The effect of strain-hardening on the morphology and mechanical and dielectric properties of multi-layered PP foam/PP film

Lee, Sang-Jin; Zhu, Lei; Maia, João M.

doi:10.1016/j.polymer.2015.06.029

Cited by 30 publications

(27 citation statements)

References 34 publications

(64 reference statements)

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“…Owing to the weak melt strength of iPP, several approaches such as cross-linking, 34 branching, 28,32,35 blending, 23 and nanoparticle addition 22,24,33,36 have been investigated as ways to modify iPP to possess adequate melt strength and foaming processability. Cellulose nanober (CNF), 37 which is derived from abundant and renewable resources, has highly promising applications as a cell nucleating agent and a reinforcing agent for plastic foams.…”

Section: 27-30mentioning

confidence: 99%

Evolution of cellular morphologies and crystalline structures in high-expansion isotactic polypropylene/cellulose nanofiber nanocomposite foams

et al. 2018

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Herein, the development of cell morphology and crystalline microstructure of injection-molded isotactic polypropylene/cellulose nanofiber (PP/CNF) composite foams with 2-10-fold expansion ratios was investigated through scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). Compared with isotactic polypropylene (iPP) foams, the added CNF improved the cell morphology and resulted in a great reduction in cell size. Additionally, the PP lamella orientation and crystal type were notably altered during the core-back FIM process. As the expansion ratio increased, the original isotropic lamellae in the iPP foams were transformed into an oriented lamellar structure and then further transformed into a typical shish-kebab structure, while hybrid shishkebab structures were simultaneously generated in the high-expansion PP/CNF nanocomposite foams. Accordingly, the highest content of b-crystals was observed in the low-expansion iPP foams. In contrast, the b-crystal content in PP/CNF composites decreased monotonously as the expansion ratio increased, which resulted from the combined effects of CNF's nucleating ability for a-crystals and the more dominant extensional flow effect assisted by the added CNF.

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Section: 27-30mentioning

confidence: 99%

Evolution of cellular morphologies and crystalline structures in high-expansion isotactic polypropylene/cellulose nanofiber nanocomposite foams

et al. 2018

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“…[11][12][13][14][15][16][17] Chemical foaming agents and physical foaming agents are the most popular foaming agents for the preparation of PP microcellular foaming materials. 15,[18][19][20] Due to numerous advantages such as inexpensive, nontoxic, noncombustible, and ecofriendly, supercritical carbon dioxide (sc-CO 2 ) has become the most commonly used physical foaming agent for the preparation of PP foams with microsize cells. In addition, the uncontrollable foaming process and the uneven cell size greatly limit their application.…”

Section: Introductionmentioning

confidence: 99%

Strategy for the preparation of lightweight polypropylene/polyethylene‐octene elastomer composite foams with different phase morphologies using supercritical carbon dioxide

Wang

2019

J of Applied Polymer Sci

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Polypropylene (PP)/polyethylene-octene elastomer (POE) composites with a "sea-island" structure and a cocontinuous structure were prepared. With the selection of a suitable foaming temperature, the supercritical carbon dioxide foaming of PP/POE composites with different phase morphologies occurred only in the POE phase. The effects of the POE content, foaming temperature, pressure, and number of layers on the cell size, cell density, apparent density, foaming layer density, and foaming ratio under different phase morphologies were investigated by scanning electron microscopy, polarized optical microscopy, differential scanning calorimetry, and dynamic thermomechanical analysis. This article provides a novel approach for foaming PP at a low temperature. For PP/POE-blended composites with a "sea-island" structure, the foaming temperature is as low as 80 C, and for PP/POE alternating multilayered composites with a cocontinuous structure, foaming can occur at 40 C. Compared with the conventional methods for foaming PP, this method avoids the problems of a high foaming temperature, a narrow range of the foaming temperature, and a low melt strength of the PP. Thus, the PP foaming method was successfully improved, yielding a new technique for the preparation of lightweight PP.

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“…All the tests of the linear viscoelastic region of the PP materials were performed at stresses. Amplitude oscillatory shear tests were performed over a frequency range of 100-0.1 rad/s [30].…”

Section: Rheological Characterizationmentioning

confidence: 99%

Supercritical CO2 Foaming of Radiation Cross-Linked Isotactic Polypropylene in the Presence of TAIC

et al. 2016

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Abstract:Since the maximum foaming temperature window is only about 4 • C for supercritical CO 2 (scCO 2 ) foaming of pristine polypropylene, it is important to raise the melt strength of polypropylene in order to more easily achieve scCO 2 foaming. In this work, radiation cross-linked isotactic polypropylene, assisted by the addition of a polyfunctional monomer (triallylisocyanurate, TAIC), was employed in the scCO 2 foaming process in order to understand the benefits of radiation cross-linking. Due to significantly enhanced melt strength and the decreased degree of crystallinity caused by cross-linking, the scCO 2 foaming behavior of polypropylene was dramatically changed. The cell size distribution, cell diameter, cell density, volume expansion ratio, and foaming rate of radiation-cross-linked polypropylene under different foaming conditions were analyzed and compared. It was found that radiation cross-linking favors the foamability and formation of well-defined cell structures. The optimal absorbed dose with the addition of 2 wt % TAIC was 30 kGy. Additionally, the foaming temperature window was expanded to about 8 • C, making the handling of scCO 2 foaming of isotactic polypropylene much easier.

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The effect of strain-hardening on the morphology and mechanical and dielectric properties of multi-layered PP foam/PP film

Cited by 30 publications

References 34 publications

Evolution of cellular morphologies and crystalline structures in high-expansion isotactic polypropylene/cellulose nanofiber nanocomposite foams

Evolution of cellular morphologies and crystalline structures in high-expansion isotactic polypropylene/cellulose nanofiber nanocomposite foams

Strategy for the preparation of lightweight polypropylene/polyethylene‐octene elastomer composite foams with different phase morphologies using supercritical carbon dioxide

Supercritical CO2 Foaming of Radiation Cross-Linked Isotactic Polypropylene in the Presence of TAIC

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