Octene Copolymer Research Articles

Morphology, crystalline features, and tensile properties of syndiotactic polypropylene blends

ABSTRACTSyndiotactic polypropylene (sPP) was modified with ethylene–octene copolymer (EOC) and ethylene–propylene rubber (EPR), with test samples prepared in a twin‐screw extruder and then injection‐molded. The phase morphology, rheology, and thermal and tensile properties of the modified sPP were investigated. Atomic force microscopy studies showed how the phase morphology of the sPP blends with elastomers depended on the blend compositions, and the results compared with the storage modulus at low frequency. EOC and EPR were dispersed phase in an sPP matrix with spherical shapes when the dispersed content was 20 wt % or lower. The phase cocontinuity started around 40 wt % EOC for the sPP–EOC blends and around 60 wt % EPR for the sPP–EPR. The dispersed phase then formed more complex elongated shapes. The rheological and thermal properties were affected by the sPP–elastomer interphase. EOC promoted the crystallization of sPP; this increased the crystallization temperature and rate. In contrast, EPR had the opposite effect on the crystallization behavior, and the results indicate that sPP and EPR were not completely separated. The tensile properties were studied from −20 to 100 °C. We found that the tensile properties at low temperature could be improved without a loss in high‐temperature properties. In the particular case of 20 wt % EOC, both the strain at yield and strain at break of the sPP–EOC blend were improved at both −20 and 100 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44611.

Exploring the influence of co-monomer content in the dry crosslinked ethylene octene copolymer based blends

This article illustrates the influence of co-monomer content in the ethylene octene copolymer (EOC) on the dry curing process of EOC:PDMS rubber blends. The EOC:PDMS blends were prepared by melt mixing in an internal mixer and crosslinked through electron beam radiation method. During electron beam irradiation both the EOC and PDMS phase gets crosslinked; which is evident from the gel content study. From the rheology analysis, it is understood that the EOC with high octene (co-monomer) content has better radiation crosslinkability as compared with the EOC with low co-monomer content. Through radiation crosslinking, the physico-mechanical properties of the EOC:PDMS system was improved significantly. The tensile strength of high co-monomer content EOC:PDMS 70:30 blends were drastically improved by 49.5% on irradiation with a dosage of 75 kGy. Morphology study of the EOC:PDMS system were carried out by scanning electron microscopy (SEM) and correlated with the physico-mechanical properties. The radiation crosslinked blends shows higher volume resistivity, lower dielectric constant, and loss as compared with the uncrosslinked counterparts. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Radiation crosslinked Polyolefinic blends: exploring thermally tuned dual Shape Memory character

Shape memory behavior of thermally triggered polymeric materials based on ethylene octene copolymer (EOC) and ethylene propylene diene rubber (EPDM) has been studied in details. Investigation of the shape memory behavior of uncrosslinked EOC–EPDM and electron beam crosslinked EOC–EPDM blends have been pursued thoroughly. Shape memory study has been carried out at 60°C, which shows that with the effect of electron beam radiation shape fixity behavior of the crosslinked blends becomes poor as compared with its uncrosslinked blend system whereas the improvement in shape recovery behavior takes place after the exposure to electron beam radiation. Morphology study by Atomic Force Microscopy (AFM) and crystallinity study by X-ray diffraction analysis also give the clear idea regarding the formation of crosslinked network structure. Improvement in gel content with increasing radiation dose supports the formation of network structure. Even after the crosslinking in presence of electron beam radiation also, it has been found that crosslinked EPDM rich blends is superior in terms of shape memory behavior point of view. Lower decay of stress value coupled with lower relaxation ratio of crosslinked EPDM rich blend support its superior shape memory behavior. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of Octene Level in EOC–PDMS Thermoplastic Vulcanizates for Cable Insulation Applications

ABSTRACTThermoplastic vulcanizates are prepared by blending ethylene–octene copolymer with polydimethylsiloxane rubber and dynamically cross-linking with dicumyl peroxide. From moving disc rheometer study, it is found that, as the octene content increases, the cross-linking efficiency of the peroxide to cross-link that particular ethylene–octene copolymer decreases. For ethylene–octene copolymer 8445 thermoplastic vulcanizates, as the blend composition changes from 50:50 to 80:20 ethylene–octene copolymer:polydimethylsiloxane, there is 116% increase in tensile strength which is correlated with the morphology study by atomic force microscopy. All the different ethylene–octene copolymer:polydimethylsiloxane thermoplastic vulcanizates exhibited lower dielectric constant and higher electrical resistivity which makes it suitable for the cable insulating applications.

Joint Effect of Poly(ethyhlene‐co‐1‐octene) Chain Length and 1‐Octene Fraction on High‐Temperature Thermal Gradient Interaction Chromatography

High‐temperature thermal gradient interaction chromatography (HT‐TGIC) fractionates polyolefins based on an adsorption–desorption mechanism. Several factors influence the shape and position of HT‐TGIC chromatograms, notably polymer microstructure, analytical conditions, and, to a lesser extent, solvent type. This article investigates the joint influence of chain length and comonomer content of a series of polyethylene and ethylene/1‐octene copolymers having similar 1‐octene fractions (0–13 mol%) and a wide range of molecular weights on HT‐TGIC fractionation. For each series of copolymers having similar 1‐octene fraction, the elution peak temperature decreases exponentially and the profiles become increasingly broader below a critical number average chain length value. The authors use Monte Carlo simulation and Stockmayer distribution to explain the observed behavior, finding that no simple correlation exists between ethylene sequences in the copolymers and peak elution temperature, but that there is strong evidence that axial dispersion is responsible for symmetrical broadening of the HT‐TGIC profiles. The authors also study the HT‐TGIC of binary blends, finding that components with similar 1‐octene contents and dissimilar chain lengths tend to increase co‐adsorption/co‐desorption effects. image

EFFECT OF ELECTRON BEAM IRRADIATION ON THE STRUCTURE–PROPERTY RELATIONSHIP OF ETHYLENE OCTENE COPOLYMER AND POLYDIMETHYL SILOXANE RUBBER BLENDS

ABSTRACT The effects of electron beam irradiation on the structure–property relationship of blends can be studied based on ethylene octene copolymer (EOC) and polydimethyl siloxane (PDMS) rubber at three different blend ratios prepared with a melt mixing technique. Irradiation with 2.5 MeV electron beam accelerating energy, over a radiation dose varying from 25 to 150 kGy, causes cross-linking in both the EOC and the PDMS phases. However, cross-linking of the EOC phase without affecting the crystallinity of the EOC polymer leads to tremendous improvement in the physicomechanical properties, including the tensile strength, which improves by nearly 35% for 70:30 EOC:PDMS blends. Morphology of the blends before and after irradiation can be analyzed by scanning electron microscopy and atomic force microscopy and correlated with the physicomechanical properties. The physicomechanical properties of the individual polymer components after irradiation show that radiation cross-linking is more effective for PDMS rubber than it is for EOC. However, at higher radiation doses, chain scissions are possible in both EOC and PDMS rubber, which affect the physicomechanical properties. Through blending and subsequent radiation cross-linking, the maximum degradation temperature of EOC can be increased from 488.6 to 512.8 °C.

Exploring the effect of radiation crosslinking on the physico‐mechanical, dynamic mechanical and dielectric properties of EOC–PDMS blends for cable insulation applications

This work focuses on the effect of electron beam irradiation on the physico‐mechanical, dynamic mechanical and dielectric properties of blends based on ethylene octene copolymer (EOC) and poly dimethyl siloxane (PDMS) rubber. It is found that electron beam irradiation caused considerable improvement in the physico‐mechanical properties; the tensile strength was enhanced by nearly 35% for 70:30 EOC:PDMS blend. Phase morphology of the blends analyzed before irradiation by scanning electron microscopy (SEM) exhibited droplet/matrix morphology with sizes of the PDMS rubber domain varying from 0.55 µm to 0.47 µm as the amount of PDMS rubber decreased from 30 wt% to 10 wt%. This reduction in the PDMS rubber domain has been correlated with the physico‐mechanical properties of the blends. Further, the dynamic mechanical properties and creep behavior of these EOC:PDMS blends before and after irradiation has been studied. It is inferred that the 70:30 blend after radiation crosslinking shows a 17% decrease in the creep compliance, i.e. higher creep resistance compared to neat blends. All the radiation crosslinked blends exhibited lower dielectric constant, lower dielectric loss and higher electrical resistivity as compared to the virgin blends which makes it suitable for cable insulating application. Copyright © 2016 John Wiley & Sons, Ltd.

The contribution of various network knots during the deformation of ethylene copolymers and nanocomposites based on them

An analysis of the deformation mechanism and changes in mechanical parameters of low-crystallinity ethylene–octene copolymers of various densities and modified with detonation nanodiamonds is performed through the use of models based on the statistical theory of rubber-like elasticity. Experimental data were processed in terms of the Haward model with allowance for the non-Gaussian statistics of macromolecules at high strain and limited extensibility and the so-called “slip-link” model, which considers the density of labile knots and permanent entanglements. Despite obvious simplifications, both models attribute the discovered extrema of the concentration dependences of mechanical properties at low concentrations of nanodiamonds to the change in the number of segments between network knots and the following change in elastic modulus (Haward model) or to the number of labile and permanent knots (“slip-link” model), a circumstance that verifies the nucleating effect of nanodiamonds. It was found that the relative increase in density of each type of knot significantly depends on the degree of crystallinity of the matrix and the concentration of the modifier. Deformation calorimetry showed that tensile and cyclic loading of the investigated systems are followed by changes in internal energy. The roles of its intramolecular and intermolecular components at the various stages of deformation and the causes of their changes were estimated. The correlation between energy effects and the transformation of the structuring and parameters of the used models was determined.

High-temperature study of radiation cross-linked ethylene–octene copolymers

Three ethylene–octene copolymers (EOC) with a wide range of octene content (17, 30, and 38 wt%) and with the same melt flow index of 1 g/10 min were cross-linked by e-beam radiation (in range 30–120 kGy). The testing methods comprised of rheology, a high-temperature creep test, an analysis of the gel content, and a dynamic mechanical analysis (DMA) test. It was discovered that copolymers with a high octene content attain a higher level of cross-linking density. Cross-linking influenced properties below T m only marginally as seen from the DMA results. However, the properties above T m were highly influenced as detected by high-temperature creep and rheology. Above T m, without the presence of crystals, only the chemical bonds holding the amorphous chains together manifested a gradually decreasing creep at 150 °C with an increasing irradiation level. The loss factor (tanδ at 0.1 Hz) at 150 °C revealed a decreasing trend (or higher cross-linking level) with an increasing octene content. High-temperature results were supported by an increasing gel content with increasing octene content. Samples irradiated to 30 kGy dissolved completely in xylene but showed significantly changed rheological characteristics indicating only an increase in the molecular weight and branching. Analysis according to the Charlesby–Pinner equation revealed increased cross-linking to the scission ratio G(X)/G(S) for EOCs with a higher octene content. While the q 0 value which relates to cross-linking changed only slightly, a significant decrease in the p 0 value which relates to chain scission was discovered.

Rheological and morphological properties of thermoplastic olefin blends containing nanosilica

This study aims at understanding the rheological and morphological behavior of polypropylene (PP) and ethylene octene copolymer (EC) blends containing nanosilica. Maleic anhydride grafted species of PP and EC were also used to favor the localization of the silica particles in the matrix or in the dispersed phase, respectively. The morphological stability of the blends under flow was investigated by shearing at a very low shear rate of 0.01s−1. The morphology of the dispersed polymer phases as well as the microstructure of the silica particles inside the nanocomposites were examined using scanning and transmission electron microscopy techniques. Considering the limited time stability of composites with high level of silica loading, the low frequency data of these systems were obtained using dynamic frequency sweep data as well as an extended set of transient creep data reflecting the long time relaxation behavior. The presence of silica particles resulted in an improved morphological stability of all nanocomposites, but the effect was more pronounced when the nanoparticles were localized in the dispersed EC phase. While shearing diminished the viscoelastic properties of the blends containing no silica particle, the sheared nanocomposites with a high concentration of nanosilica revealed enhanced levels of viscoelasticity. This was attributed to the promoted interconnection of solid particles during shearing and the formation of more extended networks as confirmed by microscopic observations.

Rheological, morphological and mechanical investigations on ethylene octene copolymer toughened polypropylene prepared by continuous electron induced reactive processing

EOC toughened PP with increased interfacial adhesion due to EOC–PP grafting was prepared by continuous EIReP and in continuation the rheological, morphological and mechanical properties of EOC toughened samples were investigated.

Impact of non-functionalized and ionic liquid modified carbon nanotubes on mechanical and thermal properties of ethylene- octene copolymer nanocomposites

In this article the development and characterization of composites made from metallocene based ethylene-octene copolymer (EOC) with 38% octene content, non-modified or modified multi walled carbon nanotubes (MWCNTs), covalently functionalised with long chain hexadecyl moiety imidazolium ionic liquid (IL-f-MWCNTs), is presented. The procedure of MWCNTs functionalization is discussed. In order to obtain a good dispersion of the filler, composites with MWCNTs and IL-f-MWCNTs in the concentration range of 0.5-12 wt.% were made by ultrasonication / thermoplastic mixing method. The results indicated improvement in mechanical properties with increase of the filler content. The methodology of the development of EOC matrix nanocomposites with IL-f-MWCNTs showed advantages of the conductive material creation with high mechanical stiffness compared to direct melt mixing of EOC with non-modified MWCNTs. A notable enhancement of thermal stability was observed in case of both pristine MWCNTs and IL-f-MWCNTs containing EOC nanocomposites, which was attributed to scavenging action of the nanofiller. Modification of EOC with IL-f-MWCNTs showed somewhat increased efficiency in enhancing overall thermal stability of the composites because of better dispersion of the nanofiller due to compatibilizing effect of IL modifier.

Structures and properties of low-crystallinity polyolefins modified with nanodiamonds

To search for new methods of governing the structures and properties of low-crystallinity ethylene–octene copolymers with densities of 0.861 and 0.885 g/cm3, the effect of small additives of diamond-like nanoparticles on the mechanical properties and structuring processes in these elastomers is studied. It is shown that nanodiamonds are distributed sufficiently well in the matrixes of the copolymers and improve the stress–strain characteristics even at a low content of nanoparticles. The influence of the functional composition of the modifier surface, the preparation method and thermal prehistory of the composites, and the degree of crystallinity of the elastomer matrix on the structure and properties of the nanocomposites is investigated. The copolymers contain a hexagonal mesophase and orthorhombic crystallites, with their amount in the composites being higher. The efficiency of nanomodifiers in the matrix with a higher crystallinity is noticeably lower. Aerosils rank much below nanodiamonds in terms of efficiency, especially in the low-concentration range. The pattern of deformation dependences of thermodynamic parameters is similar to that of typical thermoplastic elastomers. The effect of nanoparticles on the thermomechanical behavior of the copolymers depends on both the modifier amount and the degree of crystallinity of the matrix.

Dynamic mechanical properties, crystallization behaviors, and low‐temperature performance of polypropylene random copolymer composites

ABSTRACTIn this study, polypropylene random copolymer (PPR) composites were prepared by the addition of either three kinds of thermoplastic rubber (TPR) modifiers (types 2088A, 2095, and 2096) or an ethylene–octene copolymer (POE)/high‐density polyethylene (HDPE; 2 :1 w/w) blend. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and dynamic mechanical analysis were used to characterize the crystallization behaviors and dynamic mechanical properties of the PPR composites. The results indicated that PPR/POE/HDPE and PPR/TPR2088A had better comprehensive mechanical properties, especially the low‐temperature toughness among all of the samples. The obtained PPR/POE/HDPE blends showed a high toughness and good stiffness in the temperature interval from −10 to 23°C with the addition of only 10 wt % POE/HDPE. When the temperature continued to fall below −10°C, the PPR/TPR2088A composites exhibited a better impact toughness without a loss of too much stiffness. The good low‐temperature toughness of those two composites was attributed to both the decrease in the crystallinity and the uniform dispersion, obvious interfacial adhesion, and cavitation ability of POE/HDPE and TPR2088A in the PPR matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42960.

Thermo-responsive shape memory polymer blends based on alpha olefin and ethylene propylene diene rubber

Thermally stimulated novel shape memory polymer blend of ethylene octene copolymer (EOC) and ethylene propylene diene terpolymer (EPDM) has been developed. This novel polyolefinic blends possess superior shape memory behaviour in presence of heat. Shape memory behaviour study at 60 °C of the blends shows that the blends containing higher fraction of EPDM exhibits superior shape memory behaviour in terms of shape fixity (f) and shape recovery ratio (RR). Structural similarities of the pristine components lead to higher degree of compatibility which also results better physicomechanical behaviour. Lower modulus value followed by low relaxation ratio of the blend containing higher proportion of EPDM also supports the superior shape memory behaviour of the EPDM rich blend. Thus EPDM rich blend shows better shape memory effect among the various blends.

High Temperature Thermal Gradient Interaction Chromatography (HT‐TGIC) of Ethylene/1‐Octene Copolymers: Model Development and Validation

SummaryHigh temperature thermal gradient interaction chromatography (HT‐TGIC) is a new polymer characterization technique developed to characterize the chemical composition distribution (CCD) of ethylene/1‐olefin copolymers based on interactions between polymer chains and the graphitic surface. In this work, a mathematical model was developed to describe HT‐TGIC fractionation using population balances and a non‐equilibrium, multi‐stage adsorption/desorption model. The proposed model was validated with HT‐TGIC experimental profiles of ethylene/1‐octene copolymers with various comonomer contents. Good agreement between experiments and model results was observed.

Effect of Column Type on Polyolefin Fractionation by High‐Temperature Thermal Gradient Interaction Chromatography

SummaryHigh‐temperature thermal gradient interaction chromatography (HT‐TGIC) can be used to measure the chemical composition distribution (CCD) of semi‐crystalline and amorphous polyolefins. HT‐TGIC extends the range of polyolefin chemical compositions that can be measured today with crystallization‐based techniques. Hypercarb® columns packed with porous graphitic carbon are commonly used as the stationary phase in HT‐TGIC fractionation. We used a set of ethylene/1‐octene copolymers having different comonomer fractions (up to 25% of 1‐octene) and approximately the same molecular weight average to investigate how commercial Hypercarb® columns with distinct lengths and particle sizes affected HT‐TGIC fractionation. Binary copolymer blends were also analyzed to study how different blend compositions affected HT‐TGIC peak positions and shapes.

Investigation into the structure–property relationship and technical properties of TPEs and TPVs derived from ethylene octene copolymer (EOC) and polydimethyl siloxane (PDMS) rubber blends

This work focuses on the study of thermoplastic vulcanizates based on ethylene octene copolymer (EOC) and poly dimethyl siloxane (PDMS) rubber prepared by melt mixing technique using dicumyl peroxide (DCP). It is found that the addition of peroxide causes crosslinking in both the phases. However, crosslinking without affecting the crystallinity of the EOC polymer leads to tremendous improvement in the mechanical properties, including the tensile strength which has improved by nearly 60%. For better understanding about the crosslinking characteristics of thermoplastic vulcanizates (TPVs), significant correlation has been made between the vulcanized network and the physico-mechanical properties. Further, the dynamic mechanical properties and creep behavior of these thermoplastic elastomers (TPEs) and TPVs have also been studied. It is inferred that the TPVs show a 19% decrease in the creep compliance, i.e. higher creep resistance compared to uncrosslinked blends. Subsequently, the morphology of the blends before and after vulcanization shows a decrease in the spherical PDMS domains from 0.8 μm to > 0.4 μm. Ageing and reprocessing studies of the prepared TPVs also show better physico-mechanical properties even after reprocessing twice. Thus, the prepared TPVs may have tremendous applications in automobile sectors.

Crystallization behavior and mechanical properties of copolymers of isotactic poly(1-butene) with 1-octene from metallocene catalysts

The crystallization behavior and the mechanical properties of random isotactic butene–octene copolymers (iPBC8) prepared with a metallocene catalyst are presented. Samples with low octene concentrations, up to nearly 6 mol%, crystallize from the melt in form II. In these samples octene units stabilize the tetragonal form II, decelerating or even preventing the transformation of form II into the trigonal form I. Octene concentrations higher than 7 mol% prevent crystallization of the samples from the melt and the obtained amorphous samples crystallize by aging at room temperature in mixtures of form II and form I'. The sample with the highest octene concentration of 11.5 mol% crystallizes surprisingly from the amorphous phase directly in the pure form I'. In these samples, form I' crystallized from the amorphous phase transforms into form II by stretching. Form II transforms back into form I' upon releasing the tension. Therefore, in samples where form I' is favored in powder samples, form II is favored in stretched fibers. The transformation of form I into form II by stretching and the back transformation of form II into form I after releasing the tension is unusual for isotactic polybutene (iPB) and rather unexpected. The presence of octene comonomer units also affects the mechanical behavior of iPB and produces increase of flexibility and ductility with increasing comonomer content, and samples with octene concentration higher than 6–7 mol% show unexpected remarkable elastomeric properties. The formation of crystals of form II or form I' during aging allows development of elastomeric properties and enhancement of mechanical strength. The elastic properties are associated to the reversible crystal–crystal phase transition between form II and form I occurring during stretching and when the tension is removed.

Compatibilization efficiency in post-consumer recycled polyethylene/polypropylene blends: Effect of contamination

This work investigates the effect of ethylene–octene copolymer (EOC) as a compatibilizer for two virgin and two recycled polyethylene/polypropylene blends. In particular, a focus is made on the interfering effects of contamination in recycled materials. Scanning electron microscopy (SEM) shows that (i) recycled compounds have smaller domain sizes than virgin compounds, and (ii) addition of a compatibilizer is much more effective on domain sizes reduction in virgin compounds than in recycled ones. Conversely, transmission electron microscopy, coupled with energy dispersive X-ray spectroscopy, shows the presence of nano-size contaminants in both recycled blends. Such contaminants are considered responsible for the above mentioned observations in SEM. Mechanical characterizations are also in good agreement with morphological observations. Although recycled compounds containing EOC show improved deformability, the ultimate deformation of virgin compounds is much higher. POLYM. ENG. SCI., 55:2368–2376, 2015. © 2015 Society of Plastics Engineers