Search results for "SLI"

Photo-crosslinking in freely-suspended films of ferroelectric lc-polymers

1995

X-ray topographic study of solid-state polymerized poly-[1,2-bis-(p tolylsulphonyloxymethylene)-1-butene-3-inylene]

1976

Local extinction contrast effects have been observed in macroscopic polymer crystals, using Berg-Barrett X-ray topography. Results from as-polymerized crystals indicate that the crystals are perfect enough for defect regions to be imaged. As-polymerized crystals exhibited apparent defects lying along [021]. [010] slip traces in the (100) surface of a crystal were imaged; the slip system here appears to be consistent with (h01) [¯10h], forh, l ≠ 0 and [010] the chain direction.

Effect of an organoclay on the photochemical transformations of a PBAT/PLA blend and morpho-chemical features of crosslinked networks

2021

Abstract In this work, we report the effect of an organoclay on the photochemical weathering of nanocomposites based on a poly(butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) blend. The evolution of physicochemical properties was monitored by integrating spectroscopic, mechanical, and morphological analyses. A robust relationship was found between the molecular transformations of the polymer macromolecules and the morpho-mechanical properties of irradiated films. Moreover, the analysis of insoluble fractions extracted from nanocomposites pointed out that free-standing, porous structures, displaying an unprecedented thickness as great as 100 µm, were formed, thus unambiguou…

Confinement-induced screening of hydrodynamic interactions and spinodal decomposition: Multiscale simulations of colloid-polymer mixtures

2012

Phase separation kinetics of a colloid-polymer mixture confined between two planar repulsive walls is studied by a multiscale simulation approach. Colloids and polymers are described by particles interacting with continuous potentials suitable for molecular-dynamics simulation, while hydrodynamic interactions mediated by solvent particles are accounted for by the multiparticle collision dynamics method. Varying the distance D between the walls and the character of the boundary conditions, the interplay of structure formation parallel and perpendicular to the walls is studied, and the effect of hydrodynamics on the growth of domain size ld(t) with time t is elucidated. Only for slip boundary…

Photoaffinity cross-linking of F1ATPase from the thermophilic bacterium PS3 by 3′-arylazido-β-alanyl-2-azido ATP

1989

AbstractThe photoactivatable bifunctional 3′-arylazido-β-alanyl-2-azido ATP (2,3′-DiN3ATP) has been applied to study the localization of the nucleotide-binding sites of coupling factor 1 (F1ATPase, TF1) from the thermophilic bacterium PS3 by photoaffinity cross-linking. UV irradiation of TF1 in the presence of 2,3′-DiN3ATP results in the nucleotide-dependent formation of various higher molecular mass cross-links formed by two, three or even four α- and/or β-subunits. The differences observed upon photoaffinity cross-linking by the bifunctional 2-azido ATP or 8-azido ATP analog are discussed. They are probably due to the varied maximal distance between both azido groups, or to the different …

Anisotropic Stick-slip friction of highly oriented thin films of poly(tetrafluoroethylene) at the molecular level

1996

Lateral force microscopy (LFM) studies of poly(tetrafluoroethylene) (PTFE) films with molecular resolution are reported. Thin PTFE layers with a high degree of orientation were obtained by pressing and sliding a block of polymer on a clean, heated muscovite mica substrate. LFM nanographs obtained on these films by scanning at directions between ca. 40 and 90° with respect to the film orientation direction, i.e. with respect to the direction of the polymer chains, showed a “stick-slip” type frictional motion of the LFM probe tip at the molecular level. The friction force observed at constant load decreased with decreasing scan angles. Chain-chain packing distances obtained by LFM and contact…

Hydrodynamic mechanisms of spinodal decomposition in confined colloid-polymer mixtures: A multiparticle collision dynamics study

2013

A multiscale model for a colloid-polymer mixture is developed. The colloids are described as point particles interacting with each other and with the polymers with strongly repulsive potentials, while polymers interact with each other with a softer potential. The fluid in the suspension is taken into account by the multiparticle collision dynamics method (MPC). Considering a slit geometry where the suspension is confined between parallel repulsive walls, different possibilities for the hydrodynamic boundary conditions (b.c.) at the walls (slip versus stick) are treated. Quenching experiments are considered, where the system volume is suddenly reduced (keeping the density of the solvent flui…

Analysis of the metabolic switch induced by the spirulina peptide SP6 in high fat diet ApoE-/-mice model: A direct infusion FT-ICR-MS based approach

2021

Atherosclerosis, dyslipidemia and hypertension are comorbid diseases often found in combination. Among different pharmacological approaches the employment of natural multifunctional peptides is an attractive option as side therapy. Mass spectrometry-based metabolomics provide valuable information on metabolic changes and can be useful to elucidate peptide pharmacodynamics. In this this work we performed a preliminary investigation on the potential effect of a recently characterized Spirulina platensis peptide named SP6 (GIVAGDVTPI) on the modulation of metabolism in a high fat diet ApoE-/- mice atherosclerotic model. A direct infusion Fourier transform ion cyclotron resonance mass spectrome…

Die Darstellung von Gelen als stationäre Phase für die Gelchromatographie

1970

Bei vernetzten Copolymeren aus athylvinylbenzol/Divinylbenzol sowie Vinylacetat/Divinyladipat wird der Einflus der Herstellungsbedingungen auf die Eigenschaften der vernetzten Polymeren untersucht. Homogen-vernetzte Gele eignen sich vor allem zur Trennung von Oligomeren; mit heterogen-vernetzten Gelen konnen Polymere getrennt werden. Es wird gezeigt, das bei der heterogen-vernetzenden Polymerisation die Heterogenitat der Copolymeren mit sinkendem Solvatationsvermogen der Inertkomponente wachst; dies fuhrt gleichzeitig zu einer Erhohung des Aussechlusmolekulargewichtes. The influence of the mode of synthesis on the characteristics of crosslinked polymers is examined for crosslinked copolymer…

Control of end-of-life oxygen-containing groups accumulation in biopolyesters through introduction of crosslinked polysaccharide particles

2021

The formulation of bio-based materials with good performance in service and controlled end-of-life is imperative for an effective circular economy. In this work, an innovative approach to induce and control the end-of-life of biodegradable polyesters through introduction of crosslinked polysaccharide particles is proposed. Chitosan (Ch) has been subjected to ionotropically crosslinking and then added to polylactic acid (PLA) at different amounts (1.0–4.0%w) by melt mixing. All obtained results suggest that the addition of crosslinked Ch (cCh) particles does not modify significantly the investigated biopolyester properties. Specifically, the thermal analysis of the composites reveals that th…