In‐situ ultrasonic compatibilization of unvulcanized and dynamically vulcanized PP/EPDM blends

Dynamically vulcanized PP/EPDM blends were treated by high‐intensity ultrasonic waves during extrusion. These blends were compared with unvulcanized PP/EPDM blends that were treated by ultrasound during extrusion and then dynamically vulcanized. Die pressure and power consumption were measured. The effects of different gap sizes, ratio of components, and number of ultrasonic horns were investigated. The rheological properties, morphology and mechanical properties of the blends with and without ultrasonic treatment were compared. The results obtained indicated that ultrasonic treatment induced thermo‐mechanical degradation, causing enhanced molecular transport and chemical reactions at the interfaces, thus leading to in‐situ compatibilization, which is evident by the morphological and mechanical property studies. Processing conditions were established for enhanced in‐situ compatibilization of the PP/EPDM blends that were either originally dynamically vulcanized and then ultrasonically treated or first treated and then dynamically vulcanized. Polym. Eng. Sci. 44:2019–2028, 2004. © 2004 Society of Plastics Engineers.     

Compatibilization of polypropylene/nylon 6 blends with a polypropylene solid‐phase graft

The compatibilization of polypropylene (PP)/nylon 6 (PA6) blends with a new PP solid‐phase graft copolymer (gPP) was systematically studied. gPP improved the compatibility of PP/PA6 blends efficiently. Because of the reaction between the reactive groups of gPP and the NH₂ end groups of PA6, a PP‐g‐PA6 copolymer was formed as a compatibilizer in the vicinity of the interfaces during the melting extrusion of gPP and PA6. The tensile strength and impact strength of the compatibilized PP/PA6 blends obviously increased in comparison with those of the PP/PA6 mechanical blends, and the amount of gPP and the content of the third monomer during the preparation of gPP affected the mechanical properties of the compatibilized blends. Scanning electron microscopy and transmission electron microscopy indicated that the particle sizes of the dispersed phases of the compatibilized PP/PA6 blends became smaller and that the interfaces became more indistinct in comparison with the mechanical blends. The microcrystal size of PA6 and the crystallinity of the two components of the PP/PA6 blends decreased after compatibilization with gPP. The compatibilized PP/PA6 blends possessed higher pseudoplasticity, melt viscosity, and flow activation energy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 420–427, 2004     

Investigations on the formation of composites by injection molding of PA6 and different grafted polypropylenes and their blends

Blends of different types of polypropylenes (PP) with polyamide 6 (PA6) were produced by extrusion. The PPs used were a PP homopolymer, a maleic anhydride‐grafted homopolymer, and an acrylic acid‐grafted homopolymer. The blends were characterized by DSC measurements, selective extraction, infrared spectroscopy, REM microscopy, melt rheology, and their mechanical properties. Three types of interactions in the blends as well as in two‐component composites mold by the core‐back process could be identified. Blends of PP with PA6 were not compatible, and two‐component bars could not be produced. Blends of PPgAA and PA6 were made compatible during reactive extrusion. Two‐component bars could be produced only with a blend containing 50 wt % PA6. The composite formation was based on the interdiffusion of PA6 in both components and the reactive compatibilization in the blends. Blends of PPgMAn were also compatibilized during reactive extrusion. The composite formation on two‐component injection molding was based on two mechanisms: the interdiffusion at sites, where PA6 chains of both the components came into contact, and an interfacial reaction, where PPgMAn and PA6 came into contact. The interfacial reaction was supported by the high mobility of the first component at the temperature of the melt of the second component. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2992–2999, 2006     

Wirkung von Diisocyanat als reaktiver Koppler in TPU/PA6-Blends

To improve materials performance like the temperature of deformation under flexural load of thermoplastic polyurethanes (TPU) blending with thermoplastics is sensible. A good compatibilization and phase adhesion of thermodynamical incompatible blend-components can be achieved by the use of the right coupling agents. In the case of blends with TPU and PA6 diisocyanate is given into the melt during the extrusion. Through the chemical reactions effects of compatibilization are achieved in the cases of blends with polyesterpolyurethanes and PA6 produced by extrusion and injection moulding and by reactions in solution, too. These could be perceived as consequence of MDI-initiated reactions within the phase boundary layer. The possible reactions with the PA6-phase will be discussed by the use of a model-system made in solution. No effects of compatibilization by MDI could be proved in the polyetherpolyurethan/PA6-system. The chemical characterization of the blends was realized by GPC and FTIR whereas the properties of the morphology are proved with the help of DSC, DMA and transmission electron microscopy (TEM).     

原位增容PA6/PE-HD共混物的性能研究

在双螺杆挤出机上通过原位增容反应挤出制备了聚酰胺6(PA6)/高密度聚乙烯(PE-HD)共混物。通过力学性能测试、扫描电子显微镜观察和Molau实验,研究了PE-HD含量对PA6/PE-HD共混物的力学性能和体系增容作用的影响。结果表明,PE-HD与马来酸酐(MAH)在挤出共混过程中原位生成了PE-HD-g-MAH,其对PA6/PE-HD共混物有较好的增容作用;PA6/PE-HD共混物的力学性能与界面形态均有较大改善,吸水率有所降低。     

新型聚丙烯固相接枝物增容聚丙烯／尼龙6共混物的研究

研究了聚丙烯与马来酸酐,甲基丙烯酸甲酯及第三单体的固相接枝共聚物「ＰＰ－ｇ（ＭＡＨ－ＭＭＡ－ＴＭ）」对聚丙烯／尼龙６（ＰＰ／ＰＡ６）共混物的增容作用。结果表明,新表明ＰＰ固相接枝物能有效地改善ＰＰ／ＰＡ６共混物的相容性,增加两相界面的粘合作用,显著提高共混物的力学性能,增容后体系假塑性增加,熔体粘度上升,活化能增加。     

In situ compatibilization of PP/EPDM blends during ultrasound aided extrusion

Blends of isotactic polypropylene (iPP) and uncured ethylene-propylene diene rubber (EPDM) of various concentrations were treated by high power ultrasonic waves during extrusion. Die pressure and power consumption were measured. The effects of different gap sizes, blend ratios and number of ultrasonic horns were investigated. The rheological properties, morphology and mechanical properties of the blends with and without ultrasonic treatment were studied. In situ compatibilization of the blends was observed as evident by their more stable morphology after annealing, improved mechanical properties and IR spectra. The obtained results indicated that ultrasonic treatment induced the thermo-mechanical degradations and led to the possibility of enhanced molecular transport and chemical reactions at the interfaces. Processing conditions were established for enhanced in situ compatibilization of the PP/EPDM blends.     

In situ compatibilization of PEN/LCP blends by ultrasonic extrusion

In situ compatibilization of immiscible blends of PEN and thermotropic LCP was achieved by the ultrasonically‐aided extrusion process. Ultrasonically‐treated PEN underwent degradation, leading to a decrease of its viscosity. Viscosity of LCP was unaffected by ultrasonic treatment. Because of reduced viscosity ratio of PEN to LCP at high amplitude of ultrasonic treatment, larger LCP domains were observed in molding of the blends. LCP acted as a nucleating agent, promoting higher crystallinity in PEN/LCP blends. Ultrasonically‐induced copolymer formation was detected by MALDI‐TOF mass spectrometry in the blends. Ultrasonic treatment of 90/10 PEN/LCP blends improved interfacial adhesion in fibers spun at intermediate draw down ratios (DDR), improving their ductility. The lack of improvement in the mechanical properties of fibers spun at high DDR after ultrasonic treatment was attributed to the disturbance of interfacial copolymer by high elongation stresses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Devolatilization: A critical sequential operation for in situ compatibilization of immiscible polymer blends by one-step reactive extrusion

The main objective of this study was to show that an efficient removal of residual monomers is very important for in situ compatibilization of immiscible polymer blends by one step reactive extrusion. One-step reactive extrusion means that when compatibilizing two immiscible polymers with one polymer containing potential functional groups and the other being chemically inert with respect to these functional groups, functionalization of the chemically inert polymer and its subsequent interfacial reaction with the functional polymer are accomplished in a single extrusion process. Two model blend systems were chosen: polypropylene/poly(butylene terephthalate) (PP/PBT) and high density polyethylene/polyamide 6 (HDPE/PA6). A co-rotating intermeshing twin screw extruder was used to process these blends. Glycidyl methacrylate (GMA) and maleic anhydride (MA) were used to functionalize PP and HDPE, respectively. Results showed that the mechanical properties of both blends in terms of elongation at break and impact strength were improved to a much greater extent with up-stream devolatilization compared with down-stream devolatilization.     

Improvement of mechanical properties for PP/PS blends by in situ compatibilization

The effect of the in situ compatibilization on the mechanical properties of PP/PS blends was investigated. The application of Friedel-Crafts alkylation reaction to the PP/PS-blend compatibilization was assessed. Styrene/AlCl₃ was used as catalyst system. The graft copolymer (PP-g-PS) formed at the interphase showed relatively high emulsifying strength. Scission reactions, occurring in parallel with grafting, were verified for PP and PS at high catalyst concentration, but no crosslinking reactions were detected. Tensile tests were performed on dog-bone specimens of the blends. Both elongation at break and toughness increased with catalyst concentration. At 0.7% AlCl₃, a maximum was reached, which amounted to five times the value of the property for the uncompatibilized blend. At higher catalyst concentrations these properties decreased along with the PP molecular weight due to chain-scission reactions. On the other hand, the tensile strength did not change with the catalyst concentration. The in situ compatibilized blends showed considerable improvement in mechanical properties, but were adversely affected by chain scissions at high catalyst contents.     

聚丙烯熔融接枝马来酸二丁酯增容聚丙烯／尼龙6的研究

研究了聚丙烯（ＰＰ）与马来酸二丁酯（ＤＢＭ）的接枝共聚物ＰＰｇＤＢＭ对聚丙烯／尼龙６（ＰＰ／ＰＡ６）共混物的增容作用。研究表明,ＰＰｇＤＢＭ是ＰＰ／ＰＡ６共混体系的有效增容剂,由于共混过程中就地生成ＰＰｇＰＡ６,改善了共混物的相容性,增加了两相界面的粘合,使分散相粒径减小,分散更均匀,提高了共混物的力学性能。增容剂接枝率的高低对增容效果有一定影响,接枝物中残留单体不影响增容效果     

Effects of compatibilization of oxidized polypropylene on PP blends of PP/PA6 and PP/talc

The influence of compatibilization on the dynamic mechanical properties of polypropylene (PP) binary blends with polyamide‐6 (PA6), Talc, and oxidized PP (OPP) was investigated. The oxidation of PP homopolymer was performed in a internal mixer by using air as a oxidizing agent (under atmospheric pressure) and dodecanol‐1 as an accelerator at 180°C for 6½ h [Abdouss, M.; Sharifi‐Sanjani, N.; Bataille, P. J Appl Polym Sci 1999, 36, 10]. In the blends, OPP was used as a blend component and compared with PP over the whole concentration range. Pressed film blends of PP/OPP, PP/OPP/Talc, and PP/OPP/PA6 were examined by dynamic mechanical analyzer, thermal gravimetry analysis, and scanning electron microscopy. Mechanical properties such as tensile strength, modulus of elasticity, elongation, melt flow index, and hardness of the blends were measured. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2871–2883, 2004     

Dynamic mechanical properties of polypropylene–polyamide blends: Effect of compatibilization

The influence of compatibilization on the dynamic mechanical properties of polypropylene (PP) binary blends with polyamide-11 (PA) has been investigated. In the blends an acrylic acid functionized PP was used as a blend component and compared with nonfunctionized PP over the who concentration range. The results demonstrate that the use of the functionized PP instead of the unmodified one produced blends with different dynamic mechanical properties due to adhesion enhancement between the two phases. The storage moduli E′ of the compatibilized blends vary nearly linearly as a function of composition over a broad temperature region, whereas those of the noncompatibilized ones deviate greatly from linearity, specially at about 50/50 ratio, at which a minimum exists at about room temperature. While the dynamic testing gives no evidence for the variation in the glassy transition temperatures (peak maxima) of the components (PP and PA) in the two types of blends, both the loss modulus (E″) and the loss factor (tan δ) data indicate that the compatibilized blends differ from the noncompatibilized ones mainly in the glassy transition (βrelaxation) process of the PA phase, suggesting that the compatibilization of the blends seems to influence the PA phase more than the PP phase included. But, for the β-relaxation behavior of the PA in the modified blends, the tan δ spectrum shows a more complex pattern than does the E″. These results are discussed in terms of the morphological texture of the blends and possible chemical or physical interactions between the two consituent polymers.     

Synchronous toughening and reinforcing of polypropylene with ultrahigh‐molecular‐weight polyethylene via melt blending: Mechanical properties,morphology, and rheology

Blending systems based on polypropylene (PP) and ultrahigh‐molecular‐weight polyethylene (UHMWPE) were prepared via a melt extrusion by the four‐screw and the twin‐screw extruders, respectively. The mechanical evaluation demonstrated that the synchronous toughening and reinforcing effects could be achieved from the combination of the PP and the UHMWPE, in which the toughness and the tensile properties could be improved with increasing the UHMWPE content, and achieved optimal values at a weight ratio of PP/UHMWPE (85/15). EPDM can be used as a compatibilizer to improve the compatibility and the interfacial adhesion between the PP and the UHMWPE. This resulted in more effective toughening and reinforcing effects. In contrast, for the PP/UHMWPE blends prepared by the normal twin‐screw extruder, the poor dispersion capacity for the UHMWPE resulted in a deterioration of all mechanical parameters. Morphological observation revealed that the UHMWPE domain was well distributed as tiny particles in the PP matrix, which was confirmed by the differential scanning calorimetry analysis. The toughening effect was attributed to the energy dissipation caused by these rigid tiny particles that detached from the matrix to initiate the local matrix shear yield and formed the void. Rheological investigation demonstrated that there was an interesting composition dependence of viscosity, for which the melt viscosities of the PP/UHMWPE blends decreased when 5 wt % UHMWPE was added, and then began to increase as the UHMWPE content continued to increase. However, this dependence on composition became weaker because of the compatibilization of the EPDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3498–3509, 2006     

Compatibilization of polypropylene/polyamide 6 blends using new synthetic nanosized talc fillers: Morphology,thermal, and mechanical properties

New synthetic nanotalc and a commercially available natural fine talc (Luzenac© A3) were chosen in order to establish a comparative study in terms of their contributions on the improvement of the morphology as well as the final properties of PP/PA6 blends prepared by melt processing. At first, the TEM and SEM micrographs showed that both talc particles have a preferential affinity for the more hydrophilic polyamide 6 phase compared with the continuous PP matrix. Moreover, in both cases, the addition of talc fillers induces a significant decrease of the size of the PA6 domains but the better compatibilization efficiency was obtained in the presence of synthetic nanotalc particles. In this work, the positive change induced by the talc nanofillers on the crystallization kinetics and final morphology was highlighted. In addition, compared with natural talc, a highly level of dispersion of talc layers has been obtained with the synthetic nanotalc which is more hydrophilic. Thus, this better dispersion greatly improves the thermal stability of PP/PA6 blends and leads to better mechanical properties (+ 40% in Young's modulus). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40453.     

Novel approach for the preparation of a compatibilized blend of nylon 11 and polypropylene with polyhydroxybutyrate: Mechanical,thermal, and barrier properties

This article comprises of the interaction in the immiscible polymer system of nylon 11 (PA 11), polypropylene (PP), and polyhydroxybutyrate (PHB). Reactive compatibilization extrusion method with maleic anhydride-grafted polypropylene (PP-g-MA) is used to achieve compatibility within the polymer. To further improve the interaction of the blend at interphase, PHB was added as a dispersive phase in a concentration varying from 10 to 40% of the total batch. Addition of PHB motives the excellent dispersion of PP chain in PA 11 and assures the compatibility between the phases of PA 11 and PP-g-MA. The entire system of tertiary and binary phases was blended in a twin-screw extruder at different composition. The macro-optimal tensile strength, Young's modulus, bending strength, and notched impact strength of PA11/PP systems were found to be superior as compared to their noncompatibilized systems. The degradation temperature of the blends of PA11/PP and PA11/PHB/PP with and without compatibilizer was evaluated by thermogravimetric analysis (TGA). It was found that the high temperature of degradation was required for compatibilized ternary blend than that of the compatibilized binary blend. The distortion temperature of the systems was studied with the help of heat deflection temperature (HDT) and found to be advanced for blend having a higher concentration of the dispersed phase. Differential scanning calorimetry (DSC) was used to determine the % crystallinity, melting, and crystallization temperature of this system. Chemical resistance and barrier properties of the different compatibilized and noncompatibilized blends were studied. PHB dispersed phase with a reactive compatibilizer cause enhancement in chemical resistance and barrier properties of the blend. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48152.     

Effect of clay on the morphology of blends of poly(propylene) and polyamide 6/clay nanocomposites

PP/NPA6 blends composed of poly(propylene) (PP) and polyamide 6/clay nanocomposites (NPA6) were prepared by twin‐screw extrusion and melt‐drawn into ribbons by a ribbon extrusion process. The influence of clay on the morphology of PP/NPA6 ribbons was investigated by means of field‐emission scanning electron microscopy and optical microscopy. The results show that at low clay content (3, 5 wt%), NPA6 exhibited continuous lamellar structure in PP as pristine PA6 did in a PP/PA6 blend, but at a higher clay content (10 wt%) only ellipsoids or elongated ellipsoids were observed. In order to explain the morphological difference, two factors, ie the compatibilization effect and melt rheology, have been taken into consideration. It has been found that both factors, and probably mainly the variation in melt rheology, were responsible for the morphological difference in the PP/NPA6 blends with different clay contents under the extensional flow field. Copyright © 2004 Society of Chemical Industry     

Blending of immiscible polymers in a mixing zone of a twin screw extruder—effects of compatibilization

The dependence of the morphology development of physical as well as of reactive compatibilized polypropylene/polyamide 6 (PP/PA6) blends in a mixing zone of a co‐rotating twin screw extruder on blend composition and screw rotational speed was investigated. A special process analytical set‐up based on a co‐rotating twin screw extruder was used, which allowed melt sampling from different positions along the operating extruder in time periods less than 10 seconds. It has been shown that the disperse particle sizes in physical blends depend crucially on the blend composition because of the increasing influence of coalescence with an increasing concentration of the disperse phase. Furthermore, the morphology of physical PP/PA6 blends depends strongly on their rheological properties. In contrast, the influence of the screw rotational speed on the morphology is minor. The resulting particle size in a mixing zone is achieved already after a short screw length. The particle size of compatibilized blends is significantly smaller than in physical blends because of the better conditions for drop break‐up and the suppression of coalescence effects. Due to this, compatibilization has a stronger influence on the blend morphology than a variation of process or rheological conditions with physical blends. Furthermore, the compatibilization leads to a concurrent crystallization of the PA6 phase with the PP phase.     

Co-continuous and encapsulated three phase morphologies in uncompatibilized and reactively compatibilized polyamide 6/polypropylene/polystyrene ternary blends using two reactive precursors

Phase morphology development in ternary uncompatibilized and reactively compatibilized blends based on polyamide 6 (PA6), polypropylene (PP) and polystyrene (PS) has been investigated. Reactive compatibilization of the blends has been performed using two reactive precursors; maleic anhydride grafted polypropylene (PP-g-MA) and styrene maleic anhydride copolymer (SMA) for PA6/PP and PA6/PS pairs, respectively. For comparison purposes, uncompatibilized and reactively compatibilized PA6/PP and PA6/PS binary blends, were first investigated. All the blends were melt-blended using a co-rotating twin-screw extruder. The phase morphology investigated using scanning electron microscope (SEM) and selective solvent extraction tests revealed that PA6/PP/PS blends having a weight percent composition of 70/15/15 is constituted from polyamide 6 matrix in which are dispersed composite droplets of PP core encapsulated by PS phase. Whereas, a co-continuous three-phase morphology was formed in the blends having a composition of 40/30/30. This morphology has been significantly affected by the reactive compatibilization. In the compatibilized PA6/(PP/PP–MA)/(PS/SMA) blends, PA6 phase was no more continuous but gets finely dispersed in the PS continuous phase. The DSC measurements confirmed the dispersed character of the PA6 phase. Indeed, in the compatibilized PA6/(PP/PP–MA)/(PS/SMA) blends where the PA6 particle size was smaller than 1 μm, the bulk crystallization temperature of PA6 (188 °C) was completely suppressed and a new crystallization peak emerges at a lower temperature of 93 °C as a result of homogeneous nucleation of PA6.     

Continuous ultrasonic process for in situ compatibilization of polypropylene/natural rubber blends

The immiscible polypropylene (PP)/natural rubber (NR) blends of various concentrations were prepared by using a twin-screw extruder. The prepared blends were passed through the reactor where they were ultrasonically treated by an extrusion process. Mechanical properties and rheology of the obtained blends were studied, along with morphology by using the scanning electron microscopy and the atomic force microscopy (AFM). Mechanical properties of the treated blends were found to improve significantly in comparison with those of untreated blends. Under most treatment conditions, no significant differences in the viscosity of the treated and untreated blends were observed. The AFM studies revealed the development of interfacial layers, interfacial roughening and improved interfacial adhesion between PP and NR phases in the blends subjected to ultrasonic treatment. At the same time weak adhesion and delamination at the interface were found in the untreated blends. The improved interfacial adhesion, morphology and mechanical properties are believed to be due to the formation of in situ copolymer at the interface of two immiscible polymers caused by an ultrasonic treatment without the use of any chemicals.