Nanocomposite fibers of poly(ethylene terephthalate) with montmorillonite and mica: thermomechanical properties and morphology

The thermal stabilities, mechanical properties, and morphologies of nanocomposites of poly(ethylene terephthalate) (PET) with two different organoclays are compared. Dodecyltriphenylphosphonium‐montmorillonite (C₁₂PPh‐MMT) and dodecyltriphenylphosphonium‐mica (C₁₂PPh‐Mica) were used as reinforcing fillers in the fabrication of PET hybrid fibers. The variations of their properties with organoclay content in the polymer matrix and draw ratio (DR) are discussed. Transmission electron microscopy micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nanoscale, although some clay particles are agglomerated. It was also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the PET hybrid fibers. Even polymers with low organoclay contents (1–5 wt%) were found to exhibit much higher strength and modulus values than pure PET. In the case of C₁₂PPh‐MMT/PET, the values of the tensile mechanical properties of the hybrid fibers were found to decrease linearly with increases in DR from 1 to 16. However, the tensile mechanical properties of the C₁₂PPh‐Mica hybrid fibers were found to be independent of DR. Copyright © 2006 Society of Chemical Industry     

Poly(ethylene terephthalate) nanocomposites by in situ interlayer polymerization: the thermo-mechanical properties and morphology of the hybrid fibers

Nanocomposites of poly(ethylene terephthalate) (PET) with C₁₂PPh-MMT as an organoclay were synthesized by using the in situ interlayer polymerization approach. The PET nanocomposites were melt-spun at different organoclay contents and different draw ratios to produce monofilaments. The thermo-mechanical properties and the morphologies of the PET nanocomposites were examined by using a differential scanning calorimeter, a thermogravimetric analyzer, a wide angle X-ray diffactometer, scanning and transmission electron microscopes, and a universal tensile machine. Some of the clay particles were well dispersed in the PET matrix, and some of them were agglomerated at a size level of greater than approximately 10 nm. The thermal stability and the tensile mechanical properties of the PET hybrid fibers increased with increasing clay content at a DR=1. However, the values of the ultimate tensile strength and the initial modulus of the hybrid fibers decreased markedly with increasing DR from 1 to 16.     

Preparation of poly(ethylene terephthalate) nanocomposite fibers incorporating a thermally stable organoclay

Summary A series of poly(ethylene terephthalate) (PET) nanocomposites containing organically-modified mica (HB-Mica) were prepared by in-situ interlayer polymerization of dimethyl terephthalate and ethylene glycol. The PET nanocomposites, which contained organoclay loadings of 0 to 2 wt %, were melt-spun to produce monofilaments with various draw ratios. Some of the clay particles appeared well dispersed within the PET matrix, while others were found to form agglomerates with sizes greater than 20 nm. The addition of a small amount of organoclay was sufficient to improve the thermo-mechanical properties of the PET hybrid fibers. Both the thermal stability and the mechanical tensile properties increased with increasing clay content for draw ratios of 1–16.     

Synthesis and characterization of poly(butylene terephthalate) nanocomposite fibers: Thermo‐mechanical properties and morphology

Nanocomposites of poly(butylene terephthalate) (PBT) with the organoclay C₁₂PPh‐MMT were prepared using in situ intercalation polymerization. Hybrids with various organoclay contents were processed for fiber spinning to examine their thermal behavior, tensile mechanical properties, and morphologies for various draw ratios (DRs). The thermal properties (T_g, T_m, and T_Dⁱ) of the hybrid fibers were found to be better than those of pure PBT fibers and were unchanged by variation of the organoclay loading up to 2 wt %. However, these thermal properties remained unchanged for DRs ranging from 1 to 18. Most clay layers were dispersed homogeneously in the matrix polymer, although some clusters were also detected. The tensile properties of the hybrid fibers increased gradually with increasing C₁₂PPh‐MMT content at DR = 1. However, the ultimate strengths and initial moduli of the hybrid fibers decreased markedly with increasing DR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1247–1254, 2006     

Poly(trimethylene terephthalate) nanocomposite fibers comprising different organoclays: Thermomechanical properties and morphology

Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C₁₂PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C₁₂PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C₁₂PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006     

Polyester nanocomposite fibers: comparison of their properties with poly(ethylene terephthalate) and poly(trimethylene terephthalate) (II)

Summary Two polyester nanocomposites were synthesized, one with poly(ethylene terephthalate) (PET) and the other with poly(trimethylene terephthalate) (PTT), by using organoclay. The in-situ interlayer polymerization method was used to disperse the organoclay in polyesters at different organoclay contents and at different draw ratios to produce monofilaments. The thermal stability and tensile mechanical properties increased with increasing organoclay content at a DR=1 . However, the values of the tensile mechanical properties of the hybrid fibers decreased with increasing DR. The reinforcing effects of the organoclay of the PET hybrid fibers were higher than those of the PTT hybrid fibers.     

Poly(butylene terephthalate)/organoclay nanocomposites prepared by in situ interlayer polymerization and its fiber (II)

Intercalated nanocomposites with poly(butylene terephthalate) (PBT) incorporated between the montmorillonite layers were synthesized from dimethyl terephthalate and 1,4-butane diol by using an in situ interlayer polymerization. The PBT nanocomposites were melt-spun at different organoclay contents to produce monofilaments. The samples were characterized by using wide angle X-ray diffraction, electron microscopy, thermal analysis, and tensile testing. The extent of the clay layer in the PBT was confirmed by using X-ray diffraction and electron microscopy, and the clay layer was found to be highly dispersed on a nanometer scale. The addition of only a small amount of organoclay was enough to improve the thermo-mechanical properties of the PBT hybrid fibers. The hybrids were extruded with various draw ratios (DRs) to examine the tensile mechanical property of the fibers. At DR=1, the ultimate tensile strength of the hybrid fibers increased with the addition of clay up to a critical content and then decreased. However, the initial modulus monotonically increased with increasing amount of organoclay in the PBT matrix. When the DR was increased from 1 to 6, for example, the strength and the initial modulus values of the hybrids containing 3 wt% organoclay decreased linearly.     

Poly(ethylene terephthalate) nanocomposite fibers with new organomica via in situ intercalation

Poly(ethylene terephthalate) (PET) nanocomposites with a newly synthesized organomica (C₁₆BIMD‐Mica) were obtained by using the in situ interlayer polycondensation of ethylene glycol with dimethylterephthalic acid. The PET hybrids were melt‐spun to produce monofilaments with various organoclay contents and draw ratios. The thermomechanical properties and morphologies of the PET hybrid fibers were determined using differential scanning calorimetry, thermogravimetric analysis, wide angle X‐ray diffraction, electron microscopy (SEM and TEM), and a universal tensile machine. The XRD analyses and TEM micrographs showed that the levels of exfoliation and intercalation could be controlled by varying the clay content. The thermomechanical properties of the PET hybrid fibers were found to be better than those of pure PET fibers. POLYM. ENG. SCI., 47:1820–1826, 2007. © 2007 Society of Plastics Engineers     

Poly(trimethylene terephthalate) nanocomposite fibers by in situ intercalation polymerization: thermo-mechanical properties and morphology (I)

A series of poly(trimethylene terephthalate) (PTT) nanocomposites, containing an organically modified montmorillonite (C₁₂PPh-MMT), were prepared by in situ intercalation polymerization of dimethyl terephthalate (DMT) and 1,3-propanediol (PDO). The PTT nanocomposites were melt-spun at different organoclay contents and different draw ratios (DRs) to produce monofilaments. The nanocomposites were characterized by X-ray diffraction, electron microscopy, universal tensile testing, differential scanning calorimetry and thermogravimetric analysis. Some of the clay particles appeared well dispersed within the PTT matrix, while others were found to agglomerate with a size greater than 10 nm. The addition of a small amount of C₁₂PPh-MMT was sufficient to improve the thermo-mechanical properties of the PTT hybrid fibers. Both the thermal stability and the tensile strength increased with increasing clay content at DR=1. As the DR was increased from 1 to 9, the ultimate tensile strength of the hybrid fibers decreased, while the initial modulus remained constant.     

Comparison of Thermomechanical Properties and Morphologies of Polyester Nanocomposite Fibers: PBT,PET, and PTT

Nanocomposites of three different polyesters with dodecyltriphenyl-phosphonium-montmorillonite (C₁₂PPh-MMT) organoclay are compared with respect to their thermal properties, mechanical properties, and morphologies. Poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and poly(trimethylene terephthalate) (PTT) were used as matrix polymers in the fabrication of polyester nanocomposite fibers. The variations in their properties with respect to both the organoclay content in the polymer matrix and the draw ratio (DR) are discussed. Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nanoscale, although some clay particles are agglomerated. The results additionally show that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the polyester nanocomposite fibers.     

Colorless polyimide nanocomposite films: Thermomechanical properties,morphology, and optical transparency

Polyimide (PI)/organoclay hybrid films were prepared by the solution intercalation method, using dodecyltriphenylphosphonium‐mica (C₁₂PPh‐Mica) as the organoclay. The variations with organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids were examined for concentrations from 0 to 1.0 wt %. For low clay contents (≤ 0.5 wt %), the clay particles are better dispersed in the matrix polymer, without the formation of large agglomerates of particles, than they are for high clay contents. However, agglomerated structures form and become denser in the PI matrix for clay contents ≥ 0.75 wt %. This is in agreement with the observed trends in the thermomechanical properties and the optical transparency, which worsen drastically when the clay content of the C₁₂PPh‐Mica/PI hybrids reaches 0.75 wt %. However, when the amount of organoclay in the hybrid is 0.75 wt %, the initial modulus of the hybrid film is at its maximum value. The PI hybrid films were found to exhibit excellent optical transparencies and to be almost colorless. It was found, however, that the transparency decreases slightly with increases in the organoclay content because of agglomeration of the clay particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation,microstructure, mechanical,and thermal properties of in situ polymerized polyimide/organically modified sericite mica composites

In this work, sericite mica was initially modified with a multi‐step procedure and the novel composites of polyimide (PI) with the organophilic sericite mica were subsequently synthesized via in situ polymerization technique. XRD patterns revealed d₀₀₂‐spacing of clay was expanded from 0.99 to 2.77 nm. TEM photographs indicated majority of the organoclay exhibited an exfoliated morphology structure in composites with 5 wt% filler loading. Several critical properties of composites such as thermal stability, mechanical property, and storage modulus were tremendously enhanced with the increasing organoclay loading. Especially, the glass transition temperature of composites with 7 wt% organoclay addition revealed a 72°C increment compared with pristine PI, indicating greater improvement than the reported literature values. POLYM. COMPOS., 37:2243–2251, 2016. © 2015 Society of Plastics Engineers     

Preparation and characterization of polyurethane–organoclay nanocomposites

Nanocomposite polyurethane (PU)–organoclay materials have been synthesized via in‐situ polymerization. The organoclay is first prepared by intercalation of tyramine into montmorillonite (MMT)‐clay through ion exchange process. The syntheses of polyurethane–organoclay hybrid films containing different ratios of clay were carried out by swelling the organoclay into diol and diamine followed by addition of diisocyanate and then cured. The nanocomposites with dispersed and exfoliated structure of MMT were obtained as evidenced by X‐ray diffraction and scanning electron microscope. X‐ray diffraction showed that there is no peak corresponding to d₀₀₁ spacing in organoclay with the ratios up to 20 wt%. SEM images confirmed the dispersion of nanometer silicate layers in the polyurethane matrix. Also, it was found that the presence of organoclay leads to improvement in the mechanical properties. The tensile strength was increased with increasing the organoclay contents to 20 wt% by 221% in comparision to the PU with 0% organoclay. POLYM. COMPOS. 28:108–115, 2007. © 2007 Society of Plastics Engineers     

Structure and properties of melt‐spun PET/MWCNT nanocomposite fibers

Polyethylene terephthalate (PET) melt‐spun fibers were modified with multiwall carbon nanotubes (MWCNT) to obtain conductive microfibers smaller than 90 μm in diameter. Physical properties such as crystallinity and orientation of as‐spun fibers were studied by X‐ray diffraction, Raman spectroscopy, and microscopy techniques at different draw ratios (DR) and MWCNT concentrations. Morphological and orientation analysis of MWCNT after melt‐spinning process showed agglomerates formation and highly oriented CNTs. The study of the orientation of PET crystalline phase in drawn fibers proved that the addition of nanoparticles decreases the orientation of crystalline units inside the fibers. The orientation of MWCNT as well as that of PET chains was studied using Raman spectroscopy at different DR and a high degree of CNT orientation was observed under high DR conditions. Mechanical and electrical properties of as‐spun fibers were also investigated. Our results showed that it was possible to achieve conductive fibers at a MWCNT concentration of 2% w/w, and more conductive fibers using higher DR were also obtained without increasing the MWCNT concentration. Mechanical properties results showed interestingly high value of maximum tensile strain at break (ε_max) of nanocomposite fibers, up to three times more than pure PET fibers. POLYM. ENG. SCI., 50:1956–1968, 2010. © 2010 Society of Plastics Engineers     

Synthesis and characterization of colorless polyimide nanocomposite films

A poly(amic acid) was prepared through the reaction of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 2,2′‐bis(trifluoromethyl) benzidine in N,N‐dimethylacetamide. Hybrid films were obtained from blend solutions of the precursor polymer and the organoclay dodecyltriphenylphosphonium–mica, with the organoclay content varying from 0 to 1.0 wt %. The cast films of poly(amic acid) were heat‐treated at different temperatures to create polyimide (PI) hybrid films. These PI hybrid films showed excellent optical transparency and were almost colorless. The intercalation of PI chains in the organoclay was examined with wide‐angle X‐ray diffraction and electron microscopy. In addition, the thermomechanical properties were tested with differential scanning calorimetry and thermogravimetric analysis, and the gas permeability was determined. The addition of only a small amount of the organoclay was sufficient to improve the thermal and mechanical properties of the PI, with the maximum enhancement being observed with 0.5 wt % organoclay. However, the water vapor permeability decreased with the clay loading increasing from 0 to 0.5 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and characterization of poly(styrene‐co‐butadiene) and polybutadiene rubber/clay nanocomposites

Poly(styrene‐co‐butadiene) rubber (SBR) and polybutadiene rubber (BR)/clay nanocomposites have been prepared. The effects of the incorporation of inorganically and organically modified clays on the vulcanization reactions of SBR and BR were analysed by rheometry and differential scanning calorimetry. A reduction in scorch time (t_s1) and optimum time (t₉₅) was observed for both the rubbers when organoclay was added and this was attributed to the amine groups of the organic modifier. However, t_s1 and t₉₅ were further increased as the clay content was increased. A reduction in torque value was obtained for the organoclay nanocomposites, indicating a lower number of crosslinks formed. The organoclays favoured the vulcanization process although the vulcanizing effect was reduced with increasing clay content. The tensile strength and elongation of SBR were improved significantly with organoclay. The improvement of the tensile properties of BR with organoclay was less noticeable than inorganic‐modified clay. Nevertheless, these mechanical properties were enhanced with addition of clay. The mechanical properties of the nanocomposites were dependent on filler size and dispersion, and also compatibility between fillers and the rubber matrix. Copyright © 2004 Society of Chemical Industry     

Polyimide nanocomposite with a hexadecylamine clay: Synthesis and characterization

A poly(amic acid) was prepared by the reaction of 3,3′‐dihydroxybenzidine and pyromellitic dianhydride in N,N‐dimethylacetamide. Hexadecylamine was used as an organophilic alkylamine in organoclay. Cast films were obtained from blend solutions of the precursor polymer and the organoclay. The cast film was heat treated at different temperatures to create polyimide (PI) hybrid films. We set out to clarify the intercalation of PI chains to hexadecylamine–montmorillonite (C₁₆–MMT) and to improve thermal and tensile properties and the gas barrier. It was found that the addition of only a small amount of organoclay was enough to improve both the thermal and the mechanical properties of PIs. Maximum enhancement in the ultimate tensile strength for PI hybrids was observed for the blends containing 4% C₁₆–MMT. The initial modulus monotonically increased with further increases in C₁₆–MMT content. Water vapor permeability was decreased with increasing clay loading from 1 to 8 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2294–2301, 2002     

A modified method for processing and characterization of organoclay‐based poly(ethylene terephthalate) nanocomposite fibers

In the current study, in order to prepare poly(ethylene terephthalate) (PET)/organoclay nanocomposite fibers, a slurry‐compounding method (SCM) was applied and compared to conventional melt‐compounding method (CMM) in terms of the dispersion of organoclays and the performance of the spun and or drawn fibers. The organoclays were synthesized by using three different alkyl phosphonium salts and compared with commercially available alkyl ammonium‐modified organoclays in terms of thermal stability and basal spacing. It was found that the alkyl phosphonium salts exhibited higher thermal stability and basal spacing with respect to commercial alkyl ammonium organoclays. Among them, tributylhexadecylphosphonium bromide resulted in superior properties; therefore, it was used to prepare the nanocomposite PET fibers. The organoclay content of 0.1–1 wt% was taken as the material parameter. It was demonstrated that the SCM yielded better dispersion of organoclays with respect to CMM. The drawn nanocomposite fibers prepared via SCM exhibited improved tensile strength and modulus in comparison to the neat‐PET. The maximum tensile properties for fibers were obtained at 0.5% organoclay loading in SCM. The thermal properties and the percentage of crystallinity were investigated by differential scanning calorimetry analysis. In addition, Fourier transform infrared spectroscopy was utilized to obtain the percentage of crystallinity of the fibers. POLYM. COMPOS., 34:887–896, 2013. © 2013 Society of Plastics Engineers     

Mechanical properties and failure surface morphology of amine‐cured epoxy/clay nanocomposites

The tensile and impact properties of amine‐cured diglycidyl ether of bisphenol A based nanocomposites reinforced by organomontmorillonite clay nanoplatelets are reported. The sonication processing scheme involved the sonication of the constituent materials in a solvent followed by solvent extraction to generate nanocomposites with homogeneous dispersions of the organoclay nanoplatelets. The microstructure of the clay nanoplatelets in the nanocomposites was observed with transmission electron microscopy, and the clay nanoplatelets were well dispersed and were intercalated and exfoliated. The tensile modulus of epoxy at room temperature, which was above the glass‐transition temperature of the nanocomposites, increased approximately 50% with the addition of 10 wt % (6.0 vol %) clay nanoplatelets. The reinforcing effect of the organoclay nanoplatelets was examined with respect to the Tandon–Weng and Halpin–Tsai models. The tensile strength was improved only when 2.5 wt % clay nanoplatelets were added. The Izod impact strength decreased with increasing clay content. The failure surfaces of the nanocomposites were observed with environmental scanning electron microscopy and confocal laser scanning microscopy. The roughness of the failure surface was correlated with the tensile strength. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 281–287, 2005     

Physical properties and cure characteristics of natural rubber/nanoclay composites with two different compatibilizers

The effects of epoxidized natural rubber (ENR) and maleic anhydride‐grafted polybutadiene (PB‐g‐MA) as compatibilizers to rubber formulations with and without organo‐modified layered silicates are investigated. The physical properties and curing characteristics of composites are studied by moving die rheometer, rubber process analyzer, tensile, tear, and hardness testing. The state of organoclay intercalation was determined by X‐ray diffraction method. The addition of compatibilizers, especially ENR 50, results in further intercalation or exfoliation of the organoclay that increased the clay dispersion in the rubber matrix. ENR 50 with organo‐modified clay improves the physical properties and changes the curing profile. The addition of PB‐g‐MA without organoclay increases the tensile strength (σ_max) by increasing the stock viscosity of the rubber compound. Interestingly, simultaneous increase in hardness and σ_max is achieved in the presence of both compatibilizers, a characteristic that is difficult to achieve and sometimes required in rubber processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011