Advanced Materials Research Vols. 834-836

Abstract: The reason for the natural rubber latex giving out stink during long-term storage or transportation was studied. The stinky component in the latex detected by gas chromatography-mass spectrometry was phenol, the generated content of which increases as the storage temperature rising. It is most possible that the phenol was generated from the decomposition of the inwall coating of iron bucket which loading the natural rubber latex in the strong alkaline during the long-term and high-temperature storage.

Abstract: Polymer phase change microcapsules were prepared through microwave-assisted emulsion polymerization, with the core of hexadecane, the shell of styrene, the emulsifier of sodium dodecyl sulfate, the initiator of potassium persulfate. A few of key factors which can influence the thermal performance and the encapsulation, such as emulsifiers, initiators, temperature and reaction time were investigated. FTIR and DSC were employed to characterize the structure, the phase transition temperature and latent heat.

Abstract: Phenol and dichloroethane with a weight ratio of 3:2 were prepared as a mixed solvent for bulk Polyamide 6 (PA 6) polymer to form PA 6 films. Thermogravimetric Analyzer was used to analyze the degradation behavior of the PA 6 films. The results showed that the bulk PA 6 underwent a one-step thermal degradation process, but the PA 6 films underwent a two-step thermal degradation process. The junction points of the two degradation steps in the PA 6 films appeared at 410-425 °C. The thermal stability of the PA 6 films prepared from the mixed solvent obviously is lower than that of the bulk PA 6 polymer.

Abstract: Shape recovery is a critical characterization of the Shape Memory Polymers (SMP); so far, there has not been a set of uniform specifications, however, on the deformation recovery characterization of SMP, more exactly, on the shape recovery ratio measurement. A simple and effective experimental method is designed to obtain the shape recovery ratio of SMP; and a series of experiments are carried out to measure the shape recovery ratio of a thermoset shape-memory epoxy resin within the finite bending deformation at various test temperatures. And the results show that the shape recovery ratio and rate of the thin sample are larger than that of the thick one; the deformation curvature has little effect on the shape recovery ratio with the test temperatures over, or below, the glass-transition temperature, T_g, but has significant effect near T_g. The conclusions provide an important basis for the structural design of SMP.

Abstract: In order to improve the effect of explosive hardening and reduce the production cost, the elastic-plastic explosive which consists of RDX, rubber, deterrent, antioxidant and plasticizer was prepared. The experiments including density testing, detonation performance, detonation velocity testing, impact sensitivity, and explosive hardening were carried out. The results show that the density of the elastic-plastic explosive is 1.46g/cm3, the detonation velocity is 6670m/s, the impact sensitivity is 28% and the elastic-plastic explosive can be detonated reliably by a detonator. The explosion hardening on Hadfield steel makes the hardness increased from 187HB to 362HB, which increases by 93.5%.

Abstract: In this paper, vinyl-terminated polyurethane was synthesized with polypropylene glycol (PPG, Mn=1000) and toluene diisocyanate (TDI) as raw materials and hydroxyethyl acrylate as the blocking agent. Then the alcohol soluble acrylate-polyurethane (PU) adhesive for low surface energy substrate was acquired from vinyl acetate, acrylate and vinyl-terminated PU by solution polymerization. The resin was characterized by Infrared spectroscopy (IR), thermogravimetry analyses (TGA) and differential scanning calorimetry (DSC) respectively. Adhesion performance to biaxially oriented polypropylene (BOPP) was also studied. The results showed that the incorporation of PU can improve the viscosity, heat resistant, peel-off strength of the adhesive.

Abstract: The natural rubber samples produced by conventional tapping methods were used as a control, then analyzed the dry rubber property of natural rubber, the dynamic property and Physical & mechanical property of vulcanized rubber using Rubber processing analyzer and Thermogravimetric Analyze the difference between the properties of dry rubber and vulcanized rubber produced by Micro-cut Tapping with Gas-stimulation. The results indicated that the tensile strength, tear strength elastic modulus of dry rubber that produced by Micro-cut Tapping with Gas-stimulation are respectively 20%, 7% lower than the control. The protein content of dry rubber materials produced by Micro-cut Tapping with Gas-stimulation is 16.7% higher than control group.

Abstract: Long-term used insulator for power transmission may suffer heavy aging problems for outdoor environment, such as rain corrosion. For Si-Rubber material, the chemical attributes under bad dielectric condition are good indicators for on-line equipment safety alert. In this work, both principle and experiment research were undertaken for the T2 measurements by NMR method. The problems of un-quantitative for other convenient methods had been solved. Most importantly, the chemical reasons for insulator aging has been analyzed for the first time. The results show that the relaxation time would decrease sensitively as the aging increases. In future NMR data scaling will be accomplished by virtue of DC impedance measurements.

Abstract: CIP particles first were coated with SiO₂ shell by the Stober process , then grafted the polyaniline by in-situ polymerization to prepare CIP/SiO₂/PANI core-shell composites. The CIP/SiO₂/PANI composites are composed the dielectric loss properties with the the magnetic loss properties, the morphologystructure and electromagnetic properties are characterized by SEMXRD and vector network analyzer, respectively. It is observed that SiO₂ and PANI are on the surface of CIP particles, XRD patterns further confirm that the CIP/SiO₂/PANI composites are synthesized successfully, and that interaction between components exist in the polymerization. In comparison with CIP, the complex permittivity of CIP/SiO₂/PANI composites have certain enhancement in 2-18GHz frequency range, but it has a very small impact on the complex permeability.

Abstract: Composite stiffened plate structure is widely used in aviation, aerospace and marine areas , in order to ensure the structural reliability ,stability analysis is absolutely necessary. The finite element models are established. In this paper, subspace method and arc-length method are applied to analyze the stability of stiffened panel structure, both two methods are effective. Different stringer parameters will have some impact on the stability, including the number and height. Through analyzing the results, some conclusions are drew for increasing the stability.They have a certain value for engineering application.