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Firstly, into a 250 ml four-necked round-bottom flask fitted with a mechanical overhead stirrer, coupled with a condenser, drop funnel, different content of MLCB (relative to the weight of styrene monomer) that dispersed in 50 ml deionized water by ultrasonic was introduced into the flask, and a certain dosage of PVA was added, then the system was heated to 92 [degrees] C.
When MLCB was homogeneously dispersed in the suspending medium, the stirrer speed was turned up to 440 rpm, and the system was heated to 85 [degrees] C gradually.
The particle sizes of MLCB in the presence of different PVA dosage were measured by dynamic light scattering (DLS) with a Malven zetasizer 3000 HSA particle sizer.
Effect of the PVA Dosage on the Mean Size of MLCB To systematically investigate the effect of the PVA dosage on the mean size of MLCB, the MLCB amount was fixed at 0.02 g, and different dosage of PVA was charged according to the above first step of in situ suspension polymerization.
In addition, we had synthesized a series of PS/MLCB composite particles with different MLCB content in the absence of PVA in our previous report (34).
3c showed the relationship between the MLCB content and optimum PVA dosage, the PVA dosage decreased with the increase of MLCB content.
To further elucidate the effect of PVA dosage on the macromorphology and black luster of resultant PS/MLCB composite particles, a series of experiments were carried out at a given MLCB content of 0.2 wt% by varying the PVA dosage according to the recipe of sample 5 in the Table.
4, it's concluded that further increase of PVA dosage would result in the deterioration of surface morphology and black luster, which was ascribed to the interaction between the MLCB and PVA, and the interaction became stronger with the increasing dosage of PVA.
To investigate the effect of MLCB on the thermal stability of the resultant PS/MLCB in the present of PVA, TGA measurement was thus employed.
When compared with the PS/MLCB composite particle that synthesized in the absence of PVA in our previous report (34), the PS/MLCB composite particle that achieved in the presence of PVA possessed a larger [M.sub.w] and [M.sub.n], and a narrower [M.sub.w]/[M.sub.n], it was attributed to the interaction between PVA and MLCB, by which the inhibition group was covered and the inhibition phenomenon was eliminated or weakened.
However, when residual weight% was 80%, the decomposition temperature of PS/MLCB was about 50[degrees]C higher than that of pure PS and shifted to a higher temperature with the increment of MLCB. When residual weight% was 50%, the decomposition temperature of PS/MLCB was about 22[degrees]C higher than that of pure PS, which demonstrated that PS/MLCB exhibited a better thermal stability than that of pure PS.
8a) of PS/MLCB was very smooth, which indicated that the combination of PS and MLCB was well.
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