Key Engineering Materials Vols. 575-576

Abstract: Shape memory polymer (SMP), which has attracted lots of attentions recently, is a kind of smart material. The thermally induced SMPs can remember two different shapes because of the combined functions of polymers molecular architecture, morphology and the specific multi-step processing technology named shape memory creation programming. This paper aims to analyze Polyurethanes shape memory properties based on the viscoelastic theory. First, the Polyurethanes creep and relaxation performances are simulated using Maxwell-Weichert model. The simulated results of relaxation process are found in good agreement with the experimental results. Later, same model is used to describe Polyurethanes shape memory effects in strain-controlled situation. As the results show, Polyurethanes shape recovery ratios are almost 100%, whereas shape fixing properties are relatively poor. Moreover, as shown by the simulated results of recovery time under different recovery temperatures, recovery time shortens along with the increase of recovery temperature.

Abstract: As an outstanding class in smart materials of particular interest, shape memory polymers (SMPs) and their composites are drawing more and more attentions due to their potential applications in fields like biomedical and spacecraft industry. In this paper, shape memory behaviors of polyurethane (PU) in stress-controlled situations are simulated on the basis of the generalized Maxwell model and the time-temperature superposition principle. The free recovery cycles under three different imposed stresses and the influence on shape memory behaviors caused by changing heating rate are discussed. As the results reveal, the generalized Maxwell model can be used to describe the PU shape memory performance, and the shape recovery temperature increases with the increase of heating rate.

Abstract: Driven by the urgent demand for novel electrochemiluminescence reagents, a water-soluble polyfluorene derivative, poly [(9,9-bis (3-((N,N-dimethylamino)N-ethy-lammonium) propyl)-2,7-fluorene)-alt-2,7-(9,9-p-divinylbenzene)] dibromide (P-2), was designed and success-fully synthesized. Ultraviolet-visible spectroscopy and fluorescence spectroscopy were used to characterize the formation of P-2, and the results showed that P-2 had strong fluorescence intensity. More importantly, electrochemiluminescence (ECL) of the prepared P-2 was also observed when the applied potential was cycled between 1.0 to 2.8 V at 100 mV·s^-1 in phosphate buffered saline buffer solution (pH 8.20). Based on the stable ECL performance, an ECL system for bovine serum albumin (BSA) was constructed. Under the optimal conditions, the enhanced ECL intensity was linearly correlated to the concentration of BSA over the range of 5.0×10^-8-1×10^-4 g·mL^-1 (R=0.9996) with a detection limit of 1.26×10^-8 g·mL^-1 (n=11). This work not only introduced a substitute for traditional ECL regents, but also proposed a simple ECL system for other analytes.

Abstract: The compositions of PVC slush powder are determined by means of gel permeation chromatography (GPC) and pyrolysis gas chromatography/mass spectrometry (PGC-MS) methods after its separation and purification. The melt and combination of the powder during the formation processes of the slush molded skins are observed by polarizing microscope experiments. Dynamic mechanical analysis (DMA), stress relaxation experiments and Haward model are then used to study the physical and mechanical properties of the skin. It is found that the powder contains abundant phthalate and trimellitate plasticizers because of which the glass transition temperature T_g of the skin is quite low. There is a critical temperature above which the melt and combination of the powder accelerate. Stress relaxation experiments can eliminate the interference of viscous force. Based on that, the network structure of the skin and its Gaussian modulus can be well represented by Haward model.

Abstract: It is one of large copper mine which discoveried newly in the middle of arc-magma-metallogenic belt in Xiongcun Cu (Au) deposits, Xietongmen county, Tibet. In order to analyze deposits model, the methods adopted includes that arrangement of existing geophysical and geochemical exploration results, familiar with the former research results, and based on the collection of data, studying comprehensively the geological characteristics of deposits, discussing the deposits genesis. It found that metal mineral combination about the Cu (Au) ore body is pyrite + chalcopyrite + molybdenite (less) + magnetite (less), and transit to a peripheral area of pyrite + chalcopyrite + magnetite, to sphalerite + chalcopyrite + pyrite + lead ore (less) from inside to outside in porphyries body in Xiongcun by studying, which reflected the rock permeability and diffusion about the hydrothermal system of ore-bearing porphyry, all this caused by different types of mineralization process due to temperature and pressure reduction. Elements in the vertical direction with zoning characteristics, that is Cu, Au, Ag, As, Sb, (Bi) - Co, Ni - Mo - Mn - Ba - Pb, Zn, Cd, Bi, (Sb) from the center to outward. The elements anomalies and combination is the important geochemical markers to find and evaluate this kind of deposits. Xiongcun Cu (Au) deposits belong to low-grade porphyry type Cu (Au) deposits which related to emplaced hornblende quartz diorite late Jurassic, and is series of island arc type porphyry copper metallogenic of the Gangdese terrane subduction. Deficiency is a lack of data, it is very difficult to distinguish which kind of exploration method played a key role, the division includes both the exploration methods and working train of thought, prospecting cognition. One deposits is likely to belong to this category, and may belong to the other because of the mutual cross.

Abstract: DABCO (1, 4-diazabicyclo [2.2.2] octane) has been used in combination with pentameric zinc porphyrin-pyrene array 1 to form well-defined supramolecular arrays through axial coordination. The self-assembly process has been investigated by a wide range of spectroscopic methods including UV-vis, fluorescence emission and ¹H NMR techniques.

Abstract: Using gelatin as dispersant, liquid paraffin as porogen, novel hypercrosslinked polymeric adsorbents of LM-5 and LM-6 were prepared by post-crosslinking reaction with phenol and 2-naphthol, respectively. Bromoethane was used as crosslinking reagent to substitute poisonous organic compound of chloromethyl methylether. 2-Naphthol was used in the post-crosslinking reaction to enhance phenolic hydroxyl group content. The experiments of selective adsorbing aniline on resins in mixture solution, which consisting of benzene and aniline, show that the adsorption of aniline and benzene on LM-6 in aqueous solution are mainly pushed by physical interaction. The adsorption of aniline is also partly pushed by chemical interaction, and the adsorptive enthalpy illuminates that there exists hydrogen-bonding. Owning to the hydrogen-bond, the adsorption capacity of aniline on LM-6 is markedly higher than that of benzene.

Abstract: This paper reviewed the current situation and process of research on in-situ metal matrix composites. Compounding mechanisms, fabricating techniques and main features of metal matrix composites were respectively analyzed. At the same time, the properties of different kinds of in-situ metal matrix composites were briefly introduced. Meanwhile, the problems in the in-situ fabricating techniques and future prospects were also discussed.

Abstract: NiCoCrAlY/AT13 composite coating was prepared by plasma spraying technology on AZ91D substrate and sealed with three different methods. The corrosion resistances of the composite ceramic coatings with and without sealing were evaluated by immersion and electrochemical tests The results show that NiCoCrAlY/AT13 composite ceramic coating represents better corrosion property than single AT13 ceramic coating. The corrosion resistances of NiCoCrAlY/AT13 composite coatings with sealing are superior to that of unsealing coating. Among three sealed coatings, both coatings sealed with paraffin and varnish exhibit better corrosion resistance with corrosion rate of 0.130 g/(m²·h), 0.204 g/(m²·h), and I_corr of 1.754E-7 (A·cm^-2), 9.493E-8 (A·cm^-2) respectively, while the coating with epoxy resin sealing is relatively the worst one with corrosion rate of 0.744 g/(m²·h) and I_corr of 1.650E-7 (A·cm^-2).

Abstract: The paper describes a novel capillary reinforced plastic which can self-repair the impact damage in polymer composites through employing a bio-mimetic approach. A epoxy resin E-51 and harder WSR706^# was used as the healing agent, the two components being filled in to different directions (0°and 90° fibers). Impact test and tensile test were used as a measure of the self-healing effectiveness. The results of flexural testing have shown that strength lost after impact damage can be restored by the self-healing effect with healing agent stored in capillaries, and a significant fraction (about 79%) of lost mechanical strength is restored by this effect. At the same time, the paper also studied the morphology of fracture surface of no embedded and capillaries embedded sample. And micrographs of crack morphology which has been healed have been observed.