From PET Nanofibrils to Nanofibrillar Single‐Polymer Composites

The preparation of nanofibrillar composite (NFC) materials using single‐polymer nanofibrils as starting materials is described. Such a possibility is offered by (i) the concept of polymer/polymer NFCs, which have recently been manufactured and represent a further development in the field of microfibril‐reinforced composites, and (ii) the opportunity to isolate neat nanofibrils through selective dissolving of the second blend component. The resulting nanofibrillar single‐polymer composites are characterized by superior mechanical properties (the tensile modulus and strength are improved up to 350%), competing with glass‐fiber‐reinforced PET.

     

Effect of Reinforcement Orientation on the Mechanical Properties of Microfibrillar PP/PET and PET Single‐Polymer Composites

In situ PET microfibrils are created by drawing melt‐blended PP and PET. The drawn blend is used to prepare polymer/polymer MFCs, and isolated PET microfibrils are used for the manufacturing of MF‐SPCs. Samples are prepared with different fibril orientations to determine the effect of orientation on the mechanical properties of the two types of composites. The resulting composites show improvements in stiffness of 77% for uniaxial MFCs, and 125% for uniaxial MF‐SPCs, with the highest recorded modulus of 8.57 GPa for a uniaxial MF‐SPC sample. SEM observations confirm that the fibrillar structure and excellent alignment is maintained. The changes in the reinforcement effect with orientation are very similar to those predicted by the rule of mixtures for the crossply.

     

Improving Poly(ethylene terephthalate) Through Self‐nucleation

As‐received poly(ethylene terephthalate) (asr‐PET) may be reorganized by precipitation from trifluoroacetic acid upon gradual addition to a large excess of rapidly stirred acetone (p‐PET). Unlike asr‐PET, p‐PET repeatedly crystallizes rapidly from the melt, and can be used in small quantities (a few %) as an effective self‐nucleating agent to control and improve the bulk semi‐crystalline morphology and properties of asr‐PET. Nuc‐PET film has significantly increased hardness and Young's modulus and is much less permeable to CO₂, while its un‐drawn fibers exhibit higher tenacities and moduli. Because nuc‐PET contains no incompatible additives, it may be readily recycled.

     

Poly(ethylene terephthalate) ionomer based clay nanocomposites produced via melt extrusion

Poly(ethylene terephthalate) ionomer (PETI)/organically-modified montmorillonite clay (OMC) nanocomposites were prepared via melt extrusion. Sulfonated PET containing various incorporations of ionic comonomer and clay modifications were investigated. The random incorporation of ionic functionalities along the PET backbone enhances interactions between the matrix polymer and montmorillonite clay resulting in the creation of polymer-clay nanocomposites exhibiting a predominately exfoliated morphology. The morphology is correlated with mechanical properties and crystallization behavior. It is found that incorporation of clay into the random ionomers leads to increased mechanical properties and slower crystallization rates.     

PET/PTT共混聚酯的等温结晶行为

使用差示扫描量热仪(DSC)研究不同比例的PET/P1T共混聚酯在205℃的等温结晶行为,并使用Avrami方程对其等温结晶过程进行研究.结晶半周期t1/2,总结晶速率常数k和Avrami指数n的变化表明:在共混体系中,对于PET和PTT而言,另一组分的加入都会对结晶产生阻碍作用,PET与P1T相互影响成核与晶体生长机理.     

Characterisation of melt‐processed poly(ethylene terephthalate)/synthetic mica nanocomposite sheet and its biaxial deformation behaviour

BACKGROUND: Poly(ethylene terephthalate) (PET) is widely used in the packaging industry. In order to enhance the mechanical and barrier properties, nanoscale fillers are added to PET matrices to form nanocomposites. In the work reported here, a melt‐processed PET/synthetic mica nanocomposite sheet was characterised to determine the effect of the incorporation of synthetic mica on the sheet properties and also to see if these properties are an indicator of subsequent performance under high‐speed, high‐temperature biaxial deformation, typical of processes such as stretch blow moulding. RESULTS: The incorporation of synthetic mica was found to enhance the modulus, particularly above the glass transition temperature, and barrier properties of the extruded sheet and it significantly altered the deformation behaviour of PET under biaxial deformation. The plastic flow of PET during biaxial deformation was found to diminish for the nanocomposites, and strain hardening occurred earlier. CONCLUSION: The modulus and barrier properties of PET were enhanced by the incorporation of synthetic mica. Clay loading also altered the biaxial deformation behaviour of PET. Copyright © 2009 Society of Chemical Industry     

Fabrication of High Performance Fly Ash/Mica/Poly(ether-ether-ketone) Hybrid Composites

This paper deals with the preparation and characterization of poly(ether-ether-ketone) (PEEK) fly ash mica hybrid composites containing filler 5:15, 10:10 and 15:5 fly ash mica combinations loading. The performances and properties of the resulting 20 wt% loading of fly ash mica/PEEK hybrid composites were examined. The resulting hybrid composites of 20 wt% fly ash and mica with varying combinations exhibit the optimum improvement of mechanical properties and dielectric strength. MDSC showed the decrease in the crystallization temperature (Tc) with varying combinations of fly ash and mica. The morphology of fly ash/mica/PEEK hybrid composites was studied by SEM.     

Mechanical and Rheological Properties of Poly(ethylene terephthalate)/ Polypropylene Blends

Poly(ethylene terephthalate) and polypropylene (PET/PP) were compounded and pelletized with a single-screw extruder. Standard ASTM tensile test specimens were made by injection moulding. The blends are stronger and stiffer than the plain PP specimens. The addition of a compatibilizer, EPOLENE E-43, is found to improve the strength and stiffness of the blends at loadings of 50% and 70% PET. At 10% PET loading, E-43 has the opposite effect of slightly reducing the tensile properties. All the blends are more brittle relative to either plain PET or PP. The addition of E-43 results in negligible improvement in the elongation at break. E-43 is also found to be an effective lubricant in improving the processability of the blends. The blends with E-43 added have lower viscosities and less shear-thinning characteristics than those without E-43. © 1997 SCI.     

Structure and Properties of Nanocomposites with a Poly(ethylene terephthalate) Matrix

Polymer nanocomposites based on PET and with an intercalated and fairly dispersed nanostructure have been obtained in the melt state. The intercalation and dispersion levels, as well as the mechanical properties, were studied by varying the chemical nature and amount of the organic modification of the clay, as well as the clay content. The intercalation level of PET into the organoclay galleries was measured by following the increase in the interlayer distance upon mixing. The surfactant content did not influence the intercalation level but an interaction between the polymeric matrix and the surfactant, through a common polar character, led to improved intercalation. The modulus increases observed, and consequently the overall dispersion, almost did not depend on either the amount or the chemical nature of the organic modification of the clay used, suggesting that the parameters leading to a high degree of intercalation differ from those which lead to a high modulus of elasticity and therefore to a high dispersion level. The obtained increases in the modulus of elasticity that reflect the dispersion level were large, attaining a 41% increase with respect to that of the matrix after a 6 wt.‐% clay addition.

     

Synthesis and characterisation of branched and partially crosslinked poly(ethylene terephthalate)

In the present study, a series of branched and partially crosslinked poly(ethylene terephthalate) (PET) samples were prepared by the two‐stage melt polycondensation method, using different amounts of trimethyl trimellitate (TMT) as polyfunctional monomer. The samples were characterised with respect to intrinsic viscosity, density and gel content as well as thermal and mechanical properties. The intrinsic viscosity of the polymers ranged between 0.7 and 1.6 dl g^?1 depending on the concentration of the TMT comonomer. When TMT was used at a concentration 0.625 wt% or higher, gel formation was observed. For the sample containing 1.25 wt% TMT, almost half of the polymer was insoluble in phenol–tetrachloroethane mixture, due to extensive crosslinking. The increase of TMT content resulted in a small decrease of crystallinity attributed to branching and crosslinking, both of which restrict the organisation of the polymer chains in the crystal structure. This was reflected directly in the thermal properties of the polymers prepared. Increasing the TMT content decreased the melting point and the heat of fusion. In contrast, cold crystallization and glass transition temperatures were shifted to higher temperatures. Mechanical properties like tensile strength and elongation at break increased with increasing the content in branching agent. However, crosslinking had a negative effect on elongation at break. Copyright © 2003 Society of Chemical Industry     

Non-isothermal Crystallization of Poly(ethylene terephthalate) with Poly(oxybenzoate-p-trimethylene terephthalate) Copolymer

The influence of a poly(oxybenzoate-p-trimethylene terephthalate) copolymer, designated T64, on the non-isothermal crystallization process of poly(ethylene terephthalate) (PET) was investigated. All samples were prepared by solution blending in a 60/40 by weight phenol/tetrachloroethane solvent at 50°C. The solidification process strongly depended on cooling rate and composition of system. The crystallization rate of blends was estimated by crystallization rate parameter (CRP) and crystallization rate coefficient (CRC). From these results of CRP and CRC, it was predicted that the overall non-isothermal crystallization rate of PET would be accelerated by blending with 1–15 wt% of T64. The acceleration of PET crystallization rate was most pronounced in the PET/T64 blends with 5 wt% T64. The observed changes in crystallization behavior are explained by the effect of the physical state of the copolyester during PET crystallization as well as the amount of copolymer in the blends. An Ozawa plot was used to analyze the data of non-isothermal crystallization. The obvious curvature in the plot indicated that the Ozawa model could not fit the PET/T64 blend system well, and there was an abrupt change in the slope of the Ozawa plot at a critical cooling rate.     

Influence of different functionalized multiwall carbon nanotubes on the mechanical properties of poly(ethylene terephthalate) fibers

Master batches with four different kinds of functionalized multiwall carbon nanotubes (MWCTs) were prepared through the mixing of MWCTs with poly(ethylene terephthalate) (PET) (0.01 : 0.99 w/w) in trifluoroacetic acid/dichloromethane mixed solvents (0.7 : 0.3 v/v) followed by the removal of the solvents in the mixture by flocculation. The results of scanning electron microscopy showed that a good dispersion of MWCTs in PET was achieved. The reinforced fibers were fabricated by the melt spinning of PET chips with small amounts of the master batch and then further postdrawing. The optimal spinning conditions for the reinforcement of fibers were a 0.6-mm spinneret hole and a 250 m/min wind-up speed. Among the four master batches, the fibers obtained from PET/master batch B made by acid-treatment had the highest enhancement of mechanical properties. For a 0.02 wt % loading of acid-treated MWCT, the breaking strength of the PET/master batch B composite fibers increased by 36.9% (from 4.45 to 6.09 cN/dtex), and the initial modulus increased by 41.2% (from 80.7 to 113.9 cN/dtex). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of Poly(ethylene terephthalate)/Poly(amino ether) Blends by means of the Addition of Poly(butylene terephthalate)

Summary: Blends based on poly(ethylene terephthalate), PET, with poly(amino ether) (PAE) contents up to 40% were obtained by the addition of 20% poly(butylene terephthalate) (PBT) to the PET matrix. PBT mixed with PET led to a decrease in the T_m of the matrix that was enough to produce homogeneous blends by mixing in the melt state. Despite the presence of a single peak observed by dynamic‐mechanical analysis, the blends were biphasic, with amorphous phases in which minor amounts of the other component, both reacted and mixed, were present. This presence of minor components gave a fine morphology and significant adhesion that, together with the higher orientation of PAE in the blends, produced blends with a clear synergism in the modulus of elasticity, notched impact strength similar to that of the neat components, and high ductility up to 30% PAE.

Young's modulus of the PET‐PBT/PAE blends.     

Preparation and properties of poly(ethylene terephthalate)/inorganic whiskers composites

To improve the crystallization and mechanical properties of poly(ethylene terephthalate) (PET), in this work, PET/SiO₂‐MgO‐CaO whiskers composites were prepared via in situ polymerization. The morphology, crystallization, and mechanical properties of the prepared composites were investigated. It was found that inorganic whiskers could be easily dispersed in PET matrix, as demonstrated by SEM and PLM. DSC and PLM observation indicated a strong nucleation capability of inorganic whiskers for PET. Mechanical analysis results showed that the glass transition temperature, tensile strength, and modulus of the composites were greatly improved. A possible chemical bonding between PET chains and the surface of whiskers was observed by FTIR, TGA, and sedimentation experiment. It could be the main reason for the good dispersion and improved properties of the prepared composites. This work is important for the application of PET due to the low cost but high reinforcing efficiency of this inorganic whisker. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(butylene terephthalate)/poly(ethylene glycol) blends with compatibilizers

Polymer blend systems offer a versatile approach for tailoring the properties of polymer materials for specific applications. In this study, we investigated the compatibility of polybutylene terephthalate (PBT) and poly(ethylene glycol) (PEG) blends processed using a twin-screw extruder, with the aim of enhancing their compatibility. Phthalic anhydride (PAn) and phthalic acid (PAc) were used as potential compatibilizers at different concentrations to improve interfacial interactions between PBT and PEG. Blend morphologies were characterized using scanning electron microscopy, which revealed improved interfacial compatibility and reduced phase separation with the incorporation of small amounts of PAn and PAc. Differential scanning calorimetry analysis indicated changes in the melting temperature (T_m) and glass transition temperature (T_g) of the blends owing to the compatibilizing effects of PAn and PAc. Dynamic mechanical analysis further corroborated the influence of the compatibilizers on the T_g and viscoelastic behavior. Thermogravimetric analysis demonstrated enhanced thermal stability with the addition of either PAn or PAc. Rheological measurements indicated an increase in complex viscosity with increasing compatibilizer content, indicating improved compatibility. The degradation point (T_d) of PBT/PEG blend increased from 158 to 200 and 319°C with the incorporation of 5 phr PAn and 2 phr PAc, respectively. Mechanical properties, including tensile strength, Young's modulus, and Izod impact strength, were evaluated. For instance, the tensile strength of PBT/PEG blend was enhanced from 43.5 to 48.7 and 49.7 MPa by incorporating 5 phr PAn and 2 phr PAc, respectively. However, the impact strength of PBT/PEG blend increased from 3.0 to 4.3 and 4.2 kJ/m² with the addition of 1 phr PAn and 1 phr PAc, respectively. The findings demonstrated that adding 5 phr PAn or 2 phr PAc to the PBT/PEG blends was advantageous, achieving a harmony of performance benefits and compromises. Rheological observations contributed significantly to the mechanical and thermal properties. Overall, the study highlights the significance of utilizing PAn and PAc as effective compatibilizers for enhancing the properties of PBT/PEG blends, making them potential candidates for various applications.     

New hybrid system: Poly(ethylene glycol) hydrogel with covalently bonded pegylated nanotubes

Hydrogels containing carbon nanotubes (CNTs) are expected to be promising conjugates because they might show a synergic combination of properties from both materials. Most of the hybrid materials containing CNTs only entrap them physically, and the covalent attachment has not been properly addressed yet. In this study, single‐walled carbon nanotubes (SWNTs) were successfully incorporated into a poly(ethylene glycol) (PEG) hydrogel by covalent bonds to form a hybrid material. For this purpose, SWNTs were functionalized with poly(ethylene glycol) methacrylate (PEGMA) to obtain water‐soluble pegylated SWNTs (SWNT–PEGMA). These functionalized SWNTs were covalently bonded through their PEG moieties to a PEG hydrogel. The hybrid network was obtained from the crosslinking reaction of poly(ethylene glycol) diacrylate prepolymer and the SWNT–PEGMA by dual photo‐UV and thermal initiations. The mechanical and swelling properties of the new hybrid material were studied. In addition, the material and lixiviates were analyzed to elucidate any kind of SWNT release and to evaluate a possible in vitro cytotoxic effect. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of multi‐walled carbon nanotube/poly(ethylene terephthalate) nanoweb

Multi‐walled carbon nanotube (MWCNT)/Poly(ethylene terephthalate) (PET) nanowebs were obtained by electrospinning. For uniform dispersion of MWCNTs in PET solution, MWCNTs were functionalized by acid treatment. Introduction of carboxyl groups onto the surface of MWCNTs was examined by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) analysis. MWCNTs were added into 22 wt % PET solution in the ratio of 1, 2, 3 wt % to PET. The morphology of MWCNT/PET nanoweb was observed using field emission‐scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). The nanofiber diameter decreased with increasing MWCNT concentration. The distribution of the nanofiber diameters showed a bi‐modal shape when MWCNTs were added. Thermal and tensile properties of electrospun MWCNT/PET nanowebs were examined using a differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA) and etc. Tensile strength, tensile modulus, thermal stability, and the degree of crystallinity increased with increasing MWCNT concentration. In contrast, elongation at break and cold crystallization temperature showed a contrary tendency. Electric conductivities of the MWCNT/PET nanowebs were in the electrostatic dissipation range. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Methanolysis of Poly（ethylene terephthalate）in Supercritical Phase

1 INTRODUCTIONPoly(ethylene terephthalate), commonly known as PET polyester, is extensively used for making synthetic fibers and package containers. The volume of PET consumed is rising by year, and thus the chemical recycling and reuse of waste PET are drawing much attention for the preservation of resources and the protection of environment. Through chemical recycling, waste PET is depolymerized into its valuable monomers such as dimethyl terephthalate (DMT), bis (hydroxyethyl) ter…     

Synthesis and Characterisation of Branched Poly(ethylene terephthalate)

Branched poly(ethylene terephthalate)s (PET) were synthesised with a variety of molar masses and with a large range of degree of branching by introduction of mono-, tri-(glycerol) and tetra-functional (pentaerythritol) comonomers to dimethyl terephthalate and ethylene glycol. The monofunctional alcohols, dodecanol and benzyl alcohol, were used as terminating agents to minimise gelation. The effect of various reaction parameters, such as percentage glycerol or pentaerythritol and polymerisation time, on limiting viscosity number [η] and weight average molar mass (M_w) were investigated. The thermal behaviour of branched PET was studied by differential scanning calorimetry; all samples showed a characteristic double endothermic melting peak and the glass transition temperature was not observed. Some branched PETs were subjected to solid-state polymerisation to increase the molar mass of previously prepared branched polymers. The solid-state polymerisation technique showed that the process not only promoted the molar mass but, more importantly, it increased the crystallinity of the polymer. Overall, the solid-state reaction rate was governed by initial molar mass, crystallinity, reaction temperature and time. © of SCI.