Non-isothermal crystallization kinetics of wood powder/low melting point polyamide 6 composites
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摘要: 利用LiCl改性尼龙6 (PA6),并将其与木粉熔融共混制备了木粉/低熔点PA6复合材料,通过DSC法研究了木粉/低熔点PA6复合材料的非等温结晶动力学行为。结果表明,LiCl降低了PA6的熔点、结晶温度、结晶度和结晶速率,提高了PA6的结晶活化能。木粉是良好的成核剂,能够加快PA6的结晶速率,但却降低了其结晶度。通过Mo法分析木粉/低熔点PA6复合材料的非等温结晶动力学,结果表明,与纯PA6和木粉/PA6复合材料相比,低熔点PA6的F(T)值(表征聚合物结晶快慢参数)最大,LiCl提高了PA6在单位结晶时间内达到一定结晶度时所需的冷却速率,而木粉则与之相反。
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关键词:
- 低熔点尼龙6 (PA6) /
- 木塑复合材料 /
- LiCl /
- 非等温结晶 /
- 结晶动力学
Abstract: The polyamide 6 (PA6) modified by LiCl was compounded with wood powder in the molten state to prepare wood powder/low melting point PA6 composites. The non-isothermal crystallization kinetics of the wood powder/low melting point PA6 composites was investigated via DSC. The results show that LiCl reduces the melting point, crystallization temperature, crystallinity and crystallization rate of PA6, while increases the crystallization activation energy. As a nucleating agent, the wood powder increases the crystallization rate of PA6, but decreases the crystallinity. The non-isothermal crystallization kinetics of the wood powder/low melting point PA6 composites were analyzed by Mo equation. The results show that F(T) value (the parameters of crystallization rate) of the low melting point PA6 is higher than that of pure PA6 and the wood powder/PA6 composites. LiCl increases the cooling rate required for PA6 to reach a relative crystallinity in unit time. On the contrary, wood powder reduces the cooling rate. -
表 1 木粉/低熔点尼龙6 (LPA6)复合材料的组成
Table 1. Formulation of wood powder/low melting point polyamide 6 (LPA6) composites
Sample LPA6/wt% Wood powder/wt% LPA6 100 0 W10/LPA6 90 10 W20/LPA6 80 20 W30/LPA6 70 30 表 2 纯PA6、LPA6和木粉/LPA6复合材料的非等温结晶过程参数
Table 2. Parameters of non-isothermal crystallization process of pure PA6、LPA6 and wood powder/LAP6 composites
Sample Tm/℃ To/℃ Tp/℃ t1/2/s Xc/% PA6 221.81 185.99 176.20 54 21.43 LPA6 199.27 160.80 151.85 68 13.64 W10/LPA6 198.90 164.65 156.77 59 10.57 W20/LPA6 199.08 166.60 158.96 58 10.01 W30/LPA6 198.77 163.26 155.85 53 10.43 Notes: Tm—Melting temperature; To—Initial crystallization temperature; Tp—Peak temperature of crystallization; t1/2—Half-time of crystallization; Xc—Crystallinity. 表 3 不同相对结晶度的PA6、LPA6和木粉/LPA6复合材料的非等温结晶动力学参数
Table 3. Non-isothermal crystallization kinetic parameters of PA6, LPA6 and wood powder/LPA6 composites at different relative crystallinities
Sample Xt/% α F(T) PA6 20 1.2522 4.3944 40 1.3020 7.3706 60 1.3196 10.4352 80 1.3367 13.5863 LPA6 20 1.4405 5.2024 40 1.4088 9.6672 60 1.3964 14.5512 80 1.3613 21.9180 W10/LPA6 20 1.4718 4.2924 40 1.5326 7.4268 60 1.4627 11.8222 80 1.4170 18.1761 W20/LPA6 20 1.5201 4.0973 40 1.4478 7.7232 60 1.4254 11.7598 80 1.3978 17.6076 W30/LPA6 20 1.7152 3.0953 40 1.6408 6.2431 60 1.6259 9.9632 80 1.5400 15.8380 Notes: Xt—Relative crystallinity; α—Ratio of Avrami to Ozawa’s exponent; F(T)—Cooling rate at unit crystallization. 表 4 PA6、LPA6和木粉/LPA6复合材料非等温结晶过程中的成核活性和结晶活化能
Table 4. Nucleation activity and crystallization activation energy in process of non-isothermal crystallization of PA6, LPA6 and wood powder/LPA6 composites
Sample B or B* θ ΔE/(kJ·mol−1) PA6 7927 — −138.73 LPA6 6112 0.77 −76.80 W10/LPA6 4276 0.54 −87.92 W20/LPA6 3933 0.50 −101.23 W30/LPA6 4798 0.61 −102.25 Notes: B—Constant which is in state of homogeneous nucleation; B*—Constant which is in state of heterogeneous nucleation; θ—Nucleation activity; ΔE—Crystallization activation energy -
[1] SUDAR A, RENNER K, MOCZO J, et al. Fracture resistance of hybrid PP/elastomer/wood composites[J]. Composite Structures,2016,141:146-154. doi: 10.1016/j.compstruct.2016.01.031 [2] DAI B, WANG Q, YAN W, et al. Synergistic compatibilization and reinforcement of HDPE/wood flour composites[J]. Journal of Applied Polymer Science,2016,133(8):42958. [3] LIM K M, CHING Y C, GAN S N. Effect of palm oil bio-based plasticizer on the morphological, thermal and mechanical properties of poly(vinyl chloride)[J]. Polymers,2015,7(10):2031-2043. doi: 10.3390/polym7101498 [4] MISRA M, MOHANTY A K, TUMMALA P, et al. Injection molded biocomposites from natural fibers and modified polyamide[C]//ANTEC 2004. Society of Plastics Engineering, 2004: 1603-1607. [5] WINATA H, TURNG L S, CAULFIELD D F, et al. Applications of polyamide/cellulose fiber/wollastonite composites for microcellular injection molding[C]//ANTEC 2003. Society of Plastics Engineering, 2003: 701-705. [6] PENG J, WALSH P J, SABO R C, et al. Water-assisted compounding of cellulose nanocrystals into polyamide 6 for use as a nucleating agent for microcellular foaming[J]. Polymer,2016,84:158-166. doi: 10.1016/j.polymer.2015.12.050 [7] ZADORECKI P, ABBAS K B. Cellulose-reinforced nylon-reaction injection molded composites[J]. Polymer Composites,1985,6(3):162-167. doi: 10.1002/pc.750060306 [8] LIU H, YAO F, XU Y, et al. A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/nylon-6 blends[J]. Bioresource Technology,2010,101(9):3295-3297. doi: 10.1016/j.biortech.2009.12.073 [9] XU S, FANG Y, YI S, et al. Effects of lithium chloride and chain extender on the properties of poplar wood fiber reinforced polyamide 6 composites[J]. Polymer Testing,2018,72:132-139. doi: 10.1016/j.polymertesting.2018.10.005 [10] XU S, SUN L, HE J, et al. Effects of LiCl on crystallization, thermal, and mechanical properties of polyamide 6/wood fiber composites[J]. Polymer Composites,2018,39(s3):1574-1580. doi: 10.1002/pc.24507 [11] 赵鲲鹏, 巴子钰, 张庆法, 等. 新型木塑3D打印材料聚乳酸/木粉复合材料的非等温结晶动力学[J]. 塑料科技, 2017, 45(12):76-80.ZHAO Kunpeng, BA Ziyu, ZHANG Qingfa, et al. Non-isothermal crystallization kinetics of PLA/wood powder composites as new wood plastic 3D printing material[J]. Plastic Science and Technology,2017,45(12):76-80(in Chinese). [12] 苏宇. 竹粉/云母/聚丙烯复合材料的制备及其性能研究[D]. 大庆: 东北石油大学, 2018.SU Yu. Preparation and properties of bamboo/mica/polypropylene composites[D]. Daqing: Northeast Petroleum University, 2018(in Chinese). [13] 郑净植, 周兴平, 解孝林. SiO2-聚合物杂化微球改性聚丙烯的非等温结晶动力学[J]. 复合材料学报, 2013, 30(2):18-23.ZHENG Jingzhi, ZHOU Xingping, JIE Xiaolin. Non-isothermal crystallization kinetics of polypropylene containing silica hybrid particles as fillers[J]. Acta Materiae Compositae Sinica,2013,30(2):18-23(in Chinese). [14] GEORGE Z P, DIMITRIS S A, DIMITRIS N B, et al. Crystallization kinetics and nucleation activity of filler in polypropylene/surface-treated SiO2 nanocomposites[J]. Thermochimica Acta,2005,427(1-2):117-128. [15] 莫志深. 一种研究聚合物非等温结晶动力学的方法[J]. 高分子学报, 2008(7):656-661.MO Zhishen. A method of studying the non-isothermal crystallization kinetics of polymers[J]. Acta Polymerica Sinica,2008(7):656-661(in Chinese). [16] 裴明远, 朱廷, 张兴祥. 热定形对尼龙6-多壁碳纳米管共混纤维的影响[J]. 合成纤维, 2014, 43(7):12-16.PEI Mingyuan, ZHU Ting, ZHANG Xingxiang. Effect of heat setting on the blending fiber of PA6/MWCNTs[J]. Synthetic Fiber in China,2014,43(7):12-16(in Chinese). [17] AMINTOWLIEH Y, SARDASHTI A, SIMON LC. Polyamide 6-wheat straw composites: Degradation kinetics[J]. Polymer Composites,2012,33(6):985-989. doi: 10.1002/pc.22229 [18] AMINTOWLIEH Y, SARDASHTI A, SIMON LC. Polyamide 6–wheat straw composites: effects of additives on physical and mechanical properties of the composite[J]. Polymer Composites,2012,33(6):976-984. doi: 10.1002/pc.22228 [19] 陈彦, 徐懋, 李育英, 等. 成核剂和促进剂对聚对苯二甲酸乙二酯结晶的影响[J]. 高分子学报, 1999(1):7-14.CHEN Yan, XU Mao, LI Yuying, et al. Effects of nucleating agent and nucleation promoter on the crystallization of polyethylene terephthalate[J]. Acta Polymerica Sinica,1999(1):7-14(in Chinese). [20] WANG W, WANG D M, HE J, et al. Effect of copolymerization on crystallization kinetics of semicrystalline polyimides[J]. Journal of Applied Polymer Science,2013,127(6):4601-4609. doi: 10.1002/app.37925 [21] 孙晓婷. 等温结晶对木纤维/聚乳酸复合材料结晶与性能的影响[D]. 北京: 中国林业科学研究院, 2016.SUN Xiaoting. Effects of isothermal crystallization on crystallization and properties of wood fiber/polylactic acid composites[D]. Beijing: Chinese Academy of Forestry, 2016(in Chinese). [22] RINAWA K, MAITI S N, SONNIER R, et al. Non-isothermal crystallization kinetics and thermal behaviour of PA12/SEBS-g-MA blends[J]. Bulletin of Materials Science,2015,38(5):1315-1327. doi: 10.1007/s12034-015-1016-7