Search results for "High-density"
showing 10 items of 139 documents
Rheological and mechanical properties of biodegradable nanocomposites
2018
Polymer nanocomposites have gained huge interest over the last decade. However, traditional thermoplastic nanocomposites do not match the rising concern about environmental issues. Therefore, during the last years, the search for biodegradable polymer nanocomposites is gaining importance. Most of biobased (i.e. based on biodegradable/bioderived polymer matrices) nanocomposites have poly(lactic acid), PLA, as matrix. However, it is of clear interest to take into account also different biobased polymer matrices, such as MaterBi. In this work, we prepared bionanocomposites containing MaterBi or a PLA-based polymer matrix, with two different kinds of nanofillers (organomodified clay and nanosiz…
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 …
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…
Effect of the Components Molar Mass and of the Mixing Conditions on the Compatibilization of PE/LCP Blends by PE-g-LCP Copolymers
1999
The rheology, morphology, and mechanical properties of blends of high-density polyethylene (HDPE) with a semiflexible liquid crystalline copolyester (SBH) were studied in order to assess the compatibilizing ability of added PE-g-SBH copolymers, and its dependence on the molar mass of the PE matrix, and on the technique used for blend preparation. The PE-g-SBH copolymers were synthesized as described in previous articles, either by the polycondensation of the SBH monomers in the presence of a functionalized PE sample containing free carboxyl groups, or by reactive blending of the latter polymer with preformed SBH. Two samples of HDPE having different molar masses, and two samples of SBH with…
Recycling of high density polyethylene containers
1997
The recycling of homogeneous high density polyethylene from containers for liquids gives rise to materials having mechanical properties that are strongly dependent on the reprocessing apparatus and the processing conditions. The thermomechanical degradation during processing gives rise to different modifications of the structure depending on the temperature, residence time and applied stress. In general, it is possible to say that if the reprocessing operations are carried out in apparatus with low residence time, the mechanical and rheological properties of the raw materials are only slightly influenced by the recycling operations. Significant degradation phenomena and reduction of some me…
Prediction of the flow curves of thermoplastic polymer/clay systems from torque data
2014
Abstract The aim of this work was to determine some relevant rheological parameters of polymer/clay systems using mixing torque and mixing speed data obtained during processing in an internal mixer. The method used was originally proposed by Marquez et al. for monophase polymers, and is here applied to polymer/clay systems for the first time. Several clay-containing composites based on different polymer matrices (i.e., LDPE, HDPE, PA6, EVA) were used to verify the effectiveness of the method for measuring the flow curves of these polymer/clay systems. The results indicated that, for all the systems at low clay level, the rheological curves calculated with the Marquez method fit quite well t…
On the Improvement of the Processability of UHMW-HDPE by Adding a Liquid Crystalline Polymer and a Fluoroelastomer
2001
Ultra-high molecular weight polyethylene possesses many interesting properties but a very bad processability. This material is not usually processed in conventional devices but only by compression moulding and RAM extrusion. Low molecular weight polyethylene can be used to improve the processability. In this work small amounts of a fluoroelastomer and of a liquid crystalline polymer have been used as processing aids to improve the extrudability of this polymer. In fact, the die pressure decreases whereas the output flow rate slightly increases with increasing concentration of the processing aids. Solution viscosity data shows that reduction of the mechanical stress during extrusion decrease…
Melt Strength and Extensibility of High-Density Polyethylene
1984
The extensional flow of polymer melts has been extensively studied because of its importance in many technological processing operations and, from a more fundamental point of view, because the tensile properties of the polymer melts cannot be correlated directly with shear viscosity behavior.1–5
Morphology and Rheology of HDPE/LCP Blends Compatibilized by a Novel PE-g-LCP Copolymer
1999
A novel graft copolymer (PE-g-LCP) consisting of polyethylene (PE) backbones and liquid crystalline polymer (LCP) branches was synthesized via reactive blending of an acrylic acid-functionalized PE (Escor 5000 by Exxon) with a semiflexible LCP (SBH 1 : 1 : 2 by Eniricerche S.p.A.). The crude reactive blending product (COP) was shown by investigation of the fractions soluble in boiling toluene and xylene and of the residue to contain unreacted Escor and SBH, together with the graft copolymer forming the interphase. The compatibilizing activity of COP for PE/SBH blends, compared to that of pure Escor, was investigated using two PE grades. The COP addition into 80/20 PE/SBH blends caused a muc…
The role of organoclay in promoting co-continuous morphology in high-density poly(ethylene)/poly(amide) 6 blends
2008
The effect of organically modified clay on the morphology, rheology and mechanical properties of high-density polyethylene (HDPE) and polyamide 6 (PA6) blends (HDPE/PA6 ¼ 75/25 parts) is studied. Virgin and filled blends were prepared by melt compounding the constituents using a twin-screw extruder. The influence of the organoclay on the morphology of the hybrid was deeply investigated by means of wide-angle X-ray diffractometry, transmission and scanning electron microscopies and quantitative extraction experiments. It has been found that the organoclay exclusively places inside the more hydrophilic polyamide phase during the melt compounding. The extrusion process promotes the formation o…