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While there are a number of available reference and testing materials for micro- and nanoplastic (MNP) studies in toxicology, they are not well-characterized and do not cover all major polymer types that may potentially pollute the environment. This review article will address the question of why we need properly designed synthesized micro- and nanoplastics with a core–shell structure (with organic–inorganic units) and provide researchers with a scientific basis for the design of synthesized MNP particles. It will include a list of commercially available MNPs, an overview of the theoretical background to polymer particle synthesis, and an analysis of the advantages and disadvantages of MNP preparation methods, namely, fragmentation and synthesis, along with examples of synthesized MNP particles. The current study will demonstrate that polystyrene is one of the most prevalent MNP particle types among reference materials from certification bodies and among testing particles synthesized by chemical scientists. Nevertheless, the global industrial production of polystyrene represents approximately 5% of the total, and it is not a dominant plastic type in the textile or packaging industries. In contrast to mechanically fragmented MNP particles, the synthesis approach offers the potential to control the physico-chemical properties, enabling the more selective detection and quantification, as well as a greater comparability of the results amongst toxicological studies. [ABSTRACT FROM AUTHOR]

Abstract Polyurethane elastomers are polymers that exhibit both outstanding stability and flexibility and are commonly used in the sector of building and construction to absorb vibrations. Long-chained linear molecules, more precisely macrodiols, are used as the soft phase within the elastomer. The tendency of the used polyetherols to crystallise within the polymer between −40 and + 30 °C, depending on the molecule's chain length, is a major disadvantage since consistent properties over a broad temperature range are desired to have no limitations considering the elastomers' application fields. In this work, crystallisation phenomena in polyurethane elastomers due to the long-chained polyetherol components were investigated in detail with DSC and DMA experiments. Possible measures to reduce these phenomena by changing the chemical constitution, were defined. Two kinds of short-chained polyols were introduced into the system to be combined with the long-chained polyetherol component, acting as diluents and creating different networks. As a bifunctional alcohol, 1,4-butanediol was chosen, creating a larger number of hard phases (physical cross-links) within the polymer. Glycerol was used as a trifunctional alcohol, responsible for covalent threedimensional linkages (chemical cross-links). The addition of 1,4-butanediol did not eliminate, but reduced the crystallisation tendency of the polyetherol component and led to a higher storage modulus above room temperature. If a certain amount of glycerol is added to the polymeric system, it prevents the cold crystallisation. Furthermore, glycerol reduced the drop of the storage modulus at elevated temperatures due to the chemical cross-links. Highlights • Crystallisation of polyurethanes depends on molecular weight of used polyetherol. • Addition 1,4-butanediol limits the crystallisation tendency. • Addition of glycerol prevents crystallisation. • Physical cross-links give strength to the material at room temperature. • Chemical cross-links function as reinforcers at elevated temperatures. [ABSTRACT FROM AUTHOR]

The effects of UV irradiation on iron(III)chloride doped poly(vinyl alcohol) (PVA) films, using a high molar mass polymer, have been studied. It has been found that the polymer is oxidized and crosslinked during UV irradiation. UV/VIS spectra reveal an exponential loss of absorption at λ = 360 nm, and the refractive index of the PVA:FeCl3 films decreases significantly during UV irradiation (Δ nD = −0.09). The effects of crosslinking have been studied using the sol-gel technique, which revealed high gel contents due to doping and UV-exposure. Photolithographic patterning of doped PVA films using a medium-pressure mercury-vapor UV source has been carried out, leading to good contrast behavior before and after development in aqueous media. A photobleaching effect was observed, therefore the curing of thicker films is feasible. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The aim of this study was the investigation of the use of modified talcum for supporting crosslinking and as novel nucleating agent for physical foaming of polyethylene. For the modification of the talcum, a thermal initiator was linked to the talcum surface. During the extrusion process, the initiator decomposes, and gas and radicals are formed. The gas generates the nucleation of cells and the radicals support the crosslinking process between the polymer chains. The modification of the talcum was performed in three steps: The first step was the grafting of alkoxysilanes onto the talcum surface. The second step was the chlorination of the thermal initiator for an easier linkage, and the last step was the linking between the initiator and the silanes grafted onto the talcum surface. For this study, two investigations were carried out. One investigation was the analysis of the crosslinking effect with the modified talcum. For this purpose, polyethylene plates were compression molded and the viscoelastic properties were measured with a parallel plate rheometer. The use of the modified talcum led to a higher crosslinking density. The second investigation was the physical foaming experiment in an extrusion process with nitrogen as blowing agent using both a pure and the modified talcum as nucleating agents. The foamed samples were characterized in terms of density, cell size and cell density, and compared with each other. The blend with the modified nucleating agent indicated a foam structure with a smaller mean cell size and a lower density compared to the use of the pristine nucleating agent. [ABSTRACT FROM AUTHOR]