Properties of Poly(ethylene terephthalate)/Layered Silicate Nanocomposites Prepared by Two-Step Polymerization Procedure

Abstract

ABSTRACT:Intercalated nanocomposites of poly(ethylene terephthalate) (PET) and layered silicate (ME) were prepared by a two-step polymerization process: a melt polymerization of bis(2-hydroxyethyl)terephthalate and a subsequent solid-state polymerization. Two kinds of cationic surfactants, dodecyltriphenylphosphonium bromide (C 12 TP) and 10-[3,5-bis(methoxycarbonyl)phenoxy]decyltriphenylphosphonium bromide (IP10TP) were employed as compatibilizers. The dispersibility of ME in PET was investigated by X-Ray diffraction analysis and optical polarization microscopy. The thermal and dynamic mechanical behavior of the nanocomposites was compared with that of pure PET and a PET/ME composite. By utilizing IP10TP as the compatibilizer, better dispersion of ME into the PET matrix could be achieved. The obtained PET/IP10TP/ME nanocomposite showed a higher tensile storage modulus compared with those of pure PET, PET/ME, and PET/C 12 TP/ME, especially in the temperature range above the glass transition temperature.KEY WORDS Nanocomposites / Poly(ethylene terephthalate) / Layered Silicates / Compatibilizer / Dynamic Mechanical Property / Much attention has been paid to polymer/layered silicate nanocomposites because remarkable improvements can be expected in mechanical, thermal, and physicochemical properties over their base polymers or conventional composites. 1-4 Development of poly(ethylene terephthalate) (PET)/layered silicate nanocomposites is highly desired because of their practical importance. [5][6][7] We have recently reported the preparation of PET/expandable fluorine mica (ME) nanocomposites via an in-situ polymerization method utilizing a novel reactive compatibilizer, 10-[3,5-bis(methoxycarbonyl)phenoxy]decyltriphenylphosphonium bromide (IP10TP, Scheme 1). 8 The obtained nanocomposites showed a high flexural modulus compared with that of pure PET. However, the molecular weight of PET in the nanocomposites was found to be low for practical applications, probably due to the high viscosity during the melt polymerization. A solid-state polymerization (SSP) process can be applied to increase the average molecular weight of PET without being affected by the viscosity of the reactants. [9][10][11] In the SSP process, the crystallized PET prepolymer is heated at a temperature below the crystalline melting point (T m ) but well-above the glass transition temperature (T g ) under a flow of inert gas or under vacuum. The hydroxyethyl end groups of the PET prepolymer are considered to be concentrated into the amorphous region during the crystallization process. The transesterification reaction between the chain ends leads to the high-molecular-weight PET.In the present study, we applied the SSP process to prepare PET/IP10TP/ME nanocomposites with a suitable molecular weight. A PET/ME composite with dodecyltriphenylphosphonium bromide (C 12 TP, Scheme 1) was prepared in order to determine the effect of the functional groups of IP10TP on the final properties of the PET nanocomposites. Pure PET and a PET/ME composite without ...

Recycled PET nanocomposites improved by silanization of organoclays

“…16,17 In the case of PET/clay systems, the first two techniques were successfully tested. [18][19][20][21][22][23][24][25][26][27][28] The melt mixing process is technologically much more interesting; nevertheless, satisfactory results with PET have not been achieved. 29,30,31 Despite sensitivity of melt rheology to changes in structure of the dispersed nanoparticles in the matrix, rheological experiments have been so far rarely used in investigation and characterization of polymer nanocomposites.…”

Spinning and properties of poly(ethylene terephthalate)/organomontmorillonite nanocomposite fibers

“…Exchangeable metal ions existing in the interlayer space neutralize those negative charges, distributing in the surface of layers. Polymer/layered silicate nanocomposites can be prepared by in situ polymerization,6, 9, 11–14 melt blending,2, 15–17 or solution blending18 after ion exchange of MMT with organic cations, which leads to expanding of interlayer distance and modifying of surface polarity of clay layers. Two kinds of nanocomposites, intercalated or exfoliated, will form according to the dispersion state of clay layers in polymer matrix.…”

“…Usually, copolymerization and blending with other polymers are effective ways in the chemical or physical modification of PET, and a series of new materials with better performance compared with PET was yielded in the last a few years 19–22. Recently, in light of success in research of some polymer/clay nanocomposites, preparation of PET/clay nanocomposite has become another popular method to improve the performance of PET,9, 13, 14, 16, 23, 24 although molecular mass degradation and alkyl ammonium degradation during processing of some polymer/layered silicate nanocomposites have both been observed,25–27 and those surfactants with higher thermal stability were widely used 13, 14, 16, 28–30. Despite the great effort in this area over the past a few years, challenges still remain to be solved to produce PET/layered silicate nanocomposite of exfoliated style, especially of commercial quality.…”

Development of active barrier systems for poly(ethylene terephthalate)

“…Various methods have been used to reduce the inherent oxygen permeability of PET as a passive (nonreactive) polymer. These include structure and morphology manipulation,1–4 copolymerization5–9, and the use of nanocomposites 10–21. Such strategies have provided limited levels of barrier property improvement.…”