Search results for "plastic"

Preparation and determination of the structure of high-performance polymer blends by small-angle neutron scattering

1995

Amorphous blends from a deuterated polyaryletherketone and a polyetherimide have been prepared and investigated by neutron scattering. The used components differ remarkably in their structure antheir solution properties. The blends on the other hand are combinatorial mixtures : the scattering quantity Φ 1 Φ 2 /S(q) is independent of the composition of the blends if the polymer chains have the same length

Small angle X-ray scattering from amorphous polymers arising from heterogeneities

1973

The small angle X-ray scattering of glassy polymers (PET, PC, PVC, PMMA) and of polymer melts (PE) was studied. The dependence of the intensity scattered at small angles on the sample treatment suggests that neither the inherent structure of the pure polymer phase nor microholes are the origin of the scattering. In agreement with all experimental facts the scattering can be attributed to foreign particles such as for instance stabilizers in the polymer matrix. The consequence of this result is discussed with respect to the nodular structure of the amorphous phase and with respect to structural models of the amorphous phase. The nodular structure is not related to regions of different densit…

Designing Medical Devices Based on Silicon Polymeric Material with Controlled Release of Local Anesthetics

2012

The drug delivery systems that are the object of this article take the form of a polymer matrix made of silicone containing a drug. These devices can be used as patches for local dermal applications releasing the drug in a controlled manner. The model active agent, lidocaine hydrochloride was chosen from the range of local anesthetics. When the drug is restricted to the surface, it is released more rapidly than when it is allowed to spread evenly throughout the silicon structure. When hydrophilic polymers such as PVA and HEC are mixed in with the lidocaine hydrochloride and deposited on the surface of the polymer matrix, we observed that the burst effect was eliminated without modifying the…

Processing and adjusting the hydrophilicity of poly(oxymethylene) (co)polymers: nanoparticle preparation and film formation

2016

Handling the insoluble POM: the preparation of nanoparticles based on hyperbranched-linear-hyperbranched ABA triblock copolymers with variable hydrophilicity and composed of short hyperbranched polyglycerol (hbPG) as the A-blocks and linear poly(oxymethylene) (POM) as a B-block is described. The POM-hbPG-nanoparticles with diameters in the range of 190 to 250 nm were generated in a convenient process, combining the solvent evaporation process with the miniemulsion technique, a water borne handling for POM-copolymers. Furthermore, the film formation properties of the nanoparticles were investigated by deposition on silicon and subsequent sintering, which leads to films with a thickness in th…

1995

Redoxactive liquid crystalline (LC) side group polymers were prepared by copolymerization of liquid crystalline acrylates and ferrocene-containing acrylates. The corresponding liquid crystalline ionomers were synthesized by a reversible redox reaction. The incorporation of tetra-alkylated ferrocene derivatives leads to LC polymers with reduced redox potential. These polymers can be oxidized under mild conditions to the corresponding ionomers, which are much more stable in solution than LC ionomers containing monoalkylated ferrocenium ions. Dynamic mechanical measurements and small angle X-ray scattering (SAXS) perfomed on LC ionomers prove the existence of ionic superstructures (clusters) w…

Morphology, rheology, and mechanical properties of a new nanobiocomposite

2015

Nanobiocomposites are a new class of biodegradable polymer materials with an ultrafine phase dispersion of the order of a few nanometers in a biodegradable polymer matrix that shows very interesting properties often very different from those of conventional filled polymers. In this work the morphology and the rheological and mechanical properties of a new nanobiocomposite made of a biodegradable copolyester based blend with an organomodified montmorillonite have been investigated to evaluate its possible use in several applications. SAXS diffractograms and TEM micrographs show that the in both the adopted processing conditions an hybrid intercalated/exfoliated morphology is observed. Rheolo…

Dynamics of phase separation and critical phenomena in polymer mixtures

1987

The phenomenological mean-field theory for statics and dynamics of polymer mixtures is described, generalizing the approaches of Flory-Huggins, Cahn-Hilliard and de Gennes. Predictions are made for critical behavior, spinodal decomposition and homogeneous nucleation. The validity of the mean-field approximations is discussed with Ginzburg criteria. The results of the theory are compared to computer simulations and recent experiments.

Simulating Copolymeric Nanoparticle Assembly in the Co-solvent Method: How Mixing Rates Control Final Particle Sizes and Morphologies

2018

Abstract The self-assembly of copolymeric vesicles and micelles in micromixers is studied by External Potential Dynamics (EPD) simulations – a dynamic density functional approach that explicitly accounts for the polymer architecture both at the level of thermodynamics and dynamics. Specifically, we focus on the co-solvent method, where nanoparticle precipitation is triggered by mixing a poor co-solvent into a homogeneous copolymer solution in a micromixer. Experimentally, it has been reported that the flow rate in the micromixers influences the size of the resulting particles as well as their morphology: At small flow rates, vesicles dominate; with increasing flow rate, more and more micell…

Photo-re-stabilisation of recycled post-consumer films from greenhouses

2004

The photo-oxidation behaviour of recycled post-consumer films from greenhouses has been studied in order to evaluate the environmental resistance of these secondary materials and the effect of some stabilising agents. The presence of the UV absorber slows down the weathering of the post-consumer materials. After about 1000 h of accelerated weathering the unstabilised post-consumer material becomes brittle, while the re-stabilised post-consumer film becomes fragile only after about 1500 h. A synergistic effect is observed when an antioxidant and an UV stabiliser are added. Indeed, in this case, the recycled material is not brittle even after more than 1700 h. These last results can be probab…

Durability of a strach-based biodegradable polymer

2007

Abstract The photo-oxidation and the photo-stabilization of a commercial biodegradable polymer have been investigated in order to establish the possibility of using this polymer as raw material for films for agriculture. The degradation has been followed by measuring the mechanical properties as a function of photo-oxidation time and in particular by following the elongation at break. The virgin polymer, made from maize starch and a synthetic biodegradable polyester, shows poor resistance to the UV irradiation as observed by the fast decay of the elongation at break, but the presence of small amounts of conventional UV stabilizers strongly improves the durability of this polymer. The UV sta…