Advanced Materials Research Vols. 87-88

Abstract: Interactions of polymer and solvent in a highly chemical crosslinked polystyrene (PS) and polymethyl acrylate (PMA) gels are investigated. Crystal thermo of the benzene in PS-benzene gels were analyzed using differential scanning calorimeter (DSC). It was noted that benzene molecules in the gels can be categorized into three types, which is free benzene, weak bonded benzene and strong bonded benzene. In average, one PS structure unit interacted with three benzene molecules in the gel system. The conformation of dichloroethane (DCE) in PMA-DCE gels was studied using Fourier transfer infrared (FTIR). In PMA-DCE gels, DCE molecule bonded with PMA chains in a trans mode through a hydrogen bond. And the amount of trans DCE molecules increased with the increase in concentration of PMA in the gel system.

Abstract: Photo- and temperature-responsive amphiphilic block copolymers, poly(ethylene glycol)-b-poly{(N-isopropylacrylamide-co-6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate), denoed as PEO-b-P(NIPAM-co-MAZO), were designed and synthesized by atom transfer radical polymerization (ATRP). The macroinitiator based on poly(ethylene glycol) (PEG, Mn = 2000 Da) was utilized to initiate the copolymerization of N-isopropylacrylamide (NIPAM) and 6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate (MAZO). The resultant copolymers, combining photo-responsive moieties with thermal-responsive moieties, possess photo- and temperature- dual-responsive property, among of which, PNIPAM shows lower critical solution temperature (LCST) and PMAZO exhibits reversible trans-cis isomerization under UV/vis irradiation. In selective solution they can form selective micro-tunnel with excellent controlled release, and can be used as drug carrier and controllable membrane.

Abstract: The high-powered brazing diamond saw was developed to cut vehicle tyre efficiently. The Ti-coated diamond and the uncoated diamond were brazed with NiCr alloy by high-frequency induction under argon atmosphere at 1020°C within 10 seconds. The interfacial microstructures between brazed diamond and the filler alloy were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersion spectrometer (EDS). It is surprisedly found that Cr-carbides forms compactly and normally on the surface of Ti-coated diamond brazed, whereas Cr-carbide forms loosely and tangentially on the surface of uncoated diamond brazed. The abrade experiment results for the brazed diamonds show that the bond strength between the Cr-carbide and uncoated diamond brazed is lower than the normally formed Cr-carbide and the diamond. Furthermore, the cause that Ti changes the morphology of Cr-carbides on the surface of Ti-coated diamond brazed is discussed by the further tests that are specially designed.

Abstract: To explore the substantial cause of the early abnormal wear of micro-vehicle clutch’s friction material, the sample test aimed at studying the tribological properties of micro-vehicle clutch’s friction material is designed, according to GB/5763-98 national test standards. The broken line graph of samples’ friction coefficient on and wear rates in different working conditions are obtained. There are two types of working conditions. One is the same line speed and different working loads of samples, and the other is the same working load and different line speeds. Combined Scanning Electron Microscopy (SEM)’s observation with tribological principle, the sample test result is analyzed, thus obtaining the changing rules of the materials’ friction coefficient and wear rates at different temperatures, working loads and line speeds.

Abstract: The plastic injection molding is widely used for the manufacturing of complicated-shaped and high value-added products. The plastic injection molding machine is the most important equipment for the industry. This paper focuses on the mold separation (MS) of the injection molding machines. The characteristics of the MS of injection molding machine with different clamping units are systemically analyzed, the five-hinge joint-double toggle clamping unit and the direct hydraulic pressure clamping unit included. The study points out there are several typical differences between the different clamping units. Meanwhile, it shows there is a linear relation between the MS value and the product weight, and explains why the MS signal can be used to control the injection molding process.

Abstract: The melting and recrystallization behavior of Poly(ethylene terephthalate) (PET)/SiO2 nanocomposites after isothermal crystallization from the melt was studied by Step-scan differential scanning calorimetry (SDSC). The influence of SiO2 contents, crystallization temperature and crystallization time on the melting process were examined. Two melting endotherms(in the SDSC CP.A curves, reversible part) and one recrystallization exotherm (in the SDSC CP.IsoK curves, irreversible part)of PET/SiO2 nanocomposites after isothermal crystallization were observed during the melt process. This ascribes to the melting-recrystallization mechanism .The low temperature endotherm attributes to the melting of primary crystal formed during the isothermal treating and the high temperature endotherm resulting from the melting of recrystallization materials. The reason why more recrystallization happened with the increase of SiO2 content was given and the process of recrystallization was described in detail. The effects of crystal perfection and recrystallization were minimized by increasing of crystallization temperature and time.

Abstract: Polysulfone (PSf) membranes were prepared by the wet-phase-inversion using 1-hexadecyl-3-methylimidazolium thiocyanate [C16mim][SCN] as an new additive. Scanning electron microscope was utilized to visualize cross-sections of the membranes to gain more better understanding the influence of [C16mim][SCN] on the pore-forming. Moreover, Membrane-forming mechanism using ionic liquid as a pore-former was also discussed. The results showed that ionic liquid [C16mim][SCN] had restrained the demixing of the casting solutions and has the ability of the pore-forming, higher than those of its analogues of PEG400. With increase of concentration of ionic liquid [C16mim][SCN] in casting solutions, the structures of the membranes changed from asymmetric finger pores to the spongy-finger-macrovoid structure of the pores. Compared with PEG400 as a pore-former,[C16mim][SCN] has the pore-forming ability to the membrane at lower concentration of [C16mim][SCN] in the casting solution. Especially, at the 4:76 ratio of [C16mim][SCN]/NMP, the prepared membrane has the asymmetric finger-pores structure, with the 2~6μm pores close to surface layer and the 10~24μm pore for its sublayer. Its retention rate of PEG10000 and solution flux are 97.1% and 48.7 L• h-1• m-2. Meanwhile, ionic liquid can be a plasticizer, according the thermal properties of the membranes.

Abstract: Molecularly imprinted composite membranes for selective binding and permeation of roxithromycin were prepared by means of thermal initiated co-polymerization method using polysulfone ultra-filtration membranes as porous supports. Scanning electron microscope was utilized to visualize surface and cross-sections of the membranes to gain more better understanding in the analysis of imprinted layers deposited on PSF support membranes and differential scanning calorimetric was used for determining the thermal stability of the membranes. Static equilibrium binding and recognition properties of the imprinted and non-imprinted membranes to roxithromycin and its analogues in ethanol solution system were tested. The results showed that saturated binding capacity of imprinted membrane to roxithromycin was about 2.24μmol/g, higher than those of its analogues, and the selectivity factors of αRM/EM, αRM/AM and αRM/EE were 1.75, 2.46 and 2.67, respectively. The transport performances of the membranes were evaluated through kinetic filtration experiments. The separation mechanism of the roxithromycin imprinted membrane could be defined as facilitated permeation mechanism.

Abstract: The thermal conductivities of two rubbers filled with different carbon black (N330 and N375) are measured by experiments, and compared with five theoretical models calculated results. It is shown that thermal conductivity of carbon-filled rubber is obviously enhanced with increase of the volume filler fraction of carbon black and the thermal conductivity of carbon-filled rubber is related to the microstructure and morphology of carbon black. The estimated thermal conductivities by using the model proposed in our previous paper are of the same variation as the experimental ones of N330 carbon/rubber and N375 carbon/rubber during the range of volume fraction from 2% to 20%.

Abstract: In order to improve the performance of polymer modified porous concrete (PMPC), the mineral admixtures (MAs) including fly ash (FA) and silicon fume (SF), are added in the concrete. In this paper, the optimum dosage of the MAs, the influence of the MAs on the strength performance, permeability performance and the surface functional performance of PMPC are studied. The microscopic test of SEM is used to explore the microscopic structure of PMPC. The test results indicate that: the dosage of 10% FA or of 6% SF is the optimum dosage, while the 28d compressive strength can reach 24MPa and 43MPa, respectively, the 28d flexural strength can reach 5.2MPa and 5.3MPa, respectively, and the permeability coefficient can reach 0.36cm/s and 0.32cm/s, respectively. The surface structural depth can reach more than 1mm and the slide resistance coefficient can reach more than 40BPN, which can conform to the standard of JTG F30-2003. The Contact Element Model is proved to conform to the structural features of PMPC. With the microscopic test, as the addition of the polymer and MAs, the internal micro-cracks and non-hydrated cement particles in the interfacial transition zone (ITZ) are covered by the cement paste and polymer films. The contact area, the mechanical property and durability of PMPC can be improved.