原位反应增容制备可生物降解PLA/PCL复合材料

基于原位反应增容原理制备了一种可生物降解的聚乳酸(PLA)/聚己内酯(PCL)共混材料。探究了PLA/PCL不同配比及相容剂乙烯-丙烯酸丁酯-甲基丙烯酸缩水甘油酯(EBA-GMA)(8份)对增韧效果的影响,目的是研究设计一种增韧效果最佳的PLA/PCL/EBA-GMA可降解材料。并采用平板流变仪、傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)及差示扫描量热法(DSC)对其反应机理、微观形貌及热性能进行了表征。结果表明,在不加相容剂时,PLA/PCL(80/20)能取得最好的增韧效果;加入8份相容剂后,PLA/PCL(85/15)的缺口冲击强度达75.4 kJ/m^2,增韧效果最好。     

紫外线吸收剂在PLA/PBAT生物降解薄膜中的应用

通过挤出共混造粒、吹塑成型工艺制备出了聚乳酸(PLA)/聚对苯二甲酸-己二酸丁二醇酯(PBAT)完全生物降解薄膜。研究了一种二苯甲酮类紫外线吸收剂对PLA/PBAT薄膜抗紫外老化的作用。采用万能拉力试验机、紫外-可见吸光光谱仪、差示扫描量热法(DSC)对PLA/PBAT薄膜在紫外老化过程中的性能进行了测试和表征。结果表明,选择的紫外线吸收剂能有效减缓PLA/PBAT薄膜在老化过程中力学性能的下降。紫外老化更易发生在薄膜的无定型区,该紫外线吸收剂能明显降低薄膜在老化过程中结晶度的变化。同时,添加该紫外线吸收剂能大幅度降低薄膜在紫外老化过程中产生的凝胶含量。     

完全生物降解塑料PLA/PPC合金的结构与性能研究

利用机械共混法,将聚乳酸(PLA)与聚丙撑碳酸亚丙酯(PPC)熔融共混,制备了完全生物降解塑料PLA/PPC合金,并用FTIR、流变仪等手段研究了其结构、力学性能和流变性能。结果表明该共混体系具有良好的相容性、力学性能和熔体流动性,PLA与PPC之间存在着较强的相互作用,PPC的加入使体系拉伸强度下降幅度不大,断裂伸长率升高到23.8%,比纯PLA提高近20倍。共混体系的黏度亦随着PPC的加入逐渐增大,PLA/PPC(50/50)体系的黏流活化能为37.1kJ/mol,同时在一定的温度范围内,提高切应力也会使体系黏度下降。     

聚乳酸/淀粉共混复合材料研究进展

综述了近年来国内外聚乳酸/淀粉共混复合材料的研究进展,并对聚乳酸/淀粉共混复合材料的发展前景进行了展望。     

聚乳酸/纤维素及其衍生物共混复合材料的研究进展

介绍了聚乳酸(PLA)/纤维素、PLA/天然植物纤维、PLA/纤维素酯和PLA/纤维素醚共混复合材料最新的研究进展,综述了复合材料在相容性、分散性、力学性能和降解特性等方面存在的优点和缺点,为此类共混复合材料的进一步研究指明方向。     

聚乳酸/无机填料复合材料结构与性能的研究

采用密炼器熔融共混法,将聚乳酸(PLA)分别与碳酸钙(CaCO3)、蒙脱土(MMT)及滑石粉(Talc)共混制备成生物降解复合材料,研究了PLA/无机填料共混物的力学性能、断面微观结构及结晶性能。结果表明:CaCO3、MMT和Talc均降低了PLA的断裂伸长率;Talc和CaCO3对PLA的拉伸强度影响不大,MMT明显降低了PLA的拉伸强度;Talc和CaCO3相对MMT在PLA基体中的分散较均匀;CaCO3和MMT改善PLA结晶性能的效果不明显,而Talc大大提高了PLA的结晶性能使,PLA的结晶温度下降约20℃结,晶度提高近3%。     

Fatigue behaviour of multiblock thermoplastic elastomers. 2. Dynamic creep of poly(aliphatic/aromatic-ester) copolymers

The ‘dynamic creep’ behaviour of poly(aliphatic/aromatic-ester) (PED) multiblock copolymers has been evaluated by the hysteresis measurements method. The effect of the hard/soft segments concentration on the microphase separation in PED copolymers was determined by means of differential scanning calorimetry. The ‘dynamic creep’ of PED copolymers has been compared with poly(ether-ester) and segmented polyurethanes indicating on the good creep behaviour of PEDs compared to those materials. It was found that the hard segment content influences the creep behaviour of PED copolymers at ambient and elevated temperature indicating that stiffer materials are less susceptible to environmental conditions than polymers containing a high amount of the soft phase. PED copolymers compare very well with commercially available poly(ester-ethers) and show much lower creep compared to poly(ether-urethanes).     

Tensile and elastic properties of thermoplastic elastomers based on PTMO and tetra-amide units

The tensile and elastic properties of melt spun threads of segmented copolymers based on T6T6T-dimethyl (5-16 wt%) and PTMO₁₀₀₀/DMT of different lengths (3000-10,000 g/mol) are very good. Stress-strain measurements show that extruded threads of these polymers have high fracture strains (>1000%) and little strain hardening. The modulus and yield stress increase with increasing T6T6T content. The modulus decreases with increasing drawing-strain as a result of the breaking up of the crystalline network (strain softening). The compression set and tensile set increase with increasing T6T6T content and are low. The uniformity of T6T6T has little influence on the properties. At a soft segment length of 6000 g/mol a fibre with a tensile set of 5%, flow temperature of 200 °C and rubber modulus of 7 MPa is feasible, which can compete with commercial materials.     

Fatigue behaviour of multiblock thermoplastic elastomers. 1. Stepwise increasing load testing of poly(aliphatic/aromatic-ester) copolymers

Fatigue properties of poly(aliphatic/aromatic-ester) (PED) multiblock copolymers were evaluated based on the hysteresis measurement method. This method allows the digitalization of the hysteresis loop and beside the determination of stress and strain-related parameters, stored energy, lost energy, damping and dynamic creep behaviour can be determined. The correlation between hard/soft segment concentration of PED copolymers, and fundamental parameters, which derived during the cyclic loading (using stepwise increasing load testing, SILT), has indicated a good load-carrying performance of polymers containing a high amount of the hard phase. PED copolymers compare very well with commercially available poly(ester-ethers) and show a much better performance than poly(ester-urethanes) when samples are loaded at the same fatigue stress level relative to their ultimate tensile strength. Softer PEDs and poly(ether-urethane) copolymer show much higher values of dynamic modulus than chemically cross-linked silicone elastomer. Therefore, these multiblock copolymers can be considered as good candidates for applications where materials are subjected to oscillatory deformations (for example passive flexor tendon reconstruction).     

Fatigue behaviour of multiblock thermoplastic elastomers. 3. Stepwise increasing strain test of poly(aliphatic/aromatic-ester) copolymers

The fatigue behaviour of poly(aliphatic/aromatic-ester) (PED) multiblock copolymers has been evaluated using the hysteresis loop method. Stepwise increasing strain test (SIST) was performed at a frequency of 1 Hz. The strain levels were varied with increasing extension steps: 3, 5, 10, 15, 20, 25 and 30% of the initial strain, while minimum stress has been set at a constant value of 0.1 MPa. It has been found that soft PEDs show a very good stress relaxation due to the fact that they contain high amounts of the amorphous phase and their soft segments do not crystallize. PED copolymers, especially those containing low amounts of crystalline hard domains showed very good damping properties at small strain levels. It has also been found that PED's ability to store and dissipate energy is a function of the hard segment concentration. This method proved to be a useful tool for determining the changes in the material properties of PEDs and other thermoplastic elastomers during deformation.     

聚乳酸（PLA）／己二酸-对苯二甲酸-丁二酯共聚物（PBAT）／乙酰化柠檬酸三丁酯（ATBC）共混物的结晶行为

采用熔融共混法制备聚乳酸（PLA）／己二酸-对苯二甲酸-丁二酯共聚物（PBAT）／乙酰化柠檬酸三丁酯（ATBC）共混物。用差示扫描量热仪（DSC）和偏光显微镜（POM）分析了乙酰化柠檬酸三丁酯（ATBC）对共混物PLA结晶行为的影响。结果表明当PLA／PBAT含量为80／20（质量比）时,随着ATBC量的增加,PLA的Tg、Tc和Tm降低,结晶度提高,球晶生长速率增加。     

增塑剂对生物降解塑料聚乳酸结晶形态的影响

采用熔融共混方法制备了聚乙二醇(PEG)和聚乳(酸PLA)的共混物,并借助差示扫描量热仪和广角X射线衍射仪研究了在80~140℃等温结晶时PEG对PLA结晶形态和熔融行为的影响。结果表明:100℃以上时PLA的结晶度随结晶温度的升高逐渐增加;100℃以下时PLA的结晶度随PEG含量的增加逐渐增大。110℃以下时,晶面间距随结晶温度的升高和PEG含量的增加而逐渐减小;110℃以上时,晶面间距保持不变;当加入15%的PEG时PLA的晶面间距不受结晶温度的影响结,晶生成的是稳定的α晶。     

Polylactide compositions. Part 1: Effect of filler content and size on mechanical properties of PLA/calcium sulfate composites

Starting from calcium sulfate (gypsum) as a fermentation by-product of lactic acid fermentation, novel high performance composites have been produced by melt-blending polylactide (PLA) and previously dried calcium sulfate hemihydrate in a Brabender bench scale kneader at 190 °C. Due to PLA sensitivity towards hydrolysis, it has first been demonstrated that formation of β-anhydrite II (AII) by adequate thermal treatment of calcium sulfate is a prerequisite. Then, the effect of filler content and mean diameter on thermal, mechanical and impact properties has been examined together with the morphology of the resulting materials. It shows that high tensile performances and impact strength are maintained up to a filler content of 20 wt% without any increase of PLA crystallinity. Interestingly enough and provided that AII particles with a mean diameter of ca. 10 μm were considered as PLA fillers, tensile and impact properties proved to be maintained at a very acceptable level at filler content as high as 50 wt%. Such remarkable mechanical behavior can be accounted for by the excellent filler dispersion throughout the polyester matrix and much favorable interactions between CaSO₄ particles and ester functions of PLA chains as evidenced by the use of predictive mathematical models for composite mechanical properties and SEM-BSE imaging of fractured surfaces.     

PET/PLA共混物相容性和结晶性能的研究

研究了相容剂钛酸四丁酯[Ti(OBu)4]含量、聚乳酸(PLA)含量对聚对苯二甲酸乙二醇酯(PET)/PLA共混物相容性的影响,探讨了共混物的熔融和结晶行为,并对其结晶形貌进行了观察。结果表明,Ti(OBu)4含量为PLA的4%(质量分数,下同)时,PET/PLA共混物的相容性良好,但当PLA含量超过30%时,共混物出现相分离;PLA的加入使PET的结晶峰变窄,结晶速率增加,且结晶峰温度向高温方向移动;PLA的加入使PET的晶粒尺寸大幅减小,晶粒数目大幅增加,结晶更加完善。     

Super soft elastomers as ionic conductors

Melts of linear brush polymers with PEO side chains attached at each repeat unit of the backbones have been doped with CF₃SO₃⁻Li⁺. Mechanical properties and ionic conductivity of such systems have been analyzed using mechanical and dielectric spectroscopies. Mechanical spectra indicated a presence of super soft states for samples with long backbones or for systems which have been slightly cross-linked (G′<10⁴ Pa). In the case of the polymer with longer crystallizing PEO side chains (MW_av=1100 g/mol), the ionic conductivity reaching the 10⁻³ S/cm level at the optimum CF₃SO₃⁻Li⁺ concentration (EO/Li⁺=10:1) have been detected at temperatures not far above the room temperature. The presence of lithium ions suppresses completely the crystallization of PEO side chains.     

PPC/PBAT生物降解材料热性能和力学性能的研究

采用聚对苯二甲酸丁二醇酯-己二酸丁二醇酯(PBAT)对聚甲基乙撑碳酸酯(PPC)进行共混改性,对共混物进行了性能分析,并对PPC纯料与纤维素进行受控堆肥条件下最终需氧生物分解和崩解能力测试。结果表明:相同时间内PPC的生物分解速率要低于纤维素的生物分解速率;120 d内纤维素最大生物分解率为90%,PPC最大生物分解率约为63%;当PBAT的加入量为20%时,PPC的玻璃化转变温度提高3.55℃,失重率5%、50%和90%时的温度分别最高提高3.61℃、42.73℃和70.21℃;当PBAT含量为40%时,共混片材的拉伸强度最高提高了236.4%。     

Morphological variations in PMMA-modified epoxy mixtures by PEO addition

Thermoplastic epoxy blends are successfully used commercially. The thermoplastic may serve as a toughening agent although other properties may also be improved. In the present study, microscopy and mechanical testing techniques were used to study morphology and ultimate properties of ternary epoxy/Poly(methyl methacrylate) (PMMA)-Poly(ethylene oxide) (PEO) blends. PEO is functioning like a compatibilizer by which the morphology of the resulting polymer mixture may be changed dramatically by only small amounts of PEO. Whilst stiffness was controled by the corresponding matrix of the ternary mixture, both strength and fracture toughness were a function of the defined morphology. However, the most efficient toughening agent was PMMA, in particular when present as a co-continuous PMMA-rich phase within the epoxy-rich matrix.     

ACR增韧聚碳酸酯/聚乳酸合金的制备与性能研究

以核壳结构的丙烯酸酯类树脂(ACR)作为增韧剂,对聚碳酸酯(PC/)聚乳(酸PLA)合金进行增韧改性,研究了ACR用量对合金力学性能、热性能和微观形态的影响。结果表明:加入一定用量的ACR,合金的冲击强度大幅度提高,而其他力学性能影响较小;合金比例为PC/PLA=90/10时,二者的相容性良好,体系只有一个玻璃化温度;ACR的用量对合金的微观形态有一定的影响。     

Miscibility of chitosan/poly(ethylene oxide) blends and effect of doping alkali and alkali earth metal ions on chitosan/PEO interaction

The miscibility of Chitosan (CS) and poly(ethylene oxide) (PEO) in their blends and the effect of K⁺ and Ca²⁺ doping on the CS/PEO interaction have been investigated in this work. CS and PEO appeared to be miscible and the DSC analysis suggested the Flory-Huggins interaction parameter χ_AB to be −0.21. Doping of K⁺ and Ca²⁺ into the CS/PEO blend matrix enhanced the cooperative interaction between CS and PEO and this enhancement was larger for Ca²⁺ than for K⁺. The difference between Ca²⁺ and K⁺ possibly reflects a stronger multi-valence interaction of Ca²⁺ with the amino and hydroxyl groups of CS as well as the ether groups of PEO to form a stable CS/Ca²⁺/PEO complex and a less significant interaction of K⁺, as suggested by DSC, WAXD and FTIR results. MD simulations clearly indicated the correlation between the dynamic behavior and the interaction of K⁺ and Ca²⁺ in the CS/PEO blend matrix.     

改性剂对聚乳酸/淀粉性能影响的研究进展

针对聚乳酸(PLA)与淀粉直接混合造成力学性能和相容性变差的问题,介绍了添加改性剂对PLA/淀粉热学、力学性能和降解性能的影响,并对PLA/淀粉共混复合材料的发展前景进行展望.