聚异氰脲酸酯泡沫塑料中三聚体含量测定的研究

利用2,4,6-三(二甲胺基甲基)苯酚作三聚催化剂对纯MD I进行三聚合成,得到一系列不同三聚体浓度的标准样品。利用凝胶渗透色谱(GPC)测定标准样品的异氰脲酸酯三聚体含量,结合衰减全反射傅里叶红外光谱仪(FTIR-ATR)谱图中三聚体吸收峰的强度得到外标工作曲线,由此建立了FTIR-ATR技术测定聚异氰脲酸酯泡沫中异氰脲酸酯三聚体含量的方法。结果表明,通过此方法,可以测定聚异氰脲酸酯泡沫样品中的三聚体含量。     

The determination of frying oil quality using Fourier transform infrared attenuated total reflectance

The possibility of using the whole spectra (wave numbers between 4000 and 850 cm⁻¹) from Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) to differentiate between good, marginal and unacceptable oils with regard to various intensities of oil rancidity was investigated. Fresh, used, and discarded oils were collected from several fast food restaurants from each frying cycle for 4 weeks. Dielectric constant, peroxide value, free fatty acid content, and density of oil samples significantly (P<0.01) increased with frying time. The correlation (r) between FTIR absorbance at 3300 cm⁻¹ and free fatty acid content was from 0.84 to 0.94 for oils from the three restaurants. Similarly, the correlation between FTIR absorbance at 3471 cm⁻¹ and peroxide value was from 0.90 to 0.97. The results of principal component analysis using the whole spectra (4000-850 cm⁻¹) showed good discrimination and stability for identification between acceptable, marginal and unacceptable frying oils.     

Evaluation of the effect of vinyltrimethoxysilane on corrosion resistance and adhesion strength of epoxy coated AA1050

The quality of surface treatment of aluminum alloy (AA1050) with vinyltrimethoxysilane (VTMS) was examined. Calculated surface energy with Van Oss, Chaudury and Good (VOCG) method showed higher surface energy of treated specimens. Chemical interaction between silane layer and aluminium surface was examined via FTIR-ATR. In addition, practical adhesion was measured in dry, wet and recovered states via pull-off method and compared to adhesion strength of desmutted and chromated specimens. Results showed good adhesion performance in dry state for silane treated specimens. Corrosion protective performance of epoxy coating in the presence of silane layer on aluminum was studied with Electrochemical Impedance Spectroscopy (EIS) and compared with coated desmutted and chromated specimens. Water sensitivity of silane layer resulted in poor protective performance of specimens treated at pH > isoelectric point (IEP).     

Antioxidant Properties of Genistein in a Model Edible Oil System

ABSTRACT:  Antioxidant properties of genistein were tested during the low temperature oxidation of linseed oil. Four linseed oil solutions were prepared: linseed oil, linseed oil containing 2 μmol added genistein/g oil, linseed oil containing 4 μmol added genistein/g oil, and linseed oil containing 200 ppm butylated hydroxyanisole (BHA). Dimethyl sulfoxide (DMSO) (1.7%) was added to all solutions to allow for the solubilization of genistein. Antioxidant activities were analyzed using 2 techniques: (i) the oven stability test carried out at 60 °C with periodic determination of peroxide values (PV); and (ii) oxidation on a heated (60 °C) FTIR-ATR crystal with periodic scanning and collection of infrared spectra. Induction points (IP) for each solution were determined. A strong correlation ( r = 0.91) was noted between the 2 analytical methods used. Three significantly ( P < 0.10) different levels of IP were generally observed. The shortest IP (17 h for PV, 36.9 h for FTIR) was found for the linseed oil. Intermediate IP's were obtained for the 2 μmol added genistein/g oil (32.4 h for PV, 43.5 h for FTIR) and 4 μmol added genistein/g oil (33.9 h for PV, 44.2 h for FTIR) samples. The longest IP (39.9 h for PV, 54.2 h for FTIR) was obtained for the 200 ppm BHA containing solution. Although genestein was not as effective as BHT in retarding oxidation, the results clearly demonstrate that it is able to act as an antioxidant in a bulk oil system.     

Rapid monitoring of the spoilage of minced beef stored under conventionally and active packaging conditions using Fourier transform infrared spectroscopy in tandem with chemometrics

Fourier transform infrared (FTIR) spectroscopy was exploited to measure biochemical changes within fresh minced beef in an attempt to rapidly monitor beef spoilage. Minced beef packaged either aerobically, under modified atmosphere and using an active packaging were held from freshness to spoilage at 0, 5, 10, and 15 °C. Frequent FTIR measurements were collected directly from the sample surface using attenuated total reflectance, in parallel the total viable counts of bacteria, the sensory quality and the pH were also determined.     

Improved adhesion of silicone rubber to polyurethane by induced surface reconstruction

Induced surface reconstruction of silicone rubber by blending polydimethylsiloxane (PDMS) reactants with bifunctional PDMS-hydroxyl terminated polybutadiene (PDMS-b-HTPB) copolymers and curing with appropriate mold material was attempted to improve the adhesion of chemically inert silicone rubber to polyurethane (PU). Surface characterization using Fourier transform infrared-attenuated total reflectance indicated that the surface of the silicone rubber possessed a controlled amount of HTPB. The surface was enriched with HTPB by using mold materials having high critical surface tension, such as aluminum. A dynamic surface rearrangement occurred during a 1-h heating cycle at 70°C, changing from an HTPB-enriched surface to a PDMS-enriched surface. The peel strength between the silicone rubber and PU was found to increase with decreased propanol residue and with an increase in critical surface tension of the molding materials. The increased content of surface HTPB was suggested to account for the improved adhesion of silicone rubber to PU. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1669–1675, 1998     

Synthesis of a polydimethylsiloxane-block-hydroxyl grafted acrylate prepolymer copolymer to improve the adhesion between silicone rubber and polyurethane by induced surface reconstruction

A new class of hydroxyl-functionalized polydimethylsiloxane-block-hydroxyl graft acrylate prepolymer (PDMS-b-HGAP) copolymers was synthesized. The copolymers were characterized using Fourier transform infrared spectroscopy as well as ¹H and ¹³C nuclear magnetic resonance spectroscopy. The hydroxyl groups of the HGAP were reacted with the chlorine terminal in the PDMS to yield a triblock copolymer consisting of two segments of PDMS linked to a HGAP segment. The induced surface reconstruction of silicone rubber (SR)by blending polysiloxane reactants with bifunctional PDMS-b-HGAP copolymers and curing using mold materials having high critical surface tension such as polyethyleneterephthalate was attempted to improve the adhesion between chemically-inert SR and polyurethane (PU). Surface characterization using Foruier transform infrared-attenuated total reflectance indicated that the surface of the SR was enriched with HGAP. The increased content of surface HGAP was suggested to account for the improved adhesion between SR and PU.     

用衰减全反射红外光谱研究纳米SiO2粒子在复合涂层中的迁移现象

用衰减全反射红外光谱(FTIR-ATR)技术研究了纳米SiO₂粒子在紫外光固化复合涂层中的迁移现象,并对影响纳米SiO₂粒子在涂层中分布梯度的因素进行了半定量分析。研究结果表明,纳米SiO₂粒子在光固化过程中向涂层接触空气的表面迁移,在表面层富集。当纳米SiO₂粒子含量较高、分子量较小、接枝率较高,或者在极性较大的基体树脂中时,迁移较快,分布梯度较大。      

Molecular and mechanical properties of hydroxypropyl methylcellulose solutions during the sol:gel transition

This paper outlines the latest findings in our work to understand the fundamental interactions within hydrated hydroxypropyl methylcellulose (HPMC) at elevated temperature. ATR-FTIR spectroscopy was used to relate molecular interactions to the rheological changes in aqueous HPMC solutions during the sol:gel transition. Sol:gel transition temperatures determined using ATR-FTIR spectroscopy, oscillatory rheology and turbidimetry were in agreement to within experimental error. ATR-FTIR spectroscopy provided direct evidence of increased hydrophobic interactions within the gel network through a shift to lower wavenumber of ν_as(CH) vibrations observed during the gelation process. In addition, the FTIR spectra provide evidence that the structure of the polymer network is different in the thermo-formed gel, to that which exists in viscous solution. Both the rheological and ATR-FTIR data confirmed the supposition that thermal gelation is a two stage process. The first stage has been attributed to the disruption of native cellulosic bundles and this is supported by the changes in both the storage modulus and intensity of the ν(CO) band at low temperatures. The second stage corresponded to phase separation and gelation resulting from increased hydrophobic interactions between polymer chains at elevated temperatures.