The thermal degradation of acrylic pressure-sensitive adhesives based on butyl acrylate and acrylic acid

The thermal degradation of acrylic pressure-sensitive adhesives at 250 °C was investigated using pyrolysis-gas chromatography. Knowledge of the types and amounts of pyrolysis products will provide important information on the thermal degradation of acrylic adhesives and the mechanisms involved. Unsaturated monomers including butyl acrylate and butyl methacrylate were formed during thermal degradation of butyl acrylate–acrylic acid copolymers. As a result of side chain reactions in the thermal destruction of the butyl acrylate–acrylic acid-based self-adhesives, a remarkable amount of butyl alcohol was produced. The unsaturated monomers formed as a result of thermal degradation could potentially be used in a new polymerization process.     

Redesigning an assembly line through lean manufacturing tools

The implementation of a lean manufacturing strategy represents a robust contribution to the phase sequence that leads to operational excellence and the continuous improvement through the elimination of nonvalue-added activities. Therefore, lean practices contribute substantially to plant operational performance. This paper studies the use of value stream mapping (VSM) as a tool in lean manufacturing implementation and a framework of improvement activities, in particular for an efficient introduction of kanban and milkrun techniques. A case study illustrates VSM use, as well as kanban and milkrun systems application on an assembly line. Finally, the results obtained show the path of improvement, measured through the lean rate (LR) and dock-to-dock time (DtD).     

Factors affecting the adsorption of stabilisers on to carbon black (flow micro-calorimetry studies) Part II Hindered amine light stabilisers (HALS)

The interaction of hindered piperidine light stabilisers (HALS) with carbon black has been examined using flow micro-calorimetry (FMC) and Fourier transform infrared spectroscopy (FTIR). Significant differences in both the overall adsorption activity and molar heats of probe adsorption are observed. Differences in adsorption behaviour between different types of carbon black were clearly evident and, as with a previous paper (see reference 1, in the latter paper, surface chemistry of the carbon blacks investigated is extensively analysed by XPS, FTIR, N₂ BET adsorption and Karl–Fischer analysis), were mainly to be due to differences in carbon black surface chemistry. The specific surface area merely physically affected the level and heat of adsorption (per unit mass of carbon black). Variation in the degree of substitution of the piperidine amine is an important factor that is found to influence the adsorption activity of HALS, as well as the number of adsorption active and sterically accessible functional groups per HALS molecule. In some cases the adsorbed HALS could be detected by FTIR; shifts in absorption frequencies associated with both the adsorbate and the substrate yielded significant insight into the mode of adsorption of several of the HALS investigated.     

Kinetic study of the redox process for separating and storing hydrogen: Oxidation stage and ageing of solid

The behaviour of an iron oxide sample (Fe₂O₃) during successive reduction–oxidation cycles (steam–iron process) has been investigated by means of a thermobalance system acting as a differential reactor.The Johnson–Mehl–Avrami–Kolmogorov (JMAK) model, based on nucleation and growth mechanisms, has been used to describe the individual reoxidation processes as well as to predict the stability of the oxide after a high number of redox cycles.The effect of temperature, steam partial pressure and oxidation length has been discussed.The experimental results, as well as the parameters for the JMAK model, show that there is no significant effect of the temperature and the steam partial pressure used in the oxidation stages on the behaviour of the subsequent cycles (taking apart the first one). This conclusion applies also to the length of the oxidation period, if for such variable a value above a given threshold is used, which could be theoretically foreseen.     

Assessment of olive cake as soil amendment for the controlled release of triazine herbicides

Organic matter-rich agricultural by-products are being produced in huge quantities and can be applied to soil as a disposal strategy. The application of two different rates (2 and 8% w/w) of olive cake to a Mediterranean calcareous soil resulted in an increased sorption of four triazine herbicides, which was higher for the more hydrophobic compounds (terbuthylazine and prometryn) and lower for the more polar ones (simazine and cyanazine). However, when the sorption coefficients were normalised to the total soil organic carbon (K(oc)), the results did not significantly differ between simazine and cyanazine which is an indication that the olive cake did not exert different sorption capacity for both compounds. On the contrary, K(oc) values for terbuthylazine and prometryn increased in the amended soils. Our results from experiments using mixtures of several pesticides suggest that competition for sorption sites resulted in a decrease of herbicide sorption. Desorption was hysteretical both for the amended and unamended soils, but the addition of olive cake at the highest dose diminished desorption of most of the herbicides. In conclusion, the addition of olive cake behaves as a promising method for reducing the risk of groundwater pollution by pesticides.     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

Modelling of mass loss of char particles during combustion in flow of inert material

The inspiration for this research was an attempt at the numerical simulation of the process of mass loss of char particles during its combustion in the upper zone of a CFB boiler furnace. In the first part of the research an experiment was carried out, during which singular char particles were burned in a flow of heated sand. During the course of this test manually polished spherical particles chosen from arbitrary real coal particles were used whose diameter amounted to 10 mm. The mass loss of burning particles was recorded with a tensometric branch scale. The measuring equipment applied enabled the observation of the mass loss both as a result of combustion and erosion resulting from the contact of inert material accelerated particles with the upper surface of the motionless particle being tested. The results of the experiment were compared with the results of numerical simulation, where for the first time the mass loss of a coal particle was presented as the superposition of two separate processes i.e. combustion and surface erosion. The values obtained indicated a good level of conformity which may illustrate the possibility of applying this model in real conditions.     

Effects of international collaboration and status of journal on impact of papers

This study examines the effect of international collaboration of Slovenian authors and the status of journals where papers are published (as determined by their impact factors) on the impact of papers as measured by the number of citations papers receive. Research programme groups working in Slovenia in the 2004–2008 period in the fields of physics, chemistry, biology, biotechnology, and medical science were used for analyses. The results of the analyses show that the effects of the two factors differ among the fields. We discuss possible reasons for this, including the possibility that differences are the result of Slovenia’s science policy.     

Crystalline and magnetic properties of Er and Yb chromites modified by Mn and Ca cations

The structural and physical properties of some chromites–manganites solid solutions (RE,Ca)Cr_0.5Mn_0.5O₃, RE = Er, Yb, have been studied by X-ray diffraction and magnetic measurements. Powders were prepared by solid state reaction between the component oxides. Complete solid solutions were obtained, except for YbCr_0.5Mn_0.5O₃ in which traces of hexagonal YbMnO₃ remain through all the synthesis and sintering processes. Incorporation of Mn³⁺ cations does not alter the perovskite O-type structure of the chromites. Ca-containing solid solutions maintain the O-type structure.Magnetic measurements indicate an increase of the ferromagnetic behavior when Ca²⁺ is incorporated into the lattice, with an expected transformation of Mn³⁺ into Mn⁴⁺, and its associated ferromagnetic exchange interactions. Competition between ferromagnetic Mn³⁺–Mn⁴⁺, Mn³⁺–Cr³⁺ and antiferromagnetic Cr³⁺–Mn⁴⁺, Yb–TM interactions (TM: transition metal) leads to complex magnetic ordering in the ytterbium chromites, although double exchange Mn³⁺–Mn⁴⁺ interactions predominate and suppress the spin reversal expected for the pure YbCrO₃ material.