DCP原位增容PPCU/PLA共混物的增韧机制及性能

李景波; 谭佳; 于洪涛; 刘小超; 刘跃军; 崔玲娜

DCP原位增容PPCU/PLA共混物的增韧机制及性能

湖南工业大学　包装与材料工程学院, 株洲 412007

基金项目: 国家自然科学基金 (12372245)

详细信息

通讯作者:
刘小超，博士，副教授，硕士生导师，研究方向为高分子材料加工工程、先进包装材料与技术　E-mail: xcliu_2014@163.com

中图分类号: TB332
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- HTML全文浏览量: 16
- 被引次数: 0
出版历程
- 收稿日期: 2024-07-08
- 修回日期: 2024-09-02
- 录用日期: 2024-09-07
- 网络出版日期: 2024-09-25

In situ compatibilization of the toughening mechanism and properties in PPCU/PLA blends via DCP

School of Packaging and Material Engineering, Hunan University of Technology, Zhuzhou 412007

Funds: National Natural Science Foundation of China (12372245)

摘要

摘要: 聚乳酸(PLA)的脆性严重限制了其应用，使用弹性体共混增韧PLA是一种可行的策略，然而共混物两相相容性较差的问题仍亟待解决。本文采用过氧化二异苯丙(DCP)为反应增容剂与PLA、聚碳酸亚丙酯-热塑性聚氨酯弹性体(PPCU)熔融共混制备了PPCU/PLA共混物，研究了DCP添加量对共混物相形貌、流变性能、力学性能等的影响。结果表明：DCP引发了PLA与PPCU分子链间的支化交联反应，随着DCP添加量增加，PPCU/PLA共混物的复数黏度以及储能模量也随之增大，弹性行为逐渐增强，Cole-Cole图表明当DCP添加量大于0.3wt%后，共混物具有较高的同质性；随着DCP添加量增加，共混物相界面逐渐变得模糊，分散相尺寸明显减小，共混物相形貌得到改善。DCP的加入可显著提高共混物的断裂伸长率，添加量为0.2wt%的共混物断裂伸长率达到最大值224.37%，是未添加DCP共混物断裂伸长率的10.68倍；PPCU/PLA共混物的缺口冲击强度随着DCP添加量的增加而增大，添加量为0.5wt%的共混物其冲击强度达到了7.91 kJ/m²，是未添加DCP的共混物的2.94倍，PPCU/PLA共混物力学性能的提高主要归因于其两相相容性的改善。
- 聚乳酸 /
- 聚碳酸亚丙酯-热塑性聚氨酯弹性体 /
- 相容性 /
- 流变性能 /
- 力学性能
Abstract: The intrinsic brittleness of polylactic acid (PLA) greatly restricts broader application in multiple fields, while the blending with elastomer is considered a feasible strategy to improve the ductility of PLA materials. Unfortunately, the poor compatibility of two phases needs to be solved. In this work, using diisophenyl peroxide (DCP) as reactive compatibilizer, PLA and poly(propylene carbonate) polyurethane (PPCU) were melt blended to prepare PPCU/PLA blends. The effects of DCP content on the phase morphology, rheological properties and mechanical properties of PPCU/PLA blends were investigated. The results demonstrated that DCP initiated the branched crosslinking reaction between PLA and PPCU molecular chains. With the increase of DCP content, the complex viscosity and storage modulus of PPCU/PLA blends also enhanced, indicating the reinforcement of elastic behavior, and the Cole-Cole plot indicates that when the DCP addition exceeds 0.3wt%, the blend exhibits high homogeneity. As the DCP content increases, the phase interface of the blend gradually becomes blurred, the dispersed phase size significantly decreases, and the phase morphology of the blend is improved. Meanwhile, the addition of DCP significantly enhance the elongation at break of the blends. The elongation at break of 0.2wt% DCP in PPCU/PLA increased to 224.37%, which was 10.68 times as high as that of the blends without adding DCP. Additionally, notched impact strength of PPCU/PLA blends increases with DCP addition. When 0.5wt% DCP was added into the blends, the impact strength of the blends is increased to 7.91 kJ/m², which is more than 2.94 times than the pure PPCU/PLA blends. The proposed modification strategy may be responsible for the enhancement of mechanical properties of PPCU/PLA blends, exhibiting the improvement of compatibility between the two phases.
- poly(lactic acid) /
- poly(propylene carbonate) polyurethane /
- compatibility /
- rheological properties /
- mechanical properties

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图 1 熔融共混过程中的主要化学反应

Figure 1. Main chemical reactions in the melt blending process

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图 2 PLA、PLA-D、PPCU、PPCU-D (a) 以及各PPCU/PLA共混物 (b) 的FTIR谱图

Figure 2. FTIR spectra of PLA、PLA-D、PPCU、PPCU-D (a) and PPCU/PLA blends (b)

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图 3 PPCU/PLA共混物在熔融共混过程中的扭矩变化及其凝胶含量：(a) PPCU/PLA共混物的扭矩变化曲线；(b) PPCU/PLA共混物凝胶含量图

Figure 3. Torque change of PPCU/PLA blend during melt blending and gel content of PPCU/PLA blend: (a) Torque change curve of PPCU/PLA blend;(b) Gel Content Diagram of PPCU/PLA Blend

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图 4 PPCU/PLA共混物的动态流变曲线：(a) 复数黏度η^*；(b) 储能模量G'；(c) Han曲线；(d) Cole-Cole曲线

Figure 4. Dynamic rheological profiles of PPCU/PLA blends: (a) Complex viscosity η*; (b) Storage modulus G'; (c) Han plots; (d) Cole-Cole plots

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图 5 PPCU/PLA共混物脆断面SEM图：(a) PPCU/PLA; (b) PPCU/PLA-0.1 D; (c) PPCU/PLA-0.2 D; (d) PPCU/PLA-0.3 D; (e) PPCU/PLA-0.4 D;(f) PPCU/PLA-0.5 D

Figure 5. SEM micrographs showing cvro-fractured surface morphology of PPCU/PLA blends: (a) PPCU/PLA; (b) PPCU/PLA-0.1 D; (c) PPCU/PLA-0.2 D; (d) PPCU/PLA-0.4 D; (e) PPCU/PLA-0.4 D; (f) PPCU/PLA-0.5 D

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图 6 刻蚀后的PPCU/PLA共混物脆断面SEM图：(a') PPCU/PLA;(b') PPCU/PLA-0.1 D; (c') PPCU/PLA-0.2 D; (d') PPCU/PLA-0.3 D;(e') PPCU/PLA-0.4 D; (f ') PPCU/PLA-0.5 D

Figure 6. SEM micrographs showing cvro-fractured surface morphology of PPCU/PLA blends after etching: (a') PPCU/PLA; (b') PPCU/PLA-0.1 D; (c') PPCU/PLA-0.2 D; (d') PPCU/PLA-0.4 D; (e') PPCU/PLA-0.4 D; (f ') PPCU/PLA-0.5 D

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图 7 PPCU/PLA共混物的第二次升温DSC曲线

Figure 7. Second DSC heating curves of PPCU/PLA blends

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图 8 PPCU/PLA共混物的TGA图以及DTG图：(a) TGA图；(b) DTG图

Figure 8. TGA plots and DTG plots of PPCU/PLA blends: (a) TGA plots; (b) DTG plots

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图 9 PLA以及 PPCU/PLA共混物力学性能图：(a) 应力应变曲线；(b) 拉伸强度与断裂伸长率；(c) 缺口冲击强度

Figure 9. Mechanical properties of PLA and PPCU/PLA blends: (a) Stress-strain curve; (b) Tensile strength and elongation at break; (c) Notched impact strength

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图 10 PPCU/PLA共混物增韧机制示意图

Figure 10. Schematic diagram of the toughening mechanism in the PPCU/PLA blends

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图 11 PPCU/PLA共混物冲击断面SEM图：(a) PPCU/PLA;(b) PPCU/PLA-0.1 D;(c) PPCU/PLA-0.2 D;(d) PPCU/PLA-0.3 D;(e) PPCU/PLA-0.4 D;(f) PPCU/PLA-0.5 D

Figure 11. SEM micrographs of impact-fractured surfaces of PPCU/PLA blends: (a) PPCU/PLA;(b) PPCU/PLA-0.1 D; (c) PPCU/PLA-0.2 D;(d) PPCU/PLA-0.3 D;(e) PPCU/PLA-0.4 D;(f) PPCU/PLA-0.5 D

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表 1 PPCU/PLA共混物原料配比

Table 1. Composition of PLA/PPCU blends

Sample	PLA/wt%	PPCU/wt%	DCP/wt%
PLA	100	0	0
PPCU/PLA	75	25	0
PPCU/PLA-0.1 D	75	25	0.1
PPCU/PLA-0.2 D	75	25	0.2
PPCU/PLA-0.3 D	75	25	0.3
PPCU/PLA-0.4 D	75	25	0.4
PPCU/PLA-0.5 D	75	25	0.5
Notes：PLA—poly(lactic acid); PPCU—poly(propylene cabonate) polyurethane; The xD in the table represents the amount of diisopropyl peroxide (DCP) added, for example 0.1 D means the amount of DCP added to the blend is 0.1 wt%.

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表 2 刻蚀后脆断PPCU/PLA共混物中PPCU相以及空穴尺寸

Table 2. PPCU phase and hole size in cvro-fractured PPCU/PLA blends after etching

Sample	PPCU/PLA	PPCU/PLA-0.1 D	PPCU/PLA-0.2 D	PPCU/PLA-0.3 D	PPCU/PLA-0.4 D	PPCU/PLA-0.5 D
PPCU particle size/nm	—	178±72	161±32	175±37	111±19	106±20
Hole diameter/nm	525±159	463±69	414±140	387±114	352±154	273±55

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表 3 PPCU/PLA共混物热失重参数

Table 3. Thermal weight loss parameters of PPCU/PLA blends

Sample	T_5%/℃	T_50%/℃	T_max/℃
PLA	342.3	366.7	369.8
PPCU	269.3	325.6	339.3
PPCU/PLA	285.4	323.5	325.1
PPCU/PLA-0.1 D	294.3	324.4	325.9
PPCU/PLA-0.2 D	305.0	335.5	330.1
PPCU/PLA-0.3 D	293.0	323.5	325.4
PPCU/PLA-0.4 D	294.7	332.3	325.7
PPCU/PLA-0.5 D	284.9	320.3	319.2
Notes：T_5%, T_50% and T_max are the temperatures at which the weight loss of the sample is 5%, 50% and the weight loss rate is the highest, respectively.

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表 4 PPCU/PLA共混物力学性能

Table 4. Mechanical properties of PPCU/PLA blends

Sample	Tensile strength /MPa	Elongation at break /%	Notched impact strength /(kJ·m²)
PLA	68.61±0.74	7.06±0.63	2.25±0.18
PPCU/PLA	52.36±2.99	21.00±6.51	2.69±0.62
PPCU/PLA-0.1 D	44.84±1.32	122.12±13.53	3.20±0.60
PPCU/PLA-0.2 D	42.34±0.67	224.37±44.98	5.53±1.45
PPCU/PLA-0.3 D	43.19±1.63	173.80±20.37	6.33±0.94
PPCU/PLA-0.4 D	44.78±0.70	187.50±22.44	6.05±1.19
PPCU/PLA-0.5 D	43.78±0.57	22.69±3.82	7.91±2.19

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