Fractional Crystallization Kinetics of Poly(ethylene oxide) in Its Blends with Poly(butylene succinate): Molecular Weight Effects

The fractional crystallization kinetics and phase behavior of PEO with different molecular weights (MWs) in its miscible crystalline/crystalline blends with PBS are studied. Both fractional crystallization kinetics and phase segregation of PEO in PBS/PEO blends are dramatically influenced by its MW. PEO with a medium MW (20 kDa) shows a significant fractional crystallization in the blends with PBS crystallized at a high T_IC,PBS, which, however, is dramatically depressed in the blends with a very low or high MW of PEO. This indicates that the PEO component with a medium MW is more ready to segregate into the interlamellar region of PBS crystals than those with a very low or high MW. The MW‐dependent fractional crystallization kinetics and phase segregation of PEO component in the PBS/PEO blends are discussed.

     

Fractional Crystallization and Phase Segregation in Binary Miscible Poly(butylene succinate)/Poly(ethylene oxide) Crystalline Blends: Effect of Crystallization Temperature

The effects of crystallization temperature of PBS (T_IC,PBS) on the fractional crystallization, phase segregation, and crystalline morphology of PEO in their miscible crystalline/crystalline blends are investigated. The crystallization kinetics and phase segregation of PEO are considerably influenced by T_IC,PBS. A higher T_IC,PBS results in the crystallization of PEO at an extremely large degree of supercooling and may facilitate the segregation of PEO within the interlamellar regions of PBS. At a high T_IC,PBS (e.g., 95 °C), the long period, thickness of amorphous and crystalline layers of PBS increase upon blending with PEO. The T_IC,PBS dependence of phase segregation of the PEO component is discussed from a thermodynamic as well as a kinetic perspective.

     

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。     

聚丁二酸丁二醇酯的等温结晶动力学研究

采用差示扫描量热仪(DSC)对聚丁二酸丁二醇酯(PBS)的等温结晶动力学进行了研究,并用Avrami方程对实验数据进行了量化分析。研究结果表明:在等温结晶时,PBS倾向于以均相成核的三维生长方式结晶,并通过偏光显微镜进行了验证;同时,随着结晶温度的升高,PBS的结晶速率常数K值下降,半结晶时间t1/2延长。     

PBS/PBAT共混型全生物降解材料的制备及其性能研究

通过熔融共混法制备了聚丁二酸丁二醇酯（PBS）/聚己二酸对苯二甲酸丁二酯（PBAT）共混物,用熔体流动速率法、扫描量热法、X射线衍射、扫描电镜法及力学性能测试等手段研究了PBS/PBAT共混物的熔体流动性、结晶性能、力学性能以及共混物相容性。结果表明,随着PBAT含量的增加,PBS/PBAT共混体系的拉伸强度先升高后降低,断裂伸长率不断提高,冲击强度先降低后提高;当PBAT含量为20 %（质量分数,下同）时,与纯PBS相比,断裂伸长率提高10倍,冲击强度提高82 %,而拉伸强度仅仅降低6 %。     

Melting behaviour of poly(butylene succinate) in miscible blends with poly(ethylene oxide)

The melting behavior of poly(butylene succinate) (PBSU) in miscible blends with poly(ethylene oxide) (PEO), which is a newly found polymer blends of two crystalline polymers by our group, has been investigated by conventional differential scanning calorimetry (DSC). It was found that PBSU showed double melting behavior after isothermal crystallization from the melt under certain crystallization conditions, which was explained by the model of melting, recrystallization and remelting. The influence of the blend composition, crystallization temperature and scanning rate on the melting behavior of PBSU has been studied extensively. With increasing any of the PEO composition, crystallization temperature and scanning rate, the recrystallization of PBSU was inhibited. Furthermore, temperature modulated differential scanning calorimetry (TMDSC) was also employed in this work to investigate the melting behavior of PBSU in PBSU/PEO blends due to its advantage in the separation of exotherms (including crystallization and recrystallization) from reversible meltings (including the melting of the crystals originally existed prior to the DSC scan and the melting of the crystals formed through the recrystallization during the DSC scan). The TMDSC experiments gave a direct evidence of this melting, recrystallization and remelting model to explain the multiple melting behavior of PBSU in PBSU/PEO blends.     

Biodegradable Blends From Plasticized Soy Meal,Polycaprolactone, and Poly(butylene succinate)

A synergistic effect of simultaneous plasticization and destructurization of soy protein in melt extrusion is studied using soy meal, glycerol, and urea. The combined effect of plasticization and destructurization yields thermoplastic soy meal (TSM) that is capable of chemical interactions with biodegradable polyesters. Melt‐compounded blends of TSM with biodegradable polyesters give new ductile bioplastics. The observed improvement in the properties of these blends might be due to two reason; the high elasticity of the destructured soy meal and the compatibility between the polyesters used. The synergistic effect of unfolding and destructurization of the protein by urea leads to high mobility in the protein chains of the soy meal.

     

生物降解塑料聚丁二酸丁二酯的改性研究进展

对近年来国内外在聚丁二酸丁二酯(PBS)物理与化学改性方面的研究进展情况进行了综述,其中物理改性方面包括无机填料改性、成核剂改性、天然高分子材料改性和生物降解塑料改性等,化学改性方面包括脂肪族聚酯共聚、芳香族聚酯共聚、扩链改性、交联改性等。最后指出了目前PBS改性存在的问题,并对PBS在未来的发展方向作了展望。     

Miscibility and crystallization in crystalline/crystalline blends of poly(butylene succinate)/poly(ethylene oxide)

Miscibility and crystallization behavior have been investigated in blends of poly(butylene succinate) (PBSU) and poly(ethylene oxide) (PEO), both semicrystalline polymers, by differential scanning calorimetry and optical microscopy. Experimental results indicate that PBSU is miscible with PEO as shown by the existence of single composition dependent glass transition temperature over the entire composition range. In addition, the polymer-polymer interaction parameter, obtained from the melting depression of the high-T_m component PBSU using the Flory-Huggins equation, is composition dependent, and its value is always negative. This indicates that PBSU/PEO blends are thermodynamically miscible in the melt. The morphological study of the isothermal crystallization at 95 °C (where only PBSU crystallized) showed the similar crystallization behavior as in amorphous/crystalline blends. Much more attention has been paid to the crystallization and morphology of the low-T_m component PEO, which was studied through both one-step and two-step crystallization. It was found that the crystallization of PEO was affected clearly by the presence of the crystals of PBSU formed through different crystallization processes. The two components crystallized sequentially not simultaneously when the blends were quenched from the melt directly to 50 °C (one-step crystallization), and the PEO spherulites crystallized within the matrix of the crystals of the preexisted PBSU phase. Crystallization at 95 °C followed by quenching to 50 °C (two-step crystallization) also showed the similar crystallization behavior as in one-step crystallization. However, the radial growth rate of the PEO spherulites was reduced significantly in two-step crystallization than in one-step crystallization.     

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。     

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。     

Blends of Poly(hydroxybutyrate) and Poly(ethylene succinate) Prepared in the Presence of Samarium

Blends of the commercial biodegradable polymer poly(hydroxybutyrate) (PHB) with the oligomeric polyester poly(ethylene succinate) (PES) were prepared by melt processing in the presence of Sm(acac)₃. The occurrence of transesterification reactions during blend processing using the samarium catalyst was investigated. ¹H NMR analyses showed no evidence of transreactions, even using high content of catalyst (4 wt%), long reaction times and high temperatures (200°C). Under the drastic reaction conditions employed, chain degradation characterized by a significant decrease in the molecular weight (MW) of PHB has taken place. PHB/PES blends form immiscible systems in which the PHB crystallizes as large spherulites, but its crystallization is significantly influenced by the presence of PES, which does not crystallize at conditions in which the poly(hydroxyalkanoate) is crystallized.     

Blends of poly(ethylene terephthalate) and poly(butylene terephthalate)

Commercial grade poly(ethylene terephthalate), (PET, intrinsic viscosity = 0.80 dL/g) and poly(butylene terephthalate), (PBT, intrinsic viscosity = 1.00 dL/g) were melt blended over the entire composition range using a counterrotating twin‐screw extruder. The mechanical, thermal, electrical, and rheological properties of the blends were studied. All of the blends showed higher impact properties than that of PET or PBT. The 50:50 blend composition exhibited the highest impact value. Other mechanical properties also showed similar trends for blends of this composition. The addition of PBT increased the processability of PET. Differential scanning calorimetry data showed the presence of both phases. For all blends, only a single glass‐transition temperature was observed. The melting characteristics of one phase were influenced by the presence of the other. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 75–82, 2005     

不同PEG含量对PLA/PEG共混物结晶动力学的影响

采用溶液共混法制备了一系列不同配比的聚乳酸(PLA)/聚乙二醇(PEG)共混物。通过偏光显微镜(POM)、扫描电镜(SEM)和差式扫描量热仪(DSC)研究了不同PEG含量的PLA/PEG共混物在不同结晶温度下,聚乳酸的晶体形貌、球晶生长速率及热力学性能。研究发现,PEG能够显著提高聚乳酸球晶的生长速率。当PEG含量为60%时,PLA/PEG共混物中聚乳酸球晶的生长速率最快,达到23.6μm/min,比纯聚乳酸的最快球晶生长速率(0.5μm/min)高47倍。但是,当PEG含量高于60%时,聚乳酸球晶的生长速率有所降低。同时,PLA/PEG共混物中聚乳酸球晶速率随结晶温度变化的取向,均向低温移动。另外,PLA/PEG共混物中聚乳酸球晶呈现环状花纹。DSC测试结果表明,随着PEG含量的增加,PLA/PEG共混物的玻璃化转变温度明显降低。     

Crystallization behaviour of poly(butylene succinate) copolymers

Poly(butylene succinate‐co‐butylene 2‐methyl succinate) (PBSMS) random copolymers were synthesized with various comonomer compositions and their crystallization behaviour and morphology were investigated by differential scanning calorimeter, small angle X‐ray scattering and polarized optical microscopy. The equilibrium melting temperature obtained by the Hoffman–Weeks plot significantly decreased with increasing comonomer concentration containing methyl side‐groups. Spherulitic growth rates were strongly dependent on comonomer concentration and were analyzed using the Lauritzen–Hoffman kinetic theory. The surface free energy (σσ_e) dramatically decreased with comonomer contents. From analysis of the SAXS data, the dependence of the lamellar thickness on crystallization temperature decreased with increasing comonomer concentration. © 2002 Society of Chemical Industry     

Crystallization kinetics and morphology of poly(butylene succinate)/poly(vinyl phenol) blend

Biodegradable crystalline poly(butylene succinate) (PBSU) can form miscible polymer blends with amorphous poly(vinyl phenol) (PVPh). The isothermal crystallization kinetics and morphology of neat and blended PBSU with PVPh were studied by differential scanning calorimetry (DSC), optical microscopy (OM), wide angle X-ray diffraction (WAXD), and small angle X-ray scattering (SAXS) in this work. The overall isothermal crystallization kinetics of neat and blended PBSU was studied with DSC in the crystallization temperature range of 80-88 °C and analyzed by applying the Avrami equation. It was found that blending with PVPh did not change the crystallization mechanism of PBSU, but reduced the crystallization rate compared with that of neat PBSU at the same crystallization temperature. The crystallization rate decreased with increasing crystallization temperature, while the crystallization mechanism did not change for both neat and blended PBSU irrespective of the crystallization temperature. The spherulitic morphology and growth were observed with hot stage OM in a wide crystallization temperature range of 75-100 °C. The spherulitic morphology of PBSU was influenced apparently by the crystallization temperature and the addition of PVPh. The linear spherulitic growth rate was measured and analyzed by the secondary nucleation theory. Through the Lauritzen-Hoffman equation, some parameters of neat and blended PBSU were derived and compared with each other including the nucleation parameter (K_g), the lateral surface free energy (σ), the end-surface free energy (σ_e), and the work of chain folding (q). Blending with PVPh decreased all the aforementioned parameters compared with those of neat PBSU; however, the decrease extent was limited. WAXD result showed that the crystal structure of PBSU was not modified after blending with PVPh. SAXS result showed that the long period of blended PBSU increased, possibly indicating that the amorphous PVPh might reside mainly in the interlamellar region of PBSU.     

The effect of poly(butylene succinate) content on the structure and thermal and mechanical properties of its blends with polylactide

Poly(butylene succinate) (PBS) and polylactide (PLA) were blended in a co‐rotating twin‐screw extruder with various contents of PBS from 0 to 100 wt%. The effect of PBS content on the thermal and mechanical properties of PBS/PLA blends was investigated by using DSC, softening point measurements, a Charpy impact test and tensile testing. The Fourier transform infrared spectra showed that the polymers are immiscible, but the addition of PBS could modify the PLA structure in PBS/PLA blends by changing the content of amorphous and crystalline phases. In addition, the cold crystallization temperature of PLA in blends decreases in comparison with pure PLA, which shows that PBS could have a plasticizing effect on PLA. This is confirmed by the results of DSC analysis. The mechanical properties of the blends depend on the percentage of PBS addition. Typically, the mechanical properties of PBS/PLA blends are intermediate between the properties of the polyesters from which they are obtained. However, in some cases unexpected changes in mechanical properties of the blends were observed. For example, the elongation at break for a PBS/PLA blend containing 10 wt% PLA is higher than for pure PBS. © 2019 Society of Chemical Industry     

聚丁二酸丁二酯的研究进展

主要介绍了聚丁二酸丁二醇酯(PBS)的化学合成技术,包括直接酯化法、酯交换法和扩链法等的情况。而且综述PBS在改性技术方面(包括PBS基脂肪族共聚酯和PBS基共混复合物等改性技术)的进展。最后展望了PBS的应用和发展前景。     

生物可降解聚丁二酸乙二醇酯的合成与降解性能研究

以丁二酸和乙二醇为原料,直接熔融聚合,合成了高相对分子量的聚丁二酸乙二醇酯(PES),用FTIR,1H-NMR表征其结构;考察了不同聚酯反应催化剂对其聚合反应的影响,结果表明:三氧化二锑的催化效果是最佳的。同时,利用酶降解和体外水解的方法,对聚合物降解性能进行研究,结果表明:PES是一种可生物降解的聚合物,且在体外具有一定的降解性。     

高相对分子质量聚丁二酸丁二醇酯的合成与表征

以丁二酸和丁二醇为原料,十氢萘为溶剂,在140~200℃反应12~14 h,进行直接聚合,合成了高相对分子质量聚丁二酸丁二醇酯(PBS)。用FTIR和1HNMR确定了产物为预期化学结构。考察了6种催化剂的催化效果,结果表明,催化剂的催化效果按SnC l2>Ti(OBu)4>Ti(iOPr)4>Sn(Oct)2>Zn(Ac)2≈p-TS顺序递减,SnC l2具有最高的催化效率,以它为催化剂得到的PBS数均相对分子质量达到79 000,产率达到96.0%。当PBS的数均相对分子质量达到40 000以上时,具有很好的力学性能,拉伸强度达到35 MPa,可代替通用塑料。PBS具有良好的生物降解性能,在45 d时生物降解量达到49%,可用作生物降解材料。