A detailed mathematical model of the propylene-1-hexene copolymerization based on the two-dimensional probability generation function technique is developed. It calculates the joint molecular weight-copolymer composition distribution (MWD-CCD) of the copolymer, as well as the average copolymer composition distribution, the molecular weight distribution (MWD), the copolymer composition distribution (CCD), average molecular weights and composition, and yield. The parallelized execution of the model code allows for obtaining the different copolymer microstructure distributions efficiently. The model allows for reaching a thorough understanding of the copolymer microstructure under different operating conditions of a semibatch reactor. It also has the potential to become a powerful tool for selecting operating conditions to obtain a material with target molecular properties.

In this work, the synthesis of magnetic microspheres of poly(glycidyl methacrylate-co-divinylbenzene) via suspension polymerization is reported. The concentrations of divinylbenzeneand benzoyl peroxide in the microspheres synthesis are studied. The microspheres, characterized by thermal analysis , scanning electron microscopy, vibrating sample magnetometry , and light scattering detection , show good morphological control and thermal stability. This material presents a narrow size range and an appreciable fraction of superparamagnetic particles. The increase in divinylbenzene concentration can cause a decrease in the mean diameter of the microspheres. On the other hand, the increase in benzoyl peroxide concentration causes an increase in the mean diameter of the microspheres.

Soft sensors (SS) are of importance in monitoring polymerization processes because numerous production and quality variables cannot be measured online. Adaptive SSs are of interest to maintain accurate estimations under disturbances and changes in operating points. This study proposes an adaptive SS to online estimate the mass conversion in the emulsion copolymerization required for the production of Styrene-Butadiene rubber (SBR). The SS includes a bias term calculated from sporadic laboratory measurements. Typically, the bias is updated every time a new laboratory report becomes available, but this strategy leads to unnecessarily frequent bias updates. The SS includes a statistic-based tool to avoid unnecessary bias updates and reduce the variability of the bias with respect to classical approaches. A control chart (CC) for individual determinations combined with an algorithmic Cusum is used to monitor the statistical stability of the average prediction error. The adaptive SS enables a bias update only when a loss of said statistical stability is detected. Several bias update methods are tested on a simulated industrial train of reactors for the latex production in the SBR process. The best results are obtained by combining the proposed CC-based approach with a previously developed Bayesian bias update strategy.

Ethylene/1-hexene copolymerization with two MgCl2-supported Ziegler-Natta catalysts containing no internal electron donor or diethylphthalate (DEP) is conducted for different polymerization time . Effects of DEP on active center distribution are studied by fractionating each copolymer sample into boiling n-heptane soluble (C7-sol) and insoluble (C7-ins) fractions, and counting the number of active centers in the copolymer fractions . The main effect of introducing DEP in the catalyst are reduction in the Ti content and significant increase in the proportion of active centers producing C7-ins fraction. The propagation rate constants of ethylene insertion (kpE) and 1-hexene insertion (kpH) are respectively estimated by linear fitting/extrapolating the change of apparent propagation rate constants (kpi)a with polymer yield according to a simplified multi-grain particle model. In both catalysts, kpE in the C7-ins fraction is 9–12 times larger than that in the C7-sol fraction, and kpH in the C7-ins fraction is 3–4 times larger than that in the C7-sol fraction. The two groups of active centers have distinctly different catalytic properties. Introducing DEP reduced the kpE and kpH values and the extent of diffusion limitation . In summary, addition of electron donor in MgCl2-supported Z-N catalyst significantly changed the active center distribution and catalytic properties of its two groups of active centers.

This paper builds on the theoretical framework of the previous articles on the solubility of vapors in semicrystalline polyethylenes produced in the gas phase process. The present article clarifies the theoretical basis for an activity coefficient approach, which results from a constraint on the amorphous phase within semicrystalline polymers. This concept is coupled to an advanced equation of state for use in polyolefin reaction engineering, and presented in a modular way the procedure for computing the requisite thermodynamic quantities. A temperature dependence on polymer crystallinity is also introduced. In the interest of developing a more predictive model for solubility, the model using single pure gas isotherms are parameterized. The results demonstrate the ability to predict single and mixed gas absorption, including new data published herein. The validity of the model is further demonstrated through comparisons with literature studies on batch scale ethylene polymerization. Finally, how a simple correlation to standard polymer characteristics yields accurate predictions in the absence of measured data for parametrization is demonstrated.

In this paper, a detailed description of particle adsorption/diffusion model in batch systems is presented. The phenomenological equations are based on a mechanism combining mass transfer by convection from bulk phase to particle surface, intraparticle mass diffusion and equilibrium adsorption processes. The change of bulk and particle concentration is modeled through differential mass balance equations, leading to a system of one ordinary differential equation and one partial differential equation. When adsorption equilibrium follows a linear relationship, this system of equations can be solved by the Laplace transform method. The purpose of this paper is the development of a generalized analytical solution, that is rewritten specifically for each of the traditional particle shapes: slab, cylinder, and sphere. Finally, this analytical solution is evaluated through several simulations in different batch conditions and compared to simulated experimental data, showing the capability of this analytical solution to predict batch adsorption processes when adsorbate concentration is low. This result clearly indicates the feasibility of applying the analytical solution presented in this paper, which is based on phenomenological concepts, to describe the adsorption kinetics of processes, when the linear isotherm can be considered adequate to represent the adsorption equilibrium.

In high-pressure free-radical ethylene polymerization tubular reactors, fouling often occurs due to polymer deposition onto the reactor's wall surface. This results in a decrease in the overall heat transfer coefficient. Note that a high-pressure tubular reactor must be capable of removing about half of the generated polymerization heat to the cooling water flowing into the reactor's jackets. Therefore, reactor fouling can have serious implications including decrease of heat removal rate and monomer conversion, increase in the overall initiator(s) consumption, change of polymer quality, decline of reactor's safe operation, and significant economic losses due to lower plant productivity and longer reactor maintenance periods. In rare cases, the loss of reactor's heat removal capacity may result in the appearance of local hot spots that eventually can trigger ethylene decomposition. In the present review paper, the fundamental physical and chemical phenomena regarding polymer fouling and ethylene decomposition in high-pressure low density polyethylene (LDPE) reactors are critically discussed. The effects of shear rate, polymer molecular weight, and wall surface energy on polymer adsorption and desorption are analyzed. Moreover, the effect of characteristic initiator decomposition and micromixing times and process conditions on initiator dispersion, polymer fouling, and ethylene decomposition are assessed.

Front Cover: This study deals with the development of a reaction kinetic model describing the inhibition mechanism of RAFT dispersion polymerization by oxygen and its application to investigate the effect of re-initiation on the synthesized polymer quality. The experimental validation of the kinetic model creates a functional digital twin, establishing a valid method for diblock copolymer synthesis from a non-successful polymerization attempt. This is reported by Emil Pashayev, Felix Kandelhard, and Prokopios Georgopanos in article number 2200068.

The mechanical properties and blocking resistance of films cast from latex particles can be improved by addition of a reinforcing polymer of high modulus that acts as a “hard” phase. This work demonstrates that blocking resistance, a key performance parameter for use in coatings, of such films can be understood in terms of the relative contribution of the “hard” and “soft” components to the rheological properties of the material. In order to do so, representative latexes that contain a semicrystalline core of poly(stearyl acrylate) as a reinforcing phase and a shell of amorphous poly(styrene-co-butyl acrylate) are synthesized. By varying the composition of the amorphous phase (glass transition temperature, molar mass) and the relative amorphous/semicrystalline fraction, it is demonstrated that the improvement in blocking resistance is strongly correlated with the increase in the modulus of the material but is also affected by the dynamics of polymer diffusion of chains in the soft phase. This work allows to establish design rules for polymer and colloidal structures that can be targeted to maximize blocking resistance.

Polybutylene succinate (PBS) and other succinic (co)polyesters are biodegradable polymers with favorable mechanical and thermal properties that find use in many applications. Due to environmental concerns, polymers based on succinic acid (SA) have been gaining attention, as SA can be produced through biotechnological processes. Thus, this review aims to highlight the synthesis and characteristics of PBS and other succinic copolyesters, with emphasis in the works employing metallic catalysts and enzymes. In addition, the modification of the macromolecular structure by copolymerization or postpolymerization is also discussed. Currently, metallic catalysts are normally used in the synthesis of these materials, under conditions of high temperatures, which can favor the occurrence of thermal degradation, increasing the dispersion of chain length distributions. Moreover, the incrustation of metallic catalysts in polymeric materials makes their application in biomedical products difficult, due to toxicity requirements. In this context, enzymatic catalysis is gaining ground, offering milder synthesis temperatures, high selectivity, and uniformity of synthesized products. This biotechnological route can substitute oligomerization processes with metallic catalysis in future industrial processes, producing materials free from metallic contamination. In addition to production by catalytic routes, trends for future applications of succinic (co)polyesters are presented, with emphasis on the value-added materials sectors.

I am pleased to celebrate the 60th birthday of our colleague and friend, Tim McKenna, in this special issue of Macromolecular Reaction Engineering (MRE). I am also thrilled that I am not the only one to reach this milestone, even though I preceded him by a couple of years. Welcome to the club, old man. The number and scope of articles submitted to this special MRE issue reflect Tim's many accomplishments in polymer reaction engineering. Tim is the Director of Research of CP2M/CNRS and a Professor at CPE-Lyon in Villeurbanne, France. Tim's research program applies chemical engineering tools to understand, quantify, and control polymerization reactors, focusing on polyolefins and specialized latex products. He has published 269 peer-reviewed articles, 12 book chapters, 1 authored book, and is listed as an inventor in 6 patents. Tim has also given many keynote lectures and invited presentations in international conferences, and supervised a multitude of graduate students who are currently contributing to different areas of polymer science and engineering. He has also organized several international conferences, most notably Incorep (International Conference on the Reaction Engineering of Polyolefins), previously known as Ecorep (European Conference on the Reaction Engineering of Polyolefins), which will become the Blue Sky-Incorep conference in 2023, combining by the first time aspects of polyolefin chemistry, catalysis, and reaction engineering. Tim is also highly sought after as a consultant and as an expert witness for the polymer industry. I was lucky to meet Tim when we were still at the beginning of our academic careers. If memory doesn't fail me—as it's prone to do after one's 60th birthday—we first met in 1997, in Palm Coast, Florida, while attending Polymer Reaction Engineering III. Tim was interested on improving single particle models for olefin polymerization, focusing on intraparticle transport phenomena, particle morphology development, and thermodynamic equilibrium, while I was integrating polymerization kinetics and microstructural characterization methods to better understand olefin polymerization with coordination catalysts. Luckily for us, our research interests superimposed just enough to foster collaboration but not to trigger the shadow of competition that haunts young academics. This first meeting led to a lifelong collaboration—including our book, Polyolefin Reaction Engineering, and a series of open and in-house industrial short courses—allowing us to visit most major polyolefin manufacturing companies and travel the world together. But I suspect that work alone would not be enough to maintain our friendship over the years. Research interests aside, Tim and I are both liberal humanists who share a love for single malts, good wines, long dinners capped with perhaps a few too many poires, and an irreverent sense of humor. Above all, we don't confuse being serious about our work with taking ourselves too seriously. It has been a privilege to have met a friend like Tim at the beginning of my career. I generally don't admit this in public, and never in his presence, but I have learned and benefited much from his expertise over these almost 30 years of collaboration. For all your many achievements and enduring friendship, I would like to raise a toast to you, my old friend, and wish you a very happy 60th birthday on behalf of all the authors in this special issue. I look forward to working with you until both of us forget what a bivariate distribution is. (But, have you ever really understood it, Tim?) Tim Mckenna and I (the older-looking guy is Tim) in 2017, experiencing a Game of Thrones moment in Sonoma Valley, irresponsibly skipping a few talks during Advances in Polyolefins.

Hybrid non-isocyanate poly(urethanes) (HNIPUs) are designed from a precursor whose carbonate functionality is derived from epoxy-functional statistical copolymers. Specifically, a bio-based diene (β-myrcene) is copolymerized via conventional free radical polymerization with glycidyl methacrylate (GMA) at different molar ratios, producing flexible copolymers with epoxy pendant groups, which are then reacted with carbon dioxide to yield the precursors with cyclic carbonate functionality. Subsequent addition of an amine-terminated telechelic poly(propylene glycol) (PPG) forms urethane linkages in the side chains, whose concentration is tuned by varying the GMA initial molar fraction. The NIPUs are end-capped with silanes to enable moisture curing, resulting in HNIPUs with elongations at break up to 150%, and relatively low elastic moduli varying from 32 kPa to 50 kPa as the number of urethane side linkages increases from 6 to 22. The swelling ratio of the NIPUs is also measured in tetrahydrofuran (THF). As the number of urethane side chains increases, the swelling ratio of the NIPUs decreases (710% to 620%), indicating a higher crosslinking density. All samples have gel contents higher than 50% in THF, indicating non-crosslinked species in the hybrid samples which confirms the relatively low reported tensile moduli.

The present work presents phenomenological models to describe the coordination polymerization of β-myrcene using the Ziegler–Natta catalyst system composed by neodymium versatate (NdV3), diisobutylaluminum hydride (DIBAH), and dimethyldichlorosilane. The kinetic parameters required to simulate the reactions are estimated, and the amount of DIBAH used as a chain transfer agent (CTA) is obtained by a data reconciliation strategy since it can participate in side reactions. Several experiments are performed at different conditions to evaluate the impact of key operation variables on the control of monomer conversion and average molar masses. It is shown that the initial NdV3, β-myrcene, and DIBAH concentrations exert strong influences on the course of the polymerization. The kinetic mechanism of Coordinative Chain Transfer Polymerization (CCTP) fits well with the data of final average molar masses and monomer conversion, while the dynamic trajectories of these variables are fitted better by kinetic mechanisms of more conventional coordination polymerizations, considering site deactivation and termination by chain transfer. In all cases, the proposed models are able to predict the experimental data well after successful parameter estimation and reconciliation of CTA concentrations, indicating that the kinetic mechanism can be characterized by different kinetic regimes.

The current work describes the synthesis of a new polyHIPE-like sulfonated poly(styrene-co-n-acylglycerol) and its use as an efficient heterogeneous catalyst to convert oleic acid into methyl oleate in esterification reactions. This new environmentally friendly polymer incorporates n-acylglycerol macromonomer as a versatile strategy for glycerol valorization. Macroporous micrometric polymer particles are synthesized through suspension polymerization process without using porogenic agents. polyHIPE-like copolymers formed with different feed compositions of styrene and n-acylglycerol are chemically modified via sulfonation reactions to form a highly efficient catalyst for esterification of oleic acid to methyl oleate, exhibiting conversions lying in the interval from 52% to 96%, depending mainly on the amount of n-acylglycerol macromonomer into the copolymer chains. The experimental results indicate the great potential of this new heterogeneous catalyst based on modified poly(styrene-co-n-acylglycerol) to be successfully employed in esterification reactions of vegetable oils intended for the production of long chain alkyl esters of carboxylic acids, widely used as biofuels.

Low salinity water–polymer flooding (LSWPF) is an emerging hybrid enhanced oil recovery (EOR) method that uses the synergetic effects of low salinity water (LSW) and polymers to enhance both the microscopic and macroscopic sweep efficiencies. Polymer flooding is an EOR method that aims to increase water viscosity and improve the mobility ratio of the injected fluid to the reservoir. It enhances mobility control and reduces water relative permeability, reaching a more favorable condition for sweep efficiency. LSW is an EOR method that aims to change wettability by exploiting crude oil and reservoir rock interactions. It allows for improving oil recovery when the injected water has a very low salinity compared to seawater or formation water. The literature reports LSWPF studies applied to sandstone reservoirs. However, LSWPF applications in carbonate reservoirs still lack. This review critically analyzes LSWPF as an alternative to Polymer flooding using seawater in carbonate reservoirs.

In this work, novel imido-Cr/silica catalysts are synthesized by modifying the Phillips catalyst CrOx/silica with isocyanates. The imido-Cr/silica, which has moderate activities of 200–300 kgPE molCr−1 bar−1, shows lower efficiency than CrOx/silica for C2H4 polymerization. On the other hand, regarding to the modified catalysts, the productivity can be improved almost linearly with increasing C2H4 pressure, and very stable activities are observed during the 1 h run of C2H4 polymerization. When compared with CrOx/silica, the modified catalysts can produce polyethylene (PE) with much higher molecular weight (MW) and broader molecular weight distribution (MWD), which is featured by a distinct ultrahigh MW shoulder. Meanwhile, the MW and MWD of the PE products can be reduced obviously by adding a small amount of H2 before C2H4 polymerization. In addition, it is found that more 1-hexene can be copolymerized by CrOx/silica, and it is preferentially incorporated into a portion of the PE chains. While such a preference is much less significant for the modified catalysts.

Deposit formation and fouling in reactors for polymer production and processing especially in microreactors is a well-known phenomenon. Despite the flow and pressure loss optimized static mixers, fouling occurs on the surfaces of the mixer elements. To improve the performance of such parts even further, stainless steel substrates are coated with ultra-thin films which have low surface energy, good adhesion, and high durability. Perfluorinated organosilane (FOTS) films deposited via chemical vapor deposition (CVD) are compared with FOTS containing zirconium oxide sol-gel films regarding the prevention of deposit formation and fouling during polymerization processes in microreactors. Both film structures led to anti-adhesive properties of microreactor component surfaces during aqueous poly(vinylpyrrolidone) (PVP) synthesis. To determine the morphology and surface chemistry of the coatings, different characterization methods such as X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy as well as microscopic methods such as field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) are applied. The surface free energy and wetting properties are analyzed by means of contact angle measurements. The application of thin film-coated mixing elements in a microreactor demonstrates a significant lowering in pressure increase caused by a reduced deposit formation.

One approach used in the industry to improve the properties of polyethylene is to use multi-reactor with a single catalyst or multiple catalysts in a single reactor. In the latter case, two catalysts with distinct kinetics are selected to achieve the desired product properties. Such mixed catalyst systems enable tailored and advantageous properties at the cost of more challenging process control, because the ratio of the two catalysts serves as an additional manipulated variable. A fast method to estimate the ratio of active catalysts using headspace gas chromatography measurements is proposed here. In this method, a small perturbation in the feed rate is introduced to induce transient responses in the gas phase concentration. Ideally, with known responses from each individual catalyst, the active catalyst ratio can be estimated. To demonstrate this concept, a process model is developed in Aspen Plus. A set of dynamic simulation is performed to understand the responses of each catalyst and the mixed catalyst system, to changes in feed comonomer concentration. The results demonstrate that this method has significantly faster responses compared to feedback from bulk polymer properties and induces minimal process upset or product off-spec due to small perturbations in a short period of time.

The sustainability of consumer materials, such as plastics, belongs to the most important aspect of eco-efficiency analyses. Besides mechanical recycling, chemical recycling represents an interesting waste management pathway. In theory, this technique does not rely on single-grade feedstock to maintain product quality. However, cross-contamination of feedstocks potentially leads to above-specification impurities in obtained pyrolysis oils. This study investigates the potential downstream poisoning of a fourth-generation Ziegler-Natta catalyst, using selected model poisons at high (worst-case) concentrations. With experimental and computational analysis, economic feasibility factors such as catalyst activity and microstructural properties are evaluated during the synthesis of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE). Noticeable effects on the catalyst activity can be observed when the poison interacts with the co-catalyst, whereas a lower impact is observed for interactions with the activated catalyst-co-catalyst complex. Molecular weight distribution (MWD) and comonomer composition distribution (CCD) modeling highlighted marginal to no polymer property changes caused by contaminants. Combined with the applicability of pyrolysis post-treatments, these observations show that chemical recycling can be a promising technique for post-consumer plastic waste treatment.

Pollution by plastics constitutes an urgent problem that demands immediate actions, including development of efficient polymer recycling technologies. In this scenario, the catalytic degradation of plastic wastes constitutes a promising technology, as suitable catalysts can be used to perform cracking reactions and controlled plastic degradation, yielding high quality end products. Catalyst investments are expected to be recovered by benefits related to reduction of reaction temperature and time and by manufacture of higher valued products. However, proper environmental assessment of catalyst usage has yet to be performed in most plastics chemical recycling processes. For these reasons, in the present study, life cycle assessment (LCA) based on system expansion methodologies is carried out to determine the environmental impacts of catalytic pyrolysis transformations of high-impact polystyrene (HIPS) and high-density polyethylene (HDPE) using zeolite H-USY (ultrastable Y) and SO4/SnO2 catalysts, respectively, based on actual collected experimental data to represent conversions and yields. Surprisingly, the obtained results indicate that the use of catalysts for plastic waste degradation reactions can be environmentally disadvantageous sometimes, depending on the blend of obtained products. Therefore, the environmental impact of catalysts on plastics chemical recycling should be carefully assessed to avoid problems derived from positive bias, which assumes that the catalytic process is necessarily better than the noncatalytic counterpart. However, the positive impacts of styrene and olefins recovery can indeed contribute with positive environmental performances of both catalytic and non-catalytic processes, particularly regarding global warming, acidification, human toxicity, ecotoxicity, eutrophication, and ozone layer depletion.