Towards advanced circuit board materials: adhesion of copper foil to ultra‐high molecular weight polyethylene composite

Polyethylene based composites are attractive materials for advanced circuit board applications because of their unique combination of properties: low dielectric constant and loss factor, light weight, high flexural modulus and low thermal expansion coefficient controlled in all spatial directions. This investigation describes a process to consolidate chopped fibers of ultra‐high molecular weight polyethylene concurrently with its bonding to a copper foil. Bonding is affected by a thin sheet of low‐density polyethylene, incorporating a crosslinking agent with a concentration gradient across the sheets thickness. In this single step process, the composite material is formed and bonded to the metal foil, achieving good adhesion without the use of extraneous glue. Copyright © 2002 John Wiley & Sons, Ltd.     

镓改性ZSM-5沸石中镓活性中心的形成与表征

采用脉冲微反体系研究了经不同程度还原和不同镓含量的GaZSM-5沸石的芳构化性能与吡啶吸附红外光谱特征谱带吸收度的关联，证实了1458 cm~(-1)吸收带的用于表征与Ga物种有关的活性中心，并研究了沸石的硅铝比对Ga中心形成和Ga的价态对芳构化性能的影响。结果表明，对Ga含量相同的样品来说，硅铝比愈低，起始Ga中心生成量愈多，高价态与低价态的Ga中心对丙烷芳构化反应都有促进作用。     

Inorganic electrides

Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.     

Pt/HL和Pt/KL沸石在异丙醇分解反应中的不同催化行为

Ｐｔ／ＫＬ沸石在异丙醇分解反应中具有很高的脱氢活性,而Ｐｔ／ＨＬ沸石具有明显的缺电子性,在此反应中难以显示出脱氢活性,通过加氢作用,可使沸石的酸位免受积炭覆盖,从而可增强Ｐｔ／ＨＬ沸石的酸性催化作用。     

铜配合物在Y型分子筛超笼中的组装及其催化苯酚羟化活性

 详尽介绍了通过分步法，在Y型分子筛超笼中制备铜（II）- 1，10菲咯啉和8-羟基喹啉配合物（简称CuPhen/Y，CuOx/Y）的过程；活性评价结果显示同Cu/Y相比，以H2O2为氧化剂，CuPhen/Y，CuOx/Y具有特殊的催化苯酚羟化功能。     

THF—FER沸石的系列研究—1．晶体结构稳定性

四氢呋喃（THF）-Na2O-SiO2-Al2O3-H2O体系水热合成的THF-FER沸石，经酸交 换-焙烧脱THF（Ⅰ）或焙烧脱THF-酸交换（Ⅱ）的不同方式处理，均可制得低钠H- FER沸石。经XRD，^27Al与^29Si MAS NMR,低温氮吸附等表征证明，通过1273K高温 的热处理和1073K饱和水蒸气下的水热处理，H-FER沸石骨架保持高度稳定。在高温 水蒸气作用下，Si(2Al）容易从骨架上脱离，而Si(1Al）则保持相对稳定，以（Ⅱ ）方法处理，制备的H-FER沸石在水热条件下易产生较多的硅差劲基缺陷。经高温 热和水热处理后，H-FER沸石孔道结构基本保持完美、开放。     

Comparative quantum chemical studies in the framework of Gaussian approximations of the acidic characteristics of the simplest zeolite clusters and of the sulfuric acid molecule

Different variants of the Gaussian approximation, giving the energetic characteristics of molecules with chemical accuracy (±2 kcal mol^–1), are applied to calculations of the deprotonation energy of the sulfuric acid molecule in the gas phase as well as to the simplest clusters modeling the bridging hydroxyl groups in zeolites, The conclusion is made that the bridging hydroxyls am more acidic than the sulfuric acid molecule. The estimated range of deprotonation energy in zeolites (275±15 kcal mol^–1), is in good agreement with experimental data and with results ofab initio calculations for extended models including several tens of atoms. The effects of the quality of the basis set and electron correlation on deprotonation energy are also discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1641–1647, July, 1996.     

Modification of solids with volatile organics III: Natural zeolites

Summary The effect of pre-adsorbed benzene and ethanol on the adsorptive properties of natural zeolite (clinoptilolite) has been studied by gas-solid chromatography. It has been shown that modification of the solid surface by volatile organics has a significant influence on the adsorptive properties. The modification is of the same order as the more difficult modification by inorganics, as illustrated here by clinoptilolite modification with Co²⁺. Energy distribution of surface adsorptive sites appears to be continuous and confirms previous finding that only a small proportion of active sites is responsible for most adsorbate retention. Part II reference [4]     

Diffusion Mechanisms of Zeolite Catalysts

The diffusion mechanisms within zeolite catalysts, such as resistance to diffusion at pore mouths, configurational diffusion, adsorption-controlled diffusion, influence of co-existing molecules and pore blocking, were overviewed. Two kinds of diffusivities, the intracrystalline diffusivity and the effective diffusivity, were discussed separately to clarify the diffusion mechanism.     

Measurement of Diffusion in Zeolites—A Never Ending Challenge?

A review is given on the main problems associated with the determination and interpretation of molecular diffusion in zeolites. It is shown that the diffusivities may most decisively depend on the relevant space and time scales of observation, as well as on the physical state under which the measurements are carried out. Special emphasis is given to the microscopic techniques and their most recent evidence on the existence of transport resistances distributed over the intracrystalline space.