Advanced Materials Research Vols. 476-478

Abstract: An accelerated ageing test equipment with the pressure transducer and digital indicator is designed in the light of the features that the rubber seal used in aviation industry always stand compression stress. This equipment can do real-time monitor on the compression stress of rubber materials in accelerated ageing test. The stress measurement range is 0～980 N, and the temperature fluctuation range is 0～200°C. With this equipment, the compression stress relaxation and stress permanent set can be tested and the relationship between them in 100°C can be found.

Abstract: The crystallization of isotactic polypropylene (iPP) and polypropylene/polyethylene-glycol （iPP/PEG） blends were investigated by in situ Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). It was found that the existence of polyethylene-glycol（PEG） does not destroy the helical structure of iPP in the melt, but changes the crystal structure of iPP in the bends. Moreover, the variation tendency of ratios of intensity A998 cm-1/A1460 cm-1 for iPP and iPP/PEG blends showed that the the onset crystallization temperature of iPP is improved by addition of PEG until the PEG content reaches to 5 wt%, and beyond this content, the crystallization point decreases.

Abstract: In this paper, a various shape-memory materials had been prepared by two-stage curing method. The purpose of using this approach was to maintain the excellent shape memory properties and low glass transition temperature (Tg) of shape-memory materials after first stage curing, furthermore, improve the Tg and heat resistence effectively after second stage curing. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and fold-deploy shape memory tests were used to characterize the feasibility of two-stage curing, thermodynamics properties and shape memory performance of these polymers. DSC results showed that two different curing stages could be achieved successfully, DMA results suggested that heat resistance of materials had been improved after second curing stage, while the fold-deploy shape memory tests proved that the composites possessed excellent shape memory properties, it could be deformed into different shape and recovered its original shape fully within three minutes.

Abstract: The research focused on the effect of shear intensity on the crystallization process and the properties of the PA1010/CaCl2 composites which were prepared through melting extrusion. The results showed that, the interplanar distance, the crystallinity and the wavenumbers all had an extreme value when the screw speed was 240r/min. With the increasing of the shear intensity, the complexation between PA1010 and CaCl2 increased first and then decreased. The tensile strength and the heat distortion temperature of the samples increased first and then decreased, and the melt index decreased first and then increased, when the screw speed changed from 160r/min to 320r/min. All of them had an extreme value when the screw speed was 240r/min. The tensile yield strength, the flexural strength decreased with increasing of screw speed, and increased slightly or tended to a fixed value when the screw speed was more than 280r/min. The Izod impact strength rapidly decreased from 62MPa to 40.3MPa when the screw speed changed from 160r/min to 240r/min, then increased slowly with increasing of the shear intensity. The appropriate screw speed of the large-scale continuous production for the PA1010/CaCl2 composites was from 200r/min to 240r/min.

Abstract: Gelatin microspheres (GMSs) were prepared by the inverse suspension cross-linking reaction, using glutaraldehyde as the cross-linking reagent. The GMSs was characterised by scanning electron microscopy and FTIR spectra. Langmuir, Freundlich isotherms were used to analyze the adsorption equilibrium of the food red 3 (FR3) onto GMSs and related correlation coefficients have been determined at different temperatures. The adsorption data fitted well with Langmuir isotherm model and the adsorption of FR3 onto GMSs is a favorable process. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° have also been evaluated and it has been proved that the adsorption process is spontaneous and endothermic.

Abstract: Poly(ethylene terephthalate-co-4,4’-bibenzoate)s (PETBBs) with 0-25mol% bibenzoate unit were prepared from terephthalic acid (PTA), 4,4'- bibenzoic acid (BBA) and ethylene glycol (EG). The chemical composition and number-average sequence length of the resultant PETBBs were investigated by 13C-NMR. It was improved that the chemical composition of PETBBs is identical with the feed ratio, and the number-average sequence length of PET segment (LPET) becomes reduced with increasing BBA unit. The molecular weights of PETBBs reaches the high level for practical use. DSC analysis explains that the glass transition temperature (Tg) increases almost linearly and the crystallization becomes difficulty with increasing content of BBA unit. X-ray diffraction also illustrates that both crystallinity and crystal size reduced as more BBA unit is incorporated. Moreover, the relationship between the number-average sequence length and the melting temperature was investigated. The linear correlation between the number-average sequence length (LPET) and the melting temperature was observed.

Abstract: using polyetherketone(PEK), modified polytetrafluoroethene(PTFE), modified glass fiber, zinc oxide and asbestos fiber as raw material, use self-made portable gasket production device to produce gasket. gasket is installed on the flange that is on specially crafted oil high temperature detecting device pipeline, and use the flue gas monitor device detect sealing. The experimental results show that, When the mass percentage of the material were: ketone28%, modified PTFE 26%, modified glass fiber 7%, zinc oxide 23% and asbestos fiber 6%, conducting oil temperature of 350 °C, the pressure ≤ 0.5MPa, it did not detect the leakage of heat conducting oil .contrasting stainless steel gasket spiral wound gasket, special oil resistant asbestos mat, this composite material is more suitable for special high-temperature heat-conducting oil sealing.

Abstract: Abstract. The thermal aging experiments on nitrile rubber and rubber additives were carried out for different time in 25# transformer oil at 70°C. The amount of CH4 released from non-rubber group, nitrile rubber group and rubber additives group were measured by Gas Chromatography (GC). The molecular structure of NBR matrix and liquid extracted from NBR were analyzed with fourier transform infrared analysis (FTIR), respectively. At last, the formation mechanism of CH4 in nitrile rubber were investigated. The results illustrated that the rubber additive RD released methyl radicals and hydrogen radicals, and generated CH4 by reacted with each other.

Abstract: A new kind of star cationic polyacrylamide (S-CPAM) based on AM and DMC was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure of the resulting product was characterized by FT-IR. S-CPAM was used as retention aid for papermaking and the influence of the application conditions such as dosage of S-CPAM, shearing, action time and pH value on the performance of S-CPAM were also investigated. The results showed that the S-CPAM could improve fines and fillers retention markedly by bridging mechanism and was relatively insensitive to shearing and pH value of the papermaking system.

Abstract: Based on the nitrile rubber accelerated life tests, using the stress relaxation coefficient changes as the aging performance indicators, the relationship between NBR’s stress relaxation and aging time was given ,and also the NBR’s aging dynamic equation was established to predict of the material’s storage life in the normal storage temperature and storage time ,which can be used as reference to predicte NBR’s storage life .