Experimental data in support of continuous microwave effect on emulsion polymerization of styrene

This article contains original experimental data, figures and methods to the study of Microwave-assisted emulsion polymerization of styrene under the frame of “Enhanced Microwave Synthesis” (EMS), has been examined to investigate the advantages of Microwave (MW) power use in emulsion polymerization (Ergan et al., Eur. Polym. J. 69, 2015, 374–384). For comparative purpose, MW and conventional heating (CH) method experiments were conducted under similar conditions. By externally cooling the reaction vessel with 1,4-dioxane, constant and continuous MW power was successfully applied at isothermal condition during the polymerization. Here we give the MW power calibration data of MW-experimental system, the complete set of the experimental polymerization data and the analysis data obtained from different polymer characterization test devices (GPC, DSC and Viscometer).


Value of the data
The data shows the successful application of continuous and constant MW power during the polymerization while maintaining isothermal condition as well.
The data provide suitable process conditions for achieving high yields of polystyrene by MWassisted emulsion polymerization.
The data provide the proofs for the existence of the "specific MW effect".

Data, experimental design, materials and methods
Styrene (M) received from Merck was purified with a freshly prepared solution of NaOH (0.0025 M) before using in order to eliminate the inhibitor in styrene. Then, styrene was washed with ultrapure water until the pH was 7. Other chemicals; 1,4-dioxane, Potassium persulfate (KPS), Hydroquinone, Sodium dodecyl sulfate (SDS) were used as received from Merck. Bi-distilled water was used in all the experiments.
In a typical run, 60 cm 3 water, SDS, KPS, and M mixture were load into the jacketed glass reactor and stirred at room temperature for a complete dissolution. Then, ultrasonic pre-treatment was preparation. Finally, emulsion droplet size distributions were obtained typically between 0.8 mm and 10 mm as shown in Fig. 1.
In this study, a multimode MW reactor (Start-S model, Milestone S.r.l. Sorisole, Italy) was used. During the runs, the Fluoroptic (FO) sensor (accuracy 70.2 1C, ATC-FO-300008 type, Zu electronic, Italy) was dipped in the reactor in a glass capillary sheath. By external circulation of 1,4-dioxane as coolant between jacketed glass reactor and cooling bath, continuous and constant MW energy was applied under isothermal conditions as in our previous studies [2][3][4]. So, our MW experimental system differs from the literatures which use the cooling system by "air cooling" [5][6][7][8] while applying discontinuous MW power [9][10][11]. A typical experimental plot with the temperature/MW power data received per 1 s time interval is shown in Fig. 2. The bold style indicate the "suitable experimental conditions" in each serial.

Calibration procedure and data of the microwave power output
According to the IEC 60705 standard method [12][13][14], empty jacketed glass vessel was weighed, filled with different amount of distilled water and placed into the MW reactor cavity. MW energy (P nom ) was supplied according to amount of water. The water was stirred along the heating period by a magnetic stirrer at 160 rpm. After 60 s, the final temperature of water was measured by Fluoroptic (FO) sensor. Absorbed MW power (P) by the vessel, water, magnet and 1,4-dioxane are calculated by means of Q¼mcΔT. The results were given in Table 1. To account for the differences between the  absorbed and nominal power values, a correction factor (p) is defined as "P/P nom " which is used to calculate the required P nom to achieve a given P value during the polymerization. Mean value of p was calculated as 0.608 under chosen experimental conditions and experimental system (reaction volume: 60 cm 3 ) used in this study.

Experimental data of MW-assisted emulsion polymerization of styrene
Six experimental variables given in Table 2 were investigated and suitable experimental conditions to achieve polymer yield 495% were determined as T ¼75 1C, SDS/M¼0.06, KPS/M ¼0.004, H 2 O/M¼6 and P ¼0.6 kW dm À 3 .

Experimental data of CH-emulsion polymerization of styrene
Five CH experiments were conducted also at the experimental conditions (T ¼75 1C, SDS/M¼ 0.06, KPS/M¼0.004, H 2 O/M¼6) at different reaction times. The results are presented in Table 3. The comparison of CH and MW experimental results at the same conditions demonstrate the advantage of MW application in term of polymerization time.

Polymer characterization data
MW and CH polymer samples synthesized at the same process conditions were found to have similar structural and thermal characteristics. The analysis data supplied by GPC, DSC and Viscosity instruments is shown in Table 4.