Tensile properties epoxy nanocomposites

Bandyopadhyay et al. [138] have also studied the distribution of nanoclays such as NA and 30B in NR/ENR (containing 50 mol% epoxy) and NR/BR blends and their effect on the overall properties of the resultant nanocomposite blends. They calculated the preferential distribution of clays at various loadings in the blend compounds from the viscoelastic property studies from DMA. The tensile properties of the 50 50 NR/ENR and 50 50 NR/BR blend nanocomposites are shown in Table 5. It is apparent that in both the blends that the mechanical properties increase with increasing clay concentration up to a certain extent and then decrease. These results have been found to depend on matrix polarity and the viscosity of the blend compounds. 

Thermoset/CNT nanocomposites are processed [80, 81] in a similar way as PCN are prepared. Generally sonication is used to disperse CNT in the resin. Zhou and co-workers [82] incorporated 0-0.4 wt% of MWCNT in epoxy matrix by sonication technique and evaluated their mechanical properties. Improvement in property in all respects was observed up to 0.3 wt% of nanotube. Beyond this concentration the strength and elongation decrease though the modulus keeps increasing. As a result of addition of 0.3 wt% nanotube the tensile strength increases from 93.5 MPa to 121 MPa and % elongation increases from 4.0 wt% to 7.5 wt%. Schadler and coworkers [83] evaluated mechanical properties a MWCNT-epoxy nanocomposites... 

CdSe-CdS-ZnS core-multishell polymer nanocomposites were prepared by direct dispersion of CdSe-CdS-ZnS core-multishell QDs in an epoxy polymer matrix via a melt mixing technique. Nanocomposites filled with yellow-emitting QDs were more transparent than pure epoxy polymer. A shift in the luminescence of pure epoxy from the blue region to the yellow region was observed in the nanocomposite. Synthesized nanocomposites also showed enhanced tensile properties in comparison to pure epoxy polymer [236]. Several other studied reported the use of a melt blending process for the synthesis of semiconductor-polymer nanocomposites [237-241]. 

Concerning mechanical properties, the improvement in tensile properties provided by exfoliated smectites is superior to that of delaminated magadiite. The most significant improvement over corresponding epoxy-smectite nanocomposites is the optical transparency of the magadiite composites [143,183],... 

In this paper, we describe the mechanism for formation of epoxy-clay nanocomposites and compare the tensile properties of the intercalated and exfoliated forms of these nanocomposites. 

Ghorabi Shima, Rajabi Laleh, Siavash Madaeni Sayed, Zinadini Sims, and Ashraf Derakhshan Ali. Effects of three surfactant types of anionic, cationic and non-ionic on tensile properties and fracture surface morphology of epoxy/MWCNT nanocomposites. Iran. Polym. J. 21 no. 2 (2012) 121-130. 

FIGURE 9.21 Tensile properties (tensile strength, Young s modulus and strain at break) versus tiller content in a LDH epoxy nanocomposite. (From Ref. 70, copyright 2003, Elsevier, with permission.)... 

In terms of weight loss and heat release, nanocomposites are less effective than epoxy-APP, but on the other hand, APP reduces the thermal stability and hence the ignition time by 29%. Epoxy-LDHl and epoxy-LDH2 show ignition times comparable to that of neat resin. Furthermore, APP causes a depletion of mechanical properties of epoxy, whereas LDH-based epoxy nanocomposites show an increase in tensile strength. Young s modulus, and strain at break, and a reduction of thermal expansion and permeability... 

Bhuyan et al. (2010) synthesized organomodified clay/conjugated low saturated soybean oil/styrene nanocomposites with different clay contents from 1 to 5 wt%. The addition of 1 wt% organo-MMT clays induced superior wear behavior and better tribological properties. Zia et al. (2011) studied the impact of bentonite clays on mechanical properties and cytotoxicity of chitin-based polyurethane nanocomposites. The tensile strength of nanocomposites increased up to 300% with 4 wt% bentonite clay inclusions. Increasing the content of bentonite clays on nanocomposite products enabled the toxicity level of nanocomposites to increase. The optimal bentonite clay content was found to be 2 wt% when used as surgical threads due to the combination of better mechanical properties and lower toxicity level. Das et al. (2013) fabricated epoxy/polyuria-modified MMT nanocomposites... 

The tensile stress-strain curves of neat epoxy and epoxy nanocomposite systems with three different levels of exfoliation are shown in Fig. 2. The addition of 2.0 vol% of poorly exfoliated, i.e., mostly intercalated, a-ZrP nanoplatelets into the epoxy matrix improves the tensile modulus by a mere 8%, and reduces strength and elongation-at-break by 30% and 50%, respectively. These large drops in strength and elongation-at-break are possibly caused by the intercalated tactoids which may act as defects to deteriorate the properties of the epoxy matrix. 

Epoxy-modified Mesua ferrea L. seed oil-based polyurethane/clay nanocomposites at different loadings (1-5 wt%) have been studied as biocompatible biomaterials. The partially exfoliated nanocomposites were prepared by an ex situ solution technique under high mechanical shearing and adequate ultrasonication at room temperature. The nanocomposites exhibited enhanced mechanical properties such as tensile strength (twofold) and scratch hardness (five-fold), thermostability (to about 40°C), and an increase in the rate of biodegradation between five- and ten-fold. All the nanocomposites showed RBC haemolysis inhibition observed by anti-hemolytic assay carried out on the sterilised films. 

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