Preparation of cross-linked PVC-g-(St-MA) copolymer/organoclay nanocomposites and investigation of chemical characteristics, morphology, thermal, and mechanical properties

2019 ◽  
pp. 089270571988601
Author(s):  
Reza Izadpanah ◽  
Mostafa Rezaei ◽  
Saeid Talebi

The goal of this work is to investigate the effect of incorporating organoclays on the cross-link structure, morphology, and thermomechanical properties of cross-linked organoclay/polyvinyl chloride grafted with styrene and maleic anhydride (PVC- g-(St-MA)) copolymer nanocomposites (CPN). Cloisite30B (C30B) and Cloisite15A (C15A) organoclays were used for the preparation of cross-linked PVC- g-(St-MA) nanocomposites by the solution mixing route. The nanoclay content in nanocomposites varied from 0.2 wt% to 1 wt%. The chemical structure and interaction between PVC- g-(St-MA) cross-linked segments and nanoclays were studied by Fourier transform infrared (FTIR) peaks deconvolution method. FTIR spectroscopy suggested the lowest extent of hydrogen bonding interaction for C30B containing sample, which decreased with clay content increment. The morphology of nanocomposites was studied by X-ray diffraction and transmission electron microscopy methods. Morphological observation revealed a near to the exfoliation state for organoclays in PVC- g-(St-MA) nanocomposite containing 1 wt% C30B. However, C15A/PVC- g-(St-MA) nanocomposite (C15A-CPN) exhibited partially intercalated and agglomerated morphology. Differential scanning calorimetry examination was conducted to measure the glass transition temperature ( T g) of the segments. At the same clay content, the T g of the C30B containing nanocomposites were higher than that of C15A samples. The mechanical properties of these nanocomposites were also investigated. As a consequence, C30B-CPN showed improved mechanical properties compared to C15A-CPN and cross-linked PVC- g-(St-MA) samples.

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.


2014 ◽  
Vol 92 (7/8) ◽  
pp. 648-653
Author(s):  
C. Dohare ◽  
N. Mehta

The present work reports a detailed study of some physical properties of some novel glasses of Se98–xAg2Inx (x = 0, 2, 4, 6) system. Measurements of thermal transport properties (i.e., thermal conductivity, κ, and thermal diffusivity, χe) have been carried out using the transient plane source technique. Specific heat measurements have been done by differential scanning calorimetry. Thermomechanical properties (i.e., Vickers hardness, Hv, and modulus of elasticity, E) have been evaluated by the indenter test. The minimal energy for formation of microvoids, Eh, and microvoids volume, Vh, of the previously mentioned glassy system are discussed in terms of microhardness, Hv. Temperature and frequency dependence of dielectric constant, ε1, and dielectric loss, ε2, for the same system were measured in the frequency (50 Hz – 1000 kHz) and temperature (303–338 K) range. The experimental results illustrate that the values of dielectric constant, ε1, and dielectric loss, ε2, are decreased with frequency and increased with temperature. The maximum barrier height, Wb, is calculated using the dielectric measurements according to the Guintini equation. The morphology and microstructural analysis of as-prepared alloys are confirmed by X-ray diffraction, scanning electron microscope, and transmission electron microscope.


Author(s):  
Cleiton André Comelli ◽  
Richard Davies ◽  
HenkJan van der Pol ◽  
Oana Ghita

AbstractThe heating and extrusion process in fused filament fabrication (FFF) is significantly shorter than the conventional extrusion process where longer heating times and significant pressure are applied. For this reason, it is important to understand whether the crystal history of the feedstock is fully erased through the FFF process and whether the FFF process can be tailored further by engineering the crystallization of the feedstock filaments. In this context, a methodology for evaluating the influence of morphology and mechanical properties on different feedstock and extruded filaments is proposed. Filaments with three different PEEK 450G crystalline structures (standard crystallinity, drawn filament and amorphous filament) were selected and evaluated, before and after free extrusion. The resulting morphology, crystallinity and mechanical properties of the extruded filaments were compared against the feedstock properties. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential and fast scanning calorimetry (DSC/FDSC) and tensile test were the techniques used to evaluate the materials. The results showed clear differences in the properties of the feedstock materials, while the analysis of the extruded filaments points to a homogenization of the resulting material producing mostly similar mechanical properties. However, the use of the drawn filament highlighted a statistically significant improvement in crystallinity and mechanical performance, especially in strain values. This conclusion suggests the innovative possibility of improving the quality of manufactured parts by tailoring the microstructure of the feedstock material used in the FFF process. Graphical abstract


2006 ◽  
Vol 317-318 ◽  
pp. 669-672 ◽  
Author(s):  
D.H. Kim ◽  
Seong Soo Park ◽  
B.S. Jun ◽  
Jong Kook Lee ◽  
Kyu Hong Hwang ◽  
...  

Polymer/layered silicate nanocomposities were prepared by in situ polymerization with microwave process. The influence of the amount of clay on the structure and thermal properties for the synthesized nanocomposites were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). It was found that the structure of nanocomposites, an intercalated/exfoliated structure, depended on the clay content.


2003 ◽  
Vol 76 (2) ◽  
pp. 406-418 ◽  
Author(s):  
Rathanawan Magaraphan ◽  
Woothichai Thaijaroen ◽  
Ratree Lim-ochakun

Abstract Montmorillonite clay was organically modified by primary and quaternary ammonium salts (having C12-C18). The modified clay was added to a solution of natural rubber in toluene at various contents. Characterization of the structure of the nanocomposites was performed by using x-ray diffraction and transmission electron microscope. The results showed that the silicate layers of the clay were expanded so that the exfoliated nanocomposites were obtained at clay content below 10 phr; above that the nanocomposites became partially exfoliated. Moreover, long primary amine showed more improved mechanical properties than the quaternary one (at the same carbon numbers). The longer organic modifying agents resulted in better expansion of silicate layer distance indicating more intercalation of natural rubber molecules in between clay galleries. The curing properties were also improved. It was found that a small loading of 7 phr is enough to bring good mechanical properties in comparison to those of high structure silica filled and carbon black filled natural rubber vulcanizates.


2008 ◽  
Vol 23 (12) ◽  
pp. 3330-3338 ◽  
Author(s):  
Sonia Zulfiqar ◽  
Muhammad Ilyas Sarwar

Oligomerically modified reactive montmorillonite clay was used in the preparation of aramid-layered silicate nanocomposites. The dispersion behavior of organoclay was monitored in the aramid matrix synthesized from 4-aminophenylsulfone and isophthaloyl chloride in dimethylacetamide. These polyamide chains were end-capped with carbonyl chloride groups to interact chemically with oligomerically modified layered silicate. Thin composite films containing 2 to 20 wt% of organoclay were probed for x-ray diffraction (XRD), transmission electron microscopy (TEM), mechanical testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and water absorption measurements. XRD and TEM results described the distribution level of clay platelets and morphology of hybrid materials. Mechanical measurements revealed that modulus and strength improved up to 6 wt% clay loading, while toughness of nanocomposites increased with the addition of 2 wt% clay content in the matrix. The elongation showed a decreasing trend with increasing clay content in the hybrids. Thermal-decomposition temperatures of the nanocomposites were in the range 225 to 450 °C. The glass-transition temperature increased up to 12 wt% addition of organoclay in the matrix relative to pristine aramid depicting interfacial interactions among the phases. Water absorption of the nanocomposites reduced with augmenting organoclay loading, indicating decreased permeability.


Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 456
Author(s):  
Fahad A. Alharthi ◽  
Hamdah S. Alanazi ◽  
Amjad Abdullah Alsyahi ◽  
Naushad Ahmad

This study demonstrated the hydrothermal synthesis of bimetallic nickel-cobalt tungstate nanostructures, Ni-CoWO4 (NCW-NPs), and their phase structure, morphology, porosity, and optical properties were examined using X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), high resolution Transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) and Raman instruments. It was found that as-calcined NCW-NPs have a monoclinic phase with crystal size ~50–60 nm and is mesoporous. It possessed smooth, spherical, and cubic shape microstructures with defined fringe distance (~0.342 nm). The photocatalytic degradation of methylene blue (MB) and rose bengal (RB) dye in the presence of NCW-NPs was evaluated, and about 49.85% of MB in 150 min and 92.28% of RB in 90 min degraded under visible light. In addition, based on the scavenger’s study, the mechanism for photocatalytic reactions is proposed.


Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1851
Author(s):  
Hye-Seon Park ◽  
Chang-Kook Hong

Poly (l-lactic acid) (PLLA) is a promising biomedical polymer material with a wide range of applications. The diverse enantiomeric forms of PLLA provide great opportunities for thermal and mechanical enhancement through stereocomplex formation. The addition of poly (d-lactic acid) (PDLA) as a nucleation agent and the formation of stereocomplex crystallization (SC) have been proven to be an effective method to improve the crystallization and mechanical properties of the PLLA. In this study, PLLA was blended with different amounts of PDLA through a melt blending process and their properties were calculated. The effect of the PDLA on the crystallization behavior, thermal, and mechanical properties of PLLA were investigated systematically by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM), dynamic mechanical analysis (DMA), and tensile test. Based on our findings, SC formed easily when PDLA content was increased, and acts as nucleation sites. Both SC and homo crystals (HC) were observed in the PLLA/PDLA blends. As the content of PDLA increased, the degree of crystallization increased, and the mechanical strength also increased.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2367
Author(s):  
Junhyuk Son ◽  
Dong-Yurl Yu ◽  
Yun-Chan Kim ◽  
Shin-Il Kim ◽  
Min-Su Kim ◽  
...  

In this study, the interfacial reactions and mechanical properties of solder joints after multiple reflows were observed to evaluate the applicability of the developed materials for high-temperature soldering for automotive electronic components. The microstructural changes and mechanical properties of Sn-Cu solders regarding Al(Si) addition and the number of reflows were investigated to determine their reliability under high heat and strong vibrations. Using differential scanning calorimetry, the melting points were measured to be approximately 227, 230, and 231 °C for the SC07 solder, SC-0.01Al(Si), and SC-0.03Al(Si), respectively. The cross-sectional analysis results showed that the total intermetallic compounds (IMCs) of the SC-0.03Al(Si) solder grew the least after the as-reflow, as well as after 10 reflows. Electron probe microanalysis and transmission electron microscopy revealed that the Al-Cu and Cu-Al-Sn IMCs were present inside the solders, and their amounts increased with increasing Al(Si) content. In addition, the Cu6Sn5 IMCs inside the solder became more finely distributed with increasing Al(Si) content. The Sn-0.5Cu-0.03Al(Si) solder exhibited the highest shear strength at the beginning and after 10 reflows, and ductile fracturing was observed in all three solders. This study will facilitate the future application of lead-free solders, such as an Sn-Cu-Al(Si) solder, in automotive electrical components.


1998 ◽  
Vol 545 ◽  
Author(s):  
J. C. Caylor ◽  
A. M. Stacy ◽  
T. Sands ◽  
R. Gronsky

AbstractBulk skutterudite phases based on the CoAs3 structure have yielded compositions with a high thermoelectric figure-of-merit (“ZT”) through the use of doping and substitutional alloying. It is postulated that further enhancements in ZT may be attained in artificially structured skutterudites by engineering the microstructure to enhance carrier mobility while suppressing the phonon component of the thermal conductivity. In this work the growth and properties of singlephase CoSb3 and IrSb3 skutterudite thin films are reported. The films are synthesized by pulsed laser deposition (PLD) where the crystallinity can be controlled by the deposition temperature. Powder X-ray diffraction (PXRD), Transmission electron microscopy (TEM) and Rutherford- Back Scattering (RBS) were used to probe phase, structure, morphology and stoichiometry of the films as functions of growth parameters and substrate type. A substrate temperature of 250°C was found to be optimal for the deposition of the skutterudites from stoichiometric targets. Above this temperature the film is depleted of antimony due to its high vapor pressure eventually reaching a composition where the skutterudite structure is no longer stable. However, when films are grown from antimony-rich targets the substrate temperature can be increased to at least 350°C while maintaining the skutterudite phase. In addition, adhesion properties of the films are explored in terms of the growth mode and substrate interaction. Finally, preliminary room temperature electrical and thermal measurements are reported.


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