Organosoluble semi-alicyclic polyimides derived from 3,4-dicarboxy-1,2,3,4-tetrahydro-6-tert-butyl-1-naphthalene succinic dianhydride and aromatic diamines: Synthesis,characterization and thermal degradation investigation

Semi-alicyclic polyimides (PI-1–PI-4) have been prepared from a newly-developed alicyclic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-6-tert-butyl-1-naphthalene succinic dianhydride (TTDA) and various aromatic diamines. The asymmetrical alicyclic tetralin structure in TTDA endowed the derived PI resins good solubility in various organic solvents. They were soluble not only in polar aprotic solvents but also in solvents with low boiling points including dichloromethane and tetrahydrofuran. Flexible and tough PI films were successfully cast from their N-methyl-2-pyrrolidone (NMP) solution except PI-1 derived from TTDA and 4,4′-oxydianiline (ODA). The PI films exhibited good optical transparency in the ultraviolet and visible light region with optical transmittances around 80% at a wavelength of 400 nm. The PI films showed good thermal stability up to 400 °C in nitrogen, after that they thermally decomposed rapidly. The thermal degradation behaviors of the PIs were investigated by means of thermogravimetric analysis-mass spectrometry (TG-MS), thermogravimetric analysis-Fourier transform infrared spectrometry (TG-FTIR) and the real time FTIR spectra (RT-FTIR) analysis techniques. The results revealed that the decomposition of PI-1 (as a representative) took place mainly in the range of 450–550 °C. The major degradative fragments at 500 °C were clearly identified as the tert-butyl-substituted tetralin moiety and its dealkylation products. Therefore, it can be deduced that for the TTDA-PIs, the single bond bridge attached the maleic anhydride and tetralin anhydride units in TTDA moiety might break first during the heating; thus producing the tetralin fragments.     

Synthesis and properties of a novel hyperbranched polyphosphoramidate using an A2 + CB2 approach

The synthesis of hyperbranched polyphosphoramidate (HPPAE) has been successfully achieved via a facial A₂ + CB₂ approach. First, an AB₂ type intermediate is generated by the reaction between the phosphorus chloride group of ethyldichlorophosphate and the secondary amine group of diethanolamine. Second, the above intermediate can further self‐condense to produce the hyperbranched polymer. The molecular weight and the structural characterization of HPPAE were checked by gel permeation chromatography and Fourier transform infrared and NMR (¹³C and ³¹P) spectroscopy. The degradation study of HPPAE indicated that phosphate and phosphoramide bonds between the branch points are responsible for its complete hydrolysis in an aqueous phosphate buffer (pH 7.4) after 6 days. In addition, HPPAE presents a strong fluorescence peak at 450 nm, exhibiting the potential to track drug transport and distribution in real time. © 2012 Society of Chemical Industry     

Study on Shear Test of New Style Automotive Structural Adhesive using Digital Image Correlation Method

In this paper, digital image correlation method (DICM) is employed to measure the shear behavior of the spot welding specimens and the ones using adhesive under quasi-static lap shear testing. The images of the specimens' surfaces are captured in real-time by CCD and corresponding computer system. DICM is subsequently used to obtained strain by correlating the images captured before and after deformation. Then, both force-displacement curves and stress-strain curves of the specimens including the cracking load are obtained. The results and analysis show that the mechanical properties of specimens using adhesive compared with the spot welding specimens have an obvious advantage. This paper provides some experimental basis for improving this new type of structural adhesive. In this experiment, the method of non-contact measurement was used to obtain the strain. It has greater significance.     

宝钢1550mm冷轧生产线新技术介绍

介绍了宝钢三期工程１５５０ｍｍ冷轧生产线的概况,并分别介绍了酸洗－－连轧、连续退火、连续热镀锌、连续电镀锌、电工钢连续退火涂层等主要生产机组采用的先进技术和主要技术参数。     

Luminescence properties of the Langmuir-Blodgett film of terbium(III) stearoylanthranilate

Terbium(III) stearoylanthranilate has been prepared as a high property Z-type Langmuir-Blodgett (LB) film on various substrates by a vertical transfer process. The UV-visible absorption spectra and the low angle X-ray diffraction peaks have been collected in order to investigate the molecular arrangement and aggregation in the LB films. The average molecular orientation in multilayer stacking was determined by Attenuated Total Reflection Spectroscopy. The influence of the chemical environment of terbium within the LB films on the luminescence properties has been discussed.     

Acid-catalyzed moisture-curing polyurea/polysiloxane ceramer coatings

The para-toluene sulfonic acid (p-TSA) was used to catalyze the moisture curing of an organic/inorganic hybrid coating system. The organic phase was based on the isocyanurate of 1,6-hexamethylene of diisocyanate (HDI). The inorganic phase was based on the prepolymerized oligomers of tetraethyl orthosilicate (TEOS). An alkoxysilane-functionalized HDI isocyanate was added into the coating formulation to aid in phase miscibility. The general coating and tensile properties were evaluated as a function of the acid catalyst concentration. In addition, the films were analyzed using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The results indicated that the acid catalyst enhanced the adhesive properties of the hybrid coatings. The addition of the acid catalyst increased the changed crosslink density of films and decreased the crystallinity of the organic phase.     

Selective Adsorption of Adenosine and Guanosine by a β‐Cyclodextrin/Layered Double Hydroxide Intercalation Compound

A film of carboxymethyl‐β‐cyclodextrin‐intercalated Zn–Al layered double hydroxide (CMCD–LDH) was investigated for selective adsorption of the nucleosides adenosine (A) and guanosine (G). The effects of pH value and adsorption time on the adsorption behavior were studied. The CMCD–LDH film shows a higher selectivity for G than A under identical conditions of G and A, which results from the ability of selective recognition of the interlayer CMCD. The kinetic studies show that adsorption of A and G by the CMCD–LDH film can be described satisfactorily by the slab diffusion model. Both the values of diffusion coefficient (D) and adsorption capability (q_e) of G by the CMCD–LDH film are larger than those of A, demonstrating the selective adsorption of the CMCD–LDH film for nucleosides. Due to its easy preparation and manipulation, this film is expected to be successfully applied in the field of selective adsorption and separation.     

A method for the analysis of low-mass molecules by MALDI-TOF mass spectrometry

We report a novel method termed matrix suppressed laser desorption/ionization to improve the analysis of low-mass molecules by MALDI-TOF mass spectrometry. In this method, the surfactant of cetrimonium bromide (CTAB) is added to the conventional matrix of alpha-cyano-4-hydroxycinnamic acid solution to prepare the MALDI samples. During the MALDI process, the presence of CTAB could substantially or even completely suppress the matrix-related ion background. As a result, very clean mass spectra can be routinely obtained in the low-mass range. In addition, the presence of CTAB can significantly improve the mass resolution of low-mass molecules. It is seen that high-quality spectra were routinely obtained at a matrix/CTAB ratio of 1000:1. This method has been successfully used to analyze a variety of low-mass molecules.     

The improvement of thermal error modeling and compensation on machine tools by CMAC neural network

In this paper, a cerebellar model articulation controller (CMAC) neural network is proposed for thermal error modeling in machine tools. The CMAC is a systematic learning algorithm which can search for the nonlinear and interaction characteristics between the thermal errors and temperature field on the machine tools. The CMAC is investigated in terms of accuracy in prediction, robustness to sensor placement, speed of learning, and tolerance to sensor failures. Experimental measurements of the spindle drift errors for both a horizontal machining center and a CNC turning center were performed using capacitance sensors and thermal sensors. Results show that the CMAC model has better performance than other modeling methods in robustness to sensor placement and speed of learning. This makes determination of the sensor locations easier, and reduces calibration time. In addition, a sensor failure detection algorithm is developed to provide better reliability.