Styrene Concentration Research Articles

Influence of binary waste mixtures on road performance of asphalt and asphalt mixture

The utilization of processed waste materials in road construction is of utmost significance from the environmental and economic viewpoints. In this paper, waste cooking oil (WCO) and ground tire rubber (GTR) were applied to modify the asphalt binder. Based on the optimal content of both modifiers, sixteen asphalt samples with different combinations of the two wastes were designed. Relevant tests including basic properties along with rheological behavior and chemical characterization were carried out on the modified asphalt. The results indicated that the modified asphalt with 20 wt % GTR and 2.5 wt %-5 wt. % WCO exhibited satisfactory high temperature resistance and low temperature rheological properties. The Fourier transform infrared spectroscopic investigation revealed that the presence of GTR increased the concentration of styrene and butadiene while the addition of WCO introduced fatty acids and esters to modified asphalt. Overall, the road performance studies demonstrate that modified asphalt mixture with 5 wt % WCO and 20 wt % GTR displayed a markedly improved anti-rutting properties, water stability and superior low-temperature performance compared to normal asphalt mixture.

Evaluation of health risks associated with exposure to volatile organic compounds from household fuel combustion in southern India

Volatile organic compounds (VOCs) from household cook-fuel use are a major public health concern in low and middle income countries (LMICs), but health risk assessments have largely been based on measurements of fine particulate matter. We report results from cooking period measurements of 21 non-methane VOCs (NMVOCs) and estimated lifetime cancer risk for women cooks in the Tamil Nadu Air Pollution and Health Effects (TAPHE) cohort in Southern India. We enrolled 112 (56 biomass, 23 kerosene and 33 liquefied petroleum gas (LPG) using) TAPHE households to perform kitchen area measurements during the cooking period. VOC samples were collected on mixed-bed sorbent thermal desorption tubes using low-volume air samplers and analyzed using automated thermal desorption on a GC-MS system. Pentafluorobenzene, 1,4-difluorobenzene and chlorobenzene-d5 were used as internal standards that provided recoveries ranging from 81.7% to 119.9%. Total VOC concentrations were 4617 µg/m3, 2839 µg/m3 and 1639 µg/m3 while total BTEXS (i.e. benzene, toluene, ethylbenzene, m,p-xylene, o-xylene and styrene) concentrations were 139 µg/m3,121 µg/m3 and 245 µg/m3 among biomass, LPG and kerosene using households, respectively. Sampling season, type of food cooked and kitchen ventilation were significantly associated with measured total NMVOC concentrations. Lifetime cancer risks were estimated to be 2.93 × 10−3, 1.55 × 10−4 and 8.18 × 10−5, for biomass, kerosene and LPG fuel users, respectively with 1,2,3-trichloropropane, benzene, 1,4-dichlorobenze, 1,2-dibromoethane and chloroform contributing maximally to excess cancer risks. Health risk assessments for women cooks in LMICs should be expanded to include NMVOCs as these risks may not be adequately addressed through measurements of fine particulate matter (PM2.5) pollution alone.

Thermo-Chemical Treatment for Carcass Disposal and the Application of Treated Carcass as Compost

A mechanized thermo-chemical treatment system was developed to treat the undecomposed carcass and remediate livestock burial sites. Animal carcasses were thus processed via crushing, mixing, and treatment with quicklime treatment, heat treatment (200–500 °C), and mixing with sawdust. The machinery was applied to two sites where 16,000 chickens and 418 pigs had previously been buried in fiber-reinforced plastic storage bins. No dioxins were detected in the gas discharged during processing, and the concentration of total volatile organic compound, toluene, ethylbenzene, xylene, and styrene were 430.3, 139.0, 18.3, 21.4, and 10.4 μg/m3, respectively, which were below the air pollutant emission standards issued by the Korean Ministry of Environment. Korean standards stipulating the use of treated carcasses as compost (C, N, and P content, heavy metal concentration, Escherichia coli, and Salmonella) were met, but the germination index value was less than 70, not satisfying the criteria. Plant height, leaf length, leaf width, and dry weight of lettuce grown in soil amended with treated carcass product were significantly lower than those grown in low nutrient soil due to the poor germination index of the treated carcass. These results indicate that a composting process is required before the use of the treated carcass as a fertilizer. The addition of zeolite retarded the elution of ammonia from the carcasses and its efficiency was about 87.9%. It is expected that the mechanized thermo-chemical treatment process developed in this study could replace other technologies for the remediation of livestock burial sites.

Poly 4-Vinylpyridine and Polystyrene Based Interpenetrating Polymer Networks (IPNs): Synthesis and Characterization

A study on synthesis of thin film of interpenetrating polymer network (IPN), of poly(4-vinylpyridine) (PVP) and polystyrene was carried out. A series of IPN was synthesized, using divinyl benzene (as cross linker) and benzoyl peroxide (as an initiator) and characterized using FT-IR spectroscopy, scanning electron microscopy (SEM), thermal (DSC, TGA) and fluorescent techniques. FTIR spectra revealed the presence of PVP at 1584 cm–1 and polystyrene at 1609 cm–1. Shifting in band positions depicts formation of IPN. SEM images show a clear dual phase morphology. DSC thermogram reveals glass transition temperature (Tg) value of the polymer network at 350 ºC. TGA graph depicts thermal stability of IPN upto 400 °C. The XRD pattern of IPN indicates semi crystalline nature. The properties such as average molecular weight between crosslinks (Mc), percentage swelling is found to be the direct function of initiator (BPO) and inverse function of concentration of cross linker (DVB) and styrene. Fluorescence spectra of IPN observed in visual range of 506 nm.

High Solids Hydroxy‐TEMPO Mediated Radical Semibatch Emulsion Polymerization of Styrene

AbstractStable polystyrene latexes having controlled molecular weight distribution (MWD) with solids contents up to 40 wt% are obtained using potassium persulfate as initiator with the nitroxides 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (hydroxy‐TEMPO) and 4‐amino‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (amino‐TEMPO). Using different concentrations of styrene (St) in the nucleation step, it is possible to create colloidal dispersions with particle size ranging from ≈57 to ≈390 nm, conversions up to ≈96%, nitroxide efficiencies (NEff) up to ≈0.76, and number average molecular weight (Mn) ranging from ≈10 000 to ≈85 000 g mol−1. The effect of the monomer feed rate in the semibatch step is also studied. These polymerizations do not require a separate macroinitiator synthesis, since this is formed in situ during the heating ramp. A mathematical model is used to compare the mechanistic understanding of the system with the experimental results.

Effect of polystyrene and silica compositions on formation of raspberry-like hollow nanoparticles: synthesis strategy and morphological study

Raspberry-like hollow hybrid nanoparticles were facilely prepared via simultaneous miniemulsion sol–gel reaction/free radical polymerization of tetraethyl orthosilicate, 3-methacryloxypropyl trimethoxysilane (MEMO) and styrene (ST). MEMO played an important role in controlling their morphologies from dense silica nanoparticles to raspberry-like and raspberry-like hollow hybrid nanoparticles. The hybrid nanoparticles were obtained from the miniemulsion reaction technique with 2 wt% MEMO with or without ST exhibit raspberry-like hollow nanoparticles. The corresponding number-average diameter of hybrid nanoparticles increased from 112 to 126 nm as the ST concentration increased from 0 to 5 wt%. The (raspberry-like hollow) porous silica particle sizes after calcination are 47, 76, 78 and 85 nm for the runs with 0, 1, 2 and 5 wt% ST, respectively. Moreover, for constant level of MEMO at 2 wt%, the highest specific surface area (800 m2 g–1) was achieved for the runs with the ST concentration = 0–1 wt%. Then, it steadily decreased from ca. 710 to 510 m2 g–1 when the ST concentration increased from 1.5 to 20 wt%. As for constant level of ST at 0.5 wt%, the specific surface area is ca. 626, 797 and 580 m2 g–1 for the runs with 1, 2 and 3 wt% of MEMO, respectively.

Emission fluxes of styrene monomers and other chemicals for products containing expanded polystyrene beads.

Styrene in indoor air can adversely affect human health. In this study, styrene monomer and other chemical emission fluxes for products containing expanded polystyrene beads (pillows, cushions, and soft toys) were measured at various temperatures to simulate typical product use. The contributions of the products to styrene and other chemical concentrations in indoor air and human exposure to these chemicals were estimated, and health risk assessments were performed. The styrene monomer emission fluxes for the samples at 25°C were between 25.3 and 8.73×103 μg/(m2 h). The styrene emission fluxes for the product surfaces increased strongly as the temperature increased, from between 124 and 2.44×104 μg/(m2 h) at 36°C (simulating human body temperature) to between 474 and 4.59×104 μg/(m2 h) at 50°C (simulating inside an automobile in summer). The hexane, heptane, toluene, octane, ethylbenzene, m- and p-xylene, o-xylene, and dodecane emission fluxes at 25°C for the sample that emitted the analytes most readily were high. The maximum estimated styrene and xylene concentrations in indoor air caused by emissions from expanded polystyrene beads at 36°C in a bedroom and automobile were higher than the relevant guidelines. The maximum contribution of a product containing expanded polystyrene beads in a living room, bedroom, or automobile could cause the total volatile organic compound concentration in air to exceed the advisable value (400 μg/m3). The estimated maximum hazard quotients for styrene, toluene, and xylene emitted by a product containing expanded polystyrene beads at 36°C in a bedroom were 0.59, 0.30, and 0.37, respectively. These non-carcinogenic risk values for single products could contribute to the non-carcinogenic risk thresholds being exceeded when multiple products and other sources of chemicals are taken into consideration. The estimated styrene concentrations suggest that products containing expanded polystyrene beads are important sources of styrene to indoor air.

Improving glass transition temperature of unsaturated polyester thermosets: Conventional unsaturated polyester resins

AbstractHighly crosslinkable unsaturated polyester resins (UPR) have attracted many interests in the application as reinforced matrix materials. Here, we present a systematical study of the influence of different curing conditions and styrene concentrations on resin viscosity and dynamic‐mechanical properties of the thermoset. The pure maleic Palapreg® P18‐03 was selected as model UPR because of its broad industrial use. By applying newly developed thermal curing profiles (without thermal initiators) and by raising the styrene content, the Tg of the network could be increased up to 206/215°C (1/10 Hz). For the first time, a fast curable UPR based on propylene glycol and neopentyl glycol with a Tg of up to 215°C is described. A partial substitution of problematic styrene with methylmethacrylate, tert‐butylacrylate, and maleic anhydride (MA) was studied as well. MA leads to significantly improved resin reactivity. A resin containing 42 wt% styrene and 8 wt% MA yields thermosets with remarkably improved mechanical properties and with a narrower glass transition range compared to the original P18‐03.

Occurrence of Emerging Pollutants in Skudai River in Johor Bahru Region of Malaysia

Increase in landuse development and human activities have significant influence on the occurrence of emerging pollutants (EPs) in water bodies such as rivers. As rivers are the main source of water supply in Malaysia, a study was conducted to determine the occurrence of EPs in one of the drinking water sources, namely Skudai River. Samples were collected five times at eight sampling points from the upstream up to the water intake of the river. Sample pre-treatment was performed by solid-phase extraction (SPE), whereas the analyses of the EPs were performed by Liquid Chromatography-Mass Spectrometry (LCMS-MS QTOF). Results showed that about 50 compounds were detected and fall into categorise as pharmaceuticals, Personal Care Products (PCPs), and Endocrine Disrupting Chemical (EDC). The most prevalent (75-100%) compounds detected were of these categories, whereas the least (less than 40%) were mainly pharmaceuticals. The concentration of styrene, a health-hazards EPs ranged from 45.11 to 203.48 µg/L with increasing trend towards downstream of the river. Based on the landuse data of Skudai River Basin, the study concluded that human activity, landuse, and environmental factors could possibly contribute to the presence of the EPs in the river.

A study on benzene release during water washing of biomass

AbstractWater washing can effectively remove Na, K, and Cl in biomass, which can cause fouling, slagging, and corrosion during thermal conversion process of biomass fuels. However, it is necessary to dispose the leachates appropriately after water washing. Characterization of organic matters in leachates should be performed first, which is beneficial to find an effective way to dispose the leachate. In this study, four biomass materials are washed with the deionized water at 30°C, 60°C, and 90°C. The release of toluene and styrene is studied. The results show that yields of organic matters for corn stalk and wheat straw are the highest relatively, of which the eventual values are 8% and 15%, respectively. Less toluene and styrene are released at 30–60°C than that at 90°C for wheat straw. But the release of toluene and styrene in rice hull leachate shows the opposite trend. The concentration of styrene in leachates reaches a minimum value at 60°C. The corresponding values are 0.017 mg L−1 for wheat straw and 0.15 mg L−1 for rice hull. But none is detected in corn stalk and sorghum stalk leachates. In addition, variations of toluene and styrene concentrations are obviously different with different washing temperatures.

Styrene Monomer Migration from Expanded Polystyrene Into Food Acids and Ethanol

Migration of styrene monomer from expanded polystyrene (EPS) at various time intervals (3 hr, 1, 2, 3, 5, 7, 9, 12, 18 days at 51OC) into nine different stimulants (water, 8% ethanol in water, 3% acetic acid, and 3 and 10% of food-grade citric, malic and tartaric acid) was determined using a modified FDA migration cell. Exposure to 8% ethanol resulted in the greatest average migration of styrene (147.6 µg/L) during 18 days of storage compared to all other stimulants tested. The concentration for styrene in 8% ethanol ranged from 49.3 to 228.5 µg/L over all exposure times. For all stimulants tested, styrene concentrations were greater than or equal to 22 µg/L after 3 hours of exposure. EPS exposed to malic (3 and 10%) and 10% tartaric acids had greater styrene migration than styrene exposed to all other acidic stimulants tested.

BTEXS Concentrations and Exposure Assessment in a Fire Station

The aim of this study was to evaluate benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) concentrations in the changing room and garage in a fire station located in the Upper Silesian agglomeration (Poland), to compare them with the concentrations of the same compounds in the atmospheric air (outdoor background) and to assess the health exposure to BTEXS among firefighters and office workers in this unit. BTEXS samples were collected during the winter of 2018 in parallel in the garage, in the changing room, and outside, using sorption tubes filled with activated carbon. The average total BTEXS concentrations in the changing room and garage were over six times higher than those in the atmospheric air in the vicinity of the fire station. At each sampling site, toluene and benzene had the highest concentrations. According to the diagnostic indicators, the combustion of various materials and fuels was the source of BTEXS inside, while outside, the sources were the combustion of fuels and industrial activity. The carcinogenic risk related to benzene inhalation by the firefighters and office employees in the monitored unit exceeded the acceptable risk level value of 7.8 × 10−6 per 1 μg/m3 by more than 20 times.

Styrene Detection in Water By Polythiophene Nanoparticles Suspension

Introduction The versatility of fluorescent reporters makes them adaptable to the detection of different chemicals. [1] Most fluorescent systems work in quenching mode, namely the sensor signal consists in a reduction of the emission; less frequent is the case of sensing molecules where the fluorescence is activated by the interaction. Recently, this behavior has been demonstrated in optical fluorescent reporters made of Poly(3-octylthiophene) nanoparticles have been recently reported. [2] In this work we utilized a similar approach to detect styrene in water. Styrene is an aromatic hydrocarbon, used for the preparation of polystyrene, one of the most popular polymers, widely used in many industrial processes. Here we investigated the feasibility of Poly[3-(Ethyl-6-hexanoate)thiophene-2,5-diyl], hereinafter referred to as either polythiophene or PT, nanoparticles stabilized in aqueous medium by the presence of poly-vinyl alcohol (PVA). Actually, these nanoparticles are able to sense the presence of styrene by increasing the fluorescence emission. The sensor is enough sensitive to detect the styrene dissolved in water solution from the gaseous phase. Thus, this system can be used to measure not only styrene contamination in water, but also styrene contamination in air. This latter event threats the health of workers in several industrial processes.Saturated styrene vapors were mixed with nitrogen by mass flow controllers and then fluxed over the water solutions, obtaining different concentrations of styrene in the liquid phase (following the Henry’s law). This latter case enables to reach low concentrations in water. Results shows a high sensitivity to styrene. The selectivity has been tested comparing the response to an alcohol (ethanol) and a chlorinated solvent (chloroform). Experimental Synthesis of nanoparticles was performed using typical procedure for polythiophene nanosystems [2]; 100 mL of PT solution in THF (10 mg/ mL) was added to 1 mL 1 % w/w PVA on a stirrer. The THF evaporation within 5 min was resulting in nanoparticle formation. TEM images of PT nanoparticles are reported in Figure 1.Figure 2 shows the characterization setup. Styrene saturated vapors were diluted with nitrogen gas to achieve a desired concentration and fluxed in the headspace of PT suspended in water. Saturated vapor pressures were calculated by Antoine equation, whereas air-water coefficient partition was used to calculated the concentration in water due to the solubilization. Fluorescence changes were recorded by Shimadzu RF-1501 fluorimeter. Results Figure 3 shows the emission spectra of PT nanoparticles in water excited at 490 nm. Styrene in water elicits the increase of emission. A peak at 585 nm in the emission spectra is observed under styrene exposure. At concentrations in air above 40 ppm, a second peak at 620 nm is observed. The intensity at 585 nm is barely linear with the concentration in air (Figure 4). Due to the emergence of the additional peak at 620 nm, the peak at 585 becomes broader, and this behavior affects the linearity of the sensor response. A proper multicomponent analysis of spectral data provides a better estimation of the styrene concentration. The linear fit of Figure 4 returns a sensitivity of about 3 ppm-1 respect to styrene in air. The sensitivity has also been measured respect to an alcohol (ethanol) and a chlorinated solvent (chloroform). Figure 5 shows that sensitivity to styrene is about an order of magnitude larger respect to chloroform and three orders of magnitude respect to ethanol. Acknowledgements. “Financial support from Italy-Poland Canaletto program, project PO19MO08 is gratefully acknowledged.”

Synthesis and thermal curing of liquid unsaturated polysilsesquioxane and its mechanical and thermal properties

The liquid unsaturated polyhedral oligomeric silsesquioxane (PMPOSS) has been successfully synthesized via the hydrolysis-condensation reaction of phenyltrimethoxysilane (PTMS) and methacryloxypropyl trimethoxysilane (MPS). The structures of PMPOSS were confirmed by FTIR, NMR, and MALDI-TOF MS, indicating eight cage structures with different ratios of phenyl and methacryloxypropyl appeared. After that, the PMPOSS was diluted with different concentrations of styrene to explore the best curing formula. The bending test results demonstrated PMPOSS diluted by 20 wt% styrene (PMPOSS20) possessed good mechanical properties, however, PMPOSS0 (self-polymerization of PMPOSS) had the lower values of peak-HRR, THR, TSR, and peak-SD, which were reduced by 44.4%, 21.7%, 49.1%, and 33.8% in comparison to PMPOSS20, respectively. In addition, pyrolysis products were analyzed in detail by TGA-FTIR and Py-GC-MS. The results showed that large amounts of inflammable organic compounds were released from PMPOSS20 caused by the polystyrene fragments and methacryloxypropyl.

Catalytic removal of gaseous styrene using DBD combined with NiO/Pyrite composite

Nickel oxide and pyrite (NiO/Pyr) composites were prepared by impregnation method and employed in the dielectric barrier discharge (DBD) catalytic removal of gaseous styrene. The properties of the NiO/Pyr composites were characterized systematically. The removal efficiencies of styrene and energy yields had been examined as a function of initial concentration of styrene, gas flow rates and input powers. The results showed that the NiO/Pyr composite had excellent catalytic performance in DBD removal of gaseous styrene while mass ratio of NiO and Pyr was 0.2 and calcined temperature was 500 °C. When the initial concentration of styrene was 240 mg m−3, DBD combined with the NiO/Pyr composite could improve the removal and mineralization efficiency from 89.9% to 69%–98.6% and 78.5%, respectively, as compared with bare DBD system. The possible removal pathways were proposed based on the product identification by FTIR and GC-MS.

Preparation of ZSM-5 containing vanadium and Brønsted acid sites with high promoting of styrene oxidation using 30% H2O2

Design and synthesis of low cost and efficacious industrial catalyst for the oxidation of styrene has been an important research project. Herein, ZSM-5 zeolite containing tetrahedral vanadium (V) and Brønsted acid sites (V-H-ZSM-5) was prepared, and identified by characterizations such as XRD, SEM, UV–vis, NH 3 -TPD, H 2 -TPR N 2 -adsorption/desorption and FTIR. V-H-ZSM-5 performed extremely enhanced catalytic activity for the oxidation of styrene with 30% H 2 O 2 at 40 °C. Moreover, in-situ FTIR spectrum was used to investigate the catalytic mechanism. The results demonstrate that Brønsted acid site could not only increase the adsorption concentration of styrene in the micropores of V-H-ZSM-5 via the π complex interaction between double bond of styrene and Brønsted acid sites, but also increase the oxidation potential of H 2 O 2 . The synergetic action of tetrahedral vanadium (V) and Brønsted acid enhanced the catalytic activity for the oxidation of styrene with 30% H 2 O 2 . Impressively, V-H-ZSM-5 performed high reusability within five runs at a low reaction temperature (40 °C) for the first time.

Removal of styrene by the synthesized ZnO nanoparticles coated on the activated carbon adsorbent in the presence of UV irradiation

Background: Volatile organic compounds are the major environmental pollutants causing adverse effects on the human health and the environment, therefore, tremendous effort has been put toward eliminating these compounds. Methods: In this study, the effect of synthesized nanoparticles on the removal of styrene from gas phase by photocatalytic process under UV irradiation in the cylindrical photoreactor was studied. The activated carbon-zinc oxide (AC-ZnO) catalysts were prepared at different weight ratios (6%, 12%, and 18%) of ZnO. The prepared catalyst was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) analyses. The effects of various parameters, such as concentrations of styrene, various weight percentage (wt%) of nanoparticles, and UV irradiation, were investigated. The efficiency of the AC-ZnO catalyst was determined based on its adsorption capacity, breakthrough time, and removal efficiency. Results: It was revealed that the photocatalytic removal efficiency of styrene was high in the presence of both ZnO nanoparticle and AC under UV light. Under optimal conditions, the efficiency of UV/ACZnO 18%, UV/AC-ZnO 12%, and UV/AC-ZnO 6% catalysts was 77%, 86%, and 83%, respectively. By increasing the concentration of input styrene, the photocatalytic removal efficiency was reduced, while the adsorption capacity of styrene increased. Conclusion: According to the results, the AC-ZnO 12% exhibited higher activity compared to other photocatalysts. Also, the amount of stabilized ZnO nanoparticles on the activated carbon affects the elimination rate of styrene.

Genome engineering of E. coli for improved styrene production

Microbial production of exogenous organic compounds is challenging as biosynthetic pathways are often complex and produce metabolites that are toxic to the hosts. Biogenic styrene is an example of this problem, which if addressed could result in a more sustainable supply of this important component of the plastics industry. In this study, we engineered Escherichia coli for the production of styrene. We systematically optimized the production capability by first screening different pathway expression levels in E. coli strains. We then further designed and constructed a transcription regulator library targeting 54 genes with 85,420 mutations, and tested this library for increased styrene resistance and production. A series of tolerant mutants not only exhibited improved styrene tolerance but also produced higher styrene concentrations compared to the parent strain. The best producing mutant, ST05 LexA_E45I, produced a 3.45-fold increase in styrene compared to the parent strain. The produced styrene was extracted via gas stripping into dodecane and used in a direct free radical synthesis of polystyrene.

Changes in the concentration of volatile organic compounds and aldehydes in newly constructed houses over time

Nowadays, people spend most of their time indoors; thus, the indoor environment greatly affects human health because of exposure to chemicals indoors. Thus, in collaboration with Japanese house builders, a list of building materials having low volatile organic compound concentrations was compiled herein. The air-quality samples from seven newly built houses (seven bedrooms and seven living rooms) were collected and tested for 64 volatile organic compounds and two aldehydes. Air samples were obtained from the house with no furniture or household goods and were sampled 1 week after construction and repeated after a month. Furthermore, the test results with a 2009 survey of indoor air quality in newly constructed houses were compared. One week after construction, the xylene, styrene, toluene, formaldehyde, and ethylbenzene concentrations were less than half the standard guideline values set in Japan. The main substances detected in the samples were 2-butanone, acetone, ethanol, ethyl acetate, butyl acetate, and undecane. The statistical significance of the changes in substance concentrations over time was examined via Wilcoxon signed-rank test. One month after construction, the concentrations of all chemical substances had undergone a statistically significant reduction, except butyl acetate. The median of total volatile organic compounds in living rooms was 291 µg/m3, and the maximum was 354 µg/m3; both were under Japan’s provisional total volatile organic compound target of 400 µg/m3. These values were significantly lower than those recorded by other researchers. This study concludes that using experimentally identified low volatile organic compound materials effectively improves the indoor air quality.

Surfactant-free emulsion copolymerization of styrene and a cationic comonomer with two positively charged groups

Near-monodisperse, stabilized latex particles were prepared by surfactant-free emulsion copolymerization of styrene with a water-soluble cationic comonomer StMV having two positively charged groups. Unlike previously reported surfactant-free emulsion copolymerization systems, very small polymer nanoparticles (≤ 70 nm as indicated by transmission electron microscopy studies) were produced even though the StMV/St molar ratio was no more than 1/100. The effects of initiator concentration, StMV concentration, and styrene concentration on the size of the latex particles were investigated. The polymerization kinetics was monitored by transmission electron microscopy, monomer conversion, dynamic light scattering, and visual inspection. This study is expected to enrich the surfactant-free syntheses of cationic polystyrene latex and can provide useful information to construct cucurbit[n]uril-based supramolecular polymer colloids.