Thermophysical Properties and Morphological Changes of PEEK/LCP Blend System on Combined Effect of Polyphosphazene and HNT-COOH

This work explored the structural and morphological changes of poly ether ether ketone/liquid crystal polymer blend system, caused due to combined effect of polyphosphazene and acid-modified halloysite nanotubes. Surface modification of halloysite nanotubes gave these the adequate potential to make an effective combination with polyphosphazene. These were became the most promising factor on enhancement of thermophysical properties of blend system. Surface-treated halloysite nanotubes added nanocomposite drastically improves thermal stability than that of the other untreated nanofiller-based nanocomposites and pure blend. The storage modulus, tensile modulus, and tensile strength values increase due to the superior dispersion of the modified halloysite nanotubes in polymer matrix.     

TPU/PLA nanocomposites with improved mechanical and shape memory properties fabricated via phase morphology control and incorporation of multi-walled carbon nanotubes nanofillers

Shape memory polymer nanocomposites based on thermoplastic polyurethane (TPU)/polylactic acid (PLA) blends filled with pristine multi-walled carbon nanotubes (MWCNTs) and modified MWCNTs─COOH were fabricated by direct melt blending technique and investigated for its morphology, mechanical, thermal, electrical, and shape memory properties. Morphological characterizations by using transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM) revealed better dispersion of MWCNTs─COOH in the polymer blend, which is attributed to the improved interfacial interactions between the polymer blends and MWCNTs-COOH. Loading of the MWCNTs-COOH in the TPU/PLA blends resulted in the significant improvements in the mechanical properties such as tensile strength and elastic modulus and these effects are more pronounced on increasing the MWCNTs─COOH loading amount, when compared to the pristine MWCNTs filled system. Thermal analysis showed that the glass transition temperature of the blends increases slightly with increasing loading of both pristine and modified MWCNTs in the system. The resistance of nanocomposites decreased from 2 × 10¹² Ω to 3.2 × 10¹⁰ Ω after adding 3% MWCNTs─COOH. The shape memory performance tests showed that the enhancement of shape recovery by 252% could be achieved at 3% MWCNTs loading, when compared to that of TPU/PLA blends.     

l-Phenylalanine amino acid functionalized multi walled carbon nanotube (MWCNT) as a reinforced filler for improving mechanical and morphological properties of poly(vinyl alcohol)/MWCNT composite

Carbon nanotube dispersion in polymer matrix is one of the most crucially important aspects in carbon nanotube/polymer composites. This paper is aimed to discuss the considerable improvement in dispersion of multi walled carbon nanotubes (MWNTs) in poly(vinyl alcohol) (PVA) matrix that was attained through bio-functionalization of MWCNTs. Initially, for getting better dispersion in water, pure MWCNTs have been functionalized by l-phenylalanine amino acid. The functionalized MWCNTs (f-MWCNTs) show much enhanced solubility in water. So, effects of modified MWCNT on dispersion in PVA matrix and certain properties of the resulting composites, like; mechanical, thermal and morphological properties were studied. The prepared composites were examined by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. Also, the mechanical and thermal properties of composite films have been investigated and revealed that incorporation of just a few percent of f-MWCNTs can improve the PVA mechanical and thermal properties significantly.     

Preparation and crystallization behavior of multiwalled carbon nanotubes/poly(vinyl alcohol) nanocomposites

The poly(vinyl alcohol) (PVA)‐based nanocomposites embedded with modified multiwalled carbon nanotubes (MWCNTs) were prepared. To enhance the interfacial interaction between MWCNTs and PVA, acid‐treated MWCNTs were grafted with PVA chains, compatibilizing MWCNTs and the matrix. The better dispersion of MWCNTs in PVA matrix was obtained by the introduction of MDI reaction bridges and then PVA molecules onto the surface of MWCNTs. Moreover, strong interaction between MWCNTs and PVA matrix was evidenced through the measurement results of the melting behavior, polarized Raman measurement, and nonisothermal crystallization behavior of the nanocomposites. Owing to the reinforcement of MWCNTs, the tensile strength and modulus of PVA nanocomposite containing 0.9 wt% MWCNTs were increased by 160.7 and 109.2%, respectively, compared to neat PVA. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Property reinforcement of acrylonitrile‐butadiene‐styrene by simultaneous incorporation of carbon nanotubes and self‐prepared copper particles

In this article, copper (Cu) crystallites were successfully prepared via low temperature molten salt method, and the possible formation mechanisms were proposed. The conductive fillers of multiwalled carbon nanotubes (MWCNTs) and as‐prepared Cu particles were designed and introduced into acrylonitrile‐butadiene‐styrene (ABS) blend to prepare different conductive composites. The dispersion states of conductive fillers and the morphologies of the composites were characterized using a field emission scanning electron microscope. The electrical resistivity of different composites was measured. The results showed that Cu and MWCNTs exhibited a synergistic effect in decreasing the electrical resistivity of the Cu/MWCNTs/ABS composites, because Cu that could locate between MWCNTs chain segments provides a better charge transport in the conductive pathways. Compared with pure ABS, the tensile strength, elastic modulus and thermal stability of the Cu/MWCNTs/ABS composites were significantly improved with the incorporation of Cu and MWCNTs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41738.     

Surface modification of CNFs via plasma polymerization of styrene monomer and its effect on the properties of PS/CNF nanocomposites

Carbon nanofibers (CNF) were modified via plasma assisted polymerization in a specially designed reactor. The effect of the plasma reactor conditions, such as power and time, on the extent of the CNFs modification was examined. Polystyrene (PS) coated nanofibers plus PS polymer were then processed in a Brabender torque rheometer mixing chamber to obtain PS/CNF nanocomposites, with 0.5, 1.0, 3.0, and 5.0 wt % of CNF. The effect of the plasma treatment on the dispersion of the nanofibers and on the compatibility between the nanofibers and the polymer matrix was also examined. Modification of the CNFs was assessed by measuring the contact angle of water in a “bed” of nanofibers and by examining its dispersion in several solvents. The morphology of PS/CNF nanocomposites was studied through scanning electron microscopy (SEM). Contact angles decreased in all cases, indicating a change in hydrophobicity of the modified CNFs. This change was confirmed in the CNF dispersion tests in several solvents. SEM micrographs show the difference between the original and the PS coated CNF. In addition, fractured samples show the effect of this treatment, in the sense that the CNF seem to be completely embedded in the polymer matrix, which clearly indicates the high compatibility between the PS and the modified (PS coated) CNF. As a consequence, a much better dispersion of the treated CNF was observed. Finally, the tensile modulus of PS/CNF composites increased slightly with respect to PS when using untreated CNFs, but more than doubled when using plasma treated CNFs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nanocomposite films of poly(vinylidene fluoride) filled with polyvinylpyrrolidone‐coated multiwalled carbon nanotubes: Enhancement of β‐polymorph formation and tensile properties

To improve interactions between carbon nanotubes (CNTs) and poly(vinylidene fluoride) (PVDF) matrix, multiwalled CNTs (MWCNTs) were successfully coated with amphiphilic polyvinylpyrrolidone (PVP) using an ultrasonication treatment performed in aqueous solution. It was found that PVP chains could be attached noncovalently onto the nanotubes' surface, enabling a stable dispersion of MWCNTs in both water and N,N‐dimethylformamide. PVP‐coated MWCNTs/PVDF nanocomposite films were prepared by a solution casting method. The strong specific dipolar interaction between the PVP's carbonyl group (C?O) and the PVDF's fluorine group C?F₂ results in high compatibility between PVP and PVDF, helping PVP‐coated MWCNTs to be homogenously dispersed within PVDF. Fourier transform infrared and X‐ray diffraction characterization revealed that the as‐prepared nanocomposite PVDF films exhibit a purely β‐polymorph even at a very low content of PVP‐wrapped MWCNTs (0.1 wt%) while this phase is totally absent in the corresponding unmodified MWCNTs/PVDF nanocomposites. A possible mechanism of β‐phase formation in PVP‐coated MWCNTs/PVDF nanocomposites has been discussed. Furthermore, the tensile properties of PVDF nanocomposites as function of the content in PVP‐coated MWCNTs were also studied. Results shows that the addition of 2.0 wt% of PVP‐coated MWCNTs lead to a 168% increase in Young's modulus and a 120% in tensile strength. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Effects of three surfactant types of anionic, cationic and non-ionic on tensile properties and fracture surface morphology of epoxy/MWCNT nanocomposites

Three types of surfactants were used to enhance the dispersion of multi-wall carbon nanotubes (MWCNTs) in the epoxy matrix. MWCNTs were separately treated with non-ionic (polyoxyethylene octyl phenyl ether, Triton X-100), cationic (hexadecyl-trimethyl-ammonium bromide, CTAB) and anionic (sodium dodecyl sulfate, SDS) surfactants and their effects were evaluated on the dispersion state and surface chemistry, as well as on the tensile properties and tensile fracture surface morphology of MWCNTs/epoxy nanocomposites. The active surfaces of the carbon nanotubes were characterized by FTIR. The non-ionic surfactant, Triton X-100, had the best effect on dispersion of the MWCNT in the epoxy matrix, thus, positively affecting the tensile parameters of the corresponding nanocomposites which were attributed to the ??bridging?? effects between the MWCNT and epoxy, introduced by the hydrophobic and hydrophilic heads of the corresponding surfactant. Presence of MWCNTs as reinforcing agent increased the elastic modulus of nanocomposites, indicating the improved interfacial adhesion between CNTs and polymer matrix. The regions of nucleation and propagation of cracks were clearly seen in the SEM micrographs of the tensile fracture surface of the nanocomposites. The cracks deviated on reaching the carbon nanotubes. The dispersing aiding capabilities of the three surfactants used in the present study were as follows: cationic?<?anionic?<?non-ionic.     

Improvement in properties of multiwalled carbon nanotube/polypropylene nanocomposites through homogeneous dispersion with the aid of surfactants

The effects of different surfactants on the properties of multiwalled carbon nanotubes/polypropylene (MWCNT/PP) nanocomposites prepared by a melt mixing method have been investigated. Sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS) were used as a means of noncovalent functionalization of MWCNTs to help them to be dispersed uniformly into the PP matrix. The effects of these surfactant‐treated MWCNTs on morphological, rheological, thermal, crystalline, mechanical, and electrical properties of MWCNT/PP composites were studied using field emission scanning electron microscopy, optical microscopy, rheometry, tensile, and electrical conductivity tests. It was found that the surfactant‐treatment and micromixing resulted in a great improvement in the state of dispersion of MWCNTs in the polymer matrix, leading to a significant enhancement of Young's modulus and tensile strength of the composites. For example, with the addition of only 2 wt % of SDS‐treated and NaDDBS‐treated MWCNTs, the Young's modulus of PP increased by 61.1 and 86.1%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

碳纳米管改性方法对聚酰胺11性能影响研究

采用酸处理和聚乙烯亚胺(PEI)表面修饰两种方法对多壁碳纳米管(MWCNTs)进行改性,将改性碳纳米管与聚酰胺11(PA11)熔融共混,制备了聚酰胺11/酸刻蚀碳纳米管(PA11/a-MWCNTs)和聚酰胺11/聚乙烯亚胺接枝碳纳米管(PA11/PEI-MWCNTs)复合材料,并通过扫描电子显微镜(SEM)、热重分析仪...     

Preparation and Characterization of Polycarbonate-Blend-Raw/Functionalized Multi-Walled Carbon Nano Tubes Mixed Matrix Membrane for CO2 Separation

Membrane composed of PC as base of polymer matrix with different ratio of multiwall carbon nano tubes (MWCNTs) as nanofillers and poly ethylene glycol (PEG) as second polymer was prepared by solution casting method. Both raw-MWCNTs (R-MWCNTs) and functionalized carboxyle-MWCNTs (C-MWCNTs) were used in membrane preparation. The MWCNTs loading ratio and pressure effects on the gas transport properties of membranes were examined in relation to pure He, N₂, CH₄, and CO₂ gases. Results showed that the use of C-MWCNT instead of R-MWCNTs in mixed matrix membranes (MMMs) fabrication with base of PC provides better performance and also it increases (CO₂/CH₄) and (CO₂/N₂) selectivities to 27.38 and 25.42 from 25.45 and 19.24, respectively (at 5 wt% of MWCNTs). PEG as the second rubbery polymer was utilized to improve the separation performance and mechanical properties. In blend MMMs, highest (CO₂/CH₄) selectivity at 2 bar pressure increased to 35.64 for PC/PEG/C-MWCNT blend MMMs which was 27.28 for PC/MWCNTs MMMs at 10 wt%. Increase of feed pressure led to gas permeability and gas pair selectivity improvement in approximately all of membranes. Analysis of mechanical properties showed improvement in tensile modules with the increase of MWCNTs loading ratio and use of PEG in prepared MMMs.     

The enhanced mechanical properties of a covalently bound chitosan‐multiwalled carbon nanotube nanocomposite

In the present work, chitosan (CS)‐grafted multiwalled carbon nanotube (MWCNT) nanocomposites were prepared via covalently bonded CS onto MWCNTs that had weight fractions of MWCNTs ranging from 0.1 to 3.0 wt % by a simple method of solution casting. The structure, morphology, and mechanical properties of the films were investigated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, optical microscopy, wide‐angle X‐ray diffraction, contact angle, and tensile testing. The results indicated that the CS chains were attached onto the MWCNTs successfully via covalent linkages. More interestingly, the MWCNTs provided a matrix that facilitated the crystallization of CS. Compared with the pure CS, the tensile strength and Young's modulus of the nanocomposites were enhanced significantly from 39.6 to 105.6 MPa and from 2.01 to 4.22 GPa with an increase in the MWCNT loading level from 0 to 3.0 wt %, respectively. The improvement in the tensile strength and modulus were ascribed to the uniform dispersion of MWCNTs covalently linked to the CS matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of surface modification of carbon nanotube on microstructures and properties of polyamide 66/multiwalled carbon nanotube composites

The melt‐mixing polyamide 66 (PA66) composite samples that incorporated pure, acid‐ and amine‐functionalized multiwalled carbon nanotubes (MWCNTs) were prepared in order to enhance mechanical and frictional properties of PA66 composites. The homogeneous dispersion of amine‐functionalized MWCNTs (D‐MWCNTs) in PA66 matrix was observed from the significantly uniform morphology of tensile fractured surface of the composites. Differential scanning calorimetry measurement indicates that D‐MWCNTs acted as effective nucleation agent for PA66 matrix and the crystallinity of PA66 was increased. The fracture stress and tensile modulus of the composites were significantly improved with the incorporation of D‐MWCNTs, owing to the good dispersion of D‐MWCNTs. Compared with PA66, the PA66 composites with 1.0 wt% D‐MWCNTs were improved considerably in both wear and friction properties owing to the change of the tribological mechanisms. The good dispersion of D‐MWCNTs in PA66 and good interface compatibility between D‐MWCNTs and PA66 favored the formation of a thin layer on the contact surfaces during wear and friction test, which played an important role in reducing wear and friction of the composite and in suppressing the transverse cracks. These results prove the importance of D‐MWCNTs in a positive change of the mechanical and frictional properties of PA66 composites and suggest the applicability prospect of PA66/D‐MWCNTs composites in engineering components.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Miscibility and mechanical properties of poly(ether imide)/poly(ether ether ketone)/liquid crystalline polymer ternary blends

This paper is concerned with a novel ternary blend composed of poly(ether imide) (PEI), poly(ether ether ketone) (PEEK) and a liquid crystalline polymer (LCP; HX4000, Du Pont). Different compositions were prepared by extrusion and injection moulding. Dynamic mechanical thermal analysis and the observation of the fracture surfaces, before and after annealing, allowed determination of the cold crystallization temperatures and miscibility behaviour of these systems. PEEK/PEI blends are known from previous studies to be miscible at all compositions. In this case it was observed that the PEEK/HX4000 blend was miscible up to 50 wt% HX4000 but partially miscible above this value. The PEI/HX4000 blends were found to be partially miscible in the whole concentration range. As a result, some ternary blend compositions exhibited only one phase, while others exhibited two phases. The measurement of the tensile properties showed that ternary blends with high modulus can be obtained at high LCP loadings, while compositions with high ultimate tensile strength can be obtained with high loadings of PEI or PEEK.     

MWCNT/Hectorite hybrid filled acrylonitrile butadiene rubber/ ethylene-co-vinyl acetate blend nanocomposites: preparation and properties

Multiwalled carbon nanotube/hectorite hybrid filler (HMH) was prepared by simple dry grinding method. It was subsequently used for the reinforcement of technologically compatible acrylonitrile butadiene rubber (NBR)/ ethylene-co-vinyl acetate (EVA) blend through solution intercalation method. Analysis of the prepared blend nanocomposites confirms homogeneous dispersion of the constituent fillers in the polymer matrix and significant interaction between two types of constituent fillers. Mechanical properties of NBR/EVA blend are significantly improved with HMH content up to 4 wt.% followed by reversion. Maximum improvement observed in tensile strength, elongation at break and toughness are 106%, 37% and 171% respectively without significant rise in Young’s modulus. Results also show best dynamic mechanical and dielectric response at 4 wt.% and 3 wt.% HMH content respectively. Enhanced mechanical, dynamic mechanical and dielectric properties of the blend nanocomposites attained may be attributed to fair degree of compatibility between the two polymer matrices, homogeneous dispersion of fillers and improved polymer-filler interaction.     

Biodegradable PBAT/Starch Nanocomposites

Starch-based biodegradable banocomposites of poly(butylene adipate-co-terephthalate) [PBAT] and organically modified nanoclays were prepared using melt intercalation technique in Haake Torque Rheocord 9000. Two different organically modified nanoclays Cloisite C20A and Cloisite C30B at various wt% (1, 3, 5) have been used for fabrication of nanocomposites. Starch was gelatinized to prepare thermoplastic starch (TPS) for increasing the compatibility with the PBAT matrix. Subsequently, films of PBAT/TPS blends at various TPS contents (10, 20, 30, 40) wt% and PBAT/TPS Organoclay biodegradable blend nanocomposites at different wt% of nanoclays were prepared using solvent casting method. The interfacial region between the biodegradable polymer matrix and the clays were also modified with grafting of Maleic anhydride (MA) with PBAT chains, during melt blending through two stage reactive extrusion process. Mechanical tests revealed an increase in tensile modulus and elongation at break with the incorporation of 30 wt% TPS and C30B nanoclay to the tune of 44.45% and 776.9% as compared with PBAT matrix. PBAT/TPS30 wt%/C30B3wt% shows maximum tensile modulus and elongation at break due to intercalation of silicate layers resulting from similarity in the surface polarity and interactions of C30B with TPS. Morphology of PBAT/TPS30%/C30B3% biodegradable blend nanocomposite studied using WAXD and SEM indicated intercalation and improved dispersion of TPS within PBAT with incorporation of C30B. Dynamical mechanical analysis of PBAT/TPS/C30B biodegradable blend nanocomposite revealed an increase of storage modulus and glass transition temperatures of PBAT with addition of nanoclays. Further Biodegradation test also confirmed higher biodegradability of PBAT in presence of TPS and C30B.     

Liquid-crystal polymer fiber production and reinforcing in ribbons of poly(ether imide)/vectra-B blends

Blends of poly(ether imide) (PEI) with a liquid-crystal polymer (Vectra-B950) were extruded into ribbon. Two PEI-rich compositions at three different draw ratios were obtained, and the miscibility and morphology of the blends analyzed. The tensile properties of the ribbons were determined, both in the processing and in the perpendicular direction and were compared with those of the pure PEI. Results showed that PEI/Vectra blends are immiscible and that complex structures were obtained as a consequence of extrusion. The blend composition and the draw ratio determined to a great extent the mechanical properties of the blends. The interfacial adhesion between blend components is low, but enough to break the LCP fibers when significant aspect ratios are attained.     

表面改性碳纳米管/天然橡胶复合材料的制备及性能研究

采用多巴胺对多壁碳纳米管(MWCNTs)进行非共价改性,得到多巴胺改性MWCNTs(简称PCNT)。将PCNT作为填料加入天然胶乳中制备PCNT/天然橡胶(NR)复合材料,并研究其性能。透射电子显微镜(TEM)分析结果表明MWCNTs经过多巴胺改性后在水中的分散效果明显改善。PCNT/NR复合材料的拉伸强度和撕裂强度明显提高,拉伸强度由22.7 MPa升至28.4 MPa,撕裂强度由26 kN·m^-1升至40 kN·m^-1。多巴胺用量适当的PCNT在NR基体中分散更均匀,填料与橡胶的相互作用较强,能够形成较好的填料网络结构,PCNT/NR复合材料的表面电阻显著降低。     

The production of functionalized multiwall carbon nanotube/amino acid-based poly(amide–imide) composites containing a pendant dopamine moiety

The high compatibility of amino-acid based poly(amide–imide) (PAI) as a polymer matrix for acid-modified multi-walled carbon nanotubes (MWCNTs) is discussed. PAI was synthesized from the direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-l-isoleucine with a dopamine-based diamine, 3,5-diamino-N-(3,4-dihydroxy-phenethyl)benzamide, in a medium consisting of a molten salt, tetrabutylammonium bromide, and triphenyl phosphite as the activator under microwave radiation. To obtain a homogeneous dispersion of MWCNTs in the PAI matrix, acid-functionalized MWCNTs were used. Composites containing 5, 10, and 15 wt.% MWCNT–COOH exhibited a relatively good dispersion on the macroscopic scale. MWCNT/PAI composite films have been prepared by casting a solution of precursor polymer containing MWCNTs into a thin film and its tensile properties examined. Incorporation of MWCNTs improved the mechanical properties significantly. Composites were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, and thermal gravimetric analysis. The thermal stability of the composites containing the CNTs was improved due to the increased interfacial interaction between the PAI matrix and the modified CNTs and their good dispersion.     

Investigation on production and characterization of bionanocomposites based on surface functionalized multi-walled carbon nanotubes and optically active poly(ester-imide) having L-isoleucine units

Carboxylic functionalized multi-walled carbon nanotubes (MWCNTs) have been incorporated to biodegradable poly(ester-imide) (PEI) matrix and the effect of the carboxylated-MWCNT on the thermal and morphological properties of MWCNT-reinforced bionanocomposites (BNCs) was demonstrated. Chiral PEI was synthesized from a step-growth polymerization of amino acid based diacid (4) with 4,4′-thiobis(2-tert-butyl-5-methylphenol) (5) promoted by tosyl chloride in pyridine and N,N-dimethyl formamide solution. The resulting BNCs were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The homogeneous dispersion of MWCNTs throughout PEI matrix and strong interfacial adhesion between them were achieved in the obtained BNCs as evidenced by FE-SEM and TEM images. The results from TGA indicated that the thermal stability of the resulting BNCs was obviously improved in comparison with the pure PEI.