Synthesis and thermal dissociation of phenol- and naphthol-blocked diisocyanates

Phenol-, 2-naphthol-, and 1-nitroso-2-naphthol-blocked toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI) adducts and their polymers with PPG-1000 were prepared and characterized by nitrogen estimation, IR, and ¹H-NMR spectroscopy. The absence of an IR absorption band at 2270 cm^?1 confirmed the completion of the reaction between the isocyanate and the blocking agents, whereas the presence of a band at 1075–1150 cm^?1 confirmed the formation of poly(ether urethanes). The deblocking temperatures were determined by the use of DSC and by the carbon dioxide evolution methods. The thermal stabilities of the 2-naphthol-blocked diisocyanates were less than the phenol-blocked diisocyanates. Dissociation temperature was also reduced by the nitroso group in the blocking agent. Mass spectral data confirmed the product analysis. The solubility of the adducts were determined in the different polyols. Adducts based on IPDI showed better solubility than did those based on TDI. © 1994 John Wiley & Sons, Inc.     

Amarillo Yard Art: Resident Responses to Yard Signs and Their Regulation

In the City of Amarillo, Texas, more than 5,000 objects of a unique form of art—yard signs—are located on individual properties. We used a windshield survey to identify 2,311 such signs and sent questionnaires to a random selection of 394 residents with the signs and 696 of their neighbors. We asked how often they encountered the signs and their opinions of them and also solicited background information. Most residents with no sign in their yard evaluated the signs negatively. The findings suggest popular support for design control over this one kind of public art in residential yards. The signs and residents' responses to them bring to the fore some questions relating to the conflict between design controls and property rights and freedom of speech. Communities with similar conflicts should consider controls of location and physical features, citywide or on a block-by-block basis, and use a proactive approach.     

Polyurethane Solvent-Based Adhesives for Footwear Applications

Polyurethane solvent-based adhesives with and without tackifier having different solid contents were prepared. Viscosity of adhesives was found to increase with increasing resin content. Peel strengths of adhesives before and after aging were measured on PVC-Leather substrates and TPR-Leather substrates. It is found that the tackifier improves the adhesive strength of the polyurethane. In the case of TPR-Leather substrates all adhesives give good performance immediately on application of adhesive whereas in the case of PVC-Leather substrates good results are achieved only after 24 hrs of application. Shelf-life of the adhesives is found to be 6 to 12 months.     

Mechanism of Phase Formation in Pb(ZrxTi1–x)O3 Synthesized by a Partial Oxalate Method

The phase formation mechanism, as well as the morpho-tropic phase boundary, of lead zirconate titanate (PZT) processed by a partial oxalate method was investigated by simultaneous thermal analysis (TG-DTA) and by qualitative and quantitative X-ray diffraction (XRD). The results show that the Zr_xTi_1–xO₂ (ZT) phase reacts with PbO forming the PZT phase without intermediate phases. XRD analysis showed the coexistence of rhombohedral and tetragonal phases for 0.47 ≤ x ≤ 0.55 with the phase boundary composition for x = 0.51. For low calcination temperatures, preferential formation of the PZT rhombohedral phase was observed. A model for phase formation of PZT by the partial oxalate method is proposed based on the existence of two interfaces of reaction (PbO-PZT and PZT-ZT) and diffusion of cations.     

Landscape mirror: the attractiveness of reflecting water

This research examined human preference for water and a key aspect of water, its reflection. We compared responses to reflection in water versus reflection in glass and responses to reflection versus transparency. Sixty respondents rated the attractiveness of four scale-models varied on those dimensions. High inter-item reliability across the rating scales called for their combination into a composite measure of attractiveness. The analysis revealed that individuals preferred the water to the glass and the reflective to the transparent surface. They gave the most favorable ratings to the scene with reflective water, suggesting the potential desirability of reflective ponds as a design element.     

Analysis of fields and forces in a permanent magnet linearsynchronous machine based on the concept of magnetic charge

Two-dimensional and three-dimensional field distributions produced by permanent magnets (PMs) of a permanent-magnet linear synchronous motor (PMLSM) are obtained in analytical forms, based on the concept of magnetic charge and the method of images. The determination of electromagnetic forces and parameters of this type of a motor is examined. The proposed method and the resulting simplified formulas are useful for the design and analysis of PMLSMs as well as for other types of PM motors. Calculated results compare favorably with the experimental results, and thus validate the assumptions and the analysis     

A fully digital control strategy for synchronous reluctance motorservo drives

For existing electric drives, the controller implementation is either totally analog or hybrid analog/digital, and the control algorithm broadly falls into two categories, average torque control (ATC) and instantaneous torque control (InsTC). In this paper, a fully digital-implementation oriented control strategy-incremental torque control (IncTC)-is proposed and verified with digital simulation. A TMS320C30 DSP-based implementation of the proposed IncTC is developed and tested. Experimental results given in the paper indicate that the proposed IncTC is valid and holds a great promise for reluctance motor digital control     

Synthesis and characterization of poly(urethane‐co‐imidine)s having pendent phenyl and benzylidene groups using bisphthalides,bislactones and blocked polyurethane prepolymers

Poly(urethane‐co‐imidine)s were prepared using amine blocked polyurethane (PU) prepolymer. The PU prepolymer was prepared by the reaction of poly(propylene glycol) (PPG₂₀₀₀) and 2,4‐tolylene diisocyanate (TDI) and end capped with N‐methyl aniline. The PU prepolymer was then reacted with bisphthalides and bislactones, until the evolution of carbon dioxide ceased. Polymerization reactions with bispthalides and bislactone took more time than with dianhydrides. Polymers were characterized by FTIR, GPC, TG and DSC analyses. Molecular weights of the poly(urethane‐co‐imidine)s were found to be lower than that of poly(urethane‐co‐imide)s. Compared to poly(urethane‐co‐imide)s all poly(urethane‐co‐imidine)s showed high glass transition temperature and crystallization peak in DSC. The thermal stability of the polyurethanes was found to increase with the introduction of imidine component. © 2001 Society of Chemical Industry     

On the study of electrical conductivity of polycrystalline cadmium telluride

The complex impedance of polycrystalline cadmium telluride has been measured as a function of frequency by a two-probe technique. The experimental data measured in the temperature range 301–565 K have been analyzed in the complex plane formalism and suitable equivalent circuits have been proposed in different temperature regions. The values of resistance and capacitance of bulk and grain boundary contributions have also been independently calculated from the Debye peak of spectroscopic plots. The role of bulk and grain boundary in the overall conduction process have been discussed with realistic justification.     

Fields, forces, and performance equations of air-core linerself-synchronous motor with rectangular current control

An analytical field approach to determine the permanent magnetic field distribution in a flat air-core self-synchronous linear motor with a permanent magnet mover is reported. Thrust and normal forces are calculated for idealized rectangular-current inverter control. Notable thrust and normal force time pulsations are shown through a numerical example. The performance equations with an on-off current controller are developed with the motor fed from a voltage source transistor inverter. The analysis represents a reliable tool for refined design and control of permanent magnet air-core linear self-synchronous motors