Performance of multilayer films using maleated linear low-density polyethylene blends

Blends of linear low-density polyethylene (LLDPE) and linear low-density polyethylene grafted maleic anhydride (LLDPE-gMA) were prepared by melt mixing and then coextruded as external layers, with a central layer of polyamide (PA) on three-layer coextruded flat films. Blends with contents of 0% to 55 wt% of maleated LLDPE, on the external layers, were analyzed. The T-peel strength and oxygen and water vapor transmission rate of the films were measured. The surfaces of the peeled films were characterized using attenuated total reflection infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM). The observed increase in T-peel strength of the films with 10% and higher levels of maleated LLDPE in the blend suggests good interfacial adhesion between layers. This sharp increase in peel strength appears to be associated, besides interdiffusion, with specific interactions between polymers, as the bond formation between maleic anhydride and the polyamide end groups by in situ block copolymer formation across the interface. No significant modifications in oxygen barrier properties of the films were observed; however, the use of higher contents of LLDPEgMA, even though it increases the adhesion performance, also increases the water vapor transmission rate by a reduction in the degree of crystallinity.     

Performance of polyethylene/ethylene-vinyl alcohol copolymer/polyethylene multilayer films using maleated polyethylene blends

Blends of linear low density polyethylene (LLDPE) and linear low density polyethylene grafted with maleic anhydride (LLDPE-gMA) were used to promote adhesion between LLDPE and ethylene-vinyl alcohol copolymer (EVOH) in a coextruded three layer flat film, trying to avoid the use of a tie layer. These particular films could be an option when the equipment for a five layer system is not available. The effect of the modified polymer on the surface of cast films was characterized through contact angle measurements. T-peel strength, and oxygen and water vapor transmission rate of the multilayer films were measured as a function of LLDPE-gMA content. Compressed films with 0%, 0.03%, and 0.08% of maleic anhydride (MA) were also analyzed by infrared spectroscopy (FTIR). The increased T-peel strength observed when using MA contents higher than 0.08% suggests a good interfacial adhesion between layers. This increase could be associated with specific interactions between the LLDPE-gMA and the EVOH, as the development of covalent bonds through the reaction of the anhydride with the EVOH hydroxyl groups across the interface. This was proved by the FTIR analysis that showed an increase in the ester band absorbance with an increase on the maleated polymer content and bonding time indicating that a chemical reaction occurred, at the interface. The observed changes on the oxygen and water vapor barrier properties of the films were not significant.     

Morphological study of LLDPE‐NR reactive blending with maleic anhydride

A binary blend and ternary reactive blends of 90/10 LLDPE/NR using maleic anhydride (MA) as a reactive agent with and without dicumyl peroxide (DCP) were made at 150°C in an internal mixer. The fracture surfaces of the blends were conventionally observed by TEM and atomic force microscope, revealing that the rubber domains became smaller with the addition of MA and DCP. This suggested that the in situ graft copolymer (LLDPE‐g‐NR) was formed and acted as an in situ compatibilizer to enhance interfacial adhesion. This was further supported by FTIR results. Importantly, after removal of NR phase from the blends, the remaining LLDPE part was dissolved in hot xylene, purified by precipitation in methanol, and carefully prepared by solvent casting for TEM observation. The microstructures of the solvent‐extracted LLDPE from all blends are unlike that of solvent cast‐ pure LLDPE, which shows only crystalline structure. This leads to an unambiguous way to disclose the existence of an in situ graft copolymer. The solvent‐extracted LLDPE from the blends shows mixed morphology of LLDPE crystalline structure and its in situ graft copolymer as nanofibrillar networks of the NR phase protruded from the amorphous region of the LLDPE matrix due to spinodal decomposition by the solvent removal. Adding MA makes more branches and fibril connections of the NR phase, whereas a thinner fibril network and more links of the NR and the LLDPE amorphous region are found in the reactive blend with MA and DCP, where the most compatibilized blend is obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

A facile route for preparing stable co-continuous morphology of LLDPE/PA6 blends with low PA6 content

A facile method is employed to prepare a series of LLDPE/PA6 blends with co-continuous morphology with low PA6 content via reactive extrusion. In these blends, co-continuous morphology is obtained by introducing graft copolymers with both high and low molecular weight trunk chains to the interface simultaneously. Maleic anhydride functionalized polybutadine (PB-g-MAH, and MAH content = 10 wt%) is first melt grafted onto the LLDPE backbones with dicumyl peroxide (DCP) as an initiator. Part of PB-g-MAH is grafted onto LLDPE to form LLDPE-g-PB-g-MAH copolymer. During reactive extrusion, in-situ formed Copolymer II (polybutadiene-graft-polyamide, PB-g-PA6) with a low molecular weight trunk chain (PB) is obtained from the reaction between the maleic anhydride group of free or non-grafted PB-g-MAH and the amino group on PA6 molecules; while Copolymer I (LLDPE-g-PB-g-PA6) is obtained via the reaction between the maleic anhydride group of the grafted PB-g-MAH (i.e., LLDPE-g-PB-g-MAH) and the amino group of PA6. Copolymer I with a high molecular weight trunk chain, LLDPE, should strengthen the interface and favor stress transfer, enabling the deformation of PA6; and Copolymer II (PB-g-PA6) with a low molecular weight trunk chain, PB, facilitates the formation of a flat interface between LLDPE and PA6, thus promoting an elongated PA6 phase. Therefore, co-continuous morphology of LLDPE/PA6 blend is successfully prepared with only 25 wt% PA6 by controlling suitable amounts of Copolymers I and II in the blend.     

Polyethylene grafted maleic anhydride to improve wettability of liquid on polyethylene films

Blends of linear low density polyethylene (LLDPE) and LLDPE grafted maleic anhydride (LLDPE‐g‐MA) were prepared by melt mixing. The surface of cast films with different contents and types of maleated PE were characterized through contact angle and wetting tension measurements, as well as attenuated total reflection IR spectroscopy. The tensile properties and light transmission of extruded films, as well as the performance of these films compared with commercial “antifog” films, for greenhouses were determined. The carbonyl polar groups on the surface of LLDPE/LLDPE‐g‐MA blends increased, and the equilibrium contact angles of water and dimethylformamide decreased when the content of maleated PE increased. Films made with these blends showed a noticeable reduction in water drop formation as the MA content was increased and when using LLDPE‐g‐MA of lower molecular weight. The light transmission through these films under condensation was improved when using increased contents of MA, which promotes better wetting of the water on the surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1802–1808, 2001     

Study on the microstructures and mechanical behaviour of compatibilized polypropylene/polyamide‐6 blends

A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐g‐MA) or with maleated PP (PP‐g‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by means of tensile and impact testing and by scanning electron microscopy and transmission electron microscopy. The results indicated that the miscibility of PP–PA6 blends was improved with the addition of POE‐g‐MA and PP‐g‐MA. For the PP/PA6/POE‐g‐MA system, an elastic interfacial POE layer was formed around PA6 particles and the dispersed POE phases were also observed in the PP matrix. Its Izod impact strength was four times that of pure PP matrix, whilst the tensile strength and Young's modulus were almost unchanged. The greatest tensile strength was obtained for PP/PA6/PP‐g‐MA blend, but its Izod impact strength was reduced in comparison with the pure PP matrix. © 2002 Society of Chemical Industry     

Synthesis and properties of polyamide/LLDPE composites with compatibilizer used as hot melt adhesive

In this work, a new polyamide (PA155) was synthesized from higher purity dimer acid, sebacic acid, ethylenediamine, and piperazine, and the ternary blends were prepared by blending PA155 with LLDPE in the presence of the compatibilizer, maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MAH). The weight ratio of PA155 to LLDPE of the samples was kept constant at 80/20 and the amount of LLDPE-g-MAH was varied at 0, 3, 6, 9, and 12 wt% over the total weight of the blend respectively. The scanning electron microscope and mechanical properties tests showed that the compatibility and the mechanical properties were improved with the increase in LLDPE-g-MAH content, and the blend containing 9.0 wt% LLDPE-g-MAH exhibits an optimal miscibility behavior and mechanical properties. The hot melt adhesives which were prepared from the ternary blends were assessed by 180°peel tests of Al/adhesive/polypropylene stack. The peeling strength for the sample containing 9.0 wt% compatibilizer (82.5 N/2.5 cm) is much more than that of the samples without compatibilizer (<20 N/2.5 cm).     

Blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 toughened by maleated polystyrene‐based copolymers: Mechanical properties,morphology, and rheology

Poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 (PPO/PA6 30/70) blends were impact modified by addition of three kinds of maleated polystyrene‐based copolymers, i.e., maleated styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA), maleated methyl methacrylate‐butadiene‐styrene copolymer (MBS‐g‐MA), and maleated acrylonitrile‐butadiene‐styrene copolymer (ABS‐g‐MA). The mechanical properties, morphology and rheological behavior of the impact modified PPO/PA6 blends were investigated. The selective location of the maleated copolymers in one phase or at interface accounted for the different toughening effects of the maleated copolymer, which is closely related to their molecular structure and composition. SEBS‐g‐MA was uniformly dispersed in PPO phase and greatly toughened PPO/PA6 blends even at low temperature. MBS‐g‐MA particles were mainly dispersed in the PA6 phase and around the PPO phase, resulting in a significant enhancement of the notched Izod impact strength of PPO/PA6 blends from 45 J/m to 281 J/m at the MBS‐g‐MA content of 20 phr. In comparison, the ABS‐g‐MA was mainly dispersed in PA6 phase without much influencing the original mechanical properties of the PPO/PA6 blend. The different molecule structure and selective location of the maleated copolymers in the blends were reflected by the change of rheological behavior as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Compatibilizer in waste tire powder and low‐density polyethylene blends and the blends modified asphalt

With the increasing ratio of waste tire powder (WTP) to low‐density polyethylene (LDPE), the hardness and tensile strength of the WTP/LDPE blends decreased while the elongation at break increased. Five kinds of compatibilizers, such as maleic anhydride‐grafted polyethylene (PE‐g‐MA), maleic anhydride‐grafted ethylene‐octene copolymer (POE‐g‐MA), maleic anhydride‐grafted linear LDPE, maleic anhydride‐grafted ethylene vinyl‐acetate copolymer, and maleic anhydride‐grafted styrene‐ethylene‐butylene‐styrene, were incorporated to prepare WTP/LDPE blends, respectively. PE‐g‐MA and POE‐g‐MA reinforced the tensile stress and toughness of the blends. The toughness value of POE‐g‐MA incorporating blends was the highest, reached to 2032.3 MJ/m³, while that of the control was only 1402.9 MJ/m³. Therefore, POE‐g‐MA was selected as asphalt modifier. The toughness value reached to the highest level when the content of POE‐g‐MA was about 8%. Besides that the softening point of the modified asphalt would be higher than 60°C, whereas the content of WTP/LDPE blend was more than 5%, and the blends were mixed by stirring under the shearing speed of 3000 rpm for 20 min. Especially, when the blend content was 8.5%, the softening point arrived at 82°C, contributing to asphalt strength and elastic properties in a wide range of temperature. In addition, the swelling property of POE‐g‐MA/WTP/LDPE blend was better than that of the other compalibitizers, which indicated that POE‐g‐MA /WTP/LDPE blend was much compatible with asphalt. Also, the excellent compatibility would result in the good mechanical and processing properties of the modified asphalt. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of different compatibilizers on the rheological,thermomechanical, and morphological properties of HDPE/LLDPE blend‐based nanocomposites

The influence of two different compatibilizers and their combination (maleic anhydride grafted high density polyethylene, HDPE‐g‐MA; maleic anhydride grafted linear low density polyethylene, LLDPE‐g‐MA; and 50/50 wt % mixture of these compatibilizers) on the rheological, thermomechanical, and morphological properties of HDPE/LLDPE/organoclay blend‐based nanocomposites was evaluated. Nanocomposites were obtained by melt‐intercalation in a torque rheometer in two steps. Masterbatches (compatibilizer/nanoclay 2:1) were obtained and subsequently diluted in the HDPE/LLDPE matrix producing nanocomposites with 2.5 wt % of nanoclay. Wide angle X‐ray diffraction (WAXD), steady‐state rheological properties, and transmission electron microscopy (TEM) were used to determine the influence of different compatibilizer systems on intercalation and/or exfoliation process which occurs preferentially in the amorphous phase, and thermomechanical properties. The LLDPE‐g‐MA with a high melt index (and consequently low viscosity and crystallinity) was an effective compatibilizer for this system. Furthermore, the compatibilized nanocomposites with LLDPE‐g‐MA or mixture of HDPE‐g‐MA and LLDPE‐g‐MA exhibited better nanoclay's dispersion and distribution with stronger interactions between the matrix and the nanoclay. These results indicated that the addition of maleic anhydride grafted polyethylene facilitates both, the exfoliation and/or intercalation of the clays and its adhesion to HDPE/LLDPE blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1726–1735, 2013     

Influence of in situ compatibilization on in situ formation of low‐density polyethylene/polyamide 6 blends by reactive extrusion

Low‐density polyethylene/polyamide 6 (LDPE/PA6) blends were in situ formed by reactive extrusion, in which in situ polymerization of ε‐caprolactam (CL) and in situ copolymerization of maleic anhydride grafted low‐density polyethylene (LDPE‐MA) and CL took place simultaneously. The latter reaction could be considered as in situ compatibilization, and the influence of in situ compatibilization on the morphologies, thermal properties, and rheological behaviors of the blends was investigated in this work. Scanning electron microscopy showed that the in situ compatibilization could dramatically reduce the dispersed phase sizes and narrow the size distribution. The thermal properties indicated that in differential scanning calorimetry (DSC) cooling scans, fractionated crystallization of the PA6 component was observed in all cases and was promoted with increasing the amount of LDPE‐MA. The DSC second heating scans showed the in situ compatibilization could stimulate the formation of the less stable γ‐crystalline form of PA6 in the blends. Dynamic rheological experiments revealed the in situ compatibilization had enhanced the viscosity, storage modulus, and loss modulus of the blend and reduce the corresponding slope values of the storage modulus and loss modulus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal properties and morphology of recycled poly(ethylene terephthalate)/maleic anhydride grafted linear low‐density polyethylene blends

Properties of recycled Poly(ethylene terephthalate) were greatly improved. Recycled PET was blended with LLDPE‐g‐MA by low‐temperature solid‐state extrusion. Mechanical properties of the blends were affected obviously by the added LLDPE‐g‐MA. Elongation at break reaches 352.8% when the blend contains 10 wt % LLDPE‐g‐MA. Crystallization behavior of PET phase was affected by LLDPE‐g‐MA content. Crystallinity of PET decreased with the increase of LLDPE‐g‐MA content. FTIR testified that maleic anhydride group in LLDPE‐g‐MA reacted with the end hydroxyl groups of PET and PET‐co‐LLDPE‐g‐MA copolymers were in situ synthesized. SEM micrographs display that LLDPE‐g‐MA phase and PET phase are incompatible and the compatibility of the blends can be improved by the forming of PET‐co‐LLDPE‐g‐MA copolymer. LLDPE‐g‐MA content was less, the LLDPE‐g‐MA phase dispersed in PET matrix fine. With the increase of LLDPE‐g‐MA content, the morphology of dispersed LLDPE‐g‐MA phase changed from spherule to cigar bar, then to irregular spherule. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of maleated syndiotactic polystyrene on the morphology,mechanical properties,and crystallization behavior of syndiotactic polystyrene/polyamide 6 blends

The compatibilization of syndiotactic polystyrene (sPS)/polyamide 6 (PA‐6) blends with maleic anhydride grafted syndiotactic polystyrene (sPS‐g‐MA) as a reactive compatibilizer was investigated. The sPS/PA‐6 blends were in situ compatibilized by a reaction between the maleic anhydride (MA) of sPS‐g‐MA and the amine end group of PA‐6. The occurrence of the chemical reaction was substantiated by the disappearance of a characteristic MA peak from the Fourier transform infrared spectrum. Morphology observations showed that the size of the dispersed PA‐6 domains was significantly reduced and that the interfacial adhesion was much improved by the addition of sPS‐g‐MA. As a result of reactive compatibilization, the impact strengths of the sPS/PA‐6 blends increased with an increase in the sPS‐g‐MA content. The crystallization behaviors of the blends were affected by the compatibilization effect of sPS‐g‐MA. A single melting peak of sPS in the noncompatibilized blend was gradually split into two peaks as the amount of the compatibilizer increased. A single crystallization peak of PA‐6 in the noncompatibilized blend became two peaks with the addition of 3 wt % sPS‐g‐MA. The new peak was a result of the fractionation crystallization. As the amount of sPS‐g‐MA increased, the intensity of the new peak increased, and the original peak nearly disappeared. Finally, the crystallization peak of PA‐6 disappeared with 20 wt % sPS‐g‐MA in the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2502–2506, 2003     

Effects of addition of acrylic compatibilizer on the morphology and mechanical behavior of amorphous polyamide/SAN blends

Amorphous polyamide (aPA)/acrylonitrile‐styrene copolymer (SAN) blends were prepared using methyl methacrylate‐maleic anhydride copolymer MMA‐MA as compatibilizer. The aPA/SAN blends can be considered as a less complex version of the aPA/ABS (acrylonitrilebutadiene‐styrene) blends, due to the absence of the ABS rubber phase in the SAN material. It is known that acrylic copolymer might be miscible with SAN, whereas the maleic anhydride groups from MMA‐MA can react in situ with the amine end groups of aPA during melt blending. As a result, it is possible the in situ formation of aPA‐g‐MMA‐MA grafted copolymers at the aPA/SAN interface during the melt processing of the blends. In this study, the MA content in the MMA‐MA copolymer and its molecular weight was varied independently and their effects on the blend morphology and stress–strain behavior were evaluated. The morphology of the blends aPA/SAN showed a minimum in the SAN particle size at low amounts of MA in the compatibilizer, however, as the MA content in the MMA‐MA copolymer was increased larger SAN particle sizes were observed in the systems. In addition, higher MA content in the compatibilizer lead to less ductile aPA/SAN blends under tensile testing. The results shown the viscosity ratio also plays a very important role in the morphology formation and consequently on the properties of the aPA/SAN blends studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical properties and morphology of polylactide,linear low‐density polyethylene,and their blends

Melt blending of linear low density polyethylene (LLDPE) and polylactide (PLA) was performed in an extrusion mixer with post extrusion blown film attachment with and without compatibilizer‐grafted low density polyethylene maleic anhydride. The blend compositions were optimized for tensile properties as per ASTM D 882‐91. On the basis of this, LLDPE 80 [80 wt % LLDPE and 20 wt % poly(L ‐lactic acid) (PLLA)] and MA‐g‐low‐density polyethylene 80/4 (80 wt % LLDPE, 20 wt % PLLA, and 4 phr compatibilizer) were found to be an optimum composition. The blends were characterized according to their mechanical, thermal, and morphological behavior. Fourier transform infrared spectroscopy revealed that the presence of compatibilizer enhanced the blend compatibility to some extent. The morphological characteristics of the blends with and without compatibilizer were examined by scanning electron microscopy. The dispersion of PLLA in the LLDPE matrix increased with the addition of compatibilizer. This blend may be used for packaging applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Toughening of polyamide 11 via addition of crystallizable polyethylene derivatives

BACKGROUND: Conventional rubber‐like toughening modifiers are soft and amorphous, and when used to toughen polyamide 11 (PA11) they commonly induce a decrease in the tensile strength and modulus. In this study, crystallizable polyethylene (PE) derivatives, i.e. linear low‐density polyethylene (LLDPE) and maleic anhydride‐grafted polyethylene (PE‐g‐MA), were adopted to toughen PA11. RESULTS: Compared to pure PA11, a highest improvement by a factor of eight in the impact toughness was achieved; also, the tensile strength and modulus could be maintained at a relatively high level. PE‐g‐MA acted as a compatibilizer for PA11 and LLDPE, bringing strong interfacial adherence, and especially a domain‐in‐domain morphology observed in PA11/PE‐g‐MA/LLDPE (70/10/20 by weight) blends. The observation that PA11 was toughened by the crystallizable PE derivatives is discussed in depth, based on the combined effect of surface crystallization of LLDPE on pre‐formed PA11 crystallites and interfacial compatiblization between PA11 and PE‐g‐MA. CONCLUSION: The crystallizable PE derivatives LLDPE and PE‐g‐MA were shown to be effective toughening modifiers for the proportions PA11/PE‐g‐MA/LLDPE 70/10/20 (by weight), which is considered to be an optimum composition: special domain‐in‐domain morphology was observed indicating a good dispersion of PE in the PA11 matrix and strong interfacial adherence between PE phase and PA11 phase. The reason why strength and modulus were maintained at a high level in the as‐prepared blends was attributed to the existence of rigid crystalline domains in PE. Copyright © 2009 Society of Chemical Industry     

Rubber toughened polyamide 6: The influences of compatibilizer on morphology and impact properties

In this study, styrene-(ethylene-co-butylene)-styrene (SEBS) triblock copolymer (Kraton G-1652) was modified with maleic anhydride (MA). The maleated SEBS was used as compatibilizer for the blends of Nylon 6 (PA6) and SEBS. The morphology and impact strength of the blends were measured as functions of concentration and MA graft ratio of maleated SEBS. The compatibility and fracture mechanism of the blends were evaluated from the SEM micrographs of the xylene-etched surfaces and of fractured surfaces. Some of the blends exhibited an impact strength up to about 30 fold greater than neat PA6. The fracture involved both both cavitation and shear yielding. The mechanism of compatibilization of maleated SEBS in the ternary components blends was proposed.     

Modification of LLDPE using esterified styrene maleic anhydride copolymer: Study of its properties and environmental degradability

Linear low‐density polyethylene (LLDPE) was blended with decanol‐esterified styrene maleic anhydride copolymer (MDESMA) with an aim to enhance the environmental degradability of polyethylenes. Styrene‐maleic anhydride copolymer (SMA) was synthesized by precipitation polymerization, using benzoyl peroxide (BPO) as initiator. SMA was esterified with a long‐chain monoalcohol, n‐decanol, using methyl ethyl ketone (MEK) as solvent at 80°C to obtain monoesterified styrene‐maleic anhydride (MDESMA). Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA) were performed to characterize SMA and MDESMA. IR spectra of MDESMA showed a decrease in intensity of peak responsible for carbonyl absorption of a five‐membered ring anhydride group along with broadening of carboxyl O? H stretching peak. TGA showed two‐stage degradation for SMA and MDESMA. LLDPE was blended with MDESMA in single‐screw extruder and blends were characterized thermally by DSC and TGA. A single endothermic melting peak of LLDPE/MDESMA blend was observed. Films of the blends, formed by compression molding, showed an increase in modulus of elasticity but a decrease in elongation at break with increasing concentration of MDESMA. LLDPE/MDESMA blend compositions when kept in phosphate/citric acid buffer solution (pH ～ 8) showed initial weight gain because of water absorption and subsequently loss in weight due to dissolution of soluble component of blends. Film samples of blends kept for soil burial also showed similar behavior. Contact‐angle measurement of film samples of the blends showed an increase in value on soil burial, indicating degradation/dissolution of MDESMA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 102–108, 2004     

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     

Preparation of the HIPS/MA graft copolymer and its compatibilization in HIPS/PA1010 blends

The graft copolymer of high‐impact polystyrene (HIPS) grafted with maleic anhydride (MA) (HIPS‐g‐MA) was prepared with melt mixing in the presence of a free‐radical initiator. The grafting reaction was confirmed by infrared analyses, and the amount of MA grafted on HIPS was evaluated by a titration method. 1–5% of MA can be grafted on HIPS. HIPS‐g‐MA is miscible with HIPS. Its anhydride group can react with polyamide 1010 (PA1010) during melt mixing of the two components. The compatibility of HIPS‐g‐MA in the HIPS/PA1010 blends was evident. Evidence of reactions in the blends was confirmed in the morphology and mechanical behavior of the blends. A significant reduction in domain size was observed because of the compatibilization of HIPS‐g‐MA in the blends of HIPS and PA1010. The tensile mechanical properties of the prepared blends were investigated, and the fracture surfaces of the blends were examined by means of the scanning electron microscope. The improved adhesion in a 15% HIPS/75% PA1010 blend with 10% HIPS‐g‐MA copolymer was detected. The morphology of fibrillar ligaments formed by PA1010 connecting HIPS particles was observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2017–2025, 1999