An updated review on suspension polymerization is presented. The time period from 1991 to 1995 stressed, as well research articles or reports not considered in previous reviews. Our aimed at providing a sound basis for the theoretical background required build an effective model particle size distribution (PSD) polymerization. All major phenomena that affect PSD are considered, and proposed approach develop accurate, yet simple, included. Most of experimental information this related...

Abstract A user‐friendly program has been developed to estimate copolymerization reactivity ratios based on a nonlinear minimization algorithm. The use of an optimal experimental design for when the Mayo–Lewis model applies is presented. applicability demonstrated using actual and simulated data.

Polymer flooding is a promising enhanced oil recovery (EOR) technique; sweeping reservoir with dilute polymer solution can significantly improve the overall recovery. In this overview, polymeric materials for are described in general terms, specific emphasis on desirable characteristics application. Application-specific properties should be considered when selecting or developing polymers and carefully evaluated. Characterization techniques informed by current best practices; several herein....

Abstract A practical methodology for the computer modelling of multicomponent free radical polymerizations solution and emulsion systems has been developed. The approach is general providing a common model framework which applicable to many comononer systems. Model calculations include conversion monomers, multivariable distributions concentrations monomers bound in polymer chains molecular weights, long short chain branching frequencies, microstructure crosslinked gel content when...

The enhanced features of a computer program (RREVM) for the estimation copolymerization reactivity ratios using statistically sound techniques are illustrated with experimental and simulated case studies. In parallel, literature review is given on ratios. Both aspects extensions based articles by Dube et al.1 Rossignoli Duever.2 © 1998 John Wiley & Sons, Inc. J Polym Sci A: Chem 36: 813–822,

Abstract The main goals in operating a polymer reactor are high yield (productivity), product quality, and safe operation (of course, within some overall economic framework). These very difficult, if not impossible, to achieve without efficient reliable online measurement [characterization, monitoring, sensing) techniques. Although considerable advances have been made the last twenty years many aspects of reaction engineering production technology, sensor technology has remained rather...

Geckos, which are capable of walking on walls and hanging from ceilings with the help micro-/nano-scale hierarchical fibrils (setae) their toe pads, have become main prototype in design fabrication fibrillar dry adhesives. As unique feature pads geckos allows them to develop an intimate contact substrate animal is or clinging to, it expected that setae exchange significant numbers electric charges contacted via electrification (CE) phenomenon. Even so, possibility occurrence CE contribution...

Chitosan films containing citric acid were prepared using a multi-step process called heterogeneous crosslinking. These neutralized first, followed by addition, and then heat treated at 150 °C/0.5 h in order to potentially induce covalent The viscoelastic storage modulus, E′, tanδ studied dynamic mechanical analysis, compared with neat elucidate possible crosslinking acid. Films also various concentrations of model crosslinker, glutaraldehyde, both homogeneously heterogeneously. Based on...

Abstract Several models have been proposed in the literature over last two decades order to simulate free-radical homopolymerizations. However, most of these deal with one specific monomer system, usually under restricted polymerization conditions.

Abstract The available on‐line and in‐line sensor technologies developed for polymerization reactors from 1990 until today are discussed critically reviewed. About 600 references included, which evidence the growth in technology last two decades. Sensors operational parameters polymer (i.e. temperature, pressure, level flow) as well sensors property monitoring calorimetry, chromatography spectroscopy, among others) included. Complementary topics such state estimation, multivariate...

Abstract The goal is to present an alternative technique for reactivity ratio estimation in copolymerization. Typically, ratios are estimated using the instantaneous copolymer composition equation, based on low conversion data. However, experimental data from full copolymerization trajectory would, principle, be more advantageous, and shy away commonly used restrictive assumptions. Estimation cumulative models eliminates difficulties associated with stopping reactions at conversion, while...

ABSTRACT The ionic strength (IS) of polyelectrolyte solutions plays an important role in influencing reaction kinetics. largely unstudied effect IS on monomer reactivity ratios and copolymerization rates acrylamide (AAm) acrylic acid (AAc), the form sodium acrylate (NaAc), is investigated. Salt addition affects nature overall charges solution diminishes electrostatic repulsions between reacting chains. Therefore, changing by incorporating salts affect not only point estimates but also...

A novel electrostatic MEMS gas sensor is demonstrated. It employs a dynamic-bifurcation detection technique. The detects ethanol vapor in binary mode, reporting ON-state (1) for concentrations above preset threshold and OFF-state (0) below the threshold. sensing mechanism exploits qualitative difference between state before after dynamic pull-in bifurcation.Experimental demonstration was carried out using laser Doppler vibrometer to measure response detection. able detect as 100 ppb dry...

Investigations of the effects polymerization conditions on molecular weight distribution (MWD) polyethylene synthesized with soluble metallocene/methylaluminoxane (MAO) catalysts have been performed. The following variables were investigated in this study: catalyst type, temperature, concentration, MAO chain transfer agent, ethylene partial pressure, as well substitution trimethylaluminium (TMA), and different activities polyethylene. Similarities differences other published results are...

Abstract Polymer reactor control problems often lack frequent measurements of polymer properties, while other environment measurements, such as temperatures, are readily available. The experimental application a new estimator for handling multirate measurement systems is presented. estimator, in conjunction with detailed nonlinear model and all at their respective sampling rates, able to provide predictions the process variables related quality (weight‐average molecular weight) quantity...

Abstract A series of poly(ethylene‐ co ‐1‐hexene) samples made with rac ‐ethylene bis(indenyl)zirconium dichloride/methylaluminoxane were analyzed by crystallization analysis fractionation (CRYSTAF). The nine had comonomer contents 0–4.2 mol % 1‐hexene a narrow range molecular weights (34,000–39,000 g/mol). Because all the copolymer narrow, unimodal chemical composition distributions, they ideal as calibration standards for CRYSTAF. linear curve was constructed relating peak temperature from...

A critical look at the possibility of controlling molecular weight distribution (MWD) polyolefins by combining metallocene/methylalumoxane (MAO) catalysts is offered. Catalysts investigated were bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2), its titanium and hafnium analogues (Cp2TiCl2 Cp2HfCl2), as well rac-ethylenebis(indenyl)zirconium (Et(Ind)2ZrCl2). As observed other researchers, MWD polyethylene can be manipulated soluble catalysts, which on their own produce polymer with narrow...