Melt Foamability of Poly(ethylene terephthalate)/Clay Nanocomposites Prepared by Extrusion Blending in the Presence of Pyromellitic Dianhydride

Abstract

Exfoliated poly(ethylene terephthalate) (PET)/organoclay nanocomposites were prepared by extrusion blending method with different clay contents and molecular weights of raw PET. Pyromellitic dianhydride (PMDA) was extruded, together with PET and clay, to introduce long-chain branching to PET backbone and delaminate the clay layers. Although the molecular weights and viscoelastic properties of nanocomposites were much lower than those of foamable PMDA-modified PET, the melt foamability of nanocomposites was significantly improved by the well-dispersed clays due to the heterogeneous nucleation effect, enhanced nonisothermal crystallization rate, and so on. Foaming temperature windows with a width of 20−60°C were explored for PET/clay nanocomposites with intrinsic viscosities of 0.67−0.94 dL/g, in which nanocomposites foams with cell diameters of 29−53 μm, cell densities of 6.5 × 10 7 −6.9 × 10 8 cells/cm 3 , and expansion ratio of 10−50 could be controllably produced using supercritical CO 2 as a blowing agent.

Preparation, structure, and properties of poly(ethyleneoxide)/lignin composites used for UV absorption

“…Nofar et al . believe that nanocomposite technology is a simple and effective method to prepare better polymer foams by increasing the elongational viscosity, melt strength, and nucleation efficiency in the polymer . In the above discussion, we proved that in the PEO/Lg composite, the Lg particles could act as a heterogeneous nucleating agent and also enhance the melt strength of the composite.…”

High‐melt‐elasticity poly(ethylene terephthalate) produced by reactive extrusion with a multi‐functional epoxide for foaming

“…The material used in this study was a bottle‐grade PET (BG80) with an intrinsic viscosity (IV) of 0.8 dL/g, which was purchased from Sinopec Yizheng Chemical Fibre Co., Ltd., (Yizheng, China). The carboxyl content of this resin was measured to be equal to 21 mmol/kg and its number‐average molar mass is 26,300 g/mol . The hydroxyl content was calculated equal to 55 mmol/kg according to the Berkowitz equation, .…”

“…The carboxyl content CC 0 of this resin was measured to be equal to 21 mmol/kg and its number-average molar mass M n is 26,300 g/ mol. 35 The hydroxyl content CH 0 was calculated equal to 55 mmol/kg according to the Berkowitz equation, 6 M n 52; 000; 000=ðCC 0 1CH 0 Þ. The two modifiers are ADR and PMDA, they were supplied by BASF (Germany) and Sinopharm Chemical Reagent Company (China) respectively.…”

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

“…To qualitatively investigate promotion of PTFE fibrils in the TPEE crystallization kinetics, a modified Avrami analysis was employed, as described in earlier works [39] and the region calculated ranged from 3% to 50% in relative crystallinity to avoid the influence of epiphytic crystal growth. The crystallization kinetic parameters (k' and n), together with the enthalpy of crystallization (ΔHc), the crystallization onset temperature (Tc, onset), the crystallization temperature (Tc), the melting temperature (Tm) and the half-crystallization time (t1/2, defined as when the relative crystallinity reaches 50%) are listed in Table 2.…”