High thermal insulation and compressive strength polypropylene foams fabricated by high-pressure foam injection molding and mold opening of nano-fibrillar composites

Zhao, Jinchuan; Zhao, Qingliang; Wang, Chongda; Guo, Bing; Park, Chul; Wang, Guilong

doi:10.1016/j.matdes.2017.05.093

Cited by 165 publications

(61 citation statements)

References 49 publications

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“…When the die temperature was 185 °C, the average cell diameter drops from 480.7 μm for PTFE0 to 63.1 μm for PTFE5, whereas the cell density increases from 3.3 × 10 4 to 8.6 × 10 7 cells/cm 3 . Zhao's work [38] also showed that by introducing PTFE fibrils, the cell sizes further decreased from 600 μm to 30 μm, with a dramatically increasing cell density by three orders of magnitude. The cell size distribution of all the foamed samples is shown in Figure S2 (from supplementary materials), the samples with PTFE nanofibrils show a much more uniform cell structure and narrower cell-size distribution.…”

Section: Extrusion Foaming Of Tpee/ptfe Nanocompositesmentioning

confidence: 95%

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Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Jiang

Liu

et al. 2019

Polymers

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In-situ fibrillated polytetrafluoroethylene (PTFE) enhanced nanocomposites were successfully prepared by mixing thermoplastic polyether ester elastomer (TPEE) and PTFE using a twin-screw extruder. Well-dispersed, long aspect ratio PTFE nanofibrils with a diameter of less than 200 nm were generated and interwoven into networks. Differential scanning calorimetry and in-situ polarized optical microscopy showed that the PTFE nanofibrils can greatly accelerate and promote crystallization of the TPEE matrix and the crystallization temperature can be increased by 6 • C. Both shearing and elongational rheometry results confirmed that the introduction of PTFE nanofibrils can significantly improve the rheological properties. The remarkable changes in the strain-hardening effect and the melt viscoelastic response, as well as the promoted crystallization, led to substantially improved foaming behavior in the continuous extrusion process using supercritical CO 2 as the blowing agent. The existing PTFE nanofibrils dramatically decreased the cell diameter and increased cell density, together with a higher expansion ratio and more uniform cell structure. The sample with 5% PTFE fibrils showed the best foaming ability, with an average diameter of 10.4-14.7 µm, an expansion ratio of 9.5-12.3 and a cell density of 6.6 × 10 7 -8.6 × 10 7 cells/cm 3 .2 of 16 has many excellent properties including thermal stability, good elasticity, chemical and oil resistance and, especially, rebound resilience at low-temperatures [3,5]. Also, TPEE has higher tear and impact strengths over a broad range of service temperatures when compared with other traditional TPEs [8]. Because of the extraordinary performance of TPEE, it has attracted increasing interest from many fields such as the sports, automotive and military industries.Although TPEE is an attractive engineering material, its application has to overcome the exorbitant price. To overcome this shortcoming, many attempts have been made to further improve the mechanical properties or to lower the weight (i.e., material consumption). Blending the matrix with micro-sized particles is an efficient method to improve the thermal or mechanical properties of TPEE [9][10][11][12][13]. Paszkiewicz et al. [12] added carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) to poly(trimethylene terephthalate) (PTT)-based TPEE to improve the electrical conductivity. They found that CNTs had greater potential to improve electrical conductivity when compared to GNPs due to the higher purity and higher aspect ratio. Qiu et al. [13] controlled the structure of mixed filler particles in TPEE to enhance the mechanical properties. The results showed that a closely packed particle structure can significantly improve the yield strength by about 40% with a decrease of about 20% in the Young's modulus, which is preferred in TPEE used as an elastomer.Foaming is a very effective way to lower the weight and expand the application of polymers. In recent decades, foamed materials have exhibited a balance between price and...

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Section: Extrusion Foaming Of Tpee/ptfe Nanocompositesmentioning

confidence: 95%

“…Many fibrils are entangled together to generate a reticular structure, which is believed to enhance the melt strength and prevent cells from rupture in the foaming process. Zhao's work shows that highly fibrillated PTFE could improve the foaming ability of PP in the injection-molding foaming process [30,38].…”

Section: Foam Characterizationmentioning

confidence: 99%

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Jiang

Liu

et al. 2019

Polymers

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“…ther analyze the effect of fillers on the thermal degradation of polymers, thermal degradation kinetics studies were performed to analyze the following rPP based composites: pure rPP, MCC/rPP, MCC/PP-g-MA/rPP, and T-ZnOw/MCC/PPg-MA/rPP composites. Flynn-Wall-Ozawa (OFW) equation (4) was used to analyze thermal degradation of composites. The activation energy (Ea) of composites was calculated from the temperature T corresponding to the different weight loss rate ( ) at different heating rates ( ).…”

Section: Thermal Degradation Kinetic Analysis In Order To Fur-mentioning

confidence: 99%

“…Polypropylene (PP) has been widely used for its high thermal stability, low density, low-cost, and recyclability [1][2][3][4]. However, PP suffers from insufficient rigidity at high temperatures and high brittleness at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Effect on Mechanical and Thermal Properties of Random Copolymer Polypropylene/Microcrystalline Cellulose Composites Using T-ZnOw as an Additive

Cheng

Zhang

Wang

et al. 2019

Advances in Polymer Technology

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Four-needle zinc oxide whisker (T-ZnOw) incorporated into microcrystalline cellulose/maleic anhydride grafted polypropylene/random copolymer polypropylene (MCC/PP-g-MA/rPP) composite was prepared by melt blending. 5 wt% PP-g-MA was used as a coupling agent to improve the interfacial compatibility between fillers and rPP. The effect of T-ZnOw on MCC/PP-g-MA/rPP composite was investigated by mechanical testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Addition of T-ZnOw enhanced the mechanical properties of composites with tensile and flexural strengths increasing by 10% and 6%, respectively. SEM studies showed an improvement in the compatibility of fracture surfaces, which was evident from the absence of gaps between fillers and rPP. Additionally, initial thermal decomposition temperature and maximum weight loss temperature of T-ZnOw/MCC/PP-g-MA/rPP composite were both higher than those of MCC/PP-g-MA/rPP composite. Thermal degradation kinetics suggested that T-ZnOw has a weak catalytic effect on MCC, resulting in the early degradation of MCC and adhesion to the surface of rPP. Because of the presence of inorganic whiskers, the remaining weight percent was more than that of other composites at the end of the reaction. Crystallization temperature of the T-ZnOw/MCC/PP-g-MA/rPP composite was almost 3~5°C higher than that of MCC/PP-g-MA/rPP composite and close to the crystallization temperature of pure rPP.

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“…However, owing to its low melt strength, melt elasticity, and high crystallinity, the fabrication of linear PP foams has not been successful [8][9][10][11][12]. Consequently, the resultant PP foam usually To improve the melt strength, considerable efforts have been made to optimize the PP foaming process, enhance PP foam ability as well as improve cellular structure [11,[13][14][15][16][17][18][19][20][21][22][23], such as long-chain branching [24,25], crosslinking [10,20,[26][27][28], polymer blending [11,29], and compounding [30,31]. In recent years, it was found nanoparticles such as graphene, carbon nanotubes, and carbon nanofibers added in PP could provide heterogeneous nucleation sites to increase cell density, minish cell size, improve cell uniformity, and at the same time reinforce the polymeric matrix [11,22,[32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Improving the Supercritical CO<sub>2</sub> Foaming of Polypropylene by the Addition of Fluoroelastomer as a Nucleation Agent

Yang¹,

Zhao²,

Xing³

et al. 2018

Preprint

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Polypropylene (PP) foam has a great deal of application since it normally exhibits non-uniform cell size distribution, low cell density, and cracked cells. In this study, a small amount of fluoroelastomer (FKM) was used as a nucleating agent to prepare well-defined microporous PP foam by supercritical CO2. It was observed that solid FKM was present as the nanoscale independent phase in PP matrix and the FKM could induce a mass of CO2 aggregation, which significantly enhanced the diffusion rate of CO2 in PP. The resultant PP/FKM foams exhibited much smaller cell size (～24 μm), and more than 16 times cell density (3.2×108 cells/cm3) as well as a much more uniform cell size distribution than that of the neat PP foam. PP/FKM foams possessed major concurrent enhancement in their tensile stress and compressive stress compared to neat PP foam. We believed that the added FKM played a key role in enhancing the heterogeneous nucleation, combined with the local strain field variation in the multiple-phase system, which was responsible for the considerably improved cell morphology of PP foaming. This paper provides a deep understanding of the scCO2 foaming behavior of PP in the presence of FKM.

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High thermal insulation and compressive strength polypropylene foams fabricated by high-pressure foam injection molding and mold opening of nano-fibrillar composites

Cited by 165 publications

References 49 publications

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Effect on Mechanical and Thermal Properties of Random Copolymer Polypropylene/Microcrystalline Cellulose Composites Using T-ZnOw as an Additive

Improving the Supercritical CO<sub>2</sub> Foaming of Polypropylene by the Addition of Fluoroelastomer as a Nucleation Agent

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