Octene Copolymer Research Articles

Multiple‐Injection Method in High‐Temperature Two‐Dimensional Liquid Chromatography (2D HT‐LC)

Comprehensively characterizing the relationship between the distributions with regard to chemical composition (CCD) and molar mass (MMD) of polyolefins is vital to establish structure–property relationships. Two‐dimensional high‐temperature liquid chromatography (2D HT‐LC), which couples a high‐temperature solvent gradient interactive chromatography (HT‐SGIC) step for compositional separation with a high‐temperature size exclusion chromatography (HT‐SEC) step for MMD determination in an on‐line manner is emerging as a tool of choice to satisfy this necessity. A serious problem commonly associated with multidimensional chromatography is the very low detector response (DR) due to the dilution in the HT‐SEC step. Using higher sample concentrations or larger sample loops cannot address this appropriately because injections may become irreproducible, or poorly shaped peaks may result due to concentration effects. This paper shows that stacked injections (repeatedly injecting a polymer sample and then starting the desorption step) is a unique way to overcome these difficulties. 2D HT‐LC analysis of blends of ethylene/1‐octene copolymers using stacked injections proves that the DR can be significantly enhanced without co‐elution of the blend components or overloading of the column. image

Toughening of Poly (Butylene Terephthalate) with Epoxy-Filled Poly (Ethylene–Octene) Copolymer

Toughened poly (butylene terephthalate) (PBT) with triglycidyl isocyanurate (TGIC)-filled poly (ethylene–octene) (POE) was prepared by melt reaction extrusion. For retarding the reaction extent between PBT and the epoxy component, the TGIC was first blended with POE to enwrap its reactive epoxy groups. Then, the TGIC-filled POE was used to melt blend with PBT. The Fourier transform infrared (FTIR) spectra showed that no other peaks appeared in the POE/TGIC specimens except for those originally existing in pure POE and TGIC. The rheological results further confirmed that no reaction occurred between the epoxy and the POE matrix. When the POE/TGIC was blended with PBT, a distinct increase of the viscosity suggested that the migration of the TGIC from POE to PBT during the melt processing induced chain extension reactions of PBT. The results obtained from DSC and DMA revealed that the chain extension of PBT induced by the reaction with TGIC restricted the mobility of PBT chains leading to a limitation of the recrystallization-remelting process and an increase of the glass transition temperature of PBT. The mechanical tests showed that the presence of TGIC in the POE phase distinctly improved the toughness of PBT. Compared to the case of a PBT/POE (80/20, wt%/wt%) blend, the elongation at break and impact strength of the system filled with 5 phr TGIC were increased more than three and six times, respectively.

Thermal stability of polyacetal/ethylene-octene copolymer/zinc oxide nanocomposites

In this work we investigate binary blends of polyoxymethylene and ethylene octene copolymer (EOC) and their composites with nanostructured zinc oxide (ZnO). EOC content in the composites varies from 0 to 50 wt. %. The amount of ZnO filler in the composites is changed in the interval from 0 to 5 wt. %. Thermal properties of composites are investigated with thermogravimetric analysis and differential scanning calorimetry. It is observed that ZnO addition increases thermal stability of the investigated composites.

Mesophase Formation in Random Propylene-co-1-octene Copolymers

The development of the mesophase has been studied by either fast scanning calorimetry or conventional DSC in a series of random propylene-co-1-octene copolymers. The results show that the mesophase formation rate can be easily tailored in a very wide range of magnitudes, covering almost 4 orders. That decrease is similar to that found previously in propylene-co-1-pentene copolymers at the same wt % of counits. On the contrary, the pertinent unit for the melting point depression (and for the crystallization temperatures) is found to be the mol % comonomer content. Consequently, the “kinetic” parameters in the ordering of iPP copolymers can be tailored somewhat independently of the transition temperatures just by changing the size of the comonomeric units. Additional X-ray diffraction experiments, employing either conventional or synchrotron radiation, were also carried out on these 1-octene copolymers in order to determine the precise nature of the different transitions.

Plasticity/damage coupling in fibrillar silicate-reinforced polypropylene/ethylene–octene copolymer composite under strain-controlled loading

Mechanical properties and deformation mechanism of polypropylene (PP) filled with different weight percentage of ethylene–octene copolymer (EOC) and fibrillar silicate attapulgite (ATP) clay were investigated under uniaxial cyclic loading at constant crosshead speed to evaluate plasticity/damage coupling behavior. With increasing EOC and clay content, PP exhibited typical plastics response with marked stress drop at yield followed by steady state plastics region up to rupture. The addition of 3 wt% ATP clay to the PP/EOC blend shows enhanced impact strength up to four times compared to PP with decrease in yield strength by 24% implied synergistic toughening effect. Volume strain, which characterizes deformation damage, steadily increased over the whole plastics stage up to 5.2 for axial strain of 0.30 after a critical tensile strain of 0.05. The small energy value observed for large volume strain revealed matrix shear deformation as the controlling factor for energy dissipation without crazing. Fractography observation using scanning electron microscopy revealed formation of debonding and cavitations on the surface of PP matrix, contributing increase in the volume of all compositions.

Effect of Operating Conditions on Dynamic Crystallization of Ethylene/1‐Octene Copolymers

Dynamic crystallization (DC) is a new characterization technique for measuring the chemical composition distribution (CCD) of semicrystalline copolymers. This technique fractionates polymers based on chain crystallizabilities under a constant cooling rate; a solvent is also fed through the column at a constant flow rate during the crystallization to enhance the physical separation of the polymer fractions. In this work, a DC model for ethylene/1‐olefin copolymers on the basis of population balance, crystallization kinetics, and axial dispersion is proposed. This model is found to describe the experimental DC profiles of an ethylene/1‐octene copolymer at various operation conditions very well. image

Electrically conductive and super-tough polypropylene/carbon nanotube nanocomposites prepared by melt compounding

Polyethylene–octene copolymer (POE), maleic anhydride-grafted POE (POE-g-MA) and ultrahigh molecular weight polyethylene (UHMWPE) were incorporated as second polymer components with polypropylene/carbon nanotube (PP/CNT) components by melt compounding and their influences on electrical conductivity and toughness of the nanocomposites were studied. POE-containing nanocomposites exhibit not only high electrical conductivity but also super-toughness, which are not considerably dependent on compounding sequences. Though UHMWPE does not largely affect the electrical conductivity of PP/CNT nanocomposites due to its impermeable feature, its toughening efficiency on PP/CNT nanocomposites is rather low. Irrespective of the compounding sequences, the incorporation of POE-g-MA adversely affects the formation of conducting network of CNTs due to its attraction with CNTs, leading to an insulating PP/CNT nanocomposite even with 30wt% of POE-g-MA. Among the three second polymer components, POE is much preferred in actual applications as it makes PP/CNT nanocomposites super-tough while the conducting feature of the nanocomposites is retained.

Synthesis of ethylene/1‐octene copolymers with controlled block structures by semibatch living copolymerization

A kinetic model was developed for the living copolymerization of ethylene/1‐octene using the fluorinated FI‐Ti catalyst system, bis[N‐(3‐methylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] TiCl2/dried methylaluminoxane is presented. The model was first validated by batch polymerization experiments. Kinetic parameters were estimated from the model correlations with online ethylene consumption rates and end‐of‐batch copolymer molecular weight. The model was then used to calculate the microstructural properties of ethylene/1‐octene copolymers with controlled composition profiles (uniform, diblock, and step triblock), which were synthesized using sequential comonomer feeding policies in semibatch copolymerization. The synthesized block copolymers had the exact composition distributions and molecular weights as the model simulated. It was demonstrated that the polymer chain microstructure in the living copolymerization of olefins could be precisely regulated by using semibatch comonomer feeding policies. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4686–4695, 2013

Mathematical Model of Dynamic Crystallization of Ethylene/1‐Octene Copolymers

SummaryDynamic crystallization (DC) is a fractionation technique to enhance physical separation of polymers with different chain crystallizabilities by crystallizing polymer chains from solution in a column under a constant flow rate. In this work, a mathematical model for describing fractionation mechanism of dynamic crystallization based on the concept of population balance, crystallization kinetic, and dispersion models is proposed by the first time. The model was validated with experimental DC analysis of three ethylene/1‐octene copolymers. The simulated DC profiles were found to describe experimental results well.

Blends of ethylene–octene copolymers with different chain architectures – Morphology, thermal and mechanical behavior

Blends of two elastomeric ethylene–octene copolymers with similar octene contents having a random (ORC) and a blocky architecture (OBC) are prepared by melt mixing. The thermal and mechanical properties of ORC, OBC and their blends are investigated by DSC, dynamic mechanical analysis and tensile tests. The morphology of the semi-crystalline samples is studied by AFM and WAXS. Two types of crystals have been observed: (i) Orthorhombic crystals forming lamellae with an estimated thickness of about 13 nm composed mainly of long polyethylene-like sequences of OBC that melt a temperature of about 120 °C and (ii) fringed micellar crystals with a thickness of 2–4 nm formed basically by short polyethylene-like sequences of ORC that have melting temperatures between 30 and 80 °C. The amorphous phase contains a relatively homogeneous mixture of segments of both components indicated by the relatively uniform shape of the loss modulus peaks from dymamic-mechanical measurements for all investigated copolymers and blends. ORC crystallization is hindered in blends as indicated by lower melting enthalpies. This might be related to the high octene content of the amorphous phase at the relevant crystallization temperature as well as geometrical constraints since ORC crystallization occurs in an already semi-crystalline polymer. The results of tensile tests show that the mechanical behavior can be tailored via blend composition and morphology of the semi-crystalline material. The findings clearly indicate that blending is a powerful strategy to optimize the properties of polyolefin-based copolymers.

Flammable and mechanical effects of silica on intumescent flame retardant/ethylene–octene copolymer/polypropylene composites

The flammable and the mechanical effects of silica (SiO2) on the halogen-free, flame-retarded ethylene–octene copolymer (POE)/polypropylene (PP) composites were investigated. Through the thermal stability analysis and the combustion test, it was found that the SiO2 had a synergistic effect on the intumescent flame retardant (IFR), especially when the SiO2 content was 3 wt%. According to the results of mechanical properties, the tensile strength of composites increased with the rising SiO2 content and most of the impact strength is retained. The fracture morphology showed the state of SiO2/IFR particles in the POE/PP blends, which reflected that with the increasing SiO2 content and the decreasing IFR content, the aggregates became less compact and the size of aggregates became smaller.

Synthesis and Characterization of Ethylene/1‐Octene Copolymer Based Ionomer Nanocomposite

SummaryA new type of ionomeric nanocomposite based on elastomeric ethylene/1‐octene copolymer (EOC) and organophilically modified layered silicate was synthesized through sulfonation of the EOC followed by solution casting. The morphology–mechanical properties correlation of the product was studied with the help of scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and recording microindentation measurement. The nanocomposite with uniformly distributed filler morphology could be conveniently prepared. It was found that the Martens hardness of ionomer nanocomposite comprising 5 wt.‐% layered silicate is approximately threefold of the neat elastomer.

Mechanical and morphological properties of wood plastic composites based on municipal plastic waste

AbstractProduction and characterization of wood plastic composites (WPC) from the light fraction of municipal plastic wastes (post‐consumer) and wood processing residues (sawdust) were investigated. Composition analysis revealed the presence of polyethylene (PE) and polypropylene (PP) as the two main components of the matrix. In order to improve compatibility and adhesion between all the phases, an ethylene–octene copolymer was used to compatibilize the polymer phases and was also acting as an impact modifier, while the addition of maleated polyethylene and maleated polypropylene (MAPP) were acting as coupling agents between the polymer matrix and the wood flour. The combined effect of all the components was found to produce composites with interesting morphological (dispersion and adhesion) and mechanical properties (tension, torsion, flexion, and impact) after optimization of the additive package (blend of coupling agents). POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

Nanofiller Reinforced Polyolefin Elastomer: Effect on Morphology and Mechanical Properties of Composites

The effect of different types of fillers on morphology and mechanical properties of polymer nanocomposites has been investigated using ethylene-1–octene copolymer (EOC), a polyolefin based elastomer, as matrix and various nanofillers {such as multi-walled carbon nanotubes (MWCNT), layered silicate (LS) and boehmite (OS2)}. The morphological structures were studied by scanning electron microscopy (SEM) while the mechanical properties were characterized by tensile testing and microindentation hardness measurements. It has been shown that the nature of the nanofiller may have significant influence on the mechanical properties of the samples. Among the nanocomposites studied so far, the MWCNT filled samples showed the highest reinforcing effect followed by layered silicate. The least reinforcing effect was obtained for the samples filled with boehmite nanoparticles. Nepal Journal of Science and Technology Vol. 13, No. 2 (2012) 103-108 DOI: http://dx.doi.org/10.3126/njst.v13i2.7721

Foaming behavior of microcellular thermoplastic olefin blends

The influence of reactive compatibilization on the foaming behavior of thermoplastic olefin blends of polypropylene and a metallocene-catalyzed ethylene octene copolymer was investigated. A batch setup was used to foam the samples using carbon dioxide as blowing agent. Solubility measurements were performed to determine the relative amount of gas concentration in the pressurized polymers before foaming. A microscopic method based on the back-scattered electron imaging technique was used to determine the respective locations of the bubbles and the dispersed elastomeric domains in the polypropylene matrix. It was shown that the bubbles are preferentially formed in the dispersed elastomeric domains. A clear relationship was established between the microstructure of the blends prepared with different levels of compatibilizer and the final cellular morphology of the microcellular thermoplastic olefin foams. The initial morphology of the blends was also altered by quiescent coarsening as well as shear-induced phase coalescence, and the impact of the morphological transitions on the cellular structure of the resulting foams was investigated. Dynamic shear and transient measurements of elongation were performed to characterize the viscoelastic behavior of the thermoplastic olefins. It was shown that the addition of a compatibilizer resulted in enhanced viscoelastic properties at low frequencies as well as increased levels of strain hardening, especially at low strain rates. The reactive compatibilization could significantly improve the melt foamability through control of the blend microstructure as well as enhancement of the melt rheological properties.

Structural Evolution of Ethylene–Octene Copolymers upon Stretching and Unloading

Structural evolution of two ethylene-octene copolymers with different octene content during tensile deformation and recovery was investigated using the in-situ synchrotron small-angle X-ray scattering technique. Sample containing 4 mol % octene shows similar deformation mechanism as observed previously that the whole process of deformation can be regarded as a stretching of two interpenetrating networks of crystalline rigid network and entangled amorphous phase. A transition from a crystalline rigid network dominating behavior at small deformations to a stretching-induced crystalline block disaggregation-recrystallization process occurs at a critical strain where stress generated by the stretched amorphous network reaches a critical value leading to the destruction of crystalline blocks. In sample containing 8 mol % octene, this critical strain is much larger than observed in the other sample. Such a phenomenon is attributed to the fact that only crystalline lamellar stacks and bundle-like crystals with much weakened coupling can be developed in the sample. The weakened coupling between crystalline lamellar stacks is due to the existence of interstack amorphous phase which also leads to an inhomogeneous strain distribution in the system.

Effect of Ketuki Fiber on Morphology and Mechanical Properties of Thermoplastics Composites

Different amount of raw Ketuki powder (average diameter: 60 – 120 ?m) was mixed with the thermoplastic polymers such as ethylene-1–octene copolymer (EOC) and isotactic polypropylene (iPP). The melt mixing was performed using an internal mixture and resulting composites were studied for the effect on morphology and mechanical behavior using electron microscopy, tensile testing and thermogravimetric analysis (TGA). The microscopic results showed that the polymer matrix is not compatible with filler resulting in worsening of mechanical properties especially in case of the iPP-based composites. For the EOC composites the rubbery nature of the matrix material remains still visible. The TGA analysis revealed slightly worsened thermal stability of composites, while tensile properties were found to be deteriorated as well. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 73-79 DOI: http://dx.doi.org/10.3126/njst.v13i1.7444

Effect of Organic Montmorillonite on the Cellular Structure and Mechanical Properties of POE/EVA/OMMT Nanocomposite Foams

Nanocomposite foams based-on ethylene octene copolymer (POE)/ethylene vinyl acetate (EVA) copolymer were prepared by melting of POE/EVA with organic montmorillonite (OMMT) by pressurized curing at high temperature. The cellular microstructure of the foamed samples was observed by scanning electron microscope. The effects of OMMT on the cellular structure and mechanical properties of the POE/EVA/OMMT nanocomposite foams were investigated. It was found that OMMT played an important role in affecting the microstructure. Comparing with POE/EVA foam the nanocomposite foams with the addition of 1-3 phr OMMT showed smaller cell size and the structure uniformity of foams was improved. The density of POE/EVA/OMMT nanocomposite samples was lower obviously, meanwhile the mechanical properties of the foamed samples was enhanced.

The influence of synergistic effects of hexakis (4-nitrophenoxy) cyclotriphosphazene and POE-g-MA on anti-dripping and flame retardancy of PET

In this report, hexakis (4-nitrophenoxy) cyclotriphosphazene (HNCP) and ethylene–octene copolymer grafted-maleic anhydride (POE-g-MA) were blended with pure PET together. The fire retardant ability and thermal stability of PET/HNCP/POE-g-MA were investigated respectively. The results indicated that HNCP and POE-g-MA had a synergic effect on the dripping resistance of PET besides the enhancement in flame retardancy to a certain degree. LOI values of the polymers with both POE-g-MA and 10wt%HNCP were higher than that of pure PET and no drips just containing 1wt%POE-g-MA. The reason was that HNCP could be well dispersed in PET when POE-g-MA was added, forming a more effective char layer and preventing dripping of polymers. Indeed, the morphology of charred residue of PET/HNCP/POE-g-MA showed that a porous protective layer with a dense surface was formed. The thermogravimetric analysis revealed that addition of HNCP improved the thermal stability and the yield of char residue of the PET/POE-g-MA systems. Based on a series of experiment results, the synergistic effect of HNCP and POE-g-MA on the anti-dripping of PET was also discussed. In the PET/HNCP/POE-g-MA system, POE-g-MA played a role of compatibilizer. The improved compatibility and dispersion provided the composite with the ideal flame retardancy, thermal stability and anti-dripping property.

Effects of ethylene octene copolymer and ultrafine wollastonite on the properties and morphology of polypropylene-based composites

The mechanical and thermal properties of polypropylene (PP)/ethylene octene copolymer (EOC)/wollastonite composites were investigated as a function of their composition in comparison to PP/EOC blends and native PP. PP was melt mixed with two loadings of EOC (20 and 30% (w/w)); and for the composites, each of these were mixed with three loadings of wollastonite (10, 20 and 30 parts by weight per hundred of the PP/EOC resin) on a twin-screw extruder and then injection molded. Both PP/EOC blends provided a higher elongation at break and impact strength but a lower tensile strength and modulus, storage modulus and flexural strength and modulus when compared with those of the neat PP. The addition of ultrafine wollastonite (particle size of 1200 mesh) into the blends increased the tensile modulus, storage modulus, flexural strength and modulus and impact strength in a dose-dependent manner. Thus, the combined use of EOC and wollastonite can provide balanced mechanical properties to PP. Moreover, thermogravimetric analysis showed that although the degradation temperatures of the composites were not improved, the char formation was remarkably increased with increasing wollastonite loadings.