Chain extension and branching of poly(ethylene terephthalate) (PET) with di- and multifunctional epoxy or isocyanate additives: An experimental and modelling study

Raffa, Patrizio; Coltelli, Maria Beatrice; Savi, Stefania; Bianchi, Sabrina; Castelvetro, Valter

doi:10.1016/j.reactfunctpolym.2011.10.007

Cited by 129 publications

(124 citation statements)

References 28 publications

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“…The development of crystalline structure in modified PLA-PBAT blends is effectively hindered. This can be related to the higher branching density, as demonstrated for PET [31], despite it exhibits a slightly increase of the cold crystallization compared to the unmodified one. Representative curves of DMTA recording tanδ and logE' for the neat and modified blown PLA films are shown in Figure 17.…”

Section: Thermo-mechanical and Crystalline Properties Of The Blown Filmsmentioning

confidence: 78%

Biopolymer Blends Based on Poly (lactic acid): Shear and Elongation Rheology/Structure/Blowing Process Relationships

2015

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This study was dedicated to the blown film extrusion of poly(lactic acid), which mainly presents poor shear and elongation viscosities, and its blends. In order to enhance its melt strength, two main routes were selected (i) a structural modification through chain extension and branching mechanisms by adding a reactive multifunctional epoxide (named Joncryl) and (ii) blending with poly(butylene adipate-co-terephtalate), named PBAT in presence (or not) of Joncryl. The effects of the reactive agent on the shear and elongation rheology, morphological, and interfacial properties of the blends were systematically investigated. A decrease of the interfacial tension has been also demonstrated according to the deformed drop retraction method (DDRM). Hence, the role of Joncryl as a compatibilizer was highlighted. Consequently, finer morphology of the dispersed phase was obtained. Furthermore, the impact of the two modification routes on the blown film extrusion ability of PLA has been studied. Based on the improved shear and elongational rheological properties, a great enlargement of the blowing processing window of PLA modified with Joncryl was demonstrated. Indeed, with the addition of Joncryl into OPEN ACCESSPolymers 2015, 7 940 PLA-PBAT blends, a reduction of the instability defects has been detected. Finally, the induced crystalline structure and the thermo-mechanical properties of blown films were shown to be improved.

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Section: Thermo-mechanical and Crystalline Properties Of The Blown Filmsmentioning

confidence: 78%

Biopolymer Blends Based on Poly (lactic acid): Shear and Elongation Rheology/Structure/Blowing Process Relationships

2015

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“…This suggests that an equilibrium was reached and all blends, regardless of their isocyanate content, exhibited a similar molecular weight. Raffa et al [32] came to a similar conclusion working with recycled PET and its chain extension with diand multifunctional isocyanates. They found a plateau value of both molecular weight and melt viscosity above a threshold amount of isocyanate and ascribed this stationary condition to a mutual compensation of chain extension and degradation processes.…”

Section: Torque Versus Time Measurementsmentioning

confidence: 69%

“…The crystallinity was most effectively decreased (about 7%) when 0.75 wt% PMDI was used. Torres et al [33], Zhang and coworkers [43] and Raffa et al [32] modified recycled PET with di-and polyfunctional isocyanates and observed a similar tendency. This depression is due to the amide and urethane groups which form in the isocyanate reaction.…”

Section: Thermal Propertiesmentioning

confidence: 72%

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Isocyanate toughened pCBT: Reactive blending and tensile properties

Abt¹,

Ilarduya²,

Bou³

et al. 2013

Express Polym. Lett.

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The in situ ring-opening polymerization of cyclic butylene terephthalate oligomers is a promising route to replace thermosetting polymers in composites and has become of great interest. CBT oligomers melt at low temperatures (120-160ºC) and exhibit a water-like viscosity prior to polymerization. Due to this very low initial viscosity, fiber reinforcements can be readily impregnated. After impregnation, the molten CBT oligomers quickly polymerize in an entropically driven, athermal ring-opening polymerization (ROP) without releasing volatile organic compounds. This process yields pCBT, a thermoplastic polyester with high molecular weight [1][2][3]. So far, continuous fiber reinforced composites made from CBT and glass fibers [3][4][5][6][7][8], basalt fibers [9], and carbon fibers [10][11][12][13] have been reported. Moreover, a hydrogenated nitrile rubber (HNBR) was modified with CBT and the HNBR/CBT hybrids exhibited improved mechanical and triblogical properties compared to pristine HNBR [14]. CBT has also been extensively used in nanocomposites due to the low melt viscosity prior to ROP which is advantageous for a good dispersion of the reinforcement. Nanocomposites with nanosilica [15], multiwalled carbon nanotubes [16][17][18][19] Abstract. Cyclic butylene terephthalate oligomers (CBT) were reacted in a ring-opening polymerization with three types of isocyanates: a bifunctional aromatic type, a bifunctional aliphatic type and a polymeric aromatic isocyanate. All reactions took place in a batch mixer. The use of 0.5 to 1 wt% isocyanate led to a dramatic increase in elongation at break of polymerized cyclic butylene terephthalate (pCBT), from 8 to above 100%. The stiffness and strength of the modified pCBT, however, were found to slightly decrease. Proton nuclear magnetic resonance (NMR) analysis shows that the formation of thermally stable amide groups is the dominant chain extension reaction mechanism. Gel content measurements suggest a linear structure for samples containing bifunctional isocyanates while pCBT modified with polyfunctional isocyanate exhibited some gel formation at higher isocyanate content. Melting and crystallization temperatures as well as degree of crystallinity were found to decrease with increasing isocyanate content. No phase separation was detected by scanning electron microscopy (SEM) analysis. Moreover, a high degree of polymerization is deduced due to the absence of CBT oligomer crystals.

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“…Phosphites react with hydroxyl and carboxyl end groups of PET to diminish the possibility of their reaction via hydrolysis. They can also reduce the hydroperoxides to alcohol in polyolefins [3][4][5][6] according to the following reaction:…”

Section: Introductionmentioning

confidence: 99%

Rheological and mechanical properties of recycled poly(ethylene terephtalate)/high density polyethylene blends

Guessoum

Medjdoub

Nekkaa

et al. 2013

MATEC Web of Conferences

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Abstract. Triphenylphosphite (TPP) has been used as a chain extender to regenerate polyethylene terephtalate (PET) and high density polyethylene (HDPE) wastes and to improve the properties of PET/HDPE system based on recycled materials. TPP incorporation in PET and HDPE showed a noticeable increase of the torque as a function of the mixing time and proved that the degradation reactions are considerably decreased. In the case of PET/ HDPE blends, the increase of the torque was strongly dependent on the composition of the homopolymers and on the time of mixing. TPP incorporation contributed to significant variations of the rheological and mechanical properties of the regenerated PET and HDPE and their blends.

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Chain extension and branching of poly(ethylene terephthalate) (PET) with di- and multifunctional epoxy or isocyanate additives: An experimental and modelling study

Cited by 129 publications

References 28 publications

Biopolymer Blends Based on Poly (lactic acid): Shear and Elongation Rheology/Structure/Blowing Process Relationships

Biopolymer Blends Based on Poly (lactic acid): Shear and Elongation Rheology/Structure/Blowing Process Relationships

Isocyanate toughened pCBT: Reactive blending and tensile properties

Rheological and mechanical properties of recycled poly(ethylene terephtalate)/high density polyethylene blends

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