Francisco Lopez-Serrano

Francisco Lopez-Serrano
Universidad Nacional Autónoma de México | UNAM · Department of Chemical Engineering

Professor

About

54
Publications
47,277
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
400
Citations
Additional affiliations
February 2015 - January 2016
University of Guadalajara
Position
  • Profesor Huésped
January 2004 - December 2012
Universidad Nacional Autónoma de México

Publications

Publications (54)
Article
Full-text available
In this work, the dynamics of the bioconvection process of gravitactic microorganisms enclosed in a rectangular cavity, is analyzed. The dimensionless cell and energy conservation equations are coupled with the vorticity-stream function formulation. Then, the effects of the bioconvection Rayleigh number and the heating source on the dynamics of mic...
Article
Full-text available
In this work, polymerizations of styrene (St) in the presence of divinylbenzene (DVB) as a crosslinking agent and sodium 4-vinylbenzenesulfonate (VBS) have been performed in Pickering emulsions, using silica nanoparticles (SNps) as stabilizing agents and ammonium persulfate as a hydrophilic initiator. In oil-in-water Pickering emulsions with alkali...
Article
Full-text available
In this work, the Flory–Rehner equation is revisited to evidence the dependency of the interaction parameter on both polymer volume fraction and temperature. Such an analysis to estimate the true functionality of the interaction parameter is based on experimental data reported in the literature for the swelling behavior of NIPA hydrogels prepared a...
Article
The Pickering emulsion polymerization of Styrene (St), divinylbenzene (DVB) as a crosslinking agent and sodium 4-vinyl benzene sulfonate (VBS) used for in situ surface-modification of silica nanoparticles (SNps) was investigated. At 1.0 wt% DVB, amphiphilic SNps with hydrophobic patches were formed, further self-assembling into copolymer-SNps clust...
Article
A Pickering emulsion polymerization (PEP) was performed with styrene (Sty), silica and an initiator, both anionic, and small amounts (1.1 wt % total) of 4-vinyl pyridine (4VP), vinyl benzene sulfonate (VBS) and poly (ethylene glycol) methyl ether methacrylate (PEGMA) as co-aids. We focus on the analysis of the possible phenomena occurring during th...
Article
Full-text available
Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and pu...
Article
In this work, the Pickering emulsion polymerization of styrene (STY) with silica nanoparticles as stabilizers and ammonium persulfate (APS) as initiator, was studied. The effects of several co-aids, considered as modifying agents to vary the compatibility of colloidal silica (Ludox AM) between the polymer interface during the emulsion polymerizatio...
Article
A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately des...
Article
The bioconvection of gravitactic microorganisms, through linear analysis and numerical simulation is presented. Using the basic state as initial condition for both microorganisms and streamlines, the critical Rayleigh number and the bioconvection are predicted. The dynamic microorganisms’ behavior is influenced by the initial spatial distribution....
Article
The trajectories of chaotic fluctuations in dilute micellar solutions that typically occur during the creation and destruction of shear‐induced structures (SIS) in flow inception of a 0.4 wt.% cetyltrimethylammonium tosilate (CTAT) aqueous solution and an aqueous solution of 3 mM cetyyltrimethylammonium bromide‐ sodium salicylate (CTAB‐NaSal), are...
Article
In this work, a simple comprehensive mathematical model, to understand the main mechanisms occurring in the semicontinuous heterophase inverse polymerization of acrylamide, is reported. A Mayo-Lewis extended model, including nucleation and coagulation, is assessed with experimental conversion, particle density and inferred average number of radical...
Article
Full-text available
A different internal reference band in Raman spectroscopy, to monitor SiO2-supported styrene Pickering emulsion polymerizations, is postulated. Raman spectroscopy allowed detecting silanol/styrene-aromatic-ring interactions yielding a deviation, against conversion, in the 1630/1000 wave number ratio, commonly used for monitoring styrene polymerizat...
Article
Full-text available
In this work, the micro-macro approach is used to simulate the flow of dilute polymer solutions by means of a kinetic model coupled with the dynamics of a transient network. The transient network modeling is based on the original formulation, in which the kinetics of microstates describes the complexity of interactions among the macromolecules susp...
Article
A step towards the understanding of some mechanistic events occurring in the styrene Pickering emulsions, using a SiO2 dispersion, is presented. Polymerizations at 80°C with different levels of a water soluble initiator were performed. The emulsion polymer content was ca. 15% with conversions close to 90%. With conversion and particle size measurem...
Conference Paper
Full-text available
The microemulsion polymerization of 1,3-butadiene (Bd) at 60 °C using dodecyltrimethyammonium bromide (DTAB) and dodecyldimethyammonium bromide (DDAB), is assessed in this work. The conversion, its time-derivative as well as the monomer concentration inside the particles show anomalous behaviors compared with conventional emulsion or microemulsion...
Book
Full-text available
PRÓLOGO La Universidad enfrenta un reto singular. En la actualidad su papel como proveedor de contenido ya no puede considerarse suficiente, simplemente porque el internet ofrece muchas fuentes en constante actualización, situación que lamentablemente no garantiza que la información ahí contenida sea veraz ni de calidad. En ese sentido, las institu...
Article
A generalized model is presented here for the semicontinuous heterophase polymerization of methyl and hexyl methacrylate, which have very different water solubility. In this polymerization technique, neat monomer is fed at a controlled rate over a monomer-free aqueous solution of surfactant and initiator, to produce nanometer size particles with co...
Article
Full-text available
The present paper deals with the poly(lactic acid) (PLA) reactive processing simulation in a uniform corotating twin-screw extruder that can be readily turned into practical applications in pilot and industrial equipment. The simulator provides a cause-effect guide that can be useful for starting an experimental setup in a reactive screw extruder f...
Article
A previously presented model with four states (conversion, active and inactive particles and micelles) is further tested with conversion versus time experimental data at 50, 60, and 70°C, to recognize the main events occurring in styrene microemulsion polymerization. The S-shaped conversion–with no overprediction- and the bell-shaped active particl...
Article
A methodology is presented to obtain a kinetic model for curing reactions, from conversion against time and the glass-transition temperature versus conversion data. Isothermal runs for a cyanate ester resin from 140 to 190°C, reported previously, were evaluated. The approach utilizes the conversion measurement time derivatives that allow following...
Article
The semi-continuous heterophase polymerization (SHP) under monomer-starved conditions of methyl methacrylate and hexyl methacrylate is reported, at various monomer addition rates to elucidate the effect of monomer solubility on the mechanism of particle nucleation and growth. Polymer particles in the nanometer range from both monomers were obtained...
Chapter
A simple model for the batch emulsion polymerization of styrene, considering different size reactors has been studied. The resulting differential equation-set was solved for the temperature (jacket and reactor) and conversion profiles as a function of time. The fundamental dimensionless numbers, appearing in the different terms of the reaction equa...
Conference Paper
Full-text available
Compared with the standard regression method alone, the proposed approach incorporates additional information contained in the derivative of the smoothed conversion measurement that does not require measuring the average number of radicals per particle. Moreover, an uncoupling technique is applied to facilitate parameter estimation. On the basis of...
Article
A simple four-state model containing five-parameters, in conjunction with experimental conversion, particle number density and average molar masses, is presented to reproduce the semicontinuous heterophase polymerization of butyl methacrylate. The model adequately describes the experimental evolutions of conversion, particle size, average number of...
Conference Paper
Full-text available
A methodology is presented to obtain a kinetic model for curing reactions from conversion against time and the glass transition temperature versus conversion data. Isothermal runs for a cyanate ester resin from 140 to 190°C, reported previously, were evaluated. The approach utilizes the conversion measurement time-derivatives which allow following...
Chapter
Full-text available
Microemulsion and semicontinuous heterophase polymerizations are processes that allow the synthesis of nanosized polymer particles (10–100 nm) with narrow size distributions in a simple and routinely fashion. Methods to overcome the main drawback of microemulsion polymerization, mainly low polymer/surfactant weight ratio, are reviewed. Relevant lit...
Article
Full-text available
A simple model for cure kinetics, based on the Churchill-Usagi correlation, is presented here. This proposal, intended for engineering purposes, is capable of reducing computational time to facilitate, even with analytic solutions, the kinetics description, especially when more complex systems are being studied. In spite of the model’s simplicity,...
Article
Full-text available
A simple model for cure kinetics, based on the Churchill-Usagi correlation, is presented here. This proposal, intended for engineering purposes, is capable of reducing computational time to facilitate, even with analytic solutions, the kinetics description, especially when more complex systems are being studied. In spite of the model's simplicity,...
Conference Paper
Full-text available
En el presente trabajo se presenta el monitoreo, mediante espectroscopía Raman, de la conversión de la reacción de polimerización de la acrilamida en solución acuosa vía radicales libres, tanto en condiciones isotérmicas como cuasiadiabáticas. La evolución de la reacción se realiza siguiendo el decremento de la intensidad del pico en 1287 cm-1, per...
Conference Paper
Full-text available
The semicontinuous heterogeneous polymerization (SHP) is examined with a four-state (conversion, total particle number,average radical number per particle and reactor volume) and a five-parameter (rates of entrance of radicals to micelles and to particles, exit of radicals from particles, homogeneous nucleation and coagulation) model, along with ex...
Article
The synthesis of styrene-acrylonitrile copolymers by semicontinuous heterophase polymerization is reported here. The effect of feed composition at a fixed addition rate of monomer mixture on kinetics, particle size, polymer content, and molar masses, was studied. This process permits the synthesis of nanolatexes containing narrow size-distribution...
Conference Paper
Full-text available
A dynamical model for the emulsion polymerization of styrene within a batch reactor has been studied. This model includes the main steps for styrene polymerization, along with the relevant balance equations. The resulting set of differential equations was solved for temperature profile and monomer consume as a function of time. Emphasis is put on t...
Article
One-phase microemulsion regions at 25 and 60°C and the polymerization at 60°C in o/w microemulsion formed by 1,3-butadiene, water, and a mixture of the surfactants, dodecyltrimethylammonium bromide, and didodecyldimethylamonium bromide (3/1 w/w), are reported. The polybutadienes obtained here have similar characteristics to those of their homologou...
Article
On the basis of the data processing technique associated with the integro-differential (ID) modeling assessment methodology, the styrene-acrylonitrile microemulsion copolymerization system is studied, with a three-state (conversion, active particles and micelles) and four-parameter model (entrance and exit of radicals to and from particles, monomer...
Article
The problem of determining the constancy of the diffusion coefficient, or its dependency on moisture content, from observations of moisture content during the course of the drying is addressed. The method employed departed from the usual finite dimensional model representation of the drying process, a truncated Fourier series solution to the diffus...
Article
In this work, the microemulsion polymerization modeling problem is addressed with an integrodifferential approach. The procedure was applied to experimental data, previously presented, on the microemulsion polymerization of hexyl methacrylate (C6MA) and styrene (STY). It was found that: (i) the nucleation rate is not linear with time, as assumed be...
Article
In this work, the problem of understanding some underlying phenomena in microemulsion polymerization is addressed, with an integrodifferential (ID) approach combining notions and concepts from microemulsion kinetics and thermodynamics. The procedure is applied to previously reported experimental data on the polymerization of hexyl methacrylate (C6M...
Article
Full-text available
A model based on kinetic, thermodynamic and physicochemical concepts, is presented and an integrodifferential approach to find the fundamental events, is used for microemulsion polymerization (MEP). The procedure was applied to experimental conversion data of hexyl methacrylate (C6MA) and styrene (STY) in MEP. It was found that: (i) nucleation rate...
Article
A model based on kinetic, thermodynamic and physicochemical concepts, is presented and an integrodifferential approach to find the fundamental events, is used for microemulsion polymerization (MEP). The procedure was applied to experimental conversion data of hexyl methacrylate (C6MA) and styrene (STY) in MEP. It was found that: (i) nucleation rate...
Conference Paper
Full-text available
This is a continuation of a work presented recently (López-Serrano et al., 2010) and the purpose is to continue analyzing conversion-against-time data (Zhao and Hu, 2007), of NCOCH2(CF2)6CH2OCN(2,2,3,3,4,4, 5,5,6,6,7,7 dodecafluorooctanediol dicyanate ester) at temperatures from 140 to 190°C, in order to search for an apparent reaction mechanism to...
Article
The model assessment and discrimination problems for copolymerization systems with measurements of polymer composition and average propagation rate constant versus feed composition are addressed via an integrodifferential stochastic estimation approach with error propagation analysis. The methodology is applied to perform the ultimate versus penult...
Article
The effects of particle size and polymer location (core or shell) on the mechanical properties of core/shell materials composed of polystyrene (PST) and poly(butyl acrylate) (PBA) made by a two-stage emulsion or microemulsion polymerization process are reported. Low-seed content (LSC) latexes were made by batch polymerization in microemulsions stab...
Article
An integrodifferential estimation approach is applied to draw the reactivity ratio (RR) dependencies on the monomer feed composition. The approach combines the integral method robustness with the differential method discrimination capability and includes an uncertainty assessment in terms of the number, location, and quality of experimental data. T...
Article
In this work the problem of determining the dependencies on conversion of the initiation rate (Ri), the propagation (kp), termination (kt), and transfer to monomer (ktr) kinetic constants in the thermally initiated free-radical polymerization of styrene is addressed. A nonlinear observability analysis establishes that the parameter groupings Ri, κ...
Article
The polymerization of styrene in o/w microemulsions stabilized with dodecyltrimethylammonium bromide (DTAB) with or without cosurfactant (n-butanol, n-hexanol or n-octanol) is examined here. The addition of a cosurfactant enhances the one-phase region in the order: n-butanol > n-hexanol > n-octanol. The kinetics of polymerization slows down in the...
Patent
Full-text available
A process is provided for making a carbon-filled rubber having a uniform dispersion of nanometric-sized carbon black particles. Fluffy carbon black is received as a slurry in water and added to latex rubber before or during coagulation ina an emulsion styrene buatadiene plant, or fluffy carbon black is similarly incorporated in rubber using a diffe...
Article
A recently developed model for o/w microemulsion polymerization, tested only with styrene, is validated here by comparing its predictions with experimental data from the polymerization of three monomers with different chemical structures and water solubilities. The model reproduces well the kinetic data as well as the characteristics of the latex a...
Article
Moedling of emulsion polymerization is a controversial subject because different models, based on contradictory assumptions, can describe the same set of experimental data, In order for the theoretical and experimental studies on emulsion polymerization to yield meaningful conclusions, the issue of parameter estimation with modeling consistency sho...
Patent
Full-text available
A process has been developes to substancially reduce the residual monomer resultin at the end of the emulsion polymerization reaction. The process consists in submitting the latex to a redox process after the polymerization reaction. The recommended environmet consists of vinyl monomerd and/or conjugated dienes homo or copolymer that has a residual...
Article
Microemulsion and emulsion polymerization have many similarities but also important differences in reaction kinetics. The large amount of surfactant required in microemulsion polymerization causes a peculiar kinetic behavior (i.e. only two reaction rate periods, continuous generation of particles through the entire reaction and the production of na...
Article
The development of heterogeneous structure during the polymerization of a polyurethane system using a polyether diol of M̄n = 2000 as the soft segment and 4,4′-diphenylmethane disocyanate extended with 1,4-butanediol as the hard segment was monitored following the amount of light transmitted by the sample and the increase in viscosity of the reacti...
Article
A new method is presented for calculating average values of molecular weight, chain length and sequence distributions in linear copolymerization. The method provides a considerable expedient to these results over most other approaches since the average values are calculated directly, bypassing the calculation of distributions themselves. The approa...
Article
Typescript (photocopy). Thesis (M.S.)--University of Minnesota, 1979. Includes bibliographical references (leaves 125-129).

Network

Cited By

Projects

Project (1)
Project
The overall objective of this research project is to further pursue the understanding of heterophase polymerization systems, dispersed by solid particles (Pickering emulsions). Conducting experiments and measurements in the participants’ laboratories, and corroborating the mathematical models proposed by us, by estimating parameters, representing mechanistic events in the process (such as entrance and exit of radicals from particles, monomer partition at various stages, homogeneous and coagulative nucleation, radicals’ generation in the aqueous phase, etc.) These events appear in mathematical models, and always will be validated with experimental measurements. It should be mentioned that up to date, in the searched literature, a full mathematical model has not been presented to describe Pickering emusliones polymerization.