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Microplastics pollution in nearshore marine environment has become increasingly prominent and has received widespread attention. As a major leisure and entertainment place in coastal cities, bathing beaches not only provide an environment for microplastics to enter the ocean, but also provide a place for the retention of microplastics. In this paper, the distribution, composition and seasonal variation of microplastics in seawater and sediments of six bathing beaches along the coast of Qingdao were studied. The results showed that the average abundance of microplastics in the sediments of the Qingdao bathing beach was 91.11 ± 26.76 items/m2 (13.77 ± 4.39 items/kg) in the winter and 147.78 ± 34.80 items/m2 (21.98 ± 5.97 items/kg) in the summer. The microplastic abundance in the seawater in the summer (average: 567.50 ± 101.06 items/m3) was significantly higher than that in the winter (average: 326.11 ± 49.03 items/m3, p 0.05). To an extent, it can reflect the correlation between the abundance of microplastics and human recreational activities. The microplastics detected at the bathing beaches were mainly lines (80.5%) and fragments (7.9%) with a size range of 100 to 1000 μm. Rayon (41.8%) and polyethylene terephthalate (PET, 16.9%) were the main polymer types. The microplastic characteristics showed significant seasonal differences, more diversity in summer than in winter. These results emphasized that the distribution and movement of microplastics in bathing beaches were affected by seasons, human activities and coastal currents.

Due to the deterioration of the environment, the environmental protection has received more and more attention from the world. Various countries have established regulations to strictly limit the emission of organic volatiles (VOC) in paints. Solvent-based paints contain a large amount of VOC components, which not only pollutes the environment and wastes resources but also endangers people's health. Waterborne polyester coatings as representative waterborne coatings have become the development direction of coatings. In this study, a novel waterborne unsaturated polyester was synthesized by melt polycondensation and its water solubility was regulated by changing the amount of sodium sulfonate group. Then, a series of UV curable polyester networks were obtained utilizing the waterborne unsaturated polyester and multifunctional thiols via thiol–ene click reaction. The water resistance, gel content and mechanical properties of the films were characterized. It was found that the UV-cured films exhibited excellent physical properties including adhesion (1), pencil hardness (5 H), water resistance and contact angle (105.36). This shows that it is feasible to prepare high-performance UV-cured films based on thiol-ene click chemistry.

Unsaturated polyesters, in particular unsaturated polyesters with low volatility or without styrene, are gaining increasing importance in gel coatings, adhesives and molding resins. However, the cured unsaturated polyesters are usually described as non-degradable polyesters, which will lead to environmental and safety problems. In this paper, a kind of unsaturated copolyester with different binary acid composition, named poly (butylene succinate-co-butylene itaconic) (PBISx), was synthesized. Then, a photo-curable polyester(CPBIS) which can degrade under certain conditions was obtained by thiol - ene click reaction without adding styrene curing agent. The physical properties of unsaturated polyester PBISx can be effectively controlled by changing the ratio of raw materials, such as Tg from - 23.7 oC to - 45.2 oC, Xc from 38% to 14%, and Tm from 109.6 °C to 74.9 °C. It was found that CPBIS completely lost its degradability in lipase when its gel rate exceeded 98%. However, CPBIS could be degraded in GSH regardless of the gel rate, and lipase resumed its degradation in the GSH/lipase mixture, and the degradation rate reached 12% at 70h, attributed to the selective degradation of C-S-C bond by GSH and the secondary degradation of ester bond by lipase.

The morphology and aspect ratio of calcium sulfate hemihydrate (HH) are successfully controlled using AlCl3 as a morphology modifier in the hydrothermal synthesis process. As the concentration of AlCl3 is increased from 0 to 7.5 × 10−2 mol L−1, the crystal length decreases from 130 μm to 0.1–0.3 μm and the corresponding aspect ratio declined dramatically from 150–240 to 1–2, and the crystal morphology gradually changes from whiskers to rods, and even irregular nanogranules. The preferential adsorption of Al3+ on the side facets of HH would lower the surface energy and inhibit the elongation along these facets. The doping of Al3+ in the HH would destroy the main chain of HH and inhibit the elongation along the [001] direction. The two facts contribute to the morphology control. This work exhibits an efficient method to control the morphology of HH over a large range of size by simply adjusting the concentration of AlCl3.

There are three types of international structures: the international capacity structure, the international institutional structure, and the international ideational structure. With the ongoing change of contemporary international system structures, emerging countries such as China are trying to participate in the process of reshaping the international structures, which is the background of the Belt and Road initiative (BR). Accordingly, this chapter explores, with a specific emphasis on the ideational structure, how China’s BR furthers the change in the existing international structures on the one hand, while the changes in the international system can also become a barrier to the initiative’s realization the on the other.

In this paper, differential scanning calorimetry (DSC) was used to analyze the reaction kinetics of powder coatings. The effects of oxidized polyethylene wax (OPEW) on the curing process of powder coatings were investigated by exploring the curing process of OPEW-Owt% and OPEW-8wt% powder coatings. The Tg of OPEW-8wt% powder coating was 57.1 °C, which was greater than the Tg of OPEW-Owt% powder coating, indicating that OPEW increased the storage stability of the system. The apparent activation energy (Ea) of the two powder coatings was investigated by the Kissinger and Doyle-Ozawa equations. The Crane empirical equation was used to calculate the curing reaction order (n) of the two powder coatings, and the curing kinetics was discussed. The Ea of OPEW-0wt% was 64.35 kJ⋅mol-1, and the Ea of OPEW-8wt% was 60.95 kJ⋅mol-1, indicating that OPEW could promote the curing reaction.

In this paper, powder coating was prepared by melt extrusion method with polyester resin and pigment filler used as raw materials, oxidized polyethylene wax (OPEW) as dispersant, triglycidyl isocyanurate (TGIC) as curing agent, monoalkoxy titanate (i-C3H7OTiX3, X stands for fatty acid group, phosphate group, pyrophosphate group, etc.) as coupling agent (Titanate coupling agent covers the surface of inorganic pigment filler in the state of single molecule, replacing the original adsorption of trace water and gas. Meanwhile, the hydrophobic X group of long carbon chain will combine with the base material physically and chemically, effectively improving the interface state between inorganic and organic matter.), leveling agent and benzoin as additives. The gelation time of the powder coating was tested by a gelation time meter. The gloss of the coating film was tested by a gloss meter. The influence of the OPEW on the gelation time and gloss of the powder coating was investigated. The structure changes of the powder coating before and after solidification were analyzed by Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) was used to observe the dispersibility of OPEW on pigments and to explore the effect of OPEW types and dosages on dispersibility. Differential Scanning Calorimetry (DSC) analysis and thermogravimetric analysis (TG) were used to analyze the effect of OPEW on the thermal properties of powder coatings. The influence of OPEW on the hardness, impact property and adhesion of solidified film of powder coating was analyzed by mechanical property test. The results show that the gelation time of powder coatings decreases with the increase of OPEW content. This is because OPEW has the function of extinction. Due to the extinction of OPEW, the glossiness of powder coatings decreases with the increase of OPEW content. OPEW promotes the dispersion of pigments and fillers in powder coatings, and when the content of OPEW is 8 wt%, the dispersion performance of pigments and fillers is the best. OPEW improves the hardness, impact performance and adhesion of the film. The relevant film has excellent mechanical properties: hardness can reach 6H + 1750 g, impact performance is 50 cm, adhesion is level 0. The torque of powder coatings containing OPEW is lower than that of powder coatings without OPEW, and the time of torque balance is shorter. OPEW could improve the Tg of the coating. Because OPEW improves the dispersion of pigments and fillers in the system, it makes the mixing of polyester resin, pigments and fillers more uniform, and increases the molecular attraction among them. OPEW can increase the initial decomposition temperature T0 and the maximum decomposition rate temperature of the coating film and increase the maximum use temperature. However, excessive addition of OPEW would affect the final stability, and the stability of the OPEW-2 wt% sample is best. OPEW-0 wt%, OPEW-2 wt% and OPEW-5 wt% powder coatings have the best water resistance.

The research on UV curing kinetics of waterborne polyester is the basis for regulation of film formation rate. In this paper, a kind of reinforcing agent, namely polyhedral oligomeric silsesquioxanes (POSS), is adopted as modifiers to enhance hydrophobicity and adhesion of polyester coatings, and the effect of POSS on the thiol-ene UV curing kinetics including with the aspects of activation energy, reaction order and control steps are investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR). The results show that POSS is not found to significantly affect the reaction order, but change the activation energy obviously. A small amount of POSS can affect the click reaction rate of thiol-ene. The UV curing reaction rate of thiol-ene modified by POSS is mainly controlled by propagation growth rate. There is a resistance parameter in the reaction process, which can effectively control the reaction rate of thiol-ene UV curing of waterborne polyester.

The bio-based and biodegradable polyester poly(butylenes 2-methylsuccinate) (PBM) was successfully used as a polymeric plasticizer to modify poly(vinyl chloride) (PVC) in this work. The tensile properties, plasticization efficiency estimated by the lowered glass transition temperature and the enhanced elongation at break of the PVC/PBM blends and the migration stability of the PBM were investigated. It was indicated that the migration-resistant property of PVC plasticized with PBM was greatly superior to that with dioctyl phthalate (DOP). Furthermore, the tensile properties were comparable to that of PVC/DOP, indicating that the environmentally friendly PBM can be used as an alternative plasticizer to remove the potential health risks from migrating phthalates during applications.

Amphoteric polyacrylamide was prepared by dispersion polymerization with acrylamide, dimethylaminoethyl methacrylate methyl chloride, and acrylate acid as monomers, ammonium sulfate (AS) aqueous solution as a reaction medium, poly(dimethylaminoethyl methacrylate methyl chloride) (PDMC) as a stabilizer, and 2,2′-azobis(2-amidinopropane) dihydrochloride as an initiator. The influence of particle morphology on AmPAM dispersion and other factors and polymerization were investigated. Three crucial factors responsible for particle morphology are the dispersant concentration, sodium chloride concentration, and ionic degree of terpolymer. The ammonium sulfate concentration had relatively less of an effect on particle morphology, but a suitable concentration was necessary to obtain a stable dispersion system. A higher concentration of PDMC could yield more uniform and spherical particles during dispersion polymerization. A small amount of sodium chloride can decrease particle size and dispersion viscosity. These four factors heavily influenced the viscosity of polymer dispersion, and they had a large effect on the intrinsic viscosity of AmPAM except for the AS and NaCl concentration. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E212–E220, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21264

A cationic polyelectrolyte of P (CMTC-AM-DMC) was synthesized by dispersion polymerization in aqueous solution of ammonium chloride, with acrylamide and dimethylaminoethyl methacrylate methyl chloride as main raw materials. N-carboxymethylthioureidochitosan was used as both the reactant and the stabilizer, and 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50) as the initiator. The effects of the major reaction variables such as the concentration of inorganic salt and initiator, temperature, reaction time, and pH on the polymerization were discussed in this article. The optimal conditions of the polymerization were determined by orthogonal tests. The results showed that an increase in salt concentration resulted in an increase of molecular weight and particle size and a decrease of apparent viscosity, while when salt concentration was up to 23.9%, apparent viscosity was slightly higher than others. Molecular weight, particle size, and apparent viscosity all decreased with the increase of initiator. The apparent viscosity, molecular weight, and particle size would decrease with pH, and the product would be coagulated when pH > 7. Temperature influenced the characteristic a lot. Overall conversion was less dependent on these factors except for the temperature. Molecular weight and overall conversion increased gradually with the time, and the monomers could react completely at about 5–7 h. Flocculation occurred with 13% of salt concentration, 0.005% of initiator, and pH > 7. The optimal reaction conditions for obtaining a stable aqueous dispersion were 22.3% for ammonium chloride, 0.007% for initiator, react under 55 °C for 5 h at pH = 4. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Amphoteric polyacrylamide (AmPAM) was prepared successfully through seeded dispersion polymerization with acrylamide, methacrylatoethyl trimethyl ammonium chloride and acrylic acid as comonomers in ammonium sulfate solution. It was characterized by 1H nuclear magnetic resonance (1H NMR) and elemental analysis. The particle morphology and apparent viscosity of polymer dispersion were obtained by optical microscope and rotary viscometer, respectively. AmPAM dispersion was obtained with low apparent viscosity. The process was smooth without high viscosity stage. The data of 1H NMR spectrum and elemental analysis indicated that all monomers had participated in the polymerization. The seeded reaction time and the mass ratio of two parts of monomers had significant effects on the dispersion polymerization. The best conditions were seeded reaction time 1.75h and the mass ratio 0.75. The apparent viscosity of AmPAM dispersion depended on the number of particles, particle size and low molecular weight polymer concentration in the continuous phase. AmPAM showed both anti-polyelectrolyte effect and polyelectrolyte effect. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Two sodium nonylphenol ethoxylate(10) sulfoitaconate ester surfactants, namely disodium nonylphenol ethoxylate(10) sulfoitaconate monoester (DNE(10)SIM) and sodium nonylphenol ethoxylate(10) sulfoitaconate diester (SNE(10)SID), were synthesized through the esterification and sulfonation reactions with nonylphenol ethoxylate(10) ester, itaconic acid and sodium sulfite as the raw materials. The chemical structures of the prepared surfactants were confirmed by FTIR and 1H NMR. The surface tension of the synthesized surfactants was measured at 25 °C and the surface active properties were characterized. The DNE(10)SIM had better surface activity. The CMC was 1.77 × 10−6 mol L−1 and γCMC was 35.45 mN m−1. The CMC and γCMC for the SNE(10)SID were 5.42 × 10−5 mol L−1 and 37.67 mN m−1, respectively. Moreover, the emulsification power of SNE(10)SID was better.

The terpolymer of acrylamide (AM), dimethylaminoethyl methacrylate methyl chloride (DMC), and acrylic acid (AA) was synthesized with their molar ratio of 70 : 15 : 15 through dispersion polymerization in aqueous solution of ammonium sulfate (AS), using poly(dimethylaminoethyl methacrylate methyl chloride) (PDMC) as stabilizer and 2,2′-azobis(2-amidinopropane) dihydrochloride (V-50) as initiator. The particle size of the terpolymer ranged from 5 to 8 μm and the intrinsic viscosity was from 5.5 to 11.6 dL g−1. The terpolymer had anti- polyelectrolyte effect under low AS concentration, but polyelectrolyte effect with the concentration beyond 10%. Polymerization dispersion with low apparent viscosity, uniform particles, good stability, and high molecular weight terpolymer was obtained in single stage. The effects of varying concentrations of salt, stabilizer, and monomers on particle morphology and intrinsic viscosity were investigated. With increasing concentration of AS and PDMC, the intrinsic viscosity of terpolymer increased, then decreased afterward. However, it increased gradually with increase in monomer concentration. The particle size was enlarged with increasing of AS and monomer concentration and decreasing of PDMC concentration. The optimum condition was the concentrations of salt, stabilizer, and monomers 28%, 3.0%, and 8% to 15%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The copolymer of acrylamide (AM) and 2-acrylamide-2-methyl-propane sulfonate (AMPS) was synthesized through free radical dispersion polymerization in an aqueous solution of ammonium sulfate and poly(2-acrylamide-2-methyl-1-propane sulfonate) as a steric stabilizer. The average particle size of the copolymer ranged from 1.0 μm to 4.0 μm, and the molecular weight was 2.0 × 106 ~ 7.0 × 106 g mol−1. The swelling property of the dispersion copolymer was studied by characterizing the apparent viscosity and particle size distribution. When the dispersion was diluted with salt aqueous solution in which the ammonium sulfate concentration kept equal with that of the original dispersion, particle size and particle size distribution of the diluted dispersion changed little, compared with that of the original dispersion. While diluted with deionized water, particle size and particle size distribution could expand several times. The effects of the AMPS/AM molar ratios, the molecular weight of stabilizer, and the initiation temperature were investigated. It was found that with the increase of the AMPS/AM ratios, the molecular weight of copolymers increased, and then decreased. The particle size and conversion of monomers increased. The stability of the copolymer dispersion increased with increasing the molecular weight of stabilizer for a fixed stabilizer concentration. With the increase of the initiation temperature, the molecular weight of copolymer increased at first and then decreased gradually, but the particle size and conversion increased. The optimum conditions for the stable AMPS/AM dispersion were as follows: the AMPS/AM molecular ratio was 15/85, the molecular weight of the PAMPS stabilizer 3.0 × 105 ~ 4.0 × 105, and the initiation temperature 50 °С, respectively.

Swelling properties of amphoteric polyacrylamide (AmPAM) dispersions were investigated by measurements of apparent viscosity and particle morphology. AmPAM dispersion was prepared by dispersion polymerization in aqueous solution of ammonium sulphate. Changes of particles during dispersion polymerisation of AmPAM were simulated and compared with anionic and cationic polyacrylamide (APAM and CPAM, respectively). Sample viscosity and particle morphology were obtained using a rotational viscometer and optical microscope. It was found that small molecules or ions enter and swell particles in the AmPAM dispersion when (NH4)2SO4 concentration decreases. Similarly, monomers, including acrylamide, acrylic acid, and methacrylatoethyl trimethyl ammonium chloride, have the same effects on the AmPAM dispersion but the effect degree is different. Swelling properties of the AmPAM dispersion were different from those of the APAM and CPAM dispersions due to their different ionic nature, type of stabiliser, media, etc. Particles in the APAM or CPAM dispersions were swelled less than those in the AmPAM dispersion.