Search results for "linear low-density polyethylene"
showing 10 items of 32 documents
Activity and Thermal Stability of Cobalt(II)-Based Olefin Polymerization Catalysts Adorned with Sterically Hindered Dibenzocycloheptyl Groups.
2019
Five examples of unsymmetrical 2-(2,4-bis(dibenzocycloheptyl)-6-methylphenyl- imino)ethyl)-6-(1-(arylyimino)ethyl)pyridine derivatives (aryl = 2,6-Me2C6H3 in L1
SHEAR BEHAVIOUR OF MOLTEN LINEAR LOW DENSITY POLYETHYLENE.
1984
The rheological behaviour of molten polyethylene has been widely studied especially with respect to the different structure of the high density and low density samplesI–I0. In particular it is well known that the presence in the LDPE of long chain branching alters dramatically the whole flow curve, the activation energy, the die-swell, the instability phenomena, etc.
1990
The countercurrent extraction method recently developed for the continuous polymer fractionation (CPF) was applied to linear polyethylene (Mw = 55 kg/mol; Mn = 16,7 kg/mol). At temperatures higher than 130°C, moderately concentrated solution of polyethylene were extracted to remove the low-molecular-weight components. Discontinuous fractionation experiments served to detect the best suited solvents. Diphenyl ether was chosen to demonstrate that the present extraction can be performed even with the same single solvent used to prepare the feed. For very high-molecular-weight polymers, mixed solvents are, however, normally better than single ones, since they allow an easier tailoring of thermo…
Influence of a sterically hindered amine on the photo-oxidation of low density/linear low density polyethylene blends
1990
Abstract Low density/linear low density polyethylene blends show a rate of degradation of the mechanical properties during photo-oxidation which increases with the content of the linear polymer. The use of a sterically hindered amine as UV stabilizer greatly improves the resistance of these blends to UV irradiation. The effectiveness of the stabilizer increases with the content of linear low density polyethylene.
Improvement of photo-stability of LLDPE-based nanocomposites
2006
LLDPE-based nanocomposites undergo faster photo-oxidation than the unfilled matrix and the extent of their physical properties deterioration, namely elongation at break and tensile strength, is dependent on the organo-nanoclay loading. The observed acceleration is not due to faster photo-oxidation but rather due to a reduction of the oxidation induction time. The presence in the organoclays of trace amounts of metal ions may be promoting catalytic photodegradation. While UV absorbers provide useful protection, use of a metal deactivator has been found to greatly enhance the photo-stability of the LLDPE-based nanocomposites. Combinations of a metal deactivator and UV absorber yield synergist…
Polietylen liniowy małej gęstości
2002
Artykuł o charakterze przeglądowym dotyczy jednego z gatunków polietylenu, tj. liniowego polietylenu małej gęstości (PE-LLD) stanowiącego kopolimer etylenu z niewielką ilością (kilku %) wyższej l-olefiny otrzymywany metodą polimeryzacji koordynacyjnej z udziałem metaloorganicznych układów katalitycznych. Omówiono wpływ typu katalizatora, w szczególności nowoczesnych układów metalocenowych, na aktywność w kopolimeryzacji i efektywność wbudowania komonomeru do łańcucha polietylenowego. Przedstawiono przemysłowe metody otrzymywania PE-LLD oraz charakterystykę tego produktu na tle znanych gatunków polietylenu - PE-LD i PE-HD. Omówiono także wpływ budowy chemicznej PE-LLD na jego podstawowe właś…
1986
Ultimate tensile properties and dart impact behaviour of coextruded films of LDPE and LLDPE were compared with those of films made from blends of the same resins. The effect of composition and of both blow up ratio and axial draw ratio of the blowing process on film properties was explored. The results indicate that, at least for semicompatible systems like that considered here, films made from blends and coextruded ones have mechanical properties very close to each other. Die Festigkeitseigenschaf ten und das Verhalten beim Kugelfalltest von coextrudiertcn Filmen aus LDPE und LLDPE wurden mit den entsprechenden Eigenschaften von aus Mischungen dieser Polymere hergestellten Filmen vergliche…
The antioxidant effect in controlling thermal degradation of a low density polyethylene blown film
2004
Abstract It is well known that antioxidants are widely used to prevent thermal degradation of high density and linear low density polyethylene. Antioxidants are not always present in low density polyethylene and only small amounts are usually added to these resins. In this work the effect of an antioxidant system on a low density resin having MFI (190 °C/2.16 kg)=2 g/10′ and density 0.9230 g/cm3 has been studied. Its effect on melt viscosity has been studied by means of a batch mixer and the torque vs time behaviour has been analysed. The results show that a maximum in the torque vs time curve can be seen for the material containing antioxidant. In contrast, the material without antioxidant…
Ion bombardment of polyethylene—influence of polymer structure
2007
Abstract Polyethylenes of various macromolecular and supermolecular structures were studied from the point of view of their susceptibility to an ion beam treatment. An influence of molecular weight (Mw), molecular weight distribution (Mw/Mn) and the degree of branching were compared within the set of low-density polyethylenes (LDPE) studied. An influence of the length of branches was compared between LDPE, linear low-density (LLDPE) and high-density (HDPE) polyethylenes. An influence of the degree of crystallinity and the morphology of a crystalline phase were compared for HDPE samples solidified under various thermal conditions and ultra-high molecular weight polyethylene (UHMWPE). Plate p…
Carboxylation of a linear low density polyethylene via gamma irradiation in presence of carbon dioxide in subcritical and supercritical conditions
1994
Abstract In this work the molecular modifications induced in a linear low density polyethylene gamma irradiated in presence of carbon dioxide both in subcritical and supercritical conditions are presented. The obtained results indicate that this process can be a new and interesting way in order to graft oxidized groups in the polyethylene chains. Moreover it is worth noting that, together with these functionalization reactions, also a significant crosslinking occurs, with improvement in some mechanical tensile behaviour.