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     

Dynamic mechanical properties of polypropylene‐g‐maleic anhydride and ethylene–propylene–diene terpolymer blends: Effect of blend preparation methods

In this work, we attempted two different ways of processing to improve interfacial adhesion of polypropylene (PP) and ethylene–propylene–diene terpolymer (EPDM) by introducing maleic anhydride (MAH); In one way, the in situ grafting and dynamic vulcanization (ISGV) were performed simultaneously from PP and EPDM with MAH in the presence of dicumyl peroxide (DCP) in an intensive mixer. In another way, PP was first grafted with MAH and then the PP‐g‐MAH was blended with EPDM in the intensive mixer in the presence of DCP by the dynamic vulcanization (DV). It was found that the glass transition temperatures (T_gs) of both PP and EPDM phases were shifted to higher temperature as the EPDM content increased for the blends prepared by both IGSV and DV methods, mainly due to the crosslinking of EPDM. The higher T_gs and larger storage moduli were observed for the blends prepared by the ISGV method than those prepared by the DV method, while the morphology showed that the size reduction of dispersed particles in latter blends was larger than that of the former blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2777–2784, 2000     

Graft copolymerization of oleic acid onto low‐density polyethylene in the molten state

A graft copolymer of oleic acid (OA) onto low‐density polyethylene (LDPE) was prepared using dicumyl peroxide (DCP) as an initiator in the molten state. The grafting was carried out in a Haake rheometer. The effects of the reaction time and the amount of DCP and the monomer on the percentage of grafting were studied. The rheological behavior and the melt‐flow rate of the graft copolymer (LDPE‐g‐OA) were also investigated. FTIR spectroscopy and a mass spectrum were used to characterize the structure of LDPE‐g‐OA. The experimental results showed that when the OA amount was 10 wt % and the DCP amount was 0.4 wt % based on the LDPE the percentage of grafting of LDPE‐g‐OA, prepared by maintaining the temperature at 170°C and the roller speed at 80 rpm, was about 6 wt %. It was found that both LDPE and LDPE‐g‐OA were pseudoplastic fluids. OA was grafted onto LDPE in the form of a monomer and a dimer. The grafted LDPE is expected to act as a compatibilizer between starch and polyethylene. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3299–3304, 2003     

Graft copolymerisation of N‐vinyl pyrrolidone onto polypropylene copolymer in melt: Effect of grafting on thermomechanical properties and paint adhesion

N‐vinyl pyrrolidone (NVP) was grafted onto a polypropylene copolymer (PP) in melt in a Brabender Plasticorder and single screw extruder. The effect of variation of dicumyl peroxide (DCP) and lupersol (LUP) concentrations alone and with 20 wt % NVP concentration in the Brabender Plasticorder on Melt Flow Index (MFI) and final torque values was studied. Variation of NVP concentration (1–10 wt %) at a fixed DCP concentration on percent grafting (G) and MFI was also studied in the single screw extruder. The graft copolymers (PP‐g‐NVP) obtained by reaction of PP with NVP were soxhlet extracted with isopropanol to remove homopolymer, dried, and finally characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PP‐g‐NVP (0–30 wt %) was used as an additive with PP, extruded in the single screw extruder, molded, and the mechanical properties and paint adhesion was measured. MFI values increased and torque values decreased with an increase in initiator concentration, indicating the dominance of the peroxide‐initiated scission reaction over grafting. DCP gave higher grafting compared to LUP. When NVP concentration was increased, MFI values increased initially due to more scission, and then decreased, indicating more graft copolymer formation. Mechanical properties increased by incorporation of PP‐g‐NVP as an additive than PP‐g‐NVP alone. Paint adhesion increased by the presence of PP‐g‐NVP as additive especially with polyurethane primer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2173–2180, 2003     

Synthesis and application of MDPE‐g‐GMA as reactive compatibilizer in blends of MDPE/PET and MDPE/PA6

In the present study, glycidyl methacrylate (GMA) grafted medium density polyethylene (MDPE‐g‐GMA) was synthesized in the molten state and applied as a reactive compatibilizer in MDPE/polyamid6 (PA6) and in MDPE/poly(ethylene terephtalate) (PET) blends. Graft copolymerization of GMA onto MDPE was performed in presence and absence of styrene, with different concentrations of dicumyl peroxide (DCP) as a radical initiator. In the presence of styrene, the MDPE‐g‐GMA with 6% GMA was obtained by addition of only 0.1 phr of DCP. Furthermore, the maximum grafting was reached when 0.6 and 0.7 phr concentration of DCP for styrene containing and styrene free samples were used, respectively. Torque‐time measurement showed faster grafting reaction rate in the presence of styrene. Four MDPE‐g‐GMA samples were selected as compatibilizers in the blends. Furthermore, the effects of melt flow index and grafting content of compatibilizers on mechanical properties and morphology of the blends were investigated through tensile tests and SEM analysis. Tensile test results indicated that the presence of compatibilizers in the blends led to 250 and 133% increase in elongation at break for PA6 and PET blends, respectively. Moreover, the best tensile results for blends were obtained using MDPE‐g‐GMA with high flow ability. The average particle size of the dispersed phase decreased by 350% for PA6 and 300% for PET blends compared with nonreactive blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of compatibilization on the properties of HIPS/PA1010 blends

Blends consisting of high‐impact polystyrene (HIPS) as the matrix and polyamide 1010 (PA1010) as the dispersed phase were prepared by mixing. The grafting copolymers of HIPS and maleic anhydride (MA), the compatibilizer precursors of the blends, were synthesized. The contents of the MA in the grafting copolymers are 4.7 wt % and 1.6 wt %, and were assigned as HAM and LMA, respectively. Different blend morphologies were observed by scanning electron microscopy (SEM); the domain size of the PA1010 dispersed phase in the HIPS matrix of compatibilized blends decreased comparing with that of uncompatibilized blends. For the blend with 25 wt % HIPS‐g‐MA component, the T_c of PA1010 shifts towards lower temperature, from 178 to 83°C. It is found that HIPS‐g‐MA used as the third component has profound effect on the mechanical properties of the resulting blends. This behavior has been attributed to the chemical reaction taking place in situ during the mixing between the two components of PA1010 and HIPS‐g‐MA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 799–806, 2000     

Polypropylene/polypropylene‐grafted acrylic acid copolymer/ethylene–Acrylic acid copolymer ternary blends for hydrophilic polypropylene

Ternary blends of polypropylene (PP), a polypropylene‐grafted acrylic acid copolymer (PP‐g‐AA), and an ethylene–acrylic acid copolymer (EAA) were prepared by melt blending. The surfaces of films with different contents of these three components were characterized with contact‐angle measurements. Scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the microstructure, melting and crystalline behavior, and thermal stability of the blends. The contact angles of the PP/PP‐g‐AA blends decreased monotonically with increasing PP‐g‐AA content. With the incorporation of EAA, the contact angles of the PP/PP‐g‐AA/EAA ternary blends decreased with increasing EAA content. When the concentration of EAA was higher than 15 wt %, the contact angles of the ternary blends began to increase. Scanning electron microscopy observations confirmed that PP‐g‐AA acted as a compatibilizer and improved the compatibility between PP and EAA in the ternary blends. Differential scanning calorimetry analysis suggested that acrylic acid moieties could act as nucleating agents for PP in the polymer blends. Thermogravimetric analysis and differential thermogravimetry confirmed the optimal blend ratio for the PP/PP‐g‐AA/EAA ternary blends was 70/15/15. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 436–442, 2006     

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     

Mechanical property and morphology comparison between the two blends poly(propylene)/ethylene‐propylene‐diene monomer elastomer and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer

The comparison of the mechanical properties between poly(propylene)/ethylene‐propylene‐diene monomer elastomer (PP/EPDM) and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer [PP/MEPDM (MAH‐g‐EPDM)] showed that the latter blend has noticeably higher Izod impact strength but lower Young's modulus than the former one. Phase morphology of the two blends was examined by dynamic mechanical thermal analysis, indicating that the miscibility of PP/MEPDM was inferior to PP/EPDM. The poor miscibility of PP/MEPDM degrades the nucleation effectiveness of the elastomer on PP. The observations of the impact fracture mode of the two blends and the dispersion state of the elastomers, determined by scanning electron microscopy, showed that PP/EPDM fractured in a brittle mode, whereas PP/MEPDM in a ductile one, and that a finer dispersion of MEPDM was found in the blend PP/MEPDM. These observations indicate that the difference in the dispersion state of elastomer between PP/EPDM and PP/MEPDM results in different fracture modes, and thereby affects the toughness of the two blends. The finer dispersion of MEPDM in the blend of PP/MEPDM was attributed to the part cross‐linking of MEPDM resulting from the grafting reaction of EPDM with maleic anhydride (MAH) in the presence of dicumyl peroxide (DCP). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2486–2491, 2002     

Influences of dicumyl peroxide on morphology and mechanical properties of polypropylene/poly(styrene‐b‐butadiene‐b‐styrene) blends via vane‐extruder

Polypropylene (PP) and poly(styrene‐b‐butadiene‐b‐styrene) block copolymer (SBS) were melt‐blended in the presence of initiator system. Dicumyl peroxide (DCP)/Triallyl isocyanurate (TAIC) via self‐deigned VE, aiming at in situ reactive compatibilization of toughed PP/SBS blend. The reactivity, morphology and mechanical properties of PP/SBS/DCP/TAIC blends were studied. Online torque detection was conducted to monitor changes in viscosities of reactive compatibilized blends, which could give proof of the interfacial grafted reaction induced by DCP/TAIC system. The effect of reactive compatibilization on the dispersed particles sizes and interfacial adhesion was studied by scanning electron microscopy. Analysis on mechanical performance revealed the impact strength improved after treated by initiator system, moreover, the impact‐fractured surface observation showed, the failure mode changed from debonding mechanism of neat 50PP/50SBS blend to plastic deformation mechanism of blend containing 3.0 phr initiator system. With improved interfacial adhesion, compatibilized blends not only were toughened but also exhibited enhanced tensile strength and thermal stability. Dynamic mechanical analysis showed a reduction of between PP phase and the PB segments in SBS phase, indicating reactive compatibilization of the blend was achieved. In the final part, a brief discussion was given about the dominant effects from chain scission of PP matrix to intergrafting reactions of PP and SBS, under different content of DCP/TAIC initiator system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41543.     

Synthesis and characterization of dextrin‐grafted polypropylene

We carried out the graft copolymerization of the water‐soluble natural polymer dextrin onto preirradiated polypropylene (PP) in an aqueous medium using benzoyl peroxide (BPO) as the radical initiator. PP was irradiated by γ rays from a Co⁶⁰ source at a constant dose rate of 3.40 kGy/h to introduce hydroperoxide linkages, which served as the sites for grafting. The graft copolymerization was studied as a function of different reaction parameters, and the maximum percentage grafting (P_g; 55%) of dextrin onto PP was obtained at optimum conditions of [BPO] = 5.165 × 10⁻² mol/L, temperature = 60°C in 120 min with 15 mL of water. Different grafting parameters, such as the percentage apparent grafting, percentage grafting, and percentage true grafting have been evaluated. The graft copolymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Swelling studies were carried out in pure, binary, ternary, and quaternary solvent systems composed of water, ethanol (EtOH), dimethyl sulfoxide (DMSO), and N,N‐dimethylformamide (DMF) at different ratios. The maximum swelling percentage PP‐g‐dextrin (both composite and true graft) was observed in pure DMSO and DMF followed by EtOH and water. Water‐retention studies of PP and PP‐g‐dextrin (both composite and true graft) were investigated at different time periods, temperatures, and pH values. The maximum percentage water retention of PP‐g‐dextrin (composite, 124%) was observed at 8 h and 50°C in a neutral medium (pH 7). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymer blends with modified coupling agent. II. Effects of LICA 44 grafted styrene–maleic anhydride copolymer on properties of flame retardant acrylonitrile–butadiene–styrene blends

Flame retardant acrylonitrile–butadiene–styrene (FR‐ABS) blends were prepared by blending tetrabromobisphenol A (TBBA) and antimony trioxide (Sb₂O₃) into the ABS resin. LICA 44 grafted styrene–maleic anhydride (SMA‐g‐L44) copolymers were used as high molecular weight (MW) coupling agents to modify the properties of the FR‐ABS blends, and the copolymers with different LICA 44 grafting ratios were produced via the in vivo and the in situ reactions, respectively. The LICA 44 percentage and the MW of the SMA‐g‐L44 copolymers are important factors influencing the effects of the high MW coupling agent. The impact strength and the tensile yield stress of SMA‐g‐L44 modified FR‐ABS blends increased obviously. The elongation at break and the limiting oxygen index of which also showed an increasing trend after the modification. The coupling effect of SMA‐g‐L44 became weaker at a higher grafting ratio. SEM observation showed that the interfacial boundary in the FR‐ABS became fuzzy after using the SMA‐g‐L44 copolymers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 865–874, 1999     

Peroxide‐catalyzed swell grafting of maleic anhydride onto polypropylene

A new grafting method was developed to incorporate maleic anhydride directly onto solid‐state polypropylene powders. Maleic anhydride grafts altered the nonpolar characteristics of polypropylene so that much better mixing was achieved in blends and composites of polypropylene with many other polymers and fillers. Maleic anhydride was grafted onto polypropylene by the peroxide‐catalyzed swell grafting method, with a maximum extent of grafting of 4.60%. Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, tensile testing, and impact testing were used to characterize the isotactic polypropylene (iPP), maleic anhydride grafted polypropylene (MAH‐g‐iPP), and (isotactic polypropylene)/(calcium carbonate) composites (iPP/CaCO₃). The crystallinity and heat of fusion of the MAH‐g‐iPP decreased as the extent of grafting increased. The mechanical properties of the CaCO₃ filled polypropylene were improved by adding MAH‐g‐iPP as a compatibilizing agent. The dispersion of the fillers in the polymer matrix and the adhesion between the CaCO₃ particles and the polymer matrix were improved by adding the compatibilizer.     

Mechanical characterization of toughened polyamide‐6 blends with metallocene copolymers

The effectiveness as impact modifier of two in situ maleated metallocene copolymers, a metallocene polyethylene, (mPE1) and a metallocene ethylene‐propylene (mEPDM) and three commercial maleated copolymers (mPE2‐g‐MA, EPDM‐g‐MA, and mEPR‐g‐MA) were studied in binary and ternary blends carried out in an intermeshing corotating twin‐screw extruder with polyamide‐6 (PA) as matrix (80 wt %). Also, the effects of the grafting degree, viscosity ratio, and crystallinity of the dispersed phases on the morphological and mechanical properties of the blends were investigated. A significant improvement of the compatibility of these grafted copolymers with PA6 was shown by FTIR spectroscopy, capillary rheometry, and scanning electron microscopy (SEM) in all reactive blends. The tensile strength values of the mEPR‐g‐MA/PA2 binary blend showed the highest strain hardening. The results obtained in this work indicated that the effectiveness of the grafted copolymers as impact modifier depends on the morphology of the blends and a combination of tensile properties of the blend components such as Young's modulus, Poisson ratio, and break stress. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Solvothermal process for grafting dibutylmaleate onto poly(ethylene‐co‐1‐octene)

Solvothermal process was successfully developed to graft dibutylmaleate (DBM) onto poly(ethylene‐co‐1‐octene) (POE) with dicumyl peroxide (DCP) as free radical‐initiator. FTIR spectra demonstrate that DBM is successfully grafted onto the backbone of POE by this novel method. The influences of DBM content, DCP concentration, POE concentration, reaction temperature and reaction time on the grafting copolymerization have been investigated in detail through grafting degree (GD). It is worthy to indicate that high grafting degree (above 15%) can be achieved through the one‐pot way when the graft reaction is carried out in 40 mL toluene at 150°C for 5 h with 1.6 g DBM, 6–8 g POE and 0.35 g DCP. This developed solvothermal process is becoming an effective way to prepare POE‐g‐DBM graft copolymers, and can be extended to other systems. In addition, TGA results show that the thermal properties of POE are enhanced after the grafting reaction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Covulcanization of LLDPE/EMA blends using dicumyl peroxide

The effect of dicumyl peroxide (DCP) content on the gel fraction, mechanical, dynamic mechanical, and thermal properties of linear low‐density polyethylene (LLDPE)/ethylene‐co‐methyl acrylate (EMA) blends were studied. Gel content of the blends increases with increasing DCP content, and EMA is more prone to crosslinking than LLDPE. Wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to study the effect of DCP crosslinking on percent crystallinity and crystalline structure of the blends and individual components. At lower level of DCP loading, crosslinking process does not have significant effect on the crystalline structure of the LLDPE, which was confirmed from the percent crystallinity and lattice distance value. However, at higher DCP content, percent crystallinity decreases significantly. At lower EMA concentration (<50%), percent crystallinity and lattice distance remain unchanged up to 2 wt % of DCP. For EMA contents of more than 50 wt %, increasing DCP content reduces the crystallinity of the blends and increases the lattice distance. The highest level of mechanical and dynamic mechanical properties was observed for 60/40 LLDPE/EMA blends at 2 wt % DCP. Addition of LLDPE‐g‐MA (3 wt %) as a compatibilizer enhances the properties of the vulcanizates. Blends crosslinked with DCP up to 0.3 wt % can easily be reprocessed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel multimonomer‐grafted polypropylene preparation and application in polypropylene/poly(vinyl chloride) blends

A novel grafted polymer was prepared in one step through free‐radical melt grafting in a single‐screw extruder. It was shown that the addition of styrene (St) to the melt‐grafting system as a comonomer could significantly enhance the grafting degree of methyl methacrylate (MMA) onto polypropylene (PP) and reduce the degradation of the PP matrix by means of Fourier transform infrared and melt flow rate testing, respectively. Then, the potential of using multimonomer‐grafted PP, which was designated PP‐g‐(St‐co‐MMA), as the compatibilizer in PP/poly(vinyl chloride) (PVC) blends was also examined. In comparison with PP/PVC blends, the average size of the dispersed phase was greatly reduced in grafted polypropylene (gPP)/PVC blends because of the addition of the PP‐g‐(St‐co‐MMA) graft copolymer. The tensile strength of the gPP/PVC blends increased significantly, and the impact strength was unchanged from that of the pure PP/PVC blends. The results of differential scanning calorimetry and scanning electron microscopy suggested that the compatibility of the PP/PVC blends was improved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Compatibilization of PP/EPDM blends by grafting acrylic acid to polypropylene and epoxidizing the diene in EPDM

In this article, ethylene–propylene–diene‐rubber (EPDM) was epoxidized with an in situ formed performic acid to prepare epoxided EPDM (eEPDM). The eEPDM together with the introduction of PP‐g‐AA was used to compatibilize PP/EPDM blends in a Haake mixer. FTIR results showed that the EPDM had been epoxidized. The reaction between epoxy groups in the eEPDM and carboxylic acid groups in PP‐g‐AA had taken place, and PP‐g‐EPDM copolymers were formed in situ. Torque test results showed that the actual temperature and torque values for the compatibilized blends were higher than that of the uncompatibilized blends. Scanning electron microscopy (SEM) observation showed that the dispersed phase domain size of compatibilized blends and the uncompatibilized blends were 0.5 and 1.5 μm, respectively. The eEPDM together with the introduction of PP‐g‐AA could compatibilize PP/EPDM blends effectively. Notched Izod impact tests showed that the formation of PP‐g‐EPDM copolymer improved the impact strength and yielded a tougher PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3949–3954, 2006     

In situ compatibilization of HDPE/PET blends

The reactive compatibilization of immiscible polymers such as high‐density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) by interfacial grafting of maleic anhydride (MA) without initiator in the molten state was investigated in this study. Grafting reaction of MA onto HDPE was carried out in a Rheocord HAAKE mixer varying reaction parameters such as the temperature, the shear rate, and the time of reaction. Then, the purified copolymers were characterized by infrared spectrometry and the MA content of HDPE‐g‐MA copolymers was determined by volumetric titration. It has been shown that thermomechanical initiation is sufficient to reach grafting yield of 0.3 to 2.5 wt % of MA. We studied then the compatibilization of HDPE/PET blends by interfacial grafting of MA. The in situ interfacial reaction leads to the formation of HDPE‐g‐MA copolymer which acts as a compatibilizer in the blends. The foremost interest of this work is that it provides a simple way of compatibilization of immiscible blends of polyolefin and polyester in one transformation step without using free‐radical initiators. The mechanical properties of the blends are strongly improved by the addition of small quantities of MA. The SEM observations of the compatibilized blends show a deep modification of the structure (i.e., enhanced regularity in the nodule dispersion and better interfacial adhesion). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 874–880, 2001