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•PVC-diphenylamine modified cellulose was proposed as sorptive phase.•The synthesis, using the dip-coating technique, is simple and cost-effective.•Opioids interact with the membrane ...by a mixed-mode interaction.•Direct infusion mass spectrometry allows to reduce the time of analysis.•The approach was successfully applied to real saliva samples containing codeine and tramadol.
This article evaluates the potential of cellulose paper as a substrate for preparing a polyvinylchloride (PVC)-diphenylamine sorptive phase that can be used under the thin film microextraction (TFME) format. This phase was easily synthesized using the dip-coating technique to coat the filter paper with PVC, followed by the covalent bonding of diphenylamine. As a result, aromatics rings are available on paper surface to isolate the target analytes by a mixed-mode interaction at physiological pH. The resulting material was characterized by infrared spectroscopy, UV–Vis diffuse reflection spectroscopy, and scanning electron microscopy. As analytical problem, three opioids (methadone, codeine, and tramadol) were determined in saliva samples by direct infusion mass spectrometry. Different variables involved in the extraction procedure have been optimized (e.g. sample pH, extraction time, and sample dilution). The proposed method provides good linearity (R2 > 0.9817) and sensitivity (detection limits in the range from 1.5 µg L−1 to 15 µg L−1). The intra-day and inter-day precision, expressed as relative standard deviation, were better than 16.4 % and 18.5 % respectively. The accuracy, expressed as relative recovery, provides values in the interval from 82 % to 105 %. Finally, the proposed approach has been successfully applied to real saliva samples of patients under codeine and tramadol medical prescription.
In this study, the interaction of emerging pollutant polyvinyl chloride microplastics (PVC MPs) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV–visible (UV–vis) ...absorption spectroscopy, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy under simulated physiological conditions. Fluorescence results showed that PVC MPs (about 5000 nm in size) can effectively quench the intrinsic fluorescence of HSA through static quenching owing to the formation of HSA-PVC complex. The binding constants (Ka) between PVC and HSA at different temperatures were calculated as 4.97 × 103 M−1, 3.46 × 103 M−1 and 2.51 × 103 M−1, respectively. The number of binding sites was 1.26. The enthalpy change (ΔH), entropy change (ΔS) and free energy change (ΔG) were calculated to be −59.27 kJ·mol−1, 70.76 J·mol−1 K−1 and − 80.35 kJ·mol−1, respectively, indicating that the interaction of PVC with HSA was mainly driven by electrostatic forces. Moreover, results of UV–vis, FT-IR and CD further demonstrated that the microenvironment and secondary structure of HSA were changed a lot induced by PVC, leading to a decrease in α-helix. This work not only provides an insight into the intermolecular interaction between PVC and HSA, but also elucidates the potential biological toxicity of MPs at a molecular level.
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•Multispectroscopic techniques were employed to reveal the potential toxicity effect of MPs to biomacromolecules at the molecular level.•The fluorescence of HSA was quenched by PVC MPs through a static quenching.•Electrostatic interactions played a predominant role in the formation of PVC-HSA complex.•The secondary structure of HSA underwent a decrease in α-helix induced by PVC MPs.•The backbone of HSA experienced a microenvironmental alteration.
Various chemical substances, such as potentially toxic trace metals, are used as plastic additives to improve the performance of polymers and extend the service life of plastic products. However, ...these added trace metals are likely released from plastic into the environment when the plastic becomes a pollutant, although the process is poorly understood. In this study, chemical ageing of commercial polyvinyl chloride (PVC) microplastics using hydrogen peroxide (H2O2) and natural ageing of PVC that had been added to an alkaline paddy soil were undertaken to evaluate the potential release of trace metals from PVC. Enhanced release of trace metals from PVC with the increasing H2O2 concentrations was observed, in which the released Pb was 1–2 orders of magnitude higher than other metals (p < 0.01). The released Cr, Ni, Pb, Cu, Zn, Cd and Mn accounted for 87.37%, 79.27%, 22.02%, 20.93%, 17.06%, 15.11%, and 11.02% of their total concentrations (0.28 ± 0.03, 0.08 ± 0.01, 13.67 ± 0.18, 1.07 ± 0.02, 2.20 ± 0.18, 0.05 ± 0.00 and 1.26 ± 0.08 mmol kg−1) in PVC after ageing with 30% H2O2, respectively. Compared with the control treatment without PVC addition, the concentrations of CaCl2-extractable Cu, Mn, Ni, Pb, and Zn in the soil treated with 5% PVC are significantly increased after incubation for 60 days (p < 0.01). In conclusion, chemical and natural ageing have the potential to lead to the release of Cu, Mn, Ni, Pb, and Zn from the commercial PVC into aquatic and terrestrial environments.
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•Potential release of metal additives within commercial PVC was examined.•Both chemical (H2O2) and natural (soil incubation) ageing were considered.•Ageing processes caused the metal release from PVC to the environment.•Metal-loaded PVC addition increased the alkaline soil metal bioavailability.
•NBR/PVC blends were the main variety of rubber-plastic mixtures.•The challenges to recycling the cross-linked foams are insoluble and infusible.•The powder with high thermal stability and degree of ...reclaiming was obtained.•Intermolecular interactions limited the mobility of chains of reclaimed powder.
Cross-linked acrylonitrile-butadiene rubber (NBR)/poly(vinyl chloride) (PVC) blends are extensively served as commercial insulation foams. However, methods to reclaim the wasted NBR/PVC composites are usually inappropriate, causing severe pollution. Herein, we reported that the waste NBR/PVC composites powders (WNPP) with high thermal stability and degree of reclaiming were prepared by solid-state shear milling technology (S3M). Furthermore, the reclaimed products via thermoplastic re-processing had excellent mechanical properties, and the optimal stress and strain were increased by 208.2 % and 269.4 %, respectively, compared with the products made from virgin scraps. Through the investigation of each sample's molecular chains and thermal properties, it was found that when the cross-linked polar rubber-plastic composites are reclaimed, the molecular chains of the rubber phase would be close to each other. The interaction among polar groups would be enhanced, which is the main contributing factor limiting the movability of the polymer chains. And the interaction between the polar rubber and plastic phases would also increase, which is beneficial for the compatibility of the two phases. Moreover, there is a phase separation between the de-crosslinked continuous phase and the residual cross-linked network region for the re-processing products.
A bio-based Mg(OH)2@tin phytate@zinc tannate (MH@PASn@TAZn) composite was synthesised via layer-by-layer assembly method. Chemical bonds formed by chelating metal ions with phytic acid and tannic ...acid were involved in this synthesis. MH@PASn@TAZn was then incorporated into PVC and its effects on flame retardancy, smoke suppression and mechanical properties were investigated. The core-shell structure and binding states between each layer (Mg–O–P, P–O–C) of the composite were examined. The limiting oxygen index (LOI) and cone calorimeter test results showed that the addition of 10 ph MH@PASn@TAZn effectively enhanced the flame retardancy and smoke suppression of PVC. The LOI value of the 10 ph MH@PASn@TAZn-incorporated PVC sample increased to 30.3% because of the combination of the gas dilution effect of vapor generated by the degradation of MH and synergistic catalytic carbonisation of PASn and TAZn. The second peak heat release rate, second peak smoke production rate and total smoke production of PVC/MH@PASn@TAZn composite decreased by 40.8%, 72.2% and 35.2%, respectively. The increase in the interfacial contact area of PASn and the enhancement of interfacial interaction of TAZn significantly improved the tensile strength, elongation at break, and impact strength of PVC. This study presents a promising approach to synthesise flame-retardant PVC with excellent smoke suppression and mechanical properties.
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•A novel bio-based MH@PASn@TAZn was designed via layer-by-layer assembling technique and incorporated into flexible PVC.•The core-shell structure and binding states between each layer (Mg–O–P, P–O–C) was characterized and confirmed.•The flame retardancy and smoke suppression of the composites were improved dramatically by the synergistic action.•The mechanical property was significantly improved with assistance of assembly layer.
•Polymer Nanocomposite’s image analysis for qualitative and quantities analysis of nanofillers dispersion.•Proposing a framework to find the global threshold value for analysis of level of dispersion ...of TiO2 Nanofillers.•Conversion of PVC/TiO2 SEM images into Segmental map and Dispersion map through proposed algorithm.•Correlation of the proposed image analysis framework with tensile properties offered by PVC/TiO2 nanocomposites.
The present paper deals with image analysis of Scanning Electron Microscope (SEM) micrographs of PVC / TiO2 nanocomposites prepared through solution casting technique at different wt% of TiO2 nanofillers dispersed within the PVC matrix. The qualitative and quantitative dispersion of TiO2 nanofillers is estimated through the proposed algorithm based on global threshold obtained from Otsu’s method. The PVC-TiO2- PVC molecular region map and TiO2 nanofillers dispersion maps are obtained by background elimination technique with predefined threshold value and a global threshold value, respectively. The particle size distribution histograms are obtained in terms of TiO2 nanofillers population versus available PVC/TiO2 matrix areal spread. This study is carried out to correlate qualitative and quantitative dispersion of TiO2 nanofillers within the PVC matrix with the variation of specimen properties accordingly.
Low cost massive wastes, wood flour (WF) and precipitated calcium carbonate (PCC-sugar origin(were used as fillers completely incorporated in polyvinyl chloride (PVC) matrix producing PVC/WF/PCC ...composites of lower density and cost with higher thermal stability and stiffness compared with PVC. Some hydrogen bonds formed between OH of lignin and cellulose in WF and α-H of PVC by incorporating of WF into PVC matrix. Tensile modulus of composites increased by adding both PCC and/or WF into PVC matrix which is probably due to restraining effect of filler on polymer molecules. Hardness Shore-D increased with increasing both WF and PCC of higher hardness than PVC matrix. Tensile and flexural strength of PVC/WF composite improved by adding low content of PCC that having good dispersion of PCC particles in PVC matrix (up to 10 wt.%) compared with the composite contains 62 wt.% WF. At higher wt.%, tensile and flexural strength are reduced due to the absence of uniform distribution of PCC in PVC/WF matrix which improves the mechanical properties. SEM images showed the morphology and possible interfacial adhesion within the composite. SEM micrograph for neat PVC compound showed homogeneous, smooth and uniform fractured surface while SEM micrograph for PVC/62 wt.% WF showed many voids indicating poor PVC-WF interaction. Some particles pulled out or remained loosely within the matrix resulting in poor stress transferring from matrix to the filler. SEM micrograph of PVC/52 wt.% WF/10wt.% PCC composite showed the best dispersion of PCC in PVC/WF matrix. Dispersion became non- homogeneous at the percentages higher than 10 wt.% due to the agglomeration of PCC particles leading to cavities in the matrix. The lower filler content leads to more uniform dispersion of PCC particles inside the matrix. H2O absorption and thickness swelling of PVC/WF/PCC composites were higher than PVC due to WF polarity. PCC enhanced thermal stability of composites and act as an acid acceptor for secondary stabilization of PVC neutralizing chloride ions.
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