聚丁二酸丁二醇酯/聚羟基烷酸酯熔融共混物的结晶及流变力学行为

用熔融共混法制备聚丁二酸丁二醇酯(PBS)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[Poly(3HB-co-4HB)]复合降解材料,利用差示扫描量热(DSC)、旋转流变仪及万能拉力机对其结晶、流变行为及力学性能进行研究。结果表明,在PBS中加入Poly(3HB-co-4HB)后,发现结晶起始温度(To,c)、结晶峰温度(Tp,c)以及结晶结束温度(Te,c)有所提高,结晶度随着Poly(3HB-co-4HB)的增加呈先增大后下降的趋势;PBS/Poly(3HB-co-4HB)复合降解材料随着Poly(3HB-co-4HB)添加量的增大,断裂伸长率和拉伸强度却呈下降趋势;同时剪切储能模量(G′)、剪切损耗模量(G″)呈现出单增趋势。因此,在复合降解材料中添加适量的Poly(3HB-co-4HB)能改善PBS的结晶、流变及力学行为。     

改性纳米二氧化硅/聚己内酯/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的结构与性能研究

利用异丙基三(二辛基焦磷酸酰氧基)钛酸酯偶联剂改性纳米二氧化硅,采用熔融共混挤出法制备聚己内酯(PCL)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P(3HB-co-4HB))/改性纳米二氧化硅(nano-SiO2)复合降解材料;利用红外光谱(FIIR)、万能拉力机、扫描电镜(SEM)、动态力学分析仪(DMA)等研究了改性nano-SiO2对复合材料的表面结构、力学性能等性能的影响。结果表明:改性nano-SiO2含量为4%时,复合降解材料的力学性能有明显的改善;少量添加的改性nano-SiO2可以均匀分散在PCL/P(3HB-co-4HB)基体树脂中,但当加入量过大时,容易发生团聚现象。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/二氧化钛纤维的成纤性能

用不同含量的二氧化钛(TiO2)改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)],并进行了纺丝研究。采用毛细管流变仪、热重分析仪、单丝强力仪测试了P(3HB-co-4HB)/TiO2复合材料的流变性能、热性能、单丝力学性能和回弹性。实验结果表明,P(3HB-co-4HB)和P(3HB-co-4HB)/TiO2为假塑性流体,TiO2可以有效改善材料的加工流动性;提高材料的热稳定性;TiO2的加入使纤维的断裂强度降低;但纤维的弹性恢复率可达100%,退绕性有所改善。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)@海藻酸钠复合纤维膜的制备及其对Pb2+和Cu2+的吸附性

采用三氯甲烷和N,N二甲基甲酰胺（DMF）为溶剂,制备聚（3-羟基丁酸酯-co-4-羟基丁酸酯）（P（3HB-co-4HB））纺丝溶液,并通过静电纺丝技术制备P（3HB-co-4HB）纳米纤维膜,用海藻酸钠（SA）对P（3HB-co-4HB）纳米纤维膜进行包覆,获得P（3HB-co-4HB）@SA复合纤维膜。利用SEM、比表面积仪、原子吸收光谱分别表征了P（3HB-co-4HB）@SA复合纤维膜的纤维形态、比表面积、溶液残留液离子浓度。结果表明:纺丝液浓度在12%时,P（3HB-co-4HB）纤维成纤性好;随着静电压增大,P（3HB-co-4HB）纤维直径先减小后增大。P（3HB-co-4HB）支架材料可以使SA的比表面积提高约3.9倍,P（3HB-co-4HB）@SA复合纤维膜对Cu2+离子、Pb2+离子最大吸附量分别为26.25 mg/g和36.25 mg/g,折算为SA的吸附量分别为364.58 mg/g和503.47 mg/g。      

扩链改性对聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响

以多苯基多亚甲基多异氰酸酯(PAPI)为扩链剂,采用熔融共混法扩链改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]。使用凝胶渗透色谱、热失重分析仪、电子拉力机、毛细管流变仪、旋转流变仪等研究了PAPI添加量对P(3HB-co-4HB)的相对分子质量、热稳定性、力学性能以及流变性能的影响。结果表明,PAPI的使用能够提高P(3HB-co-4HB)的相对分子质量和熔体黏度,并能有效改善P(3HB-co-4HB)的热稳定性和力学性能,成功实现了对P(3HB-co-4HB)的扩链改性。PAPI的添加量为2.0phr时,体系综合性能最佳,其起始分解温度和最大分解温度分别比纯P(3HB-co-4HB)提高了16.7℃和11.4℃,其拉伸强度和断裂伸长率分别比纯P(3HB-co-4HB)提高了21%和218%。     

成核剂对聚(3-羟基丁酸酯-co-4羟基丁酸酯)性能的影响

分别以氮化硼(BN)、BRUGGOLENP250、CaCO3和Tm-3为成核剂,用熔融模压法制备了聚(3-羟基丁酸酯-co-4羟基丁酸酯)[P(3HB-co-4HB)]样品,借用偏光显微镜(POM)、差示扫描量热(DSC)、热重分析(TGA)和扫描电镜(SEM)等考察了成核剂种类及用量对P(3HB-co-4HB)结晶形态、熔点、热分解温度、力学性能及断面形态的影响。结果表明,各种成核剂均能有效细化P(3HB-co-4HB)的球晶尺寸,提高其熔点及热分解温度;当成核剂BN的质量分数为5‰~8‰时,P(3HB-co-4HB)的综合性能最好。     

4-羟基丁酸含量对聚 3-羟基丁酸 与 4-羟基丁酸共聚物性能和结构的影响

目的对3-羟基丁酸4-羟基丁酸共聚酯P(3HB-co-4HB)进行酶解测试。方法通过力学性能测试、失重率分析、热失重分析、X-射线衍射分析、扫描电镜等测试和表征手段对样品的物理性能及生物降解情况进行评价。结果 P(3HB-co-4HB)分子中4HB单体(文中均用摩尔分数表示)的引入提高了材料的柔韧性,材料的脆性下降;失重率方面,4种材料的降解速率从高到低依次为P(3HB)P(3HB-co-5%4HB)(3HB-co-10%4HB)P(3HB-co-15%4HB);酶解前期,材料的热稳定性增强,而酶解后期材料的热稳定性逐渐下降;XRD结果表明材料降解过程中结晶度的变化不明显;P(3HB-co-4HB)分子中随着4HB单体含量的增加,材料表面粗糙度降低,酶解后材料表面被侵蚀,降解速率与失重率结果一致。结论 P(3HB-co-4HB)分子中4HB单体的引入显著影响了材料的机械性能,随着4HB含量的增加,材料的失重率越来越大,热稳定性呈现先上升后下降的趋势,材料表面粗糙度逐渐降低,由于酶解过程属于从表面侵蚀开始,因此酶解过程中样品的结晶度变化不大。     

扩链改性对聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响EI北大核心CSCD

以多苯基多亚甲基多异氰酸酯(PAPI)为扩链剂,采用熔融共混法扩链改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]。使用凝胶渗透色谱、热失重分析仪、电子拉力机、毛细管流变仪、旋转流变仪等研究了PAPI添加量对P(3HB-co-4HB)的相对分子质量、热稳定性、力学性能以及流变性能的影响。结果表明,PAPI的使用能够提高P(3HB-co-4HB)的相对分子质量和熔体黏度,并能有效改善P(3HB-co-4HB)的热稳定性和力学性能,成功实现了对P(3HB-co-4HB)的扩链改性。PAPI的添加量为2.0phr时,体系综合性能最佳,其起始分解温度和最大分解温度分别比纯P(3HB-co-4HB)提高了16.7℃和11.4℃,其拉伸强度和断裂伸长率分别比纯P(3HB-co-4HB)提高了21%和218%。     

SiO2/聚（3-羟基丁酸酯-co-4-羟基丁酸酯）薄膜研究

目的研究纳米SiO2对可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P34HB)包装膜结晶行为和力学性能的影响。方法采用溶液浇铸法制备SiO_2/P34HB纳米复合薄膜,利用红外光谱仪(FTIR)、扫描电镜(SEM)、正置热台显微镜(POM)、差示扫描量热仪(DSC)和万能力学试验机等研究纳米SiO_2对P34HB结构、结晶性和力学性能等的影响。结果纳米SiO_2在P34HB中起到异相成核的作用,SiO2/P34HB复合膜的结晶速率和结晶度得到明显改善。相比P34HB包装膜,当纳米SiO_2质量分数为2%时,SiO_2/P34HB复合膜的弹性模量和拉伸强度分别提高了72.7%和60.9%。结论获得了纳米SiO2改善可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)包装膜结晶度和力学性能的最佳掺杂比例参数。     

钛酸酯偶联剂对聚乳酸/3-羟基丁酸同4-羟基丁酸共聚酯/纳米羟基磷灰石共混体系流变行为的影响

采用异丙基三(二辛基焦磷酸酰氧基)钛酸酯偶联剂对纳米羟基磷灰石(HA)改性,再与聚乳酸(PLA)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(PHA)熔融共混法制备PLA/PHA/HA纳米复合降解材料。利用流变仪对其流变行为进行了研究。结果表明,PLA/PHA基体在没有添加钛酸酯偶联剂和纳米HA时,基体储存模量G′和复数黏度η*随温度升高而逐渐降低;纯的纳米HA的加入可以提高PLA/PHA基体的储存模量G′和损耗模量G″,然而,PLA/PHA/HA纳米复合降解材料引入钛酸酯偶联剂反而会使储存模量G′和损耗模量G″降低。当过量引入钛酸酯偶联剂会明显降低体系线性-非线性转变的临界应变。在190℃,PLA/PHA基体加入纯的纳米HA时,储存模量G′升高,引入钛酸酯偶联剂后,基体储存模量G′反而有一定降低,但所有样品至少在30min内能保持较稳定的线性粘弹行为。     

Fabrication of poly(3-methylthiophene)/poly(ethylene oxide)/ruthenium oxide composite electrospun nanofibers for supercapacitor application

Journal of Materials Science: Materials in Electronics - In the present work, composites of poly(3-methylthiophene)/poly(ethylene oxide)/ruthenium oxide nanofibers (PMT/PEO/RuO2) were fabricated by...     

Optical properties of poly(vinyl chloride)/poly(ethylene oxide) blend

The relatively high dielectric constant poly(vinyl chloride) (PVC) was blended with poly(ethylene oxide) (PEO) polymer electrolytes to improve their electrical conductivity from the optical spectra of the given polymeric system. The optical properties in the UV–visible region of PVC polymer containing 0%, 20%, 50% and 70% by weight PEO are reported. The optical results obtained were analyzed in terms of the absorption formula for non-crystalline materials. The absorption coefficient and the optical band energy gap (E_opt) have been obtained from direct allowed transitions in k-space at room temperature. The width of the tail of localized states in the band gap (ΔE) was evaluated using the Urbach-edges method. It was found that both (E_opt) and (ΔE) vary with the concentration of the PEO complex in the polymer matrix. In addition, a correlation between the energy gap and the ac-conductivity as a function of PEO complex concentration is also reported.     

Viscoelastic properties of poly(butylene terephthalate)/poly(ethylene naphthalate) blends

Melt blends of poly(butylene terephalate) (PBT) and poly(ethylene naphthalate) (PEN) with 30 and 60 wt% PEN were prepared using a single screw extruder and an injection moulding machine. Stress relaxation tests for the specimens of PBT/PEN blends and the homopolymers were carried out using an Instron testing machine in an Instron environmental chamber. The Taguchi method of experimental design analysed how different levels of temperature, PEN content and initial stress affected the relaxation behaviour of PBT/PEN blends and homopolymers. From the response tables and analyses of main and interaction effects, it was shown that the most significant factor was temperature, followed by PEN content and then the initial stress. Consequently, high temperature, low PEN content and high initial stress speeded up stress relaxation rate of specimens. Interaction effects between factors were insignificant. To fit the relaxation curves of the PBT/PEN blends and the homopolymers at different temperatures, PEN contents and the initial stresses, four different equations were attempted with Matlab™, which determined the coefficients of these functions using the experimental data of stress change with time. The simulated curves from the most suitable function among them were shown using the calculated coefficients to predict the relaxation behaviour of PBT/PEN blends (50% PEN) at temperatures of 30 and 60°C with an initial stress of 7 MPa.     

Microcellular extrusion foaming of poly(lactide)/poly(butylene adipate-co-terephthalate) blends

Foamed poly(lactide) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends were processed via the microcellular extrusion process using CO₂ as a blowing agent. Talc has been added to promote heterogeneous nucleation. Two types of PLA/PBAT blend systems were investigated: Ecovio, which is a commercially available compatibilized PLA/PBAT blend; and a non-compatibilized PLA/PBAT blend at the same PLA/PBAT ratio (i.e., 45:55 by weight percent). Six different formulations were investigated: pure PLA, PLA-talc, Ecovio, Ecovio-talc, non-compatibilized PLA/PBAT blend, and non-compatibilized PLA/PBAT-talc. The effects of various processing parameters such as die temperature, talc and compatibilization on various foaming properties such as cell morphology, volume expansion ratio (VER), open cell content (OCC) and crystallinity were investigated. As per the DSC thermograms, it was observed that compatibilization has merged the two distinctive melting peaks of PLA and PBAT into a single peak while lowering the peak temperature. In general, the addition of talc has decreased the average cell size and VER and increased the cell density and crystallinity; however, it has varying effects on the open cell content. Compatibilization has reduced the average cell size and volume expansion but increased the cell density and had varying and no effects on the OCC and crystallinity, respectively. Similar to compatibilization, the die temperature was found to have varying and no effects on the OCC and crystallinity, respectively. Except for PLA and non-compatibilized PLA/PBAT blend, the cell size and VER of all other formulations did not vary much throughout the entire temperature range (130–150 °C). The cell density was found to be insensitive to die temperatures except for Ecovio and Ecovio-talc.     

Biocompatibility and biodegradation of poly(hydroxybutyrate)/poly(ethylene glycol) blend films

Using chloroform as co-solvent, a series of poly(3-hydroxybutyrate) (PHB) and polyethylene glycol (PEG) blend materials with different ratio ranging from 80 : 20 (wt %) to 20 : 80 (wt %) were prepared by solution blend. The blood-compatibility was evaluated by means of platelet clotting time test and exploring its morphological changes. The results showed that PEG played an important role in resisting platelet adhesion. With the increased addition of PEG, the clotting times became longer and the number of platelet adhesion decreased apparently. All platelets were in discrete state, no pseudopodium had been found and no collective phenomenon had been happened. The cell-compatibility was evaluated via Chinese Hamster Lung (CHL) fibroblast cultivation in vitro. The cells cultured on the matrix spread and proliferated well. With the increase of PEG content in the blend films, the number of live cells became more and more. These results indicated that PHB exhibited satisfying cell-compatibility and the addition of PEG also could improve the cell-compatibility of PHB. The biodegradation experiment indicated that the degradation of PHB/PEG was accelerated by enzyme in vitro and the blending of PEG was favorable to degradation.     

Interfacial dispersion of poly(N-isopropylacrylamide)/ gold nanocomposites

The nanoparticle dispersity and interfacial property could be considered as a basis of their further application in the nanostructured materials. In this paper, the dispersity and interfacial phenomena of poly(N-isopropylacrylamide) modified gold nanoparticles were investigated. Firstly, such polymer/gold nanocomposites were demonstrated to have a good dispersity in water, tetrahydrofuran, alcohols and also chloroform, so they were used to entrap fluorescent dye-labelled lipids in chloroform as nanocontainers and subsequently delivery the fluorescent lipids into water as nanocarriers. Secondly, when the nanocomposites in water/chloroform mixture were heated above 35 degrees C, the nanocomposite particles could be partially transferred from water into chloroform across the interface, and they would come back into water again as cooling, displaying a reversible thermal response. Moreover, such polymer/gold nanocomposites at the immiscible water/toluene fluids preferred to assembly into 2-dimensional membranes with variable density at the water/oil interface. The special dispersion properties of the poly(N-isopropylacrylamide)/gold nanocomposites provide many potentials in the future.     

Characterization of electrospun poly(p-dioxanone) and poly(p-dioxanone)/clay nanocomposite fibers

PPDO was successfully electrospun into continuous, ultrafine fibers by using DMSO as solvent for the first time. The concentration of PPDO in DMSO and the electrospinning temperature were optimized. PPDO/LAP nanocomposites were also electrospun in DMSO. At 70 degrees C, ultrafine PPDO fibers were obtained from 35 wt% solution and the PPDO/LAP nanocomposite fibers were yielded from 55 wt% solution. Electrospun fibers of the PPDO/LAP nanocomposites showed higher degree of crystallinity due to the presence of embedded nanoparticles.