外场作用对PBS及嵌段共聚物PBS-b-PEG结晶形态的影响

采用偏光显微镜对聚丁二酸丁二醇酯(PBS)及聚酯嵌段共聚物聚丁二酸丁二醇酯-b-聚乙二醇(PBS-b-PEG)在不同外场环境下的结晶形态进行研究。结果表明:在等温结晶过程中,PBS及PBS-b-PEG的球晶尺寸及形貌同结晶温度和时间密切相关,PBS在90℃等温结晶2 h后可形成明显的环带球晶形态;PBS及PBS-b-PEG在水环境下等温结晶,水起到成核剂的作用,使球晶尺寸细化,球晶形貌发生改变;超声振动作用具有使PBS球晶尺寸细化作用,而对PBS-b-PEG结晶影响较小。     

PBS/PHAs的熔融行为和非等温结晶动力学

用示差扫描量热仪测定了聚羟基丁酸酯(PHAs)/聚丁二酸丁二醇酯(PBS)共混体系的熔融和非等温结晶动力学。结果发现:PHAs和PBS之间存在着相互作用。用Jeziorny方程对共混体系的非等温结晶动力学进行了研究,说明PHAs的加入对PBS的结晶动力学参数影响不大,PHAs的加入没有起到异相成核的作用,而是使PBS的结晶生长更加完善。用Kissinger方程计算了体系的结晶活化能,发现PHAs的加入使结晶活化能先升高后降低。     

PBS-PTMO嵌段共聚物的合成及其结晶动力学北大核心

以丁二酸、丁二醇以及聚四氢呋喃醚(PTMO)为原料制备了w(PTMO)为50%的可生物降解聚丁二酸丁二酯(PBS)-PTMO嵌段共聚物(记作PBSPTMO50)。采用核磁共振氢谱仪,凝胶渗透色谱仪对共聚物进行了表征,利用差示扫描量热仪研究了PBS硬段和软段的非等温结晶动力学。结果表明:PBSPTMO50的数均分子量和重均分子量分别为53 083,152 407,相对分子质量分布指数为2.87;PBSPTMO50有两个结晶峰;Ozawa方程能拟合PBS硬段的非等温结晶过程,但不适合PTMO软段;而莫志深方程能拟合PBS硬段和PTMO软段的非等温结晶过程。     

PBS-PTMO嵌段共聚物的合成及其结晶动力学

以丁二酸、丁二醇以及聚四氢呋喃醚(PTMO)为原料制备了w(PTMO)为50%的可生物降解聚丁二酸丁二酯(PBS)-PTMO嵌段共聚物(记作PBSPTMO50)。采用核磁共振氢谱仪,凝胶渗透色谱仪对共聚物进行了表征,利用差示扫描量热仪研究了PBS硬段和软段的非等温结晶动力学。结果表明:PBSPTMO50的数均分子量和重均分子量分别为53 083,152 407,相对分子质量分布指数为2.87;PBSPTMO50有两个结晶峰;Ozawa方程能拟合PBS硬段的非等温结晶过程,但不适合PTMO软段;而莫志深方程能拟合PBS硬段和PTMO软段的非等温结晶过程。     

硫酸钙晶须/PBS共混物等温结晶动力学研究

用差示扫描量热仪(DSC)测试了硫酸钙晶须/聚丁二酸丁二醇酯(PBS)共混物的等温结晶过程。采用Hoffm-weeks方程拟合的方法得到了4种配比的硫酸钙晶须/PBS共混物的平衡熔点,并根据实验数据拟合出描述硫酸钙晶须/PBS共混物等温结晶过程的Avrami方程。结果表明:共混物的平衡熔点随着硫酸钙晶须含量的提高而降低;硫酸钙晶须的加入,对PBS的成核机理和生长方式没有明显的影响;等温结晶温度不影响共混物的结晶机理,但会影响结晶速率,等温结晶温度越高,结晶速率越慢。     

共聚合改性可生物降解PBS

通过改变1,4-丁二醇(BD)与1,4-环己烷二甲醇(CHDM)的配比,将其与1,4-丁二酸(SA)进行熔融缩聚合制备可生物降解聚丁二酸丁二酯(PBS)及BD-SA-CHDM共聚物[P(BS-co-CHDM)]。表征了P(BS-coCHDM)的结构并研究了PBS及其共聚物的非等温结晶行为、晶体结构、结晶形态及力学性能。结果表明:Jeziorny法和莫志深法均可很好地描述P(BS-co-CHDM)的非等温结晶行为,与PBS相比,P(BS-co-CHDM)的结晶速率随CHDM含量的增加先增大再减小;P(BS-co-CHDM)的晶体结构与PBS相同,仍为单斜α晶,70℃等温结晶2 h后,球晶尺寸随P(BS-co-CHDM)中CHDM含量的增加而减小;y(CHDM)为20%时,P(BS-co-CHDM)的断裂拉伸应变达208.9%。     

生物可降解聚丁二酸/2,2-二甲基丁二酸丁二酯系列共聚物的合成与性能研究

合成了一系列聚丁二酸/2,2-二甲基丁二酸丁二酯共聚物(PBS-2M),利用DSC、1H-NMR和XRD等测试手段对共聚物组成、热力学性能、结晶性能、等温结晶行为进行了研究。结果表明：2,2-二甲基丁二酸共聚单元的引入显著改变了聚丁二酸丁二酯(PBS)的热力学性能,利用Hoffman-Week曲线得到的共聚物平衡熔点随共聚组分含量的增加显著降低,玻璃化转变温度亦有所降低,结晶熔点则符合无规共聚物的Flory方程。此外,利用Avrami方程对均聚物PBS以及共聚物PBS-2M-20分别进行了等温结晶行为研究。结果表明：共聚使结晶速率降低,PBS和PBS-2M-20的Avrami指数分别介于2.8~3.0和2.6~2.8之间,结晶方式为三维生长异相成核,XRD测试结果证明共聚不影响晶体结构。     

聚丁二酸丁二酯的结晶动力学研究

采用氯仿溶解聚丁二酸丁二酯（PBS）,然后利用甲醇逐级沉淀分离获得不同相对分子质量及其分布的PBS级分,分别采用差示扫描量热仪、广角X射线衍射仪、偏光显微镜等对不同级分PBS的等温和非等温结晶动力学、晶体形态及结构进行了系统研究。结果表明,随着相对分子质量的增加和相对分子质量分布的变宽,各级分的半结晶时间逐渐降低,结晶半峰宽逐渐变窄,结晶度逐渐增加;但各级分PBS的晶型和晶貌并未发生明显的转变。     

纳米氧化锌填充PBS复合材料性能的研究

采用硅烷偶联剂(KH-550)对纳米氧化锌进行了表面改性,通过熔融共混法制备了聚丁二酸丁二醇酯(PBS)/纳米氧化锌复合材料,利用扫描电子显微镜、热重分析仪、差示扫描量热仪等对复合材料的力学性能、热性能和非等温结晶性能进行了研究分析,并通过Ozawa-Flynn-Wall方法分析了复合材料的热降解行为。结果表明,纳米氧化锌能提高PBS的拉伸强度和弯曲强度,但降低了其冲击强度;改性后的纳米氧化锌可以提高其与PBS的界面相容性,并提高其在PBS基体中的分散性能,不同程度地提高了复合材料的力学性能;纳米氧化锌提高了PBS的结晶速率,降低了其热解反应活化能。     

PBS结晶影响因素的研究

采用偏光显微镜对聚丁二酸丁二醇酯(PBS)的结晶影响因素进行了研究。结果表明:在等温结晶时,PBS的最佳结晶温度随着分子量的增大而提高,当分子量增到一定值后,最佳结晶温度受分子量的影响很小。结晶温度一定时,PBS的晶体尺寸随着结晶时间的延长而增大。结晶时间一定时,PBS的晶体尺寸随着结晶温度的提高而先增大后减小。数均分子量为1×103、8×103、6×104、1×105的PBS最佳结晶温度分别为40℃~50℃、80℃、80℃、90℃。低分子量的PBS在较短的结晶时间内晶体尺寸就已较大,而高分子量的PBS在较长的时间内才能形成较大尺寸的晶体,数均分子量为8×103、6×104、1×105的PBS在最佳结晶温度形成较好结晶的时间分别为10min、20min、25min。     

Crystallization behavior of partially crosslinked poly(β‐hydroxyalkonates)/poly(butylene succinate) blends

Partially crosslinked poly(β‐hydroxybutyrate‐co‐β‐hydroxyvalerate)/poly(butylene succinate) (PHBV/PBS) and poly(β‐hydroxybutyrate)/poly(butylene succinate) (PHB/PBS) blends were prepared by melt compounding with dicumyl peroxide. The effect of partial crosslinking on crystallization of the PHBV/PBS and PHB/PBS blends was investigated systematically. Differential scanning calorimetry results showed that the overall crystallization rates of both PHBV and PBS in their blends were enhanced considerably by the partial crosslinking. Similar results were also detected in the PHB/PBS blends. The polarized optical microscope observation displayed that the nuclei density of PHBV was increased while the spherulitic morphology did not change much. Conversely, the PBS spherulites turned into cloud‐like morphology after the partial crosslinking which is a result of the decrease in spherulite size, the reduction in interspherulite distance and the interconnection of fine PBS domains. Wide angle X‐ray diffraction patterns confirmed the enhancement in crystallization of the PHBV/PBS blends after the partial crosslinking without modification on crystalline forms of the PHBV and PBS components. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41020.     

Nonisothermal crystallization behavior and mechanical properties of poly(butylene succinate)/silica nanocomposites

Silica nanoparticles and poly(butylene succinate) (PBS) nanocomposites were prepared by a melt‐blending process. The influence of silica nanoparticles on the nonisothermal crystallization behavior, crystal structure, and mechanical properties of the PBS/silica nanocomposites was investigated. The crystallization peak temperature of the PBS/silica nanocomposites was higher than that of neat PBS at various cooling rates. The half‐time of crystallization decreased with increasing silica loading; this indicated the nucleating role of silica nanoparticles. The nonisothermal crystallization data were analyzed by the Ozawa, Avrami, and Mo methods. The validity of kinetics models on the nonisothermal crystallization process of the PBS/silica nanocomposites is discussed. The approach developed by Mo successfully described the nonisothermal crystallization process of the PBS and its nanocomposites. A study of the nucleation activity revealed that the silica nanoparticles had a good nucleation effect on PBS. The crystallization activation energy calculated by Kissinger's method increased with increasing silica content. The modulus and yield strength were enhanced with the addition of silica nanoparticles into the PBS matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesize and Crystallization Kinetics of Biodegradable Aliphatic Poly(Butylene Succinate-Co-Diethylene Glycol)

Biodegradable aliphatic poly(butylene succinate-co-diethylene succinate) (PBDEGS) were synthesized from succinic acid and diethylene glycol through a two step polycondensation with titanium tetraisoproxide (TTP) as catalyzer and polyphosphate (PPA) as the stablilizer at high temperature. The differential scanning calorimeter (DSC) was used to investigate the melting behavior, crystallization behavior and non-isothermal crystallization kinetics of this copolyester. The melting behavior showed that the melting temperature of the copolyester decreased gradually with increaseing of diethylene glycol in the copolyester. The crystallization mechanism of PBDEGSs were analyzed with the Avrami equation. The result showed that the DEG chains affected the crystallization mechanism of PBS and decreased overall crystallization rate in some extent. The contrastive method of Mo analysis showed similar rasult. At the same time, because of the flexible ether bond existed in the DEG molecules, the crystallization activation energy of PBDEGSs is obviously lower than that of PBS.     

Effect of poly(vinylidene fluoride) polymorphic structures on the crystallization behavior of poly(butylene succinate)

The detail information of both α and β form poly(vinylidene fluoride) (PVDF) crystal effect on the crystallization behavior of poly(butylene succinate) (PBS) were systematically studied. The results show that β form PVDF can obviously improve the melt‐crystallization temperature of PBS during the nonisothermal crystallization process. Both crystallization time span and spherulitic size of PBS decrease with the increasing amount of β form PVDF, which enhances the primary nucleation of PBS. But α form PVDF shows no nucleating effect on PBS crystallization, exhibiting as almost unchanged T_c values for α form PVDF‐blended PBS samples. The intrinsic mechanism for the nucleating effect of β form PVDF on PBS was proposed to be the epitaxial crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40991.     

Crystallization and melting properties of poly(butylene succinate) composites with titanium dioxide nanotubes or hydroxyapatite nanorods

Poly (butylene succinate) (PBS) nanocomposites with titanium dioxide nanotubes (TNTs) or hydroxyapatite nanorods (HAP) were prepared, and the effect of the nano‐inorganics on the nonisothermal crystallization and melting properties of PBS were studied in detail by differential scanning calorimeter. The nonisothermal crystallization kinetics of PBS and its nanocomposites were analyzed by the Avrami, Ozawa, and Mo methods. It is found that the presence of TNTs increases the crystallization temperature and rate of PBS composites, but decreases the crystallization activation energy and crystallinity. By comparison, the crystallization rate of the PBS composite is decreased with the addition of HAP. The melting, recrystallization, and remelting mechanism results in the formation of two melting endothermic peaks during the melting process of neat PBS and its nanocomposites. The model proposed by Mo could successfully describe the nonisothermal crystallization process of PBS and its nanocomposites. At a given crystallinity, the F(t) values decrease in the order of PBS/HAP, PBS, and PBS/TNTs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40335.     

Fractionated crystallization, polymorphic crystalline structure, and spherulite morphology of poly(butylene adipate) in its miscible blend with poly(butylene succinate)

It has been investigated the effects of poly(butylene succinate) (PBS) component on the fractionated crystallization, crystalline structure, and spherulite morphology of polymorphic poly(butylene adipate) (PBA) with melting temperature lower than that of PBS in their miscible binary blends. Fractionated crystallization of the PBA component occurs upon blending with PBS depending on the content and crystallization temperature of the PBS component. It is probably related to the distribution of PBA in the PBS matrix. The PBS component suppresses the crystallization of PBA, due to the physical confinement effect of PBS on the PBA component. PBS is favorable for the formation of the PBA α-crystal in the PBS/PBA blends with C_PBS ≤ 70%, suggesting that the polymorphism of PBA can be regulated by PBS. The morphology observation reveals that the spherulite growth direction of PBA is controlled by that of PBS. Furthermore, the morphology of PBA is also manipulated by that of PBS rather than the crystallization temperature. The possible mechanism of morphology generation of PBA controlled by PBS has been proposed. The PBS/PBA blend system is an ideal system to study not only on the polymorphism regulation but also on morphology control of biodegradable polymorphic material by polymer blending without losing the biodegradability.     

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。