A polymer network based on thermoplastic polyurethane and ethylene–propylene–diene elastomer via melt blending: morphology, mechanical properties, and rheology

Study on blends of thermoplastic polyurethane and aliphatic polyester: morphology, rheology, and properties as moisture vapor permeable films

The blends of poly(methyl methacrlate) (PMMA) and thermoplastic polyurethane (TPU) were prepared by a Brabender co-twin screw extruder. The mechanical and three-body abrasive wear behaviour of PMMA/TPU blends has been studied. Three-body abrasive wear tests were conducted using rubber wheel abrasion tester (RWAT) under different abrading distances at 200 rpm and 22 N load. A significant reduction in tensile strength and tensile modulus with an increase in TPU content in the blend formulation was observed. Three-body abrasive wear results indicate that the wear volume increases with increase in abrading distance for all the samples studied. However, neat PMMA showed better wear resistance as compared to PMMA/TPU blends. The worn surface features, as examined through scanning electron microscope (SEM), show matrix cracking and deep furrows in PMMA/TPU blends.

Mechanical and three-body abrasive wear behaviour of PMMA/TPU blends

The state-of-the-art characterization technique for the bulk morphology of technical multiphase polymer systems is currently transmission electron microscopy (TEM). With the development of numerous dynamic measuring modes, atomic force microscopy (AFM) is now also capable of mapping multiphase polymer systems with extremely high resolution and material contrast. Nevertheless, the vast majority of the latter work has been conducted on thin-film model systems, in most cases cast or spin-coated from solution. For most industrial applications of polymer systems, however, the bulk morphology is of primary interest In the present paper, surface preparation techniques (microtoming, press moulding and partial dissolution) for AFM investigation of the bulk morphology of technical polymer systems are discussed and AFM results-in most cases tapping mode images with phase detection-are compared systematically with TEM data. Atomic force microscopy is not only capable of accessing simple phase distributions, as in the ABS blend, but it can also give insight into more complex inner particle structures as in certain types of ASA or PP blends. Compatibilizer distributions can be mapped too. In all these cases, TEM and AFM results are in line with each other, in some cases complimentary. Tapping mode phase-contrast mapping together with classical cryomicrotoming yielded the best results with most of the polymers in the study. Press moulding or partial dissolution, although simpler, yielded only partial information on the morphology of the systems.

Determination of the bulk structure of technical multiphase polymer systems with AFM: comparative AFM and TEM investigation

https://doi.org/10.1016/j.coesh.2022.100396

An opinion on Wastewater-Based Epidemiological Monitoring (WBEM) with Clinical Diagnostic Test (CDT) for detecting high-prevalence areas of community COVID-19 Infections

A wastewater-based epidemiology tool for COVID-19 surveillance in Portugal

An etching technique for morphological investigation of TPU/ABS blends by SEM

Shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the feces and urine of infected patients and subsequent presence in wastewater has produced interest on the use of this matrix for sentinel surveillance at a community level and as a complementary approach to syndromic surveillance. With this work, we set the foundations for wastewater-based epidemiology (WBE) in Portugal by monitoring the trends of SARS-CoV-2 RNA circulation in the community, on a nationwide perspective during different epidemiological phases of the pandemic. The Charite assays (E_Sarbecco, RdRP, and N_Sarbecco) were applied to monitor, over 32-weeks (April to December 2020), the dynamics of SARS-CoV-2 RNA at the inlet of five wastewater treatment plants (WWTP), which together serve more than two million people in Portugal. Raw wastewater from three COVID-19 reference hospitals was also analyzed during this period. In total, more than 600 samples were tested. Sampling started late April 2020, during lockdown, and, for the first weeks, detection of SARS-CoV-2 RNA was sporadic, with concentrations varying from 103 to 105 genome copies per liter (GC/L). Prevalence of SARS-CoV-2 RNA increased steeply by the end of May into late June, mainly in Lisboa e Vale do Tejo region (LVT), during the reopening phase. After the summer, with the reopening of schools in mid-September and return to partial face-to-face work, a pronounced increase of SARS-CoV-2 RNA in wastewater was detected. In the LVT area, SARS-CoV-2 RNA load agreed with reported trends in hotspots of infection. Synchrony between trends of SARS-CoV-2 RNA in raw wastewater and daily new COVID-19 cases highlights the value of WBE as a surveillance tool for this virus, particularly after the phasing out of the epidemiological curve and when hotspots of disease re-emerge in the population which might be difficult to spot based solely on syndromic surveillance and contact tracing.

/pdf/a-wastewater-based-epidemiology-tool-for-covid-19-1ie60iy5q8.pdf

A Wastewater-based Epidemiology tool for COVID-19 Surveillance in Portugal

Wastewater-based epidemiology (WBE) for severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) is a powerful tool to complement syndromic surveillance: first, as an early-warning system for the spread of the virus in the community, second, to find hotspots of infection, and third, to aid in the early detection and follow-up of circulating virus variants. Although detection of SARS-CoV-2 in raw wastewater may be prompted with good recoveries during periods of high community prevalence, in the early stages of population outbreaks concentration procedures are required to overcome low viral concentrations. Several methods have become available for the recovery of SARS-CoV-2 from raw wastewater, generally involving filtration. However, these methods are limited to small sample volumes, possibly missing the early stages of virus circulation, and restrained applicability across different water matrices. The aim of this study was thus to evaluate the performance of three methods enabling the concentration of SARS-CoV-2 from large volumes of wastewater: i) hollow fiber filtration using the inuvai R180, with an enhanced elution protocol and polyethylene glycol (PEG) precipitation; ii) PEG precipitation; and iii) skimmed milk flocculation. The performance of the three approaches was evaluated in wastewater from multiple wastewater treatment plants (WWTP) with distinct singularities, according to: i) effective volume; ii) percentage of recovery; iii) extraction efficiency; iv) inhibitory effect; and v) the limits of detection and quantification (The inuvai R180 system had the best performance, with detection of spiked controls across all samples, average recovery percentages of 64% for SARS-CoV-2 control and 68% for porcine epidemic diarrhea virus (PEDV), with low variability. The inuvai R180 enables the scalability of volumes without negative impact on the costs, time for analysis, and recovery/inhibition. Moreover, hollow fiber filters favor the concentration of different microbial taxonomic groups. Such combined features make this technology attractive for usage in environmental waters monitoring.

/pdf/concentration-of-sars-cov-2-from-large-volumes-of-raw-1vra5nk8h3.pdf

Marco Silva

Papers

A wastewater-based epidemiology tool for COVID-19 surveillance in Portugal

An etching technique for morphological investigation of TPU/ABS blends by SEM

A Wastewater-based Epidemiology tool for COVID-19 Surveillance in Portugal

Concentration of SARS-CoV-2 from large volumes of raw wastewater is enhanced with the inuvai R180 system