Mechanical,rheological, thermal,and morphological properties of blends based on poly(propylene)/poly(propylene‐co‐1‐octene)/poly(ethylene‐co‐1‐octene)

The effect of addition of propylene copolymer, produced by metallocene catalysts, on the mechanical, rheological, and morphological properties of blends based on poly(propylene) (PP) and ethylene–1‐octene copolymer (EOC) was evaluated. It was observed that the addition of 2 wt % propylene–1‐octene copolymer (POC) improved the impact strength of the EOC/PP blends. The rheological analysis indicated that the addition of propylene copolymer produced materials with improved processability. Thermal and morphological analysis showed that the POC acts as a compatibilizer on the EOC/PP blends. © 2003 Wiley Periodicals, J Appl Polym Sci 89: 1690–1695, 2003     

Evaluation of toughening mechanisms of polypropylene/ethylene–octene copolymer/maleic anhydride‐grafted poly(ethylene‐co‐octene)/clay nanocomposite

The toughness of a polypropylene (PP)/ethylene‐octene copolymer (EOC)/maleic anhydride‐grafted poly(ethylene‐co‐octene) (EOC‐g‐MA)/clay nanocomposite and blends of PP/EOC and PP/EOC/EOC‐g‐MA was investigated using Charpy impact and single‐edge‐notch tensile (SENT) tests. In order to understand the toughening mechanisms, impact fracture surfaces and damage zones of single‐edge‐notch samples were studied with scanning electron microscopy and transmission optical microscopy, respectively. It was observed that the addition of EOC‐g‐MA to PP/EOC blend led to improvements in both impact strength and fracture energy of SENT tests because of the enhanced compatibility of the blend, which resulted from reduced EOC particle size and improved interfacial adhesion, and the decreased crystallinity of PP. The incorporation of clay to PP/EOC/EOC‐g‐MA blend caused a further increase of the toughness, owing to the greater decrease in the size of elastomer particles, to the presence of clay tactoids inside the elastomer phase and presumably to debonding of clay layers during the low‐speed SENT tests. The results of microscopic observations showed that the main toughening mechanism in PP/EOC/EOC‐g‐MA blend and PP/EOC/EOC‐g‐MA/clay nanocomposite is crazing. Copyright © 2012 Society of Chemical Industry     

Crystallization behavior and mechanical properties of polypropylene random copolymer/poly(ethylene‐octene) blends

New polymer blends of polypropylene random copolymer (PP‐R) and poly(ethylene‐octene) (POE) were prepared by melt‐blending process using a corotating twin‐screw extruder. The POE content was varied up to 35%. The toughening efficiency of POE for PP‐R was evaluated by the mechanical properties of the resulted PP‐R/POE blends. The crystallization behavior and morphology of the blends were also studied. Results show that POE acts as nucleation agent to induce the crystallization of PP‐R matrix at higher crystallization temperature. Super‐toughened PP‐R/POE blends (Izod impact strength more than 500 J/m) can be readily achieved with only 10 wt % of POE. The high toughness of PP‐R/POE is attributed to cavitation and shear yielding of matrix PP‐R, as revealed by the morphology studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rheological and thermal properties of binary blends of polypropylene and poly(ethylene‐CO‐1‐octene)

Dynamic viscoelastic properties of binary blends consisting of an isotactic polypropylene (i‐PP) and ethylene‐1‐octene copolymer (PEE) were investigated to reveal the relation between miscibility in the molten state and the morphology in the solid state. In this study, PEE with 24 wt % of 1‐octene was employed. The PEE/PP blend with high PEE contents showed two separate glass‐relaxation processes associated with those of the pure components. These findings indicate that the blend presents a two‐phase morphology in the solid state as well as in the molten state. The PEE/PP blend with low PEE content showed a single glass‐relaxation process, indicating that PEE molecules were probably incorporated in the amorphous region of i‐PP in the solid state. The DMTA analysis showed that the blends with low PEE contents presented only one dispersion peak, indicating a certain degree of miscibility between the components of these blends. These results are in accordance with the results of the rheological analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1634–1639, 2001     

Rubber‐toughened polypropylene nanocomposite: Effect of polyethylene octene copolymer on mechanical properties and phase morphology

Rubber‐toughened polypropylene (PP)/org‐Montmorillonite (org‐MMT) nanocomposite with polyethylene octene (POE) copolymer were compounded in a twin‐screw extruder at 230°C and injection‐molded. The POE used had 25 wt % 1‐octene content and the weight fraction of POE in the blend was varied in the range of 0–20 wt %. X‐ray diffraction analysis (XRD) revealed that an intercalation org‐MMT silicate layer structure was formed in rubber‐toughened polypropylene nanocomposites (RTPPNC). Izod impact measurements indicated that the addition of POE led to a significant improvement in the impact strength of the RTPPNC, from 6.2 kJ/m² in untoughened PP nanocomposites to 17.8 kJ/m² in RTPPNC containing 20 wt % POE. This shows that the POE elastomer was very effective in converting brittle PP nanocomposites into tough nanocomposites. However, the Young's modulus, tensile strength, flexural modulus, and flexural strength of the blends decreased with respect to the PP nanocomposites, as the weight fraction of POE was increased to 20 wt %. Scanning electron microscopy (SEM) was used for the investigation of the phase morphology and rubber particles size. SEM study revealed a two‐phase morphology where POE, as droplets was dispersed finely and uniformly in the PP matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3441–3450, 2006     

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., 57:1016–1027, 2017. © 2016 Society of Plastics Engineers     

Supertoughness in Polysulfone/Poly(ethylene‐octene) Blends

Summary: Poly(sulfone of Bisphenol A) (PSU) based blends were obtained by melt blending PSU with up to 15 wt.‐% poly(ethylene‐octene) either modified with maleic anhydride (mPEO) or not (PEO). The dispersed particle size was small and similar in blends with PEO or mPEO. These facts indicated respectively that the interfacial tension was low and the lack of compatibilizing effect of mPEO. Some preferential presence of PEO in the outer surface of the specimens was observed, and was attributed to the large viscosity difference between the two components of the blends. This had no effect on the modulus of elasticity, but speeded up both the yield stress and ductility decreases at rubber contents above 3.25 wt.‐%. However, despite the immiscibility of the components, and thanks to the small particle size of the blends, super‐toughness was attained in the unmodified PSU/PEO blends. This was at PEO contents (3.25 wt.‐%) at which the modulus, yield stress and ductility of the blends were almost as good as those of pure PSU. It appeared that a change of the chemical nature of the rubber did not influence by itself super‐toughness, unless it was accompanied by either a morphological or adhesion change.

Impact strength of PSU‐based blends vs. PEO (○) or mPEO (?) content.     

Dynamic‐mechanical and thermal characterization of polypropylene/ethylene–octene copolymer blend

Polypropylene/Ethylene–Octene copolymer (PP/EOC) blends were prepared by melt blending technique followed by compression molding. The effect of addition of EOC on the mechanical behavior of the PP matrix was investigated. Tensile and flexural strengths decreased with the incorporation of EOC. However, the impact strength of the matrix polymer increased in all the blend systems. The blends prepared at 30% EOC content showed an increase in the impact strength to the tune of 380% as compared with polypropylene (PP) matrix. The morphology of the fractured surfaces was investigated employing Scanning Electron Microscopy. SEM micrographs depicted the formation of biphase structure, wherein the EOC phases were homogeneously dispersed as small droplets within the PP matrix. WAXD patterns revealed that the α monoclinic form of isotactic PP does not show any significant change with the incorporation of EOC up to 70 wt %. DSC thermograms revealed a decrease in the melting temperature of the virgin matrix with the addition of EOC. The blend system at 50% EOC exhibited a broad crystallization exotherm at 75°C thus indicating multiple crystallization behavior primarily attributed to the difference in the nucleation process. Further DMA analysis showed presence of two different relaxation peaks corresponding to the T_g of EOC and PP matrix respectively, confirming the formation of a biphase structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation of toughened polypropylene‐g‐poly(butyl acrylate‐co‐acrylated castor oil) by suspension grafting polymerization

Butyl acrylate (BA) with acrylated castor oil (ACO) was grafted onto porous polypropylene (PP) granules by grafting polymerization. Crosslinked copolymer microdomains which functioned as rubber phase to improve the toughness of PP were filled into the pores of PP granules. The sizes of crosslinked copolymer microdomains were controlled in the range of 0.1–1 μm in PP matrix. The results of fourier transform infrared spectroscopy and scanning electron microscope of PP‐g‐(BA‐co‐ACO) after extracted by acetone confirmed that BA and ACO were grafted onto PP successfully. The effects of comonomer ratio, initiator content and comonomer content on grafting percentage (GP) and grafting efficiency (GE) were investigated. The GP of PP‐g‐(BA‐co‐ACO) could be up to 21.3% with the comonomer content increasing to 25%. The crosslinked copolymer decreased the melting flow index and the relative crystallinity of PP. Dynamic mechanical thermal analysis showed that the glass transition temperature of PP decreased slightly from 22°C to 15°C. The addition of 5% comonomer content led to an increase of notched impact strength from 1.96 to 3.81 kJ/m² (nearly doubled) and a marginal decrease in the tensile strength of PP. Then with further addition of comonomer, the notched impact strength increased to 8.98 kJ/m² while the tensile strength was 29.37 MPa. POLYM. ENG. SCI., 58:86–93, 2018. © 2017 Society of Plastics Engineers     

Morphology and mechanical properties of blends of linear low density polyethylene and poly(ethene‐propene‐1‐butene)

Blends of linear low density polyethylene (LLDPE) and ethene‐propene‐1‐butene copolymer (t‐PP) were obtained through mechanical mixing using a single‐screw extruder with different compositions: 20, 40, 50, 60, and 80 wt % of t‐PP. For this, two types of polyethylene were used: 1‐hexene comonomer and 1‐octene comonomer based. The same blends were prepared in a batch mixer and the torque and temperature were analyzed. The torque showed a decrease with increasing t‐PP content, indicating better processability of the mixture in comparison with LLDPE. The morphology of the blends was analyzed by SEM and showed a composition dependence. The mechanical properties of the blends were evaluated by tensile tests. The results revealed that the best properties were obtained in a 20% t‐PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1255–1261, 2006     

Polypropylene/metallocene ethylene‐octene copolymer blends with a bimodal particle size distribution: Mechanical properties and their controlling factors

Blends of polypropylene homopolymer (PP) and metallocene produced ethylene‐octene copolymer (EOR) with a bimodal particle size distribution were investigated. The aim of the work was to study the influences of EOR characteristics and its concentration on the tensile and impact properties of the blends. The matrix ligament thickness between rubber particles was measured and compared to those predicted using the theoretical models. The relationships between blend morphology and impact property were reported. It was found that the content of comonomer and molecular weight of the EOR as well as its concentration in the blends were the major factors controlling the tensile and impact properties of the blends. These factors became ineffective to impact property when the ligament thickness of the matrix was larger than the critical value (T ～0.3–0.4 μm). To achieve blends of high impact strength, the ligament thickness between rubber particles should be smaller than the critical value, and for a certain ligament thickness, EOR with high octene content and high molecular weight was preferred. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2412–2418, 2002     

Dynamic Mechanical Properties of Poly(propylene) Blends with Poly[ethylene‐co‐(methyl acrylate)]

Summary: Blends of poly(propylene) (PP) were prepared with poly[ethylene‐co‐(methyl acrylate)] (EMA) having 9.0 and 21.5% methyl acrylate comonomer. A similar series of blends were compatibilized by using maleic anhydride grafted PP. The morphology and mechanical properties of the blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) in tensile mode. The DMA method and conditions were optimized for polymer film specimens and are discussed in the experimental section. The DSC results showed separate melting that is indicative of phase‐separated blends, analogous to other PP‐polyethylene blends but with the added polarity of methyl acrylate pendant side groups that may be beneficial for chemical resistance. Heterogeneous nucleation of PP was decreased in the blends because of migration of nuclei into the more polar EMA phase. The crystallinity and peak‐melting temperature did not vary significantly, although the width of the melting endotherm increased in the blends indicating a change had occurred to the crystals. DMA analysis showed the crystal‐crystal slip transition and glass transition (T_g) for PP as well as a T_g of the EMA copolymer occurring chronologically toward lower temperatures. The storage modulus of PP and the blends was generally greater with annealing at 150 °C compared with isothermal crystallization at 130 °C. The storage modulus of the blends for isothermally crystallized PP increased with 5% EMA, then decreased for higher amounts of EMA. Annealing caused a decrease with increasing copolymer content. The extent of the trend was greater for the compatibilized blends. The T_g of the blends varied over a small range, although this change was less for the compatibilized blends.

Storage modulus for PP and EMA9.0 blends annealed at 150 °C.     

Melt‐state miscibility of poly(ethylene‐co‐1‐octene) and linear polyethylene

On purpose to examine the effect of branch length on the miscibility of polyolefin blends, miscibility behavior of linear polyethylene/poly(ethylene‐co‐1‐octene) blend was studied and compared to that of linear polyethylene/poly(ethylene‐co‐1‐butene) blend. Miscibility of the blend was determined by observing the morphology quenched from the melt, and by using the relation between interaction parameter and copolymer composition. When the weight composition and molecular weight was the same, poly(ethylene‐co‐1‐octene) was slightly more miscible with linear polyethylene than poly(ethylene‐co‐1‐butene) was. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Behavior of poly(ethylene‐co‐olefin) polymers as elastomeric materials

The properties of two new ethylene‐α‐olefin copolymers, namely, ethylene–1‐hexene copolymer (EHC) and ethylene–1‐octadecene copolymers (EOC), synthesized via metallocene catalysts were evaluated. The copolymerization was carried out in an autoclave reactor with Et(Indenyl)₂ZrCl₂/methylaluminoxane as a catalyst system. These single‐site catalysts (metallocene type) allow one to obtain very homogeneous copolymers with excellent control of the molecular weight distribution and proportion of comonomer incorporation. So, copolymers with 18 mol % comonomer in the case of EHC and 12 mol % for EOC were shaped, and activities around 100,000 kg of polymer mol^?1 of Zr bar^?1 h^?1 were reached. The properties of these copolymers were compared with other commercial elastomers, such as ethylene–propylene copolymers synthesized by Ziegler–Natta catalysts and an ethylene–octene copolymer obtained via metallocene catalysts. The results show that these new copolymers, in particular, EOC, had excellent elastomeric properties. Furthermore, they had a relatively low viscosity, which implied a good response during processing. Moreover, the effectiveness of these copolymers as impact modifiers for polyolefins was also studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3008–3015, 2004     

Tensile properties and morphological evolution of polypropylene and poly(ethylene‐co‐1‐octene) blends

Extruded sheet of isotactic polypropylene and poly(ethylene‐co‐1‐octene) blends extruded from a counterrotating twin‐screw extruder were studied by scanning electron microscopy, tensile test, and small‐angle X‐ray scattering. The average characteristic length (Λ_m) determined by the statistical computing from the SEM images increases linearly with increasing of dispersed phase concentration. When POE content is 50 wt% (double continuous phase), Λ_m is two or three times as big as that of other blends ratio. The analyses of SAXS data confirm this result. Comparison has been made between experimental data of tensile test and those predicted from several meso‐mechanical models such as parallel model, series model, Halpin's model, Mori‐Tanaka's model, and modified mixture model. The modified mixture model is an effective method for predicting Young's modulus in comparison with other models. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Influence of composition and phase morphology on rheological properties of polypropylene/poly(ethylene‐co‐octene) blends

In this article, the phase morphology and rheological properties of polypropylene (PP)/poly(ethylene‐co‐octene) (POE) blends with a droplet‐matrix microstructure were studied by scanning electron microscopy and rheological experiments. The data were analyzed to yield the variations of rheological behavior with blend composition and insight into the microstructure of PP/POE blends. The Palierne's emulsion type model was used to extract information on rheological properties, and the interfacial tensions between the PP and POE were determined by fitting the experimental data with this model. The results indicated that the interfacial tensions were shown to depend on blend composition and temperature. Rheological properties of PP/POE blends were investigated in a systemic way with varying shear histories. The results showed that shear history had an important effect on the rheological properties of the blends due to the dispersed phase (POE) domains refined with increasing preshear rate and preshear time. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Structure development in melt spinning of poly(ethylene‐co‐octene) filaments with various comonomer contents

An experimental study of the spinnability and the variation in crystallinity and orientation of melt spinning of poly(ethylene‐co‐octene) with different contents of comonomers was carried out. The spinning behavior of these polymers was investigated under different draw‐down ratios and temperatures and correlated to spinline stress. The melt‐spun filaments were characterized by wide‐angle X‐ray diffraction birefringence, and differential scanning calorimetry. S‐1 is a high‐density polyethylene and S‐2, S‐3, and S‐4 have 16, 22, and 38 wt % octene. An orthorhombic unit cell was found in all four polymers, but a dominant hexagonal structure (perhaps mesophase) was found for the highest octene level (S‐4). The orientation factors for the a‐, b‐, and c‐axis of the orthorhombic crystal structure and a‐axis of the hexagonal phase were then calculated. The crystalline orientation behavior of the lower octene copolymers (S‐1, S‐2, and S‐3) are similar and can be represented as a “row‐nucleated“ structure. However, the orientation behavior of S‐4 was different. The uniaxial mechanical properties were also measured. The Young's modulus and tensile strength generally increased with birefringence for all polymers. With increasing content of octene, the Young's modulus showed a decrease from semicrystalline thermoplastic toward an elastomer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 9–22, 2004     

Super‐toughness in compatibilized poly(butylene terephthalate)/poly(ethylene‐octene) copolymer blends

Poly(butylene terephthalate) (PBT)/poly(ethylene‐octene) (PEO) blends containing 1.0 wt% epoxy and from 0 to 30 wt% PEO were obtained by extrusion and injection molding. The blends were composed of two pure amorphous phases. The observed torque increases showed that epoxy reacted with PBT, leading to a fine and homogeneous morphology up to 15 wt% PEO content, which appeared larger and more heterogeneous at higher PEO contents. Toughness values fifteen‐fold those of pure PBT were obtained with only 13 wt% PEO. The tensile properties, including ductility, decreased with increasing PEO content, indicating that the adhesion level necessary for high ductility is higher than that necessary for super‐toughness. The inter‐particle distance (τ) was the main parameter that controlled toughness. The comparison of the results of this work with those of the same PBT/PEO blends with two different compatibilizers provides additional strong evidence of the adhesion at the interphase as the main parameter that controls the critical τ in these modified thermoplastic/rubber blends.     

Properties of soy protein isolate/poly(ethylene‐co‐ethyl acrylate‐co‐maleic anhydride) blends

Blends of soy protein isolate (SPI) with 10, 20, 30, 40, and 50% poly(ethylene‐co‐ethyl acrylate‐co‐maleic anhydride) (PEEAMA), with or without addition of 2.0 wt % methylene diphenyl diisocyanate (MDI), were prepared by mixing with an intensive mixer at 150°C for 5 min, and then milling through a 1‐mm sieve. Blends were then compression‐molded into a tensile bar at 140°C. Thermal and mechanical properties and water absorption of the blends were studied by differential scanning calorimetry (DSC), dynamical mechanic analysis (DMA), a test of modulus and tensile strength (with an Instron tensile tester), a water absorption test, and scanning electron microscopy (SEM). The blends showed two composition‐dependent glass transition temperatures. Furthermore, as the SPI content increased, the melting temperature of PEEAMA remained constant but the heat of fusion decreased. These results indicate that SPI and PEEAMA were partially miscible. Morphology observations support these results. Increasing the PEEAMA content resulted in decreases in the modulus and tensile strengths and increases in the elongation and toughness of the blends. Water absorption of the blends also decreased with increased PEEAMA content. Incorporating MDI further decreased the water absorption of the blends. The mechanism of water sorption of SPI was relaxation controlled, and that of the blends was diffusion controlled. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 407–413, 2003     

Rheological and morphological properties of high‐density polyethylene and poly(ethylene–octene) blends

The rheological and morphological properties of blends based on high‐density polyethylene (HDPE) and a commercial ethylene–octene copolymer (EOC) produced by metallocene technology were investigated. The rheological properties were evaluated in steady and dynamic shear experiments at 190°C in shear rates ranging from 90 s^?1 to 1500 s^?1 and frequency range between 10^?1 rad/s and 10² rad/s, respectively. These blends presented a high level of homogeneity in the molten state and rheological behavior was generally intermediate to those of the pure components. Scanning electron microscopy (SEM) showed that the blends exhibit dispersed morphologies with EOC domains distributed homogeneously and with particle size inferior to 2 μm. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2240–2246, 2002