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Volume 43 Issue 11
Oct.  2019
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Structure and properties of HDPE/starch composites for fishing

  • The high density polyethylene (HDPE)/starch composites were prepared by melt blending. The effects of starch contents on the rheological properties, structure, thermal properties, mechanical properties and dynamic mechanical properties of HDPE/starch composites were studied. The results showed that the introduction of starch improved the rheology and toughness of the composites. When the content of starch was 20 wt%, it was uniformly dispersed at micron -scale thickness in HDPE/ starch composites. When the content of starch increased to 30 wt% and 50 wt%, the starch exhibited spherical dispersed phase in HDPE/starch composites, and the average diameter of starch increased from 0.6 μm to 0.8 μm. The breaking strength and breaking elongation of HDPE/ starch blends decreased significantly with the increase of starch content. All the blends with different starch contents were detected to three transition peaks. The γ transition of HDPE at low temperature corresponds to the glass transition peak of polyethylene, it was related to the movement of the amorphous chain segment, and the content of starch had little effect on the γ transition. The β transition was related to starch phase, there was no β transition for pure HDPE, and the peak became wider with the increase of starch content. The α transition in high temperature zone was related to the movement of the restricted chain near the crystallization zone of polyethylene, and it was a complex multiple relaxation process. Introducing a certain content of starch can effectively enhance the rheology and toughness of the composites, and this result can provide a theoretical and technical basis for the high- performance fishing materials based on degradable starch.
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  • [1] Chen L, Ni Y S, Bian X C, et al. A novel approach to grafting polymerization of ε-caprolactone onto starch granules[J]. Carbohydrate Polymers, 2005, 60(1): 103-109. doi: 10.1016/j.carbpol.2004.11.028
    [2] Averous L, Moro L, Dole P, et al. Properties of thermoplastic blends: starch-polycaprolactone[J]. Polymer, 2000, 41(11): 4157-4167. doi: 10.1016/s0032-3861(99)00636-9
    [3] Zerroukhi A, Jeanmaire T, Raveyre C, et al. Synthesis and characterization of hydrophobically modified starch by ring opening polymerization using imidazole as catalyst[J]. Starch, 2012, 64(8): 613-620. doi: 10.1002/star.201100154
    [4] Correa A C, Carmona V B, Simão J A, et al. Biodegradable blends of urea plasticized thermoplastic starch (UTPS) and poly(ε-caprolactone) (PCL): morphological, rheological, thermal and mechanical properties[J]. Carbohydrate Polymers, 2017, 167: 177-184. doi: 10.1016/j.carbpol.2017.03.051
    [5] Avérous L. Biodegradable multiphase systems based on plasticized starch: a review[J]. Journal of Macromolecular Science, Part C, 2004, 44(3): 231-274. doi: 10.1081/MC-200029326
    [6] van der Maarel M J E C, van der Veen B, Uitdehaag J C M, et al. Properties and applications of starch-converting enzymes of the α-amylase family[J]. Journal of Biotechnology, 2002, 94(2): 137-155. doi: 10.1016/S0168-1656(01)00407-2
    [7] Arboleda G A, Montilla C E, Villada H S, et al. Obtaining a flexible film elaborated from cassava thermoplastic starch and polylactic acid[J]. International Journal of Polymer Science, 2015: 627268. doi: 10.1155/2015/627268
    [8] Forssell P M, Mikkilä J M, Moates G K, et al. Phase and glass transition behaviour of concentrated barley starch-glycerol-water mixtures, a model for thermoplastic starch[J]. Carbohydrate Polymers, 1997, 34(4): 275-282. doi: 10.1016/S0144-8617(97)00133-1
    [9] Li M C, Lee J K, Cho U R. Synthesis, characterization, and enzymatic degradation of starch‐grafted poly (methyl methacrylate) copolymer films[J]. Journal of Applied Polymer Science, 2012, 125(1): 405-414. doi: 10.1002/app.35620
    [10] Aranda-García F J, González-Núñez R, Jasso-Gastinel C F, et al. Water absorption and thermomechanical characterization of extruded starch/poly(lactic acid)/agave bagasse fiber bioplastic composites[J]. International Journal of Polymer Science, 2015: 343294. doi: 10.1155/2015/343294
    [11] Ačkar Đ, Babić J, Jozinović A, et al. Starch modification by organic acids and their derivatives: a review[J]. Molecules, 2015, 20(10): 19554-19570. doi: 10.3390/molecules201019554
    [12] 崔永生, 王训遒, 宁卓远. 淀粉基生物降解塑料制备研究进展[J]. 中国塑料, 2014, 28(8): 1-6.Cui Y S, Wang X Q, Ning Z Y. Progress in preparation of starch-based biodegradable plastics[J]. China Plastics, 2014, 28(8): 1-6(in Chinese).
    [13] 翁云宣, 王垒, 吴丽珍, 等. 国内淀粉基塑料现状[J]. 生物产业技术, 2012(3): 17-21. doi: 10.3969/j.issn.1674-0319.2012.03.003Weng Y X, Wang L, Wu L Z, et al. Present situation of starch based plastics in China[J]. Biotechnology & Business, 2012(3): 17-21(in Chinese). doi: 10.3969/j.issn.1674-0319.2012.03.003
    [14] 陈文婷, 李俊成, 赵西坡, 等. PLA/淀粉增容增塑的研究进展[J]. 塑料, 2018, 47(2): 84-88, 92.Chen W T, Li J C, Zhao X P, et al. Recent development in compatibilization and palsticization of PLA/starch blends[J]. Plastics, 2018, 47(2): 84-88, 92(in Chinese).
    [15] 汤化伟, 夏华, 叶龚兰. 聚己内酯改性聚乳酸/淀粉共混材料的性能研究[J]. 化工新型材料, 2009, 37(6): 83-86. doi: 10.3969/j.issn.1006-3536.2009.06.030Tang H W, Xia H, Ye G L. Study on the property of polycaprolactone modified polylactic acid/starch blends[J]. New Chemical Materials, 2009, 37(6): 83-86(in Chinese). doi: 10.3969/j.issn.1006-3536.2009.06.030
    [16] 高俊, 邹琴, 吴鹏伟, 等. 氯化镁/甘油改性淀粉/聚丁二酸丁二醇酯共混材料的结构与性能[J]. 高分子材料科学与工程, 2018, 34(7): 48-53.Gao J, Zou Q, Wu P W, et al. Structure and properties of starch/poly(butylene succinate) blends plasticized with magnnesium chloride and glycerol[J]. Polymer Materials Science and Engineering, 2018, 34(7): 48-53(in Chinese).
    [17] 石孟可, 雷蓓, 罗辉, 等. 氯化镁/甘油改性羧甲基淀粉/聚乙烯醇共混材料的结构与性能[J]. 高分子材料科学与工程, 2017, 33(5): 61-65.Shi M K, Lei B, Luo H, et al. Structure and properties of carboxymethyl starch/poly(vinyl alcohol) films modified with magnnesium chloride and glycerol[J]. Polymer Materials Science and Engineering, 2017, 33(5): 61-65(in Chinese).
    [18] 刘延昌, 汪济奎, 郭卫红. 淀粉/聚乳酸共混体系的性能研究[J]. 塑料工业, 2014, 42(7): 65-67, 80. doi: 10.3969/j.issn.1005-5770.2014.07.017Liu Y C, Wang J K, Guo W H. Characteristics study of starch/PLA blends[J]. China Plastics Industry, 2014, 42(7): 65-67, 80(in Chinese). doi: 10.3969/j.issn.1005-5770.2014.07.017
    [19] 苏健裕, 陈玲, 杨连生, 等. 聚己内酯/淀粉共混材料的非等温结晶动力学[J]. 华南理工大学学报(自然科学版), 2008, 36(11): 79-84. doi: 10.3321/j.issn:1000-565X.2008.11.015Su J Y, Chen L, Yang L S, et al. Nonisothermal crystallization kinetics of polycaprolactone/starch blends[J]. Journal of South China University of Technology (Natural Science Edition), 2008, 36(11): 79-84(in Chinese). doi: 10.3321/j.issn:1000-565X.2008.11.015
    [20] 阙盼. 高密度聚乙烯的交联及结晶行为研究[D]. 长春: 长春工业大学, 2012.Que P. The study on cross-linking behavior and crystallization behavior of high-density polyethylene[D]. Changchun: Changchun University of Technology, 2012(in Chinese).
    [21] 张冬初. 高密度聚乙烯改性材料的断裂行为研究[D]. 湘潭: 湘潭大学, 2012.Zhang D C. The fracture behavior investigation of high density polyethylene modified materials[D]. Xiangtan: Xiangtan University, 2012(in Chinese).
    [22] Sailaja R R N, Chanda M. Use of maleic anhydride-grafted polyethylene as compatibilizer for HDPE-tapioca starch blends: effects on mechanical properties[J]. Journal of Applied Polymer Science, 2001, 80(6): 863-872. doi: 10.1002/1097-4628(20010509)80:6<863::aid-app1164>3.0.co;2-r
    [23] Taguet A, Bureau M N, Huneault M A, et al. Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends[J]. Carbohydrate Polymers, 2014, 114: 222-229. doi: 10.1016/j.carbpol.2014.07.073
    [24] Wahab M K A, Ismail H, Othman N. Compatibilization effects of PE-g-MA on mechanical, thermal and swelling properties of high density polyethylene/natural rubber/thermoplastic tapioca starch blends[J]. Polymer-Plastics Technology and Engineering, 2012, 51(3): 298-303. doi: 10.1080/03602559.2011.639331
    [25] Peacock A J. Handbook of Polyethylene[M]: New York: Marcel Dekker, 2000.
    [26] 徐钰珍, 方征平, 朱彦, 等. 高密度聚乙烯与丙烯酸的熔融接枝研究[J]. 中国塑料, 2004, 18(2): 26-30. doi: 10.3321/j.issn:1001-9278.2004.02.006Xu Y Z, Fang Z P, Zhu Y, et al. Melt grafting of high density polyethylene with acrylic acid[J]. China Plastics, 2004, 18(2): 26-30(in Chinese). doi: 10.3321/j.issn:1001-9278.2004.02.006
    [27] Sirotkin R O, Brooks N W. The dynamic mechanical relaxation behaviour of polyethylene copolymers cast from solution[J]. Polymer, 2001, 42(24): 9801-9808. doi: 10.1016/s0032-3861(01)00535-3
    [28] Alberola N, Cavaille J Y, Perez J. Mechanical γ and β relaxations in polyethylene-I. Glass transitions of polyethylene[J]. European Polymer Journal, 1992, 28(8): 935-948. doi: 10.1016/0014-3057(92)90322-S
    [29] Pegoretti A, Ashkar M, Migliaresi C, et al. Relaxation processes in polyethylene fibre-reinforced polyethylene composites[J]. Composites Science and Technology, 2000, 60(8): 1181-1189. doi: 10.1016/s0266-3538(00)00024-5
    [30] Khanna Y P, Turi E A, Taylor T J, et al. Dynamic mechanical relaxations in polyethylene[J]. Macromolecules, 1985, 18(6): 1302-1309. doi: 10.1021/ma00148a045.SHIJiangao
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Structure and properties of HDPE/starch composites for fishing

    Corresponding author: Min ZHANG, mzhang@shou.edu.cn
    Corresponding author: Jiangao SHI, jiangaoshi666@163.com
  • 1. College of Marine Sciences, Shanghai Ocean University, Shanghai    201306, China
  • 2. East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai    200090, China

Abstract: The high density polyethylene (HDPE)/starch composites were prepared by melt blending. The effects of starch contents on the rheological properties, structure, thermal properties, mechanical properties and dynamic mechanical properties of HDPE/starch composites were studied. The results showed that the introduction of starch improved the rheology and toughness of the composites. When the content of starch was 20 wt%, it was uniformly dispersed at micron -scale thickness in HDPE/ starch composites. When the content of starch increased to 30 wt% and 50 wt%, the starch exhibited spherical dispersed phase in HDPE/starch composites, and the average diameter of starch increased from 0.6 μm to 0.8 μm. The breaking strength and breaking elongation of HDPE/ starch blends decreased significantly with the increase of starch content. All the blends with different starch contents were detected to three transition peaks. The γ transition of HDPE at low temperature corresponds to the glass transition peak of polyethylene, it was related to the movement of the amorphous chain segment, and the content of starch had little effect on the γ transition. The β transition was related to starch phase, there was no β transition for pure HDPE, and the peak became wider with the increase of starch content. The α transition in high temperature zone was related to the movement of the restricted chain near the crystallization zone of polyethylene, and it was a complex multiple relaxation process. Introducing a certain content of starch can effectively enhance the rheology and toughness of the composites, and this result can provide a theoretical and technical basis for the high- performance fishing materials based on degradable starch.

  • 作为解决传统聚合物造成的环境污染和实现可持续发展的有效途径之一,可生物降解高分子材料的研制与使用得到了国内外的热切关注[1-4]。随着人们环保意识的提高,不可降解渔具造成的“白色污染”和“幽灵捕捞”问题受到了人们的广泛关注。为了保护海洋生态环境,避免遗弃的废旧渔具对海洋生物的危害,开发环保、可降解渔用材料已经成为我国渔业可持续发展的有效途径之一。淀粉是一种多糖类化合物,广泛存在玉米(Zea mays)、小麦(Triticum aestivum)、马铃薯(Solanum tuberosum)等植物中,具有来源广、成本低等优点,可完全生物降解为二氧化碳和水,被认为是环保的天然可再生材料[5-10]。然而,以天然淀粉为原料的生物降解材料的强度、模量等力学性能以及耐水性总是较合成塑料的差,难以单独作为一种高分子材料使用。因此,通常需要对淀粉进行热塑性改性后再与其他高分子聚合物进行共混加工制备[11-13]。淀粉常与聚乙烯、聚乙烯醇、脂肪族聚酯、聚乳酸、聚己内酯等高聚物共混,制备功能性材料[14-17]。刘延昌等[18]采用甘油作增塑剂,以原淀粉(NS)及交联淀粉(CS)为原材料分别制备了热塑性淀粉(TPS)与热塑性的交联淀粉(TPCS),将NS、TPS、TPCS分别与聚乳酸(PLA)进行共混,制备了PLA/NS、PLA/TPS及PLA/TPCS 3种共混物并对三者进行了表征。结果表明,TPCS、TPS对PLA具有增塑效果且TPCS增塑程度更高,而NS则起不到增塑PLA的作用。苏健裕等[19]采用共混挤出技术,制备不同含量的聚己内酯与淀粉的共混产物(SPCL)并对其性能进行研究。结果发现,随着淀粉含量的增加,SPCL的结晶程度降低;淀粉在SPCL中起到了成核剂的作用,加快了聚己内酯的结晶速率,但对聚己内酯的结晶程度起抑制作用。

    高密度聚乙烯(HDPE)是一种由乙烯与少量α-烯烃单体共聚生成的高结晶非极性合成树脂[20-21],在较低压力下合成,故又称低压聚乙烯。其分子结构主要为线型结构,分子中支链少、结晶度高、密度大,具有良好的耐热性和耐寒性,化学稳定性好,还具有较高的刚性和韧性,机械强度好,且价格低廉,可采用注射、挤出、吹塑和旋转成型等方法成型塑料制品,应用广泛。Sailaja等[22]以马来酸酐作为增容剂,将经甘油塑化过和未塑化的木薯淀粉与HDPE共混并测定其性能,结果发现,以马来酸酐作为增容剂,含甘油塑化淀粉的复合物比未塑化淀粉的复合物有更好的机械能。Taguet等[23]研究了含有80%HDPE和20% TPS的复合物的性能,研究表明,HDPE/TPS混合物表现出高抗裂性。Wahab等[24]研究了聚乙烯接枝马来酸酐对HDPE/天然橡胶(NR)/热塑性木薯淀粉(TPS)共混体热性能的影响,发现共混体系结晶度降低。

    本实验以HDPE和塑化木薯淀粉为原料,采用熔融共混法制备HDPE/淀粉复合材料,通过转矩流变仪研究HDPE/淀粉复合材料的流变性;通过扫描电镜(SEM)观察HDPE/淀粉复合材料的微观结构形态;采用差示扫描量热仪(differential scanning calorimetry,DSC)测试研究HDPE/淀粉复合材料的热性能;通过万能测试机测试HDPE/淀粉复合材料的力学性能;利用动态力学分析仪(dynamic thermomechanical analysis,DMA)研究HDPE/淀粉复合材料的动态力学性能,为制备可降解、性能优良的淀粉基渔用材料提供参考。

    • 塑化木薯淀粉购自张家口玉晶淀粉厂,HDPE(5000S)购自中国石化扬子石油化工有限公司。

    • 将HDPE和淀粉按实验配方(表1)加入转矩流变仪(XSS-300,上海科创橡塑机械设备有限公司)中进行熔融共混,转速60 r/min,温度180 °C,混合6 min,制得不同淀粉含量(w淀粉)的HDPE/淀粉复合材料。

      淀粉含量(w淀粉) starch weight
      0 wt% 20 wt% 30 wt% 50 wt% 100 wt%
      HDPE/淀粉
      HDPE/starch
      100/0 80/20 70/30 50/50 0/100

      Table 1.  Proportion of HDPE/ starch composites

      将制得的复合材料经DHS实验注塑机(ZSJ-5-C,苏州明辉塑胶机械有限公司)注塑制成标准样片。

    • S4800场发射扫描电镜冷场(SEM2,S4800,日本),样片经液氮淬断,断面表面喷金,导电胶固定。

      差示扫描量热仪(DSC,Netzsch 204F1,德国),HDPE/淀粉复合材料的热性能分析采用DSC仪器测试,氮气保护。试样从常温(25 °C)升温至180 °C,升温速率均为10 °C/min,氮气流量为50 mL/min。

      结晶度(XC)计算公式:

      式中,$ {\Delta H_f^{obs}}$为实测熔融焓,$ {\Delta H_f^0}$为100%完全结晶的聚合物熔融热焓。聚乙烯的$ {\Delta H_f^0}$为293 J/g[25]

      动态力学分析仪(DMA,Netzsch 242C型,德国),双悬臂模式,采用频率为1 Hz,以3 °C/min的升温速率从−184 °C升至160 °C,测定复合材料动态模量及损耗随温度的变化。

      INSTRON-4466型万能试验机(Instron 4466型,美国),采用拉伸模式。根据GB/T 1040-2006标准测试复合材料断裂强度和断裂伸长率(夹距为100 mm,拉伸速度为50 mm/min)。

    2.   结果
    • HDPE/淀粉复合材料的流变性能由哈克转矩流变仪表征,将一定比例混合的HDPE/淀粉材料加入混炼室,自由旋转的转子受到来自固体粒子的阻力,转矩急剧上升;当材料开始熔融,转矩随之下降,材料完全熔融后成为易于流动的流体,转矩达到稳态。纯HDPE和HDPE/淀粉复合材料在塑化阶段均只有一个扭矩峰,然后扭矩迅速下降达到平衡。纯HDPE最大扭矩约为60 Nm,平衡态扭矩约为15 Nm。当HDPE/淀粉比例为50/50时,最大扭矩约为13 Nm,平衡态扭矩约为6 Nm。随着w淀粉的增加,HDPE/淀粉复合材料的熔融时间缩短,转矩值降低,黏度降低,流动性增加(图1)。

      Figure 1.  Torque and time relationship of HDPE/ starch composites

    • 通过扫描电镜观察HDPE/淀粉复合材料截面的微观形态结构(图2)。纯HDPE片材耐环境应力开裂性较差,断面不齐,呈纤维状(图2-a)。HDPE/淀粉复合材料的断面较平整,这归因于淀粉的引入对复合材料韧性的改善。w淀粉为20 wt%时,在复合材料中分散均匀,随w淀粉增加,淀粉形成球状聚集体(图2-b)。w淀粉为30 wt%的复合材料中淀粉平均粒径为0.6 μm(图2-c),w淀粉为50 wt%时增大到0.8 μm(图2-d),形成“海—岛”相分离结构。

      Figure 2.  Transmission electron microscopy for HDPE/starch composites

    • 采用DSC对HDPE/淀粉复合材料进行热性能分析,通过HDPE/淀粉复合材料的DSC分析曲线(图3),根据熔融峰面积计算得到复合材料中HDPE的结晶度(图4)。与纯HDPE相比,HDPE/淀粉复合材料中HDPE的熔融温度(Tm)向低温方向移动,结晶度下降,结晶熔融峰变窄。纯HDPE结晶度为53.58%,当w淀粉为50 wt%时,HDPE/淀粉复合材料结晶度为24.19%,与纯HDPE相比下降54.85%。

      Figure 4.  Degree of crystallinity for HDPE/ starch composites

      Figure 3.  DSC analysis curves of HDPE/ starch composites

    • 利用DMA研究了HDPE/淀粉复合材料的动态力学性能,得到了不同w淀粉的HDPE/淀粉复合材料在−184 °C~160 °C温度区间的储能模量(E′)和损耗因子(tanδ)变化曲线(图5)。HDPE/淀粉复合材料的E′与纯HDPE相比均降低。当温度为30 °C时,纯HDPE的模量为0.65 GPa,当w淀粉为20 wt%的HDPE/淀粉复合材料模量为0.48 GPa,下降了26%(图5-a)。在宽的测试温度范围内,不同w淀粉的HDPE/淀粉复合材料均被检测到3个转变峰(图5-b),γ转变峰对应为聚乙烯的玻璃化转变峰,淀粉含量对γ转变峰影响不大。纯HDPE不存在β峰,因此β转变与淀粉分散相有关,且随w淀粉增加β峰变宽。α转变与聚乙烯结晶区附近受限链段的运动有关,是一个复杂的多重松弛过程。

      Figure 5.  HDPE/ starch composites E′(a) and tan δ (b) vs. temperature

    • 采用万能测试机测试了HDPE/淀粉复合材料的力学性能,引入淀粉后复合材料的断裂强力和断裂伸长率均显著下降(图6)。与纯HDPE相比,淀粉材料的断裂强力和断裂伸长率分别降低85.28%和93.08%;w淀粉为20 wt%的HDPE/淀粉复合材料的断裂强力和断裂伸长率分别降低了52.87%和92.57%;w淀粉为50 wt%的HDPE/淀粉复合材料的断裂强力和断裂伸长率分别降低了58.39%和97.05%(表2)。

      Figure 6.  Mechanical tensile properties of HDPE/ starch composites

      W淀粉/wt%
      starch weight
      断裂强力/MPa
      breaking strength
      断裂伸长率/%
      elongation at break
      0 43.5 781
      20 20.5 58
      30 22.1 24
      50 18.1 23
      100 6.4 54

      Table 2.  Mechanical tensile properties of HDPE/ starch composites

    3.   讨论
    • 从流变性能分析,纯HDPE和HDPE/淀粉复合材料在塑化阶段均只有一个扭矩峰,纯HDPE最大扭矩约为60 Nm,然后扭矩迅速下降达到平衡态,平衡态扭矩约为15 Nm,与徐钰珍等[26]的研究结果一致。w淀粉为50 wt%时,最大扭矩约为13 Nm,平衡态扭矩约为6 Nm。经淀粉改性后的复合材料转矩显著降低,熔融时间缩短,说明淀粉的引入有效改善了复合材料的加工流变性。

      从微观结构分析,与纯HDPE相比,HDPE/淀粉复合材料断面较整齐,这是由于淀粉的引入对复合材料韧性的改善。淀粉在HDPE基体中呈微米级分布,w淀粉为20 wt%的复合材料中淀粉均匀分布,w淀粉为30 wt%和50 wt%的复合材料中淀粉形成球状聚集体,形成“海—岛”相分离结构,其平均粒径从0.6 μm增加到0.8 μm。这种“海—岛”相分离结构是在熔融共混过程中形成的,说明熔融加工条件下HDPE与淀粉在加工温度范围内并非完全相容。

      在DSC热分析结果中可以明显看出,随w淀粉增加,HDPE/淀粉复合材料的Tm向低温方向移动,结晶度显著下降,结晶熔融峰变窄。这是由于淀粉的引入破坏了HDPE的结晶完善程度,使其有序性降低,导致复合材料总结晶度下降。随w淀粉增加,结晶度降低,一方面是因为HDPE组分减少,另一方面是由于复合材料中淀粉与HDPE大分子链间相互缠结,限制了HDPE大分子进一步嵌入晶格的运动,导致HDPE结晶度降低。这与Wahab等[24]研究的共混改性HDPE结论一致。

      与纯HDPE相比较,HDPE/淀粉复合材料的断裂强力与断裂伸长率均显著降低,主要原因是淀粉与HDPE存在相分离,淀粉颗粒分散在HDPE分子链间,削弱了分子链的相互作用,从而导致力学性能下降。由电镜扫描结果可知,w淀粉较高时,淀粉在基体中形成微米级微区,因此易形成应力集中区,导致力学性能显著降低。

      HDPE/淀粉复合材料的E′相比纯HDPE均显著降低,这说明淀粉的引入影响了复合材料的刚性,这与复合材料的总结晶度的下降有关。在宽的测试温度范围内,不同w淀粉的HDPE/淀粉复合材料均被检测到3个转变峰,大量文献表明,HDPE低温下的γ转变峰对应为聚乙烯的玻璃化转变峰[27-29],对应于非晶态链段的运动,淀粉含量对γ转变峰影响不大。纯HDPE不存在β峰,因此β转变与淀粉分散相有关,且随w淀粉增加β峰变宽。这归因于w淀粉增加,淀粉形成的球状分散相粒径逐渐增大,淀粉相链段增多。高温区(100 °C左右)出现的转变(α转变)与聚乙烯结晶区附近受限链段的运动有关[28],是一个复杂的多重松弛过程。Khanna等[30]已证明聚乙烯的α转变只与晶片表面的缠结分子、结晶缺陷有关。随w淀粉的增加,结晶度下降,晶区附近链段间减少,链段运动活化能降低,因而α转变峰温度移向低温。在该峰值区域E′急剧下降,HDPE/淀粉复合材料的刚性、机械性能显著降低。

      HDPE/淀粉复合材料是一种可生物降解淀粉基渔用新材料,其研发与产业化应用为可降解渔具材料(如蟹笼网衣、或藻类设施用绳网和深远海养殖网具等)的选配、产业化应用提供一种新的技术途径,助力我国绿色渔业战略的实施和发展。

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