Polymerization Of Styrene Research Articles

A Case Study on Online Estimation of Polystyrene Formation Runaway Reaction Process Parameters

Batch reactors with polymerisation reaction and ineffective cooling arrangements are prone to thermal runaway. In the present case study, we have investigated such a thermal runaway scenario in case of thermally initiated free radical styrene polymerisation reaction inside adiabatic and non-adiabatic batch reactors. We found that our developed process model for the well-mixed batch reactor along with the reported kinetic model in the literature; aptly describes the thermal runaway polystyrene formation reaction conditions (critical temperature for runaway, Tcr and the critical time for runaway, tcr). We have also deployed the well-studied Extended Kalman Observer (EKO) to provide online estimates of the runaway reaction process parameters, by using reaction temperature as the only measurement to the observer. It is noted that the non-linear EKO with this one temperature measurement provides accurate estimates of all runaway process parameters from an early time interval. We have also shown that an accurate online estimate of the critical process variables of the polystyrene formation reaction by using the EKO algorithm helps in effective manipulation of initiator concentration that increases the operational safety of the non-adiabatic batch reactors by delaying the attainment of Tcr at a higher monomer conversion.

Numerical Analysis of Industrial Styrene Polymerization in Nonideal Tower Reactors

Numerical Analysis of Industrial Styrene Polymerization in Nonideal Tower Reactors

Synthesis of Dimpled Particles by Seeded Emulsion Polymerization and Their Application in Superhydrophobic Coatings.

Dimpled particles are synthesized through the seeded polymerization of fluoroacrylate and styrene on swelled polystyrene spheres. The morphologies of the particles can be controlled by the polymerization temperature, the amount of solvent swelling the seeds or the ratio of the fluoroacrylate monomer over styrene. Golf-ball-like particles with many small dimples on their surfaces are obtained at low polymerization temperatures or with a small amount of solvent. Particles with a large single dimple are formed at higher polymerization temperatures, with larger solvent amounts or a higher ratio of fluoroacrylate over styrene. The morphology formation mechanism of these dimpled particles is proposed and the application of these particles in the fabrication of superhydrophobic coatings is demonstrated.

Comparing pellet‐ and filament‐based additive manufacturing with conventional processing for ABS and PLA parts

AbstractMore recently pellet‐based additive manufacturing or so‐called micro‐extrusion has become more popular for final polymeric part production. In the present work, it is evaluated how pellet‐based AM (PBAM) performs for its extrudates and specimens compared to the more established fused filament fabrication technique, considering both commercial acrylonitrile butadiene styrene polymer and poly(lactic acid) pellets and filaments as feedstocks. For benchmarking purposes, a comparison with conventional techniques, that is, single screw extrusion and injection molding, is also included. To support the performance interpretation a theoretical analysis is conducted regarding the melting finalization point as well as void measurements and Fourier transfer infrared spectroscopic analysis for degradation effects are included. It is demonstrated that for the extrudates comparable results are obtained among the different manufacturing techniques, whereas for the specimens the situation is dissimilar. It is highlighted that PBAM/ME has a large market potential implementation, provided that its operating settings are further optimized.

A Xanthate-Type Photofunctional Chain Transfer Agent for the Synthesis of Macrophotoinitiators

Polystyrene (PSt), poly(methyl methacrylate) (PMMA), and poly(vinyl acetate) (PVAc) macrophotoinitiators with well-defined structures comprising a photoreactive group, benzoin (B), at the chain end were successfully synthesized by RAFT/MADIX polymerization. First, a photofunctional xanthate-type chain transfer agent (B-CTA) was produced by an efficient two-step one-pot synthesis. Then, B-CTA was used in the RAFT/MADIX polymerization of styrene (St), methyl methacrylate (MMA), acrylonitrile (AN) (more activated monomers), and vinyl acetate (VAc) (a less activated monomer). Based on spectral and GPC data, the RAFT/MADIX polymerizations of St, MMA, and VAc monomers produced well-controlled macrophotoinitiators with narrow molecular weight distributions and compatible theoretical and experimental number-average molecular weights. The resulting well-defined macrophotoinitiators, B-PSt, B-PMMA, and B-PAVc, were used as precursors to obtain block copolymers PSt-b-PCHO, PMMA-b-PCHO, PVAc-b-PCHO from cyclohexene oxide (CHO) and PSt-b-PBVE, PMMA-b-PBVE, PVAc-b-PBVE from butyl vinyl ether (BVE) monomers, respectively, via photoinduced free radical promoted cationic polymerization. Various analyses such as elemental, spectroscopic, and GPC techniques were used to confirm the structures of the synthesized molecules.

Poly(acrylic acid) block copolymers as stabilizers for dispersion polymerization

Dispersion polymerization stabilized with poly(acrylic acid) has been performed for decades to produce polymer particles whose surfaces are modified with pH-responsive poly(acrylic acid) moieties. To improve stabilizer efficiency, poly(acrylic acid) block copolymers, in which a poly(acrylic acid) chain is attached to the terminus of a polystyrene or PMMA chain, were used as stabilizers for the dispersion polymerization of styrene or MMA. Compared with the poly(acrylic acid) homopolymer, polystyrene-block-poly(acrylic acid) was found to improve the controllable ranges of particle size and the carboxylic-acid-group surface density of the resulting polystyrene particles. Furthermore, we also investigated the effect of heterogeneity between the polymer species of the particle core and the attached polystyrene or PMMA chains in the poly(acrylic acid) block copolymers. Finally, we also examined the applicability of polystyrene-block-poly(acrylic acid) as a stabilizer and surface modifier for the dispersion polymerization of various monomers.

Investigation of Polyurethane Modified Cold Bitumen for Fast Cold In-Place Recycling

Cold in-place recycling is gaining more attention worldwide because of its lower energy consumption, while the normally used asphalt emulsion and foamed asphalt cannot meet this requirement of short traffic disturbance and road performance of the surface layer. In this research, a polyurethane-modified cold binder (PMCB) was designed and investigated for the fast and high-quality cold in-place recycling of reclaimed asphalt. For the first step, functional group analysis and fluorescent microscopy were used to reveal the curing process and the modification mechanism of the PMCB. Then a series of rheological tests were used to comprehensively evaluate the viscoelastic properties of the PMCB at different curing stages. Finally, the mechanical performance of the PMCB mortar sample was evaluated with the monotonic tensile test and tensile fatigue test. The results indicated that the polymerization reaction in the PMCB consisted of three reactions, and the urethane/urea linkage led to the formation of the polymeric network. The polyurethane polymeric network led to a significant increase in the complex modulus and a decrease of the phase angle. The PMCB also exhibits suitable viscosity at environmental temperatures, good relaxation properties at low temperatures, and less temperature sensitivity. Compared to the base asphalt and styrene butadiene styrene polymer modified bitumen mortar samples, the PMCB mortar samples showed significant advantages in tensile strength, dissipation energy, and tensile fatigue properties. Furthermore, the polyurethane-modified cold asphalt mixture (PMCM) showed better indirect tensile strength than the porous asphalt mixture with fresh aggregate and fresh asphalt binder when the curing time of the PMCM reached 6 h.

Evaluation of biocathode materials for microbial electrosynthesis of methane and acetate

This study compares carbon felt (CF), granular activated carbon (GAC), and a conductive acrylonitrile butadiene styrene (cABS) polymer cathodes for CH4 and acetate production in a microbial electrosynthesis (MES) cell. At an applied voltage of 2.8 V and continuous CO2 flow, the CF biocathode MES cell showed the highest CH4 production rate of 1420 ± 225 mL Vc-1 d-1 (Vc = cathode volume), also producing acetate at a rate of 710 ± 110 mg Vc-1 d-1. The volumetric rates of acetate and CH4 production decreased when using the GAC cathode (720 ± 94 mL Vc-1 d-1 and 236 ± 65 mg Vc-1 d-1, respectively). When the cABS cathode was used, the CH4 production declined to 250 ± 35 mL Vc-1 d-1, while the acetate production increased to 1105 ± 130 mg Vc-1 d-1. The biocatalytic activity of cABS increased after in-situ electrodeposition of Ni and Fe, resulting in a current increase from 205 mA to 380 mA accompanied by increasing acetate and ethanol production (1405 mg Vc-1 d-1 and 240 mg Vc-1 d-1, respectively), while the CH4 production decreased. The cABS cathode showed the highest specific (per surface area) activity for acetate and CH4 production.

Fatigue and fracture of additively manufactured polyethylene terephthalate glycol and acrylonitrile butadiene styrene polymers

This paper aims to study and compare the static tensile properties and Low Cycle Fatigue (LCF) deformation behavior of Additively Manufactured (AM) samples made of two commonly used polymers: Polyethylene Terephthalate Glycol (PET-G) and Acrylonitrile Butadiene Styrene (ABS). Such materials are commonly in use in the Material Extrusion (ME) AM technologies – especially in Fused Deposition Modelling (FDM) or Fused Filament Fabrication (FFF). That kind of approach would be useful to understand the fracture phenomena of AM parts obtained by means of FDM/FFF technologies which are entirely different than in the conventionally made material, because of the characteristic layered structure of AM parts. The study has been supplemented by additional fracture analysis of AM samples subjected to LCF tests. The conducted research exposed an increased LCF of PET-G samples (36050 cycles at constant strain equal to ε = 0.40%) in comparison to ABS (24586 cycles at the same strain level). At the same time, PET-G samples indicated a significant material softening during LCF testing. Such a phenomenon was better described by additional analysis with the use of the Morrow equation which indicated quasi-brittle cracking with visible brittle fracture phenomena in PET-G samples.

Process hazard evaluation and thermal runaway prediction for styrene polymerization initiated by peroxide-azo composites

Styrene is an important monomer for synthetic resins, ion exchange resins and synthetic rubber. Styrene polymerization requires the use of initiators to increase the reaction rate, with composite initiators showing promise for increased reaction rates. However, increased reaction rates in polymerization, if uncontrolled, can lead to thermal runaway with disastrous consequences. Numerous runaway incidents have been documented, indicating inadequate awareness of the thermal hazards of polymerization reactions. This study focuses on determining via calorimetric techniques the thermal hazards of styrene polymerization using azodiisobutyronitrile (AIBN) and tert-Butyl peroxybenzoate (TBPB) composite initiators. Differential scanning calorimetry (DSC) is employed to investigate the thermal decomposition properties of composite initiators with varying composition. Non-isothermal experiments and adiabatic experiments are used to determine the thermal hazard parameters including initial exothermic temperature and heat release of styrene polymerization. The risk of secondary reactions is evaluated by reaction calorimetry (RC1e) and product thermogravimetric analysis (TGA). Key safety parameters of the exothermic reaction, such as the onset temperature, heat release, time to maximum rate under adiabatic condition as well as activation energy, are presented. The results show that the thermal hazard of the polymerization reaction is lowest when the ratio of AIBN to TPPB in the composite initiator is 1:1. In this scenario, the temperature reached by the uncontrolled reaction does not provoke the decomposition of the products, yet the runaway consequences are still unacceptable. This work provides extensive data as a reference for the process optimization of styrene polymerization from the perspective of safety.

Migration of styrene oligomers from food contact materials: in silico prediction of possible genotoxicity

Styrene oligomers (SO) are well-known side products formed during styrene polymerization. They consist mainly of dimers (SD) and trimers (ST) that have been shown to be still residual in polystyrene (PS) materials. In this study migration of SO from PS into sunflower oil at temperatures between 5 and 70 °C and contact times between 0.5 h and 10 days was investigated. In addition, the contents of SD and ST in the fatty foodstuffs créme fraiche and coffee cream, which are typically enwrapped in PS, were measured and the amounts detected (of up to 0.123 mg/kg food) were compared to literature data. From this comparison, it became evident, that the levels of SO migrating from PS packaging into real food call for a comprehensive risk assessment. As a first step towards this direction, possible genotoxicity has to be addressed. Due to technical and experimental limitations, however, the few existing in vitro tests available are unsuited to provide a clear picture. In order to reduce uncertainty of these in vitro tests, four different knowledge and statistics-based in silico tools were applied to such SO that are known to migrate into food. Except for SD4 all evaluated SD and ST showed no alert for genotoxicity. For SD4, either the predictions were inconclusive or the substance was assigned as being out of the chemical space (out of domain) of the respective in silico tool. Therefore, the absence of genotoxicity of SD4 requires additional experimental proof. Apart from SD4, in silico studies supported the limited in vitro data that indicated the absence of genotoxicity of SO. In conclusion, the overall migration of all SO together into food of up to 50 µg/kg does not raise any health concerns, given the currently available in silico and in vitro data.

Polystyrene-Modulated Polypyrrole to Achieve Controllable Electromagnetic-Wave Absorption with Enhanced Environmental Stability.

The moderation of the dielectric properties of polymer composites and their environmental stability need to be considered comprehensively in the design of microwave-absorbing materials. In this work, polypyrrole/polystyrene (PPy/PS) composited particles were synthesized through a facile in situ bulk polymerization procedure. The PS component can be modulated conveniently by controlling the polymerization time. FTIR and Raman analyses disclosed that the PS component was immobilized in PPy via covalent bonds. The electromagnetic characterization results indicated that the dielectric properties and, thus, the microwave absorption could be controlled when the styrene polymerization was prolonged from 6 h (PPy-6) to 19 h (PPy-19). The composite PPy-19 displayed an optimal reflection loss of −51.7 dB with a matching thickness of 3.16 mm, and the effective absorption bandwidth (EAB) even reached 5.8 GHz at 2.4 mm. The PS component endowed PPy/PS composites with more robust environmental stability than homogeneous PPy. After being exposed to air for 365 days and hydrothermally treated at 100 °C for 12 h, PPy-19 still exhibited a reflection loss superior to −20 dB. The present work provides a new insight into the adjustment of the electromagnetic properties of PPy composites to fabricate high-performance microwave absorbers with superior environmental stability.

Modeling Polystyrene Homogeneous‐Coagulative Nucleation in Pickering Emulsion Polymerization

AbstractInvestigation of particle nucleation in surfactant‐free emulsion polymerization of styrene using Laponite clay as Pickering stabilizer is considered. The effective number of clay platelets contributing to the surface charge of the polymer particles is calculated, and used to estimate their stabilizing efficiency. A coagulative nucleation mechanism is proposed and the coagulation coefficient is calculated using the Derjaguin–Landau–Verwey–Overbeek theory. The Hamaker constant involved in the attractive potential of the clay‐polymer composite particles is measured experimentally. The model is found to fit the experimental data in terms of the number of nucleated particles and the nucleation period. The effective number of clay platelets contributing to the surface charge is found higher than the number of platelets allowing full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation requires almost complete coverage.

Customized Orthogonal Solvent System with Various Hole-Transporting Polymers for Highly Reproducible Solution-Processable Organic Light-Emitting Diodes.

Recently, various hosts and emitters for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) have been developed. However, a few studies have been conducted on hole transport materials (HTMs) with differentiated solubility characteristics for manufacturing multilayer OLEDs using a solution process. Here, three new hole transport (HT) styrene polymers, PICz, PPBCz, and PTPCz, were synthesized by radical polymerization. Each of the polymers exhibited increases in their highest occupied molecular orbital (HOMO) levels and better hole-transporting abilities than poly(9-vinylcarbazole) (PVK) as a reference HT polymer. Furthermore, the three HT polymers exhibited different solubilities in toluene. Therefore, it was not possible to use a toluene solution to prepare the emitting layer (EML). To overcome this problem, ethyl acetate (EA), in which the three HT polymers are insoluble, was used as an orthogonal solvent to prepare an EML solution. In EA-solution-processed green-emitting TADF-OLEDs, the three HT-polymer-based devices displayed somewhat low turn-on voltages of 2.8 V and high external quantum efficiencies (EQEs) of >23%. These values are superior to those of a device with a PVK-HT layer. In addition, the devices manufactured with the EA solution showed high-performance reproducibility owing to the stable formation of each layer. In this study, we removed the HTM solubility constraint by dramatically changing the solvent for preparing the EML solution and provided an efficient strategy for the fabrication of OLED devices via solution processes in the future.

Regioselective Seeded Polymerization in Block Copolymer Nanoparticles: Post‐Assembly Control of Colloidal Features

AbstractPost‐assembly modifications are efficient tools to adjust colloidal features of block copolymer (BCP) particles. However, existing methods often address particle shape, morphology, and chemical functionality individually. For simultaneous control, we transferred the concept of seeded polymerization to phase separated BCP particles. Key to our approach is the regioselective polymerization of (functional) monomers inside specific BCP domains. This was demonstrated in striped PS‐b‐P2VP ellipsoids. Here, polymerization of styrene preferably occurs in PS domains and increases PS lamellar thickness up to 5‐fold. The resulting asymmetric lamellar morphology also changes the particle shape, i.e., increases the aspect ratio. Using 4‐vinylbenzyl azide as co‐monomer, azides as chemical functionalities can be added selectively to the PS domains. Overall, our simple and versatile method gives access to various multifunctional BCP colloids from a single batch of pre‐formed particles.

Regioselective Seeded Polymerization in Block Copolymer Nanoparticles: Post-Assembly Control of Colloidal Features.

Post‐assembly modifications are efficient tools to adjust colloidal features of block copolymer (BCP) particles. However, existing methods often address particle shape, morphology, and chemical functionality individually. For simultaneous control, we transferred the concept of seeded polymerization to phase separated BCP particles. Key to our approach is the regioselective polymerization of (functional) monomers inside specific BCP domains. This was demonstrated in striped PS‐b‐P2VP ellipsoids. Here, polymerization of styrene preferably occurs in PS domains and increases PS lamellar thickness up to 5‐fold. The resulting asymmetric lamellar morphology also changes the particle shape, i.e., increases the aspect ratio. Using 4‐vinylbenzyl azide as co‐monomer, azides as chemical functionalities can be added selectively to the PS domains. Overall, our simple and versatile method gives access to various multifunctional BCP colloids from a single batch of pre‐formed particles.

ABS - CaSO4 Polymer Composite: Experimental Studies On Mechanical And Tribological Properties

Objectives: The present study examines the effect of Calcium Sulphate (CaSO4) microparticles as filler materials and ABS as matrix materials on mechanical properties and wear performance of composite materials, which are injected into molds for preparation of the specimens. Methods: The CaSO4 microparticles are added at different weight fractions to the acrylonitrile butadiene styrene (ABS) polymer composites. Moreover, the reinforcement has improved tensile strength, wear properties, and hardness. Wear behavior was measured on ABS/ CaSO4 by a wear monitor (ASTM G99) and pin-ondisc type friction. As part of this experiment, the cutting speed, loading, and sliding distance of composite materials are considered and optimized for their properties. To observe and analyze the characteristics of this material, tensile strength and wear tests were conducted. By analyzing SEM images, we were able to study the fractured material’s morphology. In this study, an orthogonal array (L9) and control parameters were used to examine wear debris that explored the flacks and grooves of the content. Findings: An increase in toughness and modulus of resilience (due to an increase in filler content) and the contribution of normal load to wear rate (37.44%) constitute the most important contribution to work. Novelty : we have evaluated the various tribological and mechanical properties of polymer composite specimens using the Taguchi method. Keywords: ABS; Tensile strength; Pinondisc; SEM; Taguchi

Performance Enhancement of Polymerized, Functionalized Solution Styrene–Butadiene Rubber Composites Using Oligomeric Resin towards Extremely Safe and Energy-Saving Tires

Polymerized, functionalized solution styrene–butadiene rubber (F-SSBR) is a new type of polymerized styrene–butadiene rubber solution containing specific terminal groups, which can be used in treads for high performances. However, the wet skid resistance related to safety, the rolling resistance to energy consumption, and the wear resistance to service life are often contradictory and form the performance “magic triangle”. In this work, oligomeric resins, including Coumarone resin, C9 resin, C5/C9 resin and a styrene-α-methyl styrene copolymer (SSC), were used as tire functional additives and selected to replace treated distillate aromatic extract (TDAE) to improve the performances of silica-filled F-SSBR composites. The C9 resin, C5/C9 resin and SSC could enhance the modulus at 300% and tensile strength of the F-SSBR composite. The four resins could improve the wet skid resistance and wear resistance of the composites. However, Coumarone resin caused poor silica dispersion in the F-SSBR matrix and eventually, the lower modulus, higher loss factor at 60 °C and the higher heat buildup in the composite were comparative to the composite with TDAE. Furthermore, the synergistic effect of the C5/C9 resin and SSC was found to improve the mechanical performance of the composites and it resulted in higher tensile strength and modulus, and a lower heat buildup, compared to the case when only TDAE was used. It is noted that the properties “magic triangle” was broken by the C5/C9 resin and SSC, and the C5/C910T15 increased the wet skid resistance by 21.7%, fuel-saving rate by 2.3%, and wear resistance by 8.3%, while S20T5 increased the wet skid resistance by 30.4%, fuel-saving rate by 7%, and wear resistance by 25% compared with CG.

Dual Function of β-Hydroxy Dithiocinnamic Esters: RAFT Agent and Ligand for Metal Complexation.

The reversible addition-fragmentation chain-transfer (RAFT) process has become a versatile tool for the preparation of defined polymers tolerating a large variety of functional groups. Several dithioesters, trithiocarbonates, xanthates, or dithiocarbamates have been developed as effective chain transfer agents (CTAs), but only a few examples have been reported, where the resulting end groups are directly considered for a secondary use besides controlling the polymerization. Herein, it is demonstrated that β-hydroxy dithiocinnamic esters represent a hitherto overlooked class of materials, which are originally designed for the complexation of transition metals but may as well act as reversible CTAs. Modified with a suitable leaving group (R-group), these vinyl conjugated dithioesters indeed provide reasonable control over the polymerization of acrylates, acrylamides, or styrene via the RAFT process. Kinetic studies reveal linear evolutions of molar mass with conversion, while different substituents on the aromatic unit has only a minor influence. Block extensions prove the livingness of the polymer chains, although extended polymerization times may lead to side reactions. The resulting dithiocinnamic ester end groups are still able to form complexes with platinum, which verifies that the structural integrity of the end group is maintained. These findings open a versatile new route to tailor-made polymer-bound metal complexes.

Effect of Thermal-Oxygen Aging on Temperature Stability of Styrene-Butadiene-Styrene–Modified Asphalt

Abstract In order to explore the effect of aging on the temperature stability of styrene-butadiene-styrene (SBS)-modified asphalt, matrix asphalt and SBS-modified asphalt were used as the control to conduct short-term aging and long-term aging. Three indexes of asphalt with different aging degrees were tested to analyze the change rule of each index. The specific heat capacity and phase transition temperature of SBS-modified asphalt before and after aging were studied by differential scanning calorimetry (DSC). At last, the mechanism was studied by attenuated total reflection Fourier infrared spectroscopy. The results show that the penetration and ductility of matrix asphalt and SBS-modified asphalt decrease with the deepening of aging. The difference is that the softening point of matrix asphalt shows an increasing trend, whereas the softening point of SBS-modified asphalt shows a changing rule of first decreasing and then rising. The addition of SBS modifier can increase the specific heat capacity of asphalt and change the viscosity-flow conversion temperature. The degradation of SBS modifier leads to the decrease of the specific heat capacity after long-term aging, whereas the viscosity-flow conversion temperature decreases first and then rises, which is consistent with the change law of softening point. As a special block copolymer, the specific heat capacity of SBS modifier is determined by the polymer butadiene with lower glass transition temperature, whereas the softening point changes with the polymer styrene with higher glass transition temperature, which is consistent with the change rule of functional group index, softening point, and specific heat capacity of SBS-modified asphalt before and after aging.