Morphology,thermal behavior,and mechanical properties of PA1010/PP and PA 1010/PP-g-GMA blends

The modification of polypropylene (PP) was accomplished by melt grafting glycidyl methacrylate (GMA) on its molecular chains. The resulting PP-g-GMA was used to prepare binary blends of polyamide 1010 (PA1010) and PP-g-GMA. Different blend morphologies were observed by scanning electron microscopy (SEM) according to the nature and content of PA1010 used. Comparing the PA1010/PP-g-GMA and PA1010/PP binary blends, the size of the domains of PP-g-GMA were much smaller than that of PP at the same compositions. It was found that mechanical properties of PA1010/PP-g-GMA blends were obviously better than that of PA1010/PP blends, and the mechanical properties were significantly influenced by wetting conditions for uncompatibilized and compatibilized blends. A different dependence of the flexural modulus on water was found for PA1010/PP and PA1010/PP-g-GMA. These behaviors could be attributed to the chemical interactions between the two components and good dispersion in PA1010/PP-g-GMA blends. Thermal and rheological analyses were performed to confirm the possible chemical reactions taking place during the blending process. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1489–1498, 1997     

Mechanical properties,morphological structure,and thermal behavior of dynamically photocrosslinked PP/EPDM blends

A dynamically photocrosslinked polypropylene (PP)/ethylene–propylene–diene (EPDM) rubber thermoplastic elastomer was prepared by simultaneously exposing the elastomer to UV light while melt‐mixing in the presence of a photoinitiator as well as a crosslinking agent. The effects of dynamic photocrosslinking and blend composition on the mechanical properties, morphological structure, and thermal behavior of PP/EPDM blends were investigated. The results showed that after photocrosslinking, tensile strength, modulus of elasticity, and elongation at break were improved greatly. Moreover, the notched Izod impact strength was obviously enhanced compared with corresponding uncrosslinked blend. Scanning electron microscopy (SEM) morphological analysis showed that for uncrosslinked PP/EPDM blends, the cavitation of EPDM particles was the main toughening mechanism; whereas for dynamically photocrosslinked blends, shear yielding of matrix became the main energy absorption mechanism. The DSC curves showed that for each dynamically photocrosslinked PP/EPDM blend, there was a new smaller melting peak at about 152°C together with a main melting peak at about 166°C. Dynamic mechanical thermal analysis (DMTA) indicated that the compatibility between EPDM and PP was improved by dynamic photocrosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3371–3380, 2004     

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     

Effect of silane‐grafted polypropylene on the mechanical properties and crystallization behavior of talc/polypropylene composites

Talc‐filled polypropylene (PP) composites coupled with silane‐grafted polypropylene (PP‐g‐Si) were prepared. Effect of PP‐g‐Si on the mechanical properties, crystallization, and melting behavior of PP composites was investigated. Compared with the uncoupled composites, the mechanical properties of Talc/PP composites coupled with a small amount of PP‐g‐Si were increased to some extent. Meanwhile, PP‐g‐Si can promote crystallization rate and increase crystallization temperature of PP in the composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2974–2977, 2000     

Polypropylene–phenol formaldehyde‐based compatibilizers. II. Application in PP/PA6 75/25 (wt/wt) blends

A new class of compatibilizers suitable for blends or alloys of polypropylene and engineering polymers having aromatic residues or functionality complimentary to hydroxyl were evaluated in blends of isotatctic polypropylene (PP) and polyamide 6 (PA6). The compatibilizer consisted of a PP part with a phenol formaldehyde (PF) polymer grafted onto it. In this study, various combinations of the polymer parameter of each compatibilizer building block were examined. Based on the same loading, the compatibilizer with low molecular weight PP and high content of high molecular weight PF was observed to be the most efficient. A compatibilizer content of up to 7.5% by weight gave significant reduction in the average particle size of the dispersed PA phase. Similarly, corresponding improvements in the mechanical properties were observed as the average particle size was reduced. For some of the blends, more than additive improvement in the mechanical properties were achieved. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 355–360, 2000     

Toughening of PP/EPDM blend by compatibilization

To improve the mechanical properties of blends of polypropylene (PP) and terpolymer of ethylene–propylene–diene (EPDM), a triblock copolymer, (PP‐g‐MAH)‐co‐[PA‐6,6]‐co‐(EPDM‐g‐MAH), was synthesized by coupling reaction of maleic anhydride (MAH)‐grafted PP (PP‐g‐MAH), EPDM‐g‐MAH, and PA‐6,6. The newly prepared block copolymer brought about a physical interlocking between the blend components, and imparted a compatibilizing effect to the blends. Introducing the block copolymer to the blends up to 5 wt % lead to formation of a β‐form crystal. The wide‐angle X‐ray diffractograms measured in the region of 2θ between 10° and 50° ascertained that incorporating the block copolymer gave a new peak at 2θ = 15.8°. The new peak was assigned to the (300) plane spacings of the β‐hexagonal crystal structure. In addition, the block copolymer notably improved the low‐temperature impact property of the PP/EPDM blends. The optimum usage level of the compatibilizer proved to be 0.5 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1267–1274, 2000     

Morphological and mechanical properties of PP/ABS blends compatibilized with PP‐g‐acrylic acid

Polypropylene (PP) and acrylonitrile–butadiene–styrene (ABS) blends were prepared by a melt extrusion process. PP‐g‐acrylic acid was used as a compatibilizer. Blends with various compositions of PP, compatibilizer, and ABS were prepared and studied for morphological and mechanical properties. PP‐rich ternary blends showed good morphological and mechanical properties. The use of 5 wt % PP‐g‐acrylic acid as a compatibilizer resulted in a fine and homogeneous dispersion of the ABS phase in the PP phase. The experimental data of the tensile modulus showed good agreement in PP‐rich compositions with that generated from Kerner's model with perfect adhesion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1731–1741, 2001     

Compatibilized blends of PVC/PA12 and PVC/PP containing poly(lauryl lactam‐block‐caprolactone)

Specially designed block copolymers have played a role as compatibilizing agents in the system of immiscible polymer blends. We applied lauryl lactam (LA)–caprolactone (CL) block copolymer [P(LA‐b‐CL)] as a compatibilizing agent for immiscible poly(vinyl chloride) (PVC) blends with various polymers. These blends possess high thermal performance and toughness. We investigated the effect of P(LA‐b‐CL) as a compatibilizing agent for immiscible PVC blends with poly(ω‐lauryl lactam) [polyamide 12 (PA12)]. We also described the invention of a new compatibilizing agent system involving P(LA‐b‐CL) for PVC/polypropylene (PP) blends. The mechanical and thermal properties of (1) PVC/PA12 blend compatibilized with P(LA‐b‐CL) and (2) PVC/PP blend compatibilized with P(LA‐b‐CL)/PA12/maleic anhydride–modified PP were both enhanced. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1983‐1992, 2004     

Thermostimulative shape memory effect of linear low‐density polyethylene/polypropylene (LLDPE/PP) blends compatibilized by crosslinked LLDPE/PP blend (LLDPE–PP)

A novel linear low‐density polyethylene (LLDPE)/polypropylene (PP) thermostimulative shape memory blends were prepared by melt blending with moderate crosslinked LLDPE/PP blend (LLDPE–PP) as compatibilizer. In this shape memory polymer (SMP) blends, dispersed PP acted as fixed phase whereas continuous LLDPE phase acted as reversible or switch phase. LLDPE–PP improved the compatibility of LLDPE/PP blends as shown in scanning electron microscopic photos. Dynamic mechanical analysis test showed that the melt strengths of the blends were enhanced with increasing LLDPE–PP content. A shape memory mechanism for this type of SMP system was then concluded. It was found that when the blend ratio of LLDPE/PP/LLDPE–PP was 87/13/6, the blend exhibited the best shape memory effect at stretch ratio of 80%, stretch rate of 25 mm/min, and recovery temperature of 135°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Maleic anhydride grafted thermoplastic elastomer as an interfacial modifier for polypropylene/polyamide 6 blends

A maleic anhydride grafted thermoplastic elastomer (TPE_g) was prepared. The effect of the TPE_g on the morphology and performance of polypropylene (PP)/polyamide 6 (PA‐6) blends was studied. The final properties of the blends were tuned through variations in the TPE_g/PA‐6 ratios and TPE_g and PA‐6 percentages in the blends. Scanning electron micrographs showed that the TPE_g greatly improved the homogeneity of the blends, and this led to better mechanical performance. The nonisothermal crystallization behaviors of PP and PA‐6 in the blends, revealed by differential scanning calorimetry, were different from those of pure PP and PA‐6. The crystallization temperature and rate of PP were promoted by the PA‐6 component because of its nucleating effect, whereas stepwise crystallization was detected for PA‐6 in the PP/PA‐6 blends when the TPE_g was added. On the basis of these observations, a schematic model was proposed for these blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1806–1815, 2004     

Influence of PP content on mechanical properties,water absorption,and morphology in PA6/PP blend

PA6/polypropylene (PP) blends are investigated for obtaining balanced strength and toughness. The focus of this study is to understand the effect of PP content on mechanical property, water absorption, impact strength, thermal behavior, and morphology of PP in the absence and presence of PP-g-maleic anhydride compatibilizer. In comparison to pure PA6, all blends have higher impact strength with 161 and 124% increase at 5 wt % PP content in uncompatibilized and compatibilized blends (UB and CB), respectively. Morphology of impact fractured samples shows brittle fracture in the case of CB. scanning electron microscope of cryogenically fractured samples show decrease in domain size and change in shape from ellipsoid to spherical, from UB to CB. Then, 75% reduction in water absorption is observed for 50 wt % PP content UB. Postwater absorption yield strength (YS) remains constant above 10 wt % PP in both UB and CB and decrease in YS is less at higher PP content in CB. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47690.     

Study on isotactic polypropylene/zinc‐neutralized sulfonated ethylene propylene diene monomer rubber/CaCO3 ternary blends

The morphological structure and mechanical properties of isotactic polypropylene (PP)/zinc‐neutralized sulfonated ethylene propylene diene monomer rubber (Zn? SEPDM)/CaCO₃ blends were studied. PP/Zn? SEPDM/CaCO₃ blends were prepared through two different sequences. A: Blending PP with Zn? SEPDM, then adding CaCO₃; B: Blending Zn? SEPDM with CaCO₃, then adding PP. The blending sequence has substantial influence on the mechanical properties. SEM micrographs and X‐ray photoelectron spectrometry indicate that the CaCO₃ filler is encapsulated by Zn? SEPDM in those blends prepared through sequence B, which caused an extra increase of impact strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1635–1640, 2004     

Fractionated crystallization of dispersed PA6 phase of PP/PP‐g‐MAH/PA6 blends

Fractionated crystallization behavior of dispersed PA6 phase in PP/PA6 blends compatibilized with PP‐g‐MAH was investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) in this work. The lack of usual active heterogeneities in the dispersed droplet was the key factor for the fractionated crystallization of PA6. The crystals formed with less efficient nuclei might contain more defects in the crystal structures than those crystallized with the usual active nuclei. The lower the crystallization temperature, the lesser the perfection of the crystals and the lower crystallinity would be. The fractionated crystallization of PP droplets encapsulated by PA6 domains was also observed. The effect of existing PP‐g‐MAH‐g‐PA6 copolymer located at the interface on the fractionated crystallization could not be detected in this work. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3742–3755, 2004     

Compatibilization by main‐chain thermotropic liquid crystalline ionomer of blends of PBT/PP

The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEM and optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends. The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1% LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1110–1117, 2002     

Structure and morphology of an intumescent polypropylene blend

This article deals with the study of the efficiency of different compatibilizing agents in the intumescent polypropylene/polyamide‐6/ammonium polyphosphate (PP/PA‐6/APP) blend. The migration of additive was first investigated by X‐ray photoelectron spectroscopy. The study showed that ethylene–butyl acrylate–maleic anhydride is not efficient in preventing the exudation of APP to the surface. However, ethylene vinyl acetate (EVA) prevented such a phenomenon. Second, the modifications in the blends were analyzed as a function of their compositions. Optical microscopy analysis showed that adding EVA to PP/PA‐6/APP promoted a decrease in the size of PA‐6 droplets. X‐ray diffraction was used to characterize the effect of each component on the PP crystallinity. It was clearly shown that the crystallinity depends on the composition of the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 402–411, 2004     

Effects of dispersed phase composition on thermoplastic polyolefins

Ternary blends of polypropylene (PP), ethylene–octene copolymer (mPE), and high‐density polyethylene (HDPE) were prepared based on the phase behavior and physical properties of mPE/HDPE binary blends, and the results were interpreted in terms of morphology and both rheological and mechanical properties of the ternary blends as well as the binary blends. It was found that when mPE encapsulates HDPE in the PP matrix, compared to the encapsulation of mPE by HDPE, better blend properties were obtained, presumably because of the compatibilizing effect of mPE between PP and HDPE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 179–188, 2004     

Studies on compatibilization of intumescent flame‐retardant/PP composites based on etched PP

The phosphoric acid–pentaerythritol–melamine copolymer was selected as an intumescent flame retardant (IFR). The influence of dicromate acid–etching polypropylene (EPP) on the properties and compatibility of IFR/PP composites was studied. The results obtained from mechanical tests and SEM showed that EPP was a true coupling agent for IFR/PP blends, but without changing the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of EPP was proved by WAXD analysis. Flow tests showed that the flow behavior of composites in the melt is that of a pseudoplastic liquid, which is almost insignificant for EPP affecting the rheological behavior of an IFR/PP composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 522–527, 2002; DOI 10.1002/app.10261     

Crystallization behavior of PP/PP‐g‐MAH/GFR PA66 blends: Establishment of their continuous‐cooling‐transformation of relative crystallinity diagrams

Polypropylene/polypropylene‐grafted‐maleic anhydride/glass fiber reinforced polyamide 66 (PP/PP‐g‐MAH/GFR PA 66) blends‐composites with and without the addition of polypropylene‐grafted‐maleic anhydride (PP‐g‐MAH) were prepared in a twin screw extruder. The effect of the compatibilizer on the thermal properties and crystallization behavior was determined using differential scanning calorimetry analysis. The hold time was set to be equal to 5 min at 290°C. These conditions are necessary to eliminate the thermomechanical history in the molten state. The crystallization under nonisothermal conditions and the plot of Continuous‐Cooling‐Transformation of relative crystallinity diagrams of both PP and PA 66 components proves that PP is significantly affected by the presence of PP‐g‐MAH. From the results it is found that an abrupt change is observed at 2.5 wt % of PP‐g‐MAH as a compatibilizer and then levels off. In these blends, concurrent crystallization behavior was not observed for GFR PA66. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1620–1626, 2007     

Miscibility enhancement of PP/PBT blends with a side‐chain liquid crystalline ionomer

Side‐chain liquid crystalline ionomer (SLCI) containing sulfonic acid groups with a polymethylhydrosiloxane main‐chain was used in the blends of polypropylene (PP) and polybutylene terephthalate (PBT) as a compatibilizer. The crystalline behavior, morphological, and mechanical properties of the blends were investigated in detail by differential scanning calorimetry (DSC), polarizing optical microscope (POM), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Revealed by the shift of T_m in DSC thermogram and the shift of the absorbed peak in FTIR spectra, specific interaction led to stronger interfacial adhesion between these phases, which resulted in much finer dispersion of the minor PBT phase in PP matrix. The SLCI containing sulfonate acid groups acted as physical crosslinking agent along the interface, which compatibilized PP/PBT blends. The mechanical property of the blends including 4 wt % SLCI contents was better than that of other SLCI contents in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of flexibility of ethylene vinyl acetate and crystallization of polypropylene on the mechanical properties of i‐PP/EVA blends

Polymer blend technology has been widely used for the past several years for the modification or enhancement of mechanical properties of polymers to obtain an overall balance of properties over those of the constituents. Despite its interesting mechanical and thermal properties, the impact strength of polypropylene leaves wide scope for improvement. A series of blends of ethylene vinyl acetate (EVA) copolymer with an impact grade of isotactic polypropylene (i‐PP) were prepared by single screw extrusion at 0–0.32 volume fraction of the dispersed phase. The mechanical properties such as tensile behavior, elongation‐at‐break, and impact strength of these blends systems as well as crystallinity were evaluated. Crystallinity data have been used in greater depth to support the mechanical properties. Differential scanning calorimetry studies conducted to study the modification in crystallinity of the crystalline component, i‐PP, of the blend revealed that the rubber component of the blend enhanced the crystallinity of i‐PP phase by providing sites for nucleation. Tensile modulus and strength decreased while the impact strength and breaking elongation enhanced with blending elastomer concentration. The improved properties of these PP/EVA blends are encouraging for carrying out further work on this system (composites) and suggest potential high impact strength applications for PP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012