Fabricio Machado

Uma Revisão Sobre os Processos de Polimerização em Suspensão

Several processes can be employed for manufacturing polymer materials. Each process presents some intrinsic features that lead to production of resins with peculiar properties, which define the end-use application of the final polymeric material. Suspension polymerization processes are extensively used because of their many advantages, such as the easy separation of the polymer particles, easy removal of the heat of reaction, easy temperature control and low levels of impurities and additives in the final polymer material. For this reason, suspension polymerization processes are suitable to produce polymer resins for biotechnological and medical applications. The main objective of this work is to discuss the fundamental aspects of suspension polymerization processes, focusing upon the effects of the main process variables on the performance of suspension polymerizations. Additionally, it is shown that near infrared spectroscopy (NIRS) can be useful for monitoring and real time control of suspension processes, allowing for production of polymer beads with controlled morphology.

A Survey on Synthesis Processes of Structured Materials for Biomedical Applications: Iron-based Magnetic Nanoparticles, Polymeric Materials and Polymerization Processes.

Magnetic materials based on iron oxides are extensively designed for several biomedical applications. Heterogeneous polymerization processes are powerful tools for the production of tailored micro-sized and nanosized magneto-polymeric particles. Although several polymerization processes have been adopted along the years, suspension, emulsion and miniemulsion systems deserve special attention due to its ability to produce spherical polymer particles containing magnetic nanoparticles homogeneously dispersed into the polymer thermoplastic matrices. The main objective of this paper is to review the main methods of synthesis of iron-based magnetic nanoparticles and to illustrate how typical polymerization processes in different dispersion medium can be successfully used to produce engineered magnetic core-shell structures. It is exemplified the use of suspension, emulsion and miniemulsion polymerization processes in order to support experimental methodologies required for the production of magnetic polymer particles intended for biomedical applications such as intravascular embolization treatments, drug delivery systems and hyperthermia treatment.

Reciclagem de poli(estireno-divinilbenzeno) via processo de polimerização em massa-suspensão

This work illustrates the reuse of ion exchange resins based on crosslinked styrene-divinyl benzene copolymer (Sty-DVB) for the production of polymeric materials. Micro-sized particles of polystyrene and poly(styrene-ethyl acrylate) were obtained by mass-suspension sequential polymerization process. With the proposed experimental technique it was possible to perform proper dispersion of the Sty-DVB in the thermoplastic matrix of polystyrene. The final material showed good thermal stability, and a degradation profile similar to that for pure polystyrene. It was also observed that polymer particles with spherical morphology can be obtained. In addition, the incorporation of ethyl acrylate into the polystyrene chains minimizes the undesirable effect of fracture in polymeric particles, improving the mechanical properties of the final material.

Monitoring of Vinyl Chloride Suspension Polymerization Using NIRS. 2. Proposition of a Scheme to Control Morphological Properties of PVC

Abstract This article introduces the use of in-line and in situ monitoring of the dynamic evolution of PVC morphological properties in suspension polymerization reactions based on near infrared spectroscopy (NIRS) intended for control applications. It is shown for the first time that it is possible to follow the dynamic evolution of morphological properties (such as the bulk density, BD, and the cold plasticizer absorption, CPA) in real time. The obtained results indicate that closed-loop control schemes can be properly implemented to control end-use resin properties, which depend upon the morphology of PVC polymer particles. Suspension polymerization of vinyl chloride performed in bench and pilot scale showed that process variables, such as the agitation speed and the amount of suspending agents) can be successfully manipulated in order to control the morphological parameters of PVC resin. Based on this information, a control scheme for these parameters is proposed.

Monitoring of Vinyl Chloride Suspension Polymerization Using NIRS. 1. Prediction of Morphological Properties

Abstract The monitoring of polymer properties is frequently performed through sampling and off-line measurement of quality parameters in lab scale. Because of the long time required to perform off-line analyses, off-line data are generally inadequate for control purposes. As impurities cannot be detected in-line and can exert significant influence on the polymerization kinetics, modifications of some important quality parameters (such as the morphological characteristics of PVC particles) can only be detected at the end of the polymerization, causing major production losses. In the present work it is shown for the first time that it is possible to monitor some of the morphological properties of PVC (such as the bulk density, BD, the cold plasticizer absorption, CPA, and the average particle diameter Dp) in situ and in real time with the help of near infrared spectroscopy (NIRS) in suspension polymerization processes.

Synthesis of polymer/inorganic hybrids through heterophase polymerizations

Abstract Heterophase polymerization processes such as suspension, emulsion and miniemulsion play a fundamental role on the synthesis of polymer/inorganic hybrids. Depending on the reaction system, hybrid micro- and nanoparticles are produced, exhibiting successful incorporation of inorganic fillers into the polymer particles, due to the proper encapsulation and / or dispersion into the growing polymer chains during the polymerization. Polymer/magnetic nanoparticles and polymer/clays-based nanocomposites are representative examples of hybrid materials synthesized through heterophase polymerization processes intended for several end-use application purposes, as for instance, medical devices, drug delivery systems, adhesives, paints and coatings, paper, textiles, embolization agents, sensors, enzyme support, among others.

Oleaginous Biomass for Biofuels, Biomaterials, and Chemicals

Concerns about negative environmental impacts and questions of future availability surrounding the long-term use of fossil sources as a basis for production of fuels, and a plethora of derivatives, are matters of increasing importance. Consequently, plant biomass sources capable of efficiently replacing fossil fuel resources are gaining relevance as biofuels and in the oleochemical industry. The array of chemical compositions of vegetable oils and fats, the possibility of producing biomass in a sustainable way, and the development of routes for their transformation are the main drivers of this growing demand. This chapter covers topics of global production and consumption of the principal vegetable oil commodities, the comparative chemical composition of oils and fats, the potential use of the biological storage structures of oils and fats, the main processes of transforming oils into biofuels, and the production of bio-based polymers. Also, mechanisms of the functionalization of vegetable oils are stressed.

Preparation and Characterization of Tubular Composite Membranes and their Application in Water Flow Measurements

The latest technologies require materials with combination of properties that are not usually found in conventional materials. Organic-inorganic hybrid materials emerge as alternatives to the synthesis of low cost new functional materials. The constituent polymer-clay nanocomposites are intended effectively for the treatment of oily effluents. The removal of oily effluents was evaluated using composite membranes with different nanocomposite percentages, consisting of a mineral clay BrasgelTM smaller than 2 μm and ultra high molecular weight polyethylene. The sample of clay was characterized by X-Ray Diffraction (XRD) and Cation Exchange Capacity (CEC), while the membranes by scanning electron microscope (SEM). The produced composite membranes efficiencies were evaluated by continuous flow for 1 hour. The results clearly confirmed that membranes incorporated with a higher percentage of nanocomposites achieved greater stability and less time as assessed in water flow.

Implantable medical devices and tissue engineering: An overview of manufacturing processes and the use of polymeric matrices for manufacturing and coating their surfaces

Medical devices are important diagnosis and therapy tools for several diseases which include a wide range of products. Technological advances in this area have been proposed to reduce adverse complication incidences. New technologies and manufacturing processes, as well as development of new materials or medical devices with modified surface and the use of biodegradable polymeric devices such as substrate for cell culture in the field of tissue engineering have attracted considerable attention in recent years by the scientific community intended to produce medical devices with superior properties and morphology. This review article focused on implantable devices, addresses the major advances in the biomedical field related to the devices manufacture processes such as 3D printing and hot melting extrusion, and the use of polymer matrices composed of copolymers, blends, nanocomposites or grafted with antiproliferative drugs for manufacturing and/or coating the devices surface.

Modelling and Parameter Estimation of Enzymatic Biodiesel Synthesis

Abstract The current work addresses the modelling and parameter estimation of the biodiesel synthesis using supported lipases as catalysts. A kinetic reaction model was proposed in order to describe the enzymatic (trans)esterification reaction of vegetable oils and the set of kinetic parameters were numerically estimated with help of the direct search Complex algorithms. The proposed model was evaluated for different experimental conditions, leading to a very suitable prediction of the process data. In summary, the general proposed model is able to predict very well the reaction behavior of biodiesel (BD). Based on the algebraic-differential model performance, the proposed strategy can be successfully used to describe and optimize the biodiesel production through enzymatic reactions performed in batch and semibatch operating mode.