Rheometric Mechanical Spectrometry Research Articles

Clarifying the effects of comonomer distribution between short and long chains on physical and mechanical properties of ethylenic copolymers

AbstractIn this paper, two Zigler‐Natta catalysts (ZNCs) were used to synthesize a commercially available linear low‐density polyethylene (LLDPE), widely used in the packaging industry, on an industrial scale. The catalysts differ only in their ability to distribute comonomers between short and long chains. Both catalysts were fully characterized in the first section, and two similar ethylene/1‐butene copolymers were made using them. Afterward, the produced copolymers were fully characterized using different techniques; namely, differential scanning calorimetry (DSC), successive self‐nucleation and annealing (SSA), oxygen induction time (OIT), melt flow index (MFI), rheometric mechanical spectroscopy (RMS), and a wide range of mechanical experiments. It was revealed that while the presence of comonomers in short chains can reduce their resistance against oxidation (by more than 30%) and can cause a dramatic change in friction coefficients (by more than 20%), some of the other main mechanical properties of the made copolymers were independent of comonomer distribution between long and short chains. In addition, it was shown that ethylenic copolymers' strain hardening modulus (SHM) takes advantage of the homogenous distribution.

Experimental study on the effect of molecular weight and chemical composition distribution on the mechanical response of high‐density polyethylene

AbstractThis article aims to appraise the effect of microstructure comprising molecular weight distribution and chemical composition distribution on the mechanical properties of high‐density polyethylene (HDPE). HDPE resins were synthesized using several titanium–magnesium‐supported Ziegler–Natta catalysts in the industrial gas phase reactor under the same polymerization condition. Gel permeation chromatography and crystallization elution fractionation (CEF) were conducted on the resins to characterize the molecular weight and comonomer distribution. Crystallization, thermal and rheological behavior were evaluated following differential scanning calorimetry, polarization light microscopy, and rheometric mechanical spectrometry. The resins with higher soluble fraction in trichlorobenzene below 80°C (highly branched low molecular weight chains) exhibited longer crystallization time based on the crystallization kinetic obtained from the Avrami model. Rheological determination of the molecular weight between entanglements (Me) and the average lamella thickness based on the Gibbs–Thomson equation revealed that the entanglement density and impact strength decreased, and the average lamella thickness increased with an increase in the ratio of CEF eluted fraction below 80°C to the crystallizable fraction in the range of 80–90°C.

Synthesis of methyltriethoxysilane-modified calcium zinc phosphate nanopigments toward epoxy nanocomposite coatings: Exploring rheological, mechanical, and anti-corrosion properties

In this study, the effects of unmodified calcium zinc phosphate (UCZP) and modified calcium zinc phosphate (MCZP) nanopigments (NPs) on the rheological, mechanical, and corrosion protection performance (CPP) of the epoxy (EP) coatings were investigated. Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to study morphology and overall chemical structure of synthesized calcium zinc phosphate (CZP) NPs, respectively. The grafting of methyltriethoxysilane (MTES) molecules on the surface of CZP was assessed using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and contact angle (CA) measurements. The rheological-mechanical properties and anti-corrosion ability of the prepared coatings were assessed by rheometric mechanical spectroscopy (RMS), tensile test, micro-Vickers hardness (MVH) measurements, salt spray, electrochemical impedance spectroscopy (EIS) and pull-off tests. A 1.3° increase in CA was seen for MCZP NPs after silanization. The total resistance (Rt = coating resistance (Rc) + charge transfer resistance (Rct)) of EP coating increased from 0.4 MΩ cm2 to 50.1 and 25,118.8 MΩ cm2 in the presence of UCZP and MCZP NPs, respectively, after 50 days of immersion in 3.5 wt% NaCl solution. A 32.6 % and 24.6 % reduction in the adhesion loss were observed for the UCZP and MCZP NPs filled EP coatings, respectively.

Thermal Diffusivity and Conductivity of Polyolefins by Thermal Lens Technique.

A mode-mismatched thermal lens spectrometry (TLS) technique, in a pump–probe two-laser-beam configuration, was employed for the experimental determination of the thermal properties of four selected well-characterized polyolefin homopolymer films. We investigated the thermal diffusivity (D) and thermal conductivity (κ) of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene. We also measured the structural properties (i.e., average molecular weight, polydispersity index, branching number), along with the rheological and thermal properties (i.e., melting point, specific heat capacity Cp, degree of crystallinity) of samples by high-temperature gel permeation chromatography (HT-GPC), rheometric mechanical spectrometry (RMS), differential scanning calorimetry (DSC), and densitometry. The relationship between microstructural properties such as degree of crystallinity, D, and κ was investigated. The results show that there is good correlation between the degree of crystallinity and D. The TL technique enables measurement of D in semitransparent thin films within an uncertainty of 4%.

Parallel reactions in polymerization of ethylene/methyl methacrylate by late-transition-metal catalysts (α-diimine nickel)

Polymerization of ethylene (E)/methyl methacrylate (MMA) was carried out by late-transition-metal catalyst and co-catalysts such as methylaluminoxane (MAO), ethylaluminum sesquichloride (Al2Cl3Et3), and modified methylaluminoxane (MMAO). Moreover, for precise study and profound understanding of the reactions, polymerization of MMA was performed with co-catalysts in the absence of ethylene and catalyst. The samples were analyzed using differential scanning calorimetry (DSC) to determine glass transition temperature (Tg) and melting temperature (Tm). Molecular weights (Mw) were determined by methods of gel permission chromatography (GPC) and rheometric mechanical spectroscopy (RMS). 13C NMR was applied for recognition of molecular structure, the number of branches, and tacticity. At first, the formation of E/MMA copolymer was expected but in the resulting polymer, two homopolymers of polyethylene and polymethyl methacrylate were obtained instead of E/MMA copolymer. After analyzing the results, it was found that two separate reactions govern the polymerization system, one coordination catalytic polymerization of ethylene, and the second Lewis acid cationic polymerization of MMA. Also, highly branched PE (315 branches per 1000 carbon atoms) with the highest Mw (180,500 g/mol) was obtained at 30 oC, 1 bar ethylene pressure, and 15 mL MMA. The highly syndiotactic PMMA was achieved by co-catalyst of MAO and Al2Cl3Et3 with Tg about 130 oC whereas PMMA generated from MMAO has Tg about 110 oC or less than 110 oC.

In situ polymerization of ethylene in the presence of graphene by α‐diimine Nickel (II)/MAO catalyst system: Thermal and rheological study

In situ polymerization of ethylene with pretreated graphene nano‐platelet (GNP) was carried out by (α‐diimine nickel)/MAO catalyst system. The molecular weight of the synthesized samples was determined using rheometric mechanical spectroscopy. The number of branches and melting temperature values was evaluated by regular differential scanning calorimetry (DSC) and successive self‐nucleation and annealing (SSA) technique. According to obtained results, the molecular weight of the samples was increased from 72,730 to 260,100 g/mol for neat PE and high‐filled GNP, respectively. The number of chain branches decreased by the addition of GNP from 61.51 per 1,000 carbon atoms to 37.10 for neat PE and the sample containing 22.36 wt% of GNP. Obtained results revealed that the samples containing low branches and high molecular weight were achieved in the presence of highly loaded GNP. Also, the electrical conductivity, storage modulus, loss modulus, and complex viscosity of the samples improved by increasing GNP weight fraction.

Zinc-doped silica/polyaniline core/shell nanoparticles towards corrosion protection epoxy nanocomposite coatings

Commercial paints and coatings can serve as a protective barrier for metallic substrates in a corrosive environment. A considerable variety of nanostructures can be embedded in a polymeric coating to achieve both barrier and active protection. This research aims to elucidate the role of polyaniline (PANI) as an active polyelectrolyte modifier for the surface modification of mesoporous silica nanoparticles (MSNs) doped with zinc cations (Zn2+). To characterize the samples, we employed different techniques, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), inductively coupled plasma optical emission spectroscopy (ICP-OES), rheometric mechanical spectroscopy (RMS), differential scanning calorimetry (DSC), tensile, and electrochemical impedance spectroscopy (EIS). Characterization of PANI-MSNs proved the formation of PANI shells onto the surface of silica cores, and pH triggered the release of Zn2+ at the alkaline condition. Enhancement in rheological, thermal, and mechanical characteristics revealed good dispersion and chemical interaction between PANI coated nanoparticles and the epoxy matrix. Moreover, epoxy nanocomposite coatings illustrated a dual barrier/active protection after 50 days of salt immersion.

Application of sustainable saffron purple petals as an eco-friendly green additive for drilling fluids: A rheological, filtration, morphological, and corrosion inhibition study

In this study, effects of dried saffron purple petals (SPP) powder were examined on the rheological, fluid loss, and corrosion inhibition properties of bentonite-based drilling fluids. Drilling fluids containing different amounts of the SPP powder were prepared and their rheological behavior was investigated via the rotary viscometry and rheometric mechanical spectroscopy (RMS). Rotary viscometer results were fitted with Power-law, Bingham plastic, and Herschel-Bulkley models and the obtained data were compared with that of the base mud. All models fitted the rotary viscometer data with the determination coefficients higher than 0.93. The presence of 3 wt% of the SSP in the fluid significantly improved the fluid’s yield stress and consistency index by 223.3% and 94.4%, respectively compared to those of the base mud. The filtration performance and cake formation results confirmed a 45% enhancement in the permeation barrier behavior of the fluid containing 3 wt% SPP powder. Electrochemical impedance measurements illustrated that the total impedance of the mild steel increase from 299 to 39,800 Ω cm2 in the presence of 3 wt% SPP powder compared to the control sample. Additionally, potentiodynamic polarization plots indicated a mixed-type inhibition mechanism for the SPP powder with the corrosion rate of 0.004 mm year−1 and inhibition efficiency of 96.5% in the presence of 3 wt% SPP powder. The morphology of mild steel plates immersed in SPP filled fluids demonstrated the formation of corrosion inhibitive layers on the metallic surface, which hindered the anodic and cathodic reactions while a considerable amount of rusts and corrosion products formed for the plate immersed in the base mud. Furthermore, having SPP as an organic green additive would leave no damaging effects on the surrounding environment and ecosystem.

In situ emulsion polymerization and characterization of PVAc nanocomposites including colloidal silica nanoparticles for wood specimens bonding

ABSTRACTPolyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one‐step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of Tg (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48570.

Mechanical, rheological and oxygen barrier properties of ethylene vinyl acetate/diamond nanocomposites for packaging applications

In this work, the effects of the surface-modified nanodiamond particles (NDs) on the barrier, rheological, mechanical and thermal properties of ethylene vinyl acetate (EVA) composites for the packaging applications were investigated. Fourier transform infrared spectroscopy, as well as thermal gravimetric analysis were employed to study the grafting of vinyltriethoxy silane (VTS) on the surface of NDs. Afterwards, EVA samples containing 0, 0.1, 0.5, 1, 1.5 and 2 wt% of surface-modified NDs were prepared by a two-stage process including the solution and injection processes. In order to evaluate the physicochemical, rheological, mechanical and thermal properties of the EVA/NDs samples, field emission scanning electron microscopy, contact angel measurement, rheometric mechanical spectroscopy, tensile test, differential scanning calorimetry, and thermogravimetric analysis were employed. The result showed a more uniform dispersion of modified NDs in the EVA matrix. Also, the oxygen permeability rate of EVA films in the presence of NDs was reduced remarkably. Furthermore, the mechanical characteristic and thermal stability of the EVA matrix were enhanced significantly in the presence of the modified NDs and the EVA/NDs nanocomposite films have this capability to use for the packaging applications.

Applications of highly salt and highly temperature resistance terpolymer of acrylamide/styrene/maleic anhydride monomers as a rheological modifier: Rheological and corrosion protection properties studies

Due to the weak performance of commercially affordable natural and synthetic polymeric thickeners in high temperatures and salinity, they fail to use in many applications especially in saline conditions with high temperatures. In this work, a new salt and temperature resistance acrylamide/styrene/maleic anhydride terpolymer (PASM-t) with self-associative properties was synthesized via a one-step inverse emulsion polymerization and its applicability as a rheological modifier and thickener was investigated. The characteristics of synthesized PASM-t (s-PASM-t) and its aqueous solutions were investigated using FT-IR, FE-SEM, GPC and rheometric mechanical spectrometry (RMS) analyses. The rheological investigations revealed that the shear viscosity of aqueous increases with the increment of temperature (from 30 °C to 80 °C) and salt concentration (from 5000 to ‌50000 ppm). High-temperature aging test at 150 °C for 12 h of terpolymer aqueous solutions was revealed the unique dramatical increment of rheological properties promoted in the presence of the salt. Rheological behavior and corrosion protection properties of bentonite-based drilling fluid containing s-PASM-t were investigated and results were compared with those of the neat mud and the mud containing commercial carboxymethyl cellulose (CMC). Presented results showed that the s-PASM-t modified mud and shows the better rheological and corrosion resistance performance.

Preparation and characterization of PVDF/Starch nanocomposite nanofibers using electrospinning method

In this study, poly (vinylidene fluoride) PVDF/Starch nanofibers with a great potential for tissue engineering applications have been investigated. The electrospun nanofibers were formed by the electrospinning of the PVDF/Starch solutions in various ratios of PVDF to Starch. Characterizations of PVDF/Starch nanofiber were performed using rheometric mechanical spectroscopy (RMS), field emission scanning electron microscope (FE-SEM) and tensile test. The results showed that the addition of more Starch into the PVDF solution increased the viscosity of the prepared PVDF/Starch solutions. In addition, the mechanical properties of PVDF enhanced in the presence of Starch due to the higher mechanical properties of Starch chains. Also, addition of Starch into PVDF matrix increased the elongation at break from 58 to 8 mm.

A morphological study on the migration and selective localization of graphene in the PLA/PMMA blends

ABSTRACTNano‐filled polymer blends offer the opportunity to obtain materials with fine‐tuned properties. In this work, the dispersion and localization behavior of graphene nanoplate (GNP) and graphene oxide (GO) in solution mixed blends of polylactic acid (PLA) and polymethyl methacrylate (PMMA) were investigated. The blends were prepared by using different mixing sequences to investigate the effect of kinetics parameters and surface chemistry of filler as well as thermodynamics affinity on the localization of fillers. Field Emission Scanning Electron Microscopy (FESEM) and Rheometric Mechanical Spectroscopy (RMS) were employed. In addition, graphene materials were compared by Fourier transform infrared and Raman spectroscopy as well as elemental analysis characterization. Results showed that depending on the mixing sequence, the GNPs were localized in the both phases and interface through migration to reach thermodynamics equilibrium. However, GO localization was significantly affected by the mixing sequence due to better interaction with the polymer phases. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43799.

Preparation and characterization of poly(ethylene terephthalate)/hyperbranched polymer nanocomposites by melt blending

In this paper, nanocomposites of polyethylene terephthalate (PET) including polyesteramide-based hyperbranched polymer, or PET/Hyperbranched polymer nanocomposites, have been prepared via melt blending method with different hyperbranched polymer contents. In addition, morphology, surface structure, and thermal properties of these nanocomposites and virgin PET were studied by atomic force microscopy, attenuated total reflection fourier transform infrared spectroscopy and differential scanning calorimetry (DSC), respectively. Dynamic mechanical analysis experiments in solid state were carried out to follow the effect of hyperbranched polymer on the dynamic mechanical properties of these nanocomposites. The structure of the nanostructured hyperbranched polymer was also studied by small-angle X-ray scattering. The rheometric mechanical spectroscopy results showed that the hyperbranched polymer as a modifier decreased the complex viscosity and enhanced liquid-like behavior. This happened more significantly by increasing the content of hyperbranched polymer. The DSC analysis results revealed that crystallinity and glass transition temperature decreased by adding the amount of hyperbranched polymer.

Dynamic mechanical behavior and nanostructure morphology of hyperbranched‐modified polypropylene blends

AbstractPolypropylene (PP) was modified utilizing two types of polyesteramide‐based hyperbranched polymers (amphiphilic PS and hydrophilic PH). A maleicanhydride‐modified PP (PM) was used as a reactive dispersing agent to enhance the modification by grafting the hyperbranched polymers onto the PP chains. Pure PP, two different non‐reactively modified samples, i.e. excluding PM, and two different reactively modified samples, i.e. including PM, were studied. Investigating the morphology of the samples was performed by scanning electron microscopy. To follow the effect of the modification on the dynamic mechanical properties, dynamic mechanical analysis experiments both in the melt (rheometric mechanical spectrometry) and in solid state (dynamic mechanical thermal analysis) were carried out. In the next step, the nanocrystalline structure of the samples was studied by small angle X‐ray scattering (SAXS) in two different modes, i.e. static and recrystallization. Hundreds of SAXS patterns were analyzed automatically using procedures written in PV‐WAVE image‐processing software. The chord distribution function (CDF) was calculated and the long period (lp) of the crystal lamellae was extracted from the CDFs. The rheometric mechanical spectrometry results show that both hyperbranched polymers decrease complex viscosity η* and enhance liquid‐like behavior. This happens more significantly when PM is included. The dynamic mechanical thermal analysis results reveal that Tg decreases when PS and PH are added. In the reactively modified samples this reduction is compensated most probably because of the crosslinked structure formed through the grafting reaction between the hyperbranched polymers and PM. Such structure is confirmed by SAXS data and calculated CDFs in the recrystallization mode. Static SAXS data also show enhancement in the crosshatched morphology of the crystalline lamellae of PP for reactively modified samples compared with non‐reactively modified samples. © 2013 Society of Chemical Industry

Rheological and thermal properties of glycidyl azide polyol‐based energetic thermoplastic polyurethane elastomers

AbstractThe purpose of this study was to investigate the effects of polyol on glycidyl azide polyol (GAP)‐based energetic thermoplastic polyurethane elastomers (ETPEs). Briefly, a series of GAP/polyol‐based ETPEs (GAP/polyol ETPEs) with different copolyol ratios and hard segment contents were synthesized using GAP‐diol with common polyol and 4,4‐methylenebis(phenylisocyanate)‐extended 1,5‐pentanediol as soft and hard segments, respectively, by solution polymerization in dimethylformamide. The three types of polyols used were poly(tetramethylene ether) glycol (PTMG), polycarbonate‐diol (PCL‐diol) and polycaprolactone‐diol (PCD‐diol). The synthesized GAP/polyol ETPEs were identified and characterized using Fourier transform infrared and 1H NMR spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and rheometric mechanical spectrometry. For GAP/PCL ETPEs with lower hard segment content, DSC results showed that the GAP segment failed to interact with either the PCL segment or PCL melting. In addition, the results of DMA showed that the presence of PCL segments in ETPEs improved the storage modulus below the melting temperature of the PCL block. Further, the crystalline PCL segments were attributed to reinforcing the ETPEs in a manner similar to that of the hard domain. As the hard segment content increased in the GAP/polyol ETPEs, both GAP/PTMG ETPEs and GAP/PCL ETPEs exhibited microphase separation transitions, while rheological experiments demonstrated a sudden decrease in complex viscosity in neighboring microphase separation transitions. © 2012 Society of Chemical Industry

Parameters affecting the free‐radical melt grafting of maleic anhydride onto linear low‐density polyethylene in an internal mixer

AbstractOur main objective of this study was to study the parameters affecting the free‐radical melt grafting of maleic anhydride (MA) onto linear low‐density polyethylene (LLDPE) with dicumyl peroxide (DCP) in an internal mixer. The degree of grafting (DG) was measured with titrometry and Fourier transform infrared spectroscopy. The extent of chain‐branching/crosslinking was evaluated with gel content and melt flow index measurements. The flow behavior and melt viscoelastic properties of the grafted samples were measured by using rheometric mechanical spectrometry. Feeding order, DCP and MA concentration, reaction temperature, rotor speed, and grade of LLDPE were among parameters studied. The results show that the reactant concentration (MA and DCP) played a major role in the determination of the grafting yield and the extent of the chain‐branching/crosslinking as competitive side reactions. The order of feeding also had an appreciable effect on the DG and the side reactions. Increasing the rotor speed increased the grafting yield and reduced side reactions by means of intensification of the mixing of reactants into the polyethylene (PE) melt. Chain‐branching dominated the side reactions for lower molecular weight PE, whereas for higher molecular weight PE, chain‐branching led to crosslinking and gel formation. The results of the melt viscoelastic measurements on the grafted samples provided great insight into the understanding of the role of influential parameters on the extent of side reactions and resulting changes in the molecular structure of the grafted samples. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 141–149, 2006

Relationship between the rheology and morphology of dynamically vulcanized thermoplastic elastomers based on EPDM/PP

AbstractRelationship between the rheological properties and morphology of dynamically vulcanized thermoplastic elastomers (TPVs) based on Ethylene Propylene Diene Monomer (EPDM) and Polypropylene (PP) blends containing 20, 40 and 60% of EPDM were studied. The samples were prepared in a laboratory internal mixer at a rotor speed of 60 rpm. We performed morphological studies on the cryogenically fractured samples using scanning electron microscopy (SEM). The rheological behavior and melt viscoelastic properties of the samples were studied by rheometric mechanical spectrometry (RMS) at a temperature of 220°C. The TPV samples showed a significant viscosity upturn and a strong storage modulus that tended to plateau at low shear rates, with the highest extent for the sample containing 60% of EPDM. These results were attributed to a network structure resulting from agglomerates formed between the cured rubber particles, as evidenced by the morphological features of the samples. The multiple elastic response, expressed in terms of relaxation time distribution, H(λ), exhibited by the molten TPV sample containing 60% of EPDM suggests that apart from the contribution of flow‐induced molecular orientation of the PP matrix, there may also exist some elastic response induced by agglomerates formed between the cured rubber particles. The results predicted from the linear viscoelastic model proposed in the present work were found to be in good agreement with the experimental results. POLYM. ENG. SCI. 45:84–94, 2005. © 2004 Society of Plastics Engineers.

Viscoelastic behavior of polybutadienes with high 1,4-microstructure and narrow molecular weight distribution

Polybutadienes (PBs) of narrow molecular weight distributions with high 1,4-microstructure were synthesized by sec-butyllithium-initiated, living polymerization. The shoulder-like anomalous behavior of the storage modulus G′(ω) in the terminal zone for PBs was studied using size exclusion chromatography (SEC) and rheometric mechanical spectrometry (RMS). It was found that a high-molecular-weight fraction in the PBs was the main reason for the occurrence of the shoulders. The linear viscoelastic spectra were successfully obtained by the Pade–Laplace method from experimental dynamic data, using either the dynamic storage, G′(ω), or loss, G"(ω), modulus. Both the dynamic moduli and stress relaxation in the linear regime were then calculated with reasonable precision. The feasibility of time–temperature–molecular weight superposition for PBs using this method was demonstrated. The dependencies of relaxation spectra on temperature and molecular weight were obtained by a fitting procedure. Thus, with a known reference state, the relaxation spectrum for a given molecular weight PB at a given temperature can be predicted. The predicted dynamic moduli are in good agreement with experimental data. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1315–1324, 1999

Miscibility and processibility in linear low density polyethylene and ethylene-propylene-butene-1 terpolymer binary blends

Blends of linear low density polyethylene (ethylene-octene-1 copolymer) and ethylene-propylene-butene-1 terpolymer (ter-PP) mixed in a twin-screw extruder have been characterized by using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis, scanning electron microscopy (SEM), rheometric mechanical spectrometry, a capillary rheometer, and a universal test machine. Melting and crystallization behaviors by DSC and the α, β, and γ dynamic mechanical relaxations proposed that the blend is immiscible in the amorphous and crystalline phases by observing the characteristic peaks arised solely from those of the constituents. The lack of interfacial interaction between the components was suggested by the SEM study. A strong negative deviation of melt viscosity from the additive rule and the Cole-Cole plot confirmed the immiscibility in melt state. Incorporation of ter-PP induced a reduction in melt viscosity, shear stress, and final load. Flexural modulus and yield stress were linearly increased with ter-PP content, while the tensile strength and elongation at break were more or less changed. Although this blend system is immiscible in the solid and melt states, addition of less than 20 wt % ter-PP in the blend is viable for engineering applications with the advantages of improved processibility and mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1265–1274, 1997