Copolyester studies. I. Preparation and characterization of tetramethylene terephthalate–tetramethylene sebacate copolymers

Tetramethylene terephthalate–tetramethylene sebacate copolymers containing up to 20 mol % sebacate have been prepared and characterized. Molecular weights and distributions have been evaluated using viscometry and gel-permeation chromatography. Compositions have been established by NMR spectroscopy. Thermal properties have been studied by differential scanning calorimetry and dynamic mechanical methods. Melting and glass-transition temperatures and moduli are discussed in terms of the structural differences, particularly the effect of composition on chain flexibility. Density and thermal methods of crystallinity determination are critically discussed for these systems.     

Thermal degradation of polymers. X. Thermal analysis studies on poly(p-N,N-dimethylaminostyrene) homopolymers and copolymers with styrene in nitrogen

Studies have been made on the effect of the molecular weight of p-N,N-dimethylaminostyrene homopolymers and the composition of its copolymers with styrene on the glass transition temperature. Comparative thermal degradation studies have been made on polystyrene and p-N,N-dimethylaminostyrene polymers by thermal analytical methods (TG, DTA, and DSC). The differences in thermal stability and overall thermal degradation behavior of the two systems are discussed in terms of the differences in their degradation mechanisms.     

Solubility of gases in a hydroformylation solvent

The solubility of reactants used in homogeneously catalyzed hydroformylation of alkene was studied in a pressurized, semi-batch autoclave. The solubilities of alkene, carbon monoxide and hydrogen in the 2,2,4-trimethyl-1,3-pentanediol mono(2-methylpropanoate) solvent (NX 795) were determined by precise pressure and weight measurements. The measured solubilities were tested against empirical and theoretical models. Logarithmic empirical models gave a very good fit to experimental solubility data. To obtain nonempirical equations for the gas solubility, thermodynamic models based on activity coefficients and equations of state were used. The activity coefficient models based on regular solution theory (RST) predicted the solubilities well, but the selection of the model is the critical issue. For 1-butene, the best prediction was provided by the Yen and McKetta modification of the RST, whereas for carbon monoxide and hydrogen it was necessary to include a mixing entropy term in the RST. The Soave-Redlich-Kwong equation of state gave a fairly good prediction of the solubilities, but not as good as the RST-based models.     

Using multiple endmember spectral mixture analysis to retrieve subpixel fire properties from MODIS

The Moderate-Resolution Imaging Spectroradiometer (MODIS) sensors on NASA's Terra and Aqua satellites image most of the Earth multiple times each day, providing useful data on fires that cannot be practically acquired using other means. Unfortunately, current fire products from MODIS and other sensors leave large uncertainties in measurements of fire sizes and temperatures, which strongly influence how fires spread, the amount and chemistry of their gas and aerosol emissions, and their impacts on ecosystems. In this study, we use multiple endmember spectral mixture analysis (MESMA) to retrieve subpixel fire sizes and temperatures from MODIS, possibly overcoming some limitations of existing methods for characterizing fire intensities such as estimating the fire radiative power (FRP). MESMA is evaluated using data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) to assess the performance of FRP and MESMA retrievals of fire properties from a simultaneously acquired MODIS image, for a complex of fires in Ukraine from August 21, 2002. The MESMA retrievals of fire size described in this paper show a slightly stronger correlation than FRP does to fire pixel counts from the coincident ASTER image. Prior to this work, few studies, if any, had used MESMA for retrieving fire properties from a broad-band sensor like MODIS, or compared MESMA to higher-resolution fire data or other measures of fire properties like FRP. In the future, MESMA retrievals could be useful for fire spread modeling and forecasting, reducing hazards that fires pose to property and health, and enhancing scientific understanding of fires and their effects on ecosystems and atmospheric composition.     

Examining working memory load and congruency effects on affordances and conventions

Although there is a debate about whether designers should draw a distinction between perceptual affordances and cultural conventions, there are few behavioral studies. We examined the impact of working memory load and expected button-to-action mapping congruency on affordances and conventions. The findings suggest both sides of the debate are correct. Learned conventions were found to structure responses towards expected actions, just like affordances, but affordance-based interactions were not affected by memory load while convention-based actions were. Therefore, designers ought to employ perceptual affordances when possible and when not feasible they ought to reuse established conventions. Additionally, evidence is presented that violating expected affordance-based and convention-based button-to-action mappings caused a similar performance cost. We believe that after the initial learning period, conventions play a critical role in the perception of a design’s available actions just as perceptual affordances do.     

In search of the elite: revising a model of adaptive emulation with evidence from benchmarking team

We revise Strang and Macy's model of adaptive emulation throughinspection of empirical efforts at innovation. Self-reportsof managers participating in benchmarking teams are consistentwith the argument that innovation is problem-driven, focusedon performance and draws heavily on success stories. But managerialaccounts also indicate close attention to prestigious firms,an orientation that broadens prior arguments about imitationof top performers. We develop a version of adaptive emulationwhere firms imitate members of a corporate élite whoseprestige is related to but not reducible to performance. Computationalmodeling indicates that socially oriented emulation is collectivelyadaptive but that it also widens the range of innovations thatexperience faddish careers.     

德国钢铁工业空气质量控制

到目前为止,在德国管理钢铁公司空气质量控制工作发展的主要管理文件是联邦排放物控制法及关于空气质量控制的补充技术说明(TA Luft).TA Luft法规,最近于2002年进行了修订,具体包括从预防角度而明确设立的总的及与工厂有关的排放限度,排放目标和将现存的工厂升级到目前技术水平的时间限制.这些条款由许多联邦州的政府当局统一执行,已经使德国全国范围的空气质量控制几乎同时达到一个高水平.报告描述了德国钢铁工业和Duisburg地区Thyssenkrupp Stahl的结构性发展,以及在该地区已生效的相关空气质量控制措施.具有里程碑意义的事件包括生产方法的变化,吹氧工艺的引入,辅助除尘技术的应用和一致推广,CO2排放控制工作和一些方面的发展(如炼焦技术方面).为控制PCDD/PCDF排放而进行的吸附基烧结厂废气净化及含铁残余物如沉积粉尘、污泥的处理.到目前为止已获得的多层经验,既有肯定的也有否定的,指出需要加强技术和管理方面的国际合作.     

Thermal degradation of polymers. VIII. Ablation studies on a series of fiber-reinforced phenolic resin composites

The use of a laboratory ablation test rig for the assessment of tubular fiber-reinforced composites is described. Ablation resistance, char depth, smoke, and flash measurements have been made on a series of composites based on a standard phenol–formaldehyde resin incorporating various fibrous reinforcing agents. The results have been compared with those obtained from a standard asbestos-reinforced composite prepared from the same resin. Results are discussed in terms of the properties of the composite and of the fibrous reinforcing agent.     

Thermal degradation of polymers. XV. Vacuum pyrolysis studies on poly(p-methoxystyrene) and poly(p-hydroxystyrene)

The monomers p-hydroxystyrene (p-HS) and p-methoxystyrene (p-MS) have been synthesized and polymerized using azobisisobutyronitrile as free-radical initiator. The polymerization behavior of p-HS is anomalous, and a mechanism is suggested to account for this phenomenon. Poly(p-hydroxystyrene) (PHS) and poly(p-methoxystyrene) (PMS) homopolymers have been subjected to vacuum pyrolysis at temperatures in the range of 300–500°C. The products of degradation have been identified and qualitatively and quantitatively analyzed and the degradation behavior of the two systems compared with polystyrene. PHS shows anomalous behavior resulting from the high reactivity of the p-HS monomer and the facility for transfer afforded by the proton of the hydroxyl substituent. Mechanisms to account for the degradation behavior of each system are discussed.     

Thermal degradation of polymers. XIV. Thermal analysis studies in air on homopolymers of m-N,N-dimethylaminostyrene and p-N,N-diethylaminostyrene and their copolymers with styrene

Homopolymers of m-N,N-diethylaminostyrene and p-N,N-diethylaminostyrene and their copolymers with styrene have been subjected to thermal analysis studies in air. Molecular weight and copolymer composition have been shown to influence the stability of the polymers and the shape of the TG and DSC curves in the case of polymers containing m-N,N-dimethylaminostyrene. Polymers containing p-N,N-diethylaminostyrene show TG and DSC curves essentially independent of molecular weight and copolymer composition. The behavior of the two systems is discussed in terms of the antioxidant effect of the chain-bound N,N-dialkylamino substituents and their secondary reactions.