The effect of maleated compatibilizers on the structure and properties of EVOH/clay nanocomposites

The effect of compatibilizers on the blending torque, crystallization behavior, intercalation level, thermal stability and morphology of EVOH/treated clay systems was investigated. Maleic anhydride‐grafted ethylene vinyl acetate (EVA‐g‐MA) or maleic anhydride‐grafted linear low density polyethylene (LLDPE‐g‐MA) were used as compatibilizers of EVOH with clay, in various concentrations (1, 5 and 10 wt%). The blends were processed using Brabender Plastograph and characterized by XRD, SEM, DSC, DMTA and TGA. X‐ray diffraction shows advanced intercalation within the galleries when the compatibilizers were added. Unique results were obtained for the EVOH/clay/compatibilizer systems, owing to a high level of interaction developed in these systems, which plays a major role. Thermal analysis showed that with increasing compatibilizer content, lower crystallinity levels result, until at a certain content no crystallization has taken place. Significantly higher viscosity levels were obtained for the EVOH/clay blends compared to the neat polymer, as seen by a dramatic torque increase when processed in the Brabender machine. The DMTA spectra showed lower T_g values for the compatibilized nanocomposites compared to the neat EVOH and the uncompatibilized composites. Storage modulus was higher compared to the uncompatibilized EVOH/clay blend when EVA‐g‐MA compatibilizer was added (at all concentrations), and only at low contents of LLDPE‐g‐MA. TGA results show significant improvement of the blends thermal stability compared to the neat EVOH, and to the uncompatibilized blend, indicating an advanced intercalation.     

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     

Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO₃ composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO₃, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO₃ particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO₃ particles. The crystallization and mechanical properties of PP/nano‐CaCO₃ composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO₃ particles, favored the nucleation effect of nano‐CaCO₃, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO₃ composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO₃, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Physical properties and cure characteristics of natural rubber/nanoclay composites with two different compatibilizers

The effects of epoxidized natural rubber (ENR) and maleic anhydride‐grafted polybutadiene (PB‐g‐MA) as compatibilizers to rubber formulations with and without organo‐modified layered silicates are investigated. The physical properties and curing characteristics of composites are studied by moving die rheometer, rubber process analyzer, tensile, tear, and hardness testing. The state of organoclay intercalation was determined by X‐ray diffraction method. The addition of compatibilizers, especially ENR 50, results in further intercalation or exfoliation of the organoclay that increased the clay dispersion in the rubber matrix. ENR 50 with organo‐modified clay improves the physical properties and changes the curing profile. The addition of PB‐g‐MA without organoclay increases the tensile strength (σ_max) by increasing the stock viscosity of the rubber compound. Interestingly, simultaneous increase in hardness and σ_max is achieved in the presence of both compatibilizers, a characteristic that is difficult to achieve and sometimes required in rubber processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Development of blown film linear low-density polyethylene–clay nanocomposites: Part A: Manufacturing process and morphology

In this study, linear low-density polyethylene (LLDPE)/clay nanocomposites with different clay contents were prepared by melt intercalation using two different compatibilizers: maleic anhydride grafted styrene–ethylene–butylene–styrene and maleic anhydride grafted polyethylene (PE-g-MA). Melt intercalation was achieved by twin extrusion and nanocomposite films were produced by blown film extrusion. Effects of clay and compatibilizer fractions and type of compatibilizer on the structure, permeability, and the barrier properties of the nanocomposite films were investigated. PE-g-MA was shown to notably improve the dispersion of clay layers in the polyethylene matrix, and this was examined by atomic force microscopy and X-ray diffraction. The latter tests have also highlighted the importance of the screw configuration: the presence of mixing elements favors the dispersion and distribution of nanoclay. Moreover, differential scanning calorimetry results have shown no significant effect of the clay on the crystallinity of the composite while thermogravimetric analysis tests have demonstrated a decrease of onset and peak of decomposition temperatures. Finally, barrier properties toward water vapor transmission were measured. It was proven that not also clay, but the compatibilizer participated in decreasing the permeability of the film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48589.     

Preparation and properties of styrene–ethylene–butylene–styrene block copolymer/clay nanocomposites: I. Effect of clay content and compatibilizer types

BACKGROUND: Polymer/clay (silicate) systems exhibit great promise for industrial applications due to their ability to display synergistically advanced properties with relatively small amounts of clay loads. The effects of various compatibilizers on styrene–ethylene–butylene–styrene block copolymer (SEBS)/clay nanocomposites with various amounts of clay using a melt mixing process are investigated. RESULTS: SEBS/clay nanocomposites were prepared via melt mixing. Two types of maleated compatibilizers, styrene–ethylene–butylene–styrene block copolymer grafted maleic anhydride (SEBS‐g‐MA) and polypropylene grafted maleic anhydride (PP‐g‐MA), were incorporated to improve the dispersion of various amounts of commercial organoclay (denoted as 20A). Experimental samples were analyzed using X‐ray diffraction and transmission electron microscopy. Thermal stability was enhanced through the addition of clay with or without compatibilizers. The dynamic mechanical properties and rheological properties indicated enhanced interaction for the compatibilized nanocomposites. In particular, the PP‐g‐MA compatibilized system conferred higher tensile strength or Young's modulus than the SEBS‐g‐MA compatibilized system, although SEBS‐g‐MA seemed to further expand the interlayer spacing of the clay compared with PP‐g‐MA. CONCLUSION: These unusual results suggest that the matrix properties and compatibilizer types are crucial factors in attaining the best mechanical property performance at a specific clay content. Copyright © 2007 Society of Chemical Industry     

Effect of the molecular weight of maleated polypropylenes on the melt compounding of polypropylene/organoclay nanocomposites

Maleic anhydride grafted polypropylene (PP‐g‐MA) and organically modified clay composites were prepared in a plasticorder. PP‐g‐MAs, including Polybond PB3150, Polybond PB3200, Polybond PB3000, and Epolene E43, with a wide range of maleic anhydride (MA) concentrations and molecular weights were used. The structure was investigated with X‐ray diffraction (XRD) and transmission electron microscopy (TEM). PP‐g‐MA compatibilizers gave rise to similar degrees of dispersion beyond the weight ratio of 3/1, with the exception of E43, which had the highest MA content and the lowest molecular weight. The thermal instability and high melt index were responsible for the ineffective modification by E43. Furthermore, PP‐g‐MA with a lower molecular weight and a higher melt index had to be compounded at a lower mixing temperature to achieve a reasonable level of torque for clay dispersion. Polypropylene/organoclay nanocomposites were then modified with different levels of PP‐g‐MA compatibilizers with a twin‐screw extruder. The polypropylene/E43/clay system, as shown by XRD patterns and TEM observations, yielded the poorest clay dispersion of the compatibilizers under investigation. The curves of the relative complex viscosity also revealed a systematic trend with the extent of exfoliation and showed promise for quantifying the hybrid structure of the nanocomposites. The mechanical properties and thermal stability were determined by dynamical mechanical analysis and thermogravimetric analysis, respectively. Although PP‐g‐MA with a lower molecular weight led to better clay dispersion in the polypropylene nanocomposites, it caused deterioration in both the mechanical and thermal properties of the hybrid systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1667–1680, 2005     

Blends of recycled polycarbonate and acrylonitrile–butadiene–styrene: comparing the effect of reactive compatibilizers on mechanical and morphological properties

Blends of recycled polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) were prepared and some mechanical and morphological properties were investigated. To compatibilize these blends, ABS‐g‐(maleic anhydride) (ABS‐g‐MA) and (ethylene–vinyl acetate)‐g‐(maleic anhydride) (EVA‐g‐MA) with similar degree of grafting of 1.5% were used. To compare the effect of the type of compatibilizer on mechanical properties, blends were prepared using 3, 5 and 10 phr of each compatibilizer. A co‐rotating twin‐screw extruder was used for blending. The results showed that ABS‐g‐MA had no significant effect on the tensile strength of the blends while EVA‐g‐MA decreased the tensile strength, the maximum decrease being about 9.6% when using 10 phr of this compatibilizer. The results of notched Charpy impact strength tests showed that EVA‐g‐MA increased the impact strength of blends more than ABS‐g‐MA. The maximum value of this increase occurred when using 5 phr of each compatibilizer, it being about 54% for ABS‐g‐MA and 165% for EVA‐g‐MA. Scanning electron microscopy micrographs showed that the particle size of the dispersed phase was decreased in the continuous phase of PC by using the compatibilizers. Moreover, a blend without compatibilizer showed brittle behaviour while the blends containing compatibilizer showed ductile behaviour in fracture. © 2013 Society of Chemical Industry     

Extrusion of linear polypropylene–clay nanocomposite foams

This work presents new results on using organoclay with an appropriate polymeric compatibilizer as rheology‐modifying additives for extrusion foaming of a linear polypropylene (PP), which by itself does not display strain hardening in extensional flow of the melt. The uniaxial melt‐extensional viscosity behavior of several nanocomposites prepared with varying ratio of bound maleic anhydride to clay as well as varying compatibilizer molecular weight was investigated. A chemical‐blowing agent was used at a fixed concentration for foaming these nanocomposites in a single‐screw extruder. Among nanocomposites with similar levels of clay dispersion or intercalation, the ones that displayed significant strain hardening in the melt state along with slower crystallization led to extruded PP nanocomposite foams with smaller cell sizes and greater cell density by reducing cell coalescence. This was achieved with as little as 3 wt% organoclay and a high‐molecular weight PP‐g‐MA compatibilizer in linear PP. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Preparation of dynamically vulcanized thermoplastic elastomer nanocomposites based on LLDPE/reclaimed rubber

Dynamically vulcanized thermoplastic elastomers nanocomposites (TPV nanocomposites) based on linear low density polyethylene (LLDPE)/reclaimed rubber/organoclay were prepared via one‐step melt blending process. Maleic anhydride grafted polyethylene (PE‐g‐MA) was used as a compatibilizing agent. The effects of reclaimed rubber content (10, 30, and 50 wt %), nanoclay content (3, 5, and 7 wt %), and PE‐g‐MA on the microstructure, thermal behavior, mechanical properties, and rheological behavior of the nanocomposites were studied. The TPV nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy (SEM), differential scanning calorimeter, mechanical properties, and rheometry in small amplitude oscillatory shear. SEM photomicrographs of the etched samples showed that the elastomer particles were dispersed homogeneously throughout the polyethylene matrix and the size of rubber particles was reduced with introduction of the organoclay particles and compatibilizer. The effects of different nanoclay contents, different rubber contents, and compatibilizer on mechanical properties were investigated. Increasing the amount of nanoclay content and adding the compatibilizer result in an improvement of the tensile modulus of the TPV nanocomposite samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of Ionomeric Compatibilizer on Clay Dispersion in Polyethylene/Clay Nanocomposites

Summary: Linear low‐density polyethylene (LLDPE)/clay nanocomposites are obtained and studied by using a zinc‐neutralized carboxylate ionomer as a compatibilizer. LLDPE‐g‐MA is used as a reference compatibilizer. Two different clays, natural montmorillonite (Closite Na⁺) and a chemically modified clay Closite 20A have been used. Nanocomposites are prepared by melt blending in a twin‐screw extruder using two mixing methods: two‐step mixing and one‐step mixing. The relative influence of each compatibilizer is determined by wide‐angle X‐ray diffraction structural analysis and mechanical properties. The results are analyzed in terms of the effect of the compatibilizing agent and incorporation method in the clay dispersion, and the mechanical properties of the nanocomposites. Experimental results confirm that the film samples with ionomer show a good mechanical performance only slightly below that of the samples with maleic anhydride (MA). The two‐step mixing conditions result in better dispersion and intercalation for the nanofillers than one‐step mixing. The exfoliation of clay platelets leads to an improved thermal stability of the composite. The oxygen permeability of the clay nanocomposites, using ionomer as a compatibilizer, is decreased by the addition of the clay.

TEM image of a PE/4 wt.‐% Closite 20A nanocomposite formed using ionomer.     

Structure and oxygen‐barrier properties of (linear low‐density polyethylene/ethylene–vinyl alcohol copolymer)/linear low‐density polyethylene composite films prepared by microlayer coextrusion

Ethylene–vinyl alcohol copolymer (EVOH) and linear low‐density polyethylene (LLDPE) blends with 5% LLDPE grafted with 1% maleic anhydride (MAH; EVOH/LLDPE/LLDPE‐g‐MAH), created to increase the interfacial compatibility, were coextruded with pure LLDPE through the microlayer coextrusion technology. The phase morphology and gas‐barrier properties of the alternating‐layered (EVOH/LLDPE/LLDPE‐g‐MAH)/LLDPE composites were studied by scanning electron microscopy observation and oxygen permeation coefficient measurement. The experimental results show that the EVOH/LLDPE/LLDPE‐g‐MAH and LLDPE layers were parallel to each other, and the continuity of each layer was clearly evident. This structure greatly decreased the oxygen permeability coefficient compared to the pure LLDPE and the barrier percolation threshold because of the existence of the LLDPE/EVOH/LLDPE‐g‐MAH blend layers, and the LLDPE layers diluted the concentration of EVOH in the whole composites. In addition, the effects of the layer thickness ratio of the EVOH/LLDPE/LLDPE‐g‐MAH and LLDPE layers and the layer number on the barrier properties of the layered composites were investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42211.     

Properties of uncompatibilized and compatibilized poly(butylene terephthalate)–LLDPE blends

In this work, blends of poly(butylene terephthalate) (PBT) and linear low‐density polyethylene (LLDPE) were prepared. LLDPE was used as an impact modifier. Since the system was found to be incompatible, compatibilization was sought for by the addition of the following two types of functionalized polyethylene: ethylene vinylacetate copolymer (EVA) and maleic anhydride‐grafted EVA copolymer (EVA‐g‐MAH). The effects of the compatibilizers on the rheological and mechanical properties of the blends have been also quantitatively investigated. The impact strength of the PBT–LLDPE binary blends slightly increased at a lower concentration of LLDPE but increased remarkably above a concentration of 60 wt % of LLDPE. The morphology of the blends showed that the LLDPE particles had dispersed in the PBT matrix below 40 wt % of LLDPE, while, at 60 wt % of LLDPE, a co‐continuous morphology was obtained, which could explain the increase of the impact strength of the blend. Generally, the mechanical strength was decreased by adding LLDPE to PBT. Addition of EVA or EVA‐g‐MAH as a compatibilizer to PBT–LLDPE (70/30) blend considerably improved the impact strength of the blend without significantly sacrificing the tensile and the flexural strength. More improvement in those mechanical properties was observed in the case of the EVA‐g‐MAH system than for the EVA system. A larger viscosity increase was also observed in the case of the EVA‐g‐MAH than EVA. This may be due to interaction of the EVA‐g‐MAH with PBT. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 989–997, 1999     

Effects of compatibilizers and testing speeds on the mechanical properties of organophilic montmorillonite filled polyamide 6/polypropylene nanocomposites

In the present study, the fracture properties of different types of organophilic montmorillonite (OMMT) filled polyamide 6/polypropylene nanocomposites was investigated. Two types of compatibilizers, i.e., maleic anhydride grafted polypropylene (PP‐g‐MA) and maleic anhydride grafted styrene‐ethylene/butylene‐styrene (SEBS‐g‐MA) were used to compatibilize these systems. The tensile properties were studied through tensile test at two different testing speeds; 50 and 500 mm/min whereas the fracture properties were determined using single‐edge‐notch‐3 point‐bending (SEN‐3PB) specimens at three different testing speeds; 1, 100, and 500 mm/min. The presence of both PP‐g‐MA and SEBS‐g‐MA compatibilizers improved the tensile and fracture properties of nanocomposites due to the compatibilizing effect of both compatibilizers. SEBS‐g‐MA compatibilizer seemed to be more effective in improving the fracture toughness of nanocomposites than PP‐g‐MA especially at high testing speed. This was due to the elastomeric nature of SEBS‐g‐MA, which can provide a better toughening effect than the relatively harder PP‐g‐MA. POLYM. ENG. SCI., 50:1493–1504, 2010. © 2010 Society of Plastics Engineers     

Twin‐screw extrusion of polypropylene‐clay nanocomposites: Influence of masterbatch processing,screw rotation mode,and sequence

This work seeks to optimize the twin‐screw compounding of polymer‐clay nanocomposites (PCNs). Proportional amounts (3:1) of maleic anhydride functionalized polypropylene compatibilizer (PP‐g‐MA) and organically modified montmorillonite clay at clay loadings of 1, 3, and 5 wt% were melt‐blended with a polypropylene (PP) homopolymer using a Leistritz Micro 27 twin‐screw extruder. Three melt‐blending approaches were pursued: (1) a masterbatch of PP‐g‐MA and organoclay were blended in one pass followed by dilution with the PP resin in a second pass; (2) all three components were processed in a single pass; and (3) uncompatibilized PP and organoclay were processed twice. Both corotation and counterrotation operation were utilized to investigate the effect of screw rotation mode and sequence on organoclay exfoliation and dispersion. X‐ray diffraction was employed to characterize basal spacing; however, since rheology is known to be highly sensitive to mesoscale organoclay structure, it is an ideal tool to examine the relationship between the various processing methods and exfoliation and dispersion. A holistic analysis of rheological data demonstrates the efficacy of the masterbatch approach, particularly when compatibilizer and organoclay are blended in counterrotating mode followed by dilution with matrix polymer in corotating mode. POLYM. ENG. SCI., 47:898–911, 2007. © 2007 Society of Plastics Engineers     

Rice straw fiber reinforced high density polyethylene composite: Effect of coupled compatibilizating and toughening treatment

In this study, rice‐straw (RS) filled high density polyethylene (HDPE) composites were manufactured by extrusion and injection molding. Three compatibilizers, which are unfunctionalized ethylene/propylene copolymer (uEPR), maleic anhydride grafted EPR (EPR‐g‐MA) and PE‐g‐MA, and their combinations were introduced to strengthen fiber‐matrix interphase. The mechanical and morphological properties of composites were investigated. For single‐compatibilizer system, PE‐g‐MA or EPR‐g‐MA alone enhanced tensile, flexural, and impact strengths of resultant composites compared with HDPE/RS system without compatibilizers. Different toughening origins of individual compatibilizer were discussed based on composites' interphase morphologies and mechanical properties. For combined‐compatibilizers system, the PE‐g‐MA/EPR weight ratio is important for several properties of composites. The optimum ratio was considered as 2 : 1 and 1 : 1 for PE‐g‐MA/uEPR and PE‐g‐MA/EPR‐g‐MA modified composites, respectively. Also, composites modified by combined PE‐g‐MA/EPR‐g‐MA showed better impact strength than that modified by PE‐g‐MA alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Twin‐screw extrusion compounding of polypropylene/organoclay nanocomposites modified by maleated polypropylenes

Polypropylene/organoclay nanocomposites modified with different maleic anhydride grafted polypropylene (PPgMA) compatibilizers were compounded on a twin‐screw extruder. The effectiveness of the feeding sequence and compatibilizer type toward the dispersion of organoclay into PP matrix was critically studied. The composites prepared with side feed appeared to provide better dispersion and modulus improvement over that with hopper feed. The effect of PPgMA compatibilizers, including PB3150, PB3200, PB3000, and E43, with a wide range of maleic anhydride (MA) content and molecular weight was also examined. The structure was investigated with X‐ray diffraction and transmission electron microscopy. The relative complex viscosity curves also revealed a systematic trend with the extent of exfoliation and showed promise for quantifying the hybrid structure of the nanocomposites. Mechanical properties were determined by dynamical mechanical analysis and tensile and impact tests. Maleated polypropylene with low‐melt flow index and moderate MA content enhanced clay dispersion and resulted in significant improvement in tensile modulus of the nanocomposites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 100–112, 2004     

Interfacially compatibilized poly(lactic acid) and poly(lactic acid)/polycaprolactone/organoclay nanocomposites with improved biodegradability and barrier properties: Effects of the compatibilizer structural parameters and feeding route

Nanocomposites with enhanced biodegradability and reduced oxygen permeability were fabricated via melt hybridization of organomodified clay and poly (lactic acid) (PLA) as well as a PLA/polycaprolactone (PCL) blend. The nanocomposite microstructure was engineered via interfacial compatibilization with maleated polypropylene (PP‐g‐MA). Effects of the compatibilizer structural parameters and feeding route on the dispersion state of the nanolayers and their partitioning between the PLA and PCL phases were evaluated with X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Although highly functionalized PP‐g‐MA with a low molecular weight was shown to be much more effective in the intercalation of PLA and the PLA/PCL blend into the clay gallery spaces, composite samples compatibilized by high‐molecular‐weight PP‐g‐MA with a lower degree of maleation exhibited lower oxygen permeability as well as a higher rate of biodegradation, which indicated the accelerating role of the dispersed nanolayers and their interfaces in the enzymatic degradation of PLA and PLA/PCL matrices. This evidenced a correlation between the nanocomposite structure and rate of biodegradation. The size of the PCL droplets in the PLA matrix was reduced by nanoclay incorporation, and this revealed that the nanolayers were preferentially wetted by PCL in the blend. However, PCL appeared as fine and elongated particles in the microstructure of the PLA/PCL/organoclay hybrids compatibilized by higher molecular weight and less functionalized PP‐g‐MA. All the PLA/organoclay and PLA/PCL/organoclay hybrids compatibilized with high‐molecular‐weight PP‐g‐MA displayed a higher dynamic melt viscosity with more pseudo solid‐like melt rheological responses, and this indicated the formation of a strong network structure by the dispersed clay layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influences of compatibilizers on rheology and mechanical properties of propylene random copolymer/styrene‐ethylene‐butylene‐styrene block copolymer/organic‐montmorillonite nanocomposites

Propylene random copolymer (PPR)/styrene‐ethylene‐butylene‐styrene block copolymer (SEBS)/compatibilizer/organic‐montmorillonite (OMMT) quaternary nanocomposites and PPR/compatibilizer/OMMT ternary nanocomposites were prepared via two‐stage melt blending and influences of compatibilizers, maleic anhydride (MA) grafted styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA), poly(octene‐co‐ethylene) (POE‐g‐MA), or propylene block copolymers (PPB‐g‐MA), on rheology and mechanical properties of the nanocomposites were investigated. The results of X‐ray diffraction measurement and transmission electron microscopy observation showed that OMMT layers were mainly intercalated in the nanocomposites except for the mainly exfoliated structure in the quaternary nanocomposites using POE‐g‐MA as compatibilizer. The nanocomposites exhibited pseudo‐solid like viscoelasticity in low frequencies and shear‐thinning in high shear rates. As far as OMMT dispersion was concerned, POE‐g‐MA was superior to SEBS‐g‐MA and PPB‐g‐MA, which gives rise to the highest viscosities in both the ternary and quaternary nanocomposites. The quaternary nanocomposites containing POE‐g‐MA were endowed with balanced toughness and rigidity. It was suggested that a suitable combination of compatibilizer and SEBS was an essentially important factor for adjusting the OMMT dispersion and distribution, the rheological and mechanical performances of the nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of functionalized polyethylenes on clay dispersion in high density polyethylene nanocomposites

The compatibilization effects provided by maleic anhydride (MA), itaconic acid (IAc), itaconic anhydride (IA), and 2-[2-(dimethylamine)-ethoxy]ethanol (DMAE) functionalized polyethylenes for forming high density polyethylene (HDPE)-based nanocomposites were studied and compared. IAc and IA were grafted into HDPE by melt mixing to obtain functionalized polyethylenes (HDPEgIAc and HDPEgIA) and amino alcohol functionalized polyethylene was prepared by reaction of commercial HDPEgMA with DMAE in the melt to form polyethylene-grafted dimethyl-amine-ethoxy-ethanol (PEgDMAE). Nanocomposites were prepared by melt processing using a twin screw extruder by blending polyethylene and these compatibilizers with a quaternary ammonium surfactant-modified montmorillonite clay (Nanomer I28E). FTIR characterization confirmed the formation of these compatibilizers and confirmed the reaction between HDPEgMA and the amino alcohol. All the compatibilized nanocomposites had better clay exfoliation compared to the uncompatibilized HDPE nanocomposites. Barrier properties, X-ray diffraction and transmission electron microscopy results showed the following order of their performance as a compatibilizer: PEgDMAE > HDPEgAI > HDPEgAcI > HDPEgMA. This behavior was attributed to the specific interactions between the anionic surface of the clay and the functionality of the compatibilizer. Samples with higher clay content showed poorer clay dispersion or intercalation which was attributed to possible clay saturation when the van der Waals attractive interactions between the clay layers become dominant when the distance between them was small enough at a certain concentration of clay. A noticeable reduction in the degree of crystallinity with the incorporation of nanoclay was observed by thermal analysis whereas the melting temperature did not change noticeably.