Polyethylene Compatibilizer Research Articles

Mechano Chemical Compatibilization of Polyethylene with Graphite by Means of a Suitable Ester.

An effective non-covalent compatibilization method for graphite and low-density polyethylene is reported. To obtain this result, pyren-1-yl-stearate (P1S) was synthesized, characterized and mixed with graphite to provide a better dispersion in polyethylene matrix. The P1S improves the dispersion of carbon filler in polyethylene through non-covalent compatibilization: the pyrenyl group gives π-π stacking interactions with graphite and the stearyl chain provides van der Waals interaction with the polymer chain (specifically London dispersion forces). In this study, different P1S/graphite fillers were prepared with a ratio by weight of 90/10 and 50/50, respectively, by using manual and ball-milling mixing. Their stability, interaction and morphology were evaluated through TGA, RX, and SEM. Thermogravimetric analyses showed that ball-milling mixing is more effective than manual mixing in promoting π-π stacking interactions of molecules such as P1S ester containing an alkyl chain and aromatic rings. The role of ball milling is confirmed by X-ray diffraction measurements since it was possible to observe both exfoliation and intercalation phenomena when this technique was used to mix the P1S ester with graphite. SEM analyses of polyethylene containing 1% of the carbon fillers again highlighted the importance of ball milling to promote the interaction of the ester with graphite and, simultaneously, the importance of the alkyl chain in order to achieve polyethylene-graphite compatibilization.

Compatibilization of iPP/HDPE Blends with PE-g-iPP Graft Copolymers.

The compatibilization of polyethylene (PE) and isotactic polypropylene (iPP) blends is of particular interest due to the challenges associated with recycling these plastics from mixed waste streams. Polyethylene-graft-iPP copolymers (PE-g-iPP) were prepared using a grafting-through strategy by copolymerization of ethylene with allyl-terminated iPP macromonomers in the presence of a hafnium pyridylamido catalyst. Graft copolymers with a variety of graft lengths (Mn = 6-28 kg/mol), graft numbers, and graft spacings were prepared. These graft copolymers were melt-blended with high-density polyethylene (HDPE) and iPP (iPP/HDPE = 30/70 w/w), and the blend properties were evaluated by tensile testing. The blends showed enhanced tensile strength at 5 and 1 wt % loading, with higher tensile strength observed for larger block numbers and graft lengths. These results indicate that graft copolymers are efficient compatibilizers for blends of HDPE and iPP.

Experimental and MD simulation study on the physical and mechanical properties of organically modified montmorillonite clay and compatibilized linear low density polyethylene nanocomposites

ABSTRACTUnderstanding the interfacial interactions plays a key role in controlling mechanical and physical properties of polymer/clay nanocomposites (PCNs). In this work, the surface interactions between constituents of experimentally prepared PCNs which are the pristine linear low density polyethylene (PE) chains, PE compatibilizers, montmorillonite clay surface layer, and surfactants were studied quantitatively by employing molecular dynamics simulation technique. The interaction energy between the polymer and the clay was found to be inversely proportional with the volume of the surfactant which decreases the electrostatic interactions between the compatibilizer and the hydrophilic clay surface. However, the van der Waals (vdW) interactions between alkyl tails of surfactants and the PE chains increase with the tail length of the surfactants. The most attractive interaction was between the surfactant's head group and the clay surface. We showed that there existed fine balance between the electrostatic and vdW type forces on the stability and the enhanced properties of the PE–organoclay nanocomposites. Calculated interaction energies were then correlated to the experimentally measured mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45817.

The effect of sepiolite on the compatibilization of polyethylene–thermoplastic starch blends for environmentally friendly films

Green polyethylene is a new and attracting polymer from biobased resources (sugarcane) and identical properties to petroleum-based polyethylene. Its potential in the packaging industry is really promising. In this work, we report the use of different compatibilizer systems for green polyethylene (from sugarcane) and thermoplastic starch (30 wt% TPS) in order to increase ductile mechanical properties and biodegradable content. Typical petroleum-based graft copolymer of polyethylene with maleic anhydride (PE-g-MA) is used as reference compatibilizer, and new compatibilizer systems are developed using sepiolite. The obtained results show that sepiolite-based compatibilizers provide good compatibilization properties as observed by a remarkable increase in elongation at break and a noticeable size reduction of the TPS domains dispersed in the green polyethylene matrix as observed by scanning electron microscopy (SEM).

Properties of wood-polymer composites with a polymer matrix containing sevilens

The effect of vinylacetate unit content in sevilen used as a polymer matrix or polyethylene compatibilizer on the properties of wood-polymer composites with a thermoplastic binders and filler of plant origin is studied. It is shown that the introduction of vinylacetate units decreases the tensile strength, contact elastic modulus, Brinell hardness, and water absorption of the composites, but increases the relative tensile elongation and impact viscosity without notch.

Dielectric Properties of PE/Clay Nanocomposites

Polyethylene/nanoclay specimens containing from 0 to 5% nanoclays were prepared from a commercially available premixed PE/nanoclay masterbatch containing 50% wt of nanoclay. The masterbatch was diluted to the desired concentration by adding PE along with various amounts of compatibilizer in order to achieve the best possible dispersion of the nanoclay platelets. The dielectric response of the compounded samples was investigated using a combination of time and frequency‐domain spectroscopy in order to cover a wide frequency window. Both techniques were in good agreement when the time‐domain data was transformed into frequency‐domain data. Despite their low concentration, the addition of the dispersed nanoclays led to a significant alteration of the material dielectric response in the form of the appearance of various interfacial relaxation processes and an increase of charge carrier transport within the insulation material. Moreover, an onset of nonlinear charge transport process was observed at moderate fields for specimens containing a relatively low level of nanoclays. The high‐field breakdown strength was shown to have been improved by the incorporation of the nanoparticles, particularly when the exfoliation was enhanced by the use of a maleic anhydride grafted polyethylene compatibilizer.

Melt-neutralization of maleic anhydride grafted on high-density polyethylene compatibilizer for polyamide-6/high-density polyethylene blend: effect of neutralization level on compatibility of the blend

Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.

High‐density polyethylene nanocomposites using masterbatches of chlorinated polyethylene/graphene oxide

AbstractGraphene‐based nanocomposites were generated by solution mixing of the graphene oxide filler with chlorinated polyethylene compatibilizers followed by melt mixing of the solution mixed masterbatches with high‐density polyethylene. Compatibilizers with two different chlorination contents were used in different amounts in order to analyze their effect on the morphology and properties of resulting nanocomposites. Peak melting point as well as overall crystallinity was affected by graphene oxide as well as compatibilizers. Compatibilizer with higher chlorination content also interacted with polar graphene oxide surface more effectively thus leading to better filler dispersion in the composites. The addition of compatibilizers to the composites resulted in their shear and processing stability at higher angular frequencies and temperature, which otherwise was not possible for pure polymer as well as composites without compatibilizer. The mechanical performance of the nanocomposites at ambient conditions was also affected by the factors like filler delamination, plasticization of the matrix, compatibilizer content as well as their chlorination level and amorphous/semicrystalline nature. An increase of 16% in tensile modulus and 21% in strength of the composites with 5 wt% of 25% chlorinated compatibilizer at 0.5 wt% graphene oxide content was observed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

A comparative study on the efficiencies of polyethylene compatibilizers by using theoretical methods

Functionalization of polyethylene chains by grafting of polar groups onto backbones is the most versatile way for preparing polyethylene based compatibilizers (PECs). In this work, a series of theoretical studies were performed to analyze the structure, adhesion and mixing behaviors of PECs. The effect of grafting different polar groups such as acrylic acid (AA), glycidyl methacrylate (GMA), maleic anhydride (MAH) and itaconic acid (IA) on the structure and cohesive properties of polyethylene chains were studied by Molecular Dynamics simulations. The mixing behavior of grafted polyethylenes with some commodity polymers such as polyetylene teraphthalate (PET), polyamide 6 (Nylon6), polyvinyl acetate (PVA) and polylactide (PLA) as well as with starch (ST) and starch acetate (STac) were investigated quantitatively by determining accurate interaction parameters using the modified Flory-Huggins Theory. We showed that the polar groups are the most reactive sites and they bind the chemically incompatible polymers by enabling the stronger interactions at the interfacial region.

Influences of blend compatibilizers on dynamic, mechanical, and morphological properties of dynamically cured maleated natural rubber and high-density polyethylene blends

Influences of various types and loading amounts of blend compatibilizers on properties of maleated natural rubber/high-density polyethylene thermoplastic vulcanizates (MNR/HDPE TPVs) were investigated. It was found that TPV with any of the three types of compatibilizer exhibited superior mechanical and dynamic properties to those of the TPV without compatibilizers. Furthermore, the phenolic modified polyethylene compatibilizers (i.e., PhSP-PE and PhHRJ-PE) showed a better compatibilizing effect than HDPE- g-MA. Comparing the three types of compatibilizer, the TPVs with PhHRJ-PE exhibited the best mechanical and dynamic properties and the smallest dispersed vulcanized rubber domains in the HDPE matrix. Five loading amounts of PhHRJ-PE were then studied. The PhHRJ-PE at a loading amount of 5 wt% of HDPE exhibited the best overall properties. The TPVs with lower and higher loading amounts of PhHRJ-PE exhibited inferior mechanical, dynamic and morphological properties.

Intercalated linear low density polyethylene (LLDPE)/clay nanocomposites prepared with oxidized polyethylene as a new type compatibilizer: Structural, mechanical and barrier properties

In this study, the use of low molecular weight oxidized polyethylenes (OxPE) with different molecular weight and acid number as a new type of compatibilizer in low density polyethylene (LLDPE)/org-clay nanocomposite preparation was examined. Nanocomposites having 5 phr (part per hundred) org-clay were prepared by melt processing. The effect of compatibilizer polarity and clay dispersion on the thermal, mechanical and barrier properties of the nanocomposites was investigated. It was observed that oxidized polyethylenes created a strong interfacial interaction between the clay layers and polymer phase based on the analysis of the linear viscoelastic behavior of the samples by small amplitude oscillatory rheometry. We showed that physical performance of the nanocomposites is not only affected by clay dispersion but also both melt viscosity and polarity of the oxidized polyethylene compatibilizers. It was found that oxygen permeability values of the nanocomposite samples prepared with the oxidized polyethylenes were lower than that of a sample prepared with conventional compatibilizer, maleic anhydride grafted polyethylene (PE- g-MA).

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

AbstractA 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

Polyethylene Organo-Clay Nanocomposites: The Role of the Interface Chemistry on the Extent of Clay Intercalation/Exfoliation

High density polyethylene (HDPE)/clay nanocomposites have been prepared using three different functionalized polyethylene compatibilizers: an ethylene/vinyl acetate copolymer, a polyethylene grafted with maleic anhydride functions and a (styrene-b-ethylene/butylene-b-styrene) block copolymer. The nanocomposites were prepared via two different routes: (1) the dispersion in HDPE of a masterbatch prepared from the compatibilizer and the clay or (2) the direct melt blending of the three components. For each compatibilizer, essentially intercalated nanocomposites were formed as determined by X-ray diffraction and transmission electron microscopy. With the ethylene/vinyl acetate copolymer, a significant delamination of the intercalated clay in thin stacks was observed. This dispersion of thin intercalated stacks within the polymer matrix allowed increasing significantly the stiffness and the flame resistance of the nanocomposite. A positive effect of shear rate and blending time has also been put into evidence, especially for the process based on the masterbatch preparation, improving both the formation of thin stacks of intercalated clay and the mechanical properties and the flame resistance of the formed nanocomposites.

Morphology and gas barrier properties of polyethylene‐based nanocomposites

AbstractNanocomposites were processed by melt blending two reference matrices, a metallocene polyethylene and a low density maleic anhydride‐grafted polyethylene with an organo‐modified montmorillonite. It was shown that the introduction of a maleated polyethylene compatibilizer was required to improve the clay nanoplatelet dispersion in the metallocene polyethylene‐based nanocomposites. Increasing the montmorillonite content led to a significant increase of the barrier properties. Interfacial agents such as oxidized paraffins were shown to be more effective to reduce the gas permeability than maleated polyethylene and the dependence of the gas transport properties was discussed not only as a function of the clay dispersion but also as a function of the clay/compatibilizer and compatibilizer/matrix interactions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 431–440, 2006

Dynamic mechanical behavior of high‐density polyethylene/ethylene vinyl acetate copolymer blends: The effects of the blend ratio, reactive compatibilization, and dynamic vulcanization

AbstractThe effects of the blend ratio, reactive compatibilization, and dynamic vulcanization on the dynamic mechanical properties of high‐density polyethylene (HDPE)/ethylene vinyl acetate (EVA) blends have been analyzed at different temperatures. The storage modulus of the blend decreases with an increase in the EVA content. The loss factor curve shows two peaks, corresponding to the transitions of HDPE and EVA, indicating the incompatibility of the blend system. Attempts have been made to correlate the observed viscoelastic properties of the blends with the blend morphology. Various composite models have been used to predict the dynamic mechanical data. The experimental values are close to those of the Halpin–Tsai model above 50 wt % EVA and close to those of the Coran model up to 50 wt % EVA in the blend. For the Takayanagi model, the theoretical value is in good agreement with the experimental value for a 70/30 HDPE/EVA blend. The area under the loss modulus/temperature curve (LA) has been analyzed with the integration method from the experimental curve and has been compared with that obtained from group contribution analysis. The LA values calculated with group contribution analysis are lower than those calculated with the integration method. The addition of a maleic‐modified polyethylene compatibilizer increases the storage modulus, loss modulus, and loss factor values of the system, and this is due to the finer dispersion of the EVA domains in the HDPE matrix upon compatibilization. For 70/30 and 50/50 blends, the addition of a maleic‐modified polyethylene compatibilizer shifts the relaxation temperature of both HDPE and EVA to a lower temperature, and this indicates increased interdiffusion of the two phases at the interface upon compatibilization. However, for a 30/70 HDPE/EVA blend, the addition of a compatibilizer does not change the relaxation temperature, and this may be due to the cocontinuous morphology of the blends. The dynamic vulcanization of the EVA phase with dicumyl peroxide results in an increase in both the storage and loss moduli of the blends. A significant increase in the relaxation temperature of EVA and a broadening of the relaxation peaks occur during dynamic vulcanization, and this indicates the increased interaction between the two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2083–2099, 2003

Rheological effects of the incorporation of chlorinated polyethylene compatibilizers in a HDPE/PVC blend

AbstractSmall‐amplitude oscillatory measurements, creep and recoil experiments, capillary extrusion flow and shrinkage measurements have been performed to elucidate the effect of block and random chlorinated polyethylene (CPE) on the rheological properties of a ternary high density polyethylene (HDPE)/ poly(vinyl chloride) (PVC)/CPE system. It is observed that the storage modulus, the complex viscosity and the steady stale viscosity at low shear rates decrease when a small amount of CPE is incorporated to 50/50 (wt.) HDPE/PVC binary blend. However, at high shear rates, in experiments performed in extrusion flow, the trend is reversed, and the incorporation of CPE to the binary blend increases viscosity. The high melt elasticity of HOPE is severely reduced when this polymer is mixed with PVC, but when CPE is included as a third component, elastic recovery is considerably increased. All these rheological results, which are independent of type (block or random) of CPE used, are explained considering the morphological changes produced by CPE and during extrusion flow.

Evaluation and characterization of vector fluids and peroxides in a process of in situ compatibilization of polyethylene and polystyrene

AbstractAn organic functional silane was found to be the most efficient among several vector fluids in reactive blend compatibilization of the polyethylene (PE) / polystyrene (PS) / peroxide / vector fluid system. This paper involves further analysis of this reactive blending system. Surface tension data was used to calculate spreading coefficients which were compared to the amount of PE‐PS copolymer formed during blending. A good correlation between a computed spreading coefficient and the degree of grafting of PS onto PE was found. The results suggest that the pattern of distribution of the vector fluid in PE / PS blends is the key factor leading to effective results. Furthermore, different peroxides were evaluated in PE / PS blends, in order to determine the dependence of PE / PS interfacial grafting reaction on the structure of the peroxide.

The relative role of coalescence and interfacial tension in controlling dispersed phase size reduction during the compatibilization of polyethylene terephthalate/polypropylene blends

The breaking thread and the sessile drop methods have been used to evaluate the interfacial tension between a polypropylene (PP) and a polyethylene-terephthalate (PET). An excellent correlation was found between the two. The breaking thread technique was then used to evaluate the interfacial tension of these blends at various levels of a styrene-ethylene butylene-styrene grafted with maleic anhydride (SEBS-g-MA) compatibilizer. In order to evaluate the relative roles of coalescence and interfacial tension in controlling dispersed phase size reduction during compatibilization, the morphology of PP/PET 1/99 and 10/90 blends compatibilized by a SEBS-g-MA were studied and compared. The samples were prepared in a Brabender mixer. For the 10/90 blend, the addition of the compatibilizer leads to a typical emulsification curve, and a decrease in dispersed phase size of 3.4 times is observed. For the 1/99 blend, a 1.7 times reduction in particle size is observed. In the latter case, this decrease can only be attributed to the decrease of the interfacial tension. It is evident from these results that the drop in particle size for the 10/90 PP/PET blend after compatibilization is almost equally due to diminished coalescence and interfacial tension reduction. These results were corroborated with the interfacial tension data in the presence of the copolymer. A direct relationship between the drop in dispersed phase size for the 1/99 PP/PET blend and the interfacial tension reduction was found for this predominantly shear mixing device. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2271–2280, 1997

The relative role of coalescence and interfacial tension in controlling dispersed phase size reduction during the compatibilization of polyethylene terephthalate/polypropylene blends

The breaking thread and the sessile drop methods have been used to evaluate the interfacial tension between a polypropylene ( PP ) and a polyethylene-terephthalate (PET). An excellent correlation was found between the two. The breaking thread technique was then used to evaluate the interfacial tension of these blends at various levels of a styrene-ethylene butylene-styrene grafted with maleic anhydride (SEBS-g-MA) compatibilizer. In order to evaluate the relative roles of coalescence and interfacial tension in controlling dispersed phase size reduction during compatibilization, the morphology of PP/PET 1/99 and 10/90 blends compatibilized by a SEBS-g-MA were studied and compared. The samples were prepared in a Brabender mixer. For the 10/90 blend, the addition of the compatibilizer leads to a typical emulsification curve, and a decrease in dispersed phase size of 3.4 times is observed. For the 1/99 blend, a 1.7 times reduction in particle size is observed. In the latter case, this decrease can only be attributed to the decrease of the interfacial tension. It is evident from these results that the drop in particle size for the 10/90 PP/PET blend after compatibilization is almost equally due to diminished coalescence and interfacial tension reduction. These results were corroborated with the interfacial tension data in the presence of the copolymer. A direct relationship between the drop in dispersed phase size for the 1/99 PP/PET blend and the interfacial tension reduction was found for this predominantly shear mixing device.