Conceptualizing Physical and Chemical Interactions in the Compatibilized HDPE/PA6 and HDPE/EVOH Pairs: Theoretical and Experimental Analyses

Physical/chemical interaction in blends of high-density polyethylene with polyamide 6 and polyethylene-co-vinyl alcohol compatibilized with maleic anhydride-grafted high-density polyethylene was discussed. The performance of maleic anhydride-grafted high-density polyethylene was assessed by domain size variation and interfacial adhesion examination. Analysis of impact strength elucidated physical interaction improvement by compatibilization (entanglements and hydrogen bonding), while chemical reactions between ?OH and ?NH (from polyethylene-co-vinyl alcohol and polyamide 6, respectively) and ?COOH functional groups resulting from ring-opening of maleic anhydride determined interfacial adhesion reinforcement, where interfacial adhesion parameter changed from 0.75 for noncompatibilized to 0.96 compatibilized high-density polyethylene/polyamide 6, but remained unchanged for high-density polyethylene/polyethylene-co-vinyl alcohol blends, from 0.98 to 1.02.     

Fusion bonding of maleated polyethylene blends to polyamide 6

Blends of linear low-density polyethylene (LLDPE) and linear low-density polyethylene–grafted maleic anhydride (LLDPE-gMA) were used to promote the adhesion to polyamide 6 (PA) in a three-layer coextruded film without using an additional adhesive or tie layer. The effect of bonding time and molecular weight (MW) of different maleated polyethylenes on the peel strength of the joints was analyzed. Direct evidence of a copolymer formed in-situ at the interfaces is also considered. The peel strength of fusion bonded layers of LLDPE/LLDPE-gMA blends with PA strongly depends on bonding time and molecular weight of the maleated polymer. Tensile properties of three-layer films, made up of PA as the central layer and LLDPE/LLDPE-gMA blends as the two external layers, are improved with increases in the maleic anhydride (MA) content in the blend. The in-situ formation of a copolymer between the MA in the blend and the terminal amine groups of the PA was confirmed by the Molau test, infrared (IR) spectroscopy, and thermal analysis (DSC).     

Relationship between interfacial tension and dispersed‐phase particle size in polymer blends. II. PP/PA6

Simple blends with different viscosity ratios of the components as well as compatibilized blends varying both in type and content of the compatibilizers were used to study the relation between the interfacial tension and the dispersed‐phase particle size for PP/PA6 (80/20 wt %) blends in this work. Four compatibilizing systems including poly(ethylene‐co‐methacrylic acid) ionomers, a maleic anhydride‐grafted propylene copolymer, maleic anhydride‐grafted polypropylene, and a maleic anhydride‐grafted styrene ethylene butylene copolymer were used. For blends prepared in an internal mixer, a power‐law relation was found between the capillary number and the torque ratio of the blends' components. This relation was used to estimate the interfacial tension for the compatibilized blends. The relation between the steady‐state torque of the blends as a measure of viscosity and the estimated values of interfacial tension were also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 54–63, 2003     

Low-density polyethylene/polyamide 6 blends from multilayer films waste

Multilayer films combine properties of different polymers in a single material, attending specifications to applications such as packaging. However, the mechanical recycling for this material king is commercially less interesting because the polymeric components cannot easily be separated and the direct mechanical processing of the material leads to the immiscible and incompatible polymeric blends. The aim of this study was to evaluate properties of the blends of low-density polyethylene (LDPE) and polyamide 6 (PA6) generated from mechanical recycling of multilayer films constituted by LDPE and PA6, containing maleic anhydride grafted polyethylene (PE-g-MA) as compatibilizing agent and different amounts of virgin PA6. The LDPE/PA6 blends are immiscible for all composition and the use of PE-g-MA has showed little effect on the compatibility of the blends with high content of PA6. However, LDPE/PA6 blends with PA6 content up to 20 wt % showed considerable performance for mechanical performance that can justify the mechanical recycling of the material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47456     

Binary and ternary blends of polyethylene,polypropylene, and polyamide 6,6: The effect of compatibilization on the morphology and rheology

The effects of two compatibilizing agents, polystyrene–poly(ethylene butylene)–polystyrene copolymer (SEBS) and SEBS‐grafted maleic anhydride (SEBS‐g‐MAH), on the morphology of binary and ternary blends of polyethylene, polypropylene, and polyamide 6,6 were investigated with scanning electron microscopy and melt rheology measurements. The addition of the compatibilizers led to finer dispersions of the particles of the minor component and a decrease in their size; this induced a significant change in the blend morphology. The rheological measurements confirmed the increased interaction between the blend components, especially with SEBS‐g‐MAH as the compatibilizer. New covalent bonds could be expected to form through an amine–anhydride reaction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1976–1985, 2004     

Compatibilization and toughening of immiscible ternary blends of polyamide 6, polypropylene (or a propylene—Ethylene copolymer), and polystyrene

In this work, typical ternary blends of three versatile polymers—polyamide 6, a propylene–ethylene copolymer (co‐PP), and polystyrene—were studied. As a compatibilizer, co‐PP with randomly dispersed minor ethylene units was multimonomer‐melt‐grafted in the presence of maleic anhydride, styrene, and dicumyl peroxide. The influence of the ethylene content in co‐PP and the blend composition on the performance was investigated. Scanning electron microscopy images showed an obvious decrease in the droplet size of the dispersed phase with increases in the compatibilizer content and number of ethylene units in co‐PP. Peaks of tan δ/temperature curves approaching the glass‐transition temperatures of the components were observed with dynamic mechanical thermal analysis. The improved mechanical properties implied good compatibility of the components in the blends. Significant toughening was achieved when the concentration of co‐PP was increased from 15 to 25 wt %: the elongation at break of the compatibilized blends increased dozens of times in comparison with the elongation at break of the uncompatibilized blends. The introduction of the multimonomer‐melt‐grafted co‐PP was shown to be an effective approach for improving immiscible multipolymer blends and to have practical potential. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of polyamide 6/polypropylene–vermiculite nanocomposite/polyamide 6 alloys

Polypropylene–vermiculite nanocomposites can be achieved by simple melt mixing of maleic anhydride‐modified vermiculite with polypropylene. Maleic anhydride acts either as a compatibilizer for the polymeric matrix or as a swelling agent for the silicate. Compatibilized blends are injection molded directly from polyamide 6 and polypropylene–vermiculite nanocomposites. Scanning electron microscopy observation reveals that a two‐phase structure consisting of polypropylene–vermiculite nanocomposite and polyamide 6 is formed in the blends. The absence of vermiculite reflections in the X‐ray powder diffraction patterns indicates that the polypropylene–vermiculite phase exhibits nanocomposite characteristics. Tensile test shows that the tensile modulus of the polymer alloy tends to increase with increasing polypropylene–vermiculite nanocomposite content. The tensile strength of composite containing 8 wt % vermiculite is higher than that of pure polyamide 6. Finally, the thermal properties of the nanocomposites are determined by dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric measurements. The effects of maleic anhydride addition on the formation of polypropylene–vermiculite nanocomposite reinforcement and on the mechanical properties of composites are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2330–2337, 2002     

The effect of zinc oxide addition on the compatibilization efficiency of maleic anhydride grafted high‐density polyethylene compatibilizer for high‐density polyethylene/polyamide 6 blends

A high‐density polyethylene with grafted maleic anhydride units has been investigated as a compatibilizer for high‐density polyethylene with polyamide 6. The material acts as an effective compatibilizer, causing a marked reduction in dispersed phase size as well as an increase in tensile strength and toughness. Compatibilizer also affects the glass‐transition temperature, crystallization kinetics, and amount of crystalline material for certain blend compositions. The addition of zinc cations, which are effective in increasing ethylene‐acid copolymer compatibilizer performance in low‐density polyethylene/polyamide blends, has little, if any, effect on compatibilizer performance in these high‐density polyethylene/polyamide blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3871–3881, 2007     

Compatibility effect of reactive copolymers on polypropylene/polyamide 6 blends from commingled plastic wastes

We report the compatibility effect on a recycled polypropylene/nylon (75/25) blend processed with reactive copolymers on the basis of morphological, mechanical, and rheological characteristics. Via a scanning electron microscopy investigation, we found improved surface morphologies with regular and fine domains in a recycled polypropylene/nylon (75/25) blend compatibilized with copolymers containing maleic anhydride as a reactive functional group [styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer and polypropylene‐graft‐maleic anhydride]. Large increases in both the mechanical and rheological properties with the addition of the styrene–(ethylene/butylene)–styrene‐graft‐maleic anhydride copolymer could be interpreted with respect to a specific structure at the interface, showing a strong interfacial adhesion between recycled polypropylene and nylon. To confirm the existence of this structure, we used various dynamic rheological parameters: the Cox–Merz rule, storage modulus, and phase angle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1188–1193, 2006     

Industrial waste origin succinic anhydride‐grafted atactic polypropylene as compatibilizer of full range polypropylene/polyamide 6 blends as revealed by dynamic mechanical analysis at the polypropylene glass transition

This work deals with a dynamic mechanical analysis (DMA) study on the effect of a novel interfacial agent containing maleated grafts on an industrial waste origin atactic polypropylene. This contains 3% of bridge‐, backbone‐, and terminal‐grafted succinic anhydride groups (aPP‐SA/SA). By considering a polymer blend as a special case of composite where the dispersed phase is mobile, it is assumed that both the amounts of polyamide 6 (PA6) and the interfacial agent (aPP‐SA/SA) cause changes in the glass transition temperature of the polypropylene phase in the blend. In this work, we have used DMA parameters to evidence the real interfacial modifications caused by the presence of aPP‐SA/SA in the isotactic polypropylene (iPP)/PA6 system at the iPP glass transition temperature on the basis that this is an unfavorable scenario for the action of aPP‐SA/SA. Since each component of the blend is interacting with each other, and to include the influence of the dispersed phase, it is possible to use a Box–Wilson experimental design model by resembling the so‐called “agent based models” to obtain algorithms forecasting the dynamic mechanical parameters (storage, E’, and loss moduli, E”) at the glass transition of iPP, in all the composition range of whatever iPP/PA6/aPP‐SA/SA‐modified blend. POLYM. ENG. SCI., 59:2458–2466, 2019. © 2019 Society of Plastics Engineers     

Polyethylene/polyamide-6 blends containing mercapto-modified EVA

The effect of poly(ethylene-co-vinyl alcohol-co-vinyl mercaptoacetate) (EVASH) on the compatibilization of nylon-6 (PA6)/low-density polyethylene (LDPE) was investigated. EVASH was prepared from hydrolyzed EVA through an esterification reaction with mer-captoacetic acid. Mechanical properties, differential scanning calorimetry, and scanning electron microscopy results are discussed. The mechanical properties were improved with the addition of EVASH. The compatibilizing agent also affects the crystallinity degree of both components of the blend, as indicated by the results obtained from DSC studies. The addition of EVASH results in a reduced dispersed-phase particle size. © 1996 John Wiley & Sons, Inc.     

Rheological properties,crystallization, and morphology of compatibilized blends of isotactic polypropylene and polyamide

Blends of isotactic polypropylene (iPP) with the polyamide nylon-6 (N6), prepared by extrusion, were studied with a composition of up to 30% by weight polyamide. In the case of a 70/30 iPP/N6 blend, the influence of a compatibilizing agent based on polypropylene functionalized with maleic anhydride (PP-g-MA), with compositions of 1, 3, 5, and 10% by weight in polypropylene, was followed. The influence of the concentration of N6 and the compatibilizing agent on the rheological and thermal properties, and the morphology of the blends, was analyzed by monitoring the melt viscosity at different shear rates, differential scanning calorimetry, and polarized light microscopy. Vibrational spectroscopy was used to characterize the blends and to study the effect of the compatibilizing agent. The viscosity—composition curves for the iPP/N6 blends, in the composition and shear rate ranges analyzed, show a negative deviation from the additive rule, while the opposite trend is observed for the blends compatibilized with PP-g-MA. Important variations in the spectroscopic behavior was observed between compatibilized and noncompatibilized blends, which varied as a function of the compatibilizing agent concentration. The crystallization rates of iPP in the iPP/N6 blends, under both dynamic and isothermal conditions, are much greater than are those observed for pure iPP and are directly related to the nucleating activity of the polyamide. This effect is much smaller in the presence of the compatibilizing agent. The isothermal crystallization of the polyamide N6 in compatibilized blends is affected by the presence of iPP, reducing the crystallization rate due to the diluent effect of the polypropylene. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2665–2677, 1997     

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.     

Reactive blending of functionalized polypropylene and polyamide 6: In situ polymerization and in situ compatibilization

Compatibilized polypropylene/polyamide 6 blends were prepared with polypropylene, ε‐caprolactam and maleic anhydride grafted polypropylene via in situ polymerization and in situ compatibilization in a batch mixer. Scanning electron microscopy and differential scanning calorimetric analysis showed that the compatibilizing effect was significantly enhanced through use of this method compared to the classic method of blending premade polymers. The optimum processing parameters were obtained for the reactive blends and the effect of maleic anhydride grafted polypropylene content, and the effect of relative weight fraction of maleic anhydride grafted polypropylene to ε‐caprolactam on the overall morphology of the blend system was investigated. It was found that the domain sizes of the polypropylene and polyamide components in the blends could be easily controlled through proper management of the polymerization and compatibilizing reactions during processing. Polym. Eng. Sci. 44:648–659, 2004. © 2004 Society of Plastics Engineers.     

Preparation and applicability of functionalized polyethylene with an ethylene/1,7‐octadiene copolymer

The copolymerization of ethylene and 1,7‐octadiene was carried out to synthesize polyethylene with unreacted vinyl groups. The prepared copolymer [poly (ethylene‐co‐1,7‐octadiene) (PEOD)] was epoxidized with peracetic acid, m‐chloroperbenzoic acid, or formic acid/H₂O₂. Of these, peracetic acid gave the best results. Epoxidized PEOD was subjected to a reaction with 2‐mercaptobenzimidazole and poly(L ‐lactic acid). The bromination of PEOD was also performed in the presence of a Br₂/HBr solution at room temperature. The brominated poly(ethylene‐co‐1,7‐octadiene) (PEOD‐Br) was used as a macroinitiator for atom transfer radical polymerization. The polymerization of styrene, butyl methacrylate, and glycidyl methacrylate was performed in bulk or solution at 120°C with a PEOD‐Br/CuBr/2,2′‐dipyridyl initiator system. The thermal properties of the graft copolymers and the efficiency of the graft polymerization were investigated. These graft copolymers have potential applications as interfacial modifiers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Melt‐state miscibility of poly(ethylene‐co‐1‐octene) and linear polyethylene

On purpose to examine the effect of branch length on the miscibility of polyolefin blends, miscibility behavior of linear polyethylene/poly(ethylene‐co‐1‐octene) blend was studied and compared to that of linear polyethylene/poly(ethylene‐co‐1‐butene) blend. Miscibility of the blend was determined by observing the morphology quenched from the melt, and by using the relation between interaction parameter and copolymer composition. When the weight composition and molecular weight was the same, poly(ethylene‐co‐1‐octene) was slightly more miscible with linear polyethylene than poly(ethylene‐co‐1‐butene) was. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of a structured acrylic impact modifier and its application in toughening polyamide 6

A series of poly(n‐butyl acrylate)/poly(methyl methacrylate‐co‐acrylic acid), i.e., poly(BA/MMA‐co‐AA), core‐shell structured modifiers with different contents of crosslinking agent allyl methacrylate and functional monomer were prepared, and its effects on mechanical properties of polyamide 6 (PA 6) blends were investigated. The modifiers were prepared at a solid content of 50 wt% by a seeded emulsion polymerization. Dynamic light scattering measurement showed that the particle grew without significant secondary nucleation occurring. The morphology was confirmed by means of transmission electron microscopy. Scanning electron microscopy was used to observe the morphology of the fractured surfaces. The dynamic mechanical analysis measurements indicated that the appearance of two merged transition peaks and the magnitude of the loss peak of PA 6 matrix with the addition of PBMA core‐shell modifier in the PA 6/PBMA blends were responsible for the improvement of PA 6 toughness. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Dynamic rheological behavior of reactively compatibilized polypropylene/polyamide 6 blending melts

The dynamic rheological behavior is measured by small amplitude oscillatory shear on rotational rheometer for polypropylene/polyamide 6 (PP/PA6) blends compatibilized by a polypropylene grafted maleic anhydride (PP‐g‐MAH). Scanning electron microscope (SEM) results show that the PP/PP‐g‐MAH/PA6 (=100/6/40wt) is sea‐island structure, the PP/PP‐g‐MAH/PA6 (=100/6/60wt) blend is semi‐cocontinuous. Coarse PA6 zones can be observed when the weight ratio is 100/6/80. At low frequency the complex viscosity, dynamic modulus of the PP/PP‐g‐MAH/PA6 (PP/PP‐g‐MAH = 100/6wt) blends first increase then drop with the increase of PA6 weight content in the range of 0–100, the maximum value arrives at the weight content of 60. The Cole–Cole plots as well as the weighted relaxation spectra of the blends have a main arc and a tail when the weight ratio of PP/PP‐g‐MAH/PA6 is in the range of 100/6/20–100/6/60, but have different shapes when the weight ratio increases to 100/6/80 and 100/6/100. The possible reason is the weight ratio of 100/6/80 and 100/6/100 is close to the phase inversion point. In fitting the storage modulus data at low frequency, Palierne's model with two parameters interfacial tension and interfacial shear modulus is better than Bousmina's model. Palierne's model with only one parameter of interfacial tension can not fit the data well. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42091.     

Oxygen barrier properties of polypropylene/polyamide 6 blends

Effects of composition, compatibilization, and blending procedure on oxygen barrier properties of injection-molded polypropylene/polyamide 6 blends were investigated. The main attention was paid to the relationships between oxygen permeability, mechanical properties, and blend morphology. The effect of the polypropylene/polyamide 6 ratio was evident in blends with a homogeneous dispersion type of morphology. After the phase inversion, when polyamide became the continuous phase, the barrier properties of the blends were significantly improved and approached those of polyamide 6. Increasing the amount of the compatibilizer, maleic anhydride grafted polypropylene, was found to increase the permeability of the blend. The blending procedure had a significant effect on the permeability of the blends. The injection-molded blend exhibited a laminar type of morphology when polyamide 6 and the compatibilizer were preblended in a twin-screw extruder, and polypropylene was added later as a dry-blend before injection molding. The dispersed polyamide phase formed thin elongated platelets in the polypropylene matrix. This laminar morphology resulted in significant improvement of oxygen barrier properties approaching the level of the theoretical values calculated for corresponding coextruded structures. Moreover, both the tensile and impact properties of this particular blend were exceptionally good. © 1995 John Wiley & Sons, Inc.     

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