PLA/PEG共混材料的自增韧研究

采用压力诱导流动成型(PIF)对聚乳酸/聚乙二醇(PLA/PEG)共混物进行加工,研究了PIF对PLA/PEG共混材料的结构和性能影响.结果表明,PLA/PEG的球晶在压力作用下变形,形成无定形相和结晶相相互叠层的砖墙增韧结构,内部的分子链沿着流动方向排列;该砖墙结构使材料的拉伸性能提高了2.5倍,冲击性能提高了30倍;材料的Tg在压力诱导流动加工后升高.     

淀粉/聚乳酸/聚己内酯共混材料的性能研究

研究了淀粉/聚乳酸接枝马来酸酐/聚己内酯接枝马来酸酐(starch/PLA-g-MAH/PCL-g-MAH)共混材料的主要性能。结果表明:PCL-g-MAH的加入有效增强了共混物的韧性,且将两聚酯接枝马来酸酐实现了对共混物的增容,使starch/PLA-g-MAH/PCL-g-MAH共混体系的力学性能和耐水性能比淀粉/聚乳酸/聚己内酯(starch/PLA/PCL)共混物显著提高。同时,增容后的共混物仍具备良好的可生物降解性能。     

聚乳酸/热塑性淀粉多组分生物可降解共混物研究进展

全生物基聚乳酸/淀粉生物可降解材料,同时具有聚乳酸(PLA)的高性能和淀粉(TPS)的低成本,是近年来受到广泛关注的全生物降解高分子体系。由于淀粉具有较强的亲水性,与PLA基体难以相容,使界面的黏附性较差,导致材料的性能恶化; PLA/TPS共混物体系研究的焦点主要是通过改善组分的界面相容性,提高共混物的力学性能。文章对聚乳酸/热塑性淀粉(PLA/TPS)共混物的制备和性能进行介绍,对PLA/TPS二元共混物的力学性能进行了概述,主要总结了增塑剂、无机粒子对PLA/TPS共混物界面结构和力学性能的影响,详细阐述了接枝(嵌段)共聚物、小分子化合物增容PLA/TPS共混物多组分体系的研究进展。高性能聚乳酸/淀粉生物可降解多组分共混物是一种极具开发前景的新型生物可降解塑料。     

增塑剂对聚乳酸/热塑性淀粉共混物结构与性能的影响

采用柠檬酸三丁酯(TBC)、聚乙二醇(PEG)增塑聚乳酸(PLA)/热塑性淀粉(TPS)共混体系,调节PLA的流变性能,改善PLA与TPS相容性、熔融共混特性和共混物的微观结构和力学性能.结果表明:TBC的改性效果比PEG更佳;TBC能增加TPS分散均匀性,相分散尺寸明显变小;TBC改性PLA/TPS的拉伸强度和断裂伸长率明显提高.吸水率较小.     

聚乙二醇对聚乳酸/热塑性淀粉复合材料性能的影响

采用注塑法制备了聚乙二醇(PEG)改性的聚乳酸(PLA)/热塑性淀粉(TPS)复合材料,研究了PEG对PLA/TPS复合材料的加工流变性能、力学性能的影响,采用差示扫描量热(DSC)仪和扫描电子显微镜(SEM)进行微观结构分析并研究了加工工艺对复合材料性能的影响.结果表明,当PEG的质量分数为3%时,复合材料的力学性能最佳;DSC测试和SEM分析表明,PEG的加入提高了复合材料的塑性, 改善了其相容性.     

PLA-g-ST对聚乳酸/热塑性淀粉共混材料性能的影响

以淀粉和乳酸为原料合成相容剂聚乳酸接枝淀粉(PLA-g-ST),并通过熔融共混的方法制备聚乳酸(PLA)/热塑性淀粉(FPTPS)共混材料。研究了PLA-g-ST用量对PLA/FPTPS共混材料力学性能、微观形貌和热性能的影响。结果表明,PLA-g-ST改善了PLA/FPTPS共混材料的相容性;当PLA-g-ST用量为7%时,拉伸强度为19.7MPa,比未添加PLA-g-ST的共混材料提高了20.9%,断裂伸长率为62.1%,比未添加PLA-g-ST的共混材料提高了16.7%,冲击强度为7.6 kJ/m2,比未添加PLA-g-ST的共混材料提高了11.8%;当PLA-g-ST用量为9%时,弯曲强度为19.2 MPa,比未添加PLA-g-ST的共混材料提高了6.6%。     

PLA/淀粉增容增塑的研究进展

聚乳酸(PLA)/淀粉复合材料是一种新型的绿色材料,生物降解性能优良,但是聚乳酸(PLA)/淀粉复合材料的力学性能较差,文章通过在共混体系中引入小分子增塑剂或大分子增塑剂以及通过发生酯化反应,使其分别具有外增塑和内增塑PLA/淀粉复合材料的作用,一步法反应增容不仅降低了淀粉结晶度,而且在界面处形成"架桥";两步法接枝形成与淀粉或PLA具有相同结构的共聚物PLA/淀粉复合材料,改善了复合材料的相容性。增容增塑聚乳酸(PLA)/淀粉复合材料能够提高复合材料的界面作用强度,降低PLA的脆性,改善淀粉的流动性能,极大地提高了复合材料的力学强度,并进一步总结了增容增塑改善PLA/淀粉复合材料界面作用的机理。     

淀粉/PLA可降解复合材料性能研究

采用熔融共混技术制备淀粉/聚乳酸(PLA)复合材料.以制备出的复合材料力学性能、转矩流变性能和微观结构作为指标,研究了淀粉的含量、甘油的加入量对淀粉/PLA共混材料性能的影响.结果表明,以PLA为基体材料,淀粉质量分数为30％,甘油/淀粉质量分数为30/100时,制备出的淀粉/PLA复合材料有较好的性能.     

GMA接枝聚乳酸对聚乳酸/淀粉共混物性能的影响

首先制备了聚乳酸与甲基丙烯酸缩水甘油酯(GMA)的接枝共聚物(PLA-g-GMA)和丁二酸酐功能化改性淀粉,并利用红外光谱和核磁共振谱对二者的结构进行了表征。进一步通过熔融共混法制备了聚乳酸(PLA)/改性淀粉/PLA-g-GMA三元共混物,并利用转矩流变仪、扫描电子显微镜、差示扫描量热仪和万能拉力试验机等手段研究了接枝物对共混物的流变性能、形貌结构、热性能以及力学性能的影响。结果表明,PLA-g-GMA的加入促进了淀粉在PLA基体中的分布,淀粉粒径最小在0.5μm以下;同时也抑制了PLA的热降解,提高材料的力学性能,尤其是断裂伸长率,最高达到260%;另外也抑制了PLA的结晶。     

基于溶液插层和表面接枝的PLA/PLA-g-OMMT纳米复合材料制备及其性能研究

采用聚乙二醇(PEG)通过溶液插层对钠基蒙脱土(Na-MMT)进行有机化改性,并利用左旋乳酸(L-LA)和异佛尔酮二异氰酸酯(IPDI)对所得有机蒙脱土(OMMT)的表面进行接枝改性,得到聚乳酸(PLA)接枝有机蒙脱土PLA-g-OMMT;然后通过溶液共混的方式制备出PLA/PLA-g-OMMT纳米复合材料。结果表明:通过溶液插层和表面接枝对Na-MMT进行修饰,然后将其与PLA复合,可以同时提高PLA材料的强度和韧性。其中当PLA-g-OMMT用量为PLA的2%时,其改性效果最好,复合材料的拉伸强度和断裂伸长率分别达到41.84 MPa和8.01%。另外,PLA-g-OMMT的引入能够改善复合材料的结晶性能,并可使材料的玻璃化转变温度降低。     

Plasticizing effect of poly(ethylene glycol)s with different molecular weights in poly(lactic acid)/starch blends

Binary and ternary blends composed of poly(lactic acid) (PLA), starch, and poly(ethylene glycols) (PEGs) with different molecular weights (weight‐average molecular weights = 300, 2000, 4000, 6000, and 10, 000 g/mol) were prepared, and the plasticizing effect and miscibility of PEGs in poly(lactic acid)/starch (PTPS) or PLA were intensively studied. The results indicate that the PEGs were effective plasticizers for the PTPS blends. The small‐molecule plasticizers of PEG300 (i.e., the M_w of PEG was 300g/mol) and glycerol presented better plasticizing effects, whereas its migration and limited miscibility resulted in significant decreases in the water resistance and elongation at break. PEG2000, with a moderate molecular weight, was partially miscible in sample PTPS3; this led to better performance in water resistance and mechanical properties. For higher molecular weight PEG, its plasticization for both starch and PLA was depressed, and visible phase separation also occurred, especially for PTPS6. It was also found that the presence of PEG significantly decreased the glass‐transition temperature and accelerated the crystallization of the PLA matrix, depending on the PEG molecular weight and concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41808.     

Kinetics of water absorption and thermal properties of poly(lactic acid)/organomontmorillonite/poly(ethylene glycol) nanocomposites

Poly(lactic acid) (PLA)/organomontmorillonite (OMMT) nanocomposites were prepared by a melt intercalation technique. The effects of OMMT and poly(ethylene glycol) (PEG) on the thermal properties and water absorption behavior of PLA were investigated. The melting temperature and degree of crystallinity were comparable for the PLA and its nanocomposites. The glass transition temperature and crystallization temperature of PLA were decreased by the addition of PEG. X‐ray diffraction results revealed the formation of PLA nanocomposites, as the OMMT was partly intercalated and partly exfoliated. The maximum moisture absorption of PLA was increased in the presence of PEG and the diffusivity of the PLA nanocomposites decreased with increasing concentrations of PEG. However, the activation energy of the nanocomposites increased as the loading of PEG increased. These results indicated that the incorporation of OMMT and PEG enhanced the water‐barrier properties of the PLA. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Influence of blocked polyisocyanate on thermomechanical, shape memory and biodegradable properties of poly(lactic acid)/poly(ethylene glycol) blends

A series of shape memory biodegradable blends from poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were prepared by solution casting method. Ethyl cellosolve-blocked polyisocyanate (EC-bp) was synthesized and used as a cross-linker to obtain cross-linked PLA/PEG blends. The chemical structure of the prepared composite was confirmed by Fourier transform infrared spectra. Thermomechanical, thermal and shape memory properties of the blends were investigated and compared by dynamic mechanical analysis, thermogravimetric analysis and shape memory testing. The results showed that EC-bp cross-linked PLA/PEG blends had better thermal and thermomechanical properties than non-cross-linked blends and displayed good shape memory effects in both shape fixity rate and shape recovery rate. Moreover, the effect of EC-bp addition on the rate of biodegradable degradation in a phosphate buffer solution (pH 7.4) was studied at 37?°C. The prepared cross-linked PLA/PEG blends demonstrated better degradation resistance compared to the non-cross-linked blends.     

聚乙二醇对聚乳酸/淀粉纳米晶复合材料性能的影响

以聚乳酸（PLA）和淀粉纳米晶（SNC）为主要原料,聚乙二醇（PEG）为增塑剂,采用溶剂蒸发法制备PLA/SNC和PLA/SNC/PEG复合材料,通过差示扫描量热仪（DSC）、热台偏光显微镜（PLM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）等研究了PEG对复合材料结晶行为、力学性能及界面相容性的影响。结果表明,PEG能够与SNC协同促进PLA结晶,使PLA/SNC/PEG复合材料的结晶速率明显提高;PEG的添加未改变PLA/SNC复合材料的结晶结构;随着PEG含量的增加,PLA/4 %（质量分数,下同）SNC复合材料的拉伸强度先升高后下降,断裂伸长率不断提高;当PEG含量为2 %时,PLA/4 %SNC/2 %PEG复合材料的力学性能最佳,拉伸强度为47.86 MPa,断裂伸长率为10.20 %,PLA与SNC间界面相容性得到改善。     

The morphology,rheological, and mechanical properties of wood flour/starch/poly(lactic acid) blends

An entirely biosourced blend composed of poly(lactic acid) (PLA), starch, and wood flour (WF) was prepared by a co‐extruder with glycerol as a plasticizer. The morphology, rheological properties, and mechanical properties of the WF/starch/PLA blends were comprehensively analyzed. The results showed that with the decrease of the starch/WF ratio, the morphology experienced a large transformation, and the compatibility of the blends was found to be superior to other blends, with a starch/wood flour ratio of 7/3. The dynamic mechanical thermal analysis (DMA) results demonstrated the incompatibility of the components in WF/starch/PLA blends. Following the decrease of the starch/WF ratio, the storage modulus (G″) and the complex viscosity (η*) of the blends increased. The mechanical strength first increased, and then decreased with the increase of the WF concentration. The water absorption results showed that the water resistance of the blends was reduced with the lower starch/WF ratio. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44743.     

Compatibility improvement of poly(lactic acid)/thermoplastic starch blown films using acetylated starch

The present research aims to improve the compatibility between relatively hydrophobic poly(lactic acid) (PLA) and hydrophilic thermoplastic starch (TPS) and the properties of the PLA/TPS blends by replacing TPS from native cassava starch (TPSN) with TPS from acetylated starch (TPSA). The effects of the degree of acetylation (DA) of acetylated starch, that is, 0.021, 0.031, and 0.074, on the morphological characteristics and properties of PLA/TPS blend are investigated. The melt blends of PLA and TPS with a weight proportion of PLA:TPS of 50:50 are fabricated and then blown into films. Scanning electron microscopy confirms the dispersion of TPS phase in the PLA matrix. Better dispersion and smaller size of the TPS phase are observed for the PLA/TPSA blend films with low DA of acetylated starch, resulting in improved tensile and barrier properties and increased storage modulus, thermal stability, and T_g, T_cc, and T_m of PLA. Elongation at break of the PLA/TPSA blend increases up to 57%, whereas its water vapor permeability and oxygen permeability decrease about 15%. The obtained PLA/TPSA blend films have the potential to be applied as biodegradable flexible packaging.     

苹果酸对聚乳酸/热塑性淀粉共混物结构与性能的影响

将天然淀粉用甘油改性后制得了热塑性淀粉(TPS),再通过熔融共混法制备了聚乳酸(PLA)/TPS共混物。通过SEM、TG、DSC分析和拉伸性能、吸水性能、流变性能测试,研究了苹果酸对TPS和PLA/TPS共混物结构和性能的影响。结果表明:苹果酸能促进淀粉酸解,使TPS分散相尺寸减小,在PLA基体中的分布更加均匀;苹果酸能提高PLA/TPS共混物的拉伸性能;苹果酸对PLA/TPS共混物的玻璃化转变温度、熔融温度及冷结晶温度影响较小;少量的苹果酸可降低PLA/TPS共混物的吸水率。     

Biodegradable polymer blends of poly(L‐lactic acid) and gelatinized starch

Gelatinized starches were prepared with various content of glycerol and were investigated in terms of the effect of the glycerol addition on characteristics of starch and its blends. Poly (L‐lactic acid) (PLA) with various ratios of linear/star shaped PLA and starch gelatinized with various ratios of water/glycerol were melt‐blended by using twin screw mixer. The blends were characterized by DSC thermal analysis, tensile test and morphological analysis. Gelatinization of starch was found to lead to destruction or diminution of hydrogen bonding in granules and a decrease of crystallinity of starch. DSC data showed that starch played a role as a nucleating agent and glycerol as plasticizer contributed to an improvement in crystallinity in PLA blends. When the content of starch increased, the size of spherulites in PLA blends was smaller and less regular. In the case of PLA/pure starch blends, the voids appeared, which were formed by the separation of starch particles from the matrix. But for PLA/gelainized starch blends, these voids were not observed. In the case of blends with linear PLA and starch gelatinized with water/glycerol ratio of 100/40, the greatest superiority of mechanical properties was shown and the toughness was improved compared with PLA/pure starch blends.