Compatibilizer Level Research Articles

Development of linear low‐density polyethylene nanocomposite films for storage of sugarcane juice

AbstractSugarcane juice is a cheap and popular product in the beverage industry, with colors varying from light gray to dark green containing abundant amounts of polyphenolic compounds, ascorbic acid, minerals, and pigments. With ample sucrose content, sugarcane juice has evolved as the primary raw material for manufacturing 70% of the world's sugar content. Despite having high nutritional value, the shelf life of juice is a severe concern owing to the onset of microbial activities, which speeds up the fermentation process immediately after the extraction, which calls for appropriate packaging for delaying the qualitative degradation. For this purpose, the physicochemical properties, microbial stability, and color properties of “Mandya” variety sugarcane juice was ascertained upon storage in developed nanocomposite films made of linear low‐density polyethylene (LLDPE) by varying the levels of compatibilizer, nanoclay, and thickness. Upon evaluating the results, it was observed that the critical physicochemical attributes, namely, total soluble solids (TSS), pH, total sugars, and overall acceptability, were found to decrease with an increase in the level of nanoclay and compatibilizer and decrease in film thickness. Zero plate counts were observed till day 15 of storage, and a gradual increase was noticed in the further days. Correspondingly, an increase in the overall color difference with the progression of storage also occurred. It was concluded from the analysis that film of 100 μm thickness prepared from a combination of 93% LLDPE, 5% compatibilizer, and 2% nanoclay gave superior shelf life, minimum change in quality parameters, and least microbial population in sugarcane juice.Practical ApplicationFruit juice industries are interested in using packaging films with high tensile strength and low permeability instead of expensive glass bottles. Nanocomposite technology could be an effective tool for developing high‐barrier packaging material. LLDPE has many applications for developing both rigid form and flexible films. Most research studies on sugarcane juice preservation are confined to bottling, and there is a scarcity of information on the storage of sugarcane juice in pouches. In this context, the goal of the present study is to develop a cost‐effective packaging technology for the storage of sugarcane juice.

Toughening and thermal characteristics of plasticized polylactide and poly(butylene adipate-co-terephthalate) blend films: Influence of compatibilization

Bio-based polylactide (PLA) derived from fermented corn starch was blended with poly(butylene adipate-co-terephthalate) (PBAT) and triethyl citrate (TEC) plasticizer using a twin screw extruder. PLA-grafted-maleic anhydride (PLA-g-MA) synthesized via reactive maleation and toluene diisocyanate (TDI) were used as compatibilizers for these blends. Improvements in the toughness, phase morphology and thermal behavior of the PLA/PBAT/TEC (PBT) blend films were evaluated in terms of compatibilization effect. The compatibilized PBT blends showed noticeably superior tensile strength, elongation, and tensile-impact toughness compared with uncompatibilized ones due to the greater compatibility of PLA and PBAT phases. Well dispersed PBAT particles and many elongated fibrils were observed on the fracture surface of the film after compatibilization. Both TDI and PLA-g-MA were effective compatibilizers for the blend at an appropriate level. The addition of PLA-g-MA to the plasticized blends not only significantly enhanced mechanical properties and phase adhesion, but also accelerated cold crystallization and formed crystal perfection, a result of improvements in chain mobility and packing efficiency. Differential scanning calorimetry (DSC) results revealed changes in Tg and melting behavior of the blends from influences of compatibilization. The different types and levels of compatibilizer affected the thermal stability of the PLA phase but did not affect char remaining.

Influence of compatibilizer and multifunctional additive loadings on flame retardation, plasticization, and impact modification of polylactide and poly(butylene adipate‐co‐terephthalate) biodegradable blends

The poor compatibility and flame retardation of polylactide (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) blends seriously limit their applications. This study focused on the mechanical properties and flame retardancy of a PLA/PBAT blend under the influence of different levels of compatibilizer and multifunctional additives (MFA). PLA and PBAT were successfully compatibilized via reactive blending in a twin‐screw extruder. The flame retardation, flexibility, and impact toughness of the compatibilized blend were improved by the presence of tricresyl phosphate (TCP) and triethyl citrate (TEC). Separately and in combination, the two additives played crucial roles in flame retardant effectiveness, plasticization, and impact modification. The compatibilized blend displayed a UL‐94 V‐0 rating and exhibited a high limiting oxygen index (LOI). A slight reduction in thermal stability was exhibited when 20 phr TCP was incorporated into the blend. During combustion, an integrated char layer formed on the compatibilized blend surface and retarded flammability. The combination of TCP and TEC not only significantly improved dripping behavior and flame‐retardant properties of the compatibilized blend but also cooperatively enhanced the elongation at break and impact strength without impacting tensile strength, Young's modulus, LOI value, and thermal stability. The failure behavior of the blend changed from brittle to ductile, as evidenced by SEM, which revealed elongated fibrils after tension. These characteristics were associated with the presence of the MFAs and the improved interfacial adhesion between PLA and PBAT. As a result, flame retardation, flexibility, and impact resistance were enhanced. These improvements permit the wider application of PLA, especially in the electronic and automotive fields.Highlights Compatibilized PLA/PBAT blend achieved the V‐0 rating and had a high LOI. Both TCP and TEC could be used as multifunctional additives (MFAs) in the compatibilized blend. Combination of MFAs synergistically enhanced elongation at break and impact strength without impacting other properties of the blends. These improvements permit the wider application of PLA, especially in the electronic and automotive fields.

Investigation on the Thermal Degradation Kinetics of Polypropylene/Organically Modified Montmorillonite Nanocomposites with Different Levels of Compatibilizer

AbstractPolypropylene/organically modified montmorillonite (OMMT) nanocomposites are prepared with different levels of compatibilizer (maleic anhydride functionalized polypropylene) and OMMT. A specially designed polymer nanocomposite injection molding compounder with a hyperbolic nozzle is used to prepare the nanocomposites. The thermal kinetic parameters, the activation energy, pre‐exponential factor, and the reaction model are estimated using isoconversional methods. The activation energy of virgin polypropylene is slightly higher than the polypropylene/OMMT nanocomposites. However, the presence of the compatibilizer is the vital reason for the lower activation energy in the polypropylene/OMMT nanocomposites. The reaction model explains the complexity of the reaction in the presence of OMMT and its influence on the accelerated charring in the later stages of degradation. The optimum working temperature of the prepared polypropylene/clay nanocomposites is significantly higher thus proving that OMMT improves the thermal stability of the nanocomposites. The polypropylene with 5% OMMT and 10% compatibilizer in its weight proportion has the optimum working temperature of 198 °C for 20 000 h before losing its integrity.

Rheology, mechanical properties and thermal degradation kinetics of polypropylene (PP) and polylactic acid (PLA) blends

The blending of immiscible polymers and their compatibilization leads to materials with tailor-made properties suitable for wide range of applications. Polypropylene (PP) and polylactic acid (PLA) were blended in different weight ratios and the optimized blend was compatibilized with maleic anhydride grafted PP (MA-g-PP) in varying amounts from 0 to 5 wt%. Rheological studies performed using a capillary rheometer showed the pseudo plastic behavior of the blends and from the shear viscosity data, it was observed that 3 wt% of the compatibilizer effectively compatibilized the selected blend. Mechanical properties further confirmed this finding. Thermogravimetric analysis revealed a two-stage degradation mechanism for the blends, corresponding to each component in the blend system. The apparent activation energy (Ea) values for the thermal degradation were calculated using Kissinger method, Horowitz and Metzger method, Kissinger–Akahira–Sunose equation, Friedman model and Ozawa–Flynn and Wall method. Coats-Redfern method was used to elucidate the mechanism of thermal degradation of the chosen blend system. The Ea values for PLA component of the blend increased with increase in compatibilizer addition up to 3 wt% and then decreased, whereas, it decreased for PP fraction up to a compatibilizer level of 3 wt% and then increased.

Study of Thermal Properties of Mixed (PP/EPR)/ABS with Five Model Compatibilizers

The influences of incorporating compatibilizers E-EA-MAH, E-MA-GMA, E-AM, SEBS KRATON G, or PP-g-MAH on the thermal properties of mixed (polypropylene/ethylene propylene rubber)/acrylonitrile butadiene styrene (PP/EPR)/ABS have been investigated. DSC investigations have revealed that the incorporation of 5% of ABS in the copolymer (PP/EPR) does not fundamentally affect the thermal properties of the basic copolymer; additionally, the addition of 1.5% of each of the compatibilizers in the basic mixture does not significantly alter the crystallization temperature values and the melting of the -P- sequences. There is a variation of melting enthalpy values of the -P- sequences of 18.23% using SEBS KRATON G and of 10.38% using E-AM-GMA. When the rate of each of the compatibilizers increases to 5%, overall crystallization enthalpies of -P- sequences are almost kept unchanged, except for the case of using the compatibilizer E-AM-GMA with a variation of 8.42%. There is a minor variation of the melting enthalpy of -P- sequences with higher levels of compatibilizer. The incorporation of 5% ABS copolymer in the PP/EPR does not significantly alter the thermal properties of the basic structure of (PP/EPR)/ABS.

Phase morphology and interfacial characteristics of polycarbonate/acrylonitrile‐ethylene‐propylene‐diene‐styrene blends compatibilized by styrene‐maleic anhydride copolymers

ABSTRACTBlends of polycarbonate (PC) and acrylonitrile‐ethylene‐propylene‐diene‐styrene (AES) were reactive compatibilized by styrene‐maleic anhydride copolymers (SMA). The changes in phase morphology and interfacial characteristics of the blends as a function of maleic anhydride content of SMA and the concentration of compatibilizer have been systematic studied. The occurrence of reaction between the terminal hydroxyl groups of PC and the maleic anhydride (MA) of compatibilizer was confirmed by fourier transform infrared (FTIR) spectroscopy. A glass transition temperature (Tg) with an intermediate value between Tg(AES) and Tg(PC) was found on differential scanning calorimeter (DSC) curves of PC/AES blends compatibilized with SMA contains high levels of MA. Furthermore, at lower compatibilizer content, increase of the compatibilizer level in blends result in decreasing gap between two Tgs corresponding to the constituent polymers. Small angle X‐ray scattering (SAXS) test results indicated that compatibilizer concentration for the minimum of blend interface layer's thickness was exactly the same as it was when compatibilized PC/AES blend exhibited optimal compatibility in DSC test. The observed morphological changes were consistent well with the DSC and SAXS test results. A new mechanism of interfacial structural development was proposed to explain unusual phenomena of SMA compatibilized PC/AES blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42103.

Use of maleic anhydride compatibilization to improve toughness and other properties of polylactide blended with thermoplastic elastomers

Polylactide (PLA) being a very brittle biopolymer could be toughened by blending with thermoplastic elastomers such as thermoplastic polyurethane elastomer (TPU) and thermoplastic polyester elastomer (TPE); unfortunately, these blends are immiscible forming round domains in the PLA matrix. Therefore, the purpose of this study was to investigate the effects of using maleic anhydride (MA) compatibilization on the toughness and other properties of PLA blended with TPU and TPE. MA grafting on the PLA backbone (PLA-g-MA) was prepared separately by reactive extrusion and added during melt blending of PLA/thermoplastic elastomers. IR spectroscopy revealed that MA graft might interact with the functional groups present in the hard segments of TPU and TPE domains via primary chemical reactions, so that higher level of compatibilization could be obtained. SEM studies indicated that PLA-g-MA compatibilization also decreased the size of elastomeric domains leading to higher level of surface area for more interfacial interactions. Toughness tests revealed that Charpy impact toughness and fracture toughness (KIC and GIC) of inherently brittle PLA increased enormously when the blends were compatibilized with PLA-g-MA. For instance, GIC fracture toughness of PLA increased as much as 166%. It was also observed that PLA-g-MA compatibilization resulted in no detrimental effects on the other mechanical and thermal properties of PLA blends. Copyright © 2014 John Wiley & Sons, Ltd.

Foaming behavior of microcellular thermoplastic olefin blends

The influence of reactive compatibilization on the foaming behavior of thermoplastic olefin blends of polypropylene and a metallocene-catalyzed ethylene octene copolymer was investigated. A batch setup was used to foam the samples using carbon dioxide as blowing agent. Solubility measurements were performed to determine the relative amount of gas concentration in the pressurized polymers before foaming. A microscopic method based on the back-scattered electron imaging technique was used to determine the respective locations of the bubbles and the dispersed elastomeric domains in the polypropylene matrix. It was shown that the bubbles are preferentially formed in the dispersed elastomeric domains. A clear relationship was established between the microstructure of the blends prepared with different levels of compatibilizer and the final cellular morphology of the microcellular thermoplastic olefin foams. The initial morphology of the blends was also altered by quiescent coarsening as well as shear-induced phase coalescence, and the impact of the morphological transitions on the cellular structure of the resulting foams was investigated. Dynamic shear and transient measurements of elongation were performed to characterize the viscoelastic behavior of the thermoplastic olefins. It was shown that the addition of a compatibilizer resulted in enhanced viscoelastic properties at low frequencies as well as increased levels of strain hardening, especially at low strain rates. The reactive compatibilization could significantly improve the melt foamability through control of the blend microstructure as well as enhancement of the melt rheological properties.

Rheology‐morphology correlation in PET/PP blends: Influence of type of compatibilizer

Rheological and morphological properties of melt processed poly(ethylene terephthalate) (PET)/polypropylene (PP) blends are presented. Two types of compatibilizer namely, PP‐g‐MA <MA= maleic anhydtide> and Elvaloy PTW, an n‐butyl acrylate glycidyl methacrylate ethylene terpolymers, were incorporated at different levels to the PET/PP blend system. Scanning electron microscopy revealed that the dispersed particle sizes were smaller in PET‐rich blends than PP‐rich blends. With increasing compatibilizer level, the refinement of morphology was observed in both the systems. However, the blends compatibilized with PTW showed a more refined (smaller) particle size, and at high PTW content (10 wt%), the morphology changed towards monophasic. The significant changes in morphology were attributed to the highly reactive nature of PTW. Investigation of rheological properties revealed that the viscosity of the PET/PP blends followed typical trends based on mixing rule, which calculates the properties of blends based on a linear average. Incorporation of PP‐g‐MA into the blends resulted in a negative deviation in the viscosity of the system with respect to that of the neat blend. With increasing PP‐g‐MA level, the deviation became more pronounced. Although incorporation of the compatibilizer into the PET/PP blends refined the morphology, it led to a drastic drop of viscosity, which could be attributed to inherently lower molecular weight of the compatibilizer. In the case of the blends compatibilized by PTW, a strong positive deviation in rheological properties was observed that confirmed the stronger interaction between the blend components due to reactive compatibilization process, which led to the more refined morphology in this series of blends. J. VINYL ADDIT. TECHNOL., 19:25–30, 2013. © 2013 Society of Plastics Engineers

Influence of processing variables on the mechanical behavior of HDPE/clay nanocomposites

Nanocomposites were processed using the technique of melt intercalation, starting from a concentrated polar compatibilizer/organoclay (PE-g-MA/organoclay) prepared in an internal mixer. The concentrate was incorporated into the matrix of HDPE by two methods: I) counter-rotating twin-screw extruder and II) co-rotating twin-screw extruder, using two screw profiles (ROS and 2KB90). After extrusion, the specimens of the extruded composites were injection molded. The X-ray diffraction (XRD) technique was used to analyze the degree of expansion of the prepared clays. To analyze the degree of exfoliation of obtained nanocomposites, XRD and TEM (transmission electron microscopy) were used. The influence of processing variables on mechanical properties was studied through the behavior of the modulus and tensile strength of nanocomposite systems. By XRD and TEM, it was seen that the clay was well dispersed in the matrix and the presence of intercalated and partially exfoliated hybrid structure for nanocomposites was observed when the systems were prepared in counter-rotating twin-screw extruder. A similar behavior was observed in the use of screws (2KB90 or ROS) of the nanocomposites, with a reduction in modulus and tensile strength. Although the mixing process by extruding be the most common industrial practice, and also it is the preferred strategy for the preparation of polymer nanocomposites, much of the literature was directed to the study of chemical modification of clay, type and level of compatibilizer, in order to maximize the compatibility between clay and the polymeric matrix. On the other hand, studies about the role of the processing and configurations of screws are relatively scarce. The main motivation of this work was to expand and to contribute to spread a better understanding of the effects of processing to obtain polymer nanocomposites.

Grafting of maleic anhydride onto polypropylene, in the presence and absence of styrene, for compatibilization of poly(ethylene terephthalate)/(ethylene–propylene) blends

AbstractGrafting of polypropylene (PP) by reactive processing in the presence and absence of styrene (ST) was performed to assess the effect of each one of the copolymers obtained in the compatibilization of poly(ethylene terephthalate) and (propylene–ethylene) copolymer blends, PET/EP copolymer (80/20). Grafting reactions of maleic anhydride and ST onto PP were conducted according to an experimental design where the concentrations of maleic anhydride and ST were varied. The amount of reacted maleic anhydride and the extent of degradation in PP were determined by means of Fourier‐transformed infrared spectroscopy and melt‐flow index, respectively. The PET/EP copolymer blends were obtained in a co‐rotating twin‐screw extruder. The effect of grafted copolymer type, PP‐g‐MA (PP grafted with maleic anhydride) or PP‐g‐MAST (PP grafted with maleic anhydride and styrene) in the compatibilization of PET/EP copolymer blends was assessed through mechanical (tensile test), morphological (scanning electron microscopy), and rheological properties. The presence of ST in the grafting reaction of maleic anhydride onto PP showed to significantly increase the amount of reacted maleic anhydride and reduce PP degradation. However, increasing ST concentration in the reaction mass affected the investigated variables only when maleic anhydride concentration was at its lowest level. Results of the PET/EP blends showed that both graft copolymers improved polymer interface adhesion, however, PP‐g‐MAST showed improved performance for the same level of compatibilizer used. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Rheological and morphological properties of reactively compatibilized thermoplastic olefin (TPO) blends

Thermoplastic olefin blends of polypropylene (PP) and ethylene octene copolymers (EC) were reactively compatibilized by means of functional reactive compounds capable of forming copolymers at the interface. For this purpose, amine functional groups were first incorporated into a PP in a solution reaction. The aminated PP was then used as the reactive compatibilizer during melt mixing. Linear viscoelastic measurements showed that the compatibilized blends feature the characteristics of materials in the sol–gel transition, with a power-law behavior for the dynamic moduli at low frequencies. The gel-like behavior was more pronounced in the blend with a high level of compatibilizer (10 wt. %). At high frequencies, however, the dynamic properties of all the blends investigated (compatibilized and noncompatibilized) were identical, suggesting that the bulk properties of the blends were not changed by the reactive compatibilization. The presence of a network structure was also confirmed by microscopic observations. A large transient viscosity with a significant and broad overshoot was observed for the compatibilized blends at low shear rate. In addition, the stress of the compatibilized blends relaxed over a much longer time as compared to the noncompatibilized system. The ability of different linear viscoelastic models in predicting the linear viscoelastic behavior of the compatibilized blends was also examined.

Study of the effective parameters on mechanical and electrical properties of carbon black filled PP/PA6 microfibrillar composites

In this study the electrical and mechanical properties of microfibrillar polypropylene (PP)/polyamide6 (PA6) blend filled with super conductive carbon black (CB) have been investigated. In situ microfibrillar PP/PA6 composites filled with CB are produced using a single screw extruder equipped with a spinneret. Glycidyl methacrylate (GMA) grafted polypropylene (PP-g-GMA) is used as the compatibilizer. To investigate the effects of extensional flow on the microstructure, electrical and mechanical properties, three adaptors with various convergence angles were designed, prepared and applied between the extruder and the spinneret. To optimize the effects of processing and material parameters on the electrical and mechanical properties, the Taguchi method of experimental design is used. Material and processing factors which are studied include: concentration of PA6, compatibilizer level, CB concentration, drawing speed of melt spinning line, adaptor angle, order of mixing and temperature profile along the extruder. The results show an increase in DC conductivity of up to 10 11 times in comparison with pure PA6, by increasing the concentration of CB, drawing speed, adaptor angle and optimizing other parameters. By optimizing processing and material factors studied here, strength of microfibrillar structured composites is increased of up to 80% in comparison to pure PP.

Effects of olefin‐based compatibilizers on the morphology, thermal and mechanical properties of ABS/polyamide‐6 blends

AbstractIn this study, commercially available epoxidized and maleated olefinic copolymers, EMA‐GMA (ethylene‐methyl acrylate‐glycidyl methacrylate) and EnBACO‐MAH (ethylene‐n butyl acrylate‐carbon monoxide‐maleic anhydride), were used at 0, 5, and 10% by weight to compatibilize the blend composed of ABS (acrylonitrile‐butadiene‐styrene) terpolymer and PA6 (polyamide 6). Compatibilizing performance of these two olefinic polymers was investigated from blend morphologies, thermal and mechanical properties as a function of blend composition, and compatibilizer loading level. Scanning electron microscopy (SEM) studies showed that incorporation of compatibilizer resulted in a fine morphology with reduced dispersed particle diameter at the presence of 5% compatibilizer. The crystallization behavior of PA6 phase in the blends was explored for selected blend compositions by differential scanning calorimetry (DSC). At high compatibilizer level a decrease in the degree of crystallization was observed. In 10% compatibilizer containing blends, formation of γ‐crystals was observed contrary to other compatibilizer compositions. The behavior of the compatibilized blend system in tensile testing showed the negative effect of using excess compatibilizer. Different trends in yield strengths and strain at break values were observed depending on compatibilizer type, loading level, and blend composition. With 5% EnBACO‐MAH, the blend toughness was observed to be the highest at room temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 926–935, 2007

Compatibilization of PS and PA6 Blends by Means of Poly(oxyalkylene)amine Modified Styrene-Maleic Anhydride Copolymer

The compatibilization effect of SMA-co-M2070-co-DAP comb-like copolymers, SMMD, on immiscible blends of polystyrene (PS) and polyamide-6 (PA6) is examined in terms of phase structure, thermal behavior, dynamic mechanical analysis, and mechanical properties. A series of SMMD copolymers are synthesized and confirmed by the FT-IR analysis. These compatibilizers have different amphiphilic properties depending on the content of hydrophilic poly(oxyethylene) segments (M2070) and the molar ratio of MA/amine. The morphologies of PS/PA6, affected by the increasing amount of SMMD compatibilizer, show a more regular and finer dispersion. The sizes of dispersed particles have no marked changes over the saturation level of compatibilizer. The glass transition temperatures of the blends are between that of PS and PA6, while the added SMMD copolymer is mainly located at the interface. Using these SMMD copolymers, the compatibilized blends show some improvements in mechanical properties, including Izod impact strength and flexural properties. The graft poly(oxyethylene) and amide functionalities in SMMD structures in forming hydrogen bonding with PA6 and, the polystyrene backbone in π–π interaction with PS facilitate the compatibilizing effect.

Interfacial modification of high density polyethylene/glass fiber reinforced and non reinforced polyamide 66 blends

AbstractHigh density polyethylene (HDPE) and polyamide (PA66) are well known to be incompatible. An ionomer (Surlyn) was added as a compatibilizer to HDPE and glass fiber reinforced (HDPE/GFRPA66) and non‐reinforced (HDPE/PA66) blends. Two compositions were considered: 25/75 wt % and 75/25 wt %, with an emphasis on the former formulation. The influence of the compatibilizer on the rheology, thermal properties, and the morphology, as well as mechanical properties of the blends, was investigated using melt flow index measurements, DSC, scanning electron microscopy (SEM), and impact strength. The ionomer was found to be more effective as a compatibilizer with HDPE as a minor phase compared to the case when HDPE becomes the major phase. The results indicated that the interfacial properties of the blends were improved, with a maximum appearing at a critical concentration of the ionomer (7.5 vol %). At this level of compatibilization, SEM analysis revealed better interfacial adhesion and a finer dispersion. MFI results revealed a probable reaction between the amine groups of PA66 and the acid functions of the ionomer. The mechanical properties support the above results and showed that the addition of 25 wt % HDPE did not affect the properties of PA66 much and the presence of glass fiber did not hinder the effect of the compatibilizer. Only 20% decrease in notched Izod impact strength of the blends is observed at 7.5 vol % ionomer content, suggesting that the addition of 25 wt % of HDPE to PA66 is not detrimental at this level of compatibilization. The emulsification curve was established and revealed that, in terms of impact properties, the finer the particle size, the higher the impact strength corresponding to 7.5 vol % ionomer content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1748–1760, 2005

Deformation and fracture behavior of polypropylene–ethylene vinyl alcohol blends compatibilized with ionomer Zn2+

AbstractThis work investigated the deformation and fracture behavior of polypropylene–ethylene vinyl alcohol (PP/EVOH) blends compatibilized with ionomer Zn2+. Uniaxial tensile tests and quasistatic fracture experiments were performed for neat PP and for 10 and 20 wt % EVOH blends with different ionomer contents. The addition of EVOH copolymer to PP led to an increase in the Young's modulus whereas the yield strength was decreased with the EVOH content as a consequence of the higher stiffness of EVOH and the poor interfacial adhesion between PP and EVOH, respectively. Furthermore, the incorporation of EVOH into PP promoted stable crack growth. Neat PP displayed nonlinear load‐displacement behavior with some amount of slow crack growth preceding unstable brittle fracture, whereas most PP/EVOH blends exhibited “pseudostable” fracture characterized by slow crack growth that could not be externally controlled. All blends exhibited lower resistance to crack initiation than PP but the fracture propagation resistance was significantly improved. For 10 wt % EVOH blends, the resistance to crack initiation was roughly constant with the ionomer content up to 5%, then it increased with the further addition of compatibilizer. Conversely, for 20 wt % EVOH blends, the resistance to crack initiation appeared to be independent of the ionomer content. The better resistance to crack initiation exhibited by the 10 wt % EVOH blends could be attributed to a higher level of compatibilization in these blends. By contrast, 20 wt % EVOH blends with ≤2% ionomer content showed completely stable crack growth. In addition, J–R curves and valid plane strain fracture toughness values for these blends could also be determined. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1271–1279, 2005

Compatibilization of high‐impact polystyrene/high‐density polyethylene blends by styrene/ethylene–butylene/styrene block copolymer

AbstractCompatibilization of polymer blends of high‐impact polystyrene (HIPS) and high‐density polyethylene (HDPE) blend by styrene/ethylene–butylene/styrene (SEBS) was elucidated. Polymer blends containing many ratios of HIPS and HDPE with various concentrations of SEBS were prepared. The Izod impact strength and elongation at break of the blends increased with increases in SEBS content. They increased markedly when the HDPE content was higher than 50 wt %. Tensile strength of blends increased when the SEBS concentration was not higher than 5 pphr. Whenever the SEBS loading was higher than 5 pphr, the tensile strength decreased and a greater decrease was found in blends in which the HDPE concentration was more than 50 wt %. The log additivity rule model was applied to these blends, which showed that the blends containing the HIPS‐rich phase gave higher compatibility at the higher shear rates. Surprisingly, the blends containing the HDPE‐rich phase yielded greater compatibility at the lower shear rates. Morphology observations of the blends indicated better compatibility of the blends with increasing SEBS concentration. The relaxation time (T2) values from the pulsed NMR measurements revealed that both polymer blends became more compatible when the SEBS concentration was increased. When integrating all the investigations of compatibility compared with the mechanical properties, it is possible to conclude that SEBS promotes a certain level of compatibilization for several ratios of HIPS/HDPE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 742–755, 2004

Rheological and curing behavior of reactive blending. I. Maleated natural rubber–cassava starch

AbstractMaleated natural rubber (MNR) was prepared and used as a blending composition and a compatibilizer for blending of natural rubber (STR 5L) and cassava starch. The melt rheological behavior in terms of Mooney viscosity, apparent shear stress, and shear viscosity at 100°C were quantified. We found that the pure MNR gave the lower apparent shear stress, shear viscosity than did those of the blends with cassava starch. The rheological data of the MNR blends increased with increasing quantity of cassava starch. The highest value was observed for the blend of MNR. The rheological value was as follows: MNR > STR 5L with MNR (as the compatibilizer) > STR 5L compounds. Furthermore, rheological properties increased with increasing the levels of compatibilizer (MNR). The rheological results were described in terms of intermolecular interaction between the polar groups in the natural rubber and cassava starch molecules. Each rubber blend was compounded, and their curing characteristics were studied. The pure MNR compounds exhibited a long delayed onset of vulcanization for approximately 10 min. The retardation was found, because the accelerator (MBT) reacted with the anhydrides in the compound instead of acting as an accelerator. The retardation was not observed for the compound with the cassava starch. The curing curves for all MNRs were not in equilibrium at a maximum torque, while the pure STR 5L compound gave a curing curve with a maximum torque and a slight reversion. The curing curve for the compound with MNR as the compatibilizer was a combination of the curing curves of MNR and STR 5L. That is, the curve was in equilibrium at the maximum torque and the short delayed action. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2803–2813, 2001