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Interfaces between the photoactive layers and electrodes play critical roles in controlling the performance of optoelectronic devices. Herein, a novel nonconjugated polymer additive (nPA), poly(2-vinylpyridine) (P2VP), is reported for modifying the interfaces between the bulk-heterojunction (BHJ) and cathode/metal oxide (MO) layers. The P2VP nPA enables remarkably enhanced power conversion efficiencies (PCEs) and ambient stability in different types of polymer solar cells (PSCs). Importantly, interfacial engineering can be achieved during deposition of the P2VP nPA-containing BHJ active layer via simple, one-step solution processing. The P2VP nPA has much higher surface energy than the BHJ active components and stronger interaction with the surface of MO, which affords spontaneous vertical phase separation from the BHJ layer on the MO surface by one-step solution processing. The self-assembled P2VP layer substantially reduces the work function and surface defect density of MO, thereby minimizing the charge-extraction barrier and increasing the PCEs of the PSCs significantly, i.e., PTB7-Th:PC71BM (10.53%→11.14%), PTB7:PC71BM (7.37%→8.67%), and PTB7-Th:P(NDI2HD-T) all-PSCs (5.52%→6.14%). In addition, the lifetimes of the PSCs are greatly improved by the use of the P2VP nPA. [ABSTRACT FROM AUTHOR]

The study presents the possibility to use gel permeation chromatography (GPC) with atmospheric pressure chemical ionization (APCI)-mass spectrometry for the analysis of polymer additives having molecular weights up to 2,000 g mol−1. Irganox 1010, Irganox 1035, Irganox 1076, and Irganox 3114 were analyzed in chloroform using 2.1-mm-internal-diameter GPC columns at the optimum flow rate of 50 µL min−1. Based on the chemical formula, the APCI interface combined with chlorine ionization enabled us to predict the expected mass spectrum and to build libraries without needing to inject each additive separately. Quantification limits of about 100 µg of additive in 1 g of polymer (100 ppm) can be reached using single-ion-monitoring methods based on the calculated isotope distribution. [ABSTRACT FROM PUBLISHER]

Porous polymer microspheres have attracted great interest in many potential fields of application, such as controlled drug release, catalysis, and scaffolds, due to their high surface to volume ratio, low density, permeability, etc. It is desirable to control the porous structure of the microspheres to meet their application requirements. In this study hierarchically porous microspheres were prepared by the technique of non-solvent induced phase separation (NIPS) during electrospraying. Porous and/or hollow microspheres were prepared by using different non-solvents. The influence of humidity on the surface morphology and microstructure by vapor induced phase separation and breath figure effect were investigated. Microspheres with an irregularly hollow structure was observed with the increase of humidity, when ethanol was used as the non-solvent. On the other hand, the polymer additives in the solution could also affect the NIPS and thus the surface morphology of the electrosprayed microspheres. It was found that the microstructure of both the microsphere and surface pores varied little when the polymer additives were not soluble in the non-solvent (hexanol). When polyvinyl pyrrolidone (PVP – soluble in the hexanol) was used as the polymer additive, dimples on the microsphere surface were formed. [ABSTRACT FROM AUTHOR]

Recent advances in our understanding of CaCO3 nucleation from solution have provoked new and challenging questions. We have studied CaCO3 formation using precipitation by carbonate ester hydrolysis which ensures precipitation from a strictly homogeneous solution state and allows 'titrating' carbonate to a solution with a given Ca2+ concentration on a timescale suited for kinetic studies. Nucleation and crystallization were traced by combining dynamic light scattering (DLS) and transmission electron microscopy (TEM). DLS served as in situ technique to identify the nucleation time, to monitor particle size evolution, to discriminate different precipitation mechanisms and to validate reproducibility. TEM snapshots taken during different stages of the precipitation process identified different phases and morphologies. At a high level of supersaturation homogeneous nucleation in solution led to the formation of amorphous CaCO3 particles (Ø≈30 nm), which transformed via vaterite to calcite. Nucleation occurred uniformly in solution which appears to be unique for the CaCO3 system. In the presence of Na-polymethacrylate (Na-PMA), heterogeneous nucleation was suppressed and Ca-polymer aggregates were formed in the prenucleation stage. Beyond a critical threshold supersaturation CaCO3 particles formed in solution outside of these aggregates. The nucleation process resembled that without additive, indicating that Na-PMA exerts only a minor effect on the CaCO3 nucleation. In the postnucleation stage, the polymer led to the formation of extended liquid-like networks, which served as a precursor phase for solid ACC particles that formed alongside the network. [ABSTRACT FROM AUTHOR]

Chemical recycling of waste plastics has attracted growing global interest in recent years. However, the role that polymer additives play during these depolymerization reactions is still unknown. In this work, we investigate the impact of typical additives on the rate of reaction of pyrolysis and catalytic decomposition over zeolites. Further, we regenerate the spent catalysts after contact with additive-containing polymer and assess modifications to the catalyst structure and activity. All the tested additives were found to hinder the activity of ZSM-5 catalysts. We also unveil that some additives (amines, phenols) can be fully removed from the catalyst via calcination, whereas others (phosphites, metallic stearate) may permanently deposit and modify sites. The deposition of such impurities on zeolites may change their alkane cracking capabilities. After regeneration, zinc deposited on the catalyst (resulting from plastic degradation reactions) was able to increase hexane cracking conversion by over 7-fold when compared to fresh ZSM-5. [Display omitted] • The presence of tested additives does not significantly influence the rates of polyethylene pyrolysis at high temperatures. • Polymer additives lower the rate of polyethylene cracking by acid catalysis. • Phosphorus and zinc within additives were not removed via calcination and permanently deposit on catalysts. • The presence of deposited zinc increases zeolite activity and increases its selectivity towards aromatics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The strategy of noncrystallographic branching to fabricate hierarchical materials is proposed. • Spherulitic hierarchical HNS with excellent specific surface area is prepared. • The mechanism of polymer additives inducing noncrystallographic branching is verified. In this work, the micro/nano spherulitic hierarchical 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) with the excellent specific surface area was prepared for the first time, which was expected to overcome the agglomeration problems of nanoscale HNS. In detail, poly(N -isopropyl acrylamide) (PNIPAM), polysuccinimide (PSI), and polyvinylpyrrolidone (PVP) were selected as additives to induce forming spherulitic HNS. Leaflike crystals were obtained in the presence of PNIPAM, while spherulitic HNS could be fabricated in the presence of PSI or PVP. And the prepared spherulitic HNS owned nearly 6 times the specific surface area of the raw HNS, with decreased impact sensitivity and advanced melting and decomposition temperatures, demonstrating a good desensitization effect, and a favorable energy release of the hierarchical structure. Moreover, morphological changes under the effect of the molecular weight and concentration of PVP were explored. The approximated morphological evolution of spherulitic HNS was consistent with the classical spherulitic growth by noncrystallographic branching. Furthermore, it was verified that preferential adsorption of PVP and PSI on the HNS inhibits the growth steps of the (200) face and introduces stress to generate crystal defects, which triggers noncrystallographic branching and further spherulitic growth. Overall, the strategy of fabricating micro/nano spherulitic hierarchical energetic materials via polymer-additive induced noncrystallographic branching is promising to solve the problems of nanoscale energetic materials in agglomeration and microscale bulk crystals in low activity. [ABSTRACT FROM AUTHOR]

Since the emergence of organometal halide perovskite (OMP) solar cells, there has been growing interest in the benefits of incorporating polymer additives into the perovskite precursor, in terms of both photovoltaic device performance and perovskite stability. In addition, there is interest in the self-healing properties of polymer-incorporated OMPs, but the mechanisms behind these enhanced characteristics are still not fully understood. Here, we study the role of poly(2-hydroxyethyl methacrylate) (pHEMA) in improving the stability of methylammonium lead iodide (MAPI, CH 3 NH 3 PbI 3 ) and determine a mechanism for the self-healing of the perovskite-polymer composite following exposure to atmospheres of differing relative humidity, using photoelectron spectroscopy. Varying concentrations of pHEMA (0-10 wt %) are incorporated into a PbI 2 precursor solution during the conventional two-step fabrication method for producing MAPI. It is shown that the introduction of pHEMA results in high-quality MAPI films with increased grain size and reduced PbI 2 concentration compared with pure MAPI films. Devices based on pHEMA-MAPI composites exhibit an improved photoelectric conversion efficiency of 17.8%, compared with 16.5% for a pure MAPI device. pHEMA-incorporated devices are found to retain 95.4% of the best efficiency after ageing for 1500 h in 35% RH, compared with 68.5% achieved from the pure MAPI device. The thermal and moisture tolerance of the resulting films is investigated using X-ray diffraction, in situ X-ray photoelectron spectroscopy (XPS), and hard XPS (HAXPES). It is found that exposing the pHEMA films to cycles of 70 and 20% relative humidity leads to a reversible degradation, via a self-healing process. Angle-resolved HAXPES depth-profiling using a non-destructive Ga Kα source shows that pHEMA is predominantly present at the surface with an effective thickness of ca. 3 nm. It is shown using XPS that this effective thickness reduces with increasing temperature. It is found that N is trapped in this surface layer of pHEMA, suggesting that N-containing moieties, produced during reaction with water at high humidity, are trapped in the pHEMA film and can be reincorporated into the perovskite when the humidity is reduced. XPS results also show that the inclusion of pHEMA enhances the thermal stability of MAPI under both UHV and 9 mbar water vapor pressure.

Geosynthetics is the umbrella term for thin, flexible material sheets applied in civil and environmental engineering, of which geotextiles form the largest group. Most geotextiles consist of a polymer from the polyolefin, polyester or polyamide family, and additives to improve their stability. The polymer may degrade into microplastic particles over time and under various conditions and can cause adverse effects, as species may ingest these particles or encounter adverse effects due to the interference of the particles with e.g. their photosynthesis system in the case of algae. Leaching of additives may occur from the intact material, as they are often not covalently bound to the polymer backbone, but is greatly enhanced when micro-sized plastic particles have been formed. A total of 42 polymer additives were identified, of which 26 had ecotoxicity information available in terms of a REACH persistence, toxicity and bioaccumulation (PBT) assessment. Of these, 15 were classified as (very) persistent and 2 as toxic. A survey to assess potential toxicity of the remaining 16 substances revealed that no ecotoxicity studies had been performed on 13 of these compounds. For 3 compounds, other toxicity data was found, as well as of several chemical groups known to be used as additives in geotextiles. The current knowledge is thus lacking in two domains: on the one hand, ecotoxicity data is scarce as many substances have not yet been the subject of ecotoxicological studies. On the other hand, in situ toxic effects might be missed by the current approach of single compound toxicity testing. Moreover, environmental occurrence data of the additives are extremely scarce. [ABSTRACT FROM AUTHOR]

Three low-cost propeller-shaped small molecules based on a triphenylamine core and the high-performance donor molecule 7,7′-[4,4-bis(2-ethylhexyl)-4 H-silolo[3,2- b:4,5- b′]dithiophene-2,6-diyl]bis[6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[ c][1,2,5]thiadiazole] (DTS(FBTTh2)2) were investigated as hole-transporting materials in perovskite solar cells. Each hole-transporting material was designed with highly modular side arms, allowing for different bandgaps and thin-film properties while maintaining a consistent binding energy of the highest occupied molecular orbitals to facilitate hole extraction from the perovskite active layer. Perovskite solar cell devices were fabricated with each of the three triphenylamine-based hole-transporting materials and DTS(FBTTh2)2 and were compared to devices with 2,2′,7,7′-tetrakis( N, N-di- p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) hole-transporting layers. Each of our triphenylamine hole-transporting materials and DTS(FBTTh2)2 displayed surface morphologies that were considerably rougher than that of spiro-OMeTAD; a factor that may contribute to lower device performance. It was found that using inert, insulating polymers as additives with DTS(FBTTh2)2 reduced the surface roughness, resulting in devices with higher photocurrents. [ABSTRACT FROM AUTHOR]

Polymer items are extensively present in the human environment. Humans may be consequently exposed to some compounds, such as additives, incorporated in these items. The objective of this work is to assess the human exposure to the main additives such as those authorized in the packaging for pharmaceutical products. The urinary matrix was selected to optimally answer this challenge because it has already been proven that the exposure to chemicals can be revealed by the analysis of this biological matrix. A multi-residue analytical method for the trace analysis at ng/mL in human urine was developed, and consisted of an extraction of analytes from urine by solid phase extraction (SPE) and an analysis by ultra-high performance liquid chromatography coupled to a tandem mass spectrometer (UHPLC–MS/MS). Even if the quantification of these compounds was an analytical challenge because of (i) the presence of these substances in the analytical process, (ii) the diversity of their physicochemical properties, and (iii) the complexity of the matrix, the optimized method exhibited quantification limits lower than 25 ng/mL and recoveries between 51% and 120% for all compounds. The method was validated and applied to 52 human urines. To the best of our knowledge, this work presents the first study allowing the assessment of the occurrence of more than twenty polymer additives at ng/mL in human urine. [ABSTRACT FROM AUTHOR]

The fracture of single-component molecular glasses has been characterized under tension. In-plane tension is created by cooling a liquid film below its glass transition temperature constrained on a substrate that is less thermally expansive. The fracture produces a network structure whose cell size is comparable to film thickness. For each system studied (indomethacin, o -terphenyl, and sucrose benzoate), the condition of fracture is well described by the fracture models for supported films and a characteristic energy release rate G c . Agreement is found for a wide range of film thickness (10–250 μm) in both open and sandwich geometries. For the molecular glasses studied, G c ≈ 1 J/m 2 . o- Terphenyl glasses become significantly more resistant to fracture with the addition of polystyrene; at 10 wt.%, G c increases with the molecular weight of polystyrene, by a factor of 5 at 1 million g/mol. The molecular-weight dependence is consistent with an increase of fracture surface area as the crack tip goes around the pervaded volume of each polymer chain encountered (sphere defined by the radius of gyration). [ABSTRACT FROM AUTHOR]

The physicomathematical model of migration of polymers in a liquid turbulent flow in a pipe is based on a comparison of forces transverse to the motion of the mainstream flow: the Saffman, Magnus, and turbophoresis forces. It has been shown that the polymer particles are grouped near a certain boundary within the limits of the boundary layer. On this basis, the authors have made assumptions on the mechanism of suppression of turbulent pulsations and decrease in the viscous friction near the wall, which makes up the Toms effect. The proposed model satisfies, at least, qualitatively, various actually observed manifestations of the effect. [ABSTRACT FROM AUTHOR]

Polymers are effective drag reducers owing to their ability to suppress the formation of turbulent eddies at low concentrations. Existing drag reduction methods can be generally classified into additive and non-additive techniques. The polymer additive based method is categorized under additive techniques. Other drag reducing additives are fibers and surfactants. Non-additive techniques are associated with the applications of different types of surfaces: riblets, dimples, oscillating walls, compliant surfaces and microbubbles. This review focuses on experimental and computational fluid dynamics (CFD) modeling studies on polymer-induced drag reduction in turbulent regimes. Other drag reduction methods are briefly addressed and compared to polymer-induced drag reduction. This paper also reports on the effects of polymer additives on the heat transfer performances in laminar regime. Knowledge gaps and potential research areas are identified. It is envisaged that polymer additives may be a promising solution in addressing the current limitations of nanofluid heat transfer applications. [ABSTRACT FROM AUTHOR]

A comparative study of the properties of poly(decyl methacrylate) and decyl methacrylate copolymers with N-tert-nonylacrylamide as viscosity index improver-dispersant additives for petroleum oils has been performed. Tests in the I-20A oil have shown that the introduction of substituted acrylamide units improves the thickening and dispersing properties of the poly(meth)acrylate additives, but it reduces their resistance to mechanical degradation. [ABSTRACT FROM AUTHOR]

An original approach for copper electroless deposition without the use of the palladium catalysts is developed. The mixture of two hydrophilic polymers, forming polymer–polymer complex and an assembly with ethylenediaminetetraacetic acid (EDTA)–Cu(II) one is the essential element of the method proposed. Two pairs compatible polymer mixtures (polyethylene glycol (PEG) – ethyl cellulose (EC) and PEG – poly(dimethylaminoethylmethacryloyl propanesulfonate), (PDMAPS) are tested. It is shown that these polymer additives do not change the UV- and EPR-spectra, as well as the current–voltage curve characteristics, which is related to the fact that in the presence of these polymer additives there is not the formation of new compounds with absorbance in the UV- and visible regions and new paramagnetic centers, as well as that they don’t influence the formaldehyde oxidation potential and Cu(II) reduction one. At the same time, these polymer additives decrease the deposition rate, improve the homogeneity, surface coverage and adhesion of the copper film to the substrate. These results correlate with the nonlinear viscosity elevation of the electroless bath with polymer additives, as well as with the maximal values of the critical angle for the first movement of the drop on the inclined substrate plane and of the difference between front and back contact angles of the drop from the electroless bath with polymer additives too. This correlation is related to the formation of the polymer–polymer complex, cross-linked with Cu(II)–EDTA as physical junction points, multisite adsorption of this enriched with Cu(II) network on the substrate surface, the precondition for a autocatalytic copper electroless deposition, more smooth substrate coverage, and improved adhesion of the copper film to the substrate surface. [ABSTRACT FROM AUTHOR]

Highlights: [•] Constructability and volumetric characteristics are not affected by polymers. [•] Polymers are analogous (or better) to modified bitumen, in terms of modulus. [•] Polymers reduce temperature and frequency susceptibility of bituminous mixtures. [•] Bituminous mixtures fatigue life is improved by using polymer additives. [•] The addition of polymers improves the rutting resistance of bituminous mixtures. [ABSTRACT FROM AUTHOR]

Turbulent drag reduction has been observed to occur over a wide range of additive systems, such as solution of synthetic or natural polymers, and fibre suspensions. In this study, the influence of softwood kraft pulp fibres and synthetic polymer additives on turbulent drag reduction (DR) in a hydrocyclone is investigated. It was demonstrated that cellulose fibre suspensions and aqueous polymeric solutions reduce the fluid energy losses in comparison to water during hydrocyclone operation within the range of reject ratios studied. A maximum drag reduction of 58 % and 55 % was found to occur at a volume split fraction of 50 % for a 0.9 % fibre suspension and a 300 ppm anionic polyacrylamide solution, respectively. Polymer degradation or polymer chain decay displayed adverse effects for 100 ppm and 150 ppm solutions after 22 min of run time at 11.2 kW pumping power and a reject ratio of 25 %. Synergistic effects were observed with pulp suspensions containing both cationic and anionic polyacrylamide (CPAM and APAM, respectively); a maximum DR of 41 % was observed for a 0.7 % fibre suspension containing 100-300 ppm of polymer at a reject ratio of 50 %. Similarly to aqueous polymer solutions, the degradation of 300 ppm APAM or CPAM in a 0.7 % fibre suspension decreased the observed DR up to 38 % after 30 min of run time at 11.2 kW pumping power and a reject ratio of 25 %. The near 43 % reduction in CPAM concentration, due to surface adsorption, when present in a 0.7 % fibre suspension assisted in quantifying the DR variations observed between suspensions containing APAM or CPAM. [ABSTRACT FROM AUTHOR]

Highlights: [•] Acrylic polymers with the additive Tinuvin 292 were exposed to heat or UV light. [•] Changes to the additive were investigated directly by ambient mass spectrometry. [•] Semi-quantitation was achieved using LESA-MRM analyses. [•] UV light caused demethylation of piperidinyl nitrogens in Tinuvin 292. [•] Demethylation is a necessary step for the antioxidative protection of polymers. [Copyright &y& Elsevier]

Concrete structures need repairing due to various reasons such as deteriorative effects, overloading, poor quality of workmanship and design failures. Cement based repair mortars are the most widely used solutions for concrete repair applications. Various factors may affect the bond strength between concrete substrate and repair mortars. In this paper, the effects of polymer additives, strength of the concrete substrate, surface roughness, surface wetness and aging on the bond between concrete substrate and repair mortar has been investigated. Full factorial experimental design is employed to investigate the main and interaction effects of these factors on the bond strength. Analysis of variance (ANOVA) under design of experiments (DOE) in Minitab 14 Statistical Software is used for the analysis. Results showed that the interaction bond strength is higher when the application surface is wet and strength of the concrete substrate is comparatively high. According to the results obtained from the analysis, the most effective repair mortar additive in terms of bonding efficiency was styrene butadiene rubber (SBR) within the investigated polymers and test conditions. This bonding ability improvement can be attributed to the self-flowing ability, high flexural strength and comparatively low air content of SBR modified repair mortars. On the other hand, styrene acrylate rubber (SAR) modified mortars was found incompatible with the concrete substrate. [ABSTRACT FROM AUTHOR]

An experimental measurement was performed using time-resolved particle image velocimetry (TRPIV) to investigate the spatial topological character of coherent structures in wall-bounded turbulence of polymer additive solution. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The comparisons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spatial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution compared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction. [ABSTRACT FROM AUTHOR]

Abstract: The friction-reducing effect of an adsorbed film at transverse roughness was investigated by focusing on the adsorption ability of polar compounds. Gradual reduction in friction under the low speed condition in case of the adsorbed film is formed from stearic acid or polymethacrylate. This is probably because the friction-reducing effect varied according to the adsorption ability and the number of the functional group. The results implied that the friction-reducing effect could be explained not only by the micro-EHL effect derived from transverse roughness but also by some other load-bearing effect, which depends on the formation state of the adsorbed film. [Copyright &y& Elsevier]

Direct numerical simulations (DNS) were performed for the forced homogeneous isotropic turbulence (FHIT) with/without polymer additives in order to elaborate the characteristics of the turbulent energy cascading influenced by drag-reducing effects. The finite elastic non-linear extensibility-Peterlin model (FENE-P) was used as the conformation tensor equation for the viscoelastic polymer solution. Detailed analyses of DNS data were carried out in this paper for the turbulence scaling law and the topological dynamics of FHIT as well as the important turbulent parameters, including turbulent kinetic energy spectra, enstrophy and strain, velocity structure function, small-scale intermittency, etc. A natural and straightforward definition for the drag reduction rate was also proposed for the drag-reducing FHIT based on the decrease degree of the turbulent kinetic energy. It was found that the turbulent energy cascading in the FHIT was greatly modified by the drag-reducing polymer additives. The enstrophy and the strain fields in the FHIT of the polymer solution were remarkably weakened as compared with their Newtonian counterparts. The small-scale vortices and the small-scale intermittency were all inhibited by the viscoelastic effects in the FHIT of the polymer solution. However, the scaling law in a fashion of extended self-similarity for the FHIT of the polymer solution, within the presently simulated range of Weissenberg numbers, had no distinct differences compared with that of the Newtonian fluid case. [ABSTRACT FROM AUTHOR]

MALDI-TOF MS is used for the qualitative analysis of seven different polymer additives directly from the polymer without tedious sample pretreatment. Additionally, by using a solid sample preparation technique, which avoids the concentration gradient problems known to occur with dried droplets and by adding tetraphenylporphyrine as an internal standard to the matrix, it is possible to perform quantitative analysis of additives directly from the polymer sample. Calibration curves for Tinuvin 770, Tinuvin 622, Irganox 1024, Irganox 1010, Irgafos 168, and Chimassorb 944 are presented, showing coefficients of determination between 0.911 and 0.990. [ABSTRACT FROM AUTHOR]

Abstract: Four triazene derivatives have been synthesized, i.e. bis-4,4′-(3,3′-dimethyltriazene)-diphenyl ether (1), bis-4,4′-(3,3′-diethyltriazene)-diphenyl ether (2), 2,2,6,6,-tetramethyl-1-phenylazo-piperidine (3) and 4-hydroxy-2,2,6,6-tetramethyl-1-phenylazopiperidine (4). Their thermal properties were determined by differential scanning calorimetry (DSC) and the fragmentation patterns were analysed by simultaneous mass spectrometry (MS) and Fourier transform infrared (FTIR) spectrometry of off-gases from a thermogravimetric analyser (TGA). The triazenes exhibited an exothermic decomposition peak at temperatures between 230 and 280 °C when the triazene units were homolytically cleaved into various aminyl, resonance-stabilized aryl radicals and different CH fragments with simultaneous evolution of elemental nitrogen. The potential of triazenes as a new class of flame retardants for polypropylene films was investigated by performing ignitability test in accordance to DIN 4102-1/B2 standard. Polypropylene samples containing very low concentration of only 0.5 wt% of any of these triazene (R–N1 = N2–N3R’R″) additives passed the test with B2 classification. Notably, no burning dripping could be detected. The average burning times are very short with exceptionally low weight losses. Based on this preliminary FR testing we have shown that the triazene compounds constitute a new and interesting family of radical generators for flame retarding of polymeric materials. [Copyright &y& Elsevier]

fast and simple method for the direct qualitative and semi-quantitative determination of a set of four polymer additives in plastic samples by desorption electrospray ionization time-of-flight mass spectrometry (DESI-TOF-MS) is presented. After evaluation of crucial DESI parameters such as composition of spray solutions and spray voltages, a series of lab-made polypropylene samples containing Chimassorb 81 (2-hydroxy-4- n-octoxybenzophenone), Tinuvin 328 (2-(2-hydroxy-3, 5- ditert-pentylphenyl)-benzotriazole), Tinuvin 326 (2-(2-hydroxy-3- tert-butyl-5-methylphenyl)-5-chloro benzotriazole), and Tinuvin 770 (bis(2,2,6,6,-tetramethyl-4-piperidyl)sebaceate) in concentrations between 0.02% and 0.2% were analyzed, resulting in calibration graphs with R better than 0.994. To demonstrate the applicability of the developed method for the investigation of real samples, liners for in-ground swimming pools and polypropylene granules were analyzed with respect to their content in the selected polymer additives. Two alternative methods, both well established in the fields of polymer additive analysis, namely HPLC with UV detection (after previous extraction) and thermodesorption gas chromatography/mass spectrometry have been employed for evaluation of the results from the DESI experiments. [ABSTRACT FROM AUTHOR]

Abstract: Polysulfone-based amphiphilic polymer polysulfone-graft-poly (ethylene glycol) methyl ether methacrylate (PSf-g-POEM) was synthesized and used to blend with polyethersulfone (PES) to tune the hydrophobicity and fouling-liable properties of PES membranes. Differential scanning calorimetry (DSC), contact angle measurements, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) were conducted to characterize the properties of blend membranes. DSC results showed that the blend samples were characterized with single T g transition, indicating that the additives were compatible well with PES in membranes. Membranes hydrophilicity was evaluated by contact angle measurement and obviously enhanced wettability of blend membranes was found. XPS analysis suggested that poly (ethylene glycol) methyl ether methacrylate (POEM) brushes from amphiphilic additives occupied half part of the membrane surface composition, and the high content of POEM in surface had effectively improved the membranes hydrophilicity as well as the fouling-resistance to proteins. Meanwhile, the formation of cake layer was explored as a main reason for membrane fouling behavior, while the irreversible filtration resistance (R ir ) could be greatly reduced by incorporation of the synthesized amphiphilic additives. SEM was also conducted to inspect the morphologies of blend membranes. [ABSTRACT FROM AUTHOR]

Influence of 87 C polymer with hydrophilic properties on 3 years replanted hydroponic oak saplings' sticking and growth abilities in Dilijan forest waterless area was studied. It turned out, that 87 C polymer addition on the root - inhabited zone of soil for the saplings (30g/plant) ensured 92 % sticking ability and 16 cm average annual growth of oak saplings during the replanting. [ABSTRACT FROM AUTHOR]

Abstract: The miscibility of styrene-hydrogenated butadiene copolymer (SHB) with different constituents of polymer additives for lubricating mineral oils was studied in dilute solution regime, using xylene as model solvent, at 30°C, in a wide range of polymer blend compositions. The systems studied were SHB/poly(ethylene-co-propylene) (EPC), SHB/poly(methyl methacrylate) (PMMA), SHB/poly(dodecyl methacrylate) (PDDMA) and SHB/polystyrene (PS). The viscometric interaction parameters were calculated according to the Krigbaum–Wall and Catsiff–Hewett models of ideal viscometric behavior. Strong repulsive interactions were found in SHB/PMMA and SHB/PDDMA systems pointing to immiscibility. SHB/EPC and SHB/PS deviated much less from ideality. The results were compared to the theoretical estimation of interaction in polymer blends in the absence of solvent, using the Coleman–Graf–Painter approach. No correlation was observed between the interaction in the bulk and in solution. [Copyright &y& Elsevier]

Abstract: The extraction of antioxidant additives, such as, Irganox 1076 and Irgafos 168, from low-density polyethylene (LDPE) and Irganox 1010 and Irgafos 168 from high-density polyethylene (HDPE) was carried out by supercritical fluid extraction (SFE) working in constant pressure, conventional reflux, and automatic Soxhlet system (Soxtec). Recoveries and repeatability of the evaluated methods, using LDPE and HDPE reference materials, showed some differences between them, but more significant differences were found with features such as sample-processing and time required, which are both crucial for the exploitation of these techniques for quantification in routine industrial quality analysis for additives. SFE was found to be the most advantageous technique in terms of simplicity, cost-effectiveness and speed in comparison to conventional reflux and Soxtec procedures. [Copyright &y& Elsevier]

Abstract: A method for the determination of polymer additives like antioxidants, UV absorbers and processing stabilizers using liquid chromatography (LC) coupled with atmospheric pressure photoionization mass spectrometry (APPI–MS) is presented. Ion source parameters were optimized regarding temperatures, gas flow rates, and voltages applied. Detection limits were determined using APPI with or without dopant and were compared with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). Differences between APPI, ESI and APCI are pointed out and the effect of the dopant toluene and acetone is discussed. The optimized method yielded detection limits between 0.001 mg L−1 and 0.022 mg L−1 for 15 different analytes. Linear calibration plots could be obtained for all solutes over a wide concentration range showing satisfying repeatability with standard deviations of peak areas between 3.4% and 7.6%. The results indicate that the developed method can be regarded as suitable for the quantitative determination of polymer additives even at low concentration levels. [Copyright &y& Elsevier]

Abstract: This study investigated the efficiency of 22 polymer additives of defined and controlled structural characteristics in improving the flow properties of crude oil. The additives were synthesized by the solution polymerization of alkyl acrylates of various alkyl chain lengths with styrene, acrylic acid and 1-vinyl-2-pyrrolidone as copolymers or terpolymers. Polymerization was performed by tert-butylperoxy-2-ethylhexanoate as initiator in xylene at 92°C, up to high conversion. The influence of polymerization conditions on additive composition and properties, and their effect on the pour point and rheological properties of crude oil samples from the fields of Števkovica, Obod and Đeletovci located in the northern Croatia were studied. Additive efficiency was dominantly influenced by the alkyl acrylate chain length. The influence of component with carboxyl functional group or heterocyclic-nitrogen compound on additive quality was less obvious. Additive efficiency significantly depended on the properties of crude oil, and n-paraffin content and distribution. The main advantage of the process is that additives can be directly used without purification. [Copyright &y& Elsevier]

The present work describes preparation of acid resistant composites from porphyrite and wollastonite by adding wastes of furfurol (PA1) and furfuryl alcohol (PA2) production as the polymer additives. The effects of waste polymer additives on the compressive strength, chemical resistance and adhesive ability of the composites were examined. The mechanism of the hydration process and phase evaluation of the composites were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), differential thermal analysis (DTA) and IR spectroscopy. The results indicated that hardening of the composites promoted formation of chemical bond between constituents and calcium fluoride compounds. Comparative study showed that the porphyrite composite (Sample P-2) with 1% PA1 additive and porphyrite - wollastonite composite (Sample PW-9) with 2% PA2 additive have optimal parameters among the samples. Acid resistance and compressive strength of prepared composites applied to surfaces of metal and ceramic materials were determined and enhanced properties of porphyrite - wollastonite composite with additive PA2 were found to be in metal (2.4 ?P?). The reason for the improvement of the chemical resistance and compressive strength of the composites may be attributed to the formation of the amorphous silicon phase. [ABSTRACT FROM AUTHOR]

This work reports the thermal and structural changes promoted by Buriti ( Mauritia flexuosa L.) oil incorporation into polystyrene (PS) and poly(methyl methacrylate) (PMMA) matrices. Buriti oil, which was used due to its high β-carotene content has a good thermal stability and can provide some stability to PS and PMMA as it was shown by TG and TMA data. DSC results showed that both PMMA and PS-based materials were plasticized by the oil and demonstrated that they are immiscible materials. SEM images depict the materials’ morphology. [ABSTRACT FROM AUTHOR]

Abstract: Polysulfone membranes on a cellulose support were obtained by phase inversion, directly on the carrier''s surface. The membranes were obtained by the continuous method by means of a special device. Cellulose was dissolved in order to study the real membrane thickness and estimate the depth of polymer penetration into the cellulose matrix. Thickness measurements of the membranes were carried out and their high uniformity was found. The permeation times for the membrane alone and for the membrane on a support have been compared. It was found that the sum of times of permeation through a cellulose support and through a membrane deprived of a support is always shorter than that through a membrane and support together. For one thickness assumed as optimal, the dependence of time of permeation through a membrane and support for different compositions of membrane-forming mixtures was studied. The membrane-forming mixture contained always the same concentration of the basic polymer and the same concentration of the pore-precursor additive. Polyvinylpyrrolidones (PVPs) of various molecular weights, both alone and as mixtures of two PVP of different molecular weights, were used as pore-precursors for obtaining these membranes. It was found that the shortest times of permeation through the studied membranes are obtained when equal weigh amounts of PVP of different molecular weights are used as the additive to polysulfones. It was found that the membrane for which an equilibrium PVP mixture of 10 and 60kDa molecular weight was used as the pore-precursor, which is best suitable for dry tests. Such membranes are especially well suitable for obtaining dry tests for the analysis of fruit and vegetable juices. [Copyright &y& Elsevier]

Abstract: Pyrolysis–gas chromatography (Py–GC) has become well established as a simple, quick and reliable analytical technique for a range of applications including the analysis of polymeric materials. Recent developments in Py–GC technology and instrumentation include laser pyrolysis and non-discriminating pyrolysis. Progress has also been made in the detection of low-level polymer additives with the use of novel Py–GC devices. Furthermore, it has been predicted that future advances in separation technology such as the use of comprehensive two-dimensional gas chromatography will further enhance the analytical scope of Py–GC. [Copyright &y& Elsevier]

Abstract: The phenomenon of drag reduction in walled turbulent flows of polymer solutions is theoretically modeled. A new mechanistic model of a polymer molecule in a turbulent flow field is suggested. It is argued that the dominant forces on a polymer fiber in the turbulent flow field are elastic and centrifugal. According to this model, an additional route of dissipation exists, in which eddy kinetic energy is converted to polymer elastic energy by the centrifugal elongation of the rotated polymer, which in turn is viscously damped by the surroundings, when the polymer relaxes. A novel approach is then illustrated, where it is shown that this mechanistic model can be accounted for as a turbulent scale alteration, instead of addition, which enables the classical dimensional analysis of a turbulent boundary layer to apply. Using this dimensional analysis with the equivalent altered scale yields remarkable results. Correct-form velocity profiles are obtained, and Virk''s asymptote and slope are predicted with no empirical constants. Drag–flow rate curves are also calculated, and compared favorably with Virk''s experiments. The onset of drag reduction phenomenon is also explained by this model, and calculations of it are also compared with Virk''s data. The parametric dependencies of the onset point agree well with Virk''s conclusions. [Copyright &y& Elsevier]

Abstract: Undesirable residue formation and lower performance can be observed during the use of polymer-based chemical additives in the petroleum industry when such compounds are mixed during a number of operations, such as oil production. In this work a demulsifier, a flocculant and a scale inhibitor and their respective polymeric bases were tested. These were evaluated through specific performance tests for each additive and a solubility test to assess residue formation. By correlating the performance of commercial additives and the respective polymeric bases, we can conclude that the polymeric base is responsible for the positive synergistic effects on demulsifier performance in the presence of other additives and for the negative synergistic effects on scale-inhibiting performance, also in the presence of other additives. Moreover, we found that the polymeric base can be responsible for the residue formation from the scale inhibitor and flocculant mixture, although it is not be responsible for the residue formation of the flocculant alone. [Copyright &y& Elsevier]

Abstract: On-line coupled size exclusion chromatography–pyrolysis gas chromatography mass spectrometry (SEC–Py-GC–MS) is studied as a novel tool for the characterization of complex polymer samples. An automated system for on-line SEC–Py-GC–MS allowing transfer of multiple fractions was developed based on stop-flow operation of the SEC dimension, syringe-based transfer of the SEC fraction to the GC instrument and solvent elimination with subsequent pyrolysis in a programmed temperature vaporization (PTV) injector. After optimization the system was applied to the characterization of a complex terpolymer composed of very similar monomers. The use of the system for combined pyrolysis and additive analyses in polycarbonate was also demonstrated. Results obtained with the new method indicate the interesting potentials of the method for detailed characterization of polymeric materials. [Copyright &y& Elsevier]

Abstract: The large size of the hyperspectral datasets that are produced with modern mass spectrometric imaging techniques makes it difficult to analyze the results. Unsupervised statistical techniques are needed to extract relevant information from these datasets and reduce the data into a surveyable overview. Multivariate statistics are commonly used for this purpose. Computational power and computer memory limit the resolution at which the datasets can be analyzed with these techniques. We introduce the use of a data format capable of efficiently storing sparse datasets for multivariate analysis. This format is more memory-efficient and therefore it increases the possible resolution together with a decrease of computation time. Three multivariate techniques are compared for both sparse-type data and non-sparse data acquired in two different imaging ToF-SIMS experiments and one LDI-ToF imaging experiment. There is no significant qualitative difference in the use of different data formats for the same multivariate algorithms. All evaluated multivariate techniques could be applied on both SIMS and the LDI imaging datasets. Principal component analysis is shown to be the fastest choice; however a small increase of computation time using a VARIMAX optimization increases the decomposition quality significantly. PARAFAC analysis is shown to be very effective in separating different chemical components but the calculations take a significant amount of time, limiting its use as a routine technique. An effective visualization of the results of the multivariate analysis is as important for the analyst as the computational issues. For this reason, a new technique for visualization is presented, combining both spectral loadings and spatial scores into one three-dimensional view on the complete datacube. [Copyright &y& Elsevier]