Phosphite ester compositions for PVC compounds

The activity of various structural classes of liquid organophosphite esters has been examined in flexible PVC applications. Blends of the most active phosphites have been developed as alternative heat stabilizers for PVC. These new phosphite mixtures eliminate the dependence of compounders upon mixed-metal stabilizer systems based on heavy metals such as barium and cadmium. Static oven aging tests showed the superior performance of these blends compared to that of traditional mixed-metal stabilizers.     

Mechanical properties of sisal natural fiber composites according to strain rate and absorption ratio

The effects of strain rate and water absorption properties can be used to evaluate the environmental degradation of sisal fiber reinforced polymer–matrix composites. Composites of vinylester and epoxy resin, reinforced by sisal fiber, were manufactured using the RTM method. To examine how the mechanical properties change with different surface treatments of a fiber, three fibrous composites with nontreated, permanganate, and silane treatments were compared in this experiment. Material fracture occurred as the brittleness hardened due to an increase in strain rate. The tensile strength was the largest in the permanganate‐treated epoxy composites, while the untreated vinylester had high elongation and fracture energy. The highest tensile strength value occurred at a 30% absorption ratio. POLYM. COMPOS., © 2011 Society of Plastics Engineers.     

Fabrication of an Inductively Coupled Plasma Antenna in Low Temperature Co‐Fired Ceramic

A miniature electrostatic thruster is being developed in Low Temperature Co‐fired Ceramic (LTCC) at Boise State University. The thruster is composed of an antenna to create the plasma, a cylinder to contain the plasma, and grids to extract the plasma beam at high velocity. In this work, the development of the inductively coupled plasma (ICP) antenna in LTCC will be presented. This antenna is fabricated using DuPont 951 LTCC tape. A Direct Write dispenser is used to apply silver paste for the spiral ICP antenna. Using LTCC allows for the antenna to be embedded in the device under a thin sheet of LTCC dielectric, which protects the antenna from ion back bombardment during operation. This thin sheet is the seventh layer of the total device, with the ICP antenna one layer below the top. The design of the antenna is based on the research done by J. Hopwood. This article discusses the fabrication and performance of the ICP antennas in LTCC. These ICP antennas are operated at pressures from 10 mTorr to 1 Torr with radio frequencies (RF) of 500 MHz to 1 GHz to inductively couple with low‐pressure argon to produce plasma. The performance of the antennas will be verified with data showing the start and stop power of the plasma at various pressures and an electric field map of the RF field above the antenna.     

Mechanical- and Physical-Property Changes of Neutron-Irradiated Chemical-Vapor-Deposited Silicon Carbide

Indentation and density measurements have revealed important changes in the mechanical and physical properties of silicon carbide (SiC) due to neutron irradiation. Specifically, the changes in the elastic modulus, hardness, fracture toughness, and density with irradiation have provided an understanding of the expected performance of SiC and SiC composites in nuclear applications. After the accumulated damage has saturated, these mechanical properties were affected primarily by the irradiation temperature. Chemical-vapor-deposited (CVD) SiC was irradiated above the saturation fluence and yielded volumetric swelling of 2.6% and 1.3% for irradiation temperatures of 100°-150°C and 500°-550°C, respectively. At the same respective temperatures, the elastic modulus decreased from an unirradiated value of 503 GPa to ∼420 and 450 GPa. Conversely, the hardness increased from 36 GPa for the unirradiated CVD SiC to 38 and 40 GPa for the samples irradiated at 100°-150°C and 500°-550°C, respectively. Interestingly, these two independent properties approached almost-constant levels after exposure to a fluence of 0.5 × 10²⁵ n/m², E > 0.1 MeV. Indentation fracture toughness measurements, which were within the range of values in the literature for conventional fracture toughness procedures for SiC, increased from ∼2.8 MPa·m^1/2 for the unirradiated samples to 3.7 and 4.2 MPa·m^1/2 for the samples that were irradiated at 100°-150°C and 500°-550°C, respectively.     

Dehydration of 2‐methylbutanal to isoprene using aluminium phosphate catalysts

The synthesis of isoprene from the dehydration of 2methylbutanal is described using aluminium phosphates as catalysts. Two samples of aluminium phosphate are studied prepared from the reaction of phosphoric acid with aluminium chloride or sulphate. The chloride route gives a mixed cristobalite/tridymite AlPO₄ and this is shown to be more active than a catalyst containing only the tridymite form of AlPO₄ formed from the sulphate route. The AlPO₄ catalysts are also shown to be active catalysts for the synthesis of isoprene from 3methylbutan2one, which is the major byproduct formed from the reaction of 2methylbutanal. The AlPO₄ catalysts are deactivated due to the deposition of coke in addition to loss of phosphorus from the surface. Catalytic activity can be totally restored by a simple calcination procedure at 800°C.     

钛合金叶片坯料的响应面(RSM)优化方法

生产高质量的钛合金叶片设计是关键。提出了将响应面法(ResponseSurfaceMethod,RSM)和数值模拟(Finite element method,FEM)相结合以优化叶片类锻件用坯料的方法,详细描述了该方法的求解过程,构造了表征叶片各部分应变和温度均匀性的函数。将此方法应用于带阻尼台的钛合金风扇叶片预成形坯料的优化,确定出了最优坯料的形状。用该方法确定出的最优坯料能得到满意的成形效果和组织均匀性。     

Two-Dimensional thermal analysis of resistance welded thermoplastic composites

A transient two-dimensional thermal model for resistance welding of thermoplastic composites is presented. A parametric study is conducted that yields insight into the welding process enabling some critical process and material parameters to be identified. Time to melt is predicted by the model and is successfully compared to experimental observations. Local heating and meltthrough can also be explained by the transient thermal model in agreement with experimental observations. Mode I fracture toughness of unidirectional graphite reinforced poly(etheretherketone) resistance welded double cantilever beam specimens are conducted under various process conditions. Experimental results indicate that under optimum process conditions, the interlaminar fracture toughness of the bulk compression-molded thermoplastic composite material can be achieved using resistance heating as a joining technique.     

Perchlorate removal in aqueous solutions using periodic mesoporous organosilicas (PMOs) functionalized with quaternary ammonium groups

Perchlorate anion (ClO₄⁻) in water has become an environmental issue of concern because it can impair proper functioning of the thyroid gland. For the removal of perchlorate anions from water, adsorption using anionexchange resins has been generally used as the most suitable method. In this work, we prepared periodic mesoporous organosilica materials (PMOs) functionalized with quaternary ammonium ligands, and used them for the removal of perchlorate anions from aqueous solutions. The physical and chemical properties of prepared samples were measured using nitrogen adsorption-desorption measurement, elemental analyses, X-ray diffractometer, and infrared spectrometer. We also investigated equilibrium isotherms for the measurement of adsorption capacities and kinetic performance of the prepared samples.     

Drying characteristics of sewage sludge

To obtain the drying rate of sewage sludge for use in design of a conductive indirect-heating dryer with agitation, the drying characteristics of sewage sludge from three different wastewater treatment plants were investigated with a thermogravimetric analyzer (TGA) in isothermal conditions. Temperature and sample mass were considered as experimental variables. The drying mechanism agreed well with the shrinking core model dominated by the kinetic rate. The activation energy of drying was 17.30 kJ/g mol. A rate equation was proposed for drying of sewage sludge.     

Research on the effects of disconfirmed client role expectations in psychotherapy: A critical review.

Critically examines the pervasive assumption found in psychotherapy literature that disconfirmation of client role expectations has been demonstrated to be a negative influence in psychotherapy. When the empirical literature is examined, this hypothesis does not appear to be as conclusive as has been suggested. In fact, the empirical studies are evenly divided in supporting this hypothesis. The ambiguous state of the research is discussed in terms of problems in design and conceptualization: (a) The operationalization of the independent variable has often been inadequately precise or reliable. (b) The definition of expectation has usually not been clearly specified. (c) The theoretical base for almost all of the research may not be appropriate for the kinds of affectively toned expectations in psychotherapy. Future research should incorporate procedures to counter these types of problems. (72 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)