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This paper aims to study the thermal oxidation performance of antioxidant additives in ester base oils deeply.

ReaxFF molecular dynamics was used to simulate the thermal oxidation process of butyl octyl diphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate as two antioxidant additives act on the Trimethylolpropane trioleate (TMPTO) base oil. Meanwhile, combining with the infrared spectroscopy characterization results of the thermal oxidation test, this paper provides theoretical support for the development of high-performance synthetic lubricants and their antioxidant additives.

The results show that butyl octyldiphenylamine easily removes the hydrogen atom on the secondary amine, which promotes the formation of more long carbon chain diene radicals or polyene hydroperoxides from TMPTO. Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate could easily decompose into octadecyl hydroperoxide and 2,6-di-tert-butyl 4-propionylphenol, which could convert into 2-tert-butyl-4-peroxyethyl-6-hydroperoxy-tert-butylphenol in the middle of the thermal oxidation reaction, prompting TMPTO to form more short-chain alkenyl and olefin hydroperoxide or other oxide.

The main change characteristics of base oil molecules are the first thermal decomposition to form oleic acid groups and ethane cyclopropane methyl oleate. Under the action of butyl octyldiphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate, the deep oxidation and decomposition reaction are slowed down.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0037/

The emission from marine engines has a crucial effect on energy economy and environment pollution. One of the effective emission reduction schemes is to minimize the friction loss of main friction pairs such as cylinder liner-piston ring (CLPR). Micro-groove textures were designed to accomplish this aim.

The authors experimentally investigated the effects of micro-groove textures at different cylinder liner positions. The micro-groove texture was fabricated on samples by chemical etching and cut from the real CLPR pair. Sliding contact tests were conducted by a reciprocation test apparatus.

The average friction coefficient of grooves at 30° inclination were reduced up to 58.22% and produced better tribological behavior at most conditions. The operating condition was the critical factor that determined the optimum texture pattern. The surface morphology indicated that textures could produce smoother surfaces and less scratches as compared with the untextured surface.

Inclined grooves and V-grooves were designed and applied to real CLPR pairs. The knowledge obtained in this study will lead to practical basis for tribological design and manufacturing of CLPR pair in marine diesel engines.

The purpose of this paper is to explore the emergence of civil disobedience (CD) movements in Hong Kong in the context of the notion of civil society (CS).

The paper begins by rigorously defining the notion of CD, as well as the concept of CS and tracing its development in Hong Kong over the past several decades. By using a model of CS typology, which combines the variables of state control and a society’s quest for autonomy (SQA), the paper aims to outline the historical development of CD movements in Hong Kong. It also discusses the recent evolution of CS and its relationship with CD movements, particularly focusing on their development since Leung Chun-ying became the Chief Executive in 2012. Finally, by using five cases of CD witnessed in the past several decades, the relationship between the development of CS and the emergence of CD in Hong Kong has been outlined.

Four implications can be concluded: first, CD cannot emerge when the state and society are isolated. Second, the level of SC and the scale of CD are positively related. Third, as an historical trend, the development of SQA is generally in linear progress; SQA starts from a low level (e.g. interest-based and welfare-based aims) and moves upwards to campaign for higher goals of civil and political autonomy. If the lower level of SQA is not satisfied, it can lead to larger scale CD in future. Fourth, the CD movement would be largest in scale when the state-society relationship confrontational and when major cleavages can be found within CS itself.

This paper serves to enrich knowledge in the fields of politics and sociology.