Vibrational spectroscopic characterization of rigid rod polymers: 3. Microstructural changes in stressed polymers

Highly oriented poly(p-phenylene benzobisthiazole) films were stressed in a miniature hydraulic tensile tester interfaced to a fast scanning Fourier transform infra-red spectrometer. The changes in relative intensity, polarization, frequency and shape of infrared bands have been useful in the elucidation of microstructures. With the short time resolution achievable, vibrational bandshape and frequency have been shown to change at different rates when an external stress was applied.     

A study of the cyclotrimerisation and polymerisation of aryl cyanates using 13C and 15N nuclear magnetic resonance spectroscopy,fourier transform infra-red spectroscopy and differential scanning calorimetry

Summary Three aryl cyanates, together with the products of the cyclotrimerisation of the cyanates to form aryloxy-s-triazines, have been characterised by ¹³C and ¹⁵N nmr spectroscopy. A quantitative nmr technique is proposed which allows the monitoring of the conversion of both monofunctional and difunctional cyanates to the corresponding triazines. The results compare favourably with those obtained using Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC) techniques.     

Fourier transform infra-red study of uniaxially-oriented isotactic polystyrene

Fourier transform infra-red measurements have been made of the orientation in isotactic polystyrene as a function of draw ratio. Based on these results, new band assignments are made and orientation functions calculated.     

UPR凝胶时间与储存期的测定

应用傅立叶红外光谱对两步法合成的不饱和聚酯树脂（UPR）及其凝胶进行了结构表征，分析固化剂和促进剂的用量对凝胶时间的影响，测定在不同温度和不同引发剂下的凝胶时间，并预测了UPR的储存期。     

金属卟啉配合物在催化空气氧化环己烷反应中的应用

以四苯基卟啉和乙酸盐为原料,合成了4种简单过渡金属配合物,并应用紫外-可见光谱仪（UV-vis）和傅里叶变换红外光谱仪（FTIR）对所得产物进行表征,获得了同周期过渡金属卟啉配合物吸收光谱的重要信息。研究表明,通过紫外-可见及红外光谱对过渡金属卟啉配合物中心离子的价态及其在周期表中的位置进行初步判断是可行的。以空气氧化环己烷制备环己醇和环己酮为探针反应,在不加入任何溶剂或助催化剂的条件下考察了金属卟啉用量、反应温度、压力、时间等对其催化活性的影响。结果发现,锰卟啉催化活性最好,在最佳反应条件下,环己烷转化率最高可达15.37%,环己醇和环己酮的总选择性约为93.94%。     

Surface functionalities of multi-wall carbon nanotubes after UV/Ozone and TETA treatments

A carbon nanotube (CNT) surface was successfully modified using the UV/Ozone treatment and a triethylenetetramine (TETA) solution for use as the reinforcement for polymer matrix composites. These treatments along with ultra-sonication are aimed to disperse the CNTs uniformly in the resin matrix, as well as to provide the CNT surface with chemical functionalities for adhesion with epoxy resin. Fourier transform infra-red spectroscopy and X-ray photoelectron spectroscopy are performed to evaluate the changes in chemical structure and surface functional groups arising from the UV/O₃ and TETA treatments, confirming the efficiency of the processes. The practical implications of the surface functional groups for improving the interfacial adhesion in CNT-epoxy composites are discussed.     

Fourier transform infra-red studies of coal

The application of Fourier transform infra-red (FT-i.r.) spectroscopy to the elucidation of coal structure is discussed. Hydroxyl determination by a combination of acetylation and FT-i.r. for a rank range of British coal indicates that, during coalification through the bituminous range, the proportion of oxygen as hydroxyl groups increased and deoxygenation is primarily associated with the loss of carbonyl and ether groups. However, during coalification of bituminous coal to anthracite loss of oxygen is primarily associated with dehydroxylation. The use of FT-i.r. to study changes in the oxidation of a single bituminous coal, Horden, shows that the loss of aliphatic CH groups is a prominent feature at low temperatures of oxidation. Cross-linked structures only develop at higher oxidation temperatures, at which carboxylic acids are also a major product.     

The use of FTIR to investigate modifications to wool treated with sodium sulphite and cationic protein hydrolysate

Wool was treated with sodium sulphite and amphiphilic cationic protein hydrolysate mixtures for different times and temperatures. The surface chemical modifications were followed using Fourier transform infra-red spectroscopy coupled with the attenuated total internal reflectance sampling technique. The resolution of the infra-red bands in the wool spectrum was improved by differentiation to the second-order derivative. Absorbance bands in the 1300-900 cm_-1 region were observed to change as a function of both time and temperature. Bunte salt was the main product formed from cystine, and it was measured by comparing the intensity of the Bunte salt band with the intensity of the peptide band (amide 3) in the second-order derivative spectrum. It was possible to detect dehydroalanine formation and sorption of the amphiphilic cationic protein hydrolysate in the spectrum of treated wool.     

Determination of the accessibility of N---H groups of Kevlar 49 fibres by photoacoustic FTi.r. spectroscopy

Fourier transform infra-red (FTi.r.) photoacoustic spectroscopy in combination with deuterium exchange was used to determine the accessibility of the N---H groups of Kevlar 49 fibres. The spectra were corrected for the dependence of the photoacoustic signal on the frequency and the integrated intensities of the N---H and N---D stretching bands were used to calculate the fraction of accessible N---H groups. Exposure of the deuterated fibres to saturated water vapour showed a residual N---D stretching absorption, in agreement with the improved molecular packing expected after heat-treatment at high temperature.     

Linear, soluble poly(bismethylene hydroquinone), a ladder polymer: synthesis and characterization

A route to prepare a soluble linear ladder of poly(bismethylene hydroquinone) was developed. 2,3,5,6-Tetramethylol hydroquinone was reacted with hydroquinone in sulpholane with acid catalysis. Gel formation was prevented by removing the water generated during the condensation, and by preventing oxidation of the polymer during reaction. Polymers with intrinsic viscosities as high as 5.0 were obtained; viscosity depended on the mole ratio of the starting materials and the reaction conditions. Polymer structure was characterized by Fourier transform infra-red spectroscopy, nuclear magnetic resonance spectroscopy, polarizing microscopy and X-ray diffraction.     

新型改性吸附剂制备、表征及脱除单质汞的实验研究

采用KBr和KI对高岭土、沸石、膨润土和壳聚糖进行改性,利用VM3000在线测汞仪作为检测手段,在固定床台架上进行脱Hg⁰实验。采用N2吸附/脱附、X射线荧光探针(XRF)和傅里叶变换红外光谱(FTIR)等分析仪对吸附剂进行表征。分析发现改性后吸附剂的孔隙和比表面积降低;碘离子进入了膨润土的内部,碘、硫酸和壳聚糖中的氨基发生了化学反应。脱汞实验表明,与高岭土和沸石相比,膨润土因其独特结构而具有良好的脱汞效果。适量硫酸的加入可以极大地提高壳聚糖类吸附剂的脱汞效率;与溴改性吸附剂相比,碘改性吸附剂更能够大大提高吸附剂的脱汞效率;适当提高吸附温度可以提高其脱汞效率;因改性膨润土和壳聚糖不同的物理化学特性,水蒸气的加入使得它们的脱汞效率出现相反的趋势。     

Attenuated total reflectance Fourier transform infra-red studies of crystalline-amorphous content on polyethylene surfaces

Intensity ratios of the bands due to CH₂ bending and rocking normal vibrations, used as a measure of the surface crystallinity in polyethylene, are examined by attenuated total reflectance Fourier transform infra-red (ATR FT_i.r.) spectroscopy. This study shows that the ATR optical dispersions and the orientation of surface crystallites have a substantial effect on the crystallinity measurements. It appears that improper analysis of strong, overlapping i.r. bands in the ATR spectra may generate systematic errors. While the optical effects associated with ATR measurements can be accounted for and corrected by the use of the Kramers-Kronig transform and Fresnel's equation, determination of the crystallinity gradients and orientation of the crystallites requires detailed polarization studies and theoretical considerations.     

低表面能UV固化水性柔感塑料涂料的研究

将季戊四醇三丙烯酸酯（PETA）和聚二甲基硅氧烷（PDMS）引入水性聚氨酯的主链,制得硅氧烷改性的UV固化水性聚氨酯乳液,通过FTIR红外光谱对乳液的结构进行表征。将该乳液与助剂复配,制得水性塑料涂料,并对涂层的固化动力学和表面性能进行研究。与未改性的涂料相比,硅氧烷改性的UV固化水性涂料具有良好的耐水性和耐溶剂性,同时保留了优良的手感,可用作水性柔感塑料涂料。     

The effect of processing variables on microstructure of injection molded short fiber reinforced polypropylene composites

Injection molded composites of polypropylene reinforced with short glass fibers were obtained under a variety of injection molding conditions. The microstructure of the moldings was determined using a variety of experimental techniques, including optical and scanning electron microscopy, differential scanning calorimetry, Fourier transform infra-red spectroscopy, and thermogravimetry. Thus, it was possible to obtain a detailed characterization of the crystallinity, morphology, and orientation distribution in the matrix, in addition to the distribution of fibers and their orientation of the fibers in the composite. The influence of molding conditions on the above microstructural characteristics is summarized in an effort to explain the experimental observations.     

Electrical and Structural Properties of Ar+ Implanted Nylon-6 Films

The changes in the structural and electrical properties of nylon-6 films after implantation with an inert gas ion such as Ar⁺, with energy of 285keV and at different dose rates (10¹⁴ to 10¹⁷ ions cm^-2), have been investigated. The conductivity, calculated using the projected range as the thickness of the implanted layer, increases by about four to five orders of magnitude for a dose rate of 5×10¹⁵ ions cm^-2. This is the result of the formation of dangling bonds and free radicals due to implantation. The concentration of free radicals at room temperature measured using an electron spin resonance spectrometer shows that it is proportional to the dose rate up to a certain value, beyond which irradiation-induced damage sets in. The Fourier transform infra-red absorption spectra of the samples indicate certain structural changes due to ion implantation. © of SCI.     

硅溶胶/苯乙烯-丙烯酸酯共聚物无机-有机杂化水分散液的制备和表征

A stable silica sol with 3-5 nm in diameter, which can form homogeneous film without crack, was prepared and characterized. Then, the inorganic-organic hybrid aqueous dispersion composed of such a silica sol and an emulsion of styrene （St） and acrylate （Ac） copolymer was prepared and the hybrid effect between the silica sol and poly（St-co-Ac） was observed by Fourier transform infra-red （FT-IR） spectroscope. The toughness of the film prepared by this kind of hybrid aqueous dispersion was excellent, as it was enhanced appreciably by commixing with a small amount of poly（St-co-Ac） emulsion. Some amino-polysiloxane modified hybrid aqueous dispersions were also prepared and the properties of the modified dispersions and their films were investigated. The experimental results showed that the film prepared with such an amino-polysiloxane modified hybrid dispersion exhibited excellent hydrophobicity and low surface energy after heat treatment for 1.5 h, during which the formation of the graft copolymer was observed. The surface energy of this film decreases as a result of the enrichment of siloxane segments on the film surface.     

Phonon-assisted electronic transitions in phosphorus-doped n-type chemical vapor deposition diamond films

One year ago we published the first results on the electronic structure of the P-level in 1000 ppm PH₃/CH₄ doped {111}-oriented n-type diamond films, using the quasi-steady-state photocurrent technique (PC) and photothermal ionization spectroscopy (PTIS). In this work we have extended our measurements at various temperatures (4.2–77.4 K) to samples with various doping levels (100, 500 and 1000 ppm PH₃/CH₄). This allowed us to obtain more precise results for the electronic structure of the phosphorus defect in homoepitaxial n-type CVD diamond films, making use of the 155 meV LO-phonon to explain the oscillatory photoconductivity. These results are confirmed by the PTIS maxima and Fourier transform infra-red (FTIR) data. In addition we present first measurements on a 2000-ppm doped {100}-oriented sample.     

Fourier transform Raman and Fourier transform infrared spectroscopy studies of silk fibroin

The chemical and conformational structures of Bombyx mori silk were studied with the complementary techniques of Fourier transform Raman spectroscopy and Fourier transform infrared spectroscopy. The Fourier transform Raman spectrum of silk showed strong bands for the photosensitive aromatic amino acids tyrosine, tryptophan, and phenylalanine. Intensive UV/ozone irradiation reduced the Raman intensities of the amide III band and the tyrosine signals due to peptide chain scission of the silk polymer and the photochemical changes in the tyrosine residues on the silk molecules. However, the Raman spectroscopy changes for tryptophan were less clearly defined because of peak overlapping with other amino acid signals and the low concentration of tryptophan. The Fourier transform infrared (attenuated total reflectance) technique, coupled with second‐derivative spectroscopy analysis, demonstrated a decrease in the crystallinity degree and tyrosine content of UV/ozone‐irradiated silk, as indicated by changes in the Fourier transform infrared bands of amide III doublet and tyrosine signals. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1999–2004, 2005     

Synthesis of SAPO-41 and SAPO-44 and their performance as acidic catalysts in the conversion of methanol to hydrocarbons

Crystalline samples of medium-pore SAPO-41 and small-pore SAPO-44 have been prepared by respective use of diethylamine and cyclohexylamine as templates. They were characterized using X-ray powder diffraction, DTA-TGA and diffuse reflectance infra-red Fourier transform (DRIFT) spectroscopy. SAPO-44 has larger void volume and stronger framework acidity than SAPO-41. Whereas the products of methanol conversion on SAPO-41 are dominated by dimethylether, the main products on SAPO-44 are ethene and propene. Nevertheless, SAPO-44 is less active than SAPO-34 (which possesses a similar framework structure to SAPO-44) and suffers deactivation in about an hour at 450°C.     

Determination of chain branching in low density polyethylene by 13C nuclear magnetic resonance and infra-red spectroscopy

Pulsed Fourier transform ¹³C n.m.r. studies clearly demonstrate the presence of ethyl, butyl and longer chain branches in commercial low density polyethylene. The most suitable conditions for the measurement of the relative intensities of the resonance in the ¹³C spectrum, were determined using a standard linear long chain hydrocarbon. The ¹³C spectra of polyethylenes obtained using these parameters, in conjunction with a total methyl content by infra-red spectroscopy allow a quantitative measurement of the number of each branch type to be made.