L-赖氨酸乙酯二异氰酸酯的合成

以L-赖氨酸为原料经乙酯化后与三光气反应合成了L-赖氨酸乙酯二异氰酸酯。该方法避免了使用剧毒的光气,通过加入吡啶除去了反应过程中产生的大量氯化氢,克服了高温下氯化氢对设备的腐蚀,反应条件温和,处理简捷,总收率为75%,适用于工业化生产并可被借鉴用于其它氨基酸异氰酸酯的制备。     

PPC与IPDI原位聚合增韧聚乳酸

以聚碳酸亚丙酯多元醇(PPC)和异佛尔酮二异氰酸酯(IPDI)为反应性增韧单体,在熔融共混过程中原位聚合生成聚氨酯(PU)增韧相,制备了新型增韧PLA/PU材料。通过FTIR、万能电子试验机、TG、DSC、SEM测试研究了单体用量对PLA共混物加工性、相容性及韧性的影响规律。结果表明:随着增韧单体用量的增加,共混物中PLA组分的冷结晶温度(Tc)和玻璃化转变温度(Tg)降低;当n(NCO)/n(OH)=1/1,PPC用量为30%时,共混物的断裂伸长率和冲击强度比纯PLA分别增加71.8倍和15.6倍;原位聚合物对PLA有较好的增韧效果。     

二异氰酸酯封端聚酯多元醇型固化剂合成反应动力学的研究

以低分子聚酯多元醇与二异氰酸酯合成新型聚氨酯固化剂,分别研究了甲苯二异氰酸酯（TD I）、二苯基甲烷二异氰酸酯（MD I）与低分子聚酯多元醇的反应动力学。结果表明,TD I封端低分子聚酯多元醇的反应为二级反应,反应活化能为51.7 kJ/mol;MD I封端低分子聚酯多元醇的反应在反应温度低于70℃时也为二级反应,反应活化能为27.6 kJ/mol。     

淀粉原位熔融接枝聚乳酸反应研究

利用二甲基亚砜将淀粉糊化,然后加入乳酸和催化剂,在95℃下减压反应,制备了聚乳酸(PLA)与淀粉的接枝共聚物。通过红外光谱和X射线衍射对接枝产物进行了表征,采用吸光度对比法计算了接枝产物的接枝率,并分析了真空反应工艺对接枝反应的影响。结果表明:在温和的条件下减压反应可得到PLA与淀粉的接枝共聚物;PLA和淀粉的特征峰的吸收强度与其含量成正比,接枝产物中PLA的接枝率为1.969%;真空反应工艺在接枝反应中具有重要意义。     

聚乳酸／二异氰酸酯反应挤出扩链及其产物性能研究

以溶液法直接合成低相对分子质量聚乳酸为基础，在双螺杆挤出机上与二苯基甲烷二异氰酸酯进行反应挤出，制得高相对分子质量的聚乳酸基聚氨酯，研究了不同NOO／OH摩尔比对产物相对分子质量、热性能和力学性能的影响。结果表明，用反应挤出法对聚乳酸进行扩链是可行的，扩链后聚乳酸的黏均相对分子质量由9．19×10^4提高到23．6×10^4，韧性提高，拉伸断裂强度增大近1倍。     

含磷含氮多元醇反应型阻燃剂

阻燃聚氨酯硬泡所用的反应型阻燃剂主要有:含磷含氮多元醇、含磷含溴多元醇、含磷含氯多元醇、含磷多元醇、含溴多元醇、含氯多元醇和含氮多元醇等。其中,含磷含氮多元醇研究开发较早,尤其是作为其典型代表的O,O—二乙基—N,N—双(2     

丙烯酸酯增韧聚乳酸的制备与性能

采用1,6-己二醇二丙烯酸酯(HDDA)和聚乳酸(PLA)为原料,通过反应共混法制备了PLA/HDDA共混物,并利用拉力试验机、冲击试验机、扫描电子显微镜、差式扫描量热仪和偏光显微镜研究了HDDA含量对共混物力学性能、断面形貌、热性能和结晶性能的影响。结果表明,HDDA对PLA具有良好的增韧效果,随着HDDA含量的增加,共混物的断裂伸长率和冲击强度显著提高;当HDDA含量为20%时,冲击强度达到8. 2 kJ/m~2,断裂伸长率为62. 8%,而拉伸强度仍保持在较高水平(39. 8 MPa)。HDDA的加入使共混物的冲击断面变粗糙,断裂形态为韧性断裂;随着HDDA含量的增加,共混物中PLA相的玻璃化转变温度逐渐降低,冷结晶温度先升高后降低,结晶度则先减小后增大。     

聚磷酸铵与聚乙二醇增韧阻燃聚乳酸研究

采用聚磷酸铵(APP)对聚乳酸进行阻燃改性,并利用两种不同相对分子质量的聚乙二醇(PEG2000和PEG4000)进行增韧改性,最终制备出了增韧阻燃聚乳酸复合材料。结果表明:PEG2000和PEG4000的加入不同程度地提高了复合材料的断裂伸长率和冲击强度,分别提高到37.1%,2.65kJ/m2和26.7%,3.15kJ/m2;APP的加入使得复合材料的阻燃性能显著提高,极限氧指数最高达到了29.2%,垂直燃烧测试达到UL-94V-0等级。扫描电镜结果表明:复合材料的断面微观形貌由脆性断裂变成了韧性断裂,同时APP在基体中的分散性得到了提高。     

聚醚胺和聚醚多元醇对环氧/酸酐体系的原位增韧作用

研究了聚醚胺PEA2000和聚醚多元醇PPG2000对环氧/酸酐体系的原位增韧作用,并探讨了它们的增韧机理。通过对比研究PEA2000和PPG2000在不同含量时对环氧/酸酐体系固化物的力学性能及热变形温度的影响,发现PEA2000对环氧/酸酐体系的增韧效果要优于PPG2000,最佳用量为10 phr,此时固化体系的拉伸强度提高了2.18 MPa,断裂伸长率提升了31.3%,冲击强度提高了39.2%。通过SEM对PEA2000和PPG2000的含量为10 phr时的固化样条的冲击断面进行研究,发现在固化体系中PEA2000形成了均相体系,而PPG2000形成了分相体系。通过对PEA2000和PPG2000增韧机理的探究发现二者增韧效果不同的主要原因是因为端基反应活性不同而导致他们与环氧网络相容性存在差异。     

聚乳酸增韧改性研究进展

主要介绍了聚乳酸的化学增韧改性(共聚改性)和物理增韧改性(增塑、共混与无机刚性粒子复合),综述了近年来国内外聚乳酸增韧改性的研究现状及进展,并对今后聚乳酸增韧改性提出了建议。     

Poly(lactic acid) Toughening with a Better Balance of Properties

Poly(lactic acid) (PLA) toughening is often associated with significant modulus and/or strength losses making it unsuitable for many consumer and biomedical applications. The major objective of this research was to toughen PLA without significant loss in modulus and strength and to introduce reactive acid groups using reactive blending of PLA with a combination of polymers. PLA was reactive blended with poly(acrylic acid) (PAA) followed by physical blending with poly(ethylene glycol) (PEG) in solution. The modified PLA was extruded into films using a co‐rotating twin‐screw extruder and characterized using tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA). This technology resulted in films with a ten‐fold increase in toughness compared to neat PLA with little or no decrease in strength and modulus.

     

A New Approach to Supertough Poly(lactic acid): A High Temperature Reactive Blending

A novel approach to PLA toughening is proposed in this study. Poly(lactic acid) (PLA) is toughened using poly(ethylene‐n‐butylene‐acrylate‐co‐glycydyl methacrylate) (EBA‐GMA) as a reactive compatibilizer with the aid of an epoxy‐based chain extender. It is found that the toughening effect of EBA‐GMA in the binary blend investigated is strongly influenced by blending temperature. Blending at high temperatures which are non‐typical for PLA processing (over 250 °C) allows toughness to be increased by an order of magnitude when compared to the toughness of blends prepared at low temperatures (below 200 °C). This effect is attributed to a combination of factors, namely an increasing rate of reactive bonding between PLA and EBA‐GMA at elevated temperatures and enhanced interfacial adhesion between PLA and EBA‐GMA phases. DSC studies show that PLA/EBA‐GMA bonding on the interface acts as an efficient nucleator for PLA. The nucleation ability of the PLA/EBA‐GMA interface strongly depends on blend processing temperature and gradually increases with increasing blending temperature. The PLA/EBA‐GMA interface shows its highest nucleation ability at 250 °C.

     

Effect of Blending Procedure on Tensile and Degradation Properties of Toughened Biodegradable Poly(lactic acid) Blend with Poly(trimethylene terephthalate) and Reactive Compatibilizer

This research focuses on brittleness improvement of biodegradable poly(lactic acid) (PLA) by reactive melt blending with poly(trimethylene terephthalate) (PTT). First, PLA is simultaneously blended with PTT and a reactive compatibilizer, poly(ethylene‐co‐glycidyl methacrylate) (PEGMA), (one‐step blending procedure). In the PLA/PTT/PEGMA blend, PEGMA mainly disperses in the PLA matrix phase, and the blend shows unimproved tensile properties. To increase the reaction between PTT and PEGMA, PEGMA is sequentially blended with PTT then PLA (two‐step blending procedure). This procedure is effective in drastically enhancing elongation at break of the blend. The strain at break of the blend formed by two‐step blending is significantly improved because the blending procedure affects the blend morphology. PLA‐g‐PEGMA‐g‐PTT graft copolymer is formed at the interface between PLA and PTT during reactive melt blending with PEGMA when the two‐step blending procedure is employed as a blending method which is confirmed by Fourier transform infrared spectroscopy and viscosity measurement. Such features bring about craze formation during tensile test and this is the reason why the toughening is achieved by the two‐step blending procedure.     

聚乳酸增韧及结晶改性研究进展

综述了近期在聚乳酸（PLA）材料的成核结晶、立构复合、增韧与耐热改性方面的工作,重点探讨了成核剂化学结构、快速立构复合技术、反应性增容和退火等技术对PLA材料力学性能的影响,并对PLA材料的应用和发展方向进行了展望。     

反应挤出合成聚乳酸与脱挥技术研究

主要介绍了反应挤出合成聚乳酸的技术特点和脱挥技术应用;分析了反应挤出合成过程中脱挥处理的关键点和影响因素。相比传统的聚乳酸合成技术,因其具有突出的优势,预计是今后聚乳酸合成发展的研究热点。     

“核-壳”结构增强增韧聚乳酸机理研究

研究了滑石粉和硅藻土与增韧复配体系并用增韧聚乳酸(PLA)复合材料的机理。结果表明,颗粒状硅藻土与增韧复配体系形成的"核-壳"结构比非"核-壳"的多相共混结构对PLA有优良的增韧效果,而片状滑石粉填充体系则相反,其非"核-壳"的多相共混结构材料具有较好的韧性。     

Green Engineered Polypropylene Biodegradable Fibers Through Blending with Recycled Poly(lactic) Acid Plastic Wastes

The modification of polypropylene (PP) fibers via blending with recycled poly(lactic) acid (r-PLA) flakes by a melt spinning method was investigated. Mechanical and morphological properties, biodegradability, differential scanning calorimetery (DSC) analysis, and dyeing behavior were carried out for physical and structural characterization of the fiber samples. The results showed that the PP/r-PLA blend fibers with the different blend ratios could be successfully melt spun along with suitable continuity. Acceptable tenacity and initial modulus and suitable biodegradability were obtained for the modified PP fibers. Dye uptake of the modified PP fiber samples was improved and the washing and light fastness of some them were excellent.     

超支化聚酰胺酯对聚乳酸增韧改性的研究

采用熔融共混的方法,用生物可降解的超支化聚酰胺酯(HBP)对聚乳酸(PLA)进行增韧改性,制备出具有良好韧性的PLA复合材料。对不同HBP含量的共混物的红外光谱、热性能和力学性能进行了测试和分析。红外光谱显示PLA和HBP间存在氢键作用。HBP的加入使PLA的结晶度从30.99%降低到18.58%。当HBP含量增加到10%时,PLA共混物的拉伸强度略有提高,且断裂伸长达到43.06%。结果表明:HBP的加入对PLA起到了很好的增韧作用。     

聚酰胺弹性体增韧聚乳酸改性研究

选用聚酰胺弹性体(聚酰胺和聚氧乙烯的共聚物,PAE)与聚乳酸(PLA)熔融共混进行增韧改性。结果表明,当PAE弹性体含量在20%～30%(质量分数,下同)之间时,共混体系发生脆韧转变,最大冲击强度达到67.6J/m,但拉伸强度和模量大幅度下降;PAE弹性体含量为5%～10%时共混体系的拉伸强度保持率最高,而且断裂伸长率提高近40倍,综合性能较好;虽然扫描电子显微镜照片显示共混体系为两相分离,但是差示扫描量热分析数据均表明,随着PAE弹性体含量的增加,共混体系的玻璃化转变温度和熔点发生相应变化,证明该共混体系为半溶混性,即两相间存在一定的相互作用;热失重分析数据显示,PAE弹性体在一定程度上提高了PLA的热降解温度。