Search results for "blend"
showing 10 items of 421 documents
Recycling of compatibilized and uncompatibilized nylon/polypropylene blends
2001
The recycling of compatibilized and uncompatibilized nylon6/polypropylene blends has been carried out by repetitive extrusions. The change of the properties of the blends is a function not only of the number of reprocessing steps but also of the type of compatibilizer. The worsening of the mechanical properties is small and, indeed, some improvement can be observed after one or two extrusion steps for some blends. It is hypothesised that the decrease of the molecular weight, the typical effect occurring during this thermomechanical treatment, is counterbalanced and overcome by the possible formation of new copolymers that act as bridges between the two phases. This behaviour is displayed by…
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 of isotactic polypropylene/ hydrogenated oligo(cyclopentadiene) blends: 1. Polypropylene-rich blends
1998
Blends of isotactic polypropylene (iPP) and hydrogenated oligo(cyclopentadiene) (HOCP) containing 30% or less HOCP have been studied by small-angle X-ray scattering in the temperature range 25 to 160°C. The structure of blends has been analysed in terms of a pseudo two-phase model consisting of stacks of lamellae whose thickness is a function of temperature and composition. Structural parameters of the model have been derived and their temperature and composition dependences have been interpreted in the light of existing theories.
Thermal and Mechanical Properties of Unvulcanized Polypropylene Blends with Different Elastomers: Ethylene-Propylene-Diene Terpolymer, Nitrile-Butadi…
2013
In this work, composites of isotactic polypropylene (PP) with three unvulcanized elastomers – terpolymer of ethylene-propylene-dicyclopentadiene (EPDM), chlorinated polyethylene (CPE) and copolymer of acrylonitrile-butadiene (NBR) – have been investigated. The purpose of the investigation was to create PP/elastomer blend composites of significantly different compositions (with an excess of PP, intermediate ones, and with an excess of elastomer) and to study the dependence of tensile behaviour and elastic properties on the blends with different component ratio. Tensile properties have been recognized from the stress-strain curves. The changes of elastic modulus have been characterized with r…
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…
Characterization of blends of polypropylene with a semirigid liquid-crystal copolyester
1991
Abstract Blends with a liquid-crystal polymers (LCP) as one component show, in general, very interesting properties. Reduction of shear viscosity and improvement of mechanical properties are very remarkable. High melting temperatures and high costs of the LCP limit the use of these blends. A new class of thermotropic LCPs with flexible spaces, with relatively low melting temperatures, can overcome the first problem. In this work, rheological and mechanical properties of blends of polypropylene with low contents of this LCP are presented. Torque during extrusion and viscosity decrease with LCP content. Elastic modulus is remarkably increased when the LCP phase is oriented.
Reduction of the interfacial tension between ‘immiscible’ polymers: to which phase one should add a compatibilizer
2001
Abstract The reduction of interfacial tension σ between polyethylene oxide (PEO) and polypropylene oxide (PPO) by either a triblock copolymer EO–PO–EO or a diblock copolymer styrene–EO was studied by means of the pendant drop method from 70 to 120°C. Time independent data correspond to stationary states and do not represent equilibrium information. The addition of the compatibilizer to the PPO phase is approximately twice as efficient as the addition to the PEO phase for both block copolymers. Knowing the concentration dependence of σ for one of the coexisting phases it is possible to forecast the effects resulting from the addition of the other phase by means of model considerations based …
Time–temperature correspondence prediction of stress relaxation of polymeric materials from a minimum of data
2002
Abstract We have determined the stress relaxation of a longitudinal polymer liquid crystal (PLC), polypropylene and their blends containing 10 and 20% of the PLC at the constant strain of 0.5%. The results for nine temperature levels in the range between 20 and 100 °C were used to create master curves for T ref =20 ° C . The temperature shift factors aT were calculated using a general formula derived by one of us and based on free volume vf and the chain relaxation capability model. The predicted values agree with the experimental ones for all materials studied within limits of the experimental accuracy. Moreover, the relation between the shift factor aT and the reduced volume ṽ has been us…
Structure of isotactic polypropylene–hydrogenated oligo(cyclopentadiene) (iPP–HOCP) blends Part II. HOCP-rich blends
2000
Abstract Blends of isotactic polypropylene (iPP) and hydrogenated oligo(cyclopentadiene) (HOCP) were investigated to gain structural information by means of both SAXS and SANS techniques. The composition range (from 30 to 60% w/w HOCP content) and the temperature range (between 25 and 160°C) were chosen in order to cover the miscibility gap in the phase diagram of the material system. In a previous report, blends lying outside the miscibility gap have been investigated and the corresponding SAXS patterns were interpreted in terms of a pseudo-two phase model. For the SAXS patterns, blends lying inside the miscibility gap are rather hard to be interpreted in terms of such a model. On the othe…
Effect of the Orientation on the Properties of Compatibilized Polypropylene/Liquid Crystal Polymer Blends
1999
Abstract Blends of polypropylene and a semirigid liquid crystal polymer have been compatibilized with an acrylic acid modified polypropylene and with an ad-hoc synthesized graft copolymer made from polypropylene and from the monomers of the liquid crystal polymer. The two compatibilizers improve the adhesion and the mechanical properties of the two incompatible phases. The two compatibilizers give about the same results. The effect of the compatibilization improve also the orientation of the liquid crystalline polymer particles and the mechanical properties.