Preparation and Performance of PE⁃HD/PE⁃UHMW Blends by Ultrasonic⁃assisted Twin⁃screw Extrusion

doi:10.19491/j.issn.1001-9278.2020.08.002

Abstract

Abstract:

Ultra high molecular weight polyethylene (PE-UHMW) and high density polyethylene (PE-HD) have a similar molecular composition and structure, and therefore they have relatively good compatibility. In this paper, the PE-HD/PE-UHMW blends were prepared by ultrasonic-assisted twin-screw extrusion, and the effect of PE-UHMW content on the crystallization behavior, compatibility and final mechanical properties of the blends was investigated. The results indicated that the PE-UHMW phase achieved a uniform dispersion without phase separation in the PE-HD matrix at the content lower than 2.0 wt%. As the content of PE-UHMW increases, there is a significant increase in nucleation number for the PE-UHMW domain, which is beneficial to crystallization. Moreover, the degree of entanglement also increases gradually with an increase of PE-HD content. This makes more PE-HD molecules involved in the chain?folding crystallization with the nucleus formed by PE-UHMW, leading to a gradual increase of crystallinity. As a result, the yield strength, breaking strength and elongation at break of the blends were improved significantly with an increase of PE-UHMW content.

Key words: polyethylene, rheology, crystallization kinetics, mechanical property

CLC Number:

TQ325.1⁺2

Yanxiao LI, Yan ZHANG, Xuelian HE. Preparation and Performance of PE⁃HD/PE⁃UHMW Blends by Ultrasonic⁃assisted Twin⁃screw Extrusion[J]. China Plastics, 2020, 34(8): 9-16.

Figures/Tables 14

样品名称	PE?HD的含量/%	PE?UHMW的含量/%
H/UH300?0.5	99.5	0.5
H/UH300?1.0	99.0	1.0
H/UH300?1.5	98.5	1.5
H/UH300?2.0	98.0	2.0

Tab.1. The mass ratio of PE?HD/PE?UHMW in the blends

Fig.1. The scheme of the ultrasonically?aided twin screw extruder

Fig.2. SSA program

Fig.3. G' and G" of H/UH300 composites versus frequency

Fig.4. Complex viscosity of H/UH300 blends versus frequency

Fig.5. Van Gurp curves for the H/UH300 composites with different PE?UHMW content

Fig.6. Han curves for the blends of H/ UH300

Fig.7. The Cole?Cole plot for the H/UH300 composites

Fig.8. The isothermal crystallization curves and Avrami plots of H/UH300 composite at 116 ℃

样品	115 ℃			116 ℃
样品	n	K	L_c/nm	n	K	L_c/nm
PE?HD	2.24	0.52	23.7	1.89	2.18	23.7
H/UH300?0.5	2.30	0.58	25.9	1.90	2.28	25.4
H/UH300?1.0	2.32	0.61	27.3	1.94	2.36	27.6
H/UH300?1.5	2.41	0.78	27.8	2.14	2.29	27.3
H/UH300?2.0	3.32	1.56	28.3	2.34	3.77	28.5

Tab.2. K, n and Lc of the composites at the cooling rate of 115 ℃ and 116 ℃

Fig.9. The SSA curves of the composites

Fig.10. The lamellar thickness and distribution of the composites

Fig.11. SEM of the H/UH300 blends

样品	屈服强度/MPa	断裂强度/MPa	断裂伸长率/%
PE?HD	28.3	17.2	120
H/UH300?0.5	32.4	20.5	760
H/UH300?1.0	29.0	18.6	600
H/UH300?1.5	29.2	18.6	590
H/UH300?2.0	29.4	19.2	550

Tab.3. Mechanical properties of PE?HD/PE?UHMW blends

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