Search results for "Surfaces"

Synthesis of PP-LCP graft copolymers and their compatibilizing activity for PP/LCP blends

1998

The aim of this work was the synthesis of new graft copolymers consisting of polypropylene (PP) backbones and liquid crystalline polymer (LCP) branches, to be used as compatibilizing agents for PP/LCP blends. The PP-g-LCP copolymers have been prepared by polycondensation of the monomers of a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2), that is, sebacic acid (S), 4,4′-dihydroxybiphenyl (B), and 4-hydroxybenzoic acid (H) in the mole ratio of 1 : 1 : 2, carried out in the presence of appropriate amounts of a commercial acrylic-acid-functionalized polypropylene (PPAA). The polycondensation products, referred to as COPP50 and COPP70, having a calculated PPAA concentration of 50 and…

Structure and Mechanical Properties of Melt Intercalated Po1lypropylene–Organomontmorillonite Nanocomposites

2010

The preparation and properties of polymer nanocomposites, obtained by melt-compounding of polypropylene (PP) and organomontmorillonite (OMMT) modified by different alkyl ammonium salts, are described. A copolymer of maleic anhydride and PP was used as a compatibilizing additive. Nanocomposites with OMMT content of 1, 5 and 10 wt% were prepared and tested. The influence of OMMT content on the tensile stress–strain curves, elastic modulus, yield and tensile strength, and ultimate elongation of the nanocomposites is determined. The results of measuring the microhardness and impact strength of polymer nanocomposites are presented. Long-term creep tests were performed to predict the long-term de…

Volatile compounds extracted from polypropylene sheets by hot water :influence of the temperature of sheets injection

1993

A study was made on polypropylene (PP) pellets degraded and not degraded and pointed out the presence and olfactive importance of volatile components extracted from PP pellets by hot water. Plastic packaging materials correspond to a further step of manufacturing: the injection step, and this is often conducted at high temperature. PP (not degraded) and PP-CR (degraded) were transformed into sheets at several temperatures; Lickens-Nickerson extracts were made and allowed the quantification of volatile compounds already identified. A statistical analysis showed that temperature was a very significant parameter. An increasing injection temperature (275 or 300°C° creates increasing quantities …

Relationship between the residual and total strain from creep‐recovery tests of polypropylene/multiwall carbon nanotube composites

2020

Recycling of inside upholstery of end-of-life cars

2005

A model study for the recycling of the interior upholstery plastic parts of end-of-life cars has been carried out by reprocessing the homogenized scraps of an upholstery farm in the presence of different compatibilizer precursors, such as an ethylene-glycidylmethacrylate copolymer (EGMA), a maleic anhydride functionalized thermoplastic elastomer (SEBS-MA), etc. The investigated scraps contained recycled polyethylene (from agricultural uses) and poly(ethylene terephthalate), as the main components, plus minor proportions of polypropylene, polyamide-6, and other additives, including an ethylene copolymer (EC), probably an ethylene-acrylic acid copolymer, which is used to compatibilize the car…

On the mechanism of compatibilization of polyolefin/liquid crystalline polymer blends with graft copolymers

2000

The compatibilization mechanism of some compatibilizers for blends of polyolefins with a liquid crystalline polymer (LCP) was studied. Polyethylene (PE) and polypropylene (PP) were blended with a semirigid LCP (SBH) in a batch mixer, either with and without compatibilizers. The latter were two commercially available samples of functionalized polyolefins, that is, a PE-g-MA (HDM) and a PP-g-AA (Polybond 1001) copolymer and some purposely synthesized PE-g-LCP and PP-g-LCP copolymers. Microtomed films of the binary and the ternary blends were annealed at 240°C on the hot stage of a polarizing microscope and the changes undergone by their morphology were recorded as a function of time. The resu…

Some Features of Polymeric Membranes for Water Purification via Membrane Distillation

2011

Polymeric membranes are currently adopted in water purification processes, such as reverse osmosis (RO) and membrane distillation (MD). This latter technique is very promising for separation effectiveness and energy savings. A valuable and effective MD unit must be equipped with polymeric membranes that exhibit specific properties, for example, hydrophobicity, a narrow pore size range, a high water penetration pressure, and a large vapor permeability. In this work, we present and examine the main features of membranes for MD processes, with the aim of experimentally evaluating the related performances. Scanning electron microscopy analysis was carried out for a first estimate of the pore si…

SAXS investigation on aggregation phenomena in supercritical CO2.

2004

Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate- b-Perfluoro octyl acrylate (PVAc- b-PFOA) block copolymer in supercritical CO(2) are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO(2) density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO(2)…

A simple approach towards one-dimensional mesoporous carbon with superior electrochemical capacitive activity.

2009

One-dimensional (1D) mesoporous carbons with highly ordered 3D interconnected pore structure and large-diameter pore size (10–20 nm) have been synthesized by a simple precursor-controlled thermolysis approach; such unique carbonaceous frameworks show superior capacitive behavior in electrochemical double-layer capacitors.

Water Dynamics at the Solid-Liquid Interface to Unveil the Textural Features of Synthetic Nanosponges.

2020

A Fast-Field-Cycling NMR investigation was carried out on a set of polyurethane cyclodextrin nanosponges, in order to gain information on their textural properties, which have been proven to be quite difficult to assess by means of ordinary porosimetric techniques. Experiments were performed on both dry and wet samples, in order to evaluate the behavior of the “non-exchangeable” C-bound 1H nuclei, as well as the one of the mobile protons belonging to the skeletal hydroxyl groups and the water molecules. The results acquired for the wet samples accounted for the molecular mobility of water molecules within the channels of the nanosponge network, leading back to the possible pore size distrib…