Poly(butylene terephthalate) polycarbonate transesterification: monitoring its progress with Fourier transform Raman spectroscopy

Pellow-Jarman, Martin V.; Hendra, P. J.; Hetem, M.J.J.

doi:10.1016/0584-8539(95)01472-3

Cited by 9 publications

(4 citation statements)

References 5 publications

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“…The peaks in a Raman spectrogram correspond to fundamental transitions and hence provide precise chemical information. FT‐Raman spectroscopy has been used in numerous esterification studies to, for example, investigate polyester structure,11 monitor transesterification,12 determine chain conformation distributions,13 study cyclic anhydride intermediates,14 investigate kinetics of (polyurethane) polymerization,15 determine the extent of O‐esterification,16 quantify the presence of ethyl esters during transesterification,17 study intermolecular interactions in oligomers,18 and elucidate mechanisms of polyesterification 19…”

Section: Introductionmentioning

confidence: 99%

Anti–müllerian hormone and ovarian reserve in systemic lupus erythematosus

Mok¹,

Chan²,

To³

2012

Arthritis & Rheumatism

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Objective.To study the level of anti-müllerian hormone (AMH) and its relationship to age and previous exposure to cyclophosphamide (CYC) in patients with systemic lupus erythematosus (SLE).Methods. Consecutive female patients ages 18-52 years who had menses at least once during the preceding 12 months and fulfilled >4 American College of Rheumatology criteria for SLE were recruited. AMH was determined using an enzyme-linked immunosorbent assay (ELISA) kit. Serum AMH levels were compared in patients with and without previous use of immunosuppressive agents. The relationship of the AMH level to the patient's age and CYC exposure was studied by linear regression and receiver operating characteristic (ROC) curve analysis.Results. A total of 216 patients were studied (mean ؎ SD age 35.1 ؎ 10.1 years, mean ؎ SD SLE duration 7.6 ؎ 5.9 years). The mean ؎ SD AMH level was significantly lower in patients previously exposed to CYC therapy than in those who had not been exposed after adjustment for age (1.58 ؎ 2.92 versus 1.73 ؎ 2.11 ng/ml; P ‫؍‬ 0.04). The median time interval between the AMH assay and the last dose of CYC administered was 6.7 years (interquartile range 3.4-8.5). AMH levels in users versus nonusers of other immunosuppressive agents, including mycophenolate mofetil, azathioprine, and the calcineurin inhibitors, were not statistically different. Linear regression revealed increasing age (beta ؊0.32, P ‫؍‬ 0.02) and each 5 gm of CYC exposure (beta ؊0.28, P ‫؍‬ 0.047) were independently associated with a lower AMH level. In patients ages 30 years and younger, a cumulative CYC dose cutoff of 5.9 gm yielded a sensitivity of 0.75 and a specificity of 0.80 for the prediction of undetectable AMH level on ROC curve analysis.Conclusion. AMH is a sensitive marker for ovarian damage due to previous CYC exposure in women with SLE.

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Section: Introductionmentioning

confidence: 99%

Anti–müllerian hormone and ovarian reserve in systemic lupus erythematosus

Mok¹,

Chan²,

To³

2012

Arthritis & Rheumatism

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“…Around this wavenumber region, it is associated with the vibrational modes of the ester block of COPE. The slight deviation of the COPE ester peak (from 1717 to 1720 cm −1 ) shows an increase in the amorphous form of COPE [ 40 ]. However, the shoulder at higher wavenumbers could be an indicator of the formation of a new ester chemical bond.…”

Section: Resultsmentioning

confidence: 99%

Enhancing the Interface Behavior on Polycarbonate/Elastomeric Blends: Morphological, Structural, and Thermal Characterization

et al. 2023

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A systematic study was performed to provide better understanding of the effect of elastomeric materials on the behavior of polycarbonate blends (PC). Thus, blends of PC with different amounts of elastomers, such as copolyether ester elastomer (COPE), acrylonitrile–butadiene–styrene (ABS), maleic anhydride-grafted ABS (ABS-g-MA), and styrene–ethylene–butylene–styrene (SEBS-g-MA) were prepared in a co-rotating twin-screw extruder. The materials were characterized by an electronic microscopy (SEM), an infrared spectroscopy (FTIR), and thermal (DSC) and thermo-mechanical (DMA) techniques. The incorporation of elastomeric phases was observed by changes in the FTIR band’s intensity, whereas a new shoulder of the ester band of COPE at 1728 cm−1 indicates the occurrence of a transesterification reaction. Unmodified and modified ABS (5% and 10%) did not affect the glass transition temperature (Tg) of PC, while 1% SEBS-g-MA slightly increased this value. PC/10% COPE showed that a decrease in Tg of 25 °C has a result of better compatibilization between both phases, which is visible via SEM. SEM analysis identified three main toughening mechanisms, depending on the type of elastomer. Unlike any other study, this work deepens the knowledge, in a comparative way, to understand the elastomeric effect at the interface and consequently, on the mechanical behavior of PC systems.

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“…Although both polymers show similar bands because of similar functionalities in their molecular structure, the C–O and the C=O stretching bands in the Raman spectrum are at specific locations, and thus allow for the identification of PBT and PC; the C=O stretching band of PBT is found at 1720 cm −1 , and for PC, the respective band is located at 1775 cm −1 . C–O stretching bands are found at 1280 cm −1 and 1235 cm −1 for PBT and PC, respectively [70]. In order to investigate the composition of the PBT–PC particles obtained after thermal rounding, Raman microscopy was employed (for instrumental details, see Section 2.3.3.).…”

Section: Resultsmentioning

confidence: 99%

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

Dechet

Bonilla

Lanzl³

et al. 2018

Polymers

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In this study, the feasibility of co-grinding and the subsequent thermal rounding to produce spherical polymer blend particles for selective laser sintering (SLS) is demonstrated for polybutylene terephthalate (PBT) and polycarbonate (PC). The polymers are jointly comminuted in a planetary ball mill, and the obtained product particles are rounded in a heated downer reactor. The size distribution of PBT–PC composite particles is characterized with laser diffraction particle sizing, while the shape and morphology are investigated via scanning electron microscopy (SEM). A thorough investigation and characterization of the polymer intermixing in single particles is achieved via staining techniques and Raman microscopy. Furthermore, polarized light microscopy on thin film cuts enables the visualization of polymer mixing inside the particles. Trans-esterification between PBT and PC during the process steps is investigated via vibrational spectroscopy and differential scanning calorimetry (DSC). In this way, a new process route for the production of novel polymer blend particle systems for SLS is developed and carefully analyzed.

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Poly(butylene terephthalate) polycarbonate transesterification: monitoring its progress with Fourier transform Raman spectroscopy

Cited by 9 publications

References 5 publications

Anti–müllerian hormone and ovarian reserve in systemic lupus erythematosus

Anti–müllerian hormone and ovarian reserve in systemic lupus erythematosus

Enhancing the Interface Behavior on Polycarbonate/Elastomeric Blends: Morphological, Structural, and Thermal Characterization

Spherical Polybutylene Terephthalate (PBT)—Polycarbonate (PC) Blend Particles by Mechanical Alloying and Thermal Rounding

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