Reactive compatibilization of polypropylene/polyethylene terephthalate blends

The reactive compatibilization of polypropylene/polyethylene terephthalate (PP/PET) blends by addition of glycidyl methacrylate grafted PP (PP-g-GMA) was studied. Two PP-g-GMA copolymers, containing either 0.2 or 1.2 wt% of GMA, were used as interface modifiers. These were incorporated into PP blends (with either 70 or 90 wt% PET), replacing 1/5 of PP in the system. The use of these modifiers changed the blends' tensile mechanical behavior from fragile to ductile. Blend tensile strength was improved by 10% and elongation at break showed 10 to 20-fold increases while stiffness remained constant. Scanning electron micrographs showed the PP average domain size in injection molded specimens to decrease to the micron/sub-micron size upon addition of the GMA modified resins, while the unmodified blends exhibited heterogeneous morphology comprising large lamellae 10–20 μm wide. The low-GMA graft content PP seemed slightly more efficient than the high GMA content PP in emulsifiying PP/PET blends. The GMA grafting level on PP had very limited effects on the blends' mechanical behavior in the range of GMA graft density provided by the two modified resins investigated.     

Polypropylene/polyethylene terephthalate blends compatibilized through functionalization

In attempts to improve the compatibility of polypropylene with polyethylene terephthalate, an acrylic acid functionalized polypropylene was evaluated as the blend component in polyblends containing 40 percent by weight polyethylene terephthalate and compared with an unmodified polypropylene. The preliminary experiments in a batch laboratory mixer were followed by compounding in a co-rotating twin-screw extruder. Additives such as magnesium acetate and p-toluenesulfonic acid were evaluated as catalysts for potential interchange or esterification reactions that could occur in the melt. The blends were characterized through scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and for mechanical properties. The results show that the functionalized polypropylene promotes a fine dispersed phase morphology, improves processability and mechanical properties, and modifies the crystallization behavior of the polyester component. These effects are attributed to enhanced phase interactions resulting in reduced interfacial tension (calculated as a 4-fold decrease). The presence of the additives does not, in general, improve any further the blend morphology and properties, or its processability.     

Effect of pellet size and compatibilization on thermal decomposition kinetic of recycled polyethylene terephthalate/recycled polypropylene blend

This study considers the effects of pellet geometry and compatibilization on its moisture absorption and thermal degradation behavior of recycled polyethylene terephthalate (RPET) and recycled polypropylene (RPP) blend with the ultimate goal of optimizing the design of pellets to enhance their processability. The isoconversion of Flynn–Wall–Ozawa (FWO) was used for the kinetic study, which was suitable for thermal degradation of RPET/RPP blend in N₂ while the second order polynomial function was fitted for thermal oxidative degradation in air. Finer geometries, such as powders, were found to have higher moisture absorption rates due to their large surface area although they could also be easily dried. Furthermore, large surface area of fine powder as well as good interaction between RPP disperse particles and RPET matrix eased to decompose in the presence of oxygen thus accelerated chain breaking during thermal oxidative degradation especially at low heating rate. Meanwhile, larger pellets exhibited higher degradation activation energies, which suggest that they are more resistant to thermal degradation than smaller grains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

增容PP/回收PET共混物的力学性能

采用熔融挤出法制备了聚丙烯(PP)/增容剂/回收聚对苯二甲酸乙二酯(r-PET)共混物,研究了r-PET、不同增容剂和混合增容剂对PP/r-PET共混物力学性能的影响.r-PET提高了PP的拉伸强度、弯曲强度及其模量,但降低了冲击强度;采用马来酸酐接枝聚丙烯(PP-g-MAH)增容,可提高PP/r-PET共混物的拉伸强度、弯曲强度及其模量,但使冲击强度稍有降低;马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)增容或PP-g-MAH/POE-g-MAH混合增容可提高PP/r-PET共混物的冲击强度,且对共混物的拉伸和弯曲强度影响不大.     

Reactive compatibilization and properties of recycled poly(ethylene terephthalate)/polyethylene blends

Summary Blends of recycled poly(ethylene terephthalate) (R-PET) and high-density polyethylene (R-PE), obtained from post-consumer packaging materials, were prepared both by melt mixing and extrusion processes and compatibilized by addition of various copolymers containing functional reactive groups, such as maleic anhydride, acrylic acid and glycidyl methacrylate. The effect of the type and concentration of compatibilizer, as well as the mixing conditions, on the phase morphology, thermal behaviour, rheological and mechanical properties of the blends was investigated. The results indicated that addition (5÷10 pph) of ethylene-co-glycidyl methacrylate copolymer (E-GMA) allows for a marked improvement of processability and physical/mechanical performances of R-PET/R-PE blends. Received: 1 March 2001/Revised version: 15 November 2001/ Accepted: 28 January 2002     

Compatibilizers based on polypropylene grafted with itaconic acid derivatives. Effect on polypropylene/polyethylene terephthalate blends

New types of compatibilizers based on functionalized polypropylene (PP) were synthesized by radical melt grafting either with monomethyl itaconate or dimethyl itaconate. The effect of these new modified PP compounds were tested as compatibilizers in PP/polyethylene terephthalate (PET) blends. Blends with compositions 15/85 and 30/70 by weight of PP and PET were prepared in a single‐screw extruder. Morphology of the compatibilized blends revealed a very fine and uniform dispersion of the PP phase as compared with that of noncompatibilized blends of the same composition, leading to improved adhesion between the two phases. Whereas dimethyl itaconate derived agent showed less activity, the monomethyl itaconate parent compound showed an increase of the impact resistance of PET in PP/PET blend. This was attributed to the hydrophilic nature of the monomethyl itaconate part of this compatibilizer. The tensile strength of PET in noncompatibilized blends gradually decreases as the PP content increases, while blends containing functionalized PP exhibited higher values.     

Mechanical properties of polypropylene/polyamide 6 blends: Effect of manufacturing processes and compatibilization

The properties of polypropylene (PP)/polyamide 6 (PA) blends, obtained by the following two different blending methods, were investigated. Blends of PP/PA and PP/PA/maleic anhydride have been prepared using a twin screw extruder and a fiber cutting, flying and mixing apparatus that directly commingles PP fiber and PA fiber. The properties measured include rheological properties by means of a capillary rheometer, morphologies by scanning electron microscopy, and mechanical properties by a universal testing machine and a high rate impact tester. In the presence of compatibilizer, a marked dispersibility of the polymer blends of PP and PA was observed, and mechanical properties were found to increase as a result of improvement of the interfacial adhesion and the dispersibility. The properties of PP/PA blends manufactured by two different pieces of equipment were shown to be similar in the case of melting both resins. But in particular, superior impact properties were obtained in blends not melting PA fibers as a dispersed phase rather than blends using maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer.     

Compatibilization of recycled poly(ethylene terephthalate) and polypropylene blends: Effect of compatibilization on blend toughness,dispersion of minor phase,and thermal stability

Blending of recycled polyethylene terephthalate (RPET) from waste bottles with polypropylene (PP) was performed in an attempt to enhance the processability of RPET. The idea of blending RPET with PP sprouted from the intention of recycling PET bottles together with their PP‐based caps. Therefore, preliminary blending of RPET with neat PP (RPET/PP) was performed at various PP and compatibilizer contents. Morphological analyses on the extruded pellets of uncompatibilized blends indicate that the PP particle size and state of dispersion at skin and core regions were vastly different. The particles at the skin were at least 10 times smaller than that at the core although the size distribution was very wide. With the incorporation of just 5 phr of compatibilizer, the particles at the core region became significantly smaller and appeared to emulate that of the skin region. Furthermore, the overall homogeneity of the blends was vastly improved irrespective of PP content in the blend. The reduction in particle size and improved homogeneity inherently reduced stress concentration points and enhanced the mechanical performance of the blends. More importantly, the incorporation of PP into RPET significantly increased the degradation temperature of the blends, provided the dispersion of PP phase in RPET was excellent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In situ compatibilization of polypropylene–polyethylene blends: a thermomechanical and spectroscopic study

Polypropylene (PP) and low density polyethylene (LDPE) were melt blended in proportions of 75/25, 50/50 and 25/75 w/w, respectively. Poly(propylene-g-maleic anhydride) (PP-g-MA) with 0.8 mol% maleic anhydride content and poly(ethylene-co-vinyl alcohol) (EVAL) with 7.5 mol% vinyl alcohol content were added at a 50/50 w/w proportion as in situ reactive compatibilizers. Four series of compatibilized blends were produced containing 2.5, 5, 10 and 20 wt% compatibilizer in the final blend. The compatibilization reaction was followed by a torque increase during mixing and by FTi.r. spectroscopy. A notable improvement in tensile strength, elongation at break and impact strength was observed for all blends after compatibilization and, in particular, for the blends containing 10 wt% compatibilizer. Scanning electron microscopy (SEM), aided by micro-Raman spectroscopy, was used for investigating the morphology of the blends.     

Engineering properties of compatibilized polypropylene/liquid crystalline polymer blends

Polypropylene (PP) and Vectra A950, a thermotropic liquid crystalline polymer (LCP), blends were prepared in a single‐screw extruder with the variation in Vectra A950 content in presence of fixed amount (2%, with respect to PP and LCP mixture as a whole) of ethylene‐acrylic acid (EAA) copolymer as a compatibilizer. Mechanical analysis of the compatibilized blends within the range of LCP incorporations under study (2–10%) indicated pronounced improvement in the moduli, ultimate tensile strength (UTS), and hardness. Fourier transform infrared (FTIR) spectroscopy studies revealed the presence of strong interaction through H‐bonding between the segments of Vectra A950 and the compatibilizer EAA. Morphological studies performed by scanning electron microscopy (SEM) manifested the development of fine fibrillar morphology in the compatibilized PP/Vectra A950 blends, which had large influence on the mechanical properties. Differential scanning calorimetry studies showed an initial drop of the melting point of PP in the presence of EAA followed by enhancement of the same in presence of Vectra A950. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP. Rheological studies showed that a very small quantity of Vectra A 950 was capable of reducing the melt viscosity of PP particularly in the lower shear rate region and hence facilitated processibility of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improving the foaming and mechanical properties of the in situ microfiber-reinforced polyethylene terephthalate/polypropylene composites through compatibilization

The in situ microfiber-reinforced polyethylene terephthalate/isotactic polypropylene (15/85, w/w) composite (PET/iPP MRC) was successfully obtained through the micro-nano-laminating co-extrusion by using polypropylene-grafted-glycidyl methacrylate (PP-g-GMA) as a compatibilizer. The effect of the compatibilizer on the rheological behavior, micromorphology of PET/iPP MRC, foaming capability and the mechanical properties of foamed PET/iPP MRC was investigated. Extensional rheology measurement revealed the strain hardening of PET/iPP MRC is more obviously than iPP and with compatibilizer added. Scanning electron microscope observation indicated that the introduction of PP-g-GMA compatibilizer can improve the compatibility between PET and PP and subsequently lead to the decrease of diameter of PET microfibers. In addition, the incorporating of PP-g-GMA compatibilizer can also decrease the diameter and enhance the cell density of PET/iPP MRC cell. Both the tensile strength and the impact strength of the PET/iPP MRC foam are higher than that of the iPP foam, and improved with the compatibilizer added.     

Studies on blends of polyethylene terephthalate with bisphenol-a-polycarbonate and polypropylene

Moldability and mechanical properties of polyethylene terephthalate (PET) under normal molding conditions were found to improve significantly when it was blended with bisphenol-A-polycarbonate (PC) and polypropylene (PP) to form ternary polymer blend systems. DSC results of these blends revealed that the PET and PC components formed a miscible blend while PP being incompatible with them, formed a separate phase. PP was also found to form a sleeve around the PET-PC miscible phase and, thereby, showed a skin-core type of morphology. Variations of mechanical properties with varying amounts of PP was measured keeping the ratio of PET and PC constant. Tensile and flexural properties of the blends decrease with the amount of PP. Notched impact strength increases up to a certain level of PP and then decreases, while the unnotched values decrease gradually. The effect of annealing on the mechanical properties of these blends have been discussed on the basis of the increased crystallinity of some of the components.     

Mechanical and thermal properties of polypropylene/recycled polyethylene terephthalate/chopped rice husk composites

The various ratios of recycled polyethylene terephthalate (rPET) into polypropylene (PP) filled with 40 parts chopped rice husk per hundred part of polymer have been studied. Composites were prepared using a corotating twin screw extruder at temperature zones of 165–215, well below 250°C (rPET mp temperature) and characterized by mechanical and thermal properties. To improve the compatibility between different components, PP grafted with maleic anhydride was added as a coupling agent in all the compositions studied. The results showed that the addition of rPET improved the tensile and flexural modulus and impact strength of the composite while reducing its tensile and flexural strength. The scanning electron microscopy micrographs of samples in the injection direction showed that some particle shaped rPET inside the composites appear as drawn fibrils and some appear as plates. Differential scanning calorimetric studies showed that the addition of rPET particles to the composites decrease the PP crystallization temperatures. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical and thermal properties of exfoliated graphite nanoplatelets reinforced polyethylene terephthalate/polypropylene composites

Exfoliated graphite nanoplatelets (GNP) reinforced composites materials based on blend of poly(ethylene terephthalate) (PET) and polypropylene (PP) were prepared by melt extrusion followed by injection molding. 10 parts per hundred resin (phr) styrene‐ethylene‐butylene‐styrene‐g‐maleic anhydride was added to the base formulation PET/PP (70/30) as a compatibilizer. PET/PP/GNP composites 0–5 phr were prepared and characterized using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared (FTIR) spectroscopy analysis. The morphological studies revealed a homogenous dispersion of GNPs in PET/PP blends up to 3 phr loading after which agglomeration occurred. Flexural strength was enhanced by 80% at 3 phr GNPs loading which was the highest value obtained. Interestingly, the highest value for the impact strength was also recorded at 3 phr loading. The thermal stability of the composites were generally improved at all filler loading with the highest at 3 phr. From the overall results, it is clear that the optimum concentration of GNPs in the PET/PP/GNP system in terms of both mechanical and thermal properties was 3 phr loading. Although, the mechanical and thermal properties of the composites were improved, the FTIR analysis did not reveal any chemical interaction between GNP and the polymer matrix. POLYM. COMPOS., 35:2029–2035, 2014. © 2014 Society of Plastics Engineers     

Effects of mixing porcedures on properties of compatibilized polypropylene/nylon 6 blends

The paper consides the effects of compatibilization with maleic anhydride grafted polypropylene (PP-g-MAH) on the propertie of immiscible blends of polypropylene (PP) and nylon 6 (N6). We prepared the blends by three different mixing processes; single-step blending, two-step blending with reactive premixing, and two-step blending with nonreactive premixing, to determine the effective mixiing process for fine morphological structure thermal stability, and mechanical properties. Dynamic melt reheological properties were measured to examine the modification of elastic properties by the compatibilizer. In addtion, thermal analysis was also carried out to detect the change in crystallization and thereby to probe the degree of compatibilizaton. The results show that compatibilized blends prepared by teh single-step process exhibit improved phase morphology, thermal stability, and mechanical properties for dried conditions, compared with other blend types. Finally, the water absorption test indicates that the added compatibilizer yields enhanced water resistance in spite of the strong intrinsic hydrophilicity of N6. In particular, two-step blending with reactive premixing is most effective in improving water resistance and reducing degradation of mechanical properties after moisture absorption.     

Surface energy of polypropylene/polysulfone compatibilized blends

Various surface energy models were applied to environmentally friendly membrane blends composed of polypropylene and polysulfone, with and without the addition of functional polyolefins. The Zisman and van Oss models gave comparable values for these polymer blend systems, and the Owens/Wendt model gave slightly lower values. There was effectively no variability in the surface energy values obtained by using two different processing methods. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Morphology and mechanical properties of PET/PE blends compatibilized by nanoclays: Effect of thermal stability of nanofiller organic modifier

Poly(ethylene terephtalate)/poly(ethylene) (PET/PE) blends (80/20 wt %) were prepared by melt‐extrusion and compatibilized by addition of nanoclays. Two commercially available organically modified montmorillonites (Cloisite© 10A and 30B) were chosen as reference and a third one was specially organomodified at lab scale with a thermally stable phosphonium surfactant using conventional cationic exchange reaction. The size of the dispersed polymer phase (PE droplets) and the ductility of the blends depend more on the thermal stability of the surfactant of the organomodified clay than on the enthalpic interactions between the blend components and the surfactants used for the modification of the clays. The highest mechanical properties (yield stress and elongation at break) and the better compatibilization efficiency (smallest dispersed PE droplets) were observed in the presence of phosphonium organomodified montmorillonite compared to other less thermally stable commercial organoclays. The analysis of the thermal stability, morphology, and mechanical properties of PET/PE blends containing the surfactants alone in the absence of clay made it possible to evidence separately the effects of the surfactant and of the nanofiller. The role of the surfactant as compatibilization agent was demonstrated. In the absence of nanofiller, the finest morphological and highest ductility were again obtained with the phosphonium surfactant which is the most thermally stable. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of chemical and mechanical compatibilization on structure and properties of polyethylene/polyamide blends

LDPE/PA6 binary blends and LDPE/PA6/compatibilizer ternary blends were prepared in a Brabender extruder, equipped with a prototype static mixer. Compatibility of the components was estimated by rheological properties (viscosity and a melt flow index), and observations of the structure were made with the help of scanning electron microscopy and tensile strength. It was found that the blends' structure and properties are dependent on the recipe content of the polymer blends and the conditions of their manufacturing. Uniformity of the blends of the thermodynamically immiscible polymers was improved by using a prototype static mixer giving mechanical compatibilization and a compatibilizer giving chemical compatibilization. LDPE grafted with a maleic anhydride (LDPE-g-MAH) was used as a compatibilizer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 719–727, 1998