Preparation, Characterization and Application of Silica Nanoparticle Micro-aggregates with Circular Structure†

doi:10.7503/cjcu20150510

Abstract

Abstract:

Silica sol was firstly prepared by means of sol-gel method and then dried by spray drying method. Scanning electronic microscope(SEM) results demonstrated that the initially obtained nanoparticles were recomposed to monodispersed circular aggregates with size about 20 μm. The silica/polypropylene(PP) composite was prepared and investigated by means of differential scanning calorimetry(DSC), polarizing microscopy(POM), wide angle X-ray diffraction(WAXRD) and transmission electron microscopy(TEM). The micron circular aggregates, PC16MS, broke up and re-dispersed into nanoparticles with size less than 200 nm in the PP matrix during melt-compounding. The effect of the addition of PC16MS on spherulite growth of iPP was investigated using POM. The results demonstrated that the addition of PC16MS can significantly accelerate the primary nucleation process, minimize the spherulite radius and shorten the crystallization time. A linear relationship was observed between the radius of spherulites and crystallization time at the initial stage of crystallization. With the addition of 2%(mass fraction) PC16MS, the crystallization temperature increased by 10.4 ℃ and the nucleation efficiency reached 39.1% compared to pristine iPP, suggesting PC16MS can be used as an effective nucleating agent for PP.

Key words: Silica nanoparticles, Spray drying, Polypropylene, Crystallization

CLC Number:

TrendMD:

TIAN Min, YANG Yingjuan, HE Wentao, LI Juan, QIN Shuhao, YU Jie. Preparation, Characterization and Application of Silica Nanoparticle Micro-aggregates with Circular Structure^†[J]. Chem. J. Chinese Universities, 2016, 37(1): 180.

Figures/Tables 12

Fig.1 Principle of spray drying

Fig.2 Size distribution and TEM image(inset) of colloidal silica nanoparticles

Fig.3 Digital photos of the dried PC16MS(A) and NC16MS(B)

Fig.4 SEM images of PC16MS(A—D) and NC16MS(E)^(B) Partial view of (A); (C) partial view of (B); (D) re-dispersed in alcohol by ultrasonic and then dried on copper.

Fig.5 Nitrogen sorption isotherms of PC16MS

Fig.6 TEM images of NC16MS/PP and PC16MS/PP composites ^ (A) 0.2%PC16MS; (B) 2%PC16MS; (C) 2%NC16MS.

Scheme 1 Formation of SiO2 aggregating and their re-dispersion by melt blending

Fig.7 WXRD patterns of pure PP(a), 1.25%CTAB/PP(b), 2%NC 16MS/PP(c) and 0.2%PC16MS/PP(d) and 2%PC16MS/PP(e) composites

Table 1 Crystalline parameters of PP and nucleated PP

Sample	T_c/℃	T_m/℃	H_m/(J·g^-1)	X_c(%)	NE(%)
PP	111.39	164.85	90.94	43.51	0
0.2%PC16MS/PP	112.08	165.02	91.49	43.78	2.6
2%PC16MS/PP	121.79	164.43	94.18	45.06	39.1
2%NC16MS/PP	114.65	164.48	94.46	45.20	12.3

Fig.8 DSC heating(A) and cooling(B) thermograms for neat PP(a), 0.2%PC16MS(b), 2%PC16MS(c) and 2%NC16MS(d)

Fig.9 Polarized optical microscope images of PP(A1—A4), 0.2%PC16MS/PP(B1—B4), 2%PC16MS/PP(C1—C4) and 2%NC16MS/PP(D1—D4) composites^(A1—A4) are the POM photographs of PP on crystallizing at 15, 60, 105 and 150 min, respectively; (B1—4—D1—4) represent the crystallization time at 5, 7.5, 10 and 12.5 min, respectively.

Fig.10 Nucleation density calibrated by the volume measured area in the POM(A) and the spherulite radius plotted(B) against the crystallization time for PP , NC16MS/PP and PC16MS/PP composites

References 15

[1]	Jain S., Goossens H., van Duin M., Lemstra P., Polymer,2005, 46(20), 8805—8818
[2]	Nitta K., Asuka K., Liu B., Terano M., Polymer,2006, 47(18), 6457—6463
[3]	Asuka K., Liu B., Terano M., Nitta K. H., Macromol. Rapid Comm., 2006, 27(12), 910—913
[4]	Sun D. H., Zhang R., Liu Z. M., Huang Y., Wang Y., He J., Han B. X., Yang G. Y., Macromolecules,2005, 38, 5617—5624
[5]	García M., Van V. G., Jain S., Schrauwen B. A. G., Sarkissov A., Van Zyl W. E., Boukamp B., Rev. Adv. Mater. Sci., 2004, 6, 169—175
[6]	Wu L. B., Cao D., Huang Y., Li B. G., Polymer,2008, 49, 742—748
[7]	Li J., Qin S. H., He W. T., Xiang Y. S., Zhang Q., Zhang K., Zhang M. M., Zhou Y., Yu J., J. Polym. Eng., 2015, 35(6), 565—573
[8]	Urata C., Aoyama Y., Tonegawa A., Yamauchi Y., Kuroda K.,Chem. Commun., 2009, (34), 5094—5096
[9]	Nandiyanto A. B. D., Okuyama K., Adv. Powder Technol., 2011, 22(1), 1—19
[10]	Iskandar F., Gradon L., Okuyama K., J.Colloid Interface Sci., 2003, 265, 296—303
[11]	Sing K., Colloids Surf. A: Physicochem. Eng. Asp., 2001, 187/188, 3—9
[12]	Hu J. S., Kong B., Chao C. Y., Sun J., Chem. J. Chinese Universities, 2009, 30(6), 1253—1255
	(胡建设, 孔波, 钞春英, 孙静. 高等学校化学学报, 2009, 30(6), 1253—1255)
[13]	Gahleitner M., Grein C., Kheirandish S., Wolfschwenger J., Int. Polym. Proc., 2011, 26(1), 2—20
[14]	Lin Z., Huang Z., Zhang Y., Mai K., Zeng H., J. Appl. Polym. Sci., 2004, 91(4), 2443—2453
[15]	Xu W., Ge M., He P., J. Polym. Sci. Part B: Polym. Phys., 2002, 40(5), 408—414