基于静电分选解析聚乙烯颗粒生长与形貌演变

doi:10.11949/0438-1157.20211838

摘要/Abstract

摘要：

解析聚烯烃颗粒生长过程的形貌演变规律对认识聚合反应机理和调控产品性能至关重要。然而，聚烯烃复杂的颗粒生长行为导致极宽的粒径分布和较大的形貌差异，现有研究关注形貌均一的催化剂破碎生长成初级聚烯烃的过程，缺少对形貌各异的初级聚烯烃后续生长和形貌演化的系统研究。此外，亟需一种能够批量分选不同形貌聚烯烃的手段，支撑聚烯烃颗粒生长形貌的统计解析。基于同质同粒径颗粒摩擦荷电的形貌依赖性，开发了聚烯烃颗粒静电-形貌协同分选技术，实现了尺寸相近的不同形貌聚烯烃颗粒的批量分选，并基于此考察了聚乙烯颗粒生长过程中形貌的分化与演变规律。结果显示，聚乙烯颗粒生长过程中存在普遍的形貌劣化现象，随着粒径增大，颗粒形貌逐渐偏离标准球形；颗粒粒径、形貌、结晶度等的耦合解析表明聚乙烯颗粒存在两种可能的颗粒生长模式和形貌劣化路径：结晶速率过快导致的颗粒破碎和催化剂形貌复制效应导致的形貌劣化。研究方法和结果可为聚烯烃形貌研究和开发高性能聚烯烃催化剂提供重要支撑。

关键词: 聚乙烯, 静电, 形貌, 流化床, 聚合, 粉体技术

Abstract:

Analyzing the morphology evolution of polyolefin particles during the growth process is crucial for understanding the polymerization mechanism and regulating product properties. The complex particle growth of polyolefins leads to a large morphology difference and an extremely wide range of particle size distribution. However, existing studies focus on the process of primary polyolefins growing from the fragmentation of homogeneous catalysts, but lack of systematic studies on the subsequent growth and morphology evolution of primary polyolefins with different morphologies. Besides, a method of batch sorting polyolefin with different morphologies is needed to support statistical analysis of morphology evolution. An electrostatic-morphology co-separation method for polyolefin particles was developed based on the morphology-dependence of same-material particles with the same size. Through this method, batch sorting of polyolefin particles with similar sizes but different morphologies was achieved and the morphology evolution during polyethylene particle growth was investigated. The results show that there is a general phenomenon of morphology deterioration during polyethylene particle growth. As the particle size increases, the particle morphology gradually deviates from the sphere. The coupling analysis of particle size, morphology and crystallinity indicates two possible modes of particle growth as well as morphology deterioration: the particle fragmentation caused by excessive crystallization rate, and the replication of catalyst morphology. The method and results in this paper provide important support for the study of polyolefin morphology and the development of high-performance polyolefin catalysts.

Key words: polyethylene, electrostatics, morphology, fluidized-bed, polymerization, powder technology

中图分类号:

TQ 325.12

葛世轶, 杨遥, 黄正梁, 孙婧元, 王靖岱, 阳永荣. 基于静电分选解析聚乙烯颗粒生长与形貌演变[J]. 化工学报, 2022, 73(4): 1585-1596.

Shiyi GE, Yao YANG, Zhengliang HUANG, Jingyuan SUN, Jingdai WANG, Yongrong YANG. Analyzing particle growth and morphology evolution of polyethylene based on electrostatic separation[J]. CIESC Journal, 2022, 73(4): 1585-1596.

图/表 14

图1 实验装置

Fig.1 Schematic diagram of fluidized bed and electrostatic separator

表1 聚乙烯颗粒的性质

Table 1 Properties of polyethylene particles

颗粒	商业牌号	类型	催化剂	密度/(kg/m³)	熔融指数/(g/10 min)
PE-A	QHM32	HDPE	Metallocene	937	0.6
PE-B	QHM22	HDPE	Metallocene	937	0.6
PE-C	DMG1820	LLDPE	Ziegler-Natta	918	2.0
PE-D	DGDB2480	HDPE	Chromium	945	0.46

图2 粒径600~850 μm的聚乙烯正电颗粒和负电颗粒的SEM图像和圆形度

Fig.2 SEM images and circularity of positively and negatively charged PE particles of 600—850 μm

表2 圆形度及对应的颗粒投影图像

Table 2 Circularity and corresponding projection images

Circularity	Typical images
0.93—0.94
0.92—0.93
0.91—0.92
0.90—0.91
0.89—0.90
0.88—0.89

图3 聚乙烯颗粒各个窄粒径段的整体圆形度和静电分选正负荷电颗粒的SEM图像

Fig.3 Circularity of PE particles with various narrow PSDs and SEM images of positively and negatively charged particles by electrostatic separation

图4 四种牌号聚乙烯颗粒各窄粒径样品的中位径D50与中位圆形度ψ50

Fig.4 Median diameter and median circularity of four kinds of PE particles with various narrow PSDs

图5 四种牌号聚乙烯各窄粒径分布正电颗粒和负电颗粒的熔融焓

Fig.5 Melting enthalpy of positively and negatively charged particles with various narrow PSDs for four grades of PE

图6 聚乙烯颗粒破碎机理示意图[8]

Fig.6 Schematic diagram of nascent PE particle fragmentation

图7 不同形貌的聚乙烯颗粒的力-位移曲线

Fig.7 Force-displacement curves of PE particles with different morphology

图8 AFM测定的PE-A颗粒的杨氏模量

Fig.8 Elasticity modulus of PE-A particles measured by AFM

图9 PE-A粗糙颗粒的拉曼谱图（r/r0=1.0）

Fig.9 Raman spectra of rough PE-A particles (r/r0=1.0)

图10 PE-A颗粒剖面拉曼谱图的表面结晶度

Fig.10 Surface crystallinity of Raman spectra for PE-A particle profiles

图11 聚乙烯颗粒生长模式示意图

Fig.11 Schematic diagram of particle growth pattern of polyethylene

图12 聚乙烯PE-E颗粒的SEM图和对应的催化剂SEM图

Fig.12 SEM images of PE-E particles and its catalyst

参考文献 43

1	Alizadeh A, McKenna T F L. Particle growth during the polymerization of olefins on supported catalysts. Part 2: Current experimental understanding and modeling progresses on particle fragmentation, growth, and morphology development[J]. Macromolecular Reaction Engineering, 2018, 12(1): 1700027.
2	Cecchin G, Morini G, Pelliconi A. Polypropene product innovation by reactor granule technology[J]. Macromolecular Symposia, 2001, 173(1): 195-210.
3	Hutchinson R A, Ray W H. Polymerization of olefins through heterogeneous catalysis. IX. Experimental study of propylene polymerization over a high activity MgCl₂-supported Ti catalyst[J]. Journal of Applied Polymer Science, 1991, 43(7): 1271-1285.
4	Hock C W. How TiCl₃ catalysts control the texture of as-polymerized polypropylene[J]. Journal of Polymer Science Part A-1: Polymer Chemistry, 1966, 4(12): 3055-3064.
5	Wristers J. Direct examination of polymerization catalyst by electron scanning microscopy[J]. Journal of Polymer Science Part A-2: Polymer Physics, 1973, 11(8): 1619-1629.
6	Chen Y, Liu X G. Modeling mass transport of propylene polymerization on Ziegler-Natta catalyst[J]. Polymer, 2005, 46(22): 9434-9442.
7	Harshe Y M, Utikar R P, Ranade V V. A computational model for predicting particle size distribution and performance of fluidized bed polypropylene reactor[J]. Chemical Engineering Science, 2004, 59(22/23): 5145-5156.
8	McKenna T F L, di Martino A, Weickert G, et al. Particle growth during the polymerisation of olefins on supported catalysts, 1-nascent polymer structures[J]. Macromolecular Reaction Engineering, 2010, 4(1): 40-64.
9	Pater J T M, Weickert G, Loos J, et al. High precision prepolymerization of propylene at extremely low reaction rates—kinetics and morphology[J]. Chemical Engineering Science, 2001, 56(13): 4107-4120.
10	Ciardelli F, Altomare A, Michelotti M. From homogeneous to supported metallocene catalysts[J]. Catalysis Today, 1998, 41(1/2/3): 149-157.
11	Hendrickson G. Electrostatics and gas phase fluidized bed polymerization reactor wall sheeting[J]. Chemical Engineering Science, 2006, 61(4): 1041-1064.
12	Giffin A, Mehrani P. Effect of gas relative humidity on reactor wall fouling generated due to bed electrification in gas-solid fluidized beds[J]. Powder Technology, 2013, 235: 368-375.
13	Schmeal W R, Street J R. Polymerization in expanding catalyst particles[J]. AIChE Journal, 1971, 17(5): 1188-1197.
14	Singh D, Merrill R P. Molecular weight distribution of polyethylene produced by Ziegler-Natta catalysts[J]. Macromolecules, 1971, 4(5): 599-604.
15	Galvan R, Tirrell M. Molecular weight distribution predictions for heterogeneous Ziegler-Natta polymerization using a two-site model[J]. Chemical Engineering Science, 1986, 41(9): 2385-2393.
16	Nagel E J, Kirillov V A, Ray W H. Prediction of molecular weight distributions for high-density polyolefins[J]. Industrial & Engineering Chemistry Product Research and Development, 1980, 19(3): 372-379.
17	Hutchinson R A, Chen C M, Ray W H. Polymerization of olefins through heterogeneous catalysis X: Modeling of particle growth and morphology[J]. Journal of Applied Polymer Science, 1992, 44(8): 1389-1414.
18	Sheikhzadeh M, Pourmahdian S. A multipore model for heterogeneous catalytic polymerization: structure-performance relationships[J]. Macromolecular Reaction Engineering, 2021: 2100021.
19	Niegisch W D, Crisafulli S T, Nagel T S, et al. Characterization techniques for the study of silica fragmentation in the early stages of ethylene polymerization[J]. Macromolecules, 1992, 25(15): 3910-3916.
20	Noristi L, Marchetti E, Baruzzi G, et al. Investigation on the particle growth mechanism in propylene polymerization with MgCl₂-supported Ziegler-Natta catalysts[J]. Journal of Polymer Science Part A: Polymer Chemistry, 1994, 32(16): 3047-3059.
21	Hong S C, Teranishi T, Soga K. Investigation on the polymer particle growth in ethylene polymerization with PS beads supported rac-Ph2Si(Ind)₂ZrCl₂ catalyst[J]. Polymer, 1998, 39(26): 7153-7157.
22	Jang Y J, Naundorf C, Klapper M, et al. Study of the fragmentation process of different supports for metallocenes by laser scanning confocal fluorescence microscopy (LSCFM)[J]. Macromolecular Chemistry and Physics, 2005, 206(20): 2027-2037.
23	Kittilsen P, Svendsen H F, McKenna T F. Viscoelastic model for particle fragmentation in olefin polymerization[J]. AIChE Journal, 2003, 49(6): 1495-1507.
24	Horáčková B, Grof Z, Kosek J. Dynamics of fragmentation of catalyst carriers in catalytic polymerization of olefins[J]. Chemical Engineering Science, 2007, 62(18/19/20): 5264-5270.
25	Bossers K W, Valadian R, Zanoni S, et al. Correlated X-ray ptychography and fluorescence nano-tomography on the fragmentation behavior of an individual catalyst particle during the early stages of olefin polymerization[J]. Journal of the American Chemical Society, 2020, 142(8): 3691-3695.
26	Pater J T M, Weickert G, van Swaaij W P M. Polymerization of liquid propylene with a fourth-generation Ziegler–Natta catalyst: influence of temperature, hydrogen, monomer concentration, and prepolymerization method on powder morphology[J]. Journal of Applied Polymer Science, 2003, 87(9): 1421-1435.
27	Zanoni S, Nikolopoulos N, Welle A, et al. Early-stage particle fragmentation behavior of a commercial silica-supported metallocene catalyst[J]. Catalysis Science & Technology, 2021, 11(15): 5335-5348.
28	Weist E L, Ali A H, Conner W C. Morphological study of supported chromium polymerization catalysts. 1. Activation[J]. Macromolecules, 1987, 20(3): 689-693.
29	Rönkkö H L, Korpela T, Knuuttila H, et al. Particle growth and fragmentation of solid self-supported Ziegler-Natta-type catalysts in propylene polymerization[J]. Journal of Molecular Catalysis A: Chemical, 2009, 309(1/2): 40-49.
30	Emami M, Parvazinia M, Abedini H. Gas-phase polymerization of propylene at low reaction rates: a precise look at catalyst fragmentation[J]. Iranian Polymer Journal, 2017, 26(11): 871-883.
31	Vestberg T, Denifl P, Wilén C E. Porous versus novel compact Ziegler-Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization[J]. Journal of Applied Polymer Science, 2008, 110(4): 2021-2029.
32	Lacks D J, Mohan Sankaran R. Contact electrification of insulating materials[J]. Journal of Physics D: Applied Physics, 2011, 44(45): 453001.
33	Gilbert J S, Lane S J, Sparks R S J, et al. Charge measurements on particle fallout from a volcanic plume[J]. Nature, 1991, 349(6310): 598-600.
34	Inculet I I, Peter Castle G S, Aartsen G. Generation of bipolar electric fields during industrial handling of powders[J]. Chemical Engineering Science, 2006, 61(7): 2249-2253.
35	Forward K M, Lacks D J, Sankaran R M. Charge segregation depends on particle size in triboelectrically charged granular materials[J]. Physical Review Letters, 2009, 102(2): 028001.
36	Wang F, Wang J D, Yang Y R. Distribution of electrostatic potential in a gas-solid fluidized bed and measurement of bed level[J]. Industrial & Engineering Chemistry Research, 2008, 47(23): 9517-9526.
37	Moughrabiah W O, Grace J R, Bi X T. Effects of pressure, temperature, and gas velocity on electrostatics in gas–solid fluidized beds[J]. Industrial & Engineering Chemistry Research, 2009, 48(1): 320-325.
38	Sowinski A, Mayne A, Mehrani P. Effect of fluidizing particle size on electrostatic charge generation and reactor wall fouling in gas-solid fluidized beds[J]. Chemical Engineering Science, 2012, 71: 552-563.
39	杨遥, 葛世轶, 黄正梁, 等. 一种利用静电解析聚乙烯生长形貌的系统和方法: 111822151A[P]. 20201027.
	Yang Y, Ge S Y, Huang Z L, et al. System and method for analyzing growth morphology of polyethylene by utilizing static electricity: 111822151A[P]. 20201027.
40	Maugis D. Adhesion of spheres: the JKR-DMT transition using a dugdale model[J]. Journal of Colloid and Interface Science, 1992, 150(1): 243-269.
41	Lantz M A, O'Shea S J, Welland M E, et al. Atomic-force-microscope study of contact area and friction on NbSe₂ [J]. Physical Review B, 1997, 55(16): 10776-10785.
42	Butt H J, Cappella B, Kappl M. Force measurements with the atomic force microscope: technique, interpretation and applications[J]. Surface Science Reports, 2005, 59(1/2/3/4/5/6): 1-152.
43	Affatato S, Modena E, Carmignato S, et al. The use of Raman spectroscopy in the analysis of UHMWPE uni-condylar bearing systems after run on a force and displacement control knee simulators [J]. Wear, 2013, 297(1/2): 781-790.

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