Chain extension of poly(butylene terephthalate) by reactive extrusion

Guo, Baohua; Chan, Chi‐Ming

doi:10.1002/(sici)1097-4628(19990314)71:11<1827::aid-app13>3.0.co;2-7

Cited by 57 publications

(68 citation statements)

References 15 publications

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“…Additionally, isocyanurates can arise from trimerization of isocyanate as well as from the reaction of allophanate and excess isocyanate. These secondary reactions lead to branching and finally to crosslinking of the polymer [27,33,36,39,40,42]. The kinetic rate constants of allophanate, urea and isocyanurate formation are much smaller than the ones of urethane and amide formation [39], and it is well known that these reactions are only favored at higher concentrations of isocyanate groups.…”

Section: Resultsmentioning

confidence: 99%

“…Another reason for brittleness is a low molecular weight, which can be caused by hydrolysis if moisture is present during the ROP. Moreover, water can negatively affect the catalyst, which also leads to a lower molecular weight [9,27]. Several researchers have addressed this problem by copolymerizing CBT with poly (ethylene-co-vinyl acetate) [28], poly(vinyl butyral) [29], !-caprolactone [30] and polycaprolactone [4,31].…”

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confidence: 99%

“…Of the available groups of chain extenders for polyesters, isocyanates (NCO) are promising. They show higher reactivity than epoxides and readily react at moderate temperatures with active hydrogen containing compounds [27,32,33]. The reaction can be promoted by metals in the form of organometallics and/or salts of organic acids.…”

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confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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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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“…In the literature, numerous examples are given that describe the utilization of reactive bifunctional compounds as chain extenders and coupling agents, such as diisocyanates, [1][2][3] bisoxazolines, [4][5][6][7][8][9][10] bisepoxides, [11][12][13][14] bislactamates, [15][16][17] and bisoxazolones. [18,19] In the case of polymers that contain different reactive groups, a combination of coupling agents has been applied.…”

Section: Feature Articlementioning

confidence: 99%

Introduction of a New Coupling Agent for Selective Coupling of Hydroxy and Amino Group‐Containing Polymers

Jakisch

Komber

Böhme

2007

Macro Materials & Eng

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IntroductionMulticomponent mixtures of polycondensates are widely spread in polymer chemistry. In order to achieve good adhesion and compatibility, covalent links between the components are desirable. It is evident that such linkages may be formed by the same reactions that usually occur during the synthesis of polycondensates. These are reactions of the terminal groups among each other but also transreactions between the terminal groups and the linking groups of polycondensates, such as, for example, transesterification and transamidation. In blends of condensates, such reactions result in in-situ formation of block copolymers in the interface between the components.In order to achieve high degrees of conversion, severe conditions such as good vacuum, high reaction temperatures, and long reaction times are demanded. In addition, suitable catalysts and effective mixing have to be applied. Under such conditions, undesired side reactions and by-products may complicate process control and limit the final product properties. This especially applies to the preparation of defined multi-block copolymers. Transreactions that occur during the entire process make it practically impossible to control the length of the Feature ArticleA new bifunctional coupling agent with an oxazinone and a lactamate group is synthesized. It is shown by means of model reactions that in the presence of aliphatic hydroxy compounds the reaction of the coupling agent is highly selective. At 220 8C, a conversion of the lactamate group of about 90% is observed under elimination of lactam. In a second reaction the oxazinone group is converted with an aliphatic amino compound. This high selectivity is utilized in the synthesis of segmented polyester/polyamide block copolymers by sequential conversion of the coupling agent with hydroxyterminated polyesters [poly(butylene terephthalate) (PBT) and polycaprolactone (PCL)] and aminoterminated polyamide 12 (PA12) under the conditions of reactive extrusion. In the case of the PA12/PBT block copolymer, ductile behavior is observed, whereas the PA12/PCL block copolymer shows elastic properties. Both polymers are phase separated on the nanometer-scale, as evidenced by AFM and SEM. The thermal behavior of the polymers is affected by the influence of the individual blocks.

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“…These rejects are almost always deposited in land wastes, causing pollution or several others environmental problems 3,5,6 . Many studies have been carried out with the use of chain extenders to recover properties of low molecular weight PET [7][8][9][10][11][12][13][14] . Chemical compounds such as anhydride and organophosphorus are some agents used as chain extender for PET.…”

Section: Introductionmentioning

confidence: 99%

Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer

Bimestre

Saron

2012

Mat. Res.

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Poly(ethylene tereftalate) (PET) is a polymer highly susceptible to the hydrolytic reactions that occur during applications and mainly in thermomechanical processing. These reactions lead to the decrease of molecular weight of the polymer, limiting the recycling number of the material. The reactive extrusion of the PET in presence of chain extenders is an alternative to recover mechanical and rheological properties that were depreciated by the polymer degradation. In this study, PET wastes from nonwoven fabrics production were extruded in presence of the secondary stabilizer Irgafos 126 (IRG) on variable concentrations. The results showed that Irgafos 126 increased molecular weight, decreased crystallinity and changed processing behavior of the PET, similarly to the effects produced by the well-known chain extender pyromellitic dianhydride (PMDA), showing that the secondary stabilizer Irgafos 126 can also act as a chain extender for the PET.

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Chain extension of poly(butylene terephthalate) by reactive extrusion

Cited by 57 publications

References 15 publications

Isocyanate toughened pCBT: Reactive blending and tensile properties

Isocyanate toughened pCBT: Reactive blending and tensile properties

Introduction of a New Coupling Agent for Selective Coupling of Hydroxy and Amino Group‐Containing Polymers

Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer

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