実験番号：201901020（2 シフト）

BL8S3

iso-ポリプロピレンの結晶化過程の観察
Supanont Jamornsuriya1，Visit Vao-soongnern1, 岡本茂 2
1 Suranaree University of Technology, Thailand，2 名古屋工業大学
Keywords：polypropylene，ethylene defect，crystallization
1．Background and Objective
Isotactic polypropylene (iPP) has been commercially for several decades after the discovery of Ziegler-Natta(ZN) catalysts. iPP is one of the most widely used industrial plastics, as it possesses excellent thermal andmechanical properties, as well as thermal resistance. The physical properties of iPP products can be tailored bymanipulating their crystal structure through the control of tacticity, molecular weight (MW), molecular-weight
distribution (MWD) and copolymerization with different monomer. The main objective of this work is to study theeffect of ethylene defect on the crystallization characteristics of iPP with small fraction of ethylene content usingsynchrotron X-Ray techniques. The crystallization kinetics and crystal morphology were investigated by in-situ
isothermal crystallization using simultaneous synchrotron small-angle X-ray scattering (SAXS) and wide-angle
X-ray diffraction (WAXD). Several quantitative parameters were extracted and analyzed in details based on thetwo-phase model of stacked lamellae.
2．Experiments
Five isotactics polypropylene samples with different amount of ethylene defects were used for SAXS andWAXD measurement with X-Ray of 0.15 nm wavelength. The samples were heated from the room temperature to
180oC and held for 2 min to erase thermal history. Then, they were rapidly cooled down (at the rate =100oC/min) to crystallization temperature at 130oC untill the crystallization process were done. The isothermal
measurements were started at 130 oC using 1 second explosure time with 2 seconds interval (1 measurement perevery 3 second). The sample to detector distance is 2.1 m and 64.1 mm for SAXS and WAXD, respectively.
3．Results and Discussion
Preliminary results of SAXS profiles for isothermal crystallization of polypropylene samples are depicted in theFigure (the sample in this report is RPP05 containing 0.59% of ethylene defect). The results show that theinduction period for the crystallization process takes about
10 min. For the sample with lower ethylene defect content(0.09% for RPP01), the induction period is decreased toonly 3 min. These results suggest that the higher ethylene
defect, the lower the crystalization kinetics. In addition,
the crystal structure parameters were investigated using theanalysis of 1-D electron density correlation function. For
RPP05 sample, the average long period distance (Lp) andthe average crystall lamellar thickness (Lc) are 18.36 nm.
and 6.35 nm, respectively. Compared to the sample withlower ethylene content (RPP01), these parameters becomelarger i.e. Lp = 18.46 nm and Lc = 6.76 nm. These results
suggest that the higher ethylene content, the smaller crystal lamellae are formed. The on-going data analysis isabout the WAXD measurement which we plan to study later.
4．References
1．Rungswang, W. et al. Influences of Tacticity and Molecular Weight on Crystallization Kinetic and Crystal
Morphology under Isothermal Crystallization: Evidence of Tapering in Lamellar Width.”, Polymer (2019) 172,
41-51.