Polymer nanocomposites based on needle‐like sepiolite clays: Effect of functionalized polymers on the dispersion of nanofiller,crystallinity, and mechanical properties

Polypropylene (PP)/sepiolite (Sep) nanocomposites are prepared by melt compounding in a mini‐extruder apparatus. The often used maleic anhydride‐modified polypropylene (PP‐g‐MA) is compared with two custom‐made functionalized polymers, PP‐acid and the di‐block copolymer PP‐PEO, with respect to the filler dispersion and filler reinforcement efficiency. For that purpose, morphological and mechanical studies are carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tensile tests. In addition, the nanocomposites are characterized by wide‐angle X‐ray scattering (WAXS) and differential scanning calorimetric (DSC) techniques, to assess the effect of the nanofiller on the crystalline structure of the PP matrix nano‐filler. The use of PP‐PEO and PP‐acid resulted in a better nanofiller dispersion compared with traditional PP‐g‐MA‐modified systems. Sepiolite acts as nucleating agent for the crystallization of PP and seems to lead to an orientation of the α‐phase crystals. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Plasma treatment‐induced fluorine‐functionalized multi‐walled carbon nanotubes to modify poly(ethylene terephthalate) obtained via in situ polymerization

The introduction of carbon nanotubes in a polymer matrix can markedly improve its mechanical properties and electrical conductivity, and much effort has been devoted to achieve homogeneous dispersions of carbon nanotubes in various polymers. Our group previously performed successfully fluorine‐grafted modification on the sidewalls of multi‐walled carbon nanotubes (MWCNTs), using homemade equipment for CF₄ plasma irradiation. As a continuation of our previous work, in the present study CF₄ plasma‐treated MWCNTs (F‐MWCNTs) were used as a nanofiller with poly(ethylene terephthalate) (PET), which is a practical example of the application of such F‐MWCNTs to prepare polyester/MWCNTs nanocomposites with ideal nanoscale structure and excellent properties. As confirmed from scanning electron microscopy observations, the F‐MWCNTs could easily be homogeneously dispersed in the PET matrix during the in situ polymerization preparation process. It was found that a very low content of F‐MWCNTs dramatically altered the crystallization behavior and mechanical properties of the nanocomposites. For example, a 15 °C increase in crystallization temperature was achieved by adding only 0.01 wt% F‐MWCNTs, implying that the well‐dispersed F‐MWCNTs act as highly effective nucleating agents to initiate PET crystallization at high temperature. Meanwhile, an abnormal phenomenon was found in that the melt point of the nanocomposites is lower than that of the pure PET. The mechanism of the tailoring of the properties of PET resin by incorporation of F‐MWCNTs is discussed, based on structure–property relationships. The good dispersion of the F‐MWCNTs and strong interfacial interaction between matrix and nanofiller are responsible for the improvement in mechanical properties and high nucleating efficiency. The abnormal melting behavior is attributed to the recrystallization transition of PET occurring at the early stage of crystal melting being retarded on incorporation of F‐MWCNTs. Copyright © 2009 Society of Chemical Industry     

Crystallization,mechanical, and fracture behavior of mullite fiber‐reinforced polypropylene nanocomposites

This study describes the reinforcement effect of surface modified mullite fibers on the crystallization, thermal stability, and mechanical properties of polypropylene (PP). The nanocomposites were developed using polypropylene‐grafted‐maleic anhydride (PP‐g‐MA) as compatibilizer with different weight ratios (0.5, 1.0, 1.5, 2.5, 5.0, and 10.0 wt %) of amine functionalized mullite fibers (AMUF) via solution blending method. Chemical grafting of AMUF with PP‐g‐MA resulted in enhanced filler dispersion in the polymer as well as effective filler‐polymer interactions. The dispersion of nanofiller in the polymer matrix was identified using scanning electron microscopy (SEM) elemental mapping and transmission electron microscopy (TEM) analysis. AMUF increased the Young's modulus of PP in the nanocomposites up to a 5 wt % filler content, however, at 10 wt % loading, a decrease in the modulus resulted due to agglomeration of AMUF. The impact strength of PP increased simultaneously with the modulus as a function of AMUF content (up to 5 wt %). The mechanical properties of PP‐AMUF nanocomposites exhibited improved thermal performance as compared to pure PP matrix, thus, confirming the overall potential of the generated composites for a variety of structural applications. The mechanical properties of 5 wt % of AMUF filled PP nanocomposite were also compared with PP nanocomposites generated with unmodified MUF and the results confirmed superior mechanical properties on incorporation of modified filler. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43725.     

Calcium carbonate (CaCO3) nanoparticle filled polypropylene: Effect of particle surface treatment on mechanical,thermal, and morphological performance of composites

The present study was aimed to see the effect of surface treatment on nanocomposites with different fatty acids (stearic acid and oleic acid) having two different coupling agents (titanate and silane). Nanocomposites were prepared via melt mixing in Haake 90 twin screw extruder. The characterization of nanocomposites had been carried out using various advance analytical techniques such as dynamic mechanical analysis, thermogravimetric analysis, heat distortion temperature, melt flow index, and scanning electron microscopy. The strength and stiffness were also improved with the incorporation of maleic‐anhydride grafted ethylene propylene rubber in PP/Nano‐CaCO₃ nanocomposites. The tensile, flexural, and impact strength properties of PP/MA‐g‐EPR/treated‐CaCO₃ and untreated nanocomposites were determined. These studies revealed that stearic acid treated nanofiller filled composites had better properties than those of untreated and oleic acid treated nanofiller filled composites. The SEM studies demonstrated that the dispersion and distribution of Nano‐CaCO₃ (nCaCO₃) particles within the polypropylene matrix were dependent on the nature of surface treating agents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polypropylene/nTiO2 nanocomposites using melt mixing and its investigation on mechanical and thermal properties

This study investigates the preparation of nTiO₂ particle using green chemistry approach and its subsequent effect on the properties of isotactic polypropylene (iPP) nanocomposites, which is one of the most suited thermoplastic polymer. The nanocomposite of iPP with TiO₂ nanoparticle (0.5, 1, 1.5, 2, and 2.5 wt%) were prepared on Brabender plasticorder, which was then subjected to injection molding to get a dumbbell‐shape specimens. Meanwhile, TiO2 nanoparticles (nTiO₂) were prepared using ultrasonic cavitation technique using leaf extract of Murraya koenigii . The extraction of leaf was carried out using distilled water as a solvent. The size and shape of nTiO₂ particle was confirmed using transmission electron microscope and found to be spherical shape of diameter ∼10–45 nm. The mechanical properties of nTiO₂ reinforced iPP composites were studied using universal testing machine. Moreover, thermal properties were studied using Vicat softening temperature, thermogravimetric analyzer, and differential scanning calorimeter. The extent of dispersion of nTiO₂ in iPP matrix was studied using field‐emission scanning electron microscope and X‐ray diffractometer. The mechanical and thermal properties of nTiO₂‐iPP composites were found to be improved significantly with increasing amount of nTiO₂ particles except elongation at break, which is a marginal increment. This improvement in properties (mechanical and thermal) was due to the uniform dispersion of nTiO₂ in iPP matrix, which means that chains of polymers were well adhered with the spherical shaper particles. POLYM. COMPOS., 38:1273–1279, 2017. © 2015 Society of Plastics Engineers     

Property improvement of plasticized poly(vinyl chloride) by nano‐TiO2 and poly(methyl methacrylate)–encapsulated nano‐TiO2

To improve the physical properties of plasticized poly(vinyl chloride) (p‐PVC), the p‐PVC nanocomposites filled with four loading levels (3, 5, 7, and 9 parts per hundred of PVC resin) of either nanosized titanium dioxide (nTiO₂) or poly(methyl methacrylate)–encapsulated nTiO₂ (PMMA‐nTiO₂) were prepared by melt mixing on a two‐roll mill, followed by compression molding. The PMMA‐nTiO₂ used in this study was synthesized via in situ differential microemulsion polymerization. The resulting PMMA‐nTiO₂ exhibited core‐shell morphology (nTiO₂ core and PMMA shell) with an average diameter of 42.6 nm. The effects of nTiO₂ and PMMA‐nTiO₂ on the tensile properties, hardness, morphology, and thermal stability of the as‐prepared p‐PVC nanocomposites were then investigated and compared. The inclusion of either nTiO₂ or PMMA‐nTiO₂ nanoparticles increased the tensile strength, Young's modulus, hardness, and thermal stability of the nanocomposites in a dose‐dependent manner and reduced the elongation at break. However, the elongation at break was still higher than that for the neat p‐PVC. Moreover, the PMMA‐nTiO₂ nanocomposites had a higher enhancement of the tensile strength, Young's modulus, hardness, and thermal stability than the nTiO₂ nanocomposites at a similar loading level. Hence, the PMMA grafted on the nTiO₂ surface played an important role in toughening and increasing the thermal stability of the nanocomposites owing to the improved miscibility and interfacial adhesion between the encapsulated nanofiller and PVC matrix. J. VINYL ADDIT. TECHNOL., 22:433–440, 2016. © 2015 Society of Plastics Engineers     

The physical and mechanical properties of beta‐nucleated polypropylene/montmorillonite nanocomposites

Polypropylene (PP) and polypropylene/polypropylene‐g‐maleic anhydride/ organomontmorillonite (PP/PP‐g‐MA/OMMT) nanocomposites were modified with 0.05 to 0.3% (w/w) of the aryl amide β‐nucleator to promote the formation of hexagonal crystal modification (β‐phase) during melt crystallization. The nonisothermal crystallization behavior of PP, PP/PP‐g‐MA/OMMT and β‐nucleated PP/PP‐g‐MA/OMMT nanocomposites were studied by means of differential scanning calorimetry. Structure‐property relationships of the PP nanocomposites prepared by melt compounding were mainly focused on the effect and quantity of the aryl amide nucleator. The morphological observations, obtained from scanning electron microscopy, transmission electron microscopy and X‐ray diffraction analyses are presented in conjunction with the thermal, rheological, and mechanical properties of these nanocomposites. Chemical interactions in the nanocomposites were observed by FT‐IR. It was found that the β‐crystal modification affected the thermal and mechanical properties of PP and PP/PP‐g‐MA/OMMT nanocomposites, while the PP/PP‐g‐MA/OMMT nanocomposites of the study gained both a higher impact strength (50%) and flexural modulus (30%) compared to that of the neat PP. β‐nucleation of the PP/PP‐g‐MA/OMMT nanocomposites provided a slight reduction in density and some 207% improvement in the very low tensile elongation at break at 92% beta nucleation. The crystallization peak temperature (T_cp) of the PP/PP‐g‐MA/OMMT nanocomposite was slightly higher (116°C) than the neat PP (113°C), whereas the β‐nucleation increased the crystallization temperature of the PP/PP‐g‐MA/OMMT/aryl amide to 128°C, which is of great advantage in a commercial‐scale mold processing of the nanocomposites with the resulting lower cycle times. The beta nucleation of PP nanocomposites can thus be optimized to obtain a better balance between thermal and mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Effect of hydrothermally synthesized titanium nanotubes on the behaviour of polypropylene for antimicrobial applications

TiO₂ nanotubes (TiO₂‐Ntbs) synthesized by a hydrothermal method were used as filler to prepare polypropylene (PP) composites by melt blending. Their structural properties as well as their biocidal potential were studied. Nanotubes were used either as‐synthesized or organically modified with hexadecyltrimethoxysilane (Mod‐TiO₂). These nanoparticles form secondary structures with sizes around 100 nm that are well dispersed in the polymer matrix, but not homogeneously because agglomerates larger than 1 µm are also seen by transmission electron microscopy. Regarding the properties of the composites, the incorporation of the nanoparticles increased the polymer's crystallinity and thermal stability. The maximum decomposition temperature of the matrix increased by ca 13 °C compared to virgin PP. The nanotubes further increase the spherulite nucleation density, and therefore a reduction in the diameter of spherulites and an increase in their number were observed. Despite the above, the addition of TiO₂ nanoparticles did not modify the mechanical properties of PP. The PP/TiO₂‐Ntb nanocomposites exposed to UVA radiation showed a biocidal behaviour, reducing a colony of Escherichia coli by 81%. © 2015 Society of Chemical Industry     

Effects of nanoparticle treatment on the crystallization behavior and mechanical properties of polypropylene/calcium carbonate nanocomposites

Effects of nanoparticle surface treatment on the crystallization behavior and mechanical properties of polypropylene (PP)/CaCO₃ nanocomposites were investigated by using differential scanning calorimetry (DSC), polarized optical microscope (POM), X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results demonstrated that the interfacial interaction formed between PP and nanoparticles significantly influenced the thermal and mechanical properties of nanocomposites. It was found that CaCO₃ nanoparticles modified by a single aluminate coupling agent (CA‐1) could improve the onset crystallization temperature more effectively than that modified by a compound surface‐treating agent (CA‐2) could. However, there is no significant difference in total rate of crystallization for the two PP/CaCO₃ nanocomposites (PPC‐1 and PPC‐2), which contained CA‐1 and CA‐2, respectively. In contrast, CA‐2 modified nanoparticles could cause smaller spherulites and induce much more β‐phase crystal in nanocomposites than that of CA‐1 modified nanoparticles. This may be explained by a synergistic effect of aluminate coupling agent and stearic acid in CA‐2, which also resulted in an improved toughness for PPC‐2. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 3480–3488, 2006     

The comparison of the behaviors of polymer/clay nanocomposites based on high density polyethylene and polypropylene in exposure of electron‐irradiation

The effect of irradiation on thermal and mechanical properties of high density polyethylene (HDPE) and polypropylene (PP)/clay nanocomposites in the presence of polyethylene glycol (PEG) and polypropylene glycol (PPG) for enhancing the clay dispersion into the polymer matrices is considered. The morphology studies show that clay layers satisfactorily expand in the presence of compatibilizers. The irradiation improves the mechanical properties of HDPE nanocomposites at 500 kGy, but it decreases the tensile strength of PP nanocomposites. The addition of PEG markedly ameliorates the mechanical properties of HDPE nanocomposites at 500 kGy, while this improvement is not deduced for PP nanocomposites. The thermogravimetric analysis data show that the irradiation increases the thermal stability of HDPE nanocomposites at the clay content of 5 wt% with and without compatibilizer. The thermal stability of PP nanocomposites descends with the irradiation dose, and the presence of PPG into the PP matrix intensifies this reduction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

The effect of UV irradiation on the electrospun PCL/TiO2 composites fibers

The effect of UV irradiation and micro‐ and nano‐TiO₂ as well as titanate nanotubes (TiNT) on the phase morphology and thermal properties of the electrospun PCL composite fibers was investigated. Polycaprolactone (PCL)/TiO₂ (micro‐ and nano‐TiO₂ as well as titanate nanotubes) composite fibers were prepared by electrospinning a polymer solution. The PCL and PCL/TiO₂ composite fibers were exposed to UV light at irradiation times of 5 and 10 days. After UV irradiation the crystallinity of the electrospun PCL/TiNTcomposite fibers increased because of the large specific surface area of TiNT. The thermal stability of the PCL/TiNT electrospun composite fibers increased due to the formation of crosslinking structure after UV irradiation. The SEM analysis suggests that after UV radiation the fibers showed high degree of degradation due to the high number of fibers breakages and fibers surface voids. The results of FTIR spectroscopy confirmed that the TiO₂ particles enhance the degradation process because of their photocatalytic activity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43539.     

Influences of polypropylene grafted to SiO<Subscript>2</Subscript> nanoparticles on the crystallization behavior and mechanical properties of polypropylene/SiO<Subscript>2</Subscript> nanocomposites

Influences of polypropylene (PP) grafted to SiO₂ nanoparticles (7 nm) were studied on the crystallization behavior and the mechanical properties of PP/SiO₂ nanocomposites. PP for the matrix and grafting was synthesized in order to have an identical primary structure, aiming at their co-crystallization and resulting reinforcement of filler-matrix interfaces. The grafted PP chains improved the dispersion of SiO₂, and notably accelerated nucleation in crystallization. It was plausible that the grafted chains whose one chain end was pinned to SiO₂ became nuclei of the crystallization (co-crystallization between the matrix and grafted chains), thus directly bridging between the matrix and SiO₂ nanoparticles. The Young’s modulus and tensile strength were most improved by the grafted PP chains at low filler contents such as 2.3 wt%, whose origin was attributed to effective load transfer to SiO₂ through the co-crystallization-mediated bridging.     

Advance polymeric carbon nanocomposite films with enhanced thermo‐mechanical properties

The homogenous nanocomposite films of UV/O₃ oxidized multiwall carbon nanotubes (MWCNTs) subsequently modified with aniline moiety were synthesized with polymethylmethacrylate (PMMA) through free radical polymerization. The phenylamine functional groups present on the surface of MWCNTs providing an anchoring sites for deposition of Ag metal nanoparticles (NP).The in situ free radical polymerization of MMA in the presence of these well dispersed nanotubes gave a new class of radiation resistant nanocomposite films. The synthesized materials were characterized by FT‐IR, TGA, TEM, EDX, TC, DMA, universal testing machine, and optical microscopy to ascertain their structural morphologies, thermal stability, and mechanical strength. The microscopic and structural properties reflect the homogenous mixing of modified MWCNTs in polymer matrix contributing in enhancement of thermal stability, thermo‐mechanical strength, glass transition temperatures, and thermal conductivity of nanocomposites even at 0.25 wt% addition of modified nanofiller. Thermal and thermo‐mechanical behavior of pre‐ and post‐UV/O₃ irradiated nanocomposite films have been compared with neat polymer. The results revealed that modified nanofiller network can effectively disperse the radiation and has a dramatic reinforcement effect on the nature of degradation of PMMA matrix. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Structural and mechanical properties of polystyrene nanocomposites with 1D titanate nanostructures prepared by an extrusion process

Polystyrene (PS) nanocomposites with titanate nanotubes and titanate nanoribbons were prepared by an extrusion process at 180°C. Nanocomposites with 1 wt% of nanofillers and pure PS that had also been exposed to the extrusion process were comparatively examined with scanning electron microscopy (SEM), electron dispersive X‐ray spectrometry (EDS) mapping, solid state proton nuclear magnetic resonance measurements (¹H NMR), tensile tests, and shear creep measurements. SEM images and EDS mapping analysis show that titanate nanoribbons homogeneously distribute at a micrometer length‐scale in the PS matrix during the extrusion process. This is not the case for titanate nanotubes, which show a stronger tendency to form clusters. Solid state ¹H NMR studies, however, proved that the nanocomposites are inhomogeneous at a nanometric scale where structural components with highly mobile PS molecules coexist with domains of rigid PS molecules. Differences in the ¹H spin‐lattice relaxation at and above the glass transition temperature T_g = 373 K suggest that nanofillers affect the thermodynamic properties of nanocomposite domains. Only a slight increase in mechanical tensile properties was observed in the case of the nanocomposite containing 1 wt% of titanate nanoribbons (TiNRs) probably reflecting a weak interaction between the polymer matrix and the nanofiller. Nevertheless, our results prove that the use of functionalized TiNRs may, in combination with the extrusion process, represent a very promising starting point for the preparation of TiNR nanocomposites at the industrial level. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation and Characterization of Polypropylene Nanocomposites Filled with Nano Calcium Phosphate

The synthesized nano calcium phosphate by matrix mediated growth and controlled technique was used as nanofiller in the preparation of polypropylene nanocomposites. Nanocomposites with different filler concentrations were prepared. The content of nano calcium phosphate was varied from 1 to 3 wt% in the preparation of PP nanocomposites. During preparation of nanocomposites shear rate was varied by means of increase in rpm, i.e., 60, 70, 80 and 90 with the help of Brabender Plastograph and the effect of shear rate was studied with respective to mechanical and thermal properties of composites. The comprehensive evaluation of the PP nanocomposites filled with nano calcium phosphate was done to observe the substantial improvement in the performance properties. The mechanical and thermal properties were determined by Universal Testing Machine (UTM) and Thermogravimetric Analyzer (TGA), respectively. The morphology of the fracture surfaces of the prepared PP nanocomposites filled with nano calcium phosphate was studied by Scanning Electron Microscopy (SEM).     

Investigation on flame retardancy and rheological and thermomechanical characterisation of multiwall carbon nanotube reinforced nanocomposites

Abstract

In the present work, the influence of multiwalled carbon nanotubes (MWCNTs) on the flame retardancy and rheological, thermal and mechanical properties of polybutilen terephthalate (PBT) and polypropylene (PP) matrixes has been investigated. The carbon nanotube content in the thermoplastic materials was 2 and 5?wt‐%. The nanocomposites were obtained by diluting a masterbatch containing 20?wt‐% nanotubes using a twin‐screw extruder and the thermal properties were analysed by differential scanning calorimetry and thermogravimetric analysis; thermomechanical properties were determined by dynamic mechanical thermal analysis and the rheological behaviour was studied by a Thermo Haake Microcompounder. The results concerning the flame retardancy show that the MWCNTs are not equally effective as flame retardants in PP and PBT. The ignition time is increased only for PBT whereas the extinguishing time is decreased for PP and PBT. The reinforcement of the thermoplastics with multiwall carbon nanotubes is improved regarding the mechanical and thermal properties of the nanocomposites compared to pristine materials and the behaviour of thermoplastic nanocomposites regarding fire retardancy depends on the nature of the polymeric matrix.     

Interfacial influence on mechanical properties of polypropylene/polypropylene‐grafted silica nanocomposites

Three types of polypropylene‐grafted silica (PGS‐2 K, PGS‐8 K and PGS‐30 K) with different grafting chain lengths were prepared. After melt‐blending PGS with polypropylene (PP), we studied the PP/PGS interface properties and the influence of PP/PGS interfaces on mechanical properties of nanocomposites. The strong matrix/particle interface was observed in PP/PGS‐30 K nanocomposites with 5 wt % particle loading as evidenced by 2.5 °C increased glass transition temperature (T_g) compared with neat PP, whereas the weak matrix/particle interface was observed in PP/PGS‐2 K nanocomposites with decreased T_g. The variations in the matrix/particle interfacial strength lead to a transition in the yield stress of nanocomposites. Compared with the unfilled PP, the yield stress of the PP/PGS‐2 K nanocomposites is decreased by 0.7 MPa, and the yield stress of the PP/PGS‐30 K nanocomposites is enhanced by 1.4 MPa. In addition, benefiting from good dispersion, the PP/PGS‐masterbatch nanocomposites with a strong matrix/particle interface not only exhibit increased Young's modulus and yield stress, but also the strain at break remains in line with the unfilled PP, which is in contrast to the conventional wisdom that the gain in modulus and strength must be at the expense of the decreased break strain. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45887.     

Evaluation of amine functionalized polypropylenes as compatibilizers for polypropylene nanocomposites

The compatibilization effects provided by amine functionalized polypropylenes versus those of a maleated polypropylene, PP-g-MA, for forming polypropylene-based nanocomposites were compared. Amine functionalized polypropylenes were prepared by reaction of maleated polypropylene, PP-g-MA, with 1,12-diaminododecane in the melt to form PP-g-NH₂ which was subsequently protonated to form PP-g-NH₃⁺. Nanocomposites were prepared by melt processing using a DSM microcompounder (residence time of 10 min) by blending polypropylene and these functionalized materials with sodium montmorillonite, Na-MMT, and with an organoclay. X-ray and transmission electron microscopy plus tensile modulus tests were used to characterize those nanocomposites. Composites based on Na-MMT as the filler showed almost no improvement of tensile modulus compared to the polymer matrix using any of these functionalized polypropylenes, which indicated that almost no exfoliation was achieved. All the compatibilized nanocomposites using an organoclay, based on quaternary ammonium surfactant modified MMT, as the filler had better clay exfoliation compared to the uncompatibilized PP nanocomposites. Binary and ternary nanocomposites using amine functionalized polypropylenes had good clay exfoliation, but no advantage over those using PP-g-MA. The PP-g-MA/organoclay and PP/PP-g-MA/organoclay nanocomposites showed the most substantial improvements in terms of both mechanical properties and clay exfoliation.     

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins

Effect of silica nanofiller on the deformation response and morphology of low‐ and high‐density polyethylene (HDPE, LDPE) and isotactic polypropylene (PP) modified with fumed silica was investigated. The dynamic‐mechanical thermal spectroscopy, differential scanning calorimetry, optical microscopy, and density measurements were carried out to determine the temperature dependence of storage and loss moduli as well as nanocomposite morphology. It was demonstrated that the degree of matrix reinforcement is considerably affected by the extent of matrix crystallinity, especially, in the temperature range from (T_m–130°C) to T_m. Based on experimental evidence and literature review, it is proposed that this phenomenon may be attributed to the alpha‐mechanical relaxation process occurring above matrix T_g. As a result of adding silica into the melted matrix, mobility of chains in contact with silica particles became reduced. This caused substantial changes in morphology of these semicrystalline nanocomposites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

SBS nanocomposites as toughening agent for polypropylene

The toughening of polypropylene [PP] with styrene–butadiene–styrene rubber [SBS]/montmorillonite [MMT] nanocomposites was investigated with respect to morphological, thermal, and mechanical properties. The MMT/SBS nanocomposites were prepared in an internal mixer, using an epoxidized SBS [SBSe] to investigate its effect as a compatibilizer. The MMT/SBS nanocomposite was added to PP up to 10 wt%, aiming at material toughening. Transmission electron microscopy (TEM) revealed MMT induced dispersed-phase reductions when compared to typical PP/SBS blends. In addition, changes in the PP crystallization process were observed in the presence of the nanocomposite. Surprisingly, the use of nanofiller, combined with SBSe compatibilizer agent, increased the PP impact strength by about 60%, with no reduction in the tensile module.