Thermal and mechanical properties of poly(ethylene terephthalate)/lamellar zirconium phosphate nanocomposites

Abstract

ABSTRACT:The preparation of nanocomposites of poly (ethylene terephthalate) (PET) and lamellar zirconium phosphorous compounds by melt extrusion was investigated. Two types of zirconium phosphorous compounds were synthesized by the direct precipitation reaction method: a-zirconium bis(monohydrogen orthophosphate) monohydrate (ZrP) and organic-inorganic hybrid layered zirconium phenylphosphonate (ZrPP). Composites containing 2 and 5 wt % ZrP and ZrPP were prepared in a twin-screw extruder and specimens were obtained by injection molding. The extent of dispersion of the layered filler in the composite matrix was investigated by X-ray diffraction and transmission electron microscopy (TEM). The crystallization and thermal properties were analyzed by differential scanning calorimetry and thermogravimetry, and the mechanical properties were evaluated by tensile tests. Whereas ZrP-containing composites showe characteristic diffraction peaks at 2y 11.78 (d ¼ 7.54 Å ), indicative of no delamination, ZrPP showed practically no low-angle diffraction peak at 2y 5.58 (d ¼ 15.24 Å ), indicating loss of the layered order. TEM images of ZrPP particles indicated the formation of an intercalated/partially delaminated nanocomposite. The behavior was attributed to the higher affinity of the polyester with phenyl groups on the platelet surface of ZrPP. In both cases, the addition of the fillers increased the crystallization rate and the modulus.

Properties of poly(lactic acid) nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

“…To improve the physical properties of PLA, especially in terms of thermomechanical stability, addition of different fillers (nanoparticles) in PLA was explored [2,[9][10][11]. Most of the literature regarding nanocomposites is devoted to lamellar layered silicates, in particular organically modified montmorillonites due to their ability to significantly enhance several polymer physical properties as compared to unmodified layered silicate clays, including gas barrier, flame retardancy, thermal stability and influence on the polymer biodegradation rate [2,[12][13][14]; however, needle like phyllosilicates (sepiolites) and zirconium phosphate are also reported in literature [15][16][17][18][19][20][21]. Sepiolite is a layered hydrated magnesium silicate characterized by a needle like morphology based on alternated blocks of tunnels in the fibre direction [16] and very high surface area (BET 374±7 m 2 /g) [23] as compared to layered phyllosilicates (BET 82±1 m 2 /g) [23,24].…”

“…Based on the few papers on PLA, Poly (#-caprolactone) (PCL), PP and Poly (butylene terephthalate) (PBT) [15,16], the possibility of an unmodified sepiolite to well disperse in polymers by melt blending was evidenced and mainly attributed to the large concentration of surface silanols, spaced every 0,5 nm along the length of sepiolite needle [30][31][32], that are easily available for coupling reactions with local polarity on polymer chains. Zirconium bis(monohydrogen orthophosphate) monohydrate, ($-Zr(HPO 4 ) 2 (H 2 O) ($-ZrP)), has a layered structure with many interesting properties, such as high density of grafted organic modifiers, high thermal stability [33], possible achievement of large aspect ratios, high elastic modulus and the potential to delaminate and become intercalated within the polymer [17,18]. PLA/zirconium phosphate composites has been studied and showed intumescent flame-retardant properties [34].…”

Preparation and characterisation of a novel fire retardant PET/α-zirconium phosphate nanocomposite

“…[20]. Zirconium bis(monohydrogen orthophosphate) monohydrate, (-Zr(HPO 4 ) 2 ·H 2 O) (-ZrP), is a layered structure material with many interesting features, such as high ion-exchange capacity, thermal and chemical stability [22], 3 catalytic activity, ionic conductivity, and the potential to delaminate and become intercalated within the polymer [23]. Many of these properties are common to natural layered nanofillers such as montmorillonite, but -ZrP has a higher ion exchange capacity [24], and has different elements in its structure.…”

“…Many of these properties are common to natural layered nanofillers such as montmorillonite, but -ZrP has a higher ion exchange capacity [24], and has different elements in its structure. However, only a few studies have been reported on layered zirconium phosphate polymer nanocomposites, such as preparation of epoxy-α-ZrP [24][25][26][27] nanocomposites, polyethyleneimine-γ-ZrP nanocomposites [28] and poly (ethylene terephthalate)/lamellar zirconium phosphate nanocomposites [23]. Furthermore, the foci of these studies was the synthesis and the improvement of thermal or mechanical properties.…”

High density polyethylene and zirconium phosphate nanocomposites

“…The system was kept under agitation and reflux at 110 °C, for 24 hours. After that, the resulting material was centrifuged (3400 rpm for 30 min) and washed successively with deionized water in order to obtain neutral pH and absence of chloride [16][17][18] . The resulting solid was placed in a freezer at -80 °C for 24 hours and then submitted to lyophilization for 4 days.…”