制备方法对聚乳酸/聚丙撑碳酸酯性能的影响

通过熔融共混法和溶液浇注法制备了聚丙撑碳酸酯(PPC)与聚乳酸(PLA)的共混物。采用转矩流变仪、差示扫描量热仪、扫描电子显微镜、紫外可见近红外分光光度计等对共混物进行了表征,研究了共混方法对材料性能的影响。实验结果表明:PLA/PPC为部分相容性共混物,常温下放置体系会发生物理老化;PPC的加入使共混物的水蒸气阻隔性提高,随着温度的升高,共混物的水蒸气阻隔性明显降低,特别是PPC含量多的组分;PPC的加入还使共混物拉伸强度和杨氏模量降低,断裂伸长率提高。熔融共混会造成PPC和PLA的降解,降低体系黏度;相对于溶液浇注制备的共混物,其断裂伸长率较低,水蒸气阻隔性较好。     

聚乳酸/聚丁二酸丁二醇酯/二氧化碳基热塑性聚氨酯三元薄膜的制备与性能研究

用熔融共混法和挤出吹膜工艺制备了聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)/二氧化碳基热塑性聚氨酯(PPCU)薄膜。用差示扫描量热仪(DSC)、力学测试、流变测试和接触角分别详细研究了PLA/PBS/PPCU共混体系的结晶性能、力学性能、流变学特性和亲水性。DSC结果分析表明PLA与PBS的结晶可互相抑制,共混体系总结晶度下降,有利于薄膜的韧性提高。力学结果表明PPCU对PLA改性效果好,显著提高其力学性能。而PBS的加入进一步改善了PLA的柔韧性,断裂伸长率更高,杨氏模量下降显著。PBS的加入使体系黏度降低,增加流动性。PBS对改善共混薄膜亲水性有一定作用。     

马来酸酐接枝聚乳酸增容聚碳酸亚丙酯/聚乳酸共混体系的结构与性能研究

采用熔融接枝技术将马来酸酐(MAH)接枝到聚乳酸(PLA)上,制备不同MAH含量的PLA-g-MAH接枝共聚物,将聚碳酸亚丙酯(PPC)、PLA、PLA-g-MAH熔融共混,制备PPC/PLA/PLA-g-MAH共混物,分析接枝物中MAH含量对PPC/PLA/PLA-g-MAH共混体系的热学性能以及力学性能的影响。结果表明:PLA-g-MAH可以改善PPC与PLA二者的相容性,使PLA在降温过程中更容易结晶。引入接枝物后,共混物的起始分解温度及完全分解温度分别提高30℃和60℃。共混物的力学性能随着接枝物中MAH含量的增加呈现先增加后减小的趋势,当MAH的加入量为3%,共混体系力学性能最佳,冲击断面塑性形变程度更加显著,呈现褶皱状韧性断裂特征,拉伸强度达到42.8 MPa,断裂伸长率为120%左右,同时冲击强度最大。     

聚丁二酸丁二醇酯与聚乳酸共混型全生物降解材料的结构和性能研究

通过机械共混法,使聚丁二酸丁二醇酯(PBS)、聚乳酸(PLA)熔融共混,制备了一种完全生物降解塑料。用红外光谱(FTIR)法、DSC(DifferentialScanningCalorimetry)法、扫描电镜法(SEM)及力学测试等手段研究了不同组分配比情况下共混物的结构、热性能以及力学性能变化。并研究了聚丙撑碳酸亚丙酯(PPC)的加入对共混体系性能的影响。结果表明:随着PBS含量的增加,PBS/PLA共混体系的拉伸强度降低不多,而断裂伸长率显著提高。而PPC的加入能够提高共混体系的相容性并显著提高体系的韧性。     

聚碳酸亚丙酯与聚乳酸共混物性能及热分解动力学分析

采用溶液浇铸法制备了聚碳酸亚丙酯(PPC)/聚乳酸(PLA)共混物,通过力学性能测试、衰减全反射红外光谱分析、差示扫描量热分析和热失重分析研究了共混物的性能,并对共混物进行了热分解动力学研究。结果表明,随着PLA含量的增加,共混物的拉伸强度增大,断裂伸长率减小,PPC/PLA共混物的力学性能得到改善;随着PLA的含量从10%(质量分数,下同)增加到90%,共混物热失重10%所对应的温度(T-10%)从255℃逐渐增加到281℃,当PLA的含量分别为10%、50%和90%时,最大速率失重温度比纯PPC分别提高了3.45、15.51和41.58℃;采用Coats-Redfern法得出,PLA的加入能提高PPC的活化能,其中PLA含量为30%和50%时,共混物的活化能比纯PPC分别提高了12.72%和40.68%,说明PLA改善了PPC的热稳定性。     

聚碳酸亚丙酯-聚乳酸共混熔纺纤维的制备与性能

以乙烯-马来酸酐共聚物(ZeMac)作为反应性相容剂,利用熔融纺丝法制备了聚碳酸亚丙酯(PPC)-聚乳酸(PLA)共混纤维。通过傅里叶变换红外光谱仪、热重分析仪、差示扫描量热分析仪、纤维强伸度仪等分别研究了共混纤维的分子结构、热稳定性、相容性及力学性能。结果表明:PLA的引入较大地提高了PPC的力学性能,加入少量的ZeMac可以有效地改善PPC的热稳定性,同时也能够提高共混体系的相容性。当PPC-PLA与PPC-PLA-ZeMac体系组分质量比分别为70/30和70/30/0.7时,其抗拉强度分别为11.23 MPa和20.83 MPa,较未改性的PPC分别提高了6.5倍和12.1倍,同时还能保持较高的断裂伸长率。该项研究为完全可生物降解PPC熔融共混纤维的工业化提供了可能性。     

PLA-g-GMA的制备及其对PLA/PPC共混体系性能的影响

采用双螺杆挤出机将甲基丙烯酸缩水甘油酯(GMA)接枝到聚乳酸(PLA)上,而后将接枝产物(PLA-g-GMA)与聚乳酸(PLA)、聚碳酸亚丙酯(PPC)反应性共混,考察了接枝物中GMA加入量变化对PLA/PPC/PLA-g-GMA共混体系的力学性能、热稳定性能的影响,并对共混体系的断裂机理进行了研究。结果表明,PLA-g-GMA的引入能够在一定程度上改善PLA与PPC的相容性。随着接枝物中GMA加入量的增加,共混物的冲击强度、断裂伸长率及拉伸强度均呈现出先升高后降低的趋势,并在接枝物中GMA加入量为3%时达到最大值。扫描电镜结果显示,PLA-g-GMA引入后共混物的韧性断裂特征越发显著,其冲击断裂方式由脆性断裂过渡为韧性断裂。热失重分析结果显示,加入PLA-g-GMA后共混物的起始分解温度和完全分解温度均有一定程度的提高。     

PLA/PPC/OMMT纳米复合材料的结构与性能研究

采用双螺杆挤出机制备了聚乳酸（PLA）/聚碳酸亚丙酯（PPC）共混物和PLA/PPC/有机改性蒙脱土（OMMT）纳米复合材料,采用偏光显微镜、差示扫描量热仪和力学性能试验机等对共混物和纳米复合材料的相态结构、熔融与结晶行为和力学性能等进行了研究。结果表明,在PPC含量低于30 %时,随着PPC含量的增加,PLA/PPC和PLA/PPC/OMMT体系中PLA的玻璃化转变温度（Tg）均降低,在PPC含量为50 %时出现了明显的相分离;随着PPC含量的增加,PLA/PPC的冲击强度增大;OMMT的含量小于1.5 %时,PLA/PPC/OMMT体系的结晶度、拉伸强度、断裂伸长率和冲击强度均随OMMT含量的增加而增大。     

PLA/PBAT/二(噁)唑啉共混物的性能

以2,2-(1,3-亚苯基)-二(噁)唑啉(BOZ)为增容剂,采用熔融共混的方法制备聚乳酸(PLA)/聚己二酸-对苯二甲酸丁二酯(PBAT)/BOZ共混物,研究该增容剂对共混体系的力学性能、微观形态、结晶性能的影响.结果表明:少量的增容剂能提高PLA和PBAT的界面粘合力,改善PLA/PBAT共混体系的力学性能.在不同的PBAT含量下,PLA/PBAT/BOZ的力学性能均高于PLA/PBAT.由TEM可以看出,BOZ的加入使PBAT的分散相尺寸明显减小,分散更均匀.DSC结果表明:BOZ的加入使共混物中PLA的结晶速率和结晶度下降.     

PLA/PBAT/二唑啉共混物的性能

以2,2-(1,3-亚苯基)-二唑啉(BOZ)为增容剂,采用熔融共混的方法制备聚乳酸(PLA)/聚己二酸-对苯二甲酸丁二酯(PBAT)/BOZ共混物,研究该增容剂对共混体系的力学性能、微观形态、结晶性能的影响。结果表明:少量的增容剂能提高PLA和PBAT的界面粘合力,改善PLA/PBAT共混体系的力学性能。在不同的PBAT含量下,PLA/PBAT/BOZ的力学性能均高于PLA/PBAT。由TEM可以看出,BOZ的加入使PBAT的分散相尺寸明显减小,分散更均匀。DSC结果表明:BOZ的加入使共混物中PLA的结晶速率和结晶度下降。     

Study on the Crystallization Kinetic and Characterization of Poly(lactic acid) and Poly(vinyl alcohol) Blends

In this study, poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA) blends, with PLA/PVA mass ratios of 100/0, 90/10, 80/20, 70/30, 60/40, 50/50, and 40/60, were prepared by means of the melt blending method. The result of torque measurements and thermal gravimtric analysis tests showed that the addition of PLA can decrease the melt viscosity of PVA and that the second degradation step of PVA nearly disappeared for the PLA₈₀/PVA₂₀ blend. The absorbance peaks of the carbonyl group and the hydroxyl group in the Fourier transform infrared spectra of PLA/PVA blends had significant shifts to lower wave numbers, indicating that there were interactions between these two groups. Combined with the result of the differential scanning calorimetry curves, this interaction would be favorable for improving miscibility. The X-ray diffraction patterns and the polarized light microscope (PLM) micrographs showed that PVA can serve as a nucleating agent to promote the crystallization of PLA in PLA/PVA blends. Moreover, the PLA₈₀/PVA₂₀ blend gave the highest growth rate of PLA spherulite.     

Study on the Crystallization,Miscibility, Morphology,Properties of Poly(lactic acid)/Poly(ε-caprolactone) Blends

A series of blends of poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) with different mass ratio were prepared by means of the melt blending method to study their crystallization, miscibility, morphology, and thermal and mechanical properties. The result of DSC tests showed that the melting temperatures of PLA and PCL shifted toward each other, and that the largest shift appeared at the PLA₇₀PCL₃₀ blend. This result reveals that the PLA₇₀PCL₃₀ blend gives the strongest interaction intensity among the blends. Combined the result of dynamic mechanical analysis and SEM morphologies, it was found that PLA and PCL form a partial miscible blend, in which an amount of amorphous PCL (amorphous PLA) is dissolved in the PLA-rich phase (PCL-rich phase), leading to a depression of the T_g. value. The polarized optical micrographs showed that PCL can serve as a nucleating agent to promote PLA crystallization in the PLA/PCL blend. Moreover, the PLA₇₀PCL₃₀ blend gave the largest growth rate of PLA spherulite. Finally, the mechanical property of PLA/PCL blends indicated that PLA can easily be tuned from rigid to ductile by the addition of PCL.     

The effect of MBS on the heat resistant,mechanical properties,thermal behavior and rheological properties of PLA/EVOH blend

This work focuses on improve the mechanical properties of poly(lactic acid)/poly(ethylene-co-vinyl alcohol) (PLA/EVOH) blend and simultaneously remained a high Vicat softening temperature (VST) using appropriate contents of methyl methacrylate–butadiene–styrene copolymer (MBS) via simple melt blending. The effects of MBS on the heat resistant, mechanical properties, thermal properties and rheological behavior were examined in detail with various techniques. The VST of neat PLA significantly increased to 159 °C from 66.8 °C after blending with 50 wt% EVOH. However, the VST was gradually decreased with increasing MBS content but were still much higher than that of neat PLA. On the basis of the tensile and impact tests results, PLA/EVOH/MBS blends showed a considerably higher elongation at break and impact strength. For all PLA/EVOH/MBS blends, the thermal stability was increased compared than that of PLA/EVOH blend without MBS. With increasing MBS content, the complex viscosity and storage modulus of PLA/EVOH blend increased, especially at low frequencies, indicating that MBS enhanced the chain entanglement in the PLA/EVOH matrix. In addition, the results Han curves and Cole–Cole plots indicated that the relaxation time was increased when MBS was added.     

Study on the effect of dispersion phase morphology on porous structure of poly (lactic acid)/poly (ethylene terephthalate glycol-modified) blending foams

A methodology for blending foam of poly (lactic acid) (PLA)/poly (ethylene terephthalate glycol-modified) (PETG) was proposed. PLA/PETG blends were prepared through a melt blending method, using multiple functionality epoxide as reactive compatibilizer. The effects of blending ratio and compatibilizer content on the dispersion morphology, molecular structure, mechanical properties, and rheological behavior of PLA/PETG blends were studied. Then PLA/PETG blends were foamed using supercritical CO₂ as physical blowing agent, and their porous structure, pore size, as well as pore density were investigated. The results showed that the mechanical properties and rheological parameters such as melt strength and melt elasticity, as well as the porous structure of the foams dispersion morphology of PLA/PETG blends were affected strongly. The melt elasticity of PLA/PETG blends increased with increasing compatibilizer content. Dispersion phase morphology of PLA/PETG blends also had a significant effect on the pore density of all the samples. The results indicated that homogeneous and finer porous morphology of PLA/PETG foams with high expansion ratio could be achieved with a proper content of compatibilizer in the blends.     

聚乳酸/聚丁二酸丁二醇酯共混物的研究

通过熔融共混制备了聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)共混物,采用扫描电子显微镜、差示扫描量热仪、旋转流变仪对其相容性、热性能和黏度等进行了研究,并研究了PBS的加入对PLA力学性能的影响。结果表明,PLA和PBS之间是部分相容的,PBS的少量添加并不影响PLA的拉伸强度,且其冲击强度随着PBS含量的增加呈先上升后下降的趋势,当PBS含量为10份时,共混物的冲击强度最好;与纯PLA相比,共混物的黏度有所增加,且随着PBS含量的增加,共混物的黏度逐渐增大;PBS的添加起到异相成核作用,促进了PLA的结晶。     

Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends

Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers     

Effect of chain extrender on the compatibility,mechanical and gas barrier properties of poly(butylene adipate-co-terephthalate)/poly(propylene carbonate) bio-composites

Bio-composites consisting of poly(butylene adipate-co-terephthalate) (PBAT), poly(propylene carbonate) (PPC) and epoxy chain extender ADR 4468 were fabricated via melt blending using a torque rheometer. The relationship of the torque, melt viscosity, and molecular weight of the bio-composites was established via polymeric liquid theory to estimate the real-time chain extension reaction rate under different ADR contents. At the meantime, rheological behavior, thermal and mechanical properties, morphologies, gas barrier properties of the PBAT/PPC/ADR bio-composites were systematically characterized. The corresponding results revealed that the water vapor transmission rate (WVTR) reduced by 50% under 30 phr (parts per hundreds of resin) PPC content. The addition of ADR is beneficial to improve the mechanical properties, thermal stability and phase dispersion of PBAT/PPC without affecting the water barrier property. With 3 phr ADR, the tensile stress and elongation at break were increased from 19.5 MPa and 1184% to 26.9 MPa and 1443%, respectively. In addition, the data of the torque rheometer revealed that the chain extension reaction rate and the melt viscosity was increased with the increasing ADR content, but the reaction rate was reduced with the excessive viscosity.     

PPC/PDAP共混膜的制备和性能

将过氧化二异丙苯(DCP)置于特定温度下,引发邻苯二甲酸二烯丙酯(DAP)在聚碳酸亚丙酯(PPC)溶液中聚合,制备得到聚碳酸亚丙酯/聚邻苯二甲酸二烯丙酯(PPC/PDAP)共混膜。采用红外光谱仪(FTIR)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)、热重分析仪(TGA)、万能试验机和水蒸气透过率测试仪对共混膜的红外吸收、结晶性、热、力学和阻隔性能进行了表征。结果表明,通过DAP的聚合,提高了PPC的结晶性,使PDAP在PPC基体中形成交联网络,提高了共混膜的热、力学和阻隔性能。相比纯PPC,当DAP含量为20%时,共混膜的玻璃化转变温度和拉伸强度分别提高了5.3℃和266%;当DAP含量为40%时,共混膜的失重5%热分解温度提高了50.9℃,透湿系数下降了25%,因此,阻隔性能得到了提升。     

Crystallization and phase separation in blends of high stereoregular poly(lactide) with poly(ethylene glycol)

The effect of cooling rate on crystallization and subsequent aging of high stereoregular poly(lactide) (PLA) blended with poly(ethylene glycol) (PEG) was studied by thermal analysis and by direct observation of the solid state structure with atomic force microscopy (AFM). Blending with PEG accelerated crystallization of PLA. When a PLA/PEG 70/30 (wt/wt) blend was slowly cooled from the melt, PLA crystallized first as large spherulites followed by crystallization of PEG. The extent of PLA crystallization depended on the cooling rate, however, for a given blend composition the PEG crystallinity was proportional to PLA crystallinity. The partially crystallized blend obtained with a cooling rate of 30 °C min⁻¹ consisted of large spherulites dispersed in a homogeneous matrix. The blend was not stable at ambient temperature. With time, epitaxial crystallization of PEG on the edges of the spherulites depleted the surrounding region of PEG, which created a vitrified region surrounding the spherulites. Further from the spherulites, the homogeneous amorphous phase underwent phase separation with formation of a more rigid PLA-rich phase and a less-rigid PEG-rich phase. Decreasing the amount of PEG in the blend decreased the crystallization rate of PLA and increased the nucleation density. The amount of PLA crystallinity did not depend on blend composition, however, PEG crystallinity decreased to the extent that PEG did not crystallize in a PLA/PEG 90/10 (wt/wt) blend.