Morphological Consequences of Interchange Reactions during Solid State Polymerization in Oriented Polymers

Almonacil, Celine; Desai, Prashant; Abhiraman, A. S.

doi:10.1021/ma9920339

Cited by 10 publications

(8 citation statements)

References 54 publications

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“…Solid state polymerization (SSP) is an established procedure to increase the molecular weight (MW) of polyesters [1] (e.g., poly (ethylene terephthalate) (PET) [2], poly (butylene terphthalate) [3]), polycarbonates [4], polyamides [5] such as nylon [6, 7], etc. During SSP, the polymer is heated up to temperature ranges which enhance the polycondensation reaction, usually up to 20–50°C below the melting point ( T m ).…”

Section: Introductionmentioning

confidence: 99%

High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization

Katiyar

Nanavati

2011

Polymer Composites

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We propose here, a novel technique to synthesize high molecular weight (MW) poly (L-lactic acid)-clay nanocomposite (PLACN), via solid state polymerization (SSP). We synthesize prepolymer of PLACN (pre-PLACN) from both, L-lactic acid and L-lactide, as starting materials. Synthesis of pre-PLACN from L-lactic acid is carried out via in situ melt polycondensation (MP) of L-lactic acid oligomer, followed by SSP, to achieve high MW PLACN (M w $ 138,000 Da). In case of L-lactide as the starting material, we prepare L-lactide-clay intercalated mixture which yields moderate MW pre-PLACN during subsequent ring opening polymerization (ROP). Interestingly, ROP is performed by using hydroxyl functionalized ternary catalyst system (L-lactide-Sn(II) octoate-oligo (L-lactic acid) complex), which provides the terminal hydroxyl end-groups, required for step-growth SSP. Pre-PLACN MW is now increased to M w $ 127,000 Da, by the subsequent SSP process. 1 H NMR analyses confirm that these endgroups, are indeed consumed during SSP. During SSP, the PLACN also achieves up to 90% crystallinity, which may be due to the synchronization of the slow stepgrowth SSP of poly(L-lactic acid) (PLA) with the crystallization kinetics. Optical purity of PLACNs is similar to that of neat PLA, whereas the thermal stability of PLACNs is significantly superior. As evidenced by wideangle X-ray scattering/small-angle X-ray scattering analyses and in line with the literature, both, intercalated and exfoliated PLACN morphologies, have been synthesized, by suitable selection of clays. We also verify the correlation between the PLA semicrystalline morphology and the PLACN morphology, which is consistent with those of PLACN synthesized by other techniques. POLYM. COM-POS., 32:497-

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Section: Introductionmentioning

confidence: 99%

High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization

Katiyar

Nanavati

2011

Polymer Composites

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“…The pertinent reactions, such as amine-amide and acid-amide interchange, are considered to play a fundamental role during SSP by providing a mechanism for end group functionality to migrate and thus facilitating polymerization. [25] However, they induce morphological changes in the polymer structure, through creating loops and bridges and therefore producing a structural reorganization of the amorphous and crystalline regions of the polymer.…”

Section: Solid-state Polyamidationmentioning

confidence: 99%

Catalyzed Solid‐State Polyamidation

Vouyiouka

Papaspyrides

Pfaendner³

2006

Macro Materials & Eng

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Summary: The current study is focused on key experiments on catalyzed SSP, examining the effect of selected phosphonates on the overall process rate. Catalyst incorporation was achieved through melt blending in a single screw extruder, providing a suitable and homogenous starting material for the reaction in the solid phase. More specifically, the post‐polycondensation runs were performed in a fixed bed reactor under flowing nitrogen at 160 and 200 °C. The additives used were found to catalyze the reaction in the solid phase, resulting even in tripling the solution relative viscosity after 4 h of SSP. Differences in the catalytic performance of the added materials were observed and correlated to the catalysts properties and morphology. An indicative potential catalysis mechanism is suggested, in which reactivity enhancement through partial attachment of the phosphorus compounds on the polyamide chain is the key step. Finally, the kinetics of the process were examined based on a power‐law rate expression, which was further modified so as to relate the apparent SSP rate constant with the phosphorus concentration.SSP rate constants as a function of catalyst content.magnified imageSSP rate constants as a function of catalyst content.

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“…Monte Carlo method can simulate the intermolecular reaction with arbitrary initial distribution and obtain the relationship between MWD and real reaction time by combining macro‐kinetics with microcosmic molecular reaction 14, 16–22. Litmanovich et al14 developed an algorithm to generate an ensemble of statistical multiblock AB copolymer chains via a polymer‐analogous reaction with acceleration.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of molecular weight distribution and copolymer composition in transamidation reaction of polyamides

Yao

Sun

Wang

et al. 2012

J of Applied Polymer Sci

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Melt mixing of polyamides results in exchange reaction and generation of copolymers. In this work, Monte Carlo method is used to simulate the time evolution of molecular weight distribution (MWD) and copolymer composition during the exchange reaction process between polyamides with AA and BC structure. The influences of initial composition and molecular weight have been investigated. Decrease in the difference between the average molecular weight of two kinds of polyamides results in faster approach of the MWD toward Flory's dis-tribution and higher probability of producing copolymers. When the ratio between the numbers of initial molecules of two homopolymers is increased, the number of generated copolymers is reduced and the wider MWD is obtained.

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Morphological Consequences of Interchange Reactions during Solid State Polymerization in Oriented Polymers

Cited by 10 publications

References 54 publications

High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization

High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization

Catalyzed Solid‐State Polyamidation

Monte Carlo simulation of molecular weight distribution and copolymer composition in transamidation reaction of polyamides

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