scholarly journals Physical Hybrid of Nanographene/Carbon Nanotubes as Reinforcing Agents of NR-Based Rubber Foam

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2346
Author(s):  
Sahar Shojaie ◽  
Ali Vahidifar ◽  
Ghasem Naderi ◽  
Elham Shokri ◽  
Tizazu H. Mekonnen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cell Size ◽  
Rubber Matrix ◽  
Mechanical And Thermal Properties ◽  
Molding Process ◽  
Cell Size Distribution ◽  
Curing Behavior ◽  
Degradation Temperature ◽  
Nanocomposite Foams ◽  
Hybrid Fillers

Natural rubber (NR) foams reinforced by a physical hybrid of nanographene/carbon nanotubes were fabricated using a two-roll mill and compression molding process. The effects of nanographene (GNS) and carbon nanotubes (CNT) were investigated on the curing behavior, foam morphology, and mechanical and thermal properties of the NR nanocomposite foams. Microscope investigations showed that the GNS/CNT hybrid fillers acted as nucleation agents and increased the cell density and decreased the cell size and wall thickness. Simultaneously, the cell size distribution became narrower, containing more uniform multiple closed-cell pores. The rheometric results showed that the GNS/CNT hybrids accelerated the curing process and decreased the scorch time from 6.81 to 5.08 min and the curing time from 14.3 to 11.12 min. Other results showed that the GNS/CNT hybrid improved the foam’s curing behavior. The degradation temperature of the nanocomposites at 5 wt.% and 50 wt.% weight loss increased from 407 °C to 414 °C and from 339 °C to 346 °C, respectively, and the residual ash increased from 5.7 wt.% to 12.23 wt.% with increasing hybrid nanofiller content. As the amount of the GNS/CNT hybrids increased in the rubber matrix, the modulus also increased, and the Tg increased slightly from −45.77 °C to −38.69 °C. The mechanical properties of the NR nanocomposite foams, including the hardness, resilience, and compression, were also improved by incorporating GNS/CNT hybrid fillers. Overall, the incorporation of the nano hybrid fillers elevated the desirable properties of the rubber foam.

Effect of Nanoclay on the Physical-Mechanical and Thermal Properties and Microstructure of Extruded Noncross-Linked LDPE Nanocomposite Foams

2011 ◽  
Vol 471-472 ◽  
pp. 751-756 ◽  
Author(s):  
F. Zandi ◽  
M. Rezaei ◽  
A. Kasiri
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Cell Size ◽  
Flame Retardancy ◽  
Image Analyzer ◽  
Mechanical And Thermal Properties ◽  
Average Cell Size ◽  
Cell Size Distribution ◽  
Average Cell ◽  
Nanocomposite Foams

Novel noncross-linked low density polyethylene (LDPE) foams were produced by extrusion process. In this study the effects of Organophilic Montmorillonite (OMMT) nanoclay (DK1) on thermal conductivity, flame retardancy, morphological and mechanical properties of LDPE foams have been investigated. Nanoclay dispersion in LDPE foam structure was examined by X-ray diffraction (XRD), microstructure was observed by an optical microscope and analyzed by Bel View image analyzer, thermal conductivity was studied by a simple transient method, mechanical properties was investigated using a tensile-compression Zwick-Roell machine as well as the flame retardancy of the samples was examined by flammability test. The optimum nanoclay content was determined by comparison of the properties in nanocomposite and neat LDPE foams. Due to the presence of nanoclay in the foam and decreasing the cell nucleation energy around the nanoclay, the average cell size was decreased as well as the cell density and microstructure uniformity was increased. In XRD patterns of LDPE nanocomposite foams, OMMT (DK1) characteristic peak was not observed as evidence of nanoclay intercalation-exfoliation in the polymer matrix, which led to the production of foams with homogenous microstructure. Furthermore, this nanocomposites showed lower thermal conductivity compared to neat LDPE foam, which can be attributed to the cell size reduction as well as narrow cell size distribution in nanocomposite foams. Compression test results demonstrated that LDPE nanocomposite foams with proper clay contents have improved mechanical properties (Young’s modulus, compressive strength). Furthermore due to the presence of DK1 nanoclay, LDPE foam showed a good char formation as an evidence of their flame retardancy.

Effect of Nanoclay on the Mechanical and Thermal Properties of Rigid Polyurethane/Organoclay Nanocomposite Foams Blown with Cyclo and Normal Pentane Mixture

2011 ◽  
Vol 471-472 ◽  
pp. 584-589 ◽  
Author(s):  
M. Valizadeh ◽  
M. Rezaei ◽  
A. Eyvazzadeh
Keyword(s):  
Thermal Conductivity ◽  
Size Distribution ◽  
Cell Size ◽  
Polyurethane Foam ◽  
Mechanical And Thermal Properties ◽  
Cell Size Distribution ◽  
Nanocomposite Foams ◽  
Cloisite 30B ◽  
K Factor ◽  
Pu Foams

Polyurethane (PU)/Clay nanocomposite rigid foams were synthesized with modified layered silicate clay (organoclays, Cloisite 30B). PU foams were prepared by a batch reaction injection molding process. Organoclay was dispersed first in the isocyanate component using an ultrasonic homogenizer and then mixed with polyol and physical blowing agent mixture to produce nanocomposite PU foams. To study the reaction possibility between cloisite 30B and isocyanate as well as the effect of sonication on the reaction, Fourier transfer infrared (FTIR) analysis was conducted. The dispersion of organoclay in the rigid PU/clay nanocomposite foams was analyzed by wide angle X-ray diffraction (XRD). The microstructure of the foams was studied by an optical microscope and image analysis software. It was concluded that with increasing of nanoclay content the cell size is decreased and the cell size distribution is narrowed. The mechanical properties of pure and nanocomposite foams were examined by compression test. The data obtained from the compressive stress-strain curves reveals that the strength and modulus of polyurethane foam increase by addition of organoclay up to 1wt% and then decrease. Thermal conductivity coefficient (k-factor) of rigid PU nanocomposite and neat foams was measured by a simple transient method. The thermal conductivity results demonstrated that the polyurethane foam k-factor continuously decrease by addition of organoclay. It can be attributed to the reduced cell size as well as narrow cell size distribution in of nanocomposite foams.

Synthesis and Characterization of Montmorillonite-Carbon Nanotubes Hybrid Fillers for Nanocomposites

2012 ◽  
Vol 20 (8) ◽  
pp. 693-700
Author(s):  
Liliana Madaleno ◽  
Ryszard Pyrz ◽  
Lars R. Jensen ◽  
José J. C. Pinto ◽  
Augusto B. Lopes ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapour ◽  
Interlayer Spacing ◽  
X Ray Diffraction ◽  
Nanocomposite Foams ◽  
Montmorillonite Clays ◽  
Hybrid Fillers ◽  
Clay Layers

Montmorillonite-carbon nanotubes hybrids were prepared by growth of carbon nanotubes (CNT) on five different types of iron-montmorillonite clays using the chemical vapour deposition (CVD) method. Microscopy studies revealed the presence of carbon nanotubes protruding from clay surfaces and linking the clay layers in a network structure. X-ray diffraction results showed changes in the clay interlayer spacing induced by growth of carbon nanotubes within the layers of iron-montmorillonites. The quality of the resulting carbon nanotubes was evaluated by Raman spectroscopy and thermogravimetric analyzes were used to evaluate the amount of carbon nanotubes and its thermal stability. The method used for the preparation of the iron-montmorillonites appeared to be critical for the quality and quantity of carbon nanotubes obtained in each hybrid. In a preliminary study the hybrids were used to reinforce polyurethane nanocomposite foams.

Polyolefinic nanocomposite foams: Review of microstructure-property relationships, applications, and processing considerations

2020 ◽  
pp. 0021955X2097975
Author(s):  
Anish Kumar ◽  
Bhaskar Patham ◽  
Smita Mohanty ◽  
Sanjay Kumar Nayak
Keyword(s):  
Mechanical Properties ◽  
Cell Size ◽  
Cell Size Distribution ◽  
Nano Scale ◽  
Nanocomposite Foams ◽  
Nucleation Sites ◽  
The Matrix ◽  
Light Weighting ◽  
Processing Techniques ◽  
Processing Aids

In this review, we survey the state of the art on polymeric foams incorporating nano-scale fillers. Particular focus of the review is on foams from polyolefinic nanocomposite formulations incorporating a wide variety of fillers. The nano-scale additives can influence the foam structure and properties in two ways: Firstly, they can act as composite reinforcement to enhance the mechanical properties and functionality of the matrix polymer; and secondly, they can act as foaming-processing aids through modification of the rheological, thermal and crystallization properties of the matrix as well as serving as heterogeneous nucleation sites. Through a combination of these influences, and using advanced processing techniques it is possible to achieve nanocomposite foams that have higher cell density, and more uniform cell size or controlled cell-size distribution. Such controlled foam morphologies, in turn, can yield better specific mechanical properties resulting in more effective light-weighting solutions. Further, the nano-scale additives can impart additional desired functionality resulting in multi-functional foams. In this article, we provide an overview of the mechanical, thermal and a few other relevant functional properties – such as piezoelectric sensitivity, acoustics, and filtration efficiency – of foams prepared using nanocomposite formulations, along with the processing considerations for achieving high quality foams using such materials.

Physico-mechanical properties and cell microstructure of cross-linked PVC/organoclay nanocomposite foams prepared at various processing conditions

2020 ◽  
pp. 089270572097869
Author(s):  
Pezhman Rezaei ◽  
Mostafa Rezaei ◽  
Saeid Talebi ◽  
Amin Babaie
Keyword(s):  
Mechanical Properties ◽  
Size Distribution ◽  
Cell Size ◽  
Cell Density ◽  
Expansion Ratio ◽  
Molding Pressure ◽  
Cell Size Distribution ◽  
Gel Content ◽  
Nanocomposite Foams ◽  
Cloisite 30B

Cross-linked polyvinyl chloride (C-PVC) foams and their nanocomposite foams, containing Cloisite 30B nanoclays were prepared. The effects of compression molding pressure and time on the morphology and mechanical properties of different foams were studied. Increment of molding pressure led to higher apparent density, gel content, cell density, and expansion ratio, and wider cell size distribution, which improved the mechanical properties of the foams. Additionally, with the increasing of molding time, lower cell density and final expansion ratio, narrower cell size distribution, and higher gel content and mechanical properties could be obtained. Moreover, incorporation of Cloisite 30B nanoclay in a PVC matrix not only improved cellular microstructure and mechanical properties but also reduced water uptake ratios of nanocomposite foams.

1465 - Cell size distribution of planktonic bacteria in shallow lakes

2018 ◽  
Author(s):  
Zsuzsanna Márton ◽  
Bianka Csitári ◽  
Tamas Felfoldi ◽  
Anna J Szekely ◽  
Attila Szabo
Keyword(s):  
Size Distribution ◽  
Cell Size ◽  
Shallow Lakes ◽  
Cell Size Distribution ◽  
Planktonic Bacteria

scholarly journals Effect of Organo-Modified Montmorillonite Nanoclay on Mechanical, Thermo-Mechanical, and Thermal Properties of Carbon Fiber-Reinforced Phenolic Composites

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 754
Author(s):  
Jantrawan Pumchusak ◽  
Nonthawat Thajina ◽  
Watcharakorn Keawsujai ◽  
Pattarakamon Chaiwan
Keyword(s):  
Thermal Properties ◽  
Carbon Fiber ◽  
Bending Strength ◽  
Mechanical And Thermal Properties ◽  
Fiber Reinforced ◽  
Heat Resistant ◽  
Degradation Temperature ◽  
Modified Montmorillonite ◽  
Carbon Fiber Reinforced ◽  
Montmorillonite Nanoclay

This work aims to explore the effect of organo-modified montmorillonite nanoclay (O-MMT) on the mechanical, thermo-mechanical, and thermal properties of carbon fiber-reinforced phenolic composites (CFRP). CFRP at variable O-MMT contents (from 0 to 2.5 wt%) were prepared. The addition of 1.5 wt% O-MMT was found to give the heat resistant polymer composite optimum properties. Compared to the CFRP, the CFRP with 1.5 wt% O-MMT provided a higher tensile strength of 64 MPa (+20%), higher impact strength of 49 kJ/m2 (+51%), but a little lower bending strength of 162 MPa (−1%). The composite showed a 64% higher storage modulus at 30 °C of 6.4 GPa. It also could reserve its high modulus up to 145 °C. Moreover, it had a higher heat deflection temperature of 152 °C (+1%) and a higher thermal degradation temperature of 630 °C. This composite could maintain its mechanical properties at high temperature and was a good candidate for heat resistant material.

Effects of Particles Size of Nanosilica on Properties of Polybenzoxazine Nanocomposites

2015 ◽  
Vol 659 ◽  
pp. 394-398 ◽  
Author(s):  
Nutthaphon Liawthanyarat ◽  
Sarawut Rimdusit
Keyword(s):  
Particle Size ◽  
Silica Nanoparticles ◽  
Primary Particle ◽  
Mechanical And Thermal Properties ◽  
Particle Sizes ◽  
Barrier Effect ◽  
Degradation Temperature ◽  
Maximum Value ◽  
Wetting Behaviors ◽  
Composite Samples

Polybenzoxazine nanocomposites filled with three different sizes of silica nanoparticles are investigated for their mechanical and thermal properties. In this research, silica nanoparticles with primary particle sizes of 7, 14 and 40 nm were incorporated in polybenzoxazine matrix at a fixed content of 3% by weight. From the experimental results, the storage modulus of the polybenzoxazine nanocomposite was found to systematically increase with decreasing the particle sizes of nanosilica suggesting better reinforcement of the smaller particles. Glass transition temperature was found to slightly increase with the addition of the silica nanoparticles. The uniformity of the composite samples were also evaluated by thermogravimetric analysis to show good dispersion of the silica nanoparticles in the composite samples as a result of high processability of the benzoxazine resin used i.e. low A-stage viscosity with good wetting behaviors. Degradation temperature at 5% weight loss (Td,5) of polybenzoxazine nanocomposites filled with different particle sizes of silica nanoparticles was found to increase from the value of 325 °C of the neat polybenzoxazine to the maximum value of about 340 °C with an addition of the nanosilica of the smallest particle size used. Finally, the smaller nanosilica particle size was also found to show more pronounced effect on Td,5enhancement of the composite samples as a result of greater barrier effect from larger surface area of the smaller particles.

Fatigue of a Nanocomposite Laminate

2008 ◽  
Author(s):  
Justin W. Wilkerson ◽  
Jiang Zhu ◽  
Daniel C. Davis
Keyword(s):  
Carbon Nanotubes ◽  
Polymer Nanocomposite ◽  
Weight Percent ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Carbon Fabric ◽  
Molding Process ◽  
Functionalized Carbon Nanotubes ◽  
Multi Scale ◽  
Reinforced Polymer

A multi-scale carbon fiber reinforced polymer nanocomposite laminate, with strategically incorporated fluorine functionalized carbon nanotubes at 0.2 weight percent, is studied for improvements in strength, stiffness and fatigue life under both tension-tension fatigue (R = +0.1) and tension-compression fatigue (R = −0.1) loading. The nanotubes were incorporated into the carbon fabric, and laminates were fabricated using a high temperature vacuum assisted resin transfer molding process. The influence of the fluorinated functionalized carbon nanotubes on the evolution of damage and the resistance to catastrophic failure is credited for these mechanical property improvements.

scholarly journals Experimental-numerical studies of the effect of cell structure on the mechanical properties of polypropylene foams

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 713-723
Author(s):  
Wei Gong ◽  
Tuan-Hui Jiang ◽  
Xiang-Bu Zeng ◽  
Li He ◽  
Chun Zhang
Keyword(s):  
Mechanical Properties ◽  
Size Distribution ◽  
Cell Size ◽  
Cell Structure ◽  
Structure Parameters ◽  
Cell Size Distribution ◽  
Numerical Studies ◽  
Polypropylene Foam ◽  
The Impact ◽  
The Relationship

AbstractThe effects of the cell size and distribution on the mechanical properties of polypropylene foam were simulated and analyzed by finite element modeling with ANSYS and supporting experiments. The results show that the reduced cell size and narrow size distribution have beneficial influences on both the tensile and impact strengths. Decreasing the cell size or narrowing the cell size distribution was more effective for increasing the impact strength than the tensile strength in the same case. The relationship between the mechanical properties and cell structure parameters has a good correlation with the theoretical model.

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