【作者】 周杰；

【导师】 刘文涛； 刘浩；

【作者基本信息】 郑州大学 ， 材料科学与工程， 2025， 硕士

【摘要】 聚合物材料的广泛应用推动了现代工业的发展,但传统石油基聚合物在环境中的持久性问题日益严峻,微塑料污染已对水体和土壤生态系统构成威胁。为应对这一挑战,欧盟《一次性塑料指令》和中国“禁塑令”等政策加强了不可降解塑料的管控。生物基可降解高分子材料因其可调降解周期和低碳足迹而成为研究热点。聚丁二酸/对苯二甲酸丁二醇酯（PBST）和聚乳酸（PLA）虽为主流可降解材料,但力学性能和降解性能不足,限制了其高性能应用。近年来,生物基异山梨醇（IS）凭借刚性呋喃环结构和可再生特性,广泛用于聚酯改性,提升了力学性能、降解性和热稳定性。本文通过异山梨醇（IS）化学改性PBST,优化其力学性能与降解性,并与PLA熔融共混,采用多功能环氧聚合物（Joncryl ADR-4468）和六亚甲基二异氰酸酯（HDI）进行增容研究,旨在构建兼具高韧性、高强度及生物基来源的共混材料。（1）使用IS对PBST进行共聚改性合成生物基PBIST:通过两步熔融聚合法将天然刚性单体IS引入PBST分子链,成功制备了一系列生物基PBIST共聚酯。结果表明,IS的双环刚性结构可显著提升分子链刚性与热稳定性,T_g随IS含量线性增加,而结晶能力逐渐减弱,当IS含量达20 mol%时完全转变为非晶态。引入6 mol%IS即可提升力学性能,拉伸强度与断裂伸长率分别为36.5MPa和1238.0%,较纯PBST分别提高31%和20%,展现出良好的力学性能。此外,IS单元通过增强酯键水解敏感性显著改善材料降解性能,在中性水解条件下,PBST和PBIST-20共聚酯降解24周后的质量留存率分别为96.7%和95.2%。在脂肪酶环境中,PBST和PBIST-20降解24周后的质量留存率分别为74.9%和52.3%。引入IS单元可显著提高PBST共聚酯的生物降解性,降解速度随IS含量增加而加快,共聚酯的生物降解性能可通过调节IS的添加量进行有效调控。（2）使用ADR对PLA/PBIST（70/30）共混物进行界面增容:通过熔融共混法制备PLA/PBIST/ADR共混材料,揭示ADR对共混体系的增容机制。ADR的环氧基团与PLA及PBIST端基反应生成PLA-g-PBIST接枝或交联结构,凝胶含量随ADR添加量呈先增后降趋势,并于3 wt%ADR时达到峰值28.8%。交联结构与PBIST中异山梨醇单元的刚性结构协同作用,显著提升材料热稳定性,使第二阶段最大热分解温度提高13.5℃,同时熔融温度下降5.1℃及冷结晶温度上升19.1℃,并降低结晶度。流变行为分析表明,ADR的引入促使体系从粘性主导转向弹性主导,储能模量提升,并且PBIST分散相尺寸不断减小,形态发生显著的变化,界面黏结力因支化和交联结构优化而增强。力学性能测试显示,当ADR含量为2～3 wt%时,材料呈现最佳综合性能:拉伸强度达51.0 MPa,保持PLA的75.9%;冲击强度提升至77.3 kJ/m²,为纯PLA的26.7倍;断裂伸长率最高达398.3%。值得注意的是,含3 wt%ADR的共混物经物理老化后仍维持300%以上断裂伸长率和46.3 kJ/m²的冲击强度,表明其优异抗老化特性。（3）使用HDI对PLA/PBIST（70/30）共混物进行界面增容:通过熔融共混法制备PLA/PBIST/HDI复合材料,揭示了HDI对共混体系增容机制。HDI的异氰酸酯基团与PLA及PBIST端羟基反应形成PLA-g-PBIST接枝或交联结构,凝胶含量随HDI添加量呈先增后降趋势,并于3 wt%时达峰值27.8%。交联结构与PBIST中IS单元的刚性结构协同作用,显著提升材料热稳定性,使T_d,5%提高6.7℃,T_d2,max上升2.6℃,同时T_m略微下降0.8℃,T_cc升高6.9℃,且结晶度逐渐降低。流变行为表明,HDI的引入促使体系从粘性主导转向弹性主导,储能模量提升伴随PBIST分散相尺寸不断减小与形态发生显著的变化,界面黏结力因支化和交联结构优化而得到增强。当HDI含量为5 wt%时,材料综合力学性能最优:拉伸强度达48.2 MPa,为PLA的71.7%,断裂伸长率与冲击强度分别提升至434.9%与61.4 kJ/m²,为纯PLA的31.7倍与21.2倍。此外,含5 wt%HDI的共混物经物理老化后仍保持363.2%断裂伸长率和53.6 kJ/m²的冲击强度,表明其抗老化性能显著优于低HDI含量体系。更多还原

【Abstract】 The widespread application of polymer materials has driven the development of modern industry.However,the persistence of traditional petroleum-based polymers in the environment has become an increasingly serious issue,with microplastic pollution posing a threat to aquatic and soil ecosystems.In response to this challenge,policies such as the European Union’s Single-Use Plastics Directive and China’s"Plastic Ban"have strengthened the regulation of non-degradable plastic products.Bio-based degradable polymers have become a research hotspot due to their adjustable degradation cycles and low carbon footprint.Although polybutylene succinate terephthalate（PBST）and polylactic acid（PLA）are mainstream degradable materials,their mechanical properties and degradation performance are insufficient,limiting their high-performance applications.In recent years,bio-based isosorbide（IS）,with its rigid furan ring structure and renewable characteristics,has been widely used for polyester modification to enhance mechanical properties,degradability,and thermal stability.This paper aims to improve the mechanical properties and degradability of PBST through chemical modification with IS,and to melt blend it with PLA.The study also investigates the use of multifunctional epoxy polymer（Joncryl ADR-4468）and hexamethylene diisocyanate（HDI）for compatibilization,with the goal of developing a blend material that balances high toughness,high strength,and is bio-based.（1）IS Copolymerization to Synthesize Bio-based PBIST:Bio-based PBIST copolyesters were successfully prepared through a two-step melt polymerization process by incorporating the naturally rigid IS monomer into the PBST molecular chain.The results show that the bicyclic rigid structure of IS significantly enhances the molecular rigidity and thermal stability.The glass transition temperature（T_g）increased linearly with IS content,while crystallization ability gradually decreased.When the IS content reached 20 mol%,the material completely transitioned to an amorphous state.Introducing 6 mol%IS improved mechanical properties,with tensile strength and elongation at break reaching 36.5 MPa and 1238.0%,respectively,which represented a 31%and 20%increase compared to pure PBST,showcasing good mechanical performance.Additionally,IS units significantly enhanced the degradation performance by increasing the hydrolysis sensitivity of ester bonds.Under neutral hydrolysis conditions,the mass retention rates of PBST and PBIST-20 copolyester after24 weeks of degradation were 96.7%and 95.2%,respectively.In the presence of lipase,the mass retention rates after 24 weeks of degradation were 74.9%for PBST and 52.3%for PBIST-20.The introduction of IS units significantly improved the biodegradability of PBST copolyesters,with degradation rates accelerating as IS content increased.The biodegradation performance of the copolyesters can be effectively controlled by adjusting the IS content.（2）Interface compatibilization of PLA/PBIST（70/30）blends using ADR:PLA/PBIST/ADR blends were prepared via melt blending to investigate the compatibilization mechanism of ADR.The epoxy groups of ADR react with the terminal groups of PLA and PBIST,forming PLA-g-PBIST grafted or crosslinked structures.The gel content increases initially and then decreases with ADR addition,peaking at 28.8%at 3 wt%ADR.The crosslinked structure and the rigid isosorbide units in PBIST synergistically enhance the thermal stability,raising the maximum thermal decomposition temperature in the second stage by 13.5℃,while lowering the melting temperature by 5.1℃ and increasing the cold crystallization temperature by19.1℃,alongside a reduction in crystallinity.Rheological analysis reveals that the introduction of ADR shifts the system from viscosity-dominated to elasticity-dominated behavior,with a rise in storage modulus.The size of the PBIST dispersed phase decreases,and its morphology changes significantly,while interfacial adhesion improves due to the optimized branching and crosslinking structures.Mechanical testing shows that the material exhibits the best overall performance at 2～3 wt%ADR:tensile strength reaches 51.0 MPa（75.9%of pure PLA）,impact strength rises to 77.3kJ/m²（26.7 times that of PLA）,and elongation at break peaks at 398.3%.Notably,the blend with 3 wt%ADR maintains over 300%elongation at break and an impact strength of 46.3 kJ/m² after physical aging,demonstrating outstanding anti-aging properties.（3）Interface compatibilization of PLA/PBIST（70/30）blends using HDI:PLA/PBIST/HDI composites were prepared via melt blending to investigate the compatibilization mechanism of HDI.The isocyanate groups of HDI react with the hydroxyl groups at the ends of PLA and PBIST,forming PLA-g-PBIST grafted or crosslinked structures.The gel content increases initially and then decreases with increasing HDI content,peaking at 27.8%at 3 wt%.The crosslinked structure,in synergy with the rigid IS units in PBIST,significantly enhances the thermal stability of the material,raising T_d,5%by 6.7℃ and T_d2,max by 2.6℃.Simultaneously,T_m decreases slightly by 0.8℃,T_cc increases by 6.9℃,and the crystallinity gradually decreases.Rheological behavior indicates that the introduction of HDI shifts the system from viscosity-dominated to elasticity-dominated,with an increase in storage modulus,accompanied by a reduction in the size and a significant change in the morphology of the PBIST dispersed phase.The interfacial adhesion is enhanced due to the optimization of branching and crosslinking structures.The material exhibits the best overall mechanical performance at 5 wt%HDI:the tensile strength reaches 48.2 MPa（71.7%of pure PLA）,the elongation at break and impact strength increase to 434.9%and 61.4 kJ/m²,respectively,which are 31.7 and 21.2 times that of pure PLA.Additionally,the blend with 5 wt%HDI maintains 363.2%elongation at break and 53.6kJ/m² impact strength after physical aging,demonstrating significantly better anti-aging properties than systems with lower HDI content.更多还原