polymers

Thermogravimetry and Differential Thermal Analysis (TG-DTA)

Italiano

La TGA-DTA simultanea permette di identificare in modo semi-quantitativo e qualitativo i componenti di una sostanza che in un determinato intervallo di temperatura perde peso e/o assorbe calore. La simultaneità delle due analisi aumenta la possibilità di identificazione. La strumentazione è costituita da una termobilancia che con un sistema di termocoppie permettere di registrare contemporaneamente le perdite di peso dovute a decomposizioni/trasformazioni dei costituenti della sostanza in esame e gli assorbimenti/emissioni di calore caratteristici delle loro trasformazioni.

Hidden gratings in holographic liquid crystal polymer-dispersed liquid crystal films

Dynamic diffraction gratings that are hidden in the field-off state are fabricated utilizing a room-temperature photocurable liquid crystal (LC) monomer and nematic LC (NLC) using holographic photopolymerization techniques. These holographic LC polymer-dispersed LCs (HLCPDLCs) are hidden because of the refractive index matching between the LC polymer and the NLC regions in the as-formed state (no E-field applied).

Thermoplasmonic activated reverse-mode liquid crystal gratings

A new generation of reconfigurable optical components is conceived by bridging the photothermal properties of gold nanoparticles and the thermosensitivity of liquid crystalline materials. As such, gold nanorods (GNRs) heated using light are used to activate efficient hidden diffraction gratings realized in a blend made of a room temperature polymerizable liquid crystal (PLC) and nematic liquid crystal (NLC).

Cycloidal diffractive waveplates fabricated using a high-power diode-pumped solid-state laser operating at 532 nm

Diffractive waveplates (DWs) are highly efficient optical components realized by means of a polarization holography setup that makes use of UV/blue laser sources. It is more convenient to perform the holographic recording process with green lasers (e.g., continuous wave operating at 532 nm) because they offer compactness, efficiency, and high power. Unfortunately, the photo-alignment materials used forDWfabrication exhibit limited sensitivity at 532 nm.

Polymer dispersed liquid crystals

Low molar mass liquid crystals (LCs) are typically not soluble in polymer systems to any great degree. When the two different materials are mixed, this leads to two-phase systems whose morphology depends on a variety of factors including, primarily, the concentration. The resulting two-phase structures can have inclusions with nanometer through macroscopic dimensions. Although there are a large number of variants, these structures are generically called 'polymer dispersed liquid crystals' (PDLCs) when the resulting morphologies lead to systems that scatter light.

Thermoplasmonic-activated hydrogel based dynamic light attenuator

This work describes the morphological, optical, and thermo-optical properties of a temperature-sensitive hydrogel poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) [P(NIPAm-co-NIPMAm]) film containing a specific amount of gold nanorods (GNRs). The light-induced thermoplasmonic heating of GNRs is used to control the optical scattering of an initially transparent hydrogel film. A hydrated P(NIPAm-co-NIPMAm) film is optically clear at room temperature.

The alpha-1 antitrypsin polymer load correlates with hepatocyte senescence, fibrosis stage and liver-related mortality

Background: Alpha-1 antitrypsin deficiency (AATD) is an important, inherited cause of chronic liver disease. Marked variation in fibrosis stages in patients with homozygous deficiency and those factors that determine whether heterozygous carriers develop liver fibrosis, remain unexplained. Murine studies implicate polymerized alpha-1 antitrypsin (AAT) within hepatocytes as pathogenic.

Hyperspectral imaging for VIS-SWIR classification of post-consumer plastic packaging products by polymer and color

An efficient and reliable post-consumer plastic packaging recovery represents one of the main targets of the sector in a circular economy perspective. Secondary plastics are still far to reach in EU important volumes in respect of primary ones, this is due to: i) the similar physical-chemical characteristics utilized to perform separation and ii) the transfer/collection methods. In this paper the results, referred to polyethylene (PE) and polypropylene (PP), achieved adopting a combined hyperspectral imaging-based approach in the VIS-SWIR ranges are reported.

The canonical behavior of the entropic component of thermodynamic effective molarity. An attempt at unifying covalent and noncovalent cyclizations

This review article is concerned with the measurement, significance and applications of the concept of effective molarity (EM) in a large variety of cyclization reactions ranging from the formation of giant macromolecules in polymeric equilibrates to the self-assembly of cyclic supermolecules and supramolecular aggregates.

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