Synthesis and Characterization of Allyl Fatty Acid Derivatives as Reactive Coalescing Agents for Latexes

This work evaluated the use of allyl fatty acid esters derived from vegetable oil (palmitic acid, soybean and sunflower oils) as reactive coalescing agents in a waterborne latex system. Allyl fatty acid derivatives (AFAD) from vegetable oils were synthesized by two different processes. The synthesis was monitored by IR-spectroscopy and the final product characterized by FT-IR, GC–MS, ¹H and ¹³C NMR. The presence of conjugated double bonds in the aliphatic chain was confirmed, which is a determinant for the proposed autoxidative latexes drying mechanism. Each of the AFAD were subsequently added to a standard acrylic emulsion, in order to study its potential as reactive coalescing agent. The minimum film-forming temperature (MFT), glass transition temperature (T _g), drying time and rubbing resistance to solvents were evaluated. The results showed that, when added to water-borne acrylic resins, an AFAD acts as a non-volatile plasticizer capable of autoxidative crosslinking with itself.     

Enhanced Performance of Nanostructured Coatings for Drilling by Droplet Elimination

Cutting tool performance is mainly characterized by material substrate, cutting edge geometry, and coating, and also by a good choice of the cutting parameters, mainly cutting speed, depth of cut, and feed. In drilling a good choice of substrate/coating can reduce production costs per hole cut by 50%. Coatings evolution has gone from monolayer to nanostructured and/or nanometric-scale multilayer coatings. These are used because of their high hardness, good corrosion and oxidation resistance, and thermal stability. Cutting edge preparation on the one hand and droplet elimination after the coating process on the other are important issues for reaching a good tool/coating performance, being a key issue. In this article a series of coatings for drilling low and medium carbon alloyed steels are presented, along with their performance. Validation tests were carried out on steel 42CrMo4, very often used in the automotive sector. Seven coatings were tested, including AlCrSiN, µAlTiN, TiAlCrN, AlTiCrN, AlCrN, AlTiSiN, and TiAlSiN. Flank wear, evolution of drilling thrust force and torque, damage on cutting edge faces on primary cutting edge, and behavior of drill bit secondary edges were studied. A final elimination of droplets by drag grinding was performed in several cases. Process monitoring, scanning electron microscope (SEM) microscopy, and energy-dispersive X-ray (EDX) analysis were used, concluding that the best results were for µAlTiN, TiAlSiN, and AlTiSiN. Reasons for the good behavior are the good surface finishing after droplet elimination and the high thermal stability of these protective layers.     

Dynamical behaviour of the optical properties of photopolymers and the lorentz-Lorenz formula

Abstract

Photochemical variations of the refraction index of dielectrics are explored using the Lorentz-Lorenz formula. The scope of this analysis is restricted to photoinitated chemical reactions in the optical range that originates small differences in the refraction index, assuming that the dielectric constitutes an approximately constant background. These types of systems are relevant when considering the optical macroscopic response of holographic recording materials. Relations arising from a photopolymer are analysed in detail.     

Time series of scientific growth in Spanish doctoral theses (1848–2009)

This article analyses scientific growth time series using data for Spanish doctoral theses from 1848 to 2009, retrieved from national databases and an in-depth archive search. Data are classified into subseries by historical periods. The analytical techniques employed range from visual analysis of deterministic graphs to curve-fitting with exponential smoothing and AutoRegressive Integrated Moving Average models. Forecasts are made using the best model. The main finding is that Spanish output of doctoral theses appears to fit a quasi-logistic growth model in line with Price’s predictions. An additional control variable termed year-on-year General Welfare is shown to modulate scientific growth, especially in the historical period from 1899 to 1939.     

Entrepreneurial quality and regional development: Characterizing SME sectors in low income areas*

This paper analyses the characteristics of SMEs in less‐developed areas in comparison with more advanced economies. The conceptual framework includes different factors making up the so‐called ‘entrepreneurial quality’ of the SME sector: the personal characteristics of the entrepreneurs (motivations and previous experience), different dimensions of the SMEs’ entrepreneurial orientation, and the patterns of the SMEs’ insertion in national and global value chains. The empirical analysis uses data of SMEs in four different Spanish provinces representing examples of low income economies and comparatively high income ones, respectively. Results show the SMEs in the low income economies to be characterized by a lower entrepreneurial quality.