接枝细菌纤维素改性聚乳酸复合材料的制备与性能

陈倩; 曾威; 石伊康; 吴星宇; 王钊智

doi:10.13801/j.cnki.fhclxb.20220419.007

接枝细菌纤维素改性聚乳酸复合材料的制备与性能

doi: 10.13801/j.cnki.fhclxb.20220419.007

天津科技大学　化工与材料学院，天津 300457

基金项目: 国家自然科学基金(51102179)

详细信息

通讯作者:
曾威，博士，副研究员，硕士生导师，研究方向为有机/无机杂化体系的制备与应用　 E-mail: zwei@tust.edu.cn

中图分类号: TB332
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出版历程
- 收稿日期: 2022-02-21
- 修回日期: 2022-03-27
- 录用日期: 2022-04-10
- 网络出版日期: 2022-04-20
- 刊出日期: 2023-03-15

Preparation and properties of polylactic acid composite modified by bacterial cellulose

School of Chemical Engineering and Materials, Tianjin University of Science and Technology, Tianjin 300457, China

Funds: National Natural Science Foundation of China (51102179)

摘要

摘要: 聚乳酸(PLA)作为新型的绿色友好材料有非常广阔的应用前景。为有效解决PLA韧性差、结晶速率低等问题，本文提出了以纤维素改性PLA的方法。首先以细菌纤维素(BC)为底物，使L-丙交酯(LLA)在其表面进行原位开环聚合，得到了BC-g-PLA接枝产物；然后将该接枝产物作为增韧剂添加到PLA中，采用溶液浇筑的方法制备得到复合薄膜材料。结果表明：溶液接枝法的反应效率比熔融接枝法更高，接枝率可达到76.60%；通过FTIR、核磁共振波谱仪与XRD对接枝产物进行结构测试，证实了PLA成功接枝到BC表面；通过偏光显微镜观察复合薄膜材料晶体形貌发现BC-g-PLA作为异相成核剂，添加量为0.6%时，对球晶的均匀细化程度最高；通过力学性能测试发现，PLA薄膜增韧改性后断裂伸长率可提高175%，拉伸强度可提高22.7%；通过差示扫描量热仪测试复合薄膜材料的结晶性能，结晶度从未改性的2.53%提高到13.26%，结晶速率也有所增加。
- 细菌纤维素 /
- 聚乳酸 /
- 接枝 /
- 改性 /
- 力学性能 /
- 球晶形貌
Abstract: Polylactic acid (PLA) is a new green friendly material and has very promising applications. In this work, for effectively resolving the problems of poor toughness and low crystallization rate of PLA, a method of modifying PLA with cellulose was proposed. First, the BC-g-PLA grafting product was obtained by in situ ring opening of L-propyl cross-ester (LLA) using bacterial cellulose (BC) as the substrate, and then the grafting product was added to PLA as a toughening agent, and the composite film material was prepared by the solution casting method. The results show that the reaction efficiency of the solution grafting method is higher than that of the melt grafting method, and the grafting rate can reach 76.60%. Structural testing of the grafted products by FTIR, nuclear magnetic resonance spectrometer and XRD reveal that PLA is successfully grafted onto the BC surface. Polarizing microscopy observed that the spheres have the highest degree of homogeneous refinement when the loading of BC-g-PLA filler as a heterogeneous nucleating agent is 0.6%. It is found through mechanical property tests that the elongation at the break of PLA film can be increased by 175% and tensile strength by 22.7% after toughening and modification. The crystalline properties of the composite film material were tested by differential scanning calorimetry. The crystallinity increases from 2.53% unmodified to 13.26%, and the crystallization rate also increases.
- bacterial cellulose /
- polylactide /
- grafting /
- modification /
- mechanical properties /
- spherulite morphology

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图 1 细菌纤维素(BC)接枝聚乳酸(PLA)反应机制

Figure 1. Mechanism diagram of bacterial cellulose (BC) grafting polylactic acid (PLA)

Sn(Oct)₂—Stannous octoate; DMSO—Dimethyl sulfoxide

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图 2 接枝前后PLA和BC的FTIR图谱

Figure 2. FTIR spectra of PLA and BC before and after grafting

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图 3 接枝前后PLA和BC的NMR图谱

Figure 3. NMR spectra of PLA and BC before and after grafting

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图 4 接枝前后PLA和BC的XRD图谱

Figure 4. XRD patterns of PLA and BC before and after grafting

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图 5 接枝前后BC的形貌

Figure 5. Morphologies of BC before and after grafting

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图 6 BC-g-PLA-2/PLA复合薄膜材料的POM图像

Figure 6. POM images of BC-g-PLA-2/PLA composite film material

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图 7 BC含量对PLA断裂伸长率的影响

Figure 7. Effect of BC content on elongation at break of PLA

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图 8 BC含量对PLA拉伸强度的影响

Figure 8. Effect of BC content on tensile strength of PLA

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图 9 不同BC-g-PLA-2含量的复合薄膜材料BC-g-PLA-2/PLA的DSC曲线：(a) 二次升温；(b) 降温

Figure 9. DSC curves of BC-g-PLA-2/PLA composite film material with different contents of BC-g-PLA-2: (a) Secondary heating process; (b) Cooling process

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表 1 L-丙交酯(LLA)在BC中原位聚合接枝率

Table 1. Graft ratio of L-propyl cross-ester (LLA) in-situ polymerization in BC

Sample	Grafting rate/%
BC-g-PLA-1	30.90
BC-g-PLA-2	76.60

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表 2 BC-g-PLA-2/PLA复合材料DSC特征参数

Table 2. DSC characteristic parameter of BC-g-PLA-2/PLA composite

Contents of BC-g-PLA-2	T_g/℃	T_m/℃	H_m/(J·g⁻¹)	X_c/%
Neat PLA	58.2	168.1	33.33	2.53
0.2%	59.0	167.1	27.94	2.41
0.4%	59.3	167.5	25.72	5.22
0.6%	59.5	167.8	26.56	7.48
0.8%	59.6	167.0	23.42	8.38
1.0%	59.6	168.6	25.54	8.97
1.5%	59.6	167.5	35.49	11.57
2.0%	60.2	168.0	37.16	13.26
Notes: T_g—Glass transition temperature; T_m—Melting temperature; H_m—Molten Han; X_c—Crystallinity.

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