磁场对泡沫钻井液电导率的影响研究

磁处理技术是利用磁场对非铁磁性流体作用．使被作用物的性质产生某些期望的变化，从而改善生产效果和使用效益。磁处理对常规钻井液流变性能的影响研究结果表明，磁化能明显改善钻井液性能。通过研究磁化后泡沫钻井液的性质．测定与控制钻井液的电导率，以便从电测曲线上取得更好的地层特性评价。泡沫钻井液的电导率与密度基本呈线性关系，电导率随密度的升高而变大；磁处理后泡沫钻井液的性质发生明显改变．泡沫钻井液的电导率有不同程度的下降，在磁场强度为100mT、蜂数为2的磁场条件下泡沫钻井液的电导率变化率降低最大，电导率平均下降16％左右。     

Development of polyurethane elastomer composite materials by addition of milled fiberglass with coupling agent

Polyurethane elastomer composites were developed using milled fiberglass and their mechanical properties were studied. In particular, the organically chemical treatment of the milled fiberglass was investigated in detail. It was demonstrated that both strength and toughness of the resulting elastomer composites were improved considerably with the addition content of fiberglass. Furthermore, it was indicated that the optimal properties can be achieved by the proper addition of milled fiberglass that was chemically treated using coupling agent.     

Role of chain symmetry and hydrogen bonding in segmented copolymers with monodisperse hard segments

Thermoplastic segmented polyurethane and polyurea copolymers whose monodisperse hard segments are based on only a single diisocyanate molecule are discussed. The solid-state structure-property behavior of these materials demonstrates that a proper selection of the level of symmetry and/or cohesiveness of the hard microdomains may allow elimination of the traditional requirement of chain extension to obtain melt processable segmented urethanes, and more specifically, urea copolymers with useful structural properties.     

Polyimide foams from powder: Experimental analysis of competitive diffusion phenomena

In the present study, various diffusive processes have been investigated during foaming of powdered precursors of polyimide. A detailed analysis of the powdered precursor's characteristics allows for an enhanced morphological understanding of the resulting microstructures and foam unit cell. Parameters that are central to the foaming process such as particle morphology, volatile concentration and sorption-desorption processes are evaluated. Isothermal and non-isothermal desorption experiments have been carried out by thermogravimetric analysis (TGA), and specific diffusive processes have been correlated to thermodynamic and kinetic transitions by means of modulated differential scanning calorimetry (MDSC) of the corresponding materials. It was found that two primary fluxes of volatiles, one out of the external surface of the particles (responsible for volatile desorption) and the other into the growing bubble (responsible for vapor supersaturation inside the bubble) compete against each other creating a competitive scenario that becomes the controlling factor for potential inflation within the precursor particles.     

Making polyurethane foams from microemulsions

A remarkable correlation exists between the degree of expansion of polyurethane foams and the structure of the reacting premixes. Polyurethane foams obtained from reacting premixes containing microemulsions are highly expanded. The expansion rate is proportional to the volume fraction of microemulsion in the premix. The stability of premixes with and without microemulsion is completely different suggesting distinct creaming mechanisms. We apply this idea to synthesize polyurethane foams from microemulsions successfully. This approach can be used to rationalize the design of polyurethane formulations leading to highly expanded foams.     

Prediction of foam growth and its nucleation in free and limited expansion

The influence volume approach (IVA) is often utilized for modeling the mass transfer process dictating bubble growth dynamics in physical foaming. However, the assumed concentration profile in the IVA method is only valid when the changes in dissolved gas concentration are small (less than 5%). In addition, the validity of the IVA method is difficult to justify in chemical foaming applications because of the difficulties involved in defining the dissolved gas concentration profile.In the present work, we define two distinct stages of bubble growth for physical foaming. These two stages are termed as free and limited expansion and are controlled by the bubble nucleation rate. Bubble nucleation is assumed to occur only in the free expansion stage. In this stage, the bubble pressure drops substantially from an initially high pressure in the supersaturated state while the dissolved gas concentration changes very little. The second stage of our two-stage mass transfer model is termed the limited expansion stage and accounts for bubble growth in the late stages of foam evolution, when the pressure changes become small. However, in the limited stage of bubble growth the dissolved gas concentration drops significantly, as the available dissolved gas is depleted. To summarize our two-stage mass transfer model of foam expansion, the pressure difference between the bubble phase and the liquid phase is the primary mechanism for driving mass transfer in the early (free) stages of foam growth and the concentration difference is the driver for bubble growth in the late (limited) stages of growth. The first stage can be regarded as the nucleation stage and it is relatively short; while the second stage can be regarded as the bubble growth stage and is much longer. Most of the bubble volume expansion takes place in the second stage.The concentration gradient at the bubble edge, which is often ignored in other models, is analyzed in detail in this paper. The details of our novel mass transfer model are also presented.     

棉/氨纶弹力织物低温一浴法染色

通过一种新型染色助剂的应用，有效地降低了氨纶分散染料的染色温度，使棉/氨纶弹力织物能在较低的温度下实行散／活性一浴法同色性染色，获得满意的染色效果。     

Degassing of molten polymers

Degassing is a key-step in polymer processing. Low-molecular-weight components are removed from a polymeric system. The transport of these components takes place by diffusion to the polymer-vapour interface. This interface can be formed by free surfaces of single-phase polymer melts or by bubbles. In this study, the transport with and without bubble nucleation is investigated independently from each other in a special designed apparatus similar to a degassing extruder.The mass transport in thin films and in rotating pools with surface renewal is measured. High surface renewal rates and thick films enhance the mass transfer for single phase flow and bubbly flow. Dimensionless mass transfer coefficients are given as a function of the surface renewal rate, the area of the free surface and the total mass of the polymer. The conditions for bubble nucleation and foam formation are investigated. The bubble nucleation is observed in the rotating pool in the area of high shear velocity.     

Studies on cross-linked polyurethane acrylate-based electrolyte consisting of reactive vinyl/divinyl diluents

A series of cross-linked polyurethane acrylate (PUA) electrolytes have been prepared by using 4,4′-methylene bis(phenyl isocyanate), polyethylene glycol, hydroxyethyl methacrylate and different reactive vinyl/divinyl diluents, such as methyl methacrylate (MMA), ethyl acrylate and acrylonitrile, tripropylene glycol diacrylate (TPGDA). The electrolytes were prepared by UV radiation induced cross-linking of the PUA-diluent mixture followed by swelling in a liquid electrolyte (LP-30). Depending upon the composition of the components, these electrolytes exhibited a wide range of mechanical and electrical properties. The system containing MMA as reactive diluent showed highest conductivity, but poor mechanical properties and stability in the liquid electrolyte. The TPGDA cross-linked system possesses a good combination of ionic conductivity and stability in liquid electrolytes. These systems showed good compatibility with Li-electrodes and sufficient electrochemical stability to allow safe operation in rechargeable Li-batteries.     

消失模精密铸造工艺研究

借助熔模铸造制壳工艺制成消失模铸造用的超薄空腔型壳，以减少消失模铸造在浇注过程中因聚苯乙烯气化而产生的铸件增碳、增氢等缺陷。聚苯乙烯模失模工艺为随炉升温至600℃，保温60min,型壳焙烧工艺为800℃焙烧1h。