Comparison of thermal properties of ethylene‐norbornene copolymers prepared by batch and semi‐batch processes

Ethylene‐norbornene copolymers (ENCs) with various norbornene (NB) fractions could be synthesized by metallocene catalyst in both batch and semi‐batch processes. The batch process with long reaction time produced the ENC samples having considerable copolymer composition drift (CCD) while the semi‐batch process yielded narrow CCD. Furthermore, the effects of CCD on the resultant ENC's thermal properties were discussed. It was found that the thermal properties were dependent on both the NB fraction in obtained ENC and its CCD. The work demonstrated the importance of controlling CCD in the production of ENCs for superior materials properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Safe‐steering of batch process systems

This work considers the problem of controlling batch processes to achieve a desired final product quality subject to input constraints and faults in the control actuators. Specifically, faults are considered that cannot be handled via robust control approaches, and preclude the ability to reach the desired end‐point, necessitating fault‐rectification. A safe‐steering framework is developed to address the problem of determining how to utilize the functioning inputs during fault rectification to ensure that after fault‐rectification, the desired product properties can be reached upon batch termination. To this end, first a novel reverse‐time reachability region (we define the reverse time reachability region as the set of states from where the desired end point can be reached by batch termination) based MPC is formulated that reduces online computations, as well as provides a useful tool for handling faults. Next, a safe‐steering framework is developed that utilizes the reverse‐time reachability region based MPC in steering the state trajectory during fault rectification to enable (upon fault recovery) the achieving of the desired end point properties by batch termination. The proposed controller and safe‐steering framework are illustrated using a fed‐batch process example. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Multivariate statistical process monitoring of batch‐to‐batch startups

In batch processes, multivariate statistical process monitoring (MSPM) plays an important role for ensuring process safety. However, despite many methods proposed, few of them can be applied to batch‐to‐batch startups. The reason is that, during the startup stage, process data are usually nonstationary and nonidentically distributed from batch to batch. In this article, the trajectory signal of each process variable is decomposed into a series of components corresponding to different frequencies, by adopting a nonparametric signal decomposition technique named ensemble empirical mode decomposition. Then, through instantaneous frequency calculation, these components can be divided into two groups. The first group reflects the long‐term trend between batches, which extracts the batch‐wise nonstationary drift information. The second group corresponds to the short‐term intrabatch variations. The variable trajectory signals reconstructed from the latter fulfills the requirements of conventional MSPM. The feasibility of the proposed method is illustrated using an injection molding process. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3719–3727, 2015     

Lipolytic enzyme production in batch and fed‐batch cultures of Ophiostoma piceae and Fusarium oxysporum

Lipase and esterase production by Ophiostoma piceae and Fusarium oxysporum were enhanced and extended by developing a fed‐batch process in stirred tank reactors. Fed‐batch strategy improved lipolytic enzyme production from Ophiostoma piceae in both 2 and 20 dm³ stirred tank reactors. However, fed‐batch fermentation of Fusarium oxysporum in the 2 dm³ reactor was more effective than both batch and fed‐batch fermentations in the 20 dm³ reactor. When a medium composed of only carbon and nitrogen source was intermittently fed to the cultures, the maximum specific lipase activity was improved by more than 80% and 35% in Ophiostoma piceae and Fusarium oxysporum cultures respectively. The maximum specific esterase activity was improved by 20% and 15% in Ophiostoma piceae and Fusarium oxysporum cultures respectively. The duration of production for both fungi extended from 144 to 216 h compared with a batch culture under the same condition. © 2000 Society of Chemical Industry     

Nanocrystalline Fe‐Ni alloy/polyamide 6 composites of high mechanical performance made by ultrasound‐assisted master batch technique

The focus of this study is to improve the dispersion state of nanocrystalline (nc) Fe‐Ni particles in polyamide 6 (PA6) matrix and the filler‐matrix interfacial interactions to provide Fe‐Ni alloy/PA6 nanocomposites of remarkable mechanical performance for engineering applications. nc Fe₄₀Ni₆₀ particles were chemically synthesized. Then Fe₄₀Ni₆₀/PA6 nanocomposites of various nanofiller loading were prepared by compounding via a newly modified master batch technique called ultrasound assisted master batch (UMB), followed by injection molding (IM). Their mechanical properties, morphology and structural parameters were characterized and compared with the corresponding properties of Fe₄₀Ni₆₀/PA6 nanocomposites made by solution mixing (SM) and IM. The study reveals that the UMB process is more cost effective and time efficient, simpler and easier to scale up compared with the SM process. In addition, UMB nanocomposites exhibit superior mechanical properties and distinctive morphology compared with the corresponding SM ones. Moreover, structural analyses indicate that physical structural changes occurred in PA6 due to presence of alloy particles are affected differently by the different compounding methods, profound understanding of such phenomenon is focused throughout the article. These distinctive advantages recommend that UMB technique can be of great potential in commercial production of polymer nanocomposites (PNCs). It is concluded that the sonication of nc Fe₄₀Ni₆₀ particles in dilute polymer solution during UMB compounding, a new step that is incorporated for the first time in the master batch process, is mainly responsible for the good wetting between nanoparticles and polymer chains, strong filler‐matrix interactions and consequently the remarkable mechanical performance of UMB PNCs. POLYM. COMPOS., 35:2343–2352, 2014. © 2014 Society of Plastics Engineers     

Improvement of a fed‐batch process for high level xylanase production by a Bacillus strain

In this paper, the improvement of a fed‐batch fermentation from the point of view of an industrial xylanase production process is described. The Bacillus strain chosen for this study is able to produce high quantities of a xylanase that is suitable to be used as bleach boost agent in chlorine‐free bleaching sequences of paper pulp. It was found that xylo‐oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1 g dm^?3 xylose equivalents led to catabolite repression. A substrate‐limited fed‐batch process, that is the most adapted, was furthermore improved with regard to nutrient requirement of the microorganism, especially the nitrogen source. A process with constant supply of a culture medium containing xylan, peptone and mineral nitrogen was able to produce 20 240 nkat cm^?3 with a productivity of 910 nkat cm^?3 h^?1, which places the process among the best ever reported. © 2001 Society of Chemical Industry     

Molecular weight and the Mark‐Houwink relation for ultra‐high molecular weight charged polyacrylamide determined using automatic batch mode multi‐angle light scattering

This study presents an automatic batch mode (i.e., off‐line) multi‐angle light scattering (MALS) method for the molecular weight (MW) determination of ultra‐high MW (UHMW) polyacrylamide (PAM) homopolymer and acrylamide copolymers. This method combines a MALS detector with a sample dilution and injection device that automatically delivers a concentration gradient from a stock solution. The automation makes it practical to use the batch MALS method for routine MW analysis of UHMW polymers. The automatic batch MALS analyses of a series of poly(sodium acrylate‐co‐acrylamide) (30:70 mol %) in 1.0M NaCl show a non‐linear Mark‐Houwink relation in the MW range of 1.2 × 10⁶ to 12.6 × 10⁶ g mol^?1. The entire molecular weight range can be fit with a quadratic relation or two linear equations, one for molecular weight up to 5.3 × 10⁶ g mol^?1 and the other from 5.3 × 10⁶ to 12.6 × 10⁶ g mol^?1. The non‐linear Mark‐Houwink relation suggests that the extrapolation of the Mark‐Houwink equation beyond the measured MW range into the UHMW regions can significantly overestimate the MW of the UHMW polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43748.     

Effect of sucrose on nisin production in batch and fed‐batch culture by Lactococcus lactis

The effects of sucrose on cell growth and nisin production by Lactococcus lactis were investigated in batch and pH feed‐back controlled fed‐batch cultures. In batch cultures, nisin titer reached its maximum, 2658 IU cm^?3, at the initial sucrose concentration of 30 g dm^?3. With sucrose concentrations higher than 30 g dm^?3, nisin production decreased while the biomass was not influenced significantly. By using the pH feed‐back controlled method, residual sucrose concentration could be controlled well in fed‐batch cultures and three conditions (sucrose maintained at 2, 16, 20 g dm^?3, respectively) were evaluated. Maintaining a low sucrose concentration at 2 g dm^?3 during feeding favored nisin biosynthesis, and the maximum nisin titer obtained was 4961 IU cm^?3 compared with 3370 IU cm^?3 (16 g sucrose dm^?3)and 3498 IU cm^?3 (20 g sucrose dm^?3), respectively. Copyright © 2005 Society of Chemical Industry     

Robust batch‐to‐batch optimization in the presence of model‐plant mismatch and input uncertainty

In model‐based optimization in the presence of model‐plant mismatch, the set of model parameter estimates which satisfy an identification objective may not result in an accurate prediction of the gradients of the cost‐function and constraints. To ensure convergence to the optimum, the predicted gradients can be forced to match the measured gradients by adapting the model parameters. Since updating all available parameters is impractical due to estimability problems and overfitting, there is a motivation for adapting a subset of parameters for updating the predicted outputs and gradients. This article presents an approach to select a subset of parameters based on the sensitivities of the model outputs and of the cost function and constraint gradients. Furthermore, robustness to uncertainties in initial batch conditions is introduced using a robust formulation based on polynomial chaos expansions. The improvements in convergence to the process optimum and robustness are illustrated using a fed‐batch bioprocess. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2660–2670, 2017     

Sub‐stage PCA modelling and monitoring method for uneven‐length batch processes

For the characteristic of multistage of batch processes, a new PCA‐based sub‐stage division algorithm is proposed. This algorithm is based on the fact that production transition can be detected by analysing the loading matrixes and principal component matrixes, which reveal objectively evolvement of underlying process behaviours. Sub‐stage PCA models for each stage are built, and then extended to monitor the batch processes with uneven‐length durations by choosing the right sub‐stage model according to the principle of minimum similarity distance of principal component matrixes. With the proposed method, multi‐stage batch processes with durations of uneven‐length can be monitored effectively.     

In‐line and in situ monitoring of semi‐batch emulsion copolymerizations using near‐infrared spectroscopy

This article shows that near‐infrared spectroscopy (NIRS) can be used efficiently for the simultaneous in‐line and in situ monitoring of monomer (methyl methacrylate, MMA, and butyl acrylate, BuA) and polymer concentrations in the reaction medium during seeded semibatch emulsion copolymerizations. A series of actual reaction experiments was planned to allow the proper obtainment and selection of calibrating samples. Partial least squares (PLS) was used to build three independent calibration equations in the range of 1100–1900 nm, which were used to successfully monitor some disturbed reactions in‐line. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2670–2682, 2002     

A low‐energy emulsification batch mixer for concentrated oil‐in‐water emulsions

This work shows the formation of a high internal phase ratio oil‐in‐water (O/W) emulsion using a new type of a two‐rod batch mixer. The mixture components have sharply different viscosities [1/3400 for water‐in‐oil (W/O)], similar densities (1/0.974 for W/O), and an O/W ratio of 91% (wt/wt). The simple design of this mixer leads to a low‐energy process (10⁶ < energy density [J m^?3] < 10⁷), characterized by low rotational speed and laminar flow. The droplet size distribution during the emulsification was investigated according to different physical and formulation parameters such as stirring time (few minutes < t < 1 h), rotational speed (60 < Ω < 120 rpm), surfactant type (Triton X‐405 and X‐100), concentration (from 1 to 15.9 wt % in water), and salt addition (30 g/L). We show that all studied parameters allow a precise control of the droplet size distribution and the rheology. The resulting emulsions are unimodal and the mean droplet diameter is between 30 μm and 8 μm. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Preparation of an organomontmorillonite master batch and its application to high‐temperature‐vulcanized silicone‐rubber systems

N,N‐Di(2‐hydroxyethyl)‐N‐dodecyl‐N‐methyl ammonium chloride was used as an intercalation agent to treat Na⁺‐montmorillonite and form a novel type of organic montmorillonite (OMMT). An OMMT master batch (OMMT‐MB) was prepared by solution intercalation and was used in the preparation of high‐temperature‐vulcanized silicone rubber (HTV‐SR)/OMMT‐MB nanocomposites. The properties, such as the tensile and thermal stability, were researched and compared with those of composites directly incorporated with OMMT or aerosilica. A combination of Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and transmission electron microscopy studies showed that HTV‐SR/OMMT‐MB composites were on the nanometer scale, and their structure was somewhat hindered by the presence of OMMT. The results showed that the tensile properties of HTV‐SR/OMMT‐MB and HTV‐SR/OMMT systems were better than those of pure HTV‐SR. Compared with those of HTV‐SR/OMMT‐20%, the tensile strength and elongation at break of HTV‐SR/OMMT‐MB‐20% were improved about 1.5 and 0.9 times, respectively. This was probably due to the nanoeffect of the exfoliated silicate layers. Moreover, the tensile strength of HTV‐SR/OMMT‐MB‐20% was nearly equal to that of HTV‐SR/aerosilica‐20%, and the elongation at break even showed much improvement. Additionally, the thermal degradation center temperature of the HTV‐SR/OMMT‐MB‐20% nanocomposite was increased by 30°C compared with that of the HTV‐SR/OMMT‐20% composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch,semi‐batch and continuous operation

The removal of single component and binary mixtures of divalent cobalt and iron from water by ion exchange with synthetic Y zeolite has been studied in batch, semi‐batch and continuous modes of operation; the initial metal solution concentration did not exceed 2 mmol dm^?3. Binary Co/Na and Fe/Na ion exchange equilibrium isotherms (294 K) are presented wherein exchange site heterogeneity is evident in the case of the iron treatment. Under conditions of stoichiometric ion exchange, removal efficiencies for both cobalt and iron decrease with increasing metal concentration (0.2–2 mmol dm^?3) and the values were similar for both metals. Removal of cobalt under transient conditions was found to be temperature dependent. In the fixed bed operation, break‐through behavior was sensitive to changes in both flow rate and inlet concentration. The break‐through profiles for both metals under competitive and non‐competitive conditions are presented; iron removal is lower in the presence of cobalt and vice versa. An in situ regeneration of the fully loaded zeolite by back exchange with sodium is considered and the exchange capacity of the regenerated zeolite is reported. The feasibility of employing cycles of heavy metal uptake/zeolite regeneration is addressed. © 2002 Society of Chemical Industry     

Neural Optimization of Fed‐batch Streptokinase Fermentation in a Non‐ideal Bioreactor

Microbial fermentations involving two or more kinds of competing cells and operating under realistic conditions are difficult to monitor, model and optimize by model‐based methods. They deviate from ideal behavior in two significant aspects: incomplete dispersion in the broth and the influx of disturbances. The approach here has been to optimize the filtered noise and dispersion on‐line through neural networks. This method has been applied to the fed‐batch production of streptokinase (SK). The culture has two kinds of cells — active (or productive) and inactive — and their growth is inhibited by the substrate and the primary metabolite (lactic acid). Using simulated data, the fermentation was optimized by a system of three neural networks, updated continually during successive time intervals. Such sequential optimization with dynamic filtering of inflow noise generated better cell growth and SK activity than static optimization and even an ideal fermentation.     

Design of mixed energy‐integrated batch process networks by Pseudo‐direct approach

In this article, a novel framework for the design of mixed (combined direct and indirect) integration for batch process systems is presented. The framework is based on the concept of pseudo‐direct energy integration (PDEI) which reformulates indirect integration as direct integration using pseudo‐process streams. Two algorithms are presented to achieve energy integration for batch processes operating cyclically (in a campaign mode). The first algorithm targets maximization of energy recovery and overcomes the limitations of some of the existing contributions for design of mixed integrated systems. The second algorithm provides a network reduction methodology to generate a cadre of integrated designs while exploring the trade‐off between capital (number of heat exchangers and storage units) and operating costs (utility consumption). The proposed framework is illustrated using a benchmark example of two hot and two cold streams. © 2017 American Institute of Chemical Engineers AIChE J, 63: 55–67, 2018