效果减弱，主要原因是HNO3改性增加了活性炭表面的C=O、O-C=O等含氧官能团的量，从而改善了对甲醛的吸附效果。     

Anomalous properties of poly(γ-benzyl L-glutamate) film composed of unusual helices

Poly(γ-benzyl L-glutamate) film composed of unusual 7-residue 2-turn ( ) helices was prepared by slow casting from chloroform solution. The helical conformation was irreversibly transformed at 84°C to the normal conformation. In d.s.c. thermograms the transformation appeared as an endothermic first order transition with an enthalpy change of 3.4 cal g⁻¹. The viscoelastic and dielectric measurements indicated that the loss peak due to the side chain motion in this film was reduced to a great extent compared to the film of helices. The dielectric relaxation strength dictated that there was a motional restriction in three quarters of the side chains. By comparison to a racemic mixture of poly(γ-benzyl glutamate), these anomalous properties were attributed to the stack of terminal benzyl groups of side chains (ormed in an alternating manner between neighbouring chains). The first order transition arises from the cooperative fusion of the stack and the side chains with their benzyl groups which are restricted in thermal motion. Such stacks may be facilitated by the precise ‘knob (side chain) and hole (space between side chains)’ packing which can be attained between neighbouring helices.     

表面含羧基的磁性高分子微球的制备和表征

以共沉淀法制备的Fe3O4为磁性来源,选用丙烯酰胺、N,N′-亚甲基双(丙烯酰胺)和丙烯酸分别作为聚合单体、交联剂和功能基单体,通过反相乳液聚合,包裹制备携带羧基的磁性高分子微球。考察了Fe3O4投入量、功能基单体量、交联剂量、聚合时间和介质的变化对磁性高分子微球的形态、磁性质及表面羧基含量的影响。采用SEMI、R、721E分光光度计和化学滴定法进行表征,制备出粒径在500 nm~10μm,表面羧基携带量为1.0 mmol/g的磁性高分子微球。     

Polymers from 2,5-difluoroterephthalic acid II. Poly(arylene ether)s containing pendant benzoyl groups

Poly(arylene ether)s (9) containing pendant benzoyl groups were prepared by the aromatic substitution reaction of 2,5-difluoro-4-benzoylbenzophenone (7) with bisphenol (8) in the presence of potassium carbonate in N,N-dimethylacetamide. The polycondensation proceeded smoothly at 170°C and produced the desired poly(arylene ether)s with inherent viscosities up to 0.79 dl/g. The polymers were quite soluble in common organic solvents and can be processed into uniform films from solutions. The thermogravimetry of the polymers showed excellent thermal stability, 10% weight losses above 450°C in nitrogen atmosphere. The glass-transition temperatures of the polymers were 138–158°C.     

Surface functionalization of nanodiamond particles via atom transfer radical polymerization

Ultradispersed diamond (UDD)/polymer brushes having excellent solution dispersibilities are prepared by atom transfer radical polymerization (ATRP) using the “grafting-from” synthesis strategy. ATRP initiators, covalently attached to oxidized surface carbon atoms of UDD aggregates using esterification chemistry, initiate polymerization of methacrylate monomers to form hydrophobic UDD/poly(iso-butyl methacrylate) and UDD/poly(tert-butyl methacrylate) polymer brushes. Acid hydrolysis of a UDD/poly(tert-butyl methacrylate) polymer brush affords a hydrophilic UDD/poly(methacrylic acid) polymer brush. Based on surface area measurements and GPC data, the calculated surface density of a representative UDD/polymer brush material is ca. five polymer chains/100 nm². A wide variety of UDD/polymer brush materials having controlled dispersibility and functional group reactivity are now potentially available using this synthesis strategy.     

The effect of methods of introducing acrylic emulsions grafted with acetoacetyl groups on the properties of particleboards

The aim of this study was to investigate the effect of compounds, either spread on particles or added to the resin, which contain various numbers of acetoacetyl groups in terms of their effect on formaldehyde content and the physical and mechanical properties of particleboards glued with the urea‐formaldehyde (UF) resin. The produced particleboards were subjected to the following European Standards standard tests: internal bond, modulus of rupture, modulus of elasticity, swelling in thickness after 24 h of soaking in water, and the content of formaldehyde. Results of the study make it possible to state that both the spreading of the acrylic emulsions containing acetoacetyl groups on the particles before gluing and the adding of them to the UF resin result in a decrease of formaldehyde content and improvement of physical and mechanical properties of particleboards. Boards with better properties were obtained in the case when emulsions containing acetoacetyl groups were spread directly on the surface of particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2256–2264, 2004