Search results for "plastic"

Tracer diffusion in polymer and organic liquids close to the glass transition studied by forced rayleigh scattering

2007

Translational diffusion coefficients D of photochronic dye molecules have been measured by forced Rayleigh scattering in polymer diluent systems at compositions from pure polymer to pure diluent. D could be measured down to below the glass transition temperature T g. In the pure diluent, D(T g) was found typically about two decades below that in the pure polymer but still far above the Stokes-Einstein prediction extrapolated from high temperatures. Some experimental results are in contrast with predictions from free-volume theory.

Structural and Gelation Characteristics of Metallo-Supramolecular Polymer Model-Network Hydrogels Probed by Static and Dynamic Light Scattering

2021

Supramolecular polymer gels are a promising class of materials whose polymer components are connected by transient bonds such as metal–ligand interactions, thereby spanning a dynamic network throug...

Synthesis of oxide-supported vanadium catalysts and their activity in ethylene polymerization

1999

Reactive dual-component compatibilizers for polycarbonate/high-density polyethylene blends

1995

Enhanced compatibility for blends of polycarbonate with high-density polyethylene has been achieved with the addition of 5 wt% compatibilizers composed of 1 : 1 mixtures of phenoxy and the sodium ionomer of an ethylene methacrylic acid copolymer at two different levels of neutralization. Both components of the compatibilizer have been found to be capable of reacting with the polycarbonate phase to produce branched polymer chains. These impart a degree of compatibilization in polycarbonate/high-density polyethylene blends, however at higher levels of sodium in the compatibilizer the polycarbonate phase undergoes crosslinking reactions, causing severe embrittlement. Compatibilization effects …

Reactive nanorods based on activated esterpolymers: a versatile template-assisted approach for the fabrication of functional nanorods

2011

A new route for the fabrication of polymeric nanorods with functional moieties via post-modification of reactive nanorods is described. To this end reactive nanorods with a homogenous and narrow size distribution were fabricated by utilizing an anodic aluminium oxide (AAO) template-assisted approach. The nanorods are based on activated pentafluorophenyl esters, to enable quantitative post-modification with amines under very mild reaction conditions yielding the corresponding functionalized amide. Post-modification with fluorescent dyes as well as the conversion into well-dispersed rod-shaped poly(N-isopropylacrylamide) (PNIPAM) hydrogels that exhibit a thermal-responsive phase transition wa…

Fabrication of Robust High-Quality ORMOCER® Inverse Opals

2006

The nanostructuring of ORMOCER® to form inverse opals is described. For this purpose a polymer opal is used as a template and infiltrated with liquid ORMOCER®. After photopolymerization of the resin the host opal is dissolved in tetrahydrofuran and an ORMOCER® inverse opal is obtained. It shows excellent periodicity (by SEM) and optical properties to reveal a high degree of face centered cubic order. This replication process leads to a nanostructured photonic crystal with the outstanding mechanical properties of ORMOCER® and high temperature stability up to 350 °C.

Processability and Properties of Re-Graded, Photo-Oxidized Post-Consumer Greenhouse Films

2005

The recycling of post‐consumer plastics leads, in general, to secondary materials having properties worse than those of the reclaimed material and certainly worse than those of the same virgin polymer. This is because of the degradation undergone by the objects during their use and because of the thermo‐mechanical degradation undergone during the reprocessing operations. The change of the molecular architecture is responsible for this worsening of properties. The use of stabilizing systems can slow the degradation during the melt processing but cannot give any improvement of the final properties of the material. In order to enhance the properties of the recycled plastics, some rebuilding of…

Re-gradation of Photo-oxidized Post-consumer Greenhouse Films

2005

The degradation undergone by the polymers during their use and because of the thermo-mechanical degradation undergone during the reprocessing operations provokes, among other effects, the decrease of the molecular weight. The change of the molecular architecture is responsable for the deterioration of all the properties. In order to restore the properties of post-consumer recycled plastics, some rebuilding of the molecular structure is necessary. In this work, photo-oxidized films for greenhouses were reprocessed in presence of additives able to react with the polyethylene in order to form branching and cross-linking, improving the properties of these post-consumer plastic.

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…

Cylindrical Polymer Brushes with Elastin-Like Polypeptide Side Chains

2013

Monodisperse high molar mass elastin-like polypeptide macromonomers comprising 20 pentasequences (M = 8332 g/mol) were radically polymerized to high degrees of polymerization Pw = 590. Polymerization was conducted in water well above the lower phase transition temperature, i.e., in the phase separated regime. The resulting polymers adopt a cylindrical shape as demonstrated by AFM pictures of solutions spin-cast on mica. The directional persistence of the cylindrical brushes was determined by static light scattering to Kuhn statistical segments lengths lk = 120 nm at 5 mM aqueous NaCl solution which decreased to lk = 54 nm at 0.65 M NaCl. Upon polymerization the phase transition temperature …