scholarly journals High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2237
Author(s):  
Eder H. C. Ferreira ◽  
Angela Aparecida Vieira ◽  
Lúcia Vieira ◽  
Guilhermino J. M. Fechine
Keyword(s):  
Graphene Oxide ◽  
High Viscosity ◽  
Tribological Performance ◽  
Multilayer Graphene ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Mechanical Reinforcement ◽  
Transmission Electron ◽  
Twin Screw ◽  
Mechanical Tensile

Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE-UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a significant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomography, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction coefficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.

scholarly journals Study of the Influence of the Almond Shell Variety on the Mechanical Properties of Starch-Based Polymer Biocomposites

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2049 ◽  
Author(s):  
Ana Ibáñez García ◽  
Asunción Martínez García ◽  
Santiago Ferrándiz Bou
Keyword(s):  
Charpy Impact ◽  
X Ray Diffraction ◽  
Almond Shell ◽  
Scanning Calorimetry ◽  
Commercial Mixture ◽  
Hardness Tests ◽  
Twin Screw ◽  
Ft Ir ◽  
Mechanical Tensile ◽  
The Individual

This article is focused on the development of a series of biodegradable and eco-friendly biocomposites based on starch polymer (Mater-Bi DI01A) filled with 30 wt% almond shell (AS) of different varieties (Desmayo Rojo, Largueta, Marcona, Mollar, and a commercial mixture of varieties) to study the influence of almond variety in the properties of injected biodegradable parts. The different AS varieties are analysed by means of Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD). The biocomposites are prepared in a twin-screw extruder and characterized in terms of their mechanical (tensile, flexural, Charpy impact, and hardness tests) and thermal properties (differential scanning calorimetry (DSC) and TGA). Despite observing differences in the chemical composition of the individual varieties with respect to the commercial mixture, the results obtained from the mechanical characterisation of the biocomposites do not present significant differences between the diverse varieties used. From these results, it was concluded that the most recommended option is to work with the commercial mixture of almond shell varieties, as it is easier and cheaper to acquire.

Study on Thermal Conductivity of Multilayer Graphene/NR Composite

2014 ◽  
Vol 933 ◽  
pp. 3-7 ◽  
Author(s):  
Gui Long Wu ◽  
Long Liu ◽  
Xiao Zong ◽  
Yan He ◽  
Ze Peng Wang
Keyword(s):  
Thermal Conductivity ◽  
Differential Scanning Calorimetry ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Mass Fraction ◽  
Structure Change ◽  
Multilayer Graphene ◽  
Scanning Calorimetry ◽  
Structure And Morphology ◽  
Transmission Electron

Graphene/NR composite was prepared in emulsion blending and the multilayer graphene was about 4-8 layers. Different mass fraction of this kind of graphene was mixed into NR in this work.The thermal conductivity of this compositive system was respected to be improved apparently since the high thermal conductivity of graphene. In this work, TEM(Transmission electron microscope) was used to observe the structure and morphology of the multilayer graphene. NETZSCH LFA was used to research the change of thermal conductivity with the fraction of grahene changing. DSC(differential scanning calorimetry) was used to research the structure change in the series of composites. The TEM results showed that the graphene we used is 4-5 layers. LFA had proved that the multilayer graphene has affected the thermal conductivity of matrix greatly and DSC also provided evidence to support the same views.

HYPERSTABILIZATION OF MARTENSITES

2012 ◽  
Vol 05 (01) ◽  
pp. 1250005 ◽  
Author(s):  
SERGEY KUSTOV ◽  
RUBEN SANTAMARTA ◽  
DANIEL SALAS ◽  
EDUARD CESARI ◽  
KONSTANTIN SAPOZHNIKOV ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Internal Friction ◽  
Parent Phase ◽  
Reverse Transformation ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Internal Friction Peak ◽  
Transmission Electron ◽  
Interphase Boundaries

The effect of hyperstabilization of martensite implies that the reverse martensitic transformation proceeds in two well separated stages. Namely, a small fraction of martensite (of the order of 10%) retransforms upon heating into the parent phase over a temperature range slightly higher than the nominal reverse transformation temperature, whereas the rest of the martensite retransforms through a re-nucleation of fine lamellae of the parent phase. The renucleation stage of the transformation is well defined and requires strong overheating of the order of 300 K with respect to the nominal transformation. In this letter, the results are discussed of a study of the hyperstabilization effect in different martensitic structures: faulted [Formula: see text] martensite in Cu–Al–Be system and twinned martensite in ferromagnetic Ni–Fe–Ga crystals by means of differential scanning calorimetry, transmission electron microscopy and internal friction. The conclusion has been drawn that hyperstabilization implies a severe blocking of the motion of interphase boundaries during the reverse transformation, which can be produced either due to a high concentration of highly mobile quenched-in defects ("sweeping" of defects during the reverse transformation) or due to a creation of obstacles by preliminary plastic deformation. The former mechanism requires very intense diffusion of quenched-in defects assisted by dislocations/interfaces, which has been confirmed by internal friction studies. It has been shown that the renucleation stage, which occurs at around 600 K for different alloys, is preceded by a relaxation internal friction peak. A possible role of this relaxation in renucleation of the parent phase is discussed.

scholarly journals PHBV/MWCNT Films: Hydrophobicity, Thermal and Mechanical Properties as a Function of MWCNT Concentration

2019 ◽  
Vol 3 (1) ◽  
pp. 12 ◽  
Author(s):  
Ana Paula Lemes ◽  
Thaís Larissa do Amaral Montanheiro ◽  
Ana Paula da Silva ◽  
Nelson Durán
Keyword(s):  
Electron Microscopy ◽  
Nucleating Agent ◽  
Wide Distribution ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Mwcnt Concentration ◽  
Multi Walled Carbon Nanotubes ◽  
Mechanical Tensile ◽  
Walled Carbon Nanotubes

The introduction of multi-walled carbon nanotubes (MWCNTs) into polymer matrixes has been an important tool to alter and improve some properties in polymer nanocomposites, including biodegradable polymers such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). In this work, PHBV nanocomposites with 0.05, 0.50, 1.00, 1.50 and 2.00 wt % of MWCNTs were produced by solvent casting. MWCNT morphology and structure were characterized by Raman spectroscopy, and transmission electron microscopy (TEM). It was observed that MWCNTs have a considerable amount of amorphous carbon (AC) onto their surface and a wide distribution of the tube diameter. MWCNTs act as the nucleating agent in the PHBV matrix, as verified by differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) showed that thermal stability was not significantly affected. The nanofiller dispersion into the PHBV matrix was not effective for concentrations from 1 wt % according to the micrographs obtained in scanning electron microscopy (SEM). The contact angle was changed with the introduction of MWCNTs, turning the nanocomposites hydrophobic and improving the mechanical tensile properties of the PHBV matrix.

scholarly journals Effect of Graphene Oxide as a Reinforcement in a Bio-Epoxy Composite

2021 ◽  
Vol 5 (3) ◽  
pp. 91
Author(s):  
Anthony Loeffen ◽  
Duncan E. Cree ◽  
Mina Sabzevari ◽  
Lee D. Wilson
Keyword(s):  
Graphene Oxide ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Scanning Calorimetry ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Materials Research ◽  
Improved Performance ◽  
Modified Hummers Method ◽  
Properties Of Composites

Graphene oxide (GO) has gained interest within the materials research community. The presence of functional groups on GO offers exceptional bonding capabilities and improved performance in lightweight polymer composites. A literature review on the tensile and flexural mechanical properties of synthetic epoxy/GO composites was conducted that showed differences from one study to another, which may be attributed to the oxidation level of the prepared GO. Herein, GO was synthesized from oxidation of graphite flakes using the modified Hummers method, while bio-epoxy/GO composites (0.1, 0.2, 0.3 and 0.6 wt.% GO) were prepared using a solution mixing route. The GO was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM) analysis. The thermal properties of composites were assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR results confirmed oxidation of graphite was successful. SEM showed differences in fractured surfaces, which implies that GO modified the bio-epoxy polymer to some extent. Addition of 0.3 wt.% GO filler was determined to be an optimum amount as it enhanced the tensile strength, tensile modulus, flexural strength and flexural modulus by 23, 35, 17 and 31%, respectively, compared to pure bio-epoxy. Improvements in strength were achieved with considerably lower loadings than traditional fillers. Compared to the bio-epoxy, the 0.6 wt.% GO composite had the highest thermal stability and a slightly higher (positive) glass transition temperature (Tg) was increased by 3.5 °C, relative to the pristine bio-epoxy (0 wt.% GO).

scholarly journals A new method in synthesis of polyurethane/graphite oxide nanocomposites by twin-screw extruder

2013 ◽  
Vol 16 (4) ◽  
pp. 45-53
Author(s):  
Van Thi Khanh Khuat ◽  
Tam Thanh Mai ◽  
Nhan Thuc Chi Ha ◽  
Huy Thuc Ha
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Graphene Oxide ◽  
Environmentally Friendly ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Time Saving ◽  
Transmission Electron ◽  
Twin Screw ◽  
Environmentally Friendly Method

In this study, we have synthesized polyurethane based on monoglyceride and 4.4 '-diphenyl methanediisocyanate (MDI) – an environmentally friendly polymer. Graphene oxite (GO) was used to reinforce for polyurethane forming polyurethane/graphene oxide (PU/GO) nanocomposite. The synthesis of PU and PU/GO was performed directly on the twinscrew extruder. This is a simple, time saving, economical and environmentally friendly method. Nanocomposites were manufactured with GO phase changed from 0.5% to 1.5% by weight. Structural analysis results of PU/GO showed a good dispersion through TEM figure (transmission electron microscopy). In addition, the mechanical and thermal properties of the nanocomposite were improved as compared to the original polyurethane. This study is a new step for the synthesis of polyurethane and nanocomposite based on polyurethane by the melt intercalation method.

scholarly journals Extruded PLA Nanocomposites Modified by Graphene Oxide and Ionic Liquid

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 655
Author(s):  
Cristian Sánchez-Rodríguez ◽  
María-Dolores Avilés ◽  
Ramón Pamies ◽  
Francisco-José Carrión-Vilches ◽  
José Sanes ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Graphene Oxide ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Twin Screw Extrusion ◽  
Scanning Calorimetry ◽  
Screw Extrusion ◽  
Ir And Raman Spectroscopies ◽  
Twin Screw ◽  
Ft Ir

Polylactic acid (PLA)-based nanocomposites were prepared by twin-screw extrusion. Graphene oxide (GO) and an ionic liquid (IL) were used as additives separately and simultaneously. The characterization of the samples was carried out by means of Fourier transform infrared (FT-IR) and Raman spectroscopies, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The viscoelastic behavior was determined using dynamic mechanical analysis (DMA) and rheological measurements. IL acted as internal lubricant increasing the mobility of PLA chains in the solid and rubbery states; however, the effect was less dominant when the composites were melted. When GO and IL were included, the viscosity of the nanocomposites at high temperatures presented a quasi-Newtonian behavior and, therefore, the processability of PLA was highly improved.

Effect of Silane Treated and Untreated Talc on the Properties of Thermoplastic Polyurethane/Polypropylene Blends

2013 ◽  
Vol 849 ◽  
pp. 121-126 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Filipan Veljko ◽  
Vesna Ocelić Bulatović
Keyword(s):  
Storage Modulus ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Twin Screw ◽  
Mechanical Tensile ◽  
Polypropylene Blends ◽  
Pp Blends

The effect of the silane treated talc on the mechanical and thermal properties of talc filled thermoplastic polyurethane/polypropylene blends (TPU/PP blends) was investigated. Thermoplastic polyurethane and polypropylene are partially miscible due to the lack of interfacial interaction between the nonpolar crystalline PP and polar TPU. Blends of TPU and PP with silane treated and untreated-talc were prepared using melt blending in a laboratory twin-screw extruder. Organosilane (3-glycidoxypropyl-trimetoxy silane coupling agent) was used to treat talc in order to improve the affinity between the filler and the TPU/PP blends. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and mechanical (tensile test) measurements were used to characterize the talc filled and silane treated talc filled composites and TPU/PP/talc blends. The addition of silane treated and untreated talc in TPU/PP blends improved miscibility in all investigated TPU/PP/talc blends. The silane treatment increases the storage modulus in all investigated TPU/PP/talc blends in comparison with that of the untreated TPU/PP/talc blends. The obtained DSC results show that the addition of silane treated talc increases the degree of crystallinity (χc) of TPU/PP/talc blends because of the improved adhesion between the polymer and the treated talc. Addition of silane treated talc improved the mechanical properties as compared to TPU/PP/talc blends without chemical modification of talc. The results of strength correlate to the values of the storage modulus and crystallinity of the investigated TPU/PP/talc blends.

Effect of Flow Fields on Morphology of PP/Nano/CaCO3 Composite and Its Rheological Behavior

Materials ◽  
2005 ◽  
Author(s):  
Han-Xiong Huang ◽  
Guo Jiang ◽  
Shan-Qiang Mao
Keyword(s):  
Crystallization Behavior ◽  
Filler Content ◽  
Melt Flow Index ◽  
Flow Fields ◽  
Flow Index ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Twin Screw

Polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was prepared using a co-rotating, intermeshing twin-screw extruder. The effect of flow fields on the morphology of the nanocomposite was investigated. Transmission electron microscopy (TEM) was used for the determination of the morphology in the nanocomposite. The crystallization behavior of the nanocomposite was studied by using differential scanning calorimetry (DSC) and the melt shear viscosity was investigated by a melt flow index tester. The study showed that the flow field, through appropriately combining the type of the screw elements in this work, plays an important role in developing morphology of the nanocomposite. In addition, it was shown that the melt viscosity for the nanocomposite at the filler content less than 10 wt% is lower than that of neat PP.

scholarly journals Investigation on the Effect of Hyperbranched Polyester Grafted Graphene Oxide on the Crystallization Behaviors of β-Nucleated Isotactic Polypropylene

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1988 ◽  
Author(s):  
Yansong Yu ◽  
Xi Jiang ◽  
Yiwei Fang ◽  
Jinyao Chen ◽  
Jian Kang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Isotactic Polypropylene ◽  
Photoelectron Spectroscopy ◽  
Crystallization Process ◽  
Hyperbranched Polyester ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystallization Behaviors ◽  
Transmission Electron

In this article, hyperbranched polyester grafted graphene oxide (GO) was successfully prepared. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were performed for its characterizations. On the other hand, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were also performed to study its influences on non-isothermal crystallization behaviors of β-nucleated isotactic polypropylene (β-iPP). The grafting ratios of hyperbranched polyester with different supermolecular structures were calculated to be 19.8–24.0 wt %, which increase with the degree of branching. The results showed that the grafting of hyperbranched polyester was advantageous in increasing the crystallization peak temperature Tp and decreasing the crystallization activation energy ΔE of β-iPP/GO composites, which contributed to the iPP’s crystallization process. Moreover, under all cooling rates (2, 5, 10, 20, 40 °C/min), crystallinities of β-iPP/GO were greatly improved after being grafted with hyperbranched polyester, because of the increase of the relative contents of α-phase αc and the average α-crystal sizes.

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