Graphene/poly(styrene‐b‐isoprene‐b‐styrene) nanocomposite optical actuators

This article presents an optomechanical actuator, which is driven by infra red (IR) radiation. The actuator is a nanocomposite‐containing graphene platelets embedded in poly(styrene‐b‐isoprene‐b‐styrene) (SIS) matrix. 0.1 mm thick free‐standing nanocomposite films are fabricated by a simple process of solvent casting. We demonstrate that graphene/SIS nanocomposite contracts on irradiation with IR radiation under strained conditions, whereas expansion behavior was exhibited by them when no prestrain is applied. A maximum photomechanical stress of 28.34 kPa and strain upto 3.1% was obtained for these nanocomposite actuators. We have also studied the mechanical characteristics and thermal degradation of these nanocomposite actuators. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3902–3908, 2013     

Preparation and characterization of poly(styrene‐b‐butadiene‐b‐styrene)/montmorillonite nanocomposites

With some polymerizable small molecules grafting onto the montmorillonite surface, we disposed the clay through in‐situ emulsion polymerization, and the structure of the modified montmorillonites were studied through Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The nanocomposites of poly(styrene‐b‐butadiene‐b‐styrene) (SBS)/montmorillonite with excellent mechanical properties were prepared by mixing SBS and the modified montmorillonite on the double rollers at 150°C. The exfoliation of the layered silicates was confirmed by XRD analysis and transmission electron microscopy (TEM) observation. After mechanical kneading of the molten nanocomposites, the exfoliation structure of the silicates is still stable for polystyrene macromolecules grafting onto the silicates. Upon the addition of the modified montmorillonite, the tensile strength, elongation at break and tear strength of the nanocomposites increased from 22.6 MPa to 31.1 MPa, from 608% to 948%, from 45.32 N/mm to 55.27 N/mm, respectively. The low‐temperature point of glass‐transition temperature (T_g) of the products was about −77°C, almost constant, but the high‐temperature point increased from 97°C to 106°C. In addition, the nanocomposites of SBS and modified montmorillonites showed good resistance to thermal oxidation and aging. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Mechanical and piezo‐resistive properties of styrene–butadiene–styrene copolymer covalently modified with graphene/styrene–butadiene–styrene composites

As novel piezoelectric materials, carbon‐reinforced polymer composites exhibit excellent piezoelectric properties and flexibility. In this study, we used a styrene–butadiene–styrene triblock copolymer covalently grafted with graphene (SBS‐g‐RGO) to prepare SBS‐g‐RGO/styrene–butadiene–styrene (SBS) composites to enhance the organic solubility of graphene sheets and its dispersion in composites. Once exfoliated from natural graphite, graphene oxide was chemically modified with 1,6‐hexanediamine to functionalize with amino groups (GO–NH₂), and this was followed by reduction with hydrazine [amine‐functionalized graphene oxide (RGO–NH₂)]. SBS‐g‐RGO was finally obtained by the reaction of RGO–NH₂ and maleic anhydride grafted SBS. After that, X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and other methods were applied to characterize SBS‐g‐RGO. The results indicate that the SBS molecules were grafted onto the graphene sheets by covalent bonds, and SBS‐g‐RGO was dispersed well. In addition, the mechanical and electrical conductivity properties of the SBS‐g‐RGO/SBS composites showed significant improvements because of the excellent interfacial interactions and homogeneous dispersion of SBS‐g‐RGO in SBS. Moreover, the composites exhibited remarkable piezo resistivity under vertical compression and great repeatability after 10 compression cycles; thus, the composites have the potential to be applied in sensor production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46568.     

Preparation and characterization of PS‐PMMA/ZnO nanocomposite films with novel properties of high transparency and UV‐shielding capacity

High transparent and UV‐shielding poly (styrene)‐co‐poly(methyl methacrylate) (PS‐PMMA)/zinc oxide (ZnO) optical nanocomposite films were prepared by solution mixing using methyl ethyl ketone (MEK) as a cosolvent. The films were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis) spectra, high‐resolution transmission electron microscopy (HR‐TEM), and atomic force microscope (AFM). Cross‐section HR‐TEM and AFM images showed that the ZnO nanoparticles were uniformly dispersed in the polymer matrix at the nanoscale level. The XRD and FTIR studies indicate that there is no chemical bond or interaction between PS‐PMMA and ZnO nanoparticles in the nanocomposite films. The UV–vis spectra in the wavelength range of 200–800 nm showed that nanocomposite films with ZnO particle contents from 1 to 20 wt % had strong absorption in UV spectrum region and the same transparency as pure PMMA‐PS film in the visible region. The optical properties of polymer are greatly improved by the incorporation of ZnO nanoparticles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Tailored dielectric and mechanical properties of noncovalently functionalized carbon nanotube/poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) nanocomposites

The preparation of high‐dielectric poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) composites containing functionalized single‐walled carbon nanotubes (f‐SWCNTs) noncovalently appended with dibutyltindilaurate are reported herein. Transmission electron microscopy and X‐ray photoelectron and Raman spectroscopy confirmed the noncovalent functionalization of the SWCNTs. The SEBS‐f‐SWCNT composites exhibited enhanced mechanical properties as well as a stable and high dielectric constant of approximately 1000 at 1 Hz with rather low dielectric loss at 2 wt% filler content. The significantly enhanced dielectric property originates from the noncovalent functionalization of the SWCNTs that ensures good dispersion of the f‐SWCNTs in the polymer matrix. The f‐SWCNTs also acted as a reinforcing filler, thereby enhancing the mechanical properties of the composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and structure and mechanical properties of poly(styrene‐b‐butadiene)/clay nanocomposites

Star‐shaped and linear block thermoplastic poly(styrene‐b‐butadiene) copolymer (SBS)/organophilic montmorillonite clays (OMMT) were prepared by a solution approach. The intercalation spacing in the nanocomposites and the degree of dispersion of nanocomposites were investigated by X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The mechanical properties, dynamic mechanical properties, and thermal stability of these nanocomposites were determined. Results showed that SBS chains were well intercalated into the clay galleries and an intercalated nanocomposite was obtained. The mechanical strength of nanocomposites with the star‐shaped SBS/OMMT were significantly increased. The addition of OMMT also gave an increase of the elongation, the dynamic storage modulus, the dynamic loss modulus, and the thermal stability of nanocomposites. The increase of the elongation of nanocomposites indicates that SBS has retained good elasticity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3430–3434, 2004     

Convenient approach to making nanocomposites based on a chitosan–poly(vinyl pyrrolidone) polymer matrix and a graphene nanofiller

Conducting, mechanically durable, elastic nanocomposite films were prepared with chitosan (CS) as the polymer matrix, graphene obtained from highly exfoliated graphite as the nanofiller, and poly(vinyl pyrrolidone) (PVP) as the stabilizer of the graphene sheets. The maximum graphene content in the composites without a loss of uniformity and other useful properties increased up to 4.0 wt %. The resulting composites were characterized by scanning electron microscopy, Raman spectroscopy, X‐ray diffraction analysis, mechanical testing, and electrical conductivity testing to determine the effects of the addition of graphene on the morphology and mechanical and electrical properties of the CS–PVP–graphene nanocomposite films. In this study, we took an approach to making nanocomposites from the perspectives of green chemistry, environmental protection, regenerative medicine, and low cost. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45038.     

Morphology,mechanical properties and electromagnetic shielding effectiveness of poly(styrene‐b‐ethylene‐ran‐butylene‐b‐styrene)/carbon nanotube nanocomposites: effects of maleic anhydride,carbon nanotube loading and processing method

Nanocomposites based on poly(styrene‐b‐ethylene‐ran‐butylene‐b‐styrene) (SEBS) and carbon nanotubes (CNTs) (SEBS/CNT) as well as SEBS grafted with maleic anhydride (SEBS‐MA)/CNT were successfully prepared for electromagnetic shielding applications. Both SEBS/CNT and SEBS‐MA/CNT nanocomposites were prepared by melt compounding and were post‐processed using two different techniques: tape extrusion and compression moulding. The different nanocomposites were characterized by Raman spectroscopy and rheological analysis. Their mechanical properties, electrical properties (10^-2–10⁵ Hz) and electromagnetic shielding effectiveness (8.2–12.4 GHz) were also evaluated. The results showed that the CNT loading amount, the presence of MA in the matrix and the shaping technique used strongly influence the final morphologies and properties of the nanocomposites. Whilst the nanocomposite containing 8 wt% CNTs prepared by compression moulding presented the highest electromagnetic shielding effectiveness (with a value of 56.73 dB, which corresponds to an attenuation of 99.9996% of the incident radiation), the nanocomposite containing 5 wt% CNTs prepared by tape extrusion presented the best balance between electromagnetic and mechanical properties and was a good candidate to be used as an efficient flexible electromagnetic interference shielding material. © 2018 Society of Chemical Industry     

Surface microphase separation in PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films

Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structural and ordering behavior of lamellar polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer containing layered silicates

Nanocomposites based on organically modified montmorillonites (OMMTs) and sodium montmorillonite (CLO‐Na⁺) with poly(styrene‐b‐butadiene‐b‐styrene) (SBS) diblock copolymer have been investigated. Solution blending of OMMT suspension in toluene with SBS and subsequent static casting and annealing resulted in transparent films. Final samples were processed by compression molding. The intercalation spacing in the nanocomposites, microphase separation of the SBS, and the degree of dispersion of nanocomposites were investigated by X‐ray diffraction (Wide and small‐angle X‐ray scattering), transmission optical microscopy (TOM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The increase of basal spacing of OMMT in the nanocomposites suggested the intercalation of SBS. The lamellar structure perfection was extensively affected by both OMMT. AFM images and TOM micrographs only showed well dispersed but not exfoliated nanocomposites. On the other hand, TEM showed inserted tactoids into both blocks depending on the surfactant used (stained samples) and the dispersion of those tactoids (unstained samples). Fourier transform infrared spectroscopy indicated only the presence of the OMMT into the SBS. Deviations of the decomposition pathway of pristine SBS with addition of the OMMT were found by thermogravimetric analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influences of dicumyl peroxide on morphology and mechanical properties of polypropylene/poly(styrene‐b‐butadiene‐b‐styrene) blends via vane‐extruder

Polypropylene (PP) and poly(styrene‐b‐butadiene‐b‐styrene) block copolymer (SBS) were melt‐blended in the presence of initiator system. Dicumyl peroxide (DCP)/Triallyl isocyanurate (TAIC) via self‐deigned VE, aiming at in situ reactive compatibilization of toughed PP/SBS blend. The reactivity, morphology and mechanical properties of PP/SBS/DCP/TAIC blends were studied. Online torque detection was conducted to monitor changes in viscosities of reactive compatibilized blends, which could give proof of the interfacial grafted reaction induced by DCP/TAIC system. The effect of reactive compatibilization on the dispersed particles sizes and interfacial adhesion was studied by scanning electron microscopy. Analysis on mechanical performance revealed the impact strength improved after treated by initiator system, moreover, the impact‐fractured surface observation showed, the failure mode changed from debonding mechanism of neat 50PP/50SBS blend to plastic deformation mechanism of blend containing 3.0 phr initiator system. With improved interfacial adhesion, compatibilized blends not only were toughened but also exhibited enhanced tensile strength and thermal stability. Dynamic mechanical analysis showed a reduction of between PP phase and the PB segments in SBS phase, indicating reactive compatibilization of the blend was achieved. In the final part, a brief discussion was given about the dominant effects from chain scission of PP matrix to intergrafting reactions of PP and SBS, under different content of DCP/TAIC initiator system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41543.     

Preparation and dynamic mechanical properties of poly(styrene‐b‐butadiene)‐modified clay nanocomposites

Polybutyl acrylate (PBA) was intercalated into clay by the method of multistep exchange reactions and diffusion polymerization. The clay interlayer surface is modified, and obtaining the modified clay. The structures of the clay‐PBA, clay‐GA (glutamic acid), and the clay‐DMSO (dimethyl sulfoxide) were characterized using X‐ray diffraction (XRD). The new hybrid nanocomposite thermoplastic elastomers were prepared by the clay‐PBA with poly(styrene‐b‐butadiene) block copolymer (SBS) through direct melt intercalation. The dynamic mechanical analysis (DMA) curves of the SBS/modified clay nanocomposites show that partial polystyrene segments of the SBS have intercalated into the modified clay interlayer and exhibited a new glass transition at about 157°C (T_g3). The glass transition temperature of polybutadiene segments (T_g1) and polystyrene segments out of the modified clay interlayer (T_g2) are about ?76 and 94°C, respectively, comparied with about ?79 and 100°C of the neat SBS, and they are basically unchanged. The T_g2 intensity of the SBS‐modified clay decreases with increasing the amounts of the modified clay, and the T_g3 intensity of the SBS‐modified clay decreases with increasing the amounts of the modified clay up to about 8.0 wt %. When the contents of the modified clay are less than about 8.0 wt %, the SBS‐modified clay nanocomposites are homogeneous and transparent. The T_gb and T_gs of the SBS‐clay (mass ratio = 98.0/2.0) are ?78.39 and 98.29°C, respectively. This result shows that the unmodified clay does not essentially affect the T_gb and T_gs of the SBS, and no interactions occur between the SBS and the unmodified clay. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1499–1503, 2002; DOI 10.1002/app.10353     

Synthesis and photocatalytic performance of PVA/TiO2/graphene‐MWCNT nanocomposites for dye removal

TiO₂/graphene‐MWCNT nanocomposite was prepared using solvothermal reaction for the effective distribution of TiO₂ nanoparticles on carbonaceous materials. TiO₂/graphene‐MWCNT nanocomposite was immobilized in poly(vinyl alcohol) (PVA) matrix for a convenient recovery after wastewater purification. MWCNT was incorporated in a nanocomposite not only to prevent the restacking of graphene but also to increase the electron transfer from TiO₂. The detailed characterization of the nanocomposite was performed using SEM, EDX, XRD, XPS, and FTIR. The photocatalytic performance of PVA/TiO₂/graphene‐MWCNT nanocomposite was investigated by UV spectroscopy on the basis of degradation of organic pollutants. PVA/TiO₂/graphene‐MWCNT nanocomposite showed improved photocatalytic decomposition of more than 70% of residual dye left in case of using PVA/TiO₂/graphene nanocomposite due to the improved electron transfer and the higher adsorption of organic pollutants. PVA/TiO₂/graphene‐MWCNT nanocomposite was suitable as a promising material for the recyclable photocatalytic wastewater purification system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40715.     

Synthesis and characterization of poly (styrene‐b‐[(butadiene)1−x‐(ethylene‐co‐butylene)x] ‐b‐styrene) star‐like molecular polymers produced by partial hydrogenation of SBS

This article reports the synthesis and characterization of four arm star‐shaped poly(styrene‐b‐[(butadiene)_1?x‐(ethylene‐co‐butylene)_x]‐b‐styrene) (SBEBS) copolymers. A series of SBEBS copolymers with different compositions of the elastomeric block were produced by hydrogenating a given poly(styrene‐b‐butadiene‐b‐styrene) (SBS) copolymer using a catalyst prepared from bis(η⁵‐cyclopentadienyl)titanium(IV) dichloride and n‐butyllithium. The characterization was accomplished by proton nuclear magnetic resonance spectroscopy (¹H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicate that there is a selective saturation of the polybutadiene block over the polystyrene block; this selectivity was determined by the Ti/Li molar ratio and the concentration of Ti. It was observed that the saturation rate of the 1,2‐vinyl was higher than that of the 1,4‐trans and 1,4‐cis poly(butadiene)‐b isomers. The DSC and DMA results indicate that the degree of hydrogenation had a profound effect on the polymer's relaxation behavior. All samples exhibited a biphasic system behavior with two distinct transitions corresponding to the elastomeric and polystyrene blocks. SBEBS copolymers with higher saturation levels (>33%) exhibited a crystalline character. The TGA results indicated a characteristic weight loss temperature in all samples, with slightly higher thermal degradation stabilities in the materials with higher degrees of saturation. POLYM. ENG. SCI., 54:2332–2344, 2014. © 2013 Society of Plastics Engineers     

Characterization and mechanical properties of exfoliated graphite nanoplatelets reinforced polyethylene terephthalate/polypropylene composites

Recently, graphene and its derivatives have been used to develop polymer composites with improved or multifunctional properties. Exfoliated graphite nanoplatelets (GNP) reinforced composite materials based on blend of polyethylene terephthalate (PET), and polypropylene (PP) compatibilized with styrene–ethylene–butylene–styrene‐g‐maleic anhydride is prepared by melt extrusion followed by injection molding. Characterization of the composites' microstructure and morphology was conducted using field emission scanning electron microscopy, transmission electron microscopy (TEM), X‐ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). Tensile and impact strengths of test specimens were evaluated and the results showed maximum values at 3phr GNP in both the cases. Morphological studies showed that the GNPs were uniformly dispersed within the matrix. Results from XRD analysis showed uniformly dispersed GNPs, which may not have been substantially exfoliated. FTIR spectroscopy did not show any significant change in the peak positions to suggest definitive chemical interaction between GNP and the matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40582.     

Preparation of polylactide/graphene composites from liquid‐phase exfoliated graphite sheets

Polylactide (PLA)/graphene nanocomposites were prepared by a facile and low‐cost method of solution‐blending of PLA with liquid‐phase exfoliated graphene using chloroform as a mutual solvent. Transmission electron microscopy (TEM) was used to observe the structure and morphology of the exfoliated graphene. The dispersion of graphene in PLA matrix was examined by scanning electron microscope, X‐ray diffraction, and TEM. FTIR spectrum and the relatively low I_D/I_G ratio in Raman spectroscopy indicate that the structure of graphene sheets (GSs) is intact and can act as good reinforcement fillers in PLA matrix. Thermogravimetric analysis and dynamic mechanical analysis reveal that the addition of GSs greatly improves the thermal stability of PLA/GSs nanocomposites. Moreover, tensile strength of PLA/GSs nanocomposites is much higher than that of PLA homopolymer, increasing from 36.64 (pure PLA) up to 51.14 MPa (PLA/GSs‐1.0). POLYM. COMPOS., 35:396–403, 2014. © 2013 Society of Plastics Engineers     

Ionic liquid‐modified graphene/poly(vinyl alcohol) composite with enhanced properties

How to preserve the structure integrity of graphene while enhance its dispersion and compatibility in matrix attracts the attention of researchers in graphene/polymer nanocomposite field. In this paper, methacryloxyethyltrimethyl ammonium chloride (DMC), a kind of ionic liquids, was first used to non‐covalently functionalize graphene in the process of graphene oxide (GO) reduction. The as‐modified graphene (DMC‐rGO) was further incorporated into poly(vinyl alcohol) (PVA) matrix by solution casting technique to fabricate DMC‐rGO/PVA composites. The structure and properties of the obtained DMC‐rGO were investigated by X‐ray diffraction analysis (XRD), X‐ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscope (TEM), Atomic force microscopy (AFM), and Raman test. The results showed that graphene could be successfully modified by DMC through ionic–π interaction and the structure integrity of the graphene could be reserved by this non‐covalently approach. Furthermore, after co‐reduction process, some hydroxyl groups were introduced into DMC‐rGO. In virtue of these intrinsic properties of DMC‐rGO, the fabricated DMC‐rGO/PVA composites exhibit considerable enhancements in mechanical properties and remarkable improvements in thermal stability, as well as the enhancement in electrical conductivity at low DMC‐rGO loading. This simple modification approach gives a new opportunity to improve the performances of graphene/polymer composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45006.     

Polypropylene/silica micro‐ and nanocomposites modified with poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)

The effects of different silica loadings and elastomeric content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with 5, 10, 15, and 20 vol % of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) SEBS added to total composite volume were investigated. Four silica fillers differing in size (nano‐ vs. micro‐) and in surface properties (untreated vs. treated) were chosen as fillers. Elastomer SEBS was added as impact modifier and compatibilizer at the same time. The morphology of ternary polymer composites revealed by light and scanning electron microscopies was compared with morphology predicted models based on interfacial properties. The results indicated that general morphology of composite systems was determined primarily by interfacial properties, whereas the spherulitic morphology of polypropylene matrix was a result of two competitive effects: nucleation effect of filler and solidification effect of elastomer. Tensile and impact strength properties were mainly influenced by combined competetive effects of stiff filler and tough SEBS elastomer. Spherulitic morphology of polypropylene matrix might affect some mechanical properties additionally. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41486.     

Studies on the poly(styrene‐b‐butadiene‐b‐styrene)/clay nanocomposites prepared by melt intercalation

Two types of SBS/OMMT composites are prepared by melt blending using a twin‐screw extruder. An X‐ray diffractometer indicates that polymer chains have intercalated into the gallery of the clay. It is shown in TEM photos that the thickness of the layer aggregate in the SBS1301 matrix is approximately 200 Å, but in the SBS4402 matrix the size of the filler particle is in micrometers. When SBS1301 is intermingled into SBS4402/OMMT, the particle size is reduced obviously. The tensile strength and elongation at break of the nanocomposite, SBS1301/OMMT, increase with the addition of OMMT; and when addition is 5phr, they achieve maximum. A small content of OMMT (less than 5phr) can prevent the deterioration of the mechanical properties of the SBS1301/MMT. In addition, a small content of SBS4402 (less than 20 wt %) can improve the mechanical properties of the SBS1301/OMMT composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 146–152, 2005     

Surface changes of corona‐discharge‐treated polyethylene films

Morphological and chemical changes of the surface of low‐density polyethylene (LDPE), linear middle‐density polyethylene (L‐MDPE), and their 80/20 blend were studied by different techniques after corona‐discharge treatment in air and subsequent annealing. The surface tension was determined by wetting; the roughness was measured by atomic force microscope (AFM), and the surface chemical composition was analyzed by X‐ray photoelectron spectroscopy (XPS), whereas the low‐molecular‐mass fraction washed off by chloroform by FTIR. The surface tension of the films increases with the electrode current. The surface roughness depends primarily on the polymer type and is less affected by the corona treatment. At the initial stage of annealing, posttreatment‐type oxidation and hydrophobic recovery are competing. The former is more pronounced in L‐MDPE, the latter in LDPE. After annealing at 50°C for 160 days, hydrophobic recovery becomes predominant in each film studied, which is accompanied by significant smoothening of the surface. According to XPS and FTIR results, this is due to the migration of low‐molecular‐mass components (oligomers, oxidized polymer fractions, and additives) to the surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1529–1541, 2000