The effect of a sodium octacosanoate‐based nucleating agent on the crystallization of thermoplastic polyurethanes

Freitag, Christopher; Riegel, Izabel Cristina; Pezzin, Sérgio Henrique; Costa, Mirco; Amico, Sandro Campos

doi:10.1002/pen.21898

Cited by 5 publications

(4 citation statements)

References 22 publications

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“…Size exclusion chromatography traces reveal a substantial reduction of the number-and weight-average molecular weights from 110,000 to 20,000 and 229,000 to 66,000 Da, respectively (Figure S4), which suggests that the nucleation process is driven by chain scission and nucleation of the chain ends, as reported previously by others. 75,76 Indeed, a solution-cast mixture of the PU and 1%w/w dodecanoic acid displays the same thermal behavior as the neat PU ( Figure S5). We note that over the course of several months, Tc and Tm of the melt-processed PU/dodecanoic acid mixture increased to 20 °C and 52 °C, respectively, suggesting significant ageing.…”

Section: Resultsmentioning

confidence: 87%

Tailoring the Properties of a Shape-Memory Polyurethane via Nanocomposite Formation and Nucleation

et al. 2018

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Thermoplastic polyurethanes (PUs) can display shape-memory (SM) characteristics if their microphase-separated structure, consisting of domains formed by hard blocks and soft segments, respectively, is complemented with the ability of the soft segments to partially crystallize, so that the third phase thus formed can serve as the switching element for the shapememory effect. While property modifications of SMPUs usually require de novo synthesis, we show at the example of a commercially available poly(ester urethane) consisting of crystallizable poly(1,4-butylene adipate) soft/switching segments and hard segments composed of 4,4methylenediphenyl diisocyanate and 1,4-butanediol that the thermomechanical properties can also be modified by formulating nanocomposites and/or influencing the crystallization of the soft/switching segments via the addition of a nucleating agent. The incorporation of cellulose nanocrystals (CNCs) by simple melt-mixing allowed increasing the tensile storage modulus from 150 MPa (neat polymer) to 572 MPa (15% w/w CNCs) while the shape fixity at a specific fixing temperature was increased from 47 to 75%. The temperature at which good fixity (>97%) could be rapidly achieved was increased from 10 to 25ºC upon addition of 1% w/w dodecanoic acid, which served to nucleate the poly(1,4-butylene adipate) crystallization.

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Section: Resultsmentioning

confidence: 87%

Tailoring the Properties of a Shape-Memory Polyurethane via Nanocomposite Formation and Nucleation

et al. 2018

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“…Despite the wide potential application of TPUs, at least to the authors' knowledge, there are no previous reports where self-nucleation of TPUs and its effects on morphology and thermal properties have been explored in detail. One previous reference (ref 14) dealing with heterogeneous nucleation of TPUs reports that they have employed self-nucleation to calculate the nucleation efficiency of some nucleating agents; however, they do not provide any data about self-nucleation of the employed TPUs, and they do not quote the value of the ideal self-nucleation temperature needed for their efficiency calculations. In the present work, the influence of the macrodiol nature, as well as the influence of hard block content, on the self-nucleation behavior of different TPUs is studied.…”

Section: ■ Introductionmentioning

confidence: 99%

Tailoring the Morphology and Melting Points of Segmented Thermoplastic Polyurethanes by Self-Nucleation

et al. 2016

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It is demonstrated that the melting behavior and the morphology of three segmented thermoplastic polyurethane elastomers (TPUs) can be tailored by applying self-nucleation (SN) procedures. The self-nucleating temperature ranges for each of the TPU have been first determined by differential scanning calorimetry (DSC), while their morphology was studied by polarized light optical microscopy (PLOM), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). When the samples are cooled at slow to moderate rates after SN, the crystallization temperature of the TPUs increases by up to 45 °C, when the samples are ideally self-nucleated. This large reduction in supercooling increases the melting points of the samples by approximately 20 °C. At the same time, SAXS and AFM experiments demonstrate the growth of thicker lamellae under these slow to moderate cooling conditions as compared to untreated samples. When ideally self-nucleated samples are rapidly quenched (e.g., at rates of 100 °C min–1 or larger) from their self-nucleation temperature to room temperature, the effects of SN described above on the morphology and melting points of the samples disappear for the TPUs that do not crystallize fast enough.

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“…The enthalpy of fusion of PU and A‐PU fibers were found to be 2.292 J/g and 36.55 J/g, respectively. Crystals of ampicillin sodium salt form crystallization nuclei and nucleates PU .…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of ampicillin-incorporated electrospun polyurethane scaffolds for wound healing and infection control

Sabitha

Rajiv

2014

Polym Eng Sci

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Electrospinning is a desired method to produce interconnected flexible nanofibrous structures suitable for tissue engineering, drug delivery, and wound healing. Ampicillinloaded polyurethane (PU) nanofiber mats were electrospun with the antibiotic dispersed in well-oriented nanofibers. The identification of functional groups, molecular interactions and surface morphology of the fibers were analyzed using Infrared, Raman, 1 H NMR, SEM, and TEM. Weak interactions exist between the functional groups of ampicillin and PU in electrospun fibers at ratios 1:10, 1.5:10, and 2:10. The effect of b-lactam antibiotic ampicillin on the characteristics of electrospun PU was studied using XRD, TGA, and DSC. Their antibacterial property is proved by good zone of inhibition against Staphylococcus aureus and Klebsiella pneumonia. Cytotoxicity tests on the electrospun scaffolds were performed with normal human keratinocyte cells (HaCaT cells). Results indicate that ampicillin-incorporated PU scaffolds are well suited for applications in wound healing and infection control.POLYM. ENG. SCI., 00:000-000, 2014.

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The effect of a sodium octacosanoate‐based nucleating agent on the crystallization of thermoplastic polyurethanes

Cited by 5 publications

References 22 publications

Tailoring the Properties of a Shape-Memory Polyurethane via Nanocomposite Formation and Nucleation

Tailoring the Properties of a Shape-Memory Polyurethane via Nanocomposite Formation and Nucleation

Tailoring the Morphology and Melting Points of Segmented Thermoplastic Polyurethanes by Self-Nucleation

Preparation and characterization of ampicillin-incorporated electrospun polyurethane scaffolds for wound healing and infection control

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