聚乳酸/聚乙烯醇纳米纤维的制备及结构

以二甲基亚砜为溶剂,制备不同配比的聚乳酸(PLLA)和聚乙烯醇(PVA)的混合溶液,静电纺丝制得PLLA/PVA纳米纤维。采用红外光谱仪、原子力显微镜等对PLLA/PVA纳米纤维结构与性能进行了表征。结果表明:PLLA/PVA纳米纤维中PVA上的羟基与PLLA上的羰基形成了氢键,PLLA与PVA之间存在一定的相互作用,但PLLA/PVA纳米纤维存在相分离现象;混合溶液的PLLA质量分数为11%,PVA质量分数为8%时可以得到较好的PLLA/PVA纳米纤维,但PVA质量分数为6%时出现液滴及珠丝,PVA质量分数为4%时,不能制得纳米纤维。     

PVA对碳酸钙、淤泥/不饱和聚酯树脂体系增强的探讨

采用聚乙烯醇(PVA)对碳酸钙、淤泥进行改性并将其作为不饱和聚酯树脂填料。研究了PVA掺量对碳酸钙/不饱和聚酯树脂和淤泥/不饱和聚酯树脂体系力学性能的影响。采用IR、DSC和SEM探讨了PVA对这2类体系的改性机理。实验结果表明:加入5%PVA后,碳酸钙/树脂体系,淤泥/树脂体系弯曲强度分别提高了55.3%和58.4%。PVA对2种体系的改性增强效应均源于PVA与填料和树脂之间氢键的桥梁作用,氢键改善了无机填料与树脂的相容性,这与以往改性剂与碳酸钙反应生成酯酸钙固化物的机理是不同的。     

PA6/PVA共混物的相容性与力学性能研究

制备了聚酰胺6/聚乙烯醇(PA6/PVA)共混物,通过DMA、FTIR、DSC和力学性能测试等方法对共混物进行了表征,利用Hoffman-Weeks方程和Flory熔点下降方程求得了PA6的平衡熔点和两种聚合物的相互作用参数,研究了共混物的相容性和力学性能。结果表明:在氢键的作用下,PA6/PVA共混物具有良好的相容性;PA6与PVA相互作用参数为-0.085,进一步证明了PA6/PVA共混物是热力学相容体系;当PVA含量为50%时,PA6/PVA共混物的相容性和力学性能最佳。     

成核剂TMP-6对PLLA/PDLA共混物结构与性能的影响

以取代芳基磷酸盐类化合物(TMP-6)为成核剂,采用熔融共混的方法制备了聚左旋乳酸/聚右旋乳酸/TMP-6(PLLA/PDLA/TMP-6)共混体系,研究了TMP-6对PLLA/PDLA共混物性能的影响。结果表明:共混物的玻璃化转变温度(Tg)随着TMP-6用量的增加逐渐降低,同时,TMP-6的加入有利于促进立构型聚乳酸复合物(sc-PLA)晶体的形成;共混物的耐热性随着TMP-6用量的增加逐渐提高;TMP-6的加入改善了共混物的力学性能,提高了共混物的断裂伸长率和冲击强度,但其拉伸强度降低;共混物的储能模量、损耗模量以及复合黏度均随着TMP-6用量的增加而降低,这可能是由于TMP-6起到润滑作用,提高了共混物分子的运动能力,从而改善了共混物的加工性。     

纤维素/PVA复合膜的制备及表征

用新型碱脲溶剂溶解纤维素,通过不同方法与聚乙烯醇(PVA)复合,制备得到纤维素/PVA复合膜。通过固体~1H NMR和~(13)C CP/MAS核磁共振技术对纤维素/PVA复合膜的结构进行表征,结果表明PVA对纤维素的结构几乎无影响,PVA与纤维素间的氢键作用使得纤维素/PVA复合膜稳定存在。力学性能测试结果表明,复合膜具有良好的力学性能。通过溶血实验对复合膜的血液相容性进行了表征,在所有的纤维素/PVA复合膜中,通过冷冻-解冻方法得到的纤维素/PVA复合膜的综合性能最好。     

高柔性PLLA/PBF共混膜的制备及性能

为改善高柔性聚乳酸(PLLA)的力学性能，采用聚乳酸为原料，将其与不同质量比例的聚富马酸丁二酯(PBF)共混，制备出聚乳酸/聚富马酸丁二酯(PLLA/PBF)共混薄膜。对PLLA/PBF共混膜的热学性能、力学性能和流变性能进行研究。广角X射线衍射以及差示扫描热量分析结果表明，PBF的加入提高了PLLA薄膜的结晶度，PLLA/PBF12共混薄膜的结晶度最高可达到35.1%。拉伸实验表明，PBF的加入改善了PLLA薄膜的延展性，PLLA/PBF6共混薄膜断裂伸长率最高可达到159.3%,是PLLA薄膜的50倍以上。动态流变测试表明，PLLA、PLLA/PBF3、PLLA/PBF6共混物在熔融状态下均为假塑性流体，PLLA/PBF12、PLLA/PBF24共混物在低频区为假塑性流体，在高频区为牛顿流体。当PBF的质量比分布为3%和6%时，PLLA的熔体黏度显著降低，加工流动性显著提升。     

全生物降解聚乳酸/聚己内酯共混物的研究进展

介绍了完全生物降解聚乳酸(PLA)/聚己内酯(PCL)共混物的研究进展,重点阐述了其相容性、相态结构、熔融结晶行为、力学性能及加工工艺等方面的研究成果。合适的相容剂能够有效改善共混体系相容性,提高PLA/PCL共混物的韧性,并使体系产生协同效应。PCL的加入并未改变PLA的晶型,但却降低了PLA的结晶温度和PLA的结晶度。黏度、剪切速率、界面张力等都是相态结构的影响因素,通过控制这些因素可以实现对相态结构的控制。相对于单组分体系,PLA/PCL共混物力学性能和加工性能得到改善,并适用多种加工工艺。     

辐射交联PVA/PVP/胶原复合水凝胶的制备及性能研究

采用辐射交联与冻融循环相结合的方法,将胶原引入聚乙烯醇(PVA)/聚乙烯基吡咯烷酮(PVP)水凝胶体系,制备具有较高生物活性的PVA/PVP/胶原复合水凝胶。通过含水率、溶胀性能、力学性能及微观结构研究胶原对复合水凝胶结构与性能的影响,并优选最佳体系进行体外细胞毒性实验(MTT法)。研究结果表明,复合水凝胶具有均匀分布的三维多孔结构,胶原的添加增大水凝胶网络空间结构,其初始含水率达92%,并在10 h内达到溶胀平衡,但力学性能降低。辐射交联与冻融循环相结合的方法有利于提高胶原水凝胶制备效率,胶原结构不改变,其体外细胞存活率从PVA/PVP水凝胶的77.3%提高到93.8%,细胞相容性提高。     

可降解包装膜的制备及性能研究

用马来酸酐对玉米淀粉进行酯化处理制得醋酸酯淀粉,以溶液共混法分别制备了原淀粉(ST)/聚乙烯醇(PVA)、醋酸酯淀粉(SA)/聚乙烯醇共混膜,用FTIR表征了共混膜的结构;用DSC分析了共混膜的热性能;比较了共混膜的力学性能。结果表明,共混物的加入破坏了PVA的晶态结构,使共混膜的熔融温度向低温方向移动,热稳定性降低,但SA/PVA共混膜的热稳定大大高于ST/PVA共混膜,说明经酯化处理后淀粉的热稳定性增强。并且SA与PVA的相容性也较ST提高,使其共混膜的力学性能改善。表现为SA/PVA共混膜的力学性能明显高于同比例的ST/PVA共混膜。     

木质素/PVA复合膜的结构和性能研究

以可再生资源木质素磺酸钙(木钙)和聚乙烯醇(PVA)为基料,制备力学强度及耐水性能良好的木质素/PVA复合膜,并采用FT-IR、DSC和SEM对膜的结构进行表征。结果表明,当原料配比为木钙7g、PVA14g、交联助剂10g、尿素7g、硼砂2.5g时,可以得到综合性能优良的木质素/PVA复合膜;体系中的木质素磺酸钙和PVA有较好的相容性,膜表面均匀光滑。木质素/PVA复合膜有望成为一种新型农业地膜材料。     

Miscibility and phase structure of binary blends of poly(L‐lactide) and poly(vinyl alcohol)

Blend films of poly(L ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA) were obtained by evaporation of hexafluoroisopropanol solutions of both components. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid‐state NMR and other conventional methods, such as Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The existence of two series of isolated and constant glass‐transition temperatures (T_g's) independent of the blend composition indicates that PLLA and PVA are immiscible in the amorphous region. However, the DSC data still demonstrates that some degree of compatibility related to blend composition exists in both PLLA/atactic‐PVA (a‐PVA) and PLLA/syndiotactic‐PVA (s‐PVA) blend systems. Furthermore, the formation of interpolymer hydrogen bonding in the amorphous region, which is regarded as the driving force leading to some degree of component compatibility in these immiscible systems, is confirmed by FTIR and further analyzed by ¹³C solid‐state NMR analyses, especially for the blends with low PLLA contents. Although the crystallization kinetics of one component (especially PVA) were affected by another component, WAXD measurement shows that these blends still possess two isolated crystalline PLLA and PVA phases other than the so‐called cocrystalline phase. ¹³C solid‐state NMR analysis excludes the interpolymer hydrogen bonding in the crystalline region. The mechanical properties (tensile strength and elongation at break) of blend films are consistent with the immiscible but somewhat compatible nature of these blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 762–772, 2001     

Effect of triphenyl phosphite as a reactive compatibilizer on the properties of poly(L-lactic acid)/poly(butylene succinate) blends

Reactive blending is an innovative method for the improvement of compatibility of polymer blend. In this work, poly ( _L-lactic acid) and poly (butylene succinate) (PLLA/PBS) blends were prepared by melt blending to ameliorate the toughness of PLLA. Triphenyl phosphite (TPP) was introduced into the PLLA/PBS blends (80/20 by weight) to enhance their compatibility via reactive blending. The effects of TPP on the morphology and properties of PLLA/PBS blends were studied systematically. The increased torque during melt blending demonstrated that the compatibilizer successfully reacted with PLLA and PBS. The mechanical properties of the blends were exceedingly improved only with 0.5 wt% TPP. A reduction tendency of size of the dispersed phase was observed due to the improvement of compatibility. The DSC and DMA results indicate that the T _g of PLLA decreased at a slow rate with the increasing content of TPP. This work provided a simple approach for preparing a kind of high toughed PLLA material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48646.     

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.     

The toughening behavior of PLLA and its asymmetric PLLA/PDLA blends with lower optical purity

Linear poly(d ‐lactide) (PDLA) with various molecular weights is synthesized and incorporated into commercial poly(l ‐lactide) (PLLA) with different optical purities. And then, the crystallization, mechanical and thermal properties of the PLLA and PLLA/PDLA cast films are investigated. In the PLLA and PDLA/PLLA specimens with lower optical purity, few homochiral crystallites (HC) form in all the specimens and only a small amount of PLA stereocomplex crystallites (SC) are observed in the blends. The elongation at break of all the specimens is extraordinary high, >300%. Dynamic mechanical analyses indicate that the destruction temperature increases at first, and then depresses as enlarging the molecular weight of PDLA in these blends. For the PLLA and PLLA/PDLA with higher optical purity, more content of HC develops in neat PLLA, and both SC and HC produce in the PLLA/PDLA specimens. However, the strains of neat specimens and binary blends are much lower than that of specimens with lower optical purity. The specimens with higher optical purity exhibit higher destruction temperatures and lower loss factors. The high content of crystals (SC and HC) would act as the physical cross‐linking points and provide a key factor to impede the deformation of neat PLLA and binary blends during stretching, which should result in the fragile behavior of the PLLA and PLLA/PDLA blends with higher optical purity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44730.     

聚己内酯对聚乳酸/PBAT共混物增容作用的研究

研究了聚己内酯(PCL)作为增容剂对聚乳酸(PLA)与聚己二酸-对苯二甲酸丁二酯(PBAT)的共混物力学性能、热性能、动态力学性能和相容性的影响。结果表明,加入PCL可以改善PLA与PBAT的相容性,提高共混物的冲击强度、拉伸强度和拉伸弹性模量;在PCL含量为2份时共混物两相之间具有良好的相容性。     

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.     

PET/PLA共混物相容性和结晶性能的研究

研究了相容剂钛酸四丁酯[Ti(OBu)4]含量、聚乳酸(PLA)含量对聚对苯二甲酸乙二醇酯(PET)/PLA共混物相容性的影响,探讨了共混物的熔融和结晶行为,并对其结晶形貌进行了观察。结果表明,Ti(OBu)4含量为PLA的4%(质量分数,下同)时,PET/PLA共混物的相容性良好,但当PLA含量超过30%时,共混物出现相分离;PLA的加入使PET的结晶峰变窄,结晶速率增加,且结晶峰温度向高温方向移动;PLA的加入使PET的晶粒尺寸大幅减小,晶粒数目大幅增加,结晶更加完善。     

Mechanical properties, morphology, and crystallization behavior of blends of poly(l-lactide) with poly(butylene succinate-co-l-lactate) and poly(butylene succinate)

The blends of poly(l-lactide) (PLLA) with poly(butylene succinate) (PBS) and poly(butylene succinate-co-l-lactate) (PBSL) containing the lactate unit of ca. 3 mol% were prepared by melt-mixing and subsequent injection molding, and their mechanical properties, morphology, and crystallization behavior have been compared. Dynamic viscoelasticity and SEM measurements of the blends revealed that the extent of the compatibility of PBSL and PBS with PLLA is almost the same, and that the PBSL and PBS components in the blends with a low content of PBSL or PBS (5-20 wt%) are homogenously dispersed as 0.1−0.4 μm particles. The tensile strength and modulus of the blends approximately followed the rule of mixtures over the whole composition range except that those of PLLA/PBS 99/1 blend were exceptionally higher than those of pure PLLA. All the blends showed considerably higher elongation at break than pure PLLA, PBSL, and PBS. Differential scanning calorimetric analysis of the blends revealed that the isothermal and non-isothermal crystallization of the PLLA component is promoted by the addition of a small amount of PBSL, while the addition of PBS was much less effective.     

rPET/POE/LDPE-g-AA复合材料的制备及性能

以回收聚对苯二甲酸乙二酯( rPET)为基体材料,乙烯-辛烯共聚物(POE)为增韧材料,丙烯酸接枝低密度聚乙烯( LDPE-g-AA)为增容剂,制备了rPET/POE/LDPE-g-AA复合材料.分析了POE、LDPE-g-AA对rPET 玻璃化转变温度、断面相结构、结晶性能、力学性能的影响.结果表明,加入POE...