The melt elastic behavior of polypropylene/glass bead composites in capillary flow

The melt extrudate swell and entry pressure losses are important characteristics of elastic properties during die extrusion of polymeric fluids. They are usually expressed with die-swell ratio (B) and entry pressure drop (ΔP_o). In the present paper, the die-swell behavior and entrance pressure drop of a polypropylene (PP) filled with A-glass beads were investigated by using a Rosand capillary rheometer to identify the effects of the filler contents and extrusion rate on the elastic behavior of the sample melts. The experiments were carried out under the conditions with an apparent shear rate range of 50–10⁴ s⁻¹ and a temperature of 190 °C. The results showed that B increased nonlinearly with increasing shear rate at the wall (γ_w), and increased linearly with the increase of shear stress at the wall (τ_w). With the increase of the volume fraction of the fillers B decreased nonlinearly. Similarly, the entry pressure drop increased linearly with the increase of τ_w, whereas the influence of the filler concentration on ΔP_o was insignificant in this case. Furthermore, B increased as a linear function of ΔP_o, and extension stress (σ_e) increased nonlinearly with increasing γ_w.     

Thermoanalytical studies on specialty polymers in Japan

Thermoanalytical studies on specialty polymers in Japan are reviewed. The basic and applied researches for the developments of new specialty polymers such as high-performance polymers, liquid crystalline polymers, and biodegradable polymers during the 1990's are introduced from the standpoint of thermal analysis. Many studies were performed for the improvements of durability and thermal stability of engineering polymers, biodegradable polymers and so on. A special topic of researches on the thermal behavior of polymers by high-pressure differential thermal analysis is included in this review. This revised version was published online in July 2006 with corrections to the Cover Date.     

PET伸直链结晶体的研究进展

对聚对苯二甲酸乙二醇酯（PET）在特定的结晶条件下是否生成伸直链晶体进行了论证,系统总结了伸直链晶体形成的证据,并讨论了PET伸直链晶体形成的机理。     

表面膨胀粘度的测定研究

用不同浓度的NaCl和表面活性剂直链的十二烷基苯磺酸钠(LAS)、稳定剂聚丙烯酰胺和水所组成的泡沫体系为研究对象,通过表面压松弛的方法,利用计算机数据拟合,得到了计算表面膨胀粘度的方法。     

Compact apparatus for rapid measurement of high-pressure phase equilibria of carbon dioxide expanded liquids

A new apparatus based on a synthetic method was developed for phase equilibrium measurements. The characteristic features of the apparatus are its light weight (ca. 288 g), variable-volume with a free piston, position sensing device for the piston, precise pressure and temperature control, and a window for visual observation. The inner volume of the cell can vary from 2.5 to 8.8 cm³. The cell was constructed from titanium so that the composition of the sample can be determined by direct weighing of the cell. The apparatus was designed for temperatures up to 473 K and pressures up to 25 MPa.     

A modification to the Peng–Robinson-fitted equation of state for pure substances

In this work we present two modifications to the Peng–Robinson-Fitted equation of state where pure component parameters are regressed to vapor pressure and saturated liquid density data. The first modification (PR-f-mod) is a method that enhances the equation of state pure component property predictions through simple temperature dependent pure component parameters. In the second modification (PR-f-prop) we propose a temperature dependency for co-volume b in the repulsive parameter of the EoS, and revise the temperature function in the attractive term. The agreement with experimental data for 72 pure substances, including highly polar compounds, is remarkably good. We obtain average absolute deviations in saturated liquid density of less than 1% for all substances studied.     

High-pressure synthesis of cyclic phenylacetylene oligomer

New conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100–200°C for 0–5 h. The number-average molecular weight M?_n, the weight-average molecular weight M?_w, and the oligomer yield increased with pressure, tem-perature, and time. The average molecular weight of the oligomer showed the maximum value (M?_n: 830, M?_w: 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV–VIS, field desorption mass (FDMS) spectra, and ¹³C NMR spec-trum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. ¹³C NMR spectrum of the oligomer showed the absence of sp-carbon (? C?). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. © 1995 John Wiley & Sons, Inc.     

Determination of macrolides in livestock excreta by syringe purification coupled with liquid chromatography tandem mass spectrometryEI北大核心CSCD

A method of syringe-dispersive solid-phase extraction combined with ultrahigh performance liquid chromatography with tandem mass spectrometry for the simultanous determination of 10 macrolides in manurebased fertilizers was developed. After extraction with methanol and acetonitrile,the extracts were purified by insyringe dispersion solid-phase extraction in syringes pre-filled with 60 mg PSA and 30 mg C18. The resulted extracts were further separated by a BEH C18 column,detected by multiple reaction monitoring in electrospray positive ion mode,and quantified by matrix-matched external standard method. The results showed that the recoveries of the target compounds ranged from 70% to 110% at three spiked levels（10,30,and 50 μµg/kg）with the relative standard deviations ranged from 1.4% to 12%. The limits of detection and quantification were 0.57 1.75 and 2.77-5.40 μµg/kg,respectively. This method was suitable for the simultaneous determination of residual macrolides in organic fertilizers. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Production of oxygen enriched air by rapid pressure swing adsorption

A novel rapid pressure swing adsorption (RPSA) process is described for production of 25–50% oxygen enriched air. The embodiment consists of one or more pairs of adsorbent layers contained in a single adsorption vessel. The layers undergo simultaneous pressurization-adsorption and simultaneous depressurization-purge steps. A total cycle time of 6–20 seconds is used. The process yields a very large specific oxygen production rate and a reasonable oxygen recovery for production of 20–50 mole% oxygen enriched gas.It is demonstrated by a simple mathematical model of isothermal single adsorbate pressure swing ad(de)sorption concept on a single adsorbent particle that the specific production rate of a PSA process cannot be indefinitely increased by reducing the cycle time of operation when adsorbate mass transfer resistances are finite.