The redox initiator, cumene hydroperoxide/ tetraethylenepentamine (CHPO/TEPA), was used to initiate the emulsion polymerizations of styrene and methyl methacrylate (MMA). The hydrophobic CHPO acting as oxidizer would interact with the hydrophilic TEPA employed as the reducer at the particle-water interface where the vinyl monomer is present. The kinetics of the styrene and MMA polymerizations were studied under a temperature range of 30-70°C. The polymerization rate, the concentration of monomer in the particles, the average number of latex particles and the number of radicals per particle were investigated to evaluate the propagation rate constant during interval II of the polymerization. With increasing temperature, the number of latex particles increases while the monomer concentration in the particles slightly decreases. The observed number of radicals per particle, calculated from the number average volume of the particles and the relation between the entry rate coefficients of free radicals into the particles and the exit rate coefficients of free radicals from the particle, was found to be approximately 0.47 and 0.5 in case of styrene and MMA polymerization, respectively. The calculation shows that the propagation rate constant, k p = 6.84 × 10 7 e −37.65/RT and k p =3.4×10 7 e −31.05/RT L/mol s for styrene and MMA polymerizations over the temperature range studied, respectively.

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This research aimed to design an instructional module to teach light diffraction by a grating to secondary students applying a science, technology, engineering, and mathematics (STEM)-integrated approach. Based on this approach, instructional management integrated the disciplines of physics and mathematics with engineering design process principles, while information searches, assessment, and evaluation drew on technology. The module involved working out a solution to the real-world scientific problem of constructing a spectroscope in the environment of cooperative learning. Upon completion of the module, the students were expected to demonstrate a thorough understanding of light diffraction by the grating as well as problem-solving skills. To evaluate its effectiveness, the module was trialed on thirty 11th grade students in a Thai school in Pathum Thani, Thailand. The findings revealed that the implementation of the module enabled the students to achieve a statistically higher post-test score than that for the pre-test at the significance level of 0.05. As a result of the module, the students also exhibited a high level of academic development, as indicated by the class normalized gain of 0.82. Finally, the module was perceived by the students as being suitable for their level, offering them a chance to apply classroom knowledge to authentic problems and hence accumulating their hands-on experience, enhancing their problem-solving skills through the application of the engineering design process, and improving their team-working ability.

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