جستجوی مقالات مرتبط با کلیدواژه « octene copolymer » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

As we have stated in our previous article, ethylene-octene copolymers are much more branched than high density polyethylene, therefore, they have lower crystallinity and melting point and better processability. In addition, due to the enhancement of the desired physical and mechanical properties of the nanocomposites such as higher thermal stability and tensile properties and lower peamability in comparison with that of the pristine polymer, there is a great tendency in using this calss of materials. The improvement in physical and mechanical properties of the nanoconmposites is mainly origined from the large aspect ratios of the organoclay platelets and the interaction between the nano-sized filler and polymers which can also make the transfer of load from the matix to the filler more efficient. Moreover, the variation of viscosity with shear rate and angular frequency can provide invaluable information on the viscoelastic property of polymer melts as well as the processability of nanocomposites. In continuation to our previous paper, our aim in this article is to give some complementary information about the mechanical properties and rheological behaviors of the above-mentioned nanocomposites by reviewing the recently published papers on this area.

Polyethylenes are among of the commodity polymers with wide-spread applications. They are being used in transportation، wire and cable، food packaging، and building industries، for instance. Ethylene-octene copolymers contain more branches in respect to that of the high density polyethylene، therefore، their crystallinities and melting points are lower and can also be processed much easier. Nowadays، there are huge interests in using polymer-clay nanocomposites because of their higher desired physical and mechanical properties such as thermal stability، tensile strength and barrier resistance in comparison with that of the unfilled polymers or the polymers which are reinforced with the same amount of micro-sized fillers. Nanoclays are modified using organic modifiers such as alkylammonium ions in order to enhance their compatibility with polymers. They can also act as a nucleating agent and change the crystallinity of polymeric materials. This nano-sized filler could also affect the thermal stability and flame retardancy but the amount of influence depends on the morphology developed. In this article، our aim is to present some information about the above-mentioned nanocomposites by reviewing the recently published papers in this area.

Rheological، morphological and mechanical studies were performed on various blends of polypropylene (PP) and ethylene-octene copolymer (EOC). The oscillatory flow properties were determined at 220°C on a cone-plate rheometer (dynamic rheometer، SR 200) at an angular frequency range of 0. 01 to 100 rad/s. The rheological studies showed material flow behavior in the molten state. Scanning electron microscopy (SEM) revealed that as the amount of ethylene-octene copolymer increased، the size of elastomeric domains increased; and that dual-phase continuity occurred between 50 and 60 (wt%) of EOC. Studies on mechanical analysis showed that PP/EOC blends displayed higher impact strength than PP. With the addition ethylene-octene copolymer into polypropylene، the mechanical properties of the final blend improved because of lower elastic modulus intended for soft and flexible product and a low glass transition temperature to impart impact strength at low temperatures. This copolymer was compatible with PP in creating brightness and surface luster. The amount of long chain branches had significant effect on mechanical and rheological properties of ethylene-octene copolymer.