Effect of a poly(dimethylsiloxane) modified polyolefin additive on the processing and surface properties of LLDPE

A polydimethylsiloxane (PDMS) modified polyolefin (obtained by reacting an ethylene‐ethyl acrylate‐maleic anhydride (EEAMA) copolymer with an amine terminated PDMS in the melt phase) was used as a processing aid to facilitate the extrusion of linear low density polyethylene (LLDPE). In blends of LLDPE and PDMS modified polyolefin (PMPO), apparent viscosity and shear stress at the die wall are reduced in comparison to pure LLDPE, and extrusion instabilities are delayed as evidenced by the fact that extrudate surface roughness only occurs at higher shear rates when the additive is present. A higher PDMS content in the PMPO leads to a more pronounced delay of extrusion instabilities. Single‐screw extrusion of LLDPE compounds with a PMPO results in nearly doubled throughput per unit input energy. The reduction of viscosity and improvements in extrudate quality are attributed to the decreasing surface free energy of the PMPO with an increasing PDMS content, as determined by contact angle measurements. Chemical composition analysis of the extrudate surface and cross‐section reveals silicon enrichment at the surface. The friction coefficients of pure PMPO and PMPO/LLDPE blends are measured and found to decrease as a result of the presence of PDMS. POLYM. ENG. SCI., 47:1309–1316, 2007. © 2007 Society of Plastics Engineers     

Usability of product X-lessons from a real product

Using the example of a real product, this paper shows how various usability assessments, conducted by different human factors engineers, in several phases of the product's development life-cycle, identified similar potential usability problems. Circumstances dictated that no remedial action was taken, so it was possible to track these potential usability defects to customer sites, where it was found that most of the important problems did indeed occur. Thus, it can be demonstrated that human factors advice was valid and reliable. In simpler terms, early usability evaluation by human factors engineers can save hours of wasted development effort and customer frustration, and can help to ensure that a more usable product is produced.     

Neocuproine, a selective Cu(I) chelator, and the relaxation of rat vascular smooth muscle by S-nitrosothiols

1. A study has been made of the effect of neocuproine, a specific Cu(I) chelator, on vasodilator responses of rat isolated perfused tail artery to two nitrosothiols: S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and S-nitroso-glutathione (GSNO). 2. Bolus injections (10 microl) of SNAP or GSNO (10(-7)-10(-3) M) were delivered into the lumen of perfused vessels pre-contracted with sufficient phenylephrine (1-7 microM) to develop pressures of 100-120 mmHg. Two kinds of experiment were made: SNAP and GSNO were either (a) pre-mixed with neocuproine (10(-4) M) and then injected into arteries; or (b) vessels were continuously perfused with neocuproine (10(-5) M) and then injected with either pure SNAP or GSNO. 3. In each case, neocuproine significantly attenuated vasodilator responses to both nitrosothiols, although the nature of the inhibitory effect differed in the two types of experiment. We conclude that the ability of exogenous nitrosothiols to relax vascular smooth muscle in our ex vivo model is dependent upon a Cu(I) catalyzed process. Evidence is presented which suggests that a similar Cu(I)-dependent mechanism is responsible for the release of NO from endogenous nitrosothiols and that this process may assist in maintaining vasodilator tone in vivo.     

NMR analysis of butyl acrylate/methylmethacrylate/α‐methyl styrene terpolymers

Composition analysis for butyl acrylate (BA)/ methyl methacrylate (MMA)/α‐methyl styrene terpolymers was carried out by NMR spectroscopy methods. ¹H‐NMR was used primarily for this analysis, but because the method did not provide independent measurements for the BA and MMA fractions, the terpolymer composition analysis was open to higher than normal levels of uncertainty. Supplementary analyses were made with quantitative ¹³C‐NMR methods to confirm the results from ¹H‐NMR (quantitative ¹³C‐NMR was used to provide corroboration of selected composition analyses). To confirm spectral assignments in the ¹H‐ and ¹³C‐NMR spectra, heteronuclear multiple quantum coherence and J Modulated Spin Echo (JMOD) pulse sequences were used. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2093–2098, 2007     

Integrated appraisal of a Solar Hot Water system

An ‘integrated appraisal’ of a solar hot water (SHW) system in the UK residential sector was carried out to assess its overall energetic, environmental and economic performance. The energy analysis indicates that when displacing a gas boiler, oil boiler, or electrical immersion heater, the SHW system would provide a net energy benefit for the majority of its estimated 25 year lifetime, thus enhancing energy security by reducing the use of, and dependence upon, conventional energy resources (mainly fossil fuels). A life cycle assessment was carried out to determine a range of environmental implications of installing and using the SHW system. It was shown that the use of aluminium has the greatest impact within the production of the system. During its use, the SHW provides the largest environmental externality benefits when displacing electricity. The economic assessment indicates that the SHW system is currently uncompetitive given the negative net present values of the various scenarios assessed. This outcome included the internalisation of the social costs of carbon. There are, however, future prospects for reduced capital costs that may significantly improve the economic performance of the system.