Search results for "force"

Prediction method of electrical conductivity of nano-modified glass fibre reinforced plastics

2019

Glass fibre reinforced plastics (GFRP) is non-conductive construction material, however with carbon nanotubes (CNT) modifying it can get additional functionality due to its gained electrical conductivity. Main aim of the study is to check functionality of the prediction method of electrical conductivity of GFRP with nano-modified epoxy matrix using structural approach. GFRP composites under investigation were based on unidirectional (UD) Glass fiber and two matrixes modified with carbon nanotubes. Electrical conductivity of epoxy resin modified by CNT (concentrations < 1%) was modelled using structural approach. Electrical conductivity of unidirectional GFRP layer was measured experimentall…

Graphene related magnetic materials: micromechanical exfoliation of 2D layered magnets based on bimetallic anilate complexes with inserted [FeIII(aca…

2015

The syntheses, structures and magnetic properties of the coordination compounds of formula [FeIII(acac2-trien)][MnIICrIII(Cl2 An)3]·(CH3CN)2 (1), [FeIII(acac2-trien)][MnIICrIII(Br2An)3]·(CH3CN)2 (2) and [GaIII(acac2-trien)][MnIICrIII(Br2An)3]·(CH3CN)2 (3) are reported. They exhibit a 2D anionic network formed by Mn(II) and Cr(III) ions linked through anilate ligands, while the [FeIII(acac2-trien)]+ or [GaIII(acac2-trien)]+ charge-compensating cations are placed inside the hexagonal channels of the 2D network, instead of being inserted in the interlamellar spacing. Thus, these crystals are formed by hybrid layers assembled through van der Waals interactions. The magnetic properties indicate …

Structure Formation of Polymeric Building Blocks: Complex Polymer Architectures

2013

This chapter describes macromolecules with a complex structure, their defined aggregation in solution, their adsorption to surfaces, and their possible aggregation on surfaces. The term “complex structure” implies that the macromolecules show different, distinct structural elements or building blocks on a supra-atomic length scale. Key to understanding the complex structure of macromolecules, their aggregation, and adsorption to surfaces are intra- and intermolecular interactions such as van der Waals, electrostatic, π–π interactions, and hydrogen bonds.

Photoconductivity of Poly(Arylenevinylene)S and Poly(Hetarylenevinylene)S

1994

Abstract The intramolecular condensation of aromatic Schiff bases leads under strong alkaline conditions to the poly(arylenevinylene)s and poly(hetarylenevi-nylene)s A - H. Due to the extreme stereoselectivity the resulting products are rigid, (E)-configurated polymers. The broad band gap of the unsubstituted intrinsic insulators is decreased by alkoxy substituents. Investigations of the photoconductivity and the photoreactivity, as well as of the AC-conductivity of some undoped, doped and quaternized systems are performed.

2018

Star-shaped polymers show a continuous change of properties from flexible linear chains to soft colloids, as the number of arms is increased. To investigate the effect of macromolecular architecture on the flow properties, we employ computer simulations of single chain and star polymers as well as of their mixtures under Poiseuille flow. Hydrodynamic interactions are incorporated through the multi-particle collision dynamics (MPCD) technique, while a bead-spring model is used to describe the polymers. For the ultradilute systems at rest, the polymers are distributed uniformly in the slit channel, with a weak dependence on their number of arms. Once flow is applied, however, we find that the…

The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators

2019

This research was supported by the European Regional Development Fund within the project ‘‘Hybrid energy harvesting systems’’ 1.1.1.1./16/A/013.

Epoxy resins as a matrix material in advanced fiber-reinforced polymer (FRP) composites

2013

Abstract: This chapter discusses the epoxy resins which, thanks to their good and versatile properties, can be considered nowadays the most important class of thermosetting polymers. In particular the chapter first reviews both the epoxy resins commonly available on the market, including a new class of bio-derived epoxy resins, and the most-used curing agents. it then describes the principal characteristics of the epoxy resins and how it is possible to enhance them by adding several fillers to the epoxy system. Finally, the chapter analyzes the main engineering fields in which epoxy resins find application today and their possible future utilization.

Assembling Magnetic Blocks: A Strategy to Control the Nuclearity and Magnetic Properties of Polynuclear Complexes

1996

Synthetic strategies dealing with the polymerization of either di-μ-hydroxocopper(II) complexes or 2,2′-bipyrimidine (bpym)-containing first row transition metal ions allow the preparation of polynuclear compounds whose structures and magnetic properties are presented here. The influence of structural and chemical parameters on the magnitude of the singlet-triplet energy gap (J) in di-μ-hydroxocopper(II) complexes [LCu(OH)2CuL]2+ with L = 2,2′-bipyridine (bpy) and bpym is analyzed and discussed. Special attention is devoted to nature of the counterion which allows the preparation of hydroxo-bridge copper(II) cubane and double cubane type complexes where all the intramolecular magnetic inter…

On the Use of the Nanoindentation Unloading Curve to Measure the Young's Modulus of Polymers on a Nanometer Scale

2005

Summary: The nanoindentation test is a fundamental tool to assess the link between morphology and mechanical properties. The preliminary results of a more exhaustive study about the applicability to polymers of the most used procedure to determine elastic modulus by indentation are reported in this short communication. A departure of the experimental conditions from the theoretical assumptions and results that give rise to the Oliver and Pharr analysis is shown to occur under a wide range of experimental conditions, with applied loads and penetration depths covering several orders of magnitude and using different indenter geometries. Unloading curves with exponents significantly larger than…

Tandem asymmetric Michael reaction-intramolecular Michael addition. An easy entry to chiral fluorinated 1,4-dihydropyridines.

2010

A novel one-pot tandem asymmetric Hantzsch-type process has been employed to generate fluorinated 1,4-dihydropyridines (1,4-DHPs) as single diastereoisomers. It involves the condensation of (R)-(+)-allyl p-tolyl sulfoxide, fluorinated nitriles, and alkyl propiolates, giving access to a new family of enantiomerically pure fluorine-containing 1,4-DHPs.