Effects of the Competition between Grafting Reaction and Decomposition on the Miscibility and Rheological Behaviors of PS/POE Blends in the Presence of AlCl3

For increasing the compatibility of polystyrene (PS) and polyolefin elastomer (POE) blends, a Lewis acid catalyst, aluminium chloride (AlCl₃), was adopted to initiate the Friedel-Crafts alkylation reaction and induce the formation of PS-graft-POE copolymer. The dynamic mechanical and rheological tests were used to study the effects of catalyst content on the miscibility and rheological behaviors. The results showed that the viscosity increased and the MFI decreased with the increase of the catalyst content. However, when the catalyst content was overmuch, the viscosity decreased and the MFI increased. The variety of miscibility and rheological behaviors of PS/POE blends was the results of the competition between in situ graft reaction and decomposition of blending compounds.     

In situ compatibilization of polystyrene/polyolefin elastomer blends by the Friedel–Crafts alkylation reaction

Blends of polystyrene (PS) with polyolefin elastomer (POE) were prepared by a reactive extrusion method. In order to increase the compatibility of the two blending components, a Lewis acid catalyst, aluminium chloride (AlCl₃), was adopted to initiate the Friedel–Crafts alkylation reaction. Fourier‐transform infrared (FTIR) spectra of the PS/POE/AlCl₃ blends extracted with butanone verified the graft structure between the PS and POE. Because the in situ generated PS‐graft‐POE copolymers acted as compatibilizers, the mechanical properties of PS/POE blends were greatly improved. For example, after compatibilization, the Charpy impact strength of an 80/20 (wt%) PS/POE blend was increased from 6.29 to 8.50 kJ m^?2. Scanning electron microscopy (SEM) showed that the size of the droplets decreased from 9–10 µm to less than 2 µm with the addition of AlCl₃. Gel permeation chromatography (GPC) showed competition between the grafting reaction and the degradation of blending components in the presence of AlCl₃. Copyright © 2005 Society of Chemical Industry     

Rheology,morphology, and mechanical properties of reactive compatibilized polypropylene/polystyrene blends via Friedel–Crafts alkylation reaction in the presence of clay

Attempts were made to study the effect of reactive compatibilization via Friedel–Crafts alkylation reaction, using AlCl₃ as a catalyst, on rheology, morphology, and mechanical properties of polypropylene/polystyrene ( PP/PS) blends in the presence of an organoclay (Cloisite 15A). During the reactive compatibilization process, PS showed much more degradation than that of PP in the presence of AlCl₃. It was found that the effect of generation of PP‐g‐PS copolymer at the interface of the PP/PS blend dominates the effects of degradation of PS and PP phases, which manifested itself by increased toughness as well as uniform dispersion of the dispersed PS particles in the PP matrix. Generation of PP‐g‐PS copolymer was confirmed by using Fourier‐transform infrared analysis. By using rheological and X‐ray diffraction analyses, it was shown that the clay had higher affinity to PS than that of PP. It was also shown that the clay located at the interface of PP and PS phases, leading to increased relaxation time of the deformed PS dispersed particles, exhibited higher dispersion in PP/PS blend, which resulted in higher ductility of the blend. By using the results of rheological studies, it was concluded that during reactive compatibilization of the blend nanocomposite, the clay migrated into the dispersed PS phase, which was confirmed by scanning electron microscopy analysis. It was demonstrated that the rheological studies have a reliable sensitivity to the clay partitioning and phase morphology of the studied blends and blend nanocomposites . J. VINYL ADDIT. TECHNOL., 24:18–26, 2018. © 2015 Society of Plastics Engineers     

Rheology, morphology and tensile properties of reactive compatibilized polyethylene/polystyrene blends via Friedel–Crafts alkylation reaction

Attempts were made to study the effect of reactive compatibilization via Friedel?CCrafts alkylation reaction, using AlCl₃ as a catalyst, on rheology, morphology, and mechanical properties of polyethylene/polystyrene (PE/PS) blends. The results of linear viscoelastic measurements in conjunction with the results of the mixing torque variation indicated that PS showed much more degradation than that of PE in the presence of AlCl₃. It was also found that while for PE-rich blends, the viscosity, and storage modulus increased by reactive compatibilization, they decreased for PS-rich blends. The variation of viscosity and storage modulus for 50/50 blend was found to be dependent on frequency ranges showing the competitive effects of PE?Cg?CPS copolymer formation and PS degradation. The results of morphological studies showed that reactive compatibilization decreased the particle size and particle-size distribution broadness because of in situ graft copolymer formation. Reactive compatibilization enhanced the tensile strength and elongation at break for PE-rich blends. It was demonstrated that there is a close interrelationship between rheology, morphology, and mechanical properties of reactive compatiblized PE/PS blends. It was also demonstrated that rheological behaviors have a reliable sensitivity to follow the structural and morphological changes during compatibilization process, so that, those information can be used to predict the morphology as well as mechanical properties of the blends.     

Dynamic rheological and morphological study of the compatibility of thermoplastic polyurethane/ethylene–octene copolymer blends

Two grafted ethylene–octene copolymers [POEs; i.e., POE‐g‐maleic anhydried (MAH) and aminated POE (denoted by POE‐g‐NH₂) were used as compatibilizers in immiscible blends of thermoplastic polyurethane (TPU) and POE. The effects of the compatibilizers on the dynamic rheological properties and morphologies of the TPU/POE blends were investigated. The characteristic rheological behaviors of the blends indicated that the strong interactions between the two phases were due to the compatibilization. Microstructural observation confirmed that the compatibilizers were located at the interface in the blends and formed a stable interfacial layer and smaller dispersed phase particle size. Compared with POE‐g‐MAH, POE‐g‐NH₂ exhibited a better compatibilization effect in the TPU/POE blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polyolefin/polystyrene in situ compatibilization using Friedel–Crafts alkylation

Polyolefin/polystyrene (PS) blends are difficult to compatibilize using in situ reactive compatibilization techniques, because neither of these polymers has any functional groups that one can use in the formation of a copolymer from these polymer components. In this study, the Friedel–Crafts alkylation was realized in a polyethylene/PS (PE/PS) melt blend, which resulted in improved compatibility between PE and PS. A number of Lewis acid compounds were tested as catalysts, among which the AlCl₃ was the most efficient. It was found in this study that the presence of a cocatalyst, such as a cationically polymerizable monomer or a halogenated alkane, significantly enhances the formation of PE-g-PS copolymer. The effects of blending parameters, such as temperature and blending time, on the in situ copolymer formation were investigated. The mechanical properties of compatibilized PE/PS blends were improved considerably. Such an in situ compatibilization technique has potential in the recycling of mixed polymer wastes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1385–1393, 1997     

Improvement of mechanical properties for PP/PS blends by in situ compatibilization

The effect of the in situ compatibilization on the mechanical properties of PP/PS blends was investigated. The application of Friedel-Crafts alkylation reaction to the PP/PS-blend compatibilization was assessed. Styrene/AlCl₃ was used as catalyst system. The graft copolymer (PP-g-PS) formed at the interphase showed relatively high emulsifying strength. Scission reactions, occurring in parallel with grafting, were verified for PP and PS at high catalyst concentration, but no crosslinking reactions were detected. Tensile tests were performed on dog-bone specimens of the blends. Both elongation at break and toughness increased with catalyst concentration. At 0.7% AlCl₃, a maximum was reached, which amounted to five times the value of the property for the uncompatibilized blend. At higher catalyst concentrations these properties decreased along with the PP molecular weight due to chain-scission reactions. On the other hand, the tensile strength did not change with the catalyst concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties, but were adversely affected by chain scissions at high catalyst contents.     

In situ compatibilization of polypropylene/polystyrene blend by controlled degradation and reactive extrusion

In situ compatibilization of polypropylene (PP) and polystyrene (PS) was achieved by combinative application of tetraethyl thiuram disulfide (TETD) as degradation inhibitor and di‐tert‐butyl peroxide as degradation initiator in the process of reactive extrusion. The PP/PS blends obtained were systematically investigated by rheological measurement, scanning electron microscopy, and differential scanning calorimetry. The results indicate that peroxide‐induced degradation of PP can be effectively depressed by adding TETD, which may favor the formation of PP‐g‐PS copolymer during melt processing. The PP‐g‐PS copolymer formed may act as an in situ compatibilizer for PP/PS blends, and subsequently decreases the size of dispersed PS phase and changes both rheological and thermal properties of the blends. Based on the present experimental results, the mechanisms for the controlled degradation of PP and in situ formation of PP‐g‐PS copolymer in the PP/PS blends have been proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Localized compatibilization in immiscible blends of thermoplastic polyurethane and ethylene‐octylene copolymer

To prepare thermoplastic polyurethane (TPU)/ethylene‐octylene copolymer (POE) blends, which are thermodynamically immiscible, maleated POE and aminated POE were incorporated as compatibilizers. Effect of addition of the compatibilizers and their contents on morphology, coalescence, and mechanical properties of TPU/POE blends were investigated. The microstructural observation revealed that the compatibilizers are located at the interface in the blends, forming a stable interfacial layer. As a result, the dispersed phase particle size was greatly reduced and tensile properties of the blends were significantly improved. POE‐NH₂ provides the blends with higher compatibility than POE‐MA. The interfacial interaction offered by the compatibilizers was found to be a function of the amount of the reactive groups grafted onto POE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of in situ synthesized macroactivator on morphology of PA6/PS blends via successive polymerization

In situ polymerization and in situ compatibilization was adopted for preparation of ternary PA6/PS‐g‐PA6/PS blends by means of successive polymerization of styrene, with TMI and ε‐caprolactam, via free radical copolymerization and anionic ring‐opening polymerization, respectively. Copolymer poly(St‐g‐TMI), the chain of which bears isocyanate (? NCO), acts as a macroactivator to initiate PA6 chain growth from the PS chain and graft copolymer of PS‐g‐PA6 and pure PA6 form, simultaneously. The effect of the macroactivator poly(St‐g‐TMI) on the phase morphology was investigated in detail, using scanning electron microscopy. In case of blends with higher content of PS‐g‐PA6 copolymer, copolymer nanoparticles coexisting with the PS formed the matrix, in which PA6 microspheres were dispersed evenly as minor phase. The content of the compositions (homopolystyrene, homopolyamide 6, and PS‐g‐PA6) of the blends were determined by selective solvent extraction technique. The mechanical properties of PA6/PS‐g‐PA6/PS blends were better than that of PA6/PS blends. Especially for the blends T10 with lower PS‐g‐PA6 copolymer content, both the flexural strength and flexural modulus showed significantly improving because of the improved interfacial adhesion between PS and PA6. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Compatibility of reactively compatibilized polyamide 11 (nylon 11)/polyethylene (PE) alloys

The compatibility of nylon 11/polyethylene (PE) alloys on addition of reactive maleated ethylene‐propylene‐diene copolymer (EPDM‐graft‐MAH) was investigated by differential scanning calorimetry, morphological observations and rheology. The decrease in the differential volume of the melting temperature of nylon 11 and PE with increasing compatibilizer suggests that the addition of EPDM‐graft‐MAH affects the crystalline behavior of nylon 11 and PE. The decreased particle size of the dispersed phase also confirmed the improvement in the compatibility. The rheological behavior revealed that the addition of the compatibilizer enhanced the apparent viscosity of the melting blends, which resulted from the increasing interaction between the chains due to the improvement in compatibility of nylon 11 and PE. Copyright © 2004 Society of Chemical Industry     

Self‐assembled nanoblends of functional polystyrene and a reactive aramid: Morphological and thermomechanical profile

Various blends composed of pure polystyrene (PS) and modified PS [amino‐functionalized polystyrene (PS–NH₂)] were prepared with a new aromatic polyamide obtained through the polycondensation of 1,5‐diaminonaphthalene and 1,4‐phenylenediamine with isophthaloyl chloride. The variation in the morphological and thermophysical profiles in the two blend systems with aramid loading were investigated. The amine functionality introduced to PS enhanced its compatibility with the polyamide because of the formation of an aramid‐graft‐PS copolymer. The grafting, hydrogen bonding, and phenylene‐ring (π–π) stacking between the chains of the two components finally nurtured self‐assembled nanostructured blends. A strong compatibilizing effect was observed for the 50, 60, and 70 wt % aramid blends, where an exceptionally inimitable cocontinuous self‐assembled morphology was formed by PS–NH₂/aramid. Significant developments in the morphology along with thermal and mechanical stability were observed for the reactive PS/aramid system. The most favorable mechanical and thermal data supported by the finest nanostructure were observed with 70 wt % polyamide addition. Future prospects may involve the formation of nanotemplates and nanostructured membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39954.     

Effect of the compatibilizer on the morphology and properties of dynamically cured PP/POE/epoxy blends

Dynamic vulcanization was successfully applied to epoxy resin reinforced polypropylene (PP)/ethylene‐octene copolymer (POE) blends, and the effects of different compatibilizers on the morphology and properties of dynamically cured PP/POE/epoxy blends were studied. The results show that dynamically cured PP/POE/epoxy blends compatibilized with maleic anhydride‐grafted polypropylene (MAH‐g‐PP) have a three‐phase structure consisting of POE and epoxy particles dispersed in the PP continuous phase, and these blends had improved tensile strength and flexural modulus. While using maleic anhydride‐grafted POE (MAH‐g‐POE) as a compatibilizer, the structure of the core‐shell complex phase and the PP continuous phase showed that epoxy particles could be embedded in MAH‐g‐POE in the blends, and gave rise to an increase in impact strength, while retaining a certain strength and modulus. DSC analysis showed that the epoxy particles in the blends compatibilized with MAH‐g‐PP were more efficient nucleating agents for PP than they were in the blends compatibilized with MAH‐g‐POE. WAXD analysis shows that compatibilization do not disturb the crystalline structure of PP in the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Toughened polyoxymethylene by polyolefin elastomer and glycidyl methacrylate grafted high‐density polyethylene

Ternary blends of polyoxymethylene (POM), polyolefin elastomer (POE), and glycidyl methacrylate grafted high density polyethylene (GMA‐g‐HDPE) with various component ratios were studied for their mechanical and thermal properties. The size of POE dispersed phase increased with increasing the elastomer content due to the observed agglomeration. The notched impact strength demonstrated a parabolic tendency with increasing the elastomer content and reached the peak value of 10.81 kJ/m² when the elastomer addition was 7.5 wt%. The disappearance of epoxy functional groups in the POM/POE/GMA‐g‐HDPE blends indicated that GMA‐g‐HDPE reacted with the terminal hydroxyl groups of POM and formed a new graft copolymer. Higher thermal stability was observed in the modified POM. Both storage modulus and loss modulus decreased from dynamic mechanical analysis tests while the loss factor increased with increasing the elastomer content. GMA‐g‐HDPE showed good compatibility between the POM matrix and the POE dispersed phase due to the reactive compatibilization of the epoxy groups of GMA and the terminal hydroxyl groups of POM. A POM/POE blend without compatibilizer was researched for comparison, it was found that the properties of P‐7.5(POM/POE 92.5 wt%/7.5 wt%) were worse than those of the blend with the GMA‐g‐HDPE compatibilizer. POLYM. ENG. SCI., 57:1119–1126, 2017. © 2017 Society of Plastics Engineers     

Influence of a compatibilizer on the properties of polyethylene–octene elastomer/starch blends

The effect of a compatibilizer on the properties of corn starch‐reinforced metallocene polyethylene–octene elastomer (POE) blends was studied. The compatibility between POE and starch was improved markedly with an acrylic acid‐grafted POE (POE‐g‐AA) copolymer as a compatibilizer. Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy, differential scanning calorimetry, and scanning electron microscopy were used to examine the blends produced. The size of the starch phase increased with an increasing content of starch for noncompatibilized and compatibilized blends. The POE/starch blends compatibilized with the POE‐g‐AA copolymer lowered the size of the starch phase and had a fine dispersion and homogeneity of starch in the POE matrix. This better dispersion was due to the formation of branched and crosslinked macromolecules because the POE‐g‐AA copolymer had anhydride groups to react with the hydroxyls. This was reflected in the mechanical properties of the blends, especially the tensile strength at break. In a comparison with pure POE, the decrease in the tensile strength was slight for compatibilized blends containing up to 40 wt % starch. The POE‐g‐AA copolymer was an effective compatibilizer because only a small amount was required to improve the mechanical properties of POE/starch blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1792–1798, 2002     

Bentonite as a reinforcing and compatibilizing filler for natural rubber and polystyrene blends in latex stage

Bentonite clay was used as a reinforcing and compatibilizing filler for natural rubber/polystyrene (NR/PS) blend via latex blending process. The reinforcing and compatibilizing performance of bentonite clay in the NR/PS blends were evaluated. The improvement of the mechanical properties of NR/PS blends with the weight ratios of 90/10, 80/20, and 70/30 was found with the addition of 3 and 5 parts per hundred rubber (phr) clay. The characterization by using Fourier transform infrared spectroscopy and X‐ray diffraction (XRD) gave the evidence that the silicate layer was intercalated by NR and PS molecular chains. The morphology of tensile fracture surface by scanning electron microscope showed the separated phase boundaries of PS and NR blend and gradual disappearance with the bentonite content. This could be implied that the bentonite contributes to the compatibilization between PS and NR. The compatibilization action of the bentonite clay was also reflected by the shift of glass transition temperature (T_g) of NR to higher temperatures than those of the blends. These results suggested that the tensile and tear properties of the blends were controlled by compatibility between NR and PS. The most enhanced properties of blends were found with the addition of 3 phr bentonite clay. POLYM. ENG. SCI., 54:1436–1443, 2014. © 2013 Society of Plastics Engineers     

Synergistic effects of silica nanoparticles and reactive compatibilizer on the compatibilization of polystyrene/polyamide 6 blends

This study examines the selective dispersion of nano‐SiO₂ in polystyrene (PS) and polyamide 6 (PA6) blends. With the coupling assistance of 3‐methacryloylpropyl trimethoxysilane (MPS), nano‐SiO₂ surfaces are grafted with PS chains of different molecular weights (SiO₂–MPS–PS) or reactive random copolymer of styrene (St) and 3‐isopropenyl‐α,α′‐dimethylbenzene isocyanate (TMI) to produce SiO₂–MPS–P(St–co–TMI). The isocyanate groups of the reactive copolymer can react with the terminal group of the PA6 to form a graft copolymer, which helps in controlling the location of nano‐SiO₂ between the PS and PA6 phases. Field‐emission scanning electron microscopy imaging combined with the rheological method was used to investigate the location and dispersion of nano‐SiO₂, as well as the morphology of the PS/PA6 blends, at low nano‐SiO₂ loading. Compared with pristine SiO₂, the modified SiO₂ with different chain lengths adjusted the PA6 phase with refined size and narrow size distribution because of the strong interaction with both phases. The SiO₂–MPS–PS with appropriate length is the most effective. The use of nano‐SiO₂ along with the reactive compatibilizer provides synergistic effects for improving the compatibilization of PS/PA6 blends. POLYM. ENG. SCI., 57:1301–1310, 2017. © 2017 Society of Plastics Engineers     

Synthesis of polypropylene graft copolymers from a hydroxyl‐groups‐containing polypropylene precursor via atom‐transfer radical polymerization

Isotactic polypropylene graft copolymers, isotactic[polypropylene‐graft‐poly(methyl methacrylate)] (i‐PP‐g‐PMMA) and isotactic[polypropylene‐graft‐polystyrene] (i‐PP‐g‐PS), were prepared by atom‐transfer radical polymerization (ATRP) using a 2‐bromopropionic ester macro‐initiator from functional polypropylene‐containing hydroxyl groups. This kind of functionalized propylene can be obtained by copolymerization of propylene and borane monomer using isospecific MgCl₂‐supported TiCl₄ as catalyst. Both the graft density and the molecular weights of i‐PP‐based graft copolymers were controlled by changing the hydroxyl group contents of functionalized polypropylene and the amount of monomer used in the grafting reaction. The effect of i‐PP‐g‐PS graft copolymer on PP‐PS blends and that of i‐PP‐g‐PMMA graft copolymer on PP‐PMMA blends were studied by scanning electron microscopy. Copyright © 2006 Society of Chemical Industry     

Role of block copolymer on the coarsening of morphology in polymer blend: Effect of micelles

The reactive compatibilization of polystyrene/ethylene‐α‐octene copolymer (PS/POE) blend via Friedel–Crafts alkylation reaction was investigated by rheology and electron microscope. It was found that the graft copolymer formed from interfacial reaction reduced the domain size and decreased the coarsening rate of morphology. The reduction of the interfacial tension is very limited according to the mean field theory even assuming that all block copolymer stays on the interface. With the help of self‐consistent field theory and rheological constitutive models, the distribution of graft copolymer was successfully estimated. It was found that large amount of copolymer had detached from the interfaces and formed micelles in the matrix. Both the block copolymer micelles in matrix and the block copolymers at the interface contribute to the suppression of coarsening in polymer blend, but play their roles at different stages of droplet coalescence. In droplet morphology, the micelles mainly hinder the approaching of droplets. © 2014 American Institute of Chemical Engineers AIChE J, 61: 285–295, 2015     

High impact poly(lactic acid)/poly(ethylene octene) blends prepared by reactive blending

Poly(ethylene octene) grafted with glycidyl methacrylate (POE‐g‐GMA) was prepared and used to toughen poly (lactic acid) (PLA) via reactive blending. It was found that the notched Izod impact strength of PLA/POE‐g‐GMA blends improved dramatically when the content of elastomer was higher than 10 wt%. Reactive compatibilization between PLA and POE‐g‐GMA were studied by Fourier transform infrared spectroscopy (FTIR) and “Molau test,” the results showed the end carboxyl groups of PLA reacted with the epoxide groups of POE‐g‐GMA during blending. This considerably improved the compatibilization, leading to better wetting of the dispersed phase by the PLA matrix and finer dispersed POE‐g‐GMA particles with narrow distribution. Moreover, the critical interparticle distance (L_c) of the dispersed domains for PLA/POE‐g‐GMA blends system at room temperature was also identified. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers