Polymer Engineering and Science

/Polymer Engineering and Science

Evaluation of the shape memory behavior of a poly(cyclooctene) based nanocomposite device

2018-03-12T14:44:46+00:00March 12th, 2018|Categories: Publications|

The objective of the present work is to investigate the electro-activated shape memory behavior of a polycyclooctene (PCO) based nanocomposite device. At this aim, carbon black (CB) and exfoliated graphite nanoplatelets (xGnP) were melt compounded with a PCO matrix crosslinked with a dicumylperoxide content of 2 wt% and a total filler amount of 4 wt%. Electrical resistivity measurements on bulk materials evidenced a noticeable decrease of the electrical resistivity upon CB addition, while no synergistic effects were detected mixing CB and xGnP. Nanocomposite with a CB amount of 4 wt% revealed also a noticeable heating capability through Joule effect for voltage levels higher than 100 V. The subsequent characterization of an electro active shape memory device based on this composition demonstrated how it is possible to prepare a shape memory nanocomposite material able to completely recover its original shape after 100 s with a voltage of 90 V. The retention of the shape memory behavior after several (50) programming cycles was also demonstrated. POLYM. ENG. SCI., 58:430–437, 2018. © 2017 Society of Plastics Engineers

Published in: "Polymer Engineering and Science".

Preparation and properties of phenolic resin/graphene oxide encapsulated SiO2 nanoparticles composites

2018-02-12T14:44:38+00:00February 12th, 2018|Categories: Publications|Tags: , |

The hybrids of graphene oxide (GO) encapsulated nano-SiO2 (SiO2-GO) were introduced into phenolic resin (PR) to enhance thermal stability of PR. The effect mechanism was investigated in detail. Through electrostatic self-assembly method, the SiO2 nanoparticles were evenly distributed onto the surface of GO. This structure could not only prevent the aggregation of nano-SiO2, but also alleviate the phenomenons of crimp and stack for GO sheets in PR. Nano-SiO2 and GO showed elaborate synergistic effect on thermal stability of PR. Compared with the pristine PR, the 2 wt% SiO2-GO/PR composite showed higher T5%, T10%, and Tdmax, which were increased by 65.39, 62.23, and 23.17°C, respectively. And the char yield at 800°C increased from 64.78% to 69.38%. Thus, SiO2-GO hybrids can facilitate the application of PR in the fields of heat insulation and ablation resistance. POLYM. ENG. SCI., 2018. © 2018 Society of Plastics Engineers

Published in: "Polymer Engineering and Science".

Influence of elongational flow generating nozzles on material properties of polypropylene nanocomposites

2018-01-05T14:44:59+00:00January 5th, 2018|Categories: Publications|

In this study, polymer nanocomposites (PNCs) based on polypropylene (PP), organoclay (used as nanoclay), and compatibilizer were prepared by a masterbatch (MB or two-step) as well as by a one-step process. These compounds were then injection molded into tensile test specimens and rectangular plates using conically and hyperbolically shaped nozzles. The use of these nozzles in the injection unit was to enhance intercalation and exfoliation in the PNCs by means of elongational flow. The pressure loss and temperature rise in the compound induced by this flow were characterized in temperature and pressure measurements. An additional calculation using a new analytic model showed good correlation with the measured values for the conically shaped nozzles whereas the pressure drops in the hyperbolically shaped nozzles were underpredicted. Mechanical as well as rheological characterizations were performed on the produced test specimens. The compounds from the MB process showed good intercalation and exfoliation and improved mechanical properties without any special elongational flow treatment. Similar properties were achieved with the one-step process and elongational treatment using a short hyperbolically or conically shaped nozzle. These results indicated that it was possible to eliminate one complete compounding step and achieve the same mechanical properties in polypropylene nanocomposites when elongational elements were used. POLYM. ENG. SCI., 58:3–12, 2018. © 2016 Society of Plastics Engineers

Published in: "Polymer Engineering and Science".

Effect of interfacial interaction on rheological, electrically conductive, and electromagnetic shielding properties of polyethylene/GO composites

2017-12-20T14:44:42+00:00December 20th, 2017|Categories: Publications|Tags: , |

To regulate interfacial interaction between the polyethylene (PE) and graphene oxide (GO), maleic anhydride grafted high density polyethylene (PE-g-MAH) was utilized to enhance interfacial interaction between PE matrix and GO particles. Moreover, as a comparative investigation, γ-aminopropyltriethoxysilane (KH550) was used to functionalize GO (f-GO) so as to improve the interfacial interaction between PE matrix and GO particles. Compared to the addition of the PE-g-MAH, the f-GO had better dispersion in the PE/f-GO composites, indicating that functionalization of the GO with KH550 was the most effective way to improve the dispersion of the GO. However, the gel point for the PE/GO composite was not observed because the fillers network was not formed in the PE/GO composite. Compared to the f-GO particles, addition of PE-g-MAH was efficiency to build network structure of the GO particles so that the electrical conductivity of the PE/GO composites can be effectively improved. Moreover, the electromagnetic interference shielding effectiveness (EMI SE) of the PE/GO composites with addition of PE-g-MAH (PE/M-GO) was consistently higher than that of the PE/f-GO composites, indicating that the PE-g-MAH can effectively improve the EMI SE of the PE/GO composites. In addition, the microwave absorption (SEA) was main shielding mechanism for the PE/f-GO, PE/M-GO, and PE/GO composites. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

Published in: "Polymer Engineering and Science".

Novel Pickering stabilizer constituted by graphene oxide and carbon nanotubes for Fabricating poly(methyl methacrylate) nanocomposites

2017-12-20T14:44:43+00:00December 20th, 2017|Categories: Publications|Tags: , |

A novel carbon nanohybrid Pickering stabilizer was synthesized via a hydrothermal reaction of 2-ethyl-4-methylimidazole (EMI), graphene oxide (GO), and carbon nanotubes (CNTs). The EMI/GO/CNTs encapsulated poly(methyl methacrylate) (PMMA) microspheres were achieved via suspension polymerization after the formation of stable oil-in-water (o/w) Pickering emulsion using the as-prepared EMI/GO/CNTs stabilizer, which were used to elaborate PMMA-based nanocomposites through compression molding technique. Infra-red (IR) spectra and contact angle (CA) measurements showed that EMI/GO/CNTs nanohybrids was amphiphilic in nature. Mechanical tests and scanning electron microscope observation were performed to characterize the properties and microstructure of the resulting nanocomposites. PMMA nanocomposites containing networking EMI/GO/CNTs nanohybrids exhibited the maximum flexural strength of 73.1 MPa and compressive strength of 218.4 MPa at a GO-to-CNTs mass ratio of 6:1, respectively. The influences of the amount of EMI/GO/CNTs stabilizer and the ratio of GO to CNTs on the structure and properties of PMMA nanocomposites were discussed. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

Published in: "Polymer Engineering and Science".

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