Advanced Materials Research Vols. 550-553

Abstract: Different sulfates were used as the catalysts of polyethylene terephthalate (PET) depolymerization under microwave of 250 watts, in which ZnSO₄ presented the best catalysis in this reaction, and the depolymerization degree (DPD) of PET was reached to 90 %. It was found that the depolymerization was occurred simultaneously on the surface and the internal parts of PET chips by the observation of scanning electron microscope (SEM) images. In addition, DPD increased with the improvement of the polarization forces of these sulfates.

Abstract: A flow-injection chemiluminescence (FI-CL) sensor for metformin determination based on recognition materials of molecularly imprinted polymers (MIP) is reported. The sensor was fabricated by packing the MIP particles into a V-shape flow cell. Metformin could be selectively on-line adsorbed by the MIPs and then sensed by its great enhancing effect on the weak CL reaction between N-bromosuccinimide (NBS) and fluorescein. The CL intensity was linear to metformin concentration in the range from 2×10−8 to 8×10−6 g•mL−1 and the limit of detection (L.O.D.) was 6×10−9 g•mL−1 (3σ). The sensor showed high selectivity, improved sensitivity and excellent stability and reversibility compared with the CL method without using MIPs. The lifetime of the sensor was investigated and MIPs could be reused for more than 200 times. The sensor has been directly applied to determine metformin in human urine.

Abstract: To solve the solubility problem of conductive poly (3,4-ethylenedioxy thiophene) (PEDOT), PEDOT was synthesized from polymerization of 3,4-ethylenedioxy thiophene (EDOT) in aqueous lignosulfonate (LS) solutions with ammonium persulfate as the oxidant. Results showed that conductive polymer PEDOT was successfully obtained in the present of LS, and the PEDOT/LS conductive compounds could be well dispersed into water. The effective diameter of the PEDOT/LS compounds decreased with increasing feed ratio of EDOT:LS. When the EDOT:LS ratio was up to 3.5:1, the effective diameter of PEDOT/LS was about 100 nm as detected by light scattering and TEM. The surface resistance of PEDOT/LS coating was about 107 Ω/sq, and had little change after treatment of washing and heating, so the PEDOT/LS dispersion could be used as a good antistatic agent.

Abstract: Several polycarboxylate superplasticizers (PCs) with different side-chain structure have been synthesized. The effect of side-chain structure of PCs on hydration of C₃A has been investigated by XRD, TG-DSC and SEM. The results show that PCs restrain hydration of C₃A as a whole, but accelerate formation of Al(OH)₃ and C₃AH₆; with increase molecular weight of long-side-chain, hydration of C₃A is slowed, and the formation of Al (OH)₃ and C₂AH₈ also become slowed. With increase proportion of long-side-chain, hydration of C₃A and formation of C₃AH₆ are slowed, but existence of C₂AH₈ become obvious. The six-party flake hydrated products of C₃AH₆ are formed with a large number of grafted carboxyl.

Abstract: In this paper, the blended materials of poly(lactic acid) (PLA) and thermal plastic starch (TPS) under the plasticization of polyethylene glycol (PEG) 200 were prepared. By detecting the thermal, rheological and tensile properties, it evaluated the plasticization effect of PEG 200 on blended materials. Specifically, for thermal properties, the addition of PEG 200 could improve mobile ability of PLA macromolecules, and accelerated them to form crystalline. But if the content of PEG 200 was more than 10%, this effect was impaired. For rheological properties, PEG 200 could change the fusant of blended materials from pseudoplastic fluid to newton fluid. However, if the PEG 200 was added too much, the blended material was too like perfect newton fluid to be prepared suitably. For tensile properties, when content of PEG 200 was more than 10%, the elongation and tensile modulus would changed sharply. All in all, 10% was the suitable addition parameter for PEG 200. Above this content, the plasticization effect of PEG 200 was too strong to impaired materials properties.

Abstract: Polyurethane (PU) prepolymer with the isocyanine-based were synthesized by toluene -2, 4-diisocyanate (TDI), polyethylene glycol (PEG-400) and polyethylene glycol (PEG-1000) with N-methylpyrrolidone as the solvent. The effects of temperature and time on the synthesis of polyurethane prepolymer were examined in this paper. The structures of PU, unmodified epoxy resin and modified epoxy resin were identified by FI-IR spectra. It was shown that polyurethane prepolymer was synthesized at 70°C for 5 hours and modified epoxy resin was synthesized successfully.

Abstract: A series of multiblock thermoplastic ploy(ester imide ether)s elastomers derived from polytetramethylene glycol of molecule weight is 1000 (PTMG1000), 1,4-butanediol (BD), and a new imide diacid monomer were synthesized of Pyromellitic dianhydride (PMDA) and glycine (GLY). was synthesized by two-step melting polycondensation method. Their chemical structures were studied by 1H-NMR spectroscopy as well as their thermal properties of the copolymers were investigated from differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), respectively. Otherwise, the solubility of these polymers was characterized by various organic solvents. The effects of the hard/soft segment content on the thermal properties and soluble behavior were investigated. The result demonstrated that these copolymers had better thermal properties (Tm: 225~280°C and T5% : 350~353°C) than those of conventional thermoplastic elastomers due to the introduction of imide bond. At the same time, the polymers have good solubility.

Abstract: Reinforced soil has been among the most effective soil modification materials. Its use has been expanded rapidly into civil engineering, geotechnical engineering and pavement engineering. Reinforcing subgarde in pavement systems has always been an issue. This study focuses on effect of fiber inclusion on the strength of subgrade material. Plastic fiber was used for this investigation. Fiber contents and aspect ratio have been changed during these tests. The fiber percentage varied from 0 % (for unreinforced samples) to 4%. Clay was used as sub grade material. Unconfined compression tests were carried out to investigate behaviour of the composite under different condition. The fiber length and fiber content found to play important rule on the strength of composite. Furthermore it was observed that ductility of sample increased by fiber inclusion. Finally, UCS was carried out for cemented clay samples and fibre played an important role to reduce the brittle behavior of the cemented samples.

Abstract: Keywords: Visco-elastic property; polymer flooding; oil recovery Abstract. Polymer flooding and ASP flooding has improved oil recovery a lot in Daqing oil field. In ASP flooding, the existence of alkali decreases the visco-elastic characteristic of polymer, which decreases the oil recovery of polymer flooding. The aim of this paper was to study the visco-elastic characteristic, shear resistance in high concentration and high molecular weight polymer flooding, and analyzed the suitable parameter of it .They can provide the theory of polymer flooding development and application research.

Abstract: The thermal degradation behavior of PVC stabilized by the organotin were investigated by means of the thermogravimetric analysis and non-isothermal multiple scanning method. The results indicate that the lowest decomposition temperature is greater than 210°C in the conversion rate of 5%. The decomposition process occurred in three stages. The results calculated by Kissinger, Ozawa, Starink and Friedman methods show that the average apparent activation energy in first, second and third phase is 98.46kJ/mol, 111.24kJ/mol and 243.23kJ/mol respectively. In the initial reaction (α<10%), the decomposition reaction is controlled by the first order (F1) mechanism, with a half-life of 4.92h at 180°C.