Preparation and properties of poly(epoxidized palm oil)/poly(lactic acid)blends via dynamic vulcanization
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摘要: 聚乳酸(PLA)具有优异的力学性能，无毒性、可再生、可生物降解，且生物相容性好，是目前应用最广泛的生物基塑料之一。然而，PLA价格高、脆性大、韧性差等缺点严重限制了其在更多领域的应用。为克服这些缺点，采用双螺杆挤出和注塑成型技术制备生物基的聚环氧棕榈油(PEPO)/聚乳酸(PLA)共混物以增强PLA的韧性，表征了共混物的结晶行为、流变性能、力学性能、热稳定性和微观形貌，以揭示PEPO与PLA的动态硫化机制及PEPO橡胶相对PLA的增韧机制。结果表明：环氧棕榈油(EPO)与PLA熔融共混过程中，EPO在阳离子引发剂的作用下发生自聚，进而在PLA基体中形成颗粒状PEPO橡胶相；两相结构的形成使共混物受力时发生塑性形变，导致PLA的韧性显著提升；当PEPO的用量为20wt%时，共混物的断裂伸长率和拉伸韧性分别从纯PLA的10%和4.7 MJ/m3提高至100%和30.4 MJ/m3，但其拉伸强度、拉伸模量、储存模量和玻璃化转变温度均呈现下降趋势。Abstract: Poly(lactic acid) (PLA) has the advantages of high mechanical properties, non-toxicity, renewablility, biodegradability and biocompatability. PLA has become one of the most widely used biobased plastics. However, PLA also has the disadvantages of high cost, high brittleness and low ductility, which hinders its further application in some fields. Thus, a series of bio-based poly(epoxidized palm oil) (PEPO)/PLA blends were prepared by twin-screw extrusion and injection molding techniques. The crystallization behavior, rheological properties, mechanical properties, thermal stability and micro-morphology of the blends were studied. The dynamic vulcanization mechanism of PEPO and PLA blends as well as the toughening mechanism of PEPO rubber phase in PLA were investigated. The results show that during the melt-blending of epoxidized palm oil (EPO) and PLA, EPO can self-polymerize with the help of the cationic initiator, thus forming PEPO rubber phase in PLA matrix. The formation of two-phase structure endows the blends plastic deformation under stress, leading to significant toughening efficiency on PLA. With an addition of 20wt% PEPO, the elongation at break and tensile toughness of the blend increase from 10% and 4.7 MJ/m3 (pure PLA) to 100% and 30.4 MJ/m3, respectively; but the tensile strength, tensile modulus, storage modulus and glass transition temperature of the blends decrease.
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Key words:
- epoxidized palm oil /
- poly(lactic acid) /
- dynamic vulcanization /
- bio-based blends /
- toughening
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图 3 (a) 过氧酸法合成EPO路线；(b) BF3NH2Et引发EPO的阳离子聚合
Figure 3. (a) Synthesis of EPO by peroxylation; (b) Proposed cationic polymerization of EPO initiated by BF3NH2Et
图 1 棕榈油(PO)和环氧棕榈油(EPO)的ATR-FTIR图谱
Figure 1. ATR-FTIR spectra of palm oil (PO) and epoxidized palm oil (EPO)
图 2 EPO的1H NMR (a) 和13C NMR (b) 图谱
Figure 2. 1H NMR (a) and 13C NMR (b) spectra of EPO
图 4 EPO阳离子聚合过程的DSC曲线 (a)、聚环氧棕榈油(PEPO)/聚乳酸(PLA)中PLA的GPC曲线 (b)
Figure 4. DSC curve of cationic polymerization of EPO (a) and GPC profiles ofpoly(lactic acid) (PLA) dissolved from poly(epoxidized palm oil) (PEPO)/PLA blends (b)
图 5 PEPO/PLA共混物的DSC曲线
Figure 5. DSC curves of PEPO/PLA blends
Tg—Glass transition temperature; Tcc—Cold crystallization temperature; Tm—Melting temperature
图 6 190°C时PEPO/PLA共混物的复数黏度 (a)、相角δ (b)、弹性模量和损耗模量 (c) 随频率的函数关系
Figure 6. Complex viscosity (a), phase angle δ (b), elasticity modulus and loss modulus (c) vs. frequency of PEPO/PLA blends at 190 °C
图 7 PEPO/PLA共混物的DMA曲线：(a) 储能模量；(b) 阻尼参数
Figure 7. DMA curves of PEPO/PLA blends: (a) Storage modulus; (b) Damping parameter
图 8 PEPO/PLA共混物拉伸应力-应变 (a)、弯曲强度和模量 (b)、拉伸强度和断裂伸长率 (c)、拉伸模量和拉伸韧性 (d)
Figure 8. Tensile stress-strain (a), flexural strength and modulus (b), tensile strength and fracture elongation (c) and tensile modulus and toughness of PEPO/PLA blends (d)
图 9 PLA (a)、5wt%PEPO/PLA (b)、10wt%PEPO/PLA (c)、15wt%PEPO/PLA (d)、20wt%PEPO/PLA (e)和高倍数(×20000)20wt%PEPO/PLA低温断面 (f) 的SEM图像
Figure 9. SEM images of cryo-fractured surfaces of PLA (a), 5wt%PEPO/PLA (b), 10wt%PEPO/PLA (c), 15wt%PEPO/PLA (d), 20wt%PEPO/PLA (e), and 20wt%PEPO/PLA with higher magnification (×20000) (f)
图 10 PLA (a)、5wt%PEPO/PLA (b)、10wt%PEPO/PLA (c)、15wt%PEPO/PLA (d)、20wt%PEPO/PLA (e)和高倍数(×20000)20wt%PEPO/PLA拉伸断面 (f) 的SEM图像
Figure 10. SEM images of tensile-fractured surfaces of PLA (a), 5wt%PEPO/PLA (b), 10wt%PEPO/PLA (c), 15wt%PEPO/PLA (d), 20wt%PEPO/PLA (e), and 20wt%PEPO/PLA with higher magnification (×20000) (f)
表 1 PEPO/PLA共混物的DSC分析结果
Table 1. DSC results of PEPO/PLA blends
Sample Tg/°C Tcc/°C Tm/°C ΔHcc/(J·g−1) ΔHm/(J·g−1) Xc/% Pure PLA 66.9 103.3 172.4 28.9 31.8 3.1 5wt%PEPO/PLA 66.8 99.8 171.5 25.2 35.7 11.8 10wt%PEPO/PLA 66.3 99.1 172.1 24.8 36.7 14.1 15wt%PEPO/PLA 66.2 97.0 173.4 20.3 34.7 18.2 20wt%PEPO/PLA 65.9 96.4 172.3 7.6 36.1 38.1 Notes: ΔHcc—Cold crystallization enthalpy; ΔHm—Melting of the blend; Xc—Crystallinity. 
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表 2 PEPO/PLA共混物的DMA测试结果
Table 2. DMA results of PEPO/PLA blends
Samples E′ at 25°C/GPa Tg/°C Pure PLA 2.78 68.2 5wt%PEPO/PLA 2.33 67.4 10wt%PEPO/PLA 2.21 66.7 15wt%PEPO/PLA 2.06 66.2 20wt%PEPO/PLA 1.65 65.8 Note: E′—Storage modulus.
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[1] 黎永轩, 朱韵来, 彭博, 等. 生物降解聚酯弹性体粒子改性聚乳酸复合材料的制备及性能[J]. 复合材料学报, 2020, 38(8):2536-2546.LI Yongxuan, ZHU Yunlai, PENG Bo, et al. Preparation and properties of biodegradable polyester elastomer particle modified poly(lactic acid) composites[J]. Acta Materiae Compositae Sinica,2020,38(8):2536-2546(in Chinese). [2] 黄海超, 宋国林, 唐国翌, 等. 驻极体-增塑剂复合改性聚乳酸熔喷非织造材料的制备及性能[J]. 复合材料学报, 2019, 36(3):563-571.HUANG Haichao, SONG Guolin, TANG Guoyi, et al. Preparation and characterization of poly(lactic acid) meltblown nonwovens modified by electrets and co-plasticizers[J]. Acta Materiae Compositae Sinica,2019,36(3):563-571(in Chinese). [3] WU B, ZENG Q, NIU D, et al. Design of supertoughened and heat-resistant PLLA/elastomer blends by controlling the distribution of stereocomplex crystallites and the morphology[J]. Macromolecules,2019,52(3):1092-1103. doi: 10.1021/acs.macromol.8b02262 [4] LIU H, CHEN N, SHAN P, et al. Toward fully bio-based and supertough PLA blends via in situ formation of cross-linked biopolyamide continuity network[J]. Macromolecules,2019,52(21):8415-8429. doi: 10.1021/acs.macromol.9b01398 [5] QUILES-CARRILLO L, BLANES-MARTINEZ M M, MONTANES N, et al. Reactive toughening of injection-molded polylactide pieces using maleinized hemp seed oil[J]. European Polymer Journal,2018,98:402-410. doi: 10.1016/j.eurpolymj.2017.11.039 [6] QUILES-CARRILLO L, DUART S, MONTANES N, et al. Enhancement of the mechanical and thermal properties of injection-molded polylactide parts by the addition of acrylated epoxidized soybean oil[J]. Materials and Design,2018,140:54-63. doi: 10.1016/j.matdes.2017.11.031 [7] QUILES-CARRILLO L, MONTANES N, SAMMON C, et al. Compatibilization of highly sustainable polylactide/almond shell flour composites by reactive extrusion with maleinized linseed oil[J]. Industrial Crops and Products,2018,111:878-888. doi: 10.1016/j.indcrop.2017.10.062 [8] https://www.sohu.com/a/365530288_473133. 中国棕榈油行业市场需求与投资规划分析报告 [R]. 前瞻产业研究院, 2019.https://www.sohu.com/a/365530288_473133. Analysis report on market demand and investment planning of Chinese palm oil industry [R]. Foreview Industry Research Institute, 2019 (in Chinese). [9] 马传国, 郭瑞华, 张科红. 过氧甲酸法环氧棕榈油的制备研究[J]. 中国油脂, 2009, 34(12):57-61. doi: 10.3321/j.issn:1003-7969.2009.12.015MA Chuanguo, GUO Ruihua, ZHANG Kehong. Preparation of epoxy palm oil by peroxyformic acid method[J]. China Oils and Fats,2009,34(12):57-61(in Chinese). doi: 10.3321/j.issn:1003-7969.2009.12.015 [10] TAN S, CHOW W. Thermal properties, fracture toughness and water absorption of epoxy-palm oil blends[J]. Polymer Plastics Technology and Engineering,2010,49(9):900-907. doi: 10.1080/03602551003682042 [11] ALTUNAl F I, PRTTARIN V, WILLIAMS R J. Self-healable polymer networks based on the cross-linking of epoxidised soybean oil by an aqueous citric acid solution[J]. Green Chemistry,2013,15(12):3360-3366. doi: 10.1039/c3gc41384e [12] AL-MULLA E A J, YUNUS W M Z W, IBRAHIM N A B, et al. Properties of epoxidized palm oil plasticized polytlactic acid[J]. Journal of Materials Science,2010,45(7):1942-1946. doi: 10.1007/s10853-009-4185-1 [13] VIJAYARAJAN S, SELKE S E, MATUANA L M. Continuous blending approach in the manufacture of epoxidized soybean-plasticized poly (lactic acid) sheets and films[J]. Macromolecular Materials and Engineering,2014,299(5):622-630. doi: 10.1002/mame.201300226 [14] FERRI J, GARCIA-GARCIA D, SANCHEZ-NACHER L, et al. The effect of maleinized linseed oil (MLO) on mechanical performance of poly (lactic acid)-thermoplastic starch (PLA-TPS) blends[J]. Carbohydrate Polymers,2016,147:60-68. doi: 10.1016/j.carbpol.2016.03.082 [15] CARBONELL-VERDU A, GARCIA-GARCIA D, DOMINICI F, et al. PLA films with improved flexibility properties by using maleinized cottonseed oil[J]. European Polymer Jour-nal,2017,91:248-259. doi: 10.1016/j.eurpolymj.2017.04.013 [16] FERRI J M, SAMPER M D, GARCÍA-SANOGUERA D, et al. Plasticizing effect of biobased epoxidized fatty acid esters on mechanical and thermal properties of poly (lactic acid)[J]. Journal of Materials Science,2016,51(11):5356-5366. doi: 10.1007/s10853-016-9838-2 [17] MAUCK S C, WANG S, DING W, et al. Biorenewable tough blends of polylactide and acrylated epoxidized soybean oil compatibilized by a polylactide star polymer[J]. Macromolecules,2016,49(5):1605-1615. doi: 10.1021/acs.macromol.5b02613 [18] CHEN Y, YUAN D, XU C. Dynamically vulcanized biobased polylactide/natural rubber blend material with continuous cross-linked rubber phase[J]. ACS Applied Materials and Interfaces,2014,6(6):3811-3816. doi: 10.1021/am5004766 [19] LIU W, QIU J, ZHU L, et al. Tannic acid-induced crosslinking of epoxidized soybean oil for toughening poly(lactic acid) via dynamic vulcanization[J]. Polymer,2018,148:109-118. doi: 10.1016/j.polymer.2018.06.021 [20] ZHAO T H, YUAN W Q, LI Y D, et al. Relating chemical structure to toughness via morphology control in fully sustainable sebacic acid cured epoxidized soybean oil toughened polylactide blends[J]. Macromolecules,2018,51(5):2027-2037. doi: 10.1021/acs.macromol.8b00103 [21] ZHAO T H, HE Y, LI Y D, et al. Dynamic vulcanization of castor oil in a polylactide matrix for toughening[J]. RSC Advances,2016,6(83):79542-79553. doi: 10.1039/C6RA13631A [22] ASTM. Standard test method for tensile properties of plastics: ASTM D638—2010[S]. West Conshohocken: ASTM, 2010. [23] ASTM. Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials: ASTM D790—2010[S]. West Conshohocken: ASTM, 2010. [24] ISO. Plastics—Determination of charpy impact properties—Part 1: Non-instrument impact test: ISO 179—2010[S]. Geneva: ISO, 2010. [25] WANG L, LEE R E, WANG G, et al. Use of stereocomplex crystallites for fully-biobased microcellular low density poly (lactic acid) foams for green packaging[J]. Chemical Engineering Journal,2017,327:1151-1162. doi: 10.1016/j.cej.2017.07.024 [26] CHIENG B W, IBRAHIM N A, THEN Y Y, et al. Epoxidized vegetable oils plasticized poly(lactic acid) biocomposites: Mechanical, thermal and morphology properties[J]. Molecules,2014,19(10):16024-16038. doi: 10.3390/molecules191016024 [27] CARBONELL-VERDU A, SAMPER M D, GARCÍA-GARCÍA D, et al. Plasticization effect of epoxidized cottonseed oil (ECSO) on poly(lactic acid)[J]. Industrial Crops and Products,2017,104:278-286. doi: 10.1016/j.indcrop.2017.04.050 [28] FANG H G, JIANG F, WU Q, et al. Supertough polylactide materials prepared through in situ reactive blending with PEG-based diacrylate monomer[J]. ACS Applied Materials and Interfaces,2014,6(16):13552-13563. doi: 10.1021/am502735q [29] MENG X, BOCHAROVA V, TEKINALP H, et al. Toughening of nanocelluose/PLA composites via bio-epoxy interaction: Mechanistic study[J]. Materials and Design,2018,139:188-197. doi: 10.1016/j.matdes.2017.11.012 [30] QIAN S, ZHANG H, YAO W, et al. Effects of bamboo cellulose nanowhisker content on the morphology, crystallization, mechanical, and thermal properties of PLA matrix biocomposites[J]. Composites Part B: Engineering,2018,133:203-209. doi: 10.1016/j.compositesb.2017.09.040 -
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