Dynamic mechanical properties and morphology of polypropylene/maleated polypropylene blends

The dynamic mechanical properties of both homopolypropylene (PPVC)/Maleated Poly-propylene (PP-g-MA) and ethylene-propylene block copolymer (PPSC)/Maleated Poly-propylene (PP-g-MA) blends have been studied by using a dynamic mechanical thermal analyzer (PL-DMTA MKII) over a wide temperature range, covering a frequency zone from 0.3 to 30 Hz. With increasing content of PP-g-MA, α relaxation of both blends gradually shift to a lower temperature and the apparent activation energy ΔE_α increases. In PPVC/PP-g-MA blends, β relaxation shifts to a higher temperature as the content of PP-g-MA increases from 0 to 20 wt % and then change unobviously for further varying content of PP-g-MA from 20 to 35 wt %. On the contrary, in the PPSC/PP-g-MA blends β₁ relaxation, the apparent activation energy ΔE_β1 and β₂ relaxation are almost unchanged with blend composition, while ΔE_β2 increases with an increase of PP-g-MA content. In the composition range studied, storage modulus É value for PPSC/PP-g-MA blends decreases progressively between β₂ and α relaxation with increasing temperature, but in the region the increment for PPVC/PP-g-MA blends is independent of temperature. The flexural properties of PPVC/PP-g-MA blend show more obvious improvement on PP than one of PPSC/PP-g-MA blends. Scanning electron micrographs of fracture surfaces of the blends clearly demonstrate two-phase morphology, viz. the discrete particles homogeneously disperse in the continous phase, the main difference in the morphology between both blends is that the interaction between the particles and the continuous phase is stronger for for PPVC/PP-g-MA than for PPSC/PP-g-MA blend. By the correlation of the morphology with dynamic and mechanical properties of the blends, the variation of the relaxation behavior and mechanical properties with the componenet structure, blend composition, vibration frequency, and as well as the features observed in these variation are reasonably interpreted. © 1996 John Wiley & Sons, Inc.     

Compatibilization effectiveness of maleated polypropylene compared to organoclay in PBT/PP blends

The compatibilization efficiency of a conventional compatibilizer (PP-grafted maleic anhydride) is compared with an organoclay of hydrophilic modifier (Cloisite 30B) in poly(butylene terephthalate)/polypropylene (PBT/PP) immiscible polymer blend. Moreover, the effect of PP-grafted maleic anhydride (PP-g-MA) on localization of Cloisite 30B organoclays is investigated, in this research. Accordingly, PBT/PP blends containing PP-g-MA, organoclay and PP-g-MA/organoclay are prepared by melt mixing method. According to morphological analysis, organoclays are more efficient than PP-g-MA in dispersion and distribution of droplets in PBT/PP blend. Additionally, the size of dispersed-droplets in PBT/PP/organoclay nanocomposite is lower than PBT/PP/PP-g-MA/organoclay sample. From X-ray diffractometry (XRD) and transmission electron microscopy illustrations, it is shown that organoclays represent the higher level of intercalation structure in PBT/PP/organoclay compared to PBT/PP/PP-g-MA/organoclay nanocomposite. PBT/PP/Organoclay nanocomposite indicates higher viscosity and elasticity in comparison with PBT/PP/PP-g-MA/organoclay, as well. The present subject can be explained by the role of PP-g-MA in transferring some parts of organoclays from PBT matrix into PP droplets which hinders the break-up of dispersed-droplets. According to non-linear viscoelastic properties, PBT/PP/organoclay sample shows stronger stress overshoots than PBT/PP/PP-g-MA/organoclay in start-up of shear flow. Modified De Kee-Turcotte model is studied to investigate the yield stress and viscoelastic behavior of different samples. PBT/PP/Organoclay nanocomposite shows higher yield stress compared to PBT/PP blend filled by PP-g-MA/organoclay system.     

Phase behaviors of poly(oxyethylene)-grafted polypropylene copolymers

A family of amphiphilic graft copolymers were prepared from a maleated polypropylene (PP-g-MA) and various crystalline poly(oxyethylene)-segmented amines of 1000 to 3000 molecular weight. Structurally, these copolymers consist of polypropylene (PP) backbone and several crystalline poly(oxyethylene) (POE) pendants in the structure. In the observation of their phase behaviors by using a differential scanning calorimeter (DSC), the interference between the POE segments and PP backbone was found. In a particular case (PP-g-MA/ED-2001), the heat of POE crystallization did not show off in the cooling curve of the DSC, but appeared during the consecutive heating process. Generally, heating and cooling patterns of the DSC analyses showed the shifts of melting and crystallizing temperatures, depending on the length and the termini of POE, from those of the starting materials— PP-g-MA and POE amines. The TGA and optical microscopy observation further supported the DSC analyses.     

Comparing the compatibility of various functionalized polypropylenes with thermoplastic polyurethane (TPU)

Three functionalized polypropylenes (PP), a maleated PP (PP-g-MA), primary amine functionalized PP (PP-g-NH₂), and secondary amine functionalized PP (PP-g-NHR), were melt blended with a thermoplastic polyurethane (TPU) at different compositions. Compatibility of each functionalized PP with TPU was compared by investigating the binary blends using rheological (mixer torques, dynamic shear rheometry), thermal (dynamic mechanical analysis), mechanical (tensile test), and morphological (scanning electron microscopy with image analysis, particle size analysis) measurements. Compatibility of the three functionalized PP's with TPU is ranked in a decreasing order as follows: PP-g-NHR≥PP-g-NH₂?PP-g-MA, which is attributed to higher reactivity of amine (primary and secondary) with urethane linkages. Accordingly, the TPU blends with the two types of amine functionalized PP's exhibited much better synergy, as reflected by much improved mechanical properties including higher tensile strength and ultimate elongation, and finer and more stable morphologies.     

Rheologically determined phase behavior and miscibility of reactively compatibilized poly(ethylene terephthalate)/polypropylene blends

Rheology, phase behavior and morphology of poly(ethylene terephthalate)/polypropylene (PET/PP) blends compatibilized with maleic-anhydrate-grafted-PP (PP-g-MA) and n-butyl-acrylate-glycidyl-methacrylate-ethylene (EBGMA) were studied. According to infrared spectroscopy results, whereas PP-g-MA was merely capable of reacting with hydroxyl groups of PET, epoxy groups of EBGMA could react with both the hydroxyl and carboxyl end groups of PET. The enhanced compatibilizing effect of EBGMA on PET/PP systems over PP-g-MA was also revealed by scanning electron microscopy and mechanical experiments. From frequency and temperature sweep rheological experiments, the dynamic characteristics of the compatibilized blends found to be improved in comparison with those of the uncompatibilized system. Such enhancement was interpreted as a result of the higher miscibility of the compatibilized blends which was further supported by Cole–Cole plot analyses.     

Influence of interfacial adhesion on toughening of polyethylene–octene elastomer/nylon 6 blends

Super-tough nylon 6 was prepared by using polyethylene–octene elastomer (POE) grafted with maleic anhydride as a toughener. The influences of maleating and a compatibilizer on interfacial adhesion and mechanical properties of nylon 6/POE blends were investigated in terms of mechanical testing, Molau tests, SEM observations, IR analyses, and rheological behavior. The results show that the unmodified POE has hardly any contribution to toughness of nylon 6, whereas the maleic anhydride-grafted POE (POE-g-MA) significantly improves the compatibility of POE with nylon 6 and sharply reduces its size in the nylon 6 matrix due to the in situ formation of a graft copolymer between POE-g-MA and nylon 6 during melt processing. With the POE-g-MA, a transition from brittle to ductile occurs. Besides, the use of a compatibilizer in nylon 6/POE-g-MA system shifts the brittle–ductile transition curve to a lower POE-g-MA content, which is attributed, in part, to the chain-extending effect of CE-96 on the nylon 6 matrix leading to further reduction of the sizes of POE-g-MA in the matrix, in part, to the coupling reaction of CE-96 between POE-g-MA and nylon 6. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1711–1718, 1998     

Mechanical and morphological properties of elastomer-modified polypropylene/polyamide-6 blends

Polypropylene/polyamide-6 (70:30) blends, containing dispersed discrete polyamide-6 microphases as matrix reinforcement, represent attractive materials for engineering applications. In order to enhance impact resistance, ethene/propene (EPM) was incorporated as a second separately dispersed microphase using reactive blending technology. Blend morphologies were controlled by adding maleic-anhydride-grafted-polypropylene (PP-g-MA) as compatibilizer during melt processing, thus enhancing dispersion and interfacial adhesion of the polyamide-6 phase. With PP-g-MA volume fractions increasing from 2.5 to 10 vol %, much finer dispersions of discrete polyamide-6 with average domain sizes decreasing from 8 to 0.8 μm were obtained. When polyamide-6 and ethene/propene (EPM)-rubber are dispersed simultaneously in the polypropylene matrix, impact resistance was improved. The influence of PP-g-MA volume fraction and blend morphologies on mechanical properties such as Young's modulus, yield stress, notched Charpy impact resistance was investigated. The ternary polypropylene/polyamide-6/EPM blend properties were compared with those of binary polypropylene blends containing the equivalent volume fraction of EPM. © 1995 John Wiley & Sons, Inc.     

The Effect of Spray-Freeze Drying of Montmorillonite on the Morphology,Dispersion, and Crystallization in Polypropylene Nanocomposites

The spray-freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray-dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD-MMT). Both MMT (used as a reference) and SFD-MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP-g-MA). Polypropylene nanocomposites containing SFD-MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD-MMT particles became even more finer in the presence of PP-g-MA (i.e., in PP/PP-g-MA /SFD-MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD-MMT improved the thermal stability of PP/PP-g-MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation-controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP-g-MA with SFD-MMT. PP/PP-g-MA/SFD-MMT exhibited twice the edge surface energy as compared to PP/PP-g-MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP-g-MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP-g-MA/SFD-MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers     

Dispersion of nanoclay into polypropylene with carbon dioxide in the presence of maleated polypropylene

The effect of maleic anhydride grafted polypropylene (PP-g-MA) on the mechanical and rheological properties of polypropylene (PP)–clay nanocomposites prepared with nanoclay expanded with CO₂ and direct melt blending was studied. The results from the studies of the mechanical properties, rheological properties, and transmission electron microscopy show that when PP-g-MA was combined with the technique that used CO₂, greater enhancements in the mechanical properties and degree of dispersion of nanoclay in PP were observed. Furthermore, yieldlike behavior in the viscosity and a tail in the low-frequency behavior of the elastic modulus was attributed to the reaction of PP-g-MA with the nanoclay surface and not exfoliation. A fairly well-dispersed morphology was observed for concentrations as high 6.8 wt % clay when the clay was expanded and mixed with CO₂. At this concentration, mechanical properties such as yield strength and modulus increased by as much as 13 and 69%, respectively, relative to the pure PP. Furthermore, the modulus of the composite samples prepared with PP-g-MA and CO₂ was some 15% higher than that of samples prepared by direct melt compounding (without the use of CO₂). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of compatibilizer concentration on dynamic rheological behavior and morphology of thermoplastic starch/polypropylene blends

The reactive compatibilization of blends consisting polypropylene (PP) and thermoplastic starch (TPS) (70/30) with different portions of PP-grafted maleic anhydride (PP-g-MA) is carried out by melt mixing. The esterification reaction between the starch hydroxyl and the PP-g-MA groups proved by the FTIR leads to a compatibility improvement. The dynamic rheological properties, morphology, elongation at break, and the impact strength of the blends were studied. The SEM images show that increasing the compatibilizer concentration reduces the dispersed TPS droplet size. The generalized Zener model states that an elastic interface is established (minimum α value) and enables us to predict the dynamic rheological properties of our blends in a longer frequency range to where the current experimental limitation exists. The modified Cross model is implemented to confirm better adhesion between phases when 20 wt % PP-g-MA is used (minimum a_c value). The increase in the dynamic viscoelastic moduli at concentrations up to 20 wt % and the observed plateau at the elongation at break point at this concentration confirmed that this concentration is the optimum for the maximum stress transfer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48742.     

Structure and properties of in situ compatibilized polystyrene/polyolefin elastomer blends

To increase the compatibility of polystyrene (PS) and polyolefin elastomer (POE) blends, a Lewis acid catalyst, aluminum chloride (AlCl₃), was adopted to initiate the Friedel–Crafts alkylation reaction for the formation of PS‐graft‐POE copolymer. Dynamic mechanical analysis indicated that PS/POE and PS/POE/AlCl₃ blends are partially miscible, and the formation of PS‐graft‐POE copolymer increased the compatibility between PS and POE. Scanning electron microscope and transmission electron microscope results showed that the domain size of the blends decreased dramatically and the size distribution became more uniform with the addition of AlCl₃. Such in situ compatibilization also induced hindrance to the macromolecular chain movement, as reflected by the results of the dynamic rheological analysis. The dynamic rheological behaviors of PS/POE and PS/POE/AlCl₃ blends under different temperature showed that in situ compatibilization weakened the effects of thermooxidation on PS/POE blends. Moreover, in situ compatibilization decreased the activation energy of viscous flow and reduced the influence of temperature on PS/POE blends. POLYM. ENG. SCI., 47:951–959, 2007. © 2007 Society of Plastics Engineers     

The Study of Reactively Compatibilized mPPO/PP Blend Systems

Polymer blends of commercial polyphenylene oxide (mPPO) and polypropylene (PP) are immiscible and incompatible in blend system. Maleic anhydride-grafted-copolymer has been employed as in situ compatibilizer for the mPPO and PP blends. This copolymer contains reactive anhydride functional groups that were able to react with mPPO at [sbnd]CH₃ side methyl groups [sbnd]OH terminal groups under the melt conditions. The PP-g-MA copolymer reduces the interfacial tension between the two polymers and act as a bridge between them to make compatible. The blends have been characterized using FTIR, SEM, and its mechanical behavior.     

Aniline-Modified Polypropylene as a Compatibilizer in Polypropylene Carbon Nanotube Composites

Maleic anhydride-grafted polypropylene (PP-g-MA) was reacted with aniline (NH₂C₆H₅) to produce PP-g-NHC₆H₅ and used as a compatibilizer in polypropylene/carbon nanotube composites. Infrared spectroscopy (FTIR) and nuclear magnetic resonance confirmed the reaction between PP-g-MA and aniline. PP-g-NHC₆H₅ resulted a better compatibilizer than PP-g-MA, producing good dispersion and homogeneous distribution of the carbon nanotubes with less agglomerates, as observed by SEM analysis. Improved dispersion and distribution is assumed to be due to the π–π interactions between the –C₆H₅ ring in the prepared compatibilizer and the hexagonal carbon structure in the nanotubes. In addition, a higher degree of crystallinity (12%) was promoted, since it was favored by π–π interactions. This achieved higher crystallinity promoted an increase in tensile modulus, with only slight changes in tensile strength but with an adverse effect on elongation at break.     

Research Advancement in High-Performance Polyamides and Polyamide Blends Loaded with Layered Silicate

Polyamide comprises one of the major classes of polymers. Layered silicates (nanofiller) may enhance properties of polyamide-based hybrids even at very low content. Aliphatic polyamides (nylons) have often been chosen for commercial applications because of excellent physical and chemical properties. Aromatic polyamides (aramids) and aliphatic-aromatic polyamides have been predominantly useful as high-performance materials due to stiffness, low density, and low cost. Recently polyamide blends have become an important route to high-performance materials. Binary blends of polyamide/polypropylene, polyamide/polystyrene, polyamide/polymethyl methacrylate, polyamide/polyurethane, and others have been reported for nanocomposite formation with organoclay. However, ternary blend nanocomposite with nanoclays (PA6/mSEBS, PA6/EPDM-g-MA/H-HDPE) is rarely explored.     

Influence of the compatibilizer/nanoclay ratio on final properties of polypropylene matrix modified with montmorillonite-based organoclay

The use of nanoclays as additives for polymer matrices requires, in some cases (with non-polar matrices) the use of a compatibilizer agent which will act as a bridge or permanent buffer for nanoclay-matrix interaction. In this research, we have worked on the improvement of mechanical and thermal properties of polypropylene matrices by adding montmorillonite based nanoclays (MMT) which have been previously modified with an organic component (a quaternary ammonium salt modifier). In this particular case, we have worked on the optimization of the compatibilizer:nanoclay ratio. As a compatibilizer agent it has been used a propylene graft maleic anhydride copolymer (PP-g-MA) and the PP-g-MA:MMT ratio has varied from 0.25:1 to 4:1. Nanoclay dispersion and intercalation–exfoliation degree has been investigated by X-ray diffraction spectroscopy (XRD) and transmission electron microscopy (TEM). Also, mechanical and thermal properties for different PP-g-MA:MMT ratios have been determined. The results show optimum dispersion and intercalation–exfoliation levels for PP-g-MA:MMT ratios close to 3:1 and 4:1 and also we can observe a slight increase in mechanical and especially in thermal properties for similar ratios.     

Structure and properties of polypropylene-based nanocomposites: Effect of PP-g-MA to organoclay ratio

The structure-property relationships of polypropylene (PP)-based nanocomposites prepared by melt processing have been investigated with a main focus on the ratio of polypropylene grafted with maleic anhydride (PP-g-MA) to organoclay. The morphological observations by transmission electron microscopy and X-ray diffraction are presented in conjunction with the mechanical, rheological and thermal expansion properties of these nanocomposites. Detailed morphological studies and subsequent quantitative particle analyses for the dispersed clay phase reveal that the aspect ratio of clay particles decreases as the amount of clay increases, and it increases as the amount of PP-g-MA increases. The rheological properties suggest that the extent of a percolation network can be enhanced by increasing the number of organoclay particles at a fixed ratio of PP-g-MA to organoclay and by increasing the degree of exfoliation at fixed clay content. However, mechanical and thermal expansion behaviors do not improve correspondingly in all cases because of the reduction of matrix properties by PP-g-MA. The reduction of the modulus and the increase in the expansion of the polymer matrix caused by the presence of PP-g-MA are compared to the prediction of the Chow model. Clearly, the amount of PP-g-MA added along with its lower crystallinity are important factors affecting the mechanical and thermal expansion properties of PP-based nanocomposites.     

Effect of the ratio of maleated polypropylene to organoclay on the structure and properties of TPO-based nanocomposites. Part I: Morphology and mechanical properties

The structure-property relationships of thermoplastic olefin (TPO)-based nanocomposites prepared by melt processing are reported with a main focus on the ratio of maleic anhydride-grafted polypropylene (PP-g-MA) to organoclay. The morphological observations by transmission electron microscopy, atomic force microscopy, and X-ray diffraction are presented in conjunction with the mechanical and rheological properties of these nanocomposites. Detailed quantitative analyses of the dispersed clay particles revealed that the aspect ratio of clay particles decreased as clay content increased but increased as the amount of PP-g-MA increased. Analysis of the elastomer phase revealed that the aspect ratio of the elastomer phase increased in both cases. The presence of clay causes the elastomer particles to become highly elongated in shape and retards the coalescence of the elastomer particles. The modulus and yield strength are enhanced by increasing the PP-g-MA/organoclay ratios. High levels of toughness of the TPO can be maintained when moderate levels of (organoclay) MMT and PP-g-MA are used. The rheological properties suggested that the addition of clay particles and PP-g-MA has a profound influence on the long time stress relaxation of the TPO nanocomposites. Based on these analyses, it is clear that it is important to optimize the ratio of PP-g-MA and organoclay to obtain the desired balance of mechanical properties and processing characteristics for TPO nanocomposites.     

Morphological,thermal, and mechanical properties of polypropylene/polycarbonate blend

This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting glycidyl methacrylate (GMA) onto polypropylene in the molten state. Blend morphologies were controlled by adding PP-g-GMA as compatibilizer during melt processing, thus changing dispersion and interfacial adhesion of the polycarbonate phase. With PP-g-GMA, volume fractions increased from 2.5 to 20, and much finer dispersions of discrete polycarbonate phase with average domain sizes decreased from 35 to 3 μm were obtained. The WAXD spectra showed that the crystal structure of neat PP was different from that in blends. The DSC results suggested that the degree of crystallization of PP in blends decreased as PC content and compatibilizer increased. The mechanical properties significantly changed after addition of PP-g-GMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1857–1863, 1997     

Novel strategy for ternary polymer blend compatibilization

A novel strategy for compatibilization of ternary polymer blends was described. PP (polyolefins)/PA6 (engineering plastics)/PS (styrene polymers) was selected as a model ternary blend system, and the compatibilization effect was investigated by means of SEM, rheometer, dynamic mechanical thermal analysis and mechanical testing. The results indicated that, as a ternary polymer blend compatibilizer, styrene and maleic anhydride dual monomers melt grafted polypropylene [PP-g-(MAH-co-St)] showed more effective compatibilization in the PP/PA6/PS ternary blend system than PP-g-MAH, PP-g-St and their mixture. The good compatibilizing effect of PP-g-(MAH-co-St) can be explained by two mechanisms. One is the in situ formation of [PP-g-(MAH-co-St)]-g-PA6 copolymer at the PP/PA6 interface, and the other is that it also contains styrene blocks, resulting in chemical affinity with PS and PP homopolymers.     

Biodegradation of blends of polyethylene‐octene elastomer with starches by fungi

Five fungi including Aspergillus niger, Penicilium pinophilum, Chaetoomium globsum, Gliocladium virens and Aureobasium pullulans were used to investigate the biodegradation of starch‐based elastomers: polyethylene‐octene elastomer (POE)/starch and grafted POE‐g‐MAH/starch copolymer blends. The viability of the composite spore suspensions were measured before estimating the fungal growth on the surface of specimens. The weight loss, morphology and mechanical properties of the blended specimens were measured using scanning electron microscopy and a mechanical properties tester after 28 days of culturing. The spore suspension in the experiment showed good viability. Pure POE and POE‐g‐MAH did not allow significant fungal growth. Pure POE did not lose weight or have a change in tensile strength, but pure POE‐g‐MAH lost about 0.07% of its weight with a slight reduction in tensile strength during culture period. There was heavy growth on the surface of POE/starch and POE‐g‐MAH/starch blends after 28 days of culturing. The weight loss of POE/starch and POE‐g‐MAH/starch blends increased with increasing starch content. POE‐g‐MAH/starch blends tended to lose more weight than POE/starch blends. After biodegradation, the surface of POE/starch and POE‐g‐MAH/starch blends became rough with many holes and cracks, indicating that the films were eroded by the fungi. Tensile strength of POE/starch and POE‐g‐MAH/starch blends decreased after culturing because of microbial attack. On the contrary, elongation at break of POE‐g‐MAH/starch blends increased after biodegradation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114:3574–3584, 2009