No abstract

No abstract

The increase of health and environmental consciousness has motivated the effort of technology improvement on lubrication by finding and exploring another potential alternative to replace mineral-based metalworking fluids. Due to this concern, vegetable-based oils have been recognised as an ideal lubricating base oil in machining due to low toxicity, biodegradable, and renewable energy sources. Moreover, nanofluids have attracted enormous attention in the field of lubrication due to excellent physical and chemical properties that can enhance tribological characterisation. The objective of the current work is to develop a new formulation of nanofluids in modified jatropha oil (MJO) by adding hexagonal boron nitride (hBN) and graphene nanoparticle additives at the lowest concentration (0.01, 0.025. and 0.05 wt. %). The physicochemical tests in terms of kinematic viscosity and viscosity index were conducted and compared with synthetic ester (SE). Tribology testing was conducted through four-ball test to determine the coefficient of friction, mean wear scar diameter, and friction torque. The result shows a significant improvement of MJO samples by adding nanoparticle additives compared to the SE. MJOg2 (MJO + 0.025 wt. % of graphene) exhibited excellent tribological behaviour by providing the lowest coefficient of friction and friction torque. Meanwhile, MJOh1 (MJO + 0.01 wt. % of hBN) provided with a smaller mean wear scar diameter among other lubricant samples. Conclusively, the addition of nanoparticle additives significantly enhanced the tribological characteristics and is highly suitable as a substitute for SE.

No abstract

No abstract

a b s t r a c tSynthetic amorphous silica (SAS) like NM-200 is used in a wide variety of technological applications and consumer products. Although SAS has been widely investigated the available reproductive toxicity studies are old and do not cover all requirements of current OECD Guidelines. As part of a CEFIC-LRI project, NM-200 was tested in a two-generation reproduction toxicity study according to OECD guideline 416. Male and female rats were treated by oral gavage with NM-200 at dose levels of 0, 100, 300 and 1000 mg/kg bw/day for two generations. Body weight and food consumption were measured throughout the study. Reproductive and developmental parameters were measured and at sacrifice (reproductive) organs and tissues were sampled for histopathological analysis. Oral administration of NM-200 up to 1000 mg/kg bw/day had no adverse effects on the reproductive performance of rats or on the growth and development of the offspring into adulthood for two consecutive generations. The NOAEL was 1000 mg/kg body weight per day.

Nonedible vegetable-based oil was recently explored due to the demand for a sustainable element in a machining process. The aim of this study is to critically analyse the tribological performance of nanofluid from nonedible (modified jatropha oil, MJO) nanofluid added with activated carbon nanoparticles. The tribology test was conducted through four-ball test using various concentration ratios of nanoparticles. According to the findings, MJOa2 (0.025wt.% activated carbon in MJO) showed the lowest coefficient of friction and mean wear scar diameter, produced a smoother surface with low surface roughness value, followed by MJOa3 (0.05wt.% activated carbon in MJO), MJOa1 (0.01wt.% activated carbon in MJO) and synthetic ester (SE). Therefore, MJOa2 was considerably suitable for metalworking fluid application which emphasizing the element of sustainability.

No abstract