Structure and properties of in situ compatibilized polystyrene/polyolefin elastomer blends

To increase the compatibility of polystyrene (PS) and polyolefin elastomer (POE) blends, a Lewis acid catalyst, aluminum chloride (AlCl₃), was adopted to initiate the Friedel–Crafts alkylation reaction for the formation of PS‐graft‐POE copolymer. Dynamic mechanical analysis indicated that PS/POE and PS/POE/AlCl₃ blends are partially miscible, and the formation of PS‐graft‐POE copolymer increased the compatibility between PS and POE. Scanning electron microscope and transmission electron microscope results showed that the domain size of the blends decreased dramatically and the size distribution became more uniform with the addition of AlCl₃. Such in situ compatibilization also induced hindrance to the macromolecular chain movement, as reflected by the results of the dynamic rheological analysis. The dynamic rheological behaviors of PS/POE and PS/POE/AlCl₃ blends under different temperature showed that in situ compatibilization weakened the effects of thermooxidation on PS/POE blends. Moreover, in situ compatibilization decreased the activation energy of viscous flow and reduced the influence of temperature on PS/POE blends. POLYM. ENG. SCI., 47:951–959, 2007. © 2007 Society of Plastics Engineers     

Cross‐linking and grafting with PS of EPDM in the presence of Lewis acids

With Lewis Acids as catalysts in melt system, the influence of kinds of Lewis Acids, dosages of catalysts on the behaviors of crosslinking and grafting of ethylene–propylene–diene rubber (EPDM) were investigated. The Lewis Acids, such as anhydrous AlCl₃, FeCl₃, SnCl₄, could initiate the crosslinking of EPDM and the grafting between EPDM and polystyrene (PS). The carbon–carbon double bonds existing on EPDM chain were favorable to the formation of the initial carbocation in the presence of Lewis Acids. The carbocation initiated carbonium ion polymerization between the unsaturated bonds, or substituted for a proton from the phenyl in the presence of PS forming EPDM‐g‐PS copolymer. Anhydrous aluminum chloride was found to be an efficient catalyst and its initiating temperatures for crosslinking or grafting were about 110°C. The amounts of gel and the data of torques showed that there was a competition between the crosslinking‐grafting reaction and the degradation of blending components in the presence of AlCl₃. The EPDM‐g‐PS copolymer served as a compatibilizer in the EPDM/PS blends and enhanced the mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

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     

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     

Influences of ethylene–butylacrylate–glycidyl methacrylate on morphology and mechanical properties of poly(butylene terephthalate)/polyolefin elastomer blends

Elastomer ethylene–butylacrylate–glycidyl methacrylate (PTW) containing epoxy groups were chosen as toughening modifier for poly(butylene terephthalate) (PBT)/polyolefin elastomer (POE) blend. The morphology, thermal, and mechanical properties of the PBT/POE/PTW blend were studied. The infrared spectra of the blends proved that small parts of epoxy groups of PTW reacted with carboxylic acid or hydroxyl groups in PBT during melt blending, resulting in a grafted structure which tended to increase the viscosity and interfere with the crystallization process of the blend. The morphology observed by scanning electron microscopy revealed the dispersed POE particles were well distributed and the interaction between POE and PBT increased in the PBT/POE/PTW blends. Mechanical properties showed the addition of PTW could lead to a remarkable increase about 10‐times in impact strength with a small reduction in tensile strength of PBT/POE blends. Differential scanning calorimetry results showed with increasing PTW, the crystallization temperature (T_c) and crystallinity (X_c) decreased while the melting point (T_m) slightly increased. Dynamic mechanical thermal analysis spectra indicated that the presence of PTW could improve the compatibility of PBT/POE blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40660.     

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     

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     

Crystallization of poly(butylene terephthalate)/poly(ethylene octene) blends: Isothermal crystallization

Poly(ethylene‐octene) (POE), maleic anhydride grafted poly(ethylene‐octene) (mPOE), and a mixture of POE and mPOE were added to poly(butylene terephthalate) (PBT) to prepare PBT/POE, PBT/mPOE, and PBT/mPOE/POE blends by a twin‐screw extruder. Observation by scanning electron microscopy revealed improved compatibility between PBT and POE in the presence of maleic anhydride groups. The melting behavior and isothermal crystallization kinetics of the blends were studied by wide‐angle X‐ray diffraction and differential scanning calorimeter; the kinetics data was delineated by kinetic models. The addition of POE or mPOE did not affect the melting behavior of PBT in samples quenched in water after blending in an extrude. Subsequent DSC scans of isothermally crystallized PBT and PBT blends exhibited two melting endotherms (T_mI and T_mII). T_mI was the fusion of the crystals grown by normal primary crystallization and T_mII was the melting peak of the most perfect crystals after reorganization. The dispersed second phase hindered the crystallization; on the other hand, the well dispersed phases with smaller size enhanced crystallization because of higher nucleation density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheological study of polypropylene copolymer/polyolefinic elastomer blends

Blends of polypropylene copolymer (PP‐cp) and a polyolefinic elastomer (POE) were prepared by a melt‐blending process at 210°C and 60 rpm using a counterrotating twin‐screw extruder. The POE content was varied up to 25%. The shear viscosity over a wide range of shear rate was measured. All blend compositions showed well‐defined zero shear viscosity and shear thinning behavior. The melt viscosity values were between those of the principal components in all cases. Rheology of blends shows different behavior up to concentrations of POE corresponding to the tough–brittle transition. The linear viscoelastic properties (G′, G″, η*, η′, η″) were used to check the miscibility of the two components in the melt state. All blend compositions showed a good degree of miscibility over the range of POE concentrations studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 665–671, 2002; DOI 10.1002/app.10376     

Thermal behavior and properties of polystyrene/poly(methyl methacrylate) blends

The thermal behavior and properties of immiscible blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with and without PS‐b‐PMMA diblock copolymer at different melt blending times were investigated by use of a differential scanning calorimeter. The weight fraction of PS in the blends ranged from 0.1 to 0.9. From the measured glass transition temperature (T_g) and specific heat increment (ΔC_p) at the T_g, the PMMA appeared to dissolve more in the PS phase than did the PS in the PMMA phase. The addition of a PS‐b‐PMMA diblock copolymer in the PS/PMMA blends slightly promoted the solubility of the PMMA in the PS and increased the interfacial adhesion between PS and PMMA phases during processing. The thermogravimetric analysis (TGA) showed that the presence of the PS‐b‐PMMA diblock copolymer in the PS/PMMA blends afforded protection against thermal degradation and improved their thermal stability. Also, it was found that the PS was more stable against thermal degradation than that of the PMMA over the entire heating range. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 609–620, 2004     

Reactive blending of poly (dimethylsiloxane) with nylon 6 and poly (styrene):Effect of reactivity on morphology

Reactive compatibilization was used to control and stabilize 20–30wt% poly(dimethylsioxane) (PDMS) dispersions in nylon 6 (PA) and poly(styrene) (PS), respectively. The effect of the type of reation (amine (NH₂)/anhydride (An), NH₂/ epoxy(E) and carboxylic acid (COOH)/E) on the morphology was studied with electron microscopy. PS and PDMS have mutual solvents thus it was possible to use gel permeation chromatography (GPC) to determine the concentration of block copolymer in PS/PDMS blends. Reactive blending of PA6 with difunctional PDMS‐(AN)₂ did not decrease the PDMS particle size compared to the non‐reactive blend (～10μm). Particle size decreaeased significantly to about 0.5 μm when PA6 was blended with a PDMS containing about 4 random An groups along the chain. For the PS/PDMS blends, GPC revealed that the NH₂/An reaction formed about 3% block copolymer and produced stable PDMS particles ～ 0.4 μm. No reaction was detected for the PS‐NH₂/PDMS‐E blend and the morphology was coarse and unstable. Also, PS‐NH₂/PDMS‐An reactivity was lower compared to other systems such as PS/ poly (isoprene) and PS/poly(methaacrylte) using the same reaction. This was attributed to the relatively thinner PS/PDMS interface dueto the high PS/PDMs immiscibility.     

Study on the properties of polyethylene–octene elastomer/wood flour blends

In the present study, the properties of metallocene polyethylene–octene elastomer (POE) and wood flour (WF) blends were examined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), an Instron mechanical tester, and scanning electron microscopy (SEM). The results showed that the mechanical properties of POE were obviously lowered, due to the poor compatibility between the two phases, when it was blended with WFs. A fine dispersion and homogeneity of WF in the polymer matrix could be obtained when acrylic acid‐grafted POE (POE‐g‐AA) was used to replace POE for manufacture of the blends. This better dispersion is due to the formation of branched and crosslinked macromolecules since the POE‐g‐AA copolymer had carboxyl groups to react with the hydroxyls. This is reflected in the mechanical and thermal properties of the blends. In comparison with a pure POE/WF blend, the increase in tensile strength at break was remarkable for the POE‐g‐AA/WF blend. The POE‐g‐AA/WF blends are more easily processed than are the POE/WF blends, since the former had a lower melt viscosity than that of the latter. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1919–1924, 2003     

Study on toughening effect of maleic anhydride‐grafted‐poly(ethylene‐octene) to EVOH and their compatibility

Blends of poly(ethylene‐co‐vinyl alcohol) (EVOH) with maleic anhydride‐grafted‐poly(ethylene‐octene) (POE‐g‐MAH) were prepared by blending extrusion in order to improve the toughness and flexibility of EVOH. The compatibility behavior of these blends with POE‐g‐MAH content range from 0 to 25 wt% was studied using mechanical, thermal, infrared, and morphology characterization techniques. The mechanical test results showed that POE‐g‐MAH can significantly improve the impact toughness of EVOH with a brittle‐tough transition appeared at the POE‐g‐MAH content of 20 wt%. A huge increase of toughness of the blend was also observed when the POE‐g‐MAH content was increased to 15 wt%. The thermal analysis of the blends demonstrated that the thermal stability of EVOH is improved with the addition of POE‐g‐MAH, adding 20 wt% or more POE‐g‐MAH can effectively decrease the crystallinity of EVOH and greatly improve compatibility between the two components. The existence of esterification between anhydride groups in POE‐g‐MAH and hydroxyl groups in EVOH in melt processing was confirmed using Fourier transform infrared technique. Morphology analysis of the Izod impact fractures has clearly shown the mechanisms for these blends to change from brittle to tough with increasing the POE‐g‐MAH content. POLYM. ENG. SCI., 53:2093–2101, 2013. © 2013 Society of Plastics Engineers     

Deformation mechanism of polystyrene toughened with sub‐micrometer monodisperse rubber particles

Core–shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core‐shell rubber particles were then blended with polystyrene to prepare PS/PB‐g‐PS blends with a constant rubber content of 20 wt%. PB‐g‐PS particles with a lower PB/PS ratio (≤70/30) form a homogeneous dispersion in the polystyrene matrix, and the Izod notched impact strength of these blends is higher than that of commercial high‐impact polystyrene (HIPS). It is generally accepted that polystyrene can only be toughened effectively by 1–3 µm rubber particles through a toughening mechanism of multiple crazings. However, the experimental results show that polystyrene can actually be toughened by monodisperse sub‐micrometer rubber particles. Scanning electron micrographs of the fracture surface and stress‐whitening zone of blends with a PB/PS ratio of 70/30 in PB‐g‐PS copolymer reveal a novel toughening mechanism of modified polystyrene, which may be shear yielding of the matrix, promoted by cavitation. Subsequently, a compression‐induced activation method was explored to compare the PS/PB‐g‐PS blends with commercial HIPS, and the result show that the toughening mechanisms of the two samples are different. Copyright © 2006 Society of Chemical Industry     

Dynamic mechanical properties and morphology of high‐density polyethylene/CaCO3 blends with and without an impact modifier

Dynamic mechanical analysis and differential scanning calorimetry were used to investigate the relaxations and crystallization of high‐density polyethylene (HDPE) reinforced with calcium carbonate (CaCO₃) particles and an elastomer. Five series of blends were designed and manufactured, including one series of binary blends composed of HDPE and amino acid treated CaCO₃ and four series of ternary blends composed of HDPE, treated or untreated CaCO₃, and a polyolefin elastomer [poly(ethylene‐co‐octene) (POE)] grafted with maleic anhydride. The analysis of the tan δ diagrams indicated that the ternary blends exhibited phase separation. The modulus increased significantly with the CaCO₃ content, and the glass‐transition temperature of POE was the leading parameter that controlled the mechanical properties of the ternary blends. The dynamic mechanical properties and crystallization of the blends were controlled by the synergistic effect of CaCO₃ and maleic anhydride grafted POE, which was favored by the core–shell structure of the inclusions. The treatment of the CaCO₃ filler had little influence on the mechanical properties and morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3907–3914, 2007     

Development and characterization of reactively extruded PVC/polystyrene blends

PVC/PS blends are obtained through a reactive extrusion–polymerization method by the absorption of a solution of styrene monomer, initiator, and a crosslinking agent in commercial suspension‐type porous polyvinyl chloride (PVC) particles, forming a dry‐blend with a relatively high monomer content. These PVC/styrene dry‐blends are reactively polymerized in a twin‐screw extruder in the melt state. They do not contain monomer residues as detected by GC. The transparency, fracture surface morphology, thermal stability, rheology and static and dynamic mechanical properties of these blends are compared to physical PVC/PS blends at similar compositions. Owing to the high polymerization temperature (180°C), short PS chains are formed in the reactive extrusion process. These short chains are dispersed both as a separate phase of ～2 μm particles (recognized by SEM) and also as molecularly dispersed chains enhancing plasticization and compatibilization. The molecularly dispersed short PS chains tend to plasticize the PVC phase, reducing its melt viscosity and glass transition temperature. The content of the short PS chains forming the dispersed separate PS particles is too low for DMTA to detect a separate T_g. Thus, reactively extruded PVC/PS blends exhibit single T_g transitions at lower temperatures compared with the neat PVC. Migration of the PVC's low‐molecular‐weight additives (lubricants and thermal stabilizer) to the PS phase is observed in the physical PVC/PS blends, causing antiplasticization of the PS phase. This results in both reduction of the T_g and an increase in the thermal stability of the PS phase in the physical PVC/PS blends. Comparing TGA thermograms of reactively extruded and physical PVC/PS indicates that the PS formed in the extruder is different from the commercial PS. This can stem from various chemical reactions that can take place in the studied reactive polymerization process. Polym. Eng. Sci. 44:1473–1483, 2004. © 2004 Society of Plastics Engineers.     

New generation of thermally stable and conducting poly(azomethine‐ester)s: nano‐blend formation with polyaniline

A new dihydroxy monomer, (E)‐1‐(4‐(4‐(4‐hydroxybenzylidene)thiocarbamoylaminobenzyl)phenyl)‐3‐(4‐hydroxybenzylidene)thiourea, was synthesized and polymerized with thiophene‐2,5‐dicarbonyl/terephthaloyl chloride. The structural characterization of the resulting polymers was carried out using spectral techniques (Fourier transform infrared and ¹H NMR) along with a physical property investigation. Novel polyesters are readily soluble in various amide solvents and possess high molar mass of 112 × 10³–133 × 10³ g mol^?1. The thermal stability was determined via 10% weight loss to be in the range 519–523 °C and the glass transition temperature was 286–289 °C. Electrically conducting poly(azomethine‐ester)‐blend‐polyaniline blends were prepared using mash‐blending and melt‐blending techniques. Materials obtained using the conventional melt‐blending approach generated an efficient conductive network compared with those produced by mash blending. Field emission scanning electron microscopy revealed a nano‐blend morphology for the melt‐blended system owing to increased physical interactions (hydrogen bonding and π–π stacking) between the two constituent polymers. Miscible blends of thiophene‐based poly(azomethine‐ester)‐blend‐polyaniline had superior conductivity (1.6–2.5 S cm^?1) and thermal stability (T₁₀ = 507 °C) even at low polyaniline concentration relative to reported thiophene/azomethine/polyaniline‐based structures. The new thermally stable and conducting nano‐blends could be candidates for various applications including optoelectronic devices. © 2012 Society of Chemical Industry     

Compatibility study in poly(tetramethyleneadipate‐co‐terephthalate)/polystyrene bioblends

Bioblends of the biodegradable copolyester poly(tetramethyleneadipate‐co‐terephthalate) (EBU) and polystyrene (PS) were prepared in different weight compositions on a twin‐screw extruder at 160–200°C. The various bioblend compositions were then investigated using thermogravimetric analysis (TGA), modulated differential scanning calorimetry (MDSC), and Fourier transform infrared photoacoustic spectroscopy (FTIR‐PAS). TGA studies showed that 25/75 and 50/50 EBU/PS blends had higher thermal stability than the more thermally stable blend component, PS. The MDSC studies showed a single T_g and single T_m for the blends, that were concentration independent. The FTIR‐PAS studies indicated a small shift (4–8 cm^?1) in the carbonyl absorption peaks of EBU to lower wavenumbers in 50/50 EBU/PS blend relative to that of neat EBU. It is concluded that, while the MDSC results were inconclusive, the TGA and FTIR‐PAS results support the existence of some degree of intermolecular interaction between EBU and PS components and, hence, partial compatibility in EBU/PS blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology,morphology, and mechanical properties

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003