The influence of the weight ratio of a castor oil modified epoxy resin (CE) and an epoxidiacrylate resin (EDA) on photocrosslinking and properties of the coatings containing these resins, hexandioldiacrylate monomer (HDDA) and photoinitiator Darocur 1173 (D.1173) upon UV‐exposure have been studied. The variation of acrylate groups during the photoinitiated polymerization was evaluated by FTIR analysis. The crosslinking of the UV‐cured coatings was proved by gel fraction and swelling degree determinations. In addition, some of the properties of the UV‐cured coatings such as relative hardness, flexibility, impact resistance, adhesion onto steel plates and gloss have also been examined. It was shown that the increase of the CE/EDA ratio from 10/40 to 40/10 in investigated coatings led to the decrease of the conversion rate of acrylate groups, and significantly changed some properties of the cured coatings after 14.4 s of UV irradiation: Decrease of gel fraction from 96 to 61 %, but improved the flexibility from 10 to 3 mm, impact resistance from 40 to 140 kG.cm, adhesion from 5 to 2 points. The gloss of the coatings remained to be 100 % in all cases. Long hydrocarbon chains of castor oil residue in CE, lower reactivity of double bonds and radicals formed in the chains compared with those of acrylate groups have been attributed to the obtained relationship between the CE/EDA ratio and photocrosslinking, properties of the cured coatings.

This study aims to explore English as a Foreign Language (EFL) students’ understanding and perceptions of applying critical thinking to their practice of speaking skills. Although some research papers have been implemented to understand the impact of critical thinking on learners’ language skills, the study specifically investigates how critical thinking can affect speaking ability amongst learners of low-English levels who are from a non-English-speaking country, according to their perceptions. The participants are 190 undergraduate students whose English proficiency was pre-intermediate and who were enrolled in English for IELTS preparation programs at the Creative Language Center (CLC) of Ton Duc Thang University, Vietnam. A survey was sent to collect information about students’ learning experiences and opinions on their performance of speaking skills integrated with critical thinking. The findings highlighted some challenges when students used critical thinking while practicing oral communication skills, including their habits of learning and insufficient opportunities to practice the skills. Also, students’ awareness of the important role of critical thinking in improving their speaking performance and confidence was successfully noted.

The influence of Darocur 1173 (D.1173) photoinitiator content on the photocrosslinking of the coatings based on an epoxy diacrylate oligomer (EDA), hexanediol diacrylate monomer (HDDA) and properties of UV cured coatings have been studied. The fast conversion of acrylate groups and UV crosslinking of the coatings were shown by IRspectroscopy analysis and gel fraction determination, respectively. It was found that there was an optimal relationship between conversion of acrylate groups, as well as the hardening rate of the coatings and contents of D.1173, ranging from 0 to 2 % of total amount of EDA and HDDA, under UV exposure. The optimal content of D.1173 was determined to be 1 % and the UV curing of the coating having the weight ratio of the constituents EDA/HDDA/D.1173 = 50/50/1 occurred very fast, leading to formation of a high performance UV cured coating which can be used in different sectors of applications as decorative, protective coatings or adhesives.