Clay nanoplatelet induced morphological evolutions during polymeric foaming

Harikrishnan, G.; Patro, T. Umasankar; Unni, A. Raman; Khakhar, D. V.

doi:10.1039/c1sm05670k

Cited by 15 publications

(17 citation statements)

References 21 publications

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“…However, the mass density for the TPUCN10 nanocomposite foam increased compared with the TPUCN5 foam. It was found that the cell density of the TPUCN foam increased significantly as the clay content increased [39], which can also be visually observed in Fig. 8.…”

Section: Effect Of Nanoclay On the Morphology Of Nanocomposite Foamssupporting

confidence: 65%

The effect of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane nanocomposite foams

Wang

Jing

Peng

et al. 2015

Polymer Engineering & Sci

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The effects of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane (TPU)/clay nanocomposite (TPUCN) foams were investigated using differential scanning calorimetry, rheometry, scanning electron microscope, transmission electron microscopy, and X‐ray diffraction. It was found that the nanoclay acted as an effective nucleating agent for both crystal nucleation and cell nucleation. As a result, it significantly enhanced the crystallization behavior of the hard segment (HS) domains in TPU while refining the foamed structure of the microcellular injection molded parts. In particular, the average cell diameter of TPUCN foams decreased from 45 µm for neat TPU to 27 µm for TPUCN5 (5 wt% clay) and 18 µm for TPUCN10 (10 wt% clay). Furthermore, the cell density increased from 0.7 × 107 cell/cm3 for neat TPU to 1.4 × 107 cell/cm3 and 3.1 × 107 cell/cm3 for TPUCN5 and TPUCN10, respectively. In addition, the tensile strength also increased by 56.3% and 89.2% with 5 and 10 wt% clay content, respectively. By controlling the cell nucleation behavior through uniformly dispersed nanoclay, this study demonstrates that it is feasible to produce TPUCN foams via microcellular injection molding with desirable microcellular structures and improved mechanical properties. POLYM. ENG. SCI., 56:319–327, 2016. © 2015 Society of Plastics Engineers

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Section: Effect Of Nanoclay On the Morphology Of Nanocomposite Foamssupporting

confidence: 65%

The effect of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane nanocomposite foams

Wang

Jing

Peng

et al. 2015

Polymer Engineering & Sci

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“…The heterogeneities act as centers of favorable energetics, such that the supersaturation required for phase separation is considerably reduced. [7][8][9] During polymeric foaming, the presence of dispersed nanoscale heterogeneities in the continuous foaming medium might generate small bubbles leading to micro-/ nanocellular foams. These bubbles give rise to the microscopic morphology of the polymer foam, which in turn significantly affects the macroscopic properties.…”

Section: Introductionmentioning

confidence: 99%

Polymeric Foaming with Nanoscale Nucleants: A Surface Nanobubble Mechanism

et al. 2014

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The dimensionally restricted, diffusion-driven volumetric change of almost flat nucleated surface nanobubbles hosted on dispersed nanoscale surfaces is proposed as the probable mechanism of heterogeneous bubble generation during polymer-nanoscale-nucleant suspension foaming. By conducting numerical simulations, this hypothesis is used to predict the final bubble sizes upon polymeric foaming with nanoscale nucleants and to compare them with reported experimentally determined values. The volumetric change in the bubble hosted on the miniscule surface is envisaged to occur due to two parallel diffusion processes: 1) through the contact line of the bubble cap with the surface, and 2) through the curved gas-polymer interface. The foaming conditions determine the direction and molar rate of both these diffusions. The mechanism explains the relative nucleating efficiency of nanoscale surfaces experimentally observed during reactive and nonreactive polymeric foaming by predicting the growth or dissolution of the bubble. In the case of nonreactive thermoplastic foaming, the size of the bubbles released to the bulk from the nanoscale surface varies in a near linear fashion with respect to the size of the nucleants, limited to a maximum nucleant size. Beyond this maximum, the size of bubble generated is independent of the nucleant size. However, increase in the initial nanoscopic contact angle does not significantly affect the bubble size upon detachment from the surface.

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“…[279] Furthermore, it should be considered that in reactive foams two phases govern the foaming dynamics and hence the morphological development: the continuously polymerising liquid matrix and the disperse gas phase. [280] Both phases are strongly influenced by several parameters (e.g. rate of gas production, diffusivity) being surface tension, temperature and viscosity important on the bubble growth, formation and stability.…”

Section: Morphological Analysismentioning

confidence: 99%

“…Hence, if temperature increases, both viscosity and surface tension decrease, and then membranes become thinner and in some cases rupture because they cannot support the polymer stresses. [11,121,279,280] Besides these parameters, in polymer nanocomposite foams, two other competing effects influence the cell diameter and should be taken into account: the blowing effect, which increases the cell diameter and the nucleation effect which decreases the cell diameter. The blowing effect is produced by the presence of water on the surface of the nanoparticles.…”

Section: Morphological Analysismentioning

confidence: 99%

Estudio de Nanocompuestos de Espumas de Poliuretano Reforzadas con Nanocargas en Base Carbono

Bernal¹,

Mar²

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A la meua familia AGRADECIMIENTOSQuisiera agradecer, en primer lugar, al Ministerio de Ciencia e Investigación por la financiación para la realización de esta Tesis, mediante la concesión de la Beca FPI.A mis directores de Tesis, Dra. Raquel Verdejo y Dr. Miguel Ángel López Manchado por darme la oportunidad de trabajar con vosotros. A Raquel, por todo lo que me has enseñado durante estos años y por todo el tiempo que me has dedicado. A Miguel Ángel por tus comentarios constructivos, tus consejos y tu paciencia.A mi tutor en la UPV, Prof. Vicente Amigò por toda la ayuda que me has brindado sin apenas conocerme.Al Prof. Miguel Ángel Rodríguez Pérez de la Universidad de Valladolid por darme la posibilidad de trabajar en tu grupo y aprender más sobre espumas.I would like to thank Prof. Anthony J. Ryan, from The University of Sheffield, and Prof. Isabelle Huynen, from Université Catholique de Louvain, for your support and interest on my work.A todos mis compañeros del grupo por todos los ánimos y las risas. A Mario, Lean, Laura Peponi, Nicoletta, Iván y Sami. A mis chicas, Nella, Nat y Lauris, por todos los buenos momentos juntas entre recetas de cocina, clases de punto y bailes Bollywood! Quiero agradecer especialmente a Nella por ser mi profesora de la vida durante estos años y por las largas tardes-noches compartidas en la oficina. Y a Mario, nuestro "chico guapo" por todo el apoyo y por esas "características limitantes" que nos unen.A todo el grupo de Cauchos, en especial a Juan, Irene, Marta y Pilar, por ser como sois y por todas esas celebraciones en el laboratorio con vino, callos, migas y pasteles. Y a Miguel Arroyo, por esas paellas "madrileñas" que me hacen sentir como en casa.A Rodri, Jose e Isabel Quijada por haberme dejado participar en vuestros trabajos, por todo lo que he aprendido con vosotros y por haber confiado en mí.Al grupo del CellMat de la Universidad de Valladolid por haberme acogido tan bien durante las semanas que he estado con vosotros. En especial a Samu, Sergio y a Eusebio por vuestra colaboración en mis experimentos de radioscopia y DMA.I would like to thank my dear friends Masa, AC and Susi, for our great times in Sheffield.A special thanks to Isabel and Margherita for taking care of me during those hard months in Louvain-la-Neuve and for your friendship. Grazie Margheri per le nostre pause caffè e tutti gli scherzi! A todos mis amigos que me habéis apoyado durante este tiempo y, aunque en "la terreta" siempre os he tenido cerca. Y gracias a todas las personas que me han ayudado durante estos años. RESUMENLas espumas de nanocompuestos poliméricos tienen un gran interés tanto en áreas tecnológicas como científicas. Esto es debido a la combinación de las excelentes propiedades de las nanopartículas y la tecnología de espumado, dando lugar al desarrollo de materiales ligeros y multifuncionales. Este tipo de sistemas se utilizan en aplicaciones de alto rendimiento tan diversas como biomedicina, electrónica, paneles estructurales y embalajes, entre otras.Esta Tesis está basada en el desarro...

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Clay nanoplatelet induced morphological evolutions during polymeric foaming

Cited by 15 publications

References 21 publications

The effect of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane nanocomposite foams

The effect of nanoclay on the crystallization behavior, microcellular structure, and mechanical properties of thermoplastic polyurethane nanocomposite foams

Polymeric Foaming with Nanoscale Nucleants: A Surface Nanobubble Mechanism

Estudio de Nanocompuestos de Espumas de Poliuretano Reforzadas con Nanocargas en Base Carbono

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