Polymerization Of Styrene Research Articles

Nonlinear probabilistic virtual sample generation using Gaussian process latent variable model and fitting for rubber material

The development of material informatics has led to an increasingly deep intersection between material science and machine learning (ML). However, limited data volume significantly hampers the application of machine learning models in materials science. To address this challenge, we propose a virtual sample generation algorithm using Gaussian process (VSG-GP) latent variable model and nonlinear fitting for rubber material. The VSG-GP algorithm is versatile, nonlinear, probabilistic, and interpretable. As we known, we are the first to use the Gaussian process latent variable model (GPLVM) and nonlinear fitting to solve the issue of sample generation in material science. Specifically, GPLVM fits the observed few samples to obtain its low-dimensional representation and latent distribution. Furthermore, if the samples contain labels, we use the Gaussian process regression (GPR) to nonlinearly fit the labels. We consider the polymerized styrene butadiene rubber (SBR) dataset and employ the algorithm to generate virtual samples for the SBR. Our investigation shows that the virtual samples follow the same distribution as the original data. The prediction performances of learning models on the virtual samples indicate the value of the labels generated by GPR. Compared with existing methods, experimental results verify the effectiveness and competitiveness of the proposed algorithm. The accuracies of XGBoost and random forest models on the dataset of original and virtual samples are improved by 39% and 43%, respectively.

Translocation of 14C-polystyrene nanoplastics into fish during a very-low concentration dietary exposure

Assessing the dietary accumulation of nanoplastics in animals following very-low exposure concentrations is restricted due to analytical limitations. This study adapted a method for synthesising semi-stable 14C-PS NPs (through styrene polymerisation) in small volumes for deployment in environmental studies. The method was developed with non-labelled material where the final polystyrene product had a primary particle size of 35 ± 8 nm (as measured by transmission electron microscopy). This method was then applied to 14C-labelled styrene to produce radiolabelled polystyrene nanoplastics (14C-PS NPs). The 14C-PS NPs were added (top-dressed) to a commercially available fish feed, with a measured concentration of 27.9 ± 2.1 kBq kg−1 (n = 5), equating to 5.9 μg polystyrene kg−1 feed. Fish (rainbow trout; Oncorhynchus mykiss) were fed this diet at a ration of 2% body weight per day for a period of two weeks. On day 3, 7 and 14, the fish were sampled for the mid intestine, hind intestine, kidney and liver, and measured for tissue radioactivity (determined by liquid scintillation counting). Some background activity was detected in the control samples (e.g., 1–16 and 4–11 Bq g−1 in the hind intestine and liver, respectively) which is due to natural background fluorescence. By the end of the experiment, the hind intestine and liver had significantly elevated radioactivity (25.3 and 15.0 Bq g−1, respectively) compared to the control, indicating the accumulation of nano polystyrene. In the liver, this equated to 1.8 μg polystyrene g−1 dry weight. This study confirms the accumulation of nano particles in vertebrates at low, environmentally relevant concentration, and highlights radiolabelling as a methodological approach suitable for exploring the bioaccumulation of nanoplastics and potential impacts.

Effect of cationic surfactant tail length on the emulsion gel polymerization of styrene

Effect of cationic surfactant tail length on the emulsion gel polymerization of styrene

Selective laser sintering of acrylonitrile butadiene styrene polymer and post-processing enhancement: an experimental study

Selective laser sintering of acrylonitrile butadiene styrene polymer and post-processing enhancement: an experimental study

Combating toxic emissions from thermal recycling of polymeric fractions laden with novel brominated flame retardants (NBFRs) in e-waste: an in-situ approach using Ca(OH)2.

Legacy brominated flame retardants (BFRs) in printed circuit boards are gradually being replaced by novel BFRs (NBFRs). Safe disposal and recycling of polymeric constituents in the polymeric fractions of e-waste necessitate the removal of their toxic and corrosive bromine content. This is currently acquired through thermal recycling operations involving the pyrolysis of BFRs-containing materials with metal oxides. Nonetheless, the debromination capacity toward NBFRs is yet to be established. Thus, this study aims to address these two crucial gaps in the current knowledge pertaining to the plausible formation of brominated toxicants from the thermal decomposition of NBFRs and their thermal recycling potential. Herein, we investigate the pyrolysis of a mixture of 2,4,6-tribromophenol (TBP), allyl 2,4,6-tribromophenyl ether (ATE) and Tetrabromobisphenol A-bis (2,3-dibromo propyl ether) (TBBPA-DBPE) in the presence of acrylonitrile butadiene styrene (ABS) polymers at various loads. To demonstrate a viable debromination route, pyrolysis of NBFRs-ABS mixture with Ca(OH)2 was also investigated. The latter is a potent debromination agent for legacy BFRs. Upon pyrolysis with Ca(OH)2, the bromine content in the collected oil was reduced up to 80.49% between 25-500 °C. Products of the co-pyrolysis process generally feature non-brominated aromatic and aliphatic compounds; a finding that indicates an effective thermal recycling approach. As evident by IC measurements, no HBr emission could be detected when Ca(OH)2 is added to the mixture. As XRD patterns show, Ca(OH)2 is partially converted into CaBr2. DFT calculations provide pathways for the observed surface debromination characterized by surface-assisted fission of aromatic C-Br bonds and the formation of CaBr sites. Outcomes reported herein are instrumental to designing and operating a thermal recycling facility of polymeric materials contaminated with high loads of bromine, i.e., most notably during scenarios encountered in the thermal recycling of e-waste.

Thermal and thermomechanical properties of boron nitride-filled acrylonitrile butadiene styrene (ABS) composites

The present study aims at investigating the effect of hexagonal boron nitride (hBN) nanoplatelets on the properties of acrylonitrile butadiene styrene (ABS) polymer. Composites containing 0-30 vol% hBN were prepared through batchwise melt compounding, which was followed by compression molding. Subsequently, the thermal and thermomechanical properties of the fabricated samples were investigated. The dynamic mechanical analysis (DMA) revealed that the storage modulus of the samples was markedly improved in the entire examined temperature range, while the glass transition temperature also gradually increased as a function of hBN content. According to the thermogravimetric analysis (TGA), the incorporated boron nitride particles enhanced the thermal stability of ABS composites, exhibiting a notably higher decomposition onset temperature. Additionally, the thermal conductivity of the ABS/hBN composites significantly increased by 570% when the hBN content was 30 vol%.

Nonporous Graphene‐Oxide Coated by Acrylonitrile Polystyrene as New Adsorbent in Dispersed Solid Phase Microextraction for Estimating Pesticides in Aqueous Samples

AbstractGraphene oxide (GO) – acrylonitrile polystyrene (APS) copolymer nanoparticles was synthesized and used for preconcentration and determination of triazole pesticides in an aqueous sample by dispersed solid phase microextraction (DSPME). Graphene oxide was produced using the Hummers method and then coated with acrylonitrile styrene polymer. The synthesized adsorbent was characterized by FT‐IR, XRD, and FE‐SEM analysis. The influence of the effective parameters on the DSPME process was investigated. The results showed that the highest extraction efficiency was obtained by methanol as a desorption solvent, in pH 6, with 20 mg of adsorbent at 20 minutes. At optimum conditions, penconazole, hexaconazole, diniconazole, triticonazole, difenoconazole, tebuconazole were determined by DSPME with GO‐ASP adsorbent in water sample. The linearity ranges were from 10 to 10000 ng ml−1 and the detection limits were varied from 0.31–0.34 ng ml−1. This method was used for estimating triazole pesticides in a river water sample.

Synthesis of rGO-Fe3O4 and La4BaCu5O13.10 and their polymer composites for electromagnetic interference shielding applications

This article reports polymer-based composites and their shielding effectiveness in X-band frequency. We synthesized rGO-Fe3O4 and La4BaCu5O13.10 using one-pot hydrothermal and nitrate citrate gel method respectively. Their phase purity and structural, functional, and morphological characterization are confirmed with PXRD, FTIR, and SEM characterization techniques. The shielding effectiveness (SE) and their mechanism were studied by incorporating synthesized nanomaterials with multiwall carbon nanotube (MWCNT) in an acrylonitrile butadiene styrene (ABS) polymer matrix with a uniform thickness of 1 mm. rGO-Fe3O4 along with MWCNT in the ABS matrix, shows a total shielding efficiency (SET) of 26 dB with a percentage of absorption of 70 %, in comparison to La4BaCu5O13.10 with MWCNT in the ABS matrix shows SET 24 dB with absorption percentage 80 %. The SET of the two composites is comparable, but their mechanism of shielding EM waves differs considerably. Understanding the shielding mechanism allows one to choose fillers with magnetic, dielectric, or metallic properties for different EM applications. It also provides insight into designing shielding materials to achieve maximum shielding ability by blending different filler materials.

U.S. plastic waste exports: A state-by-state analysis pre- and post-China import ban

This study analyzes the regional implications of China's 2017 import ban on plastic waste by examining U.S. census data. A statistically significant decrease in total U.S. plastic waste exports was found, dropping from about 1.4 million tons to 0.6 million tons in the post-ban period. California remained the top exporter, throughout both pre- and post-ban periods, while South Carolina exhibited the highest per capita exports. Malaysia emerged as the largest importer of U.S. plastic waste, followed by Vietnam, Indonesia, and Thailand. The ban also led to a change in the composition of the exported plastic waste. Ethylene polymers increased from 32.6% of total exports in the pre-ban period to 46.9% in the post-ban period. Other plastics (vinyl chloride polymers, styrene polymers, and for plastics not elsewhere specified or included) decreased from 67.4% of total exports in the pre-ban period to 53.1% in the post-ban period. Moreover, we found that exporting plastic waste has significant environmental and human health impacts. For example, the Global Warming Potential (GWP) decreased from 20 million tons CO2-eq in the scenario where 100% of plastics are exported, or 25 million tons exported from the U.S. since 2002, to −11.1 million tons CO2-eq in the scenario where 100% of plastics are treated domestically. Transportation exacerbates these impacts for exported waste scenarios, increasing to 5.4 million tons CO2-eq when plastics are exported by ship while decreasing to 0.9 million tons CO2-eq for domestic treatment. Although exporting plastic waste is initially cost-effective, our study highlights that investing in domestic waste management can yield significant long-term benefits, considering the environmental and public health impacts. Therefore, it is crucial to prioritize context-specific solutions to address the challenges of the evolving global plastic waste landscape.

Transfer Learning of Full Molecular Weight Distributions via High-Throughput Computer-Controlled Polymerization.

The skew and shape of the molecular weight distribution (MWD) of polymers have a significant impact on polymer physical properties. Standard summary metrics statistically derived from the MWD only provide an incomplete picture of the polymer MWD. Machine learning (ML) methods coupled with high-throughput experimentation (HTE) could potentially allow for the prediction of the entire polymer MWD without information loss. In our work, we demonstrate a computer-controlled HTE platform that is able to run up to 8 unique variable conditions in parallel for the free radical polymerization of styrene. The segmented-flow HTE system was equipped with an inline Raman spectrometer and offline size exclusion chromatography (SEC) to obtain time-dependent conversion and MWD, respectively. Using ML forward models, we first predict monomer conversion, intrinsically learning varying polymerization kinetics that change for each experimental condition. In addition, we predict entire MWDs including the skew and shape as well as SHAP analysis to interpret the dependence on reagent concentrations and reaction time. We then used a transfer learning approach to use the data from our high-throughput flow reactor to predict batch polymerization MWDs with only three additional data points. Overall, we demonstrate that the combination of HTE and ML provides a high level of predictive accuracy in determining polymerization outcomes. Transfer learning can allow exploration outside existing parameter spaces efficiently, providing polymer chemists with the ability to target the synthesis of polymers with desired properties.

In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

This study presents a nitrogen-doped microporous carbon nanospheres (N@MCNs) prepared by a facile polymerization–carbonization process using low-cost styrene. The N element in situ introduces polystyrene (PS) nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent, and then carbonization obtains N@MCNs. The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride. The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure. The results showed that N@MCNs exhibit superb reduction performance of friction and wear. When the addition of N@MCNs was 0.06 wt%, the friction coefficient of PAO-10 decreased from 0.188 to 0.105, and the wear volume reduced by 94.4%. The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%, respectively. The carrying capacity of load was rocketed from 100 to 400 N concurrently. Through the analysis of the lubrication mechanism, the result manifested that the prepared N@MCNs enter clearance of the friction pair, transform the sliding friction into the mixed friction of sliding and rolling, and repair the contact surface through the repair effect. Furthermore, the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides, which can avert direct contact with the matrix and improve the tribological properties. This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction. This preparing method can be ulteriorly expanded to multi-element co-permeable materials. Nitrogen and boron co-doped carbon nanospheres (B,N@MCNs) were prepared by mixed carbonization of N-enriched PS and boric acid, and exhibited high load carrying capacity and good tribological properties.

Investigation of poly (styrene-4-vinylbenzyl chloride) as a curing agent for alternative plant proteins

ABSTRACT Poly (styrene-4-vinylbenzyl chloride) (PSVBC) was synthesized by polymerization of 4-vinylbenzyl chloride and styrene. FTIR was used for characterization of PSVBC and for curing of three protein/PSVBC adhesives (proteins include potato, corn, and pea proteins). Protein-PSVBC adhesives were investigated for bonding maple veneers. The shear strength and water resistance of the resultant maple laminates were evaluated. More specifically, the effects of the NaOH concentration, hot press conditions (temperature and time), total solids content, and protein-PSVBC weight ratios on the shear strengths and water resistance were studied. The addition of PSVBC improved the wet shear strength of the laminates from 0.1 to 0.85 MPa for potato-PSVBC adhesive and from 0.1 to 0.73 MPa for corn-PSVBC adhesive. However, the addition of PSVBC did not increase the wet strength of the laminates for the pea-PSVBC adhesive.

Half-Sandwich Rare-Earth metal complexes bearing 4,5,6,7-Tetrahydroindenyl ligands for highly Syndiospecific (Co)Polymerization of styrene

As Cp-derived ligands, substituted 4,5,6,7-tetrahydroindene (THI) ligands with tunable steric bulk have been synthesized, and their ligated half-sandwich rare-earth metal complexes were also sucessfully prepared and tested for styrene (co)polymerization. In conjunction with [Ph3C][B(C6F5)4], the THI-ligated scandium complexes exhibited high catalytic activity for highly syndiotactic polymerization of styrene (>99% rrrr). THI3Me-Sc/[Ph3C][B(C6F5)4] binary system also promoted the copolymerization of styrene and isoprene/butadiene by both the concurrent addition and sequentical addition of monomers, affording the copolymers with block microstructure as deterimined by NMR (1H and 13C) spectra. The huge difference in reactivity ratios betewen styrene and isoprene/butadiene (rIP / rSt = 31.1 and rBD / rSt = 173.6) revealed in kinetics investigation further proved the predominantly block structure of resultant copolymers.

Thermal and Dielectric Investigations of Polystyrene Nanoparticles as a Viable Platform-Toward the Next Generation of Fillers for Nanocomposites.

Nanoparticles are often used as fillers for enhancing various properties of polymer composites such as mechanical, electrical, or dielectric. Among them, polymer nanoparticles are considered ideal contenders because of their compatibility with a polymer matrix. For this reason, it is important that they are synthesized in a surfactant-free form, to obtain predictable surface and structural properties. Here, we synthesized a series of polystyrene nanoparticles (PS NPs), by emulsion polymerization of styrene, using varying amounts of divinylbenzene as a crosslinking agent and sodium 4-vinylbenzenesulfonate as a copolymerizing monomer surfactant-"surfmer". Using "surfmers" we obtained surfactant-free nanoparticles that are monodisperse, with a high degree of thermal stability, as observed by scanning electron microscopy and thermogravimetric investigations. The prepared series of NPs were investigated by means of broadband dielectric spectroscopy and we demonstrate that by fine-tuning their chemical composition, fine changes in their dielectric and thermal properties are obtained. Further, we demonstrate that the physical transformations in the nanoparticles, such as the glass transition, can be predicted by performing the first derivative of dielectric permittivity for all investigated samples. The glass transition temperature of PS NPs appears to be inversely correlated with the dielectric permittivity and the average diameter of NPs.

Facile access to redox responsive self-healing coating materials via living cationic block copolymerization of styrene and 2-chloroethyl vinyl ether

Poly(alkyl vinyl ether)-based functional copolymers have wide applications in many high-tech areas. However, their synthesis is still challenging which limits their applications. This article describes the synthesis of an unprecedented redox-responsive polystyrene-block-poly(2-thioethyl vinyl ether) (PSt-b-PTEVE) diblock copolymers via sequential “water tolerant” cationic polymerization of St and CEVE, followed by post-polymerization transformation of the pendant -CH2CH2Cl functionalities of PCEVE segment to -CH2CH2SH functionalities. The initiating system enabled controlled cationic polymerization of styrene (St), yielding well-defined PSt (at least up to 22500 g/mol) with relatively low dispersity (Đ ≤ 1.36) and polystyrene-block-poly(2-chloroethyl vinyl ether) (PSt-b-PCEVE) diblock copolymers with acceptable dispersity values (Đ ≤ 1.38) thereof, demonstrating high chain-end fidelity. The controlled character of the cationic polymerization reaction was confirmed by linear kinetic plots, linear increase of Mns (with low Đs) and synthesis of PSts of changing Mns simply by varying initial [St]0/[Initiator]0 feed ratio. The synthesized PSt-b-PTEVE diblock copolymers exhibited redox responsivity and self-healing behaviour. The self-healing property of the PSt-b-PTEVE diblock copolymer was studied by optical microscopy. For this, first, a mechanical cut was introduced in the cross-linked PSt-b-PTEVE thin films and then images were taken at regular intervals to investigate the healing. These promising PSt-b-PTEVE diblock copolymers might have potential applications in many emerging areas, including functional coating.

The mechanical properties of polystyrene composites were improved by designing large‐size 3D GO/CNTs hybrid aerogel reinforced by epoxy resin

AbstractDispersion of carbon nanomaterials in polymers has long been a challenge. In this work, large‐scale epoxy‐reinforced GO/CNT aerogel (GECA) was prepared with stable three‐dimensional (3D) interconnected network as reinforced skeleton. The GECA/polystyrene (GECA/PS) nanocomposites were then fabricated by in‐situ polymerization of styrene in interconnected GECA. The results showed that the obtained GECA exhibited high compression modulus with no significant permanent deformation. Furthermore, the mechanical properties of the prepared GECA/PS were significantly improved with a low filler content of 1.0 wt.%. when the ratio of GO and CNT to epoxy resin was 1:1, the tensile strength, flexural strength, compressive strength, and impact strength of the composites were the highest, at 17.51 MPa, 33.01 MPa, 110.28 MPa, and 4.169 KJ/m2, respectively, representing an increase of 113.0%, 76.1%, 147.5%, and 99.5%, respectively.

Effect of the catalyst type on pyrolysis products distribution of polymer blends simulating plastics contained in waste electric and electronic equipment

The valorization of the plastic part from waste electric and electronic equipment (WEEE) is of significant importance for the upcycling of this waste stream with pyrolysis proposed as an appropriate, environmentally friendly, thermo-chemical recycling technique. The subject of this study is to investigate the distribution of the products obtained after the addition of certain catalysts in the pyrolysis of polymer blends with a composition similar to that of plastics in WEEE. Specifically, blends of acrylonitrile-butadiene-styrene (ABS), high impact polystyrene (HIPS), polycarbonate (PC), polypropylene (PP) and poly(vinyl chloride) (PVC) were examined in experiments taking place in a lab scale pyrolyser coupled with gas chromatography/mass spectrometry (Py-GC/MS) for the on-line recording of the products obtained. Six different catalysts (CaO, γ-Al2O3, Fe2O3, ZSM-5, Silicalite, Al-MCM41) were used and the optimum pyrolysis temperatures were selected for each system based on evolved gas analysis. The results from catalytic cracking were compared and evaluated in terms of the number of compounds produced, the ratio between aromatic and aliphatic products, and the intensity of the peaks. It was found that the best choice for the decomposition of ABS is Fe2O3 and for HIPS the Al-MCM41. γ-Al2O3 affects PC degradation and CaO exhibits specific selectivity to this polymer. Pyrolysis of blends results in the production of a mixture of hydrocarbons together with other aliphatic and aromatic compounds. Polymer blends including chlorinated compounds such as PVC start degrading at relatively low temperatures, slightly over 200 °C. Degradation occurs in two steps with peaks around 300 and 465 °C, respectively. The first is attributed to the removal of halogenated compounds and the second to the scission of the main carbon chain. PVC degradation produces chlorine radicals that affect the degradation mechanism. The presence of the catalysts did not significantly change the temperatures of degradation. However, they do change the type of the products obtained. Pyrolysis of the styrenic polymers, i.e. ABS or HIPS resulted in mainly aromatic compounds with one, two or even three aromatic rings, whereas PC results in several phenols. CaO is proposed as the best choice for catalytic cracking of Blend A, whereas Silicalite should be considered for Blend B since it leads in the production of more aromatic compounds compared to conventional pyrolysis.

Superacid-Assisted Degradation of Polystyrene

We report the degradation pathway of polystyrene in a low-temperature environment by superacid. Polystyrene is a thermoplastic resin widely used in packaging, disposable products, and structural materials. However, economically viable upcycling of polystyrene has yet to be established because of the high cost of chemical recycling and the low value of products. To understand the degradation pathway of polystyrene and establish competitive upcycling practices, we investigated the transformation of normal and deuterated polystyrene chains into small compounds by triflic acid at 20 °C. The degradation study of deuterated polystyrene showed the high stability of the hydrogens at the α carbons of polymerized styrene against triflic acid, which suggests the known β-scission degradation pathway of polystyrene by α-proton abstraction is unlikely. Rather, the polystyrene degradation proceeds through three distinct stages: (i) intrachain cross-linking that forms polymer nanoparticles and simultaneous transformation of polymerized styrene to indan units, (ii) degradation of the polymer nanoparticles into small molecular weight compounds, and (iii) formation of polycyclic aromatic hydrocarbons. The stepwise degradation pathway of polystyrene we report may enable the design of efficient and profitable upcycling processes for end-of-life polystyrene products in low-temperature environments.

Morphological and Mechanical Characterization of Friction Stir Welded Zones in Acrylonitrile Butadiene Styrene (ABS) Polymer

Morphological and Mechanical Characterization of Friction Stir Welded Zones in Acrylonitrile Butadiene Styrene (ABS) Polymer

Structured nonlinear process modeling using neural networks and application to economic optimization

This paper presents a model identification approach to develop structured dynamic models that utilize both the available first principles knowledge and neural networks (NNs) estimated from data. The NNs in the dynamic model are used to approximate some complex unknown functions that may be challenging to model in applications using the available first principles knowledge. The parameters in the NNs are estimated by solving a multistep ahead prediction error minimization problem. The efficacy of the modeling approach is demonstrated via case studies with an illustrative chemical reactor and an industrially relevant styrene polymerization process. In the latter example, we use NNs to approximate unknown reaction kinetics and polymer moment functions in the structured model. The economic performances of the structured models are analyzed by solving a steady-state optimization problem. First, we elucidate that to obtain a good steady-state economic performance using the structured models, the training data collected from the plant should contain sufficient steady-state information. In the styrene polymerization example, we examine the economic performances of two structured models with different NN parameterization choices. We show that a structured model that utilizes the most possible physical information about the process provides a median loss of 6.4% compared to the optimal performance of the true plant across a range of steady-state problems. We emphasize in the case studies that physical insight about the process is critical to obtain good economic performance using the structured models.