In this study, graphene oxide (GO) was synthesized by the improved Hummers’ method. The degree of oxidation from graphite (Gi) to GO was determined through interlayer spacing calculated from X–ray diffraction. Besides, the effect of KMnO4: Gi ratios (X1), H2SO4 volume (X2), oxidation temperature (X3), oxidation time of stage 1 (X4), and oxidation time of stage 2 (X5) was screened by the Plackett–Burman model. The simultaneous impact of three factors that influenced the degree of oxidation (X1, X2, and X3) was studied by the Box–Behnken experimental model of response surface methodology to achieve suitable conditions for the GO synthesis process. The characterization of GO product was investigated via the modern analytical methods: X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Inaddition, the study was also carried out on a pilot scale for orientation in industrial application with the yield of 14 g/batch.

This study presents an exploratory investigation of SMEs in Vietnam to understand the impact of personal-level factors on middle managers’ work motivation and the moderating role of work environment. A survey of 450 middle managers (MMs) in 150 Hanoi’s SMEs was conducted. The findings of this research showed a significant positive impact of Achievement (ACHV), Recognition (RECOG), and Responsibility (RESP) on work motivation of MMs under the investigation. Furthermore, the result indicated that the work environment affects the relationship between personal-level factors and work motivation of participants. Consequently, both work environment improvement and strategies related to personal-level factors need to be taken into consideration. Especially, Recognition and transparency in Responsibility are appreciated in organizations with a low level of work environment satisfaction. However, there were no indications that Participation (PAR) and Communication (CMM) have a considerable impact on work motivation of respondents, being neither low level nor high level of work environment satisfaction. Based on the findings, recommendations are suggested for Vietnam’s SMEs to improve work motivation of MMs, by (i) developing standards with emphasis on their achievement, (ii) paying attention to organizational culture focusing on the responsibility of this managerial level, and (iii) building an adequate incentive system, especially non-financial incentives.