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中南大学学报(英文版)

Journal of Central South University

Vol. 25    No. 12    December 2018

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Transformation of β to α phase of isotactic polypropylene nucleated with nano styrene butadiene rubber-based β-nucleating agent under microwave irradiation
Nawadon PETCHWATTANA1, Phisut NAKNAEN2, Jakkid SANETUNTIKUL3

1. Division of Polymer Materials Technology, Faculty of Agricultural Product Innovation and Technology, Srinakharinwirot University, Ongkharak, Nakhon Nayok 26120, Thailand;
2. Division of Food Science and Nutrition, Faculty of Agricultural Product Innovation and Technology, Srinakharinwirot University, Ongkharak, Nakhon Nayok 26120, Thailand;
3. Faculty of Engineering and Technology, King Mongkut''s University of Technology North Bangkok, Bankhai, Rayong 21120, Thailand

Abstract:This paper investigates the effect of microwave irradiation on the β to α phase transformation of the β-nucleated isotactic polypropylene (iPP). Ten microwave irradiation cycles was applied to the iPP and iPP modified with 0.3 wt% and 0.5 wt% β-NA, and the data at 2nd, 4th, 6th, 8th and 10th irradiation were reported. As expected, the sample temperature was found to increase with the irradiation time, by more than 130 °C, due to high frequency of microwave processing. This was the major factor that induced the β-phase transformation and structural change. Both the differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results indicated that β-phase was mainly transformed to α-phase and partially converted to the amorphous section. It was reflected as 1) the reduction of the enthalpy of β-crystal melting (DH), 2) the increased enthalpy of α-crystal melting (DH), 3) the decreased β-crystalline phase fraction (Kβ) and 4) the decrease of the overall degree of crystallinity (Xall). Under impact force, neat iPP showed a slight increase in the impact strength with the irradiation time, due to the increase of amorphous region. For the β-iPP, it decreased due to the reduction of the β-phase content.

 

Key words: polypropylene; crystallization; mechanical properties; thermal properties

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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