Plastisol Gelation and Fusion Rheological Aspects

This study deals with the rheological aspects of poly-vinyl chloride (PVC) plastisol gelation and fusion processes in foamable formulations. Here, such processes are simulated by temperature-programmed experiment (5 K min−1) in which complex viscosity components are continuously recorded. Nineteen samples based on a PVC-VAC (vinyl acetate 95/5) copolymer with 100 phr plasticizer have been studied, differing only by the plasticizer structure. The sample shear modulus increases continuously with temperature until a maximum, long time after the end of the dissolution process as characterized by DSC. The temperature at the maximum varies between 345 and 428 K with a clear tendency to increase almost linearly with the plasticizer molar mass, and to vary with the flexibility and the degree of branching of the plasticizer molecule. The shear modulus increase is interpreted in terms of progressive “welding” of swelled particles by polymer chain reptation. The plasticizer nature would mainly affect the friction parameter of chain diffusio

Kinetic Model for Micro Algae Cell Concentration and Size Distribution: Application to Nannochloropsis gaditana

The cell concentration and size distribution of the microalgae Nannochloropsis gaditana were studied over the whole growth process. Various samples were taken during the light and dark periods the algae were exposed to. The distributions obtained exhibited positive skew, and no change in the type of distribution was observed during the growth process. The size distribution shifted to lower diameters in dark periods while in light periods the opposite occurred. The overall trend during the growth process was one where the size distribution shifted to larger cell diameters, with differences between initial and final distributions of individual cycles becoming smaller. A model based on the Logistic model for cell concentration as a function of time in the dark period that also takes into account cell respiration and growth processes during dark and light periods, respectively, was proposed and successfully applied. This model provides a picture that is closer to the real growth and evolution of cultures, and reveals a clear effect of light and dark periods on the different ways in which cell concentration and diameter evolve with time.The Authors wish to thank Repsol YPF for the financial support that provided (Project reference: Ingenio 2010-CDTI-Sost CO2-CEN-2008-1027) and the Generalitat Valenciana by the fellowship of one of the authors (Program VALI + D)

TGA/FTIR study of the decomposition of Heet tobacco in presence of zeolites and silicate compounds

This paper studied the thermal behaviour of Heet tobacco analysing the functional groups generated in the process of decomposition in inert and oxidative atmosphere. The effect of three zeolites, ZSM5, USY, and Beta, and two silicates, SBA-15 and Silica Fumed (SF) in the compounds of decomposition has been studied. The stages of decomposition of the tobacco (TGA) and the evolution of the functional groups with temperature (FTIR) have been analyzed. All additives produce significant changes in the volatiles generated under both atmospheres, being Beta zeolite and especially SBA-15 the materials more markedly reducing the yields of methylene, alcohols, CO, CO2 and carbonyl compounds, during the pyrolysis of Heet tobacco under nitrogen and air atmospheres. This effect may contribute efficiently to further reduce the toxicity of the Heet HNB tobacco.Financial support for this investigation has been provided by the “Conselleria de Educacion, Investigacion, Cultura y Deportes” (IDIFEDER 2018/009 and PROMETEO 2020/093)

The cell wall structure: developments in diagnosis and treatment of candidiasis

Candidiasis are among the fungal infections the most difficult to diagnose and treat. Research focused on specific fungal components which are absent in the host, such as the cell wall has lead to a better understanding of Candida albicans pathogenicity and clinical impact. The cell wall is responsible for antigenic expression and primary interaction with the host. It is composed mainly of β-glucans, chitin and mannoproteins, which account for the rigidity of the wall and for the fungal morphology. Of these components, mannoproteins might carry a “morphogenetic code” which might modulate the molecular architecture of the cell wall. The features of specific cell wall proteins as part of building blocks to form this structure is revised, and the usefulness of monoclonal antibodies obtained against cell wall components to study those processes, together with their clinical applicability, is discussed

Equilibrio entre fases en sistemas multicomponentes

Bases termodinámicas del equilibrio entre fases

Cálculo del equilibrio líquido-vapor. Diagramas de equilibrio

Diagramas y cálculo del equilibrio líquido vapor

Effect of the addition of zeolites and silicate compounds on the composition of the smoke generated in the decomposition of Heet tobacco under inert and oxidative atmospheres

Five potential additives, three zeolites and two silicates, have been studied for reducing the amount of compounds generated when smoking Heet tobacco. Pyrolysis-gas chromatography-mass spectrometry experiments (Py-GC/MS) show that this type of tobacco generates large amounts of nicotine and glycerol and compounds such as phenol, acetaldehyde, acetone and formaldehyde that are classified as harmful components and potentially harmful (HPHC). USY and SBA-15 are the additives that present major reductions in inert and oxidative atmosphere, being these reductions greater for SBA-15. These results have been confirmed by smoking experiments that show significant reductions for SBA-15, especially in the total particle matter (TPM) where a reduction of more than 40% is obtained for most of the compounds, being for several compounds even higher than 60%. These additives may further reduce the toxicity of Heet tobacco.Financial support for this investigation has been provided by the “Conselleria de Educacion, Investigacion, Cultura y Deportes” (IDIFEDER 2018/009 and PROMETEO2020/093)

Hydrothermal liquefaction (HTL) of animal by-products: Influence of operating conditions

Hydrothermal liquefaction (HTL) of Animal By-Products (ABP) is a promising technology for their recycling and disposal. Different operating parameters have been studied to determine their influence on the process. Higher heating values of biocrudes ranging between 35 and 39 MJ/kg have been obtained showing a maximum yield of 61% at 225 °C. At low HTL temperature, the products are similar to those of rendering process and the biocrude is mainly formed by triglycerides and fatty acids in a 90:10 ratio, approximately. By increasing temperature, the free fatty acid yield increases, as well as amides and heterocyclic compounds as a result of the triglycerides and protein reactions. Between 250 and 290 °C a great difference in the composition of the biocrude obtained is observed. Water content also showed significant effects on the product yields. Large amounts of foams were obtained at low water contents that were minimised when it is increased. This is a very important feature to be considered for scaling up the phase separation process. Glycerine amount in the aqueous phase was remarkable, as a consequence of fat hydrolysis. Increasing pH to 9 increases the extraction of organics into the aqueous phase, whereas operating at pH 5 yields similar amounts of biocrude as compared with neutral pH, with a higher percentage of fatty acids. Reusing of the aqueous phase is necessary for the viability of the process and leads to increasing amounts of dissolved organics in the aqueous phase with the number of cycles, reaching a saturation level after three-four recycling rounds.The research leading to these results has received funding from the European Community’s 7th Framework Programme (FP7-2007-2013) under Grant Agreement No. 603986

Study of the decomposition of Vacuum Gas Oils-Low Density Polyethylene blends: evolution of the liquids

Presentado como póster en el 11th Mediterranean Congress of Chemical Engineering, Barcelona 2008. Resumen publicado en el libro de actas del congreso.In this work, dynamic pyrolysis runs of different samples of vacuum gas oil (VGO), polyethylene (PE) and a vacuum gas oil-polyethylene blend with a 10% of PE (VGO-PE) have been performed in a vertical reactor in order to study the products obtained in the thermal and the catalytic pyrolysis using an equilibrium FCC catalyst. Different than the most works studying the composition of the products evolved in the pyrolysis process, which analyzes the overall gaseous or liquid product collected through the complete degradation of polymer, in this case, different samples along the process have been collected, and the evolution with the temperature (or the time) of the composition of the liquids evolved has been studied by GC/MS. The results obtained permit to better know the nature of the processes involved in each step of decomposition and to analyze the possibility of recycling plastics by mixing them with the vacuum gas oil in the refineries. The results obtained indicate that, in the thermal pyrolysis, the sample of VGO was not degraded, but a process similar to a fractionated distillation occurs, and the composition of the condensed product obtained at the exit of the reactor is very similar to that corresponding to the original VGO, where alkanes with more than 20 carbon atoms (CLO) were the main compounds of the liquids obtained. The composition of the liquids observed in the thermal pyrolysis of the VGO, PE blend seems to be a mixture of the corresponding to pure VGO and PE. However, the presence of the catalyst changes the selectivity, and for the three cases studied, the major compounds are in the range of the gasolines.Comisión de Investigación Científica y Tecnológica de la Secretaría de Estado de Educación, Universidades, Investigación y Desarrollo and the European Community (FEDER refunds) (CICYT PPQ2004-02187), Generalitat Valenciana (ACOMP06/162 and ACOMP/2007/094), and University of Alicante; Grupo de Procesado y Pirólisis de Polímeros (VIGROB099)