多级结构PHB基电纺纤维膜的制备及性能研究

以聚β-羟基丁酸酯(PHB)为基体,左旋聚乳酸(PLLA)和聚氧乙烯(PEO)为第二组分,采用多层静电纺丝法制备了三层复合的PHB/PLLA/PHB,PHB/PEO/PHB,PHB/PLLA/PEO多级结构PHB基纤维膜,研究了多级结构PHB基纤维膜的形貌、结晶行为、热性能和亲水性能。结果表明:多级结构纤维膜中PHB组分的平均直径为770~790 nm,PEO的平均直径为280~290 nm,PLLA的平均直径为400~410 nm;PHB,PLLA组分在多级结构纤维膜中的晶型均为α晶型,PEO组分为单斜晶型,多级结构PHB基纤维膜中各组分的热性能没有受到影响;多级结构纤维膜的亲水性由强到弱的顺序依次为PHB/PEO/PHB纤维膜、PHB/PEO/PLLA纤维膜、PHB/PLLA/PHB纤维膜、PHB纤维膜,多级结构可改善PHB电纺纤维膜的亲水性。     

可降解多元混构型纤维的制备及降解性能研究

将聚羟基丁酸戊酸酯(PHBV)、左旋聚乳酸(PLLA)以不同比例共混,采用干法纺丝工艺制备复合可降解纤维。运用扫描电子显微镜和X射线衍射仪对纤维的微观形貌和结构进行分析。确定干法纺丝工艺参数为:卷绕速度28.5 m/min,拉伸倍数3倍,拉伸温度90℃。当PHBV与PLLA质量比为1∶1时,所得纤维强度可达2.8 c N/dtex。通过力学以及结晶性能的变化等研究纤维的降解性能。随降解时间的增加断裂强度与断裂伸长率均呈下降趋势,纤维的规整结构遭到破坏,结晶度有所下降。共混比不同的复合纤维在同一周期内其降解程度不同,当PLLA质量分数达80%,降解周期为50 d时,呈现脆性断裂,断裂强度仅为降解前的1/3。     

聚左旋乳酸/聚氧化乙烯共混物的结构和性能

通过熔融共混法制备了一系列不同比例的聚左旋乳酸(PLLA)/聚氧化乙烯(PEO)共混试样,系统研究了PEO含量对PLLA共混物相形态、结晶性能、拉伸性能和冲击性能的影响。结果表明:PLLA/PEO共混物为非均相体系,且随着PEO含量的增加,相分离程度增大。PEO可有效提高PLLA的结晶性能;随着PEO含量的增加,共混物的断裂伸长率逐渐增大。共混物冲击强度值也随着PEO含量的增加而增大,表明PEO的加入显著增加了PLLA的韧性。     

PLA/P34HB共混纤维的制备与性能

采用熔融纺丝法制备了聚乳酸（PLA）/聚（3-羟基丁酸酯-co-4-羟基丁酸酯）（P34HB）共混纤维,分析了P34HB含量对PLA/P34HB共混纤维热学性能、结晶性能和力学性能的影响,并研究了拉伸倍数对P34HB含量为30%(w)的共混纤维性能的影响。结果表明：当拉伸倍数为3倍时,随着P34HB含量的增加,PLA/P34HB共混纤维的结晶度逐渐降低,断裂强度和初始模量逐渐下降,而断裂伸长率逐渐增大;随着拉伸倍数的增大,P34HB含量为30%(w)的PLA/P34HB共混纤维的结晶度、断裂强度和初始模量逐渐提高,断裂伸长率逐渐降低,当拉伸8倍时,共混纤维的断裂强度达到425 MPa,断裂伸长率为15.5%,初始模量为7 005 MPa。     

PHB/PLLA聚酯材料与PHB/PLLA/PEO聚酯材料的体外降解性

对聚β-羟基丁酸酯/聚乳酸（PHB/PLLA）及聚β-羟基丁酸酯/聚乳酸/聚氧乙烯（PHB/PLLA/PEO）膜状样品在37 ℃磷酸缓冲溶液（PBS）/溶菌酶中的降解行为进行了研究,通过定期观察质量损失、降解过程中的热力学性质及样品表面形态变化,发现PHB/PLLA共混未能提高PHB的降解速度,而PEO加入到PHB/PLLA体系中显著提高了PHB、PLLA的降解速度,进而提高了PHB/PLLA共混体系的降解速度。     

高线密度胶原蛋白/PVA共混纤维的制备及其结构性能

在胶原蛋白与聚乙烯醇(PVA)共混溶液中,改变原液中胶原蛋白和聚乙烯醇的组成,由湿法纺丝得到初生纤维,经热拉伸、热定形、缩醛化反应制得线密度大于25dtex的胶原蛋白/PVA共混纤维。共混纤维横截面呈圆形,纤维内部无孔洞及裂纹,表面光滑,断裂强度和初始模量分别达到4.63cN/dtex和160.2cN/dtex,断裂伸长率为25.4%,结晶度为48.6%,水中软化点和回潮率分别为104℃和13.67%。     

PHB/PLLA共混电纺纤维可纺性的研究

采用静电纺丝法制备了聚β-羟基丁酸酯/左旋聚乳酸(PHB/PLLA)共混纤维,探讨了静电纺丝工艺及PHB/PLLA共混电纺纤维的可纺性。结果表明:对共混溶剂氯仿/N,N-二甲基甲酰胺(CF/DMF)体系,随DMF在共混溶剂中含量增加,PHB/PLLA纤维形态由连续的纤维变为微球;对CF溶剂体系,随纺丝溶液浓度增加,PHB/PLLA纤维形态从微球状变为珠状体,再变成纺锤体,最后形成连续纤维;适宜的PHB/PLLA共混电纺纤维的工艺条件如下:PHB/PLLA质量比为1∶1,溶剂为CF,电纺溶液质量分数为4%,推进速度为0.15 mm/min,板间距17 cm,电压18 kV。     

甲壳型液晶高分子成纤及其纤维结构性能初探

研究了不同相对分子质量的甲壳型液晶高分子聚乙烯基对苯二甲酸二(对丁氧基苯)酯(PBPCS)的成纤和纤维结构性能。结果表明:PBPCS在液晶态和各向同性态熔融挤出,所制备的初生纤维力学性能基本相同,纤维强度不高,且比较脆;数均相对分子质量为6.38×105的聚合物制备的初生纤维最大拉伸强度为18.8 MPa,断裂伸长率为2.4%;在130℃,0.3 N的拉伸张力下,对该初生纤维进行5倍拉伸后,纤维的拉伸强度达32.3 MPa,断裂伸长率达37.1%;初生纤维取向指数约60%,经过5倍拉伸后纤维的取向指数达78.3%,比初生纤维提高了25.9%。     

热拉伸工艺对聚甲醛纤维结构与性能的影响

采用自主开发的熔融纺丝设备制备了聚甲醛(POM)初生纤维,将POM初生纤维在130℃下,经热辊或热管在不同拉伸倍数下进行热拉伸制得POM纤维,研究热拉伸工艺对POM纤维结构与性能的影响。结果表明:随着拉伸倍数的增大,POM纤维取向度、结晶度和断裂强度逐渐增大,条干均匀性逐渐得到改善;在相同拉伸倍数(5~7)下,热辊拉伸得到的POM纤维比热管拉伸得到的POM纤维的取向度和结晶度高、强度好,但条干不匀率高;热管拉伸可实现高倍拉伸,最高可拉伸14倍,而热辊拉伸最高可拉伸7倍;热管拉伸14倍时制得的POM纤维力学性能最佳,其断裂强度可达10.76 cN/dtex,断裂伸长率为9.6%;热辊拉伸7倍时,制得的POM纤维力学性能最佳,其断裂强度可达6.92 cN/dtex,断裂伸长率为12.8%。     

聚苯硫醚纤维的制备及性能研究

对聚苯硫醚(PPS)切片进行了熔融纺丝,测定了拉伸倍率、拉伸温度、热定型温度对纤维性能的影响。结果发现,随着拉伸倍率和热定型温度的提高,纤维的断裂强度和熔点都提高,断裂伸长则下降;随着拉伸温度的提高,纤维的熔点降低,断裂强度和双折射率则先降低后升高,出现最低值。在初生纤维的冷结晶温度110℃附近进行拉伸,纤维的断裂强度最低。在310℃对PPS进行纺丝,初生纤维在90℃拉伸4.5倍后,再在180℃紧张热定型5min,获得了断裂强度为3.9 cN/dtex的PPS纤维。     

High molecular weight poly( -lactide) and poly(ethylene oxide) blends: thermal characterization and physical properties

The miscibility of high molecular weight poly( -lactide) PLLA with high molecular weight poly(ethylene oxide) PEO was studied by differential scanning calorimetry. All blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were found to decrease on blending, the equilibrium melting points of PLLA in these blends decreased with increasing PEO fractions. These results suggest the miscibility of PLLA and PEO in the amorphous phase. Mechanical properties of blends with up to 20 weight% PEO were also studied. Changes in mechanical properties were small in blends with less than 10 weight% PEO. At higher PEO concentrations the materials became very flexible, an elongation at break of more than 500% was observed for a blend with 20 weight% PEO. Hydrolytic degradation up to 30 days of the blends showed only a small variation in tensile strength at PEO concentrations less than 15 weight%. As a result of the increased hydrophilicity, however, the blends swelled. Mass loss upon degradation was attributed to partial dissolution of the PEO fraction and to an increased rate of degradation of the PLLA fraction. Significant differences in degradation behaviour between PLLA/PEO blends and (PLLA/PEO/PLLA) triblock-copolymers were observed.     

High molecular weight poly(l-lactide) and poly(ethylene oxide) blends: thermal characterization and physical properties

The miscibility of high molecular weight poly(l-lactide) PLLA with high molecular weight poly(ethylene oxide) PEO was studied by differential scanning calorimetry. All blends containing up to 50 weight% PEO showed single glass transition temperatures. The PLLA and PEO melting temperatures were found to decrease on blending, the equilibrium melting points of PLLA in these blends decreased with increasing PEO fractions. These results suggest the miscibility of PLLA and PEO in the amorphous phase. Mechanical properties of blends with up to 20 weight% PEO were also studied. Changes in mechanical properties were small in blends with less than 10 weight% PEO. At higher PEO concentrations the materials became very flexible, an elongation at break of more than 500% was observed for a blend with 20 weight% PEO. Hydrolytic degradation up to 30 days of the blends showed only a small variation in tensile strength at PEO concentrations less than 15 weight%. As a result of the increased hydrophilicity, however, the blends swelled. Mass loss upon degradation was attributed to partial dissolution of the PEO fraction and to an increased rate of degradation of the PLLA fraction. Significant differences in degradation behaviour between PLLA/PEO blends and (PLLA/PEO/PLLA) triblock-copolymers were observed.     

Enhancement of PVC/ENR blend properties by poly(methyl acrylate) grafted oil palm empty fruit bunch fiber

Effect of oil palm empty fruit bunch (OPEFB) fiber and poly(methyl acrylate) grafted OPEFB on several mechanical properties of poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blends using HAKEE Rheomixer at the rotor speed of 50 rpm, mixing temperature 150°C, and mixing period of 20 min. The fiber loadings were varied from 0 to 30% and the effect of fiber content in the composites on their ultimate tensile strength (UTS), Young's modulus, elongation at break, flexural modulus, hardness, and impact strength were determined. An increasing trend was observed in the Young's modulus, flexural modulus, and hardness with the addition of grafted and ungrafted fiber to the PVC/ENR blends. However the impact strength, UTS, and elongation at break of the composites were found to decrease with the increase in fiber loading. An increase in elongation at break and UTS and decrease in the flexural and Young's modulus was observed with the addition of PMA‐g‐OPEFB fiber compared to ungrafted fiber. This observation indicates that grafting of PMA onto OPEFB impart some flexibility to the blend. The morphology of cryogenically fractured and tensile fracture surfaces of the composites, examined by a scanning electron microscope shows that the adhesion between the fiber and the matrix is improved upon grafting of the OPEFB fiber. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of thermal aging on the biodegradation of PCL,PHB‐V,and their blends with starch in soil compost

Different proportions of starch were blended with poly(β‐hydroxybutyrate)‐co‐poly(β‐hydroxyvalerate) (PHB‐V) or poly(ε‐caprolactone) (PCL) by extrusion, and the mechanical (maximum tensile strength, elongation at break and Young's modulus) and thermal properties (by differential scanning calorimetry) were determined. The biodegradability of the blends in soil compost was also assessed after thermal aging for 192, 425, and 600 h at different temperatures. The maximum tensile strength of the PCL50 blend (containing 50% starch) was 35% lower than that of PCL and that of the PHB‐V50 blend was 60% lower than that of PHB‐V without thermal aging. PHB‐V blends were more biodegradable than PCL blends. For the blends prepared, only the biodegradation of PHB‐V25 was affected by thermal aging. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3539–3546, 2003     

BHET/纳米TiO_2催化合成PET性能的研究

采用对苯二甲酸双羟乙酯(BHET)/纳米TiO_2复合材料为催化剂合成聚酯(PET),研究了催化剂的催化活性以及所合成PET的性能。结果表明:催化剂添加量为16.5μg/g(换算成TiO_2的有效含量)时,酯缩聚时间为80 min,所合成的PET的色度b值达到纤维级聚酯切片一级品标准;PET成型加工性能优异,PET初生纤维拉伸4.0倍时,断裂强度达3.78 cN/dtex,PET薄膜双向拉伸3.7倍时,其断裂强度为116.0 MPa,断裂伸长为122.5%。     

PBT/PEG/LA可降解聚醚酯的合成及纺丝研究

采用对苯二甲酸二甲酯(DNT)、1,4-丁二醇(BDO)、聚乙二醇(PEG)和乳酸(LA)合成了聚对苯二甲酸丁二醇酯(PBT)/PEG/LA可降解聚醚酯,通过纺丝制备了PBT/PEG/LA共聚物纤维。结果表明:红外光谱和核磁共振分析所得聚合物为PBT/PEG/LA。PBT/PEG/LA共聚物在50℃真空预干燥5 h,80℃干燥5 h,控制纺丝温度高于聚醚酯熔点15～30℃可顺利纺丝,纤维质量良好。随着拉伸倍数、热定型温度或时间的增加,纤维的断裂强度提高.断裂伸长率下降。LA摩尔分数高,有利于纤维降解,但纤维熔点和断裂强度相应下降。     

聚乳酸/聚酰胺弹性体/聚乙酸乙烯酯共混纤维的制备及性能研究

以聚乙酸乙烯酯(PVAc)为增容剂,采用熔融共混和熔融纺丝的方法制备了聚乳酸(PLA)/聚酰胺弹性体(PAE)/PVAc共混切片和共混纤维,研究了增容剂的加入对共混切片相容性的影响和共混纤维增韧改性效果的影响.结果 表明,加入PVAc后,分散相粒子尺寸减小,两相界面模糊,相容性提高.随着PAE弹性体含量增加,初生纤维中...     

Porous biodegradable polyesters. I. Preparation of porous poly(L‐lactide) films by extraction of poly(ethylene oxide) from their blends

Porous poly(L ‐lactide) (PLLA) films were prepared by water extraction of poly(ethylene oxide) (PEO) from solution‐cast PLLA and PEO blend films. The dependence of blend ratio and molecular weight of PEO on the porosity and pore size of films was investigated by gravimetry and scanning electron microscopy. The film porosity and extracted weight ratio were in good agreement with the expected for porous films prepared using PEO of low molecular weight (M_w = 1 × 10³), but shifted to lower values than expected when high molecular weight PEO (M_w = 1 × 10⁵) was utilized. The maximum pore size was larger for porous films prepared from PEO having higher molecular weight, when compared at the same blending ratio of PLLA and PEO before water extraction. Differential scanning calorimetry of as‐cast PLLA and PEO blend films revealed that PLLA and PEO were phase‐separated at least after solvent evaporation. On the other hand, comparison of blend films before and after extraction suggested that a small amount of PEO was trapped in the amorphous region between PLLA crystallites even after water extraction and hindered PLLA crystallization during solvent evaporation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 629–637, 2000