The extreme stretching of dielectric elastomers in sensors, actuators, and energy harvesting devices is a common phenomenon where the materials are prone to fracture under the influence of flaws and notches. In this work, we have investigated the length of flaw sensitivities of two widely used dielectric materials, acrylic (VHB) and silicone (Ecoflex) elastomers under a pure shear loading and established that the length of flaw sensitivity of acrylic is almost double than that of silicone. Therefore, the acrylic elastomer is safer to operate for small notches as compared to the silicone material. However, within the flaw sensitive length, failure stretch, fracture toughness and failure stress are more for Ecoflex than those for VHB. It is found that the failure stretch and the fracture toughness decrease drastically after the length of flaw sensitivities for both materials. Also, the failure stress keeps on decreasing with an increasing notch length for both materials. Afterwards, a simple phenomenological relation is proposed for fitting experimental results under a pure shear loading with only two parameters. The mathematical relation is valid for both the materials and covers the notch sensitivity with a good agreement.

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Natural rubber is one of the most potential electro‐active polymers for sensors, actuators, and energy harvesting applications. Enhancing the characteristic properties of polymers by reinforcing with fillers that possess multifunctional attributes have attracted considerable attention. In the present study, barium titanate reinforced natural rubber composite is prepared by using two‐roll mill mixing. Afterwards, mechanical, electrical, and electromechanical properties of the composites are extensively analyzed by reinforcing different amounts of barium titanate into the matrix of natural rubber. The fabricated dielectric composite shows excellent properties such as high dielectric constant, low dielectric losses, high dielectric breakdown strength, and extreme stretchability. It is observed that as the filler loading reaches the value of 11 parts per hundred rubber (phr), maximum agglomeration of the particles occurs. Maximum stretchability and highest ratio of dielectric constant to elastic modulus are obtained at 8 phr of barium titanate fillers and at the loading, a maximum actuation strain of 11.24% is achieved. This study provides a simple, economical, and effective method for preparing enhanced mechanical, electrical, and electromechanical properties of natural rubber composites, facilitating the wide applications of dielectric materials as actuators and generators.

Heavy metal impurities in cosmetics are common due to their natural abundance. However, they should be kept to a minimum wherever technically feasible. Although human external contact with a substance rarely results in a significant systemic exposure, local exposure to cosmetics may pose a risk of heavy metal contamination. In this study, we sought to investigate the heavy metal concentration present in various cosmetic products from different brands and qualities that are available in the Saudi Market, also to analyze and compare the determined values relative to the reported permissible levels according to international standards. In this study, we have selected several facial cosmetics from the Saudi market and classified their quality into three main classifications based on their price. This was followed by an analysis and reporting of heavy metal content using an inductively coupled plasma–mass spectrometer. We found that three metals were below the permissible limits (Pb, As, and Cd) for cosmetics according to the Saudi Food and Drug Administration and Canadian Standards, besides (Cr) which was also below the limit of the United States Food and Drug Administration. The level of (Ni) exceeded the recommended range in the three-class classifications. On contrary, Pb, Cr, As, and Cd have all exceeded the acceptable levels based on European standards. Further assessment and careful selection of heavy metals content in cosmetics are urgently needed, as there are fluctuations in values between different international standards which might pose a potential harmful effect to human health from the daily use of cosmetics containing heavy metals impurities.