聚乳酸/聚癸二酸丙三醇酯共混物的形态及结晶性能

用SEM、DSC、光学解偏振光、POM及WAXD研究聚乳酸/聚癸二酸丙三醇酯(PLA/PGS)共混物的形态和等温结晶性能.结果表明:PLA与PGS发生了相分离,PLA分子链之间存在部分PGS.当<110℃等温结晶时PLA/PGS共混物的半结晶时间(t1/2)随PGS含量的增加而降低,其晶体尺寸较纯PLA大;当≥110℃等温结晶时,PLA/PGS共混物的t1/2随PGS含量的增加而变大,共混物的晶体尺寸明显增大,形成球晶.但当PGS的含量为20%并于120℃等温结晶时,晶体产生暗斑.PLA及PLA/PGS共混物的晶形都为α形.     

聚丁二酸丁二醇酯/聚乙二醇硬脂酸酯共混物非等温结晶行为

以聚丁二酸丁二醇酯（PBS）和聚乙二醇硬脂酸酯（PEOST）为原料,采用溶液共混法制备了PEOST质量分数分别为10%（POS-10）和30%（POS-30）的两种合金材料。通过差示扫描量热法（DSC）研究了合金材料的非等温结晶行为,用莫志深（Mo）法分析了PBS的非等温结晶动力学,采用Kissinger法和Friedman法计算PBS的结晶活化能,并用红外（FTIR）和偏光显微镜（POM）进行表征。研究结果表明：PBS先结晶形成结晶微区不利于PEOST结晶,而较高含量的PEOST有利于PBS的结晶。受PBS先结晶的影响,POS-10降温DSC曲线没有出现PEOST的结晶峰,而POS-30在低的降温速率情况下出现了PEOST双结晶峰;升温DSC曲线中两试样均出现了PEOST的熔融峰。在相同的冷却速率下,POS-30的PEOST熔融温度（T_m）和熔融焓（△H_m）大于POS-10;POS-30的PBS结晶峰温度（T_p）、结晶焓（△H_c）大于POS-10,而结晶半峰宽（D）值更小;但两者的T_m和△H_m相当。随冷却速率的增加,PBS的D值增大,而PEOST的D值却降低;冷却速率的增加对PBS的T_m值影响不大,但使PEOST的T_m略有减小。Mo法适合用于共混物中PBS的非等温结晶动力学分析。POS-30的PBS绝对值结晶活化能要大于POS-10。POS-30在红外光谱谱图中出现了PEOST结晶的红外响应峰（1109cm^-1和841cm^-1）而POS-10没有。     

可生物降解聚癸二酸丙三醇酯弹性体的组成及结晶性能

在不同摩尔比条件下,利用丙三醇和癸二酸通过熔融共缩聚反应方法合成了可生物降解的聚癸二酸丙三醇酯弹性体(PGS)。通过溶胀实验、X射线衍射分析及差示扫描量热分析对其组成和结晶性能进行了表征。结果表明,PGS是一种由溶胶和凝胶组成的低交联度聚酯,其中溶胶含量大于75%;PGS的玻璃化转变温度低于-25℃;当癸二酸用量增加时,PGS中存在着结晶,具有以非晶相为软区、晶相为硬区的微观相分离结构。     

PET/PBT共混物非等温结晶行为的研究

采用差示扫描量热法(DSC)研究了聚对苯二甲酸乙二醇酯/聚对苯二甲酸丁二醇酯(PET/PBT)共混物的非等温结晶行为;研究了冷却速率对PET/PBT滑/石粉(Talc)成/核剂(P250)共混物结晶行为的影响。对其数据分别采用Jeziorny法、Ozawa法和Mo法进行处理。结果表明:PET/PBT共混物在加入滑石粉后相对结晶度(Xc)有所下降,但是结晶速率提高;PET/PBT/Talc体系单独引入成核剂体系效果更优;PET/PBT/Talc/P250体系随降温速率的增大,结晶度下降,结晶速率加快;Jeziorny法和Mo法处理非等温结晶过程比较理想,Ozawa法则具有一定的局限性。     

聚乳酸/聚(已二酸-对苯二甲酸丁二酯)共混物的非等温结晶动力学

采用熔融挤出法制备了聚乳酸/聚(已二酸-对苯二甲酸丁二酯)共混物。利用差示扫描量热仪研究了聚乳酸及其共混体系的非等温结晶过程。用经Jeziorny修正的Avrami方程和Mo法对其非等温结晶动力学进行了分析。结果表明:Avrami方程和Mo法都适用于处理聚乳酸及其共混体系的非等温结晶过程,共混物的结晶速率大于聚乳酸的结晶速率。此外,用Huffman-Lauritzen理论计算了非等温结晶的结晶活化能,发现共混体系的结晶活化能绝对值小于聚乳酸。     

聚癸二酸丙三醇丁二醇酯/聚乳酸共混物的制备和性能表征

以1,4-丁二醇(B),丙三醇(G)和癸二酸(S)通过熔融缩聚合成新型聚酯改性剂聚癸二酸丙三醇丁二醇酯(PGBS),并制备了PGBS/PLA共混物.用FTIR、1H-NMR、DSC、SEM分别表征了PGBS的分子结构及共混物的热性能、相形貌,同时对其力学性能和亲水性进行研究.结果表明:PGBS和PLA是部分相容的;G含量为0时,PGBS对PLA的结晶促进作用明显.随G含量增加,PGBS能很好地提高PLA的断裂伸长率和冲击强度;共混物的亲水性亦随G含量增加有明显提高.     

碳纳米管/聚乳酸复合材料非等温结晶动力学

研究了聚乳酸(PLA)与多壁碳纳米管(MWNTs)/PLA复合材料的非等温结晶动力学。利用硅烷偶联剂KH-550改性碳纳米管,并用溶液共混法制备MWNTs/PLA复合材料。利用DSC研究了材料的结晶过程,所得的降温曲线表明基体中的碳纳米管可以提高材料的结晶温度范围和结晶放热焓。采用Jeziorny法和Mo法研究了PLA与MWNTs/PLA复合材料的非等温结晶动力学,结果表明,适量的碳纳米管有效地起到了成核剂的作用,提高了材料的结晶速率。     

锦纶6/聚偏二氟乙烯共混纤维的非等温结晶行为

采用差示扫描量热法(DSC)研究了熔融纺丝法制备的锦纶6(PA6)/聚偏二氟乙烯(PVDF)共混纤维的非等温结晶行为,并利用修正Avrami方程的Jeziorny法和R-t法对其结晶动力学进行分析。结果表明,由于PVDF的黏度大,且PVDF中的氟原子能与PA6的酰胺键形成氢键,阻碍了PA6分子链在结晶过程中的运动,导致共混纤维的结晶温度和结晶速率比纯PA6纤维低,半结晶时间比PA6大,且随着PVDF含量的增加,其变化更为明显。     

增韧改性聚对苯二甲酸丁二酯/聚碳酸酯共混物非等温结晶动力学与力学性能

The polybutylene terephthalate (PBT）/ polycarbonate (PC）blends modified by toughening agent（S-2001）consisting of methyl methacrylate, styrene and silicone were prepared via melt blending.The non-isothermal crystallization kinetics of the blends were investigated by scanning calorimetry (DSC）at different cooling rate of 5℃·min^-1,10℃·min^-1,15℃·min^-1, and the data were analyzed by using modified Avrami theories of the Jeziorny method.The influence of toughening agent相似文献   

PET/PEA共混物的非等温结晶及晶态结构

采用升、降温DSC和广角X射线衍射等测试手段研究了不同共混比的PET/液晶共聚酯酰胺(PEA)机械共混物、溶液共混物的非等混结晶和晶态结构。结果表明PEA在20％的范围内能起到成核剂的作用,促进PET结晶,并且当PEA的加入量为2.5％时,PET最易结晶;共混物中PET的晶态结构受PEA的影响不大,PEA的引入使共混物各晶面间距增大,共混物的结晶度呈现先上升而后降低之趋势。     

Non-Isothermal Crystallization of High-Impact Polystyrene/Poly(Phenylene Sulfide) Blends

The morphology of isothermally crystallized poly(phenylene sulfide) (PPS) and a blend combining it with high-impact polystyrene (HIPS) were observed through a polarized optical microscope equipped with a CSS450 hot-stage. The crystalline superstructure of PPS is mainly spherulite, and it was found that the presence of HIPS has little influence on the morphology of PPS, but decreases the nucleation rate of PPS. The effect of HIPS on the non-isothermal crystallization of PPS was investigated by differential scanning calorimetry (DSC). The maximum and onset crystallization temperatures for the HIPS/PPS blend were about 10°C lower than those of neat PPS, which indicates that the crystallization of PPS was retarded by HIPS. The Ozawa model was used to analyze the non-isothermal crystallization kinetics of PPS and its blends. The Avrami exponent values of neat PPS were higher than those of its blend, which shows that the presence of HIPS changed both the nucleation rate and the crystallization rate of PPS.     

PET/PTT共混聚酯的等温结晶行为

使用差示扫描量热仪(DSC)研究不同比例的PET/P1T共混聚酯在205℃的等温结晶行为,并使用Avrami方程对其等温结晶过程进行研究.结晶半周期t1/2,总结晶速率常数k和Avrami指数n的变化表明:在共混体系中,对于PET和PTT而言,另一组分的加入都会对结晶产生阻碍作用,PET与P1T相互影响成核与晶体生长机理.     

Non-Isothermal Crystallization of Poly(Vinylidenefluoride)/Hollow Glass Microspheres Composites

The Poly(vinylidene fluoride)/Hollow glass microspheres(PVDF/HGMs) composites were prepared by the method of solution blending. The non-isothermal crystallization of the PVDF and its composites were investigated with a differential scanning calorimeter (DSC). The results showed that the crystallization peaks shifted to a lower temperature and became wider with an increasing cooling rate. The HGMs caused to increase in crystallization temperature and initial crystallization temperature. In addition, the Jeziorny and the Mo methods were used to analyze the non-isothermal crystallization kinetics. The results showed that the crystallization rate rose with the cooling rate rising, however, the HGMs decreased the crystallization rates of the PVDF.     

Toughening Behavior of Poly(L-Lactic Acid)/Poly(D-Lactic Acid) Asymmetric Blends

The L-configured poly(lactic acid) has exhibited vast appeal in the past decades. However, most previous researches reveal that L-configured poly(lactic acid) exhibits fragile behavior, which limits its applications. Present work clarified that the toughness of poly(lactic acid) depended on the content of crystallites and rigid component incorporated into the specimens. The elongation at break was remarkably high in the L-configured poly(lactic acid)/D-configured poly(lactic acid) with a small amount of D-configured poly(lactic acid) (≤15%). The stretching led to orientation of crystals and amorphous molecular chains and segments. The crystals did not vary, while the amorphous molecular chains transited to mesophase during stretching, and this mesophase formed homocrystallites during heating.     

Non-isothermal Crystallization Behavior of Poly(ethylene terephthalate)/Poly(trimethylene terephthalate) Blends

Summary Non-isothermal crystallization behavior of Poly(ethylene terephthalate)/Poly(trimethylene terephthalate) blends was investigated by XRD and DSC. By XRD spectra analysis, it could be concluded that PET and PTT crystals coexisted. They did not form the cocrystals due to different chemical structures. The Avrami equations modified by Jeziorny and Ziabicki’s kinetic crystallizability analysis were employed to describe the non-isothermal crystallization process of PET/PTT blends. The results suggested that the entanglement of the two polymer chains decrease the crystallizability of PET and PTT in blend. The crystallization activation energies of the blend evaluated by the Friedman method also indicated that the presence of two components in the blends hinders the crystallization process of both components.     

Structure,Performance and Crystallization Behavior of Poly (Lactic Acid)/Humic Acid Amide Composites

Humic acid amide (HA-amide) was prepared by amidation of HA and dodecylamine (DDA) with carbonyl diimidazole (CDI) as coupling reagent. Furthermore, HA-amide was added to poly (lactic acid) (PLA) as a nucleating agent to prepare poly (lactic acid)/humic acid amide composites (PLA/HA-amide) by melt blending. The structure and performance of PLA/HA-amide composites were investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheological analysis. Non-isothermal crystallization kinetics showed the HA-amide enhanced the crystallization rate of PLA. The results of crystallization behavior of PLA/HA-amide composites showed that HA-amide was an efficient nucleating agent of PLA.     

Study on Bulk and Surface Properties of Poly(Lactic Acid)/Fluorinated Polymer Blends

The easy hydrolysis of poly(lactic acid) (PLA) leads to very poor mechanical stability. In order to improve water-resistance of PLA, fluorinated polymer has been chosen for its extremely low surface energy. Besides, n-butyl acrylate (BA) has been introduced into fluorinated polymer by copolymerizing BA with dodecafluorheptylmethylacrylate (FA) to enhance the compatibility of fluorinated polymer and PLA. The bulk and surface properties of PLA/fluorinated polymers blends have been studied. The results show that the compatibility of PLA and fluorinate polymers has been improved by BA and, more importantly, the hydrophobicity of PLA has increased obviously by blending with the fluorinate polymers.     

Spherulitic Morphology and Crystallization Kinetics of Poly(vinylidene fluoride)/Poly(vinyl acetate) Blends

Spherulitic morphology and crystallization kinetics of the blends of poly(vinylidene fluoride) (PVDF) and poly(vinyl acetate) (PVAc) prepared by solution casting films have been investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results suggested that PVAc was mainly segregated into the interlamellar and/or interfibrillar regions due to the volume-filling spherulitic morphology observed. As for the results of crystallization kinetics, it was found that both the PVDF spherulitic growth rate (G ^PVDF) and the overall crystallization rate constant (k _n ) were depressed with either the addition of PVAc component or the increase of crystallization temperature (T _c). The kinetics retardation was attributed to the decrease in PVDF molecular mobility and dilution of PVDF concentration due to the addition of PVAc, which has a higher glass transition temperature (T _g).     

Heat Resistant and Mechanical Properties of Biodegradable Poly(Lactic Acid)/Poly(Butylene Succinate) Blends Crosslinked by Polyaryl Polymethylene Isocyanate

This work focus on improving the heat resistant and mechanical properties of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) blends using appropriate contents of polyaryl polymethylene isocyanate (PAPI). Some crosslinked structures were formed according to the gel fraction and rheological results, and the crosslinked structures played the role of nucleation site for the blends. And the Vicat softening temperature of the blends gradually increased with increasing PAPI content. Moreover, the addition of PAPI in the PLA/PBS blends produced a few PLA-PBS copolymers which acted as a compatibilizer and enhanced the interfacial adhesion. Thus, the mechanical properties of PLA were significantly improved.     

Crystallization,Morphological, and Mechanical Response of Poly(Lactic Acid)/Lignin-Based Biodegradable Composites

Green/bio-based composites of poly(lactic acid) and lignin were prepared by melt blending in a twin-screw extruder. Thermal and mechanical properties, phase interaction, and morphology of the composites have been investigated. Fourier transform infrared studies elucidated the existence of intermolecular hydrogen bonding between poly(lactic acid) and lignin. Scanning electron microscopy studies revealed an extent of diffused phase boundaries between poly(lactic acid) and lignin which also indicated significant interaction between them. Tensile properties showed significant increase over neat poly(lactic acid) with lignin loading (0–0.28 volume fraction) which further justified using theoretical models. Izod impact strength decreased with lignin content.