聚乙烯醇/二氧化钛复合纳米纤维膜的制备和改性

采用静电纺丝技术制备聚乙烯醇/二氧化钛复合纳米纤维膜,利用戊二醛对复合纳米纤维膜进行改性。分析改性前后材料表面形貌、表面化学基团的变化及其耐水性和热性能。结果表明:复合纳米纤维表面粗糙度随二氧化钛含量的增大而增大。改性后纤维形貌保持不变,纤维间出现粘结,材料表面发生羟醛缩合反应,在1600cm~(-1)处出现-C=C红外特征峰,复合纳米纤维膜耐水性显著提高,材料在190℃处的熔融峰消失。     

生物活性聚乙烯醇/羟基磷灰石复合水凝胶的结构与性能

本工作研究了聚乙烯醇和羟基磷灰石复合型生物活性水凝胶,探讨了工艺条件和配方对其拉伸强度,压缩强度,粘弹性、润滑性等生物力学性能的影响,观察和比较了复合水凝胶的微观形貌.研究表明聚乙烯醇和羟基磷灰石可形成接近纳米级的均匀分散结构,良好相容,使复合凝胶的力学强度和润滑性能提高,其应力松弛性能更接近天然软骨的粘弹性.     

Preparation and Characterization of the Ferroelectric Potassium Nitrate: Poly(vinyl alcohol) Composite Films

The composite films of ferroelectric potassium nitrate (KNO₃):poly(vinyl alcohol) (PVA) with different weight percentages of KNO₃ have been prepared at 200°C using the spray-deposition technique. The remanent polarization (P_r) and peak current density for all composite films was estimated by tracing the polarization-electric field (P-E) hysteresis loop and current density-electric field (J-E) loop, respectively, using a modified Sawyer-Tower circuit. Pure KNO₃ is known not to exhibit any ferroelectricity under ambient conditions, but the X-ray diffraction (XRD) studies of PVA:KNO₃ composite films reveal the presence of a ferroelectric phase III of KNO₃ in the composite films at room temperature. The composite film containing KNO₃:PVA in equal proportions shows maximum Pr and peak intensity ratio of approximately 20.10 μC/ cm² and 2.67, respectively, at room temperature. The J-E and capacitance voltage (C-V) characteristics exhibit butterfly features that supports the presence of a ferroelectric phase in the composite films. The field emission scanning electron microscopy (FE-SEM) image of the composite film containing equal proportions of KNO₃ and PVA shows the homogenous distribution of spherical grains of KNO3 of size ~225 nm.     

改性三叶形聚乙烯醇纤维/环氧树脂复合材料的结构与性能

异形截面纤维大的比表面积有利于提高纤维与基体树脂间的界面结合,改善复合材料的强度和韧性.文中采用环氧氯丙烷对熔纺三叶形聚乙烯醇(PVA)纤维进行表面改性,通过模压成型首次制备了改性三叶形PVA纤维/环氧树脂复合材料.对比研究了改性前后三叶形PVA纤维表面结构和性能及对复合材料力学性能的影响.结果表明,改性后三叶形PVA...     

聚乙烯醇/海藻酸钠复合纳米纤维膜的制备和交联改性

采用静电纺丝技术制备聚乙烯醇/海藻酸钠复合纳米纤维膜,利用氯化钙乙醇溶液进行交联改性。研究复合纳米纤维制备、交联工艺对材料表面形貌、耐水性、热性能等的影响。结果表明:纳米纤维直径在200~500nm之间,纤维平均直径随海藻酸钠含量的增大而增大,复合纳米纤维结晶度随海藻酸钠含量的增大而降低,热稳定性随海藻酸钠含量的增大而下降。交联改性后复合纳米纤维材料耐水性提高,纤维形貌保持,纤维之间粘结增多,材料不发生熔融相转变,热稳定性下降。     

秸秆／聚氯乙烯复合材料的初步研究

本文介绍了一种新型的秸秆处理方法 ,即将秸秆与聚氯乙烯复合制备替代木材使用的秸秆 /塑料复合材料。主要从秸秆含量、处理剂含量对复合材料的力学性能和成型加工性能的影响 ,以及复合材料的形态等方面进行了研究。     

Poly(vinyl alcohol) nanocomposite films containing chemically exfoliated molybdenum disulfide

Molybdenum disulfide (2H-MoS₂) was exfoliated in water after reaction with n-butyl-lithium. Using either alkaline or neutral conditions, different amounts of the resulting single-layer suspension were employed as filler for the production of poly(vinyl alcohol) films containing distinct disulfide contents. These nanocomposite films were obtained by wet casting and were further characterized by powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) and Raman spectroscopies. The mechanical properties of the films were also evaluated. Characterization studies revealed the attainment of homogeneous nanocomposite films in both alkaline and neutral conditions, indicating good distribution and interaction of the hydrophilic filler with the polyhydroxylated polymer. Improved Young's (tensile) modulus (+57%) and tensile strength (+9%) as well as reduced elongation (−78%) were achieved only when the neutral suspension of single layers was utilized. Increased MoS₂ content diminished the crystallinity of the polymer, while enhanced mechanical properties were obtained in the presence of intermediate filler content (around 1 wt%).     

Poly(vinyl alcohol) as versatile biomaterial for potential biomedical applications

In this paper, we present some new case examples where the chemical versatility of poly (vinyl alcohol) (PVA) can be used for potential biomedical applications. PVA, the polymeric material used for designing new nanostructured devices, is water soluble, biocompatible and has excellent physical properties. We point out the possibility of obtaining wall-to-wall chemical hydrogels as well as microgels without diminishing the biocompatibility available in the starting PVA material. Injectability is another important factor to take into account in controlled drug delivery for gene therapy. In this respect, in this paper, established and more innovative methods are prospected in order to obtain particles with dimensions suitable for these applications.     

Poly(vinyl alcohol)–hydroxyapatite biomimetic scaffold for tissue regeneration

Hydroxyapatite–poly(vinyl alcohol) composite blocks were produced by freeze–thawing in situ synthesized hybrid suspension. Matrix mediated precipitation of hydroxyapatite particles in the polymer, controlled the particle size in nanometer range (< 100 nm) and hydrogelation induced an ordered three-dimensional assembly of the particles. Morphological and crystallographic characterization revealed the formation of a macro-porous hydroxyapatite–poly(vinyl alcohol) nanocomposite block. Initial results indicate compositional dependence of modulus of elasticity of the composite.     

聚苯胺-聚氯乙烯复合物的研究

作为导电聚合物中的一员,聚苯胺是一类非常有前景的聚合物,而聚氯乙烯是一种重要且应用很广的塑料.概述了聚苯胺与聚氯乙烯的复合方法,包括直接复合、接枝复合、增塑型复合.针对实现聚氯乙烯的可塑性加工重点介绍了增塑型复合,并展望了聚苯胺-聚氯乙烯复合物的应用.     

氯化镁/甘油改性羧甲基淀粉/聚乙烯醇共混材料的结构与性能

为获得改性淀粉/聚乙烯醇(PVA)共混材料的结构与性能特征,以氯化镁/甘油为复配改性剂,采用溶液成膜方法制备了羧甲基淀粉(CMS)/PVA,研究了CMS/PVA复合膜的红外吸收特性、结晶性能、微观形貌、热性能、力学性能及生物降解性。研究结果表明,氯化镁和甘油可与CMS/PVA产生电子相互作用和氢键作用,阻碍CMS/PVA分子链的规整排列,提高羧甲基淀粉与PVA的相容性,降低CMS/PVA的结晶度和热稳定性。氯化镁/甘油复配改性剂对CMS/PVA的力学性能影响显著,可使CMS/PVA断裂伸长率和拉伸强度提高。氯化镁/甘油可促进CMS/PVA的降解,增加氯化镁/甘油复配改性剂中氯化镁的含量可提高复合膜的降解率。     

Poly(vinyl alcohol) reinforced with large-diameter carbon nanotubes via spray winding

For practical application of carbon nanotube (CNT)/polymer composites, it is critical to produce the composites at high speed and large scale. In this study, multi-walled carbon nanotubes (MWNTs) with large diameter (∼45 nm) and polyvinyl alcohol (PVA) were used to increase the processing speed of a recently developed spraying winding technique. The effect of the different winding speed and sprayed solution concentration to the performance of the composite films were investigated. The CNT/PVA composites exhibit tensile strength of up to 1 GPa, and modulus of up to 70 GPa, with a CNT weight fraction of 53%. In addition, an electrical conductivity of 747 S/cm was obtained for the CNT/PVA composites. The good mechanical and electrical properties are attributed to the uniform CNTs and PVA matrix integration and the high degree of tube alignment.     

Poly (vinyl alcohol) hydrogels for pH dependent colon targeted drug delivery

Oral drug administration is convenient with pH dependent drug delivery system since the drug has to pass through different pH environments in gastro intestinal (GI) tract. The pH dependent swelling/shrinking behavior of hydrogel drug carrier controls the drug release without affecting the function of drug. pH dependent hydrogels of poly (vinyl alcohol) (PVA) were prepared by cross linking with maleic acid (MA). The hydrogels were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, DSC, porosimetry, SEM, TEM, biocompatibility study and by measuring their swelling behavior in water, simulated gastric fluid (SGF) and intestinal fluid (SIF). Swelling of the hydrogels was found to be highest in SIF (pH: 7.5) and lowest in SGF (pH: 1.2) resembling that required in colon targeted drug delivery systems. Since the swelling behavior of the gel is pH dependent, these hydrogels were studied for colon targeted drug delivery in an in-vitro set-up resembling the condition of GI tract. The ratio of PVA and MA in the hydrogel was varied to study the effect on the drug diffusion rate. For drug delivery study, vitamin B₁₂ and salicylic acid were used as model drugs. The hydrogel, loaded with model drugs vitamin B₁₂ and salicylic acid also demonstrated colon specific drug release with a relatively higher drug release in SIF (pH: 7.5) than that in SGF (pH: 1.2).     

Poly (vinyl alcohol) hydrogels for pH dependent colon targeted drug delivery

Oral drug administration is convenient with pH dependent drug delivery system since the drug has to pass through different pH environments in gastro intestinal (GI) tract. The pH dependent swelling/shrinking behavior of hydrogel drug carrier controls the drug release without affecting the function of drug. pH dependent hydrogels of poly (vinyl alcohol) (PVA) were prepared by cross linking with maleic acid (MA). The hydrogels were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, DSC, porosimetry, SEM, TEM, biocompatibility study and by measuring their swelling behavior in water, simulated gastric fluid (SGF) and intestinal fluid (SIF). Swelling of the hydrogels was found to be highest in SIF (pH: 7.5) and lowest in SGF (pH: 1.2) resembling that required in colon targeted drug delivery systems. Since the swelling behavior of the gel is pH dependent, these hydrogels were studied for colon targeted drug delivery in an in-vitro set-up resembling the condition of GI tract. The ratio of PVA and MA in the hydrogel was varied to study the effect on the drug diffusion rate. For drug delivery study, vitamin B12 and salicylic acid were used as model drugs. The hydrogel, loaded with model drugs vitamin B12 and salicylic acid also demonstrated colon specific drug release with a relatively higher drug release in SIF (pH: 7.5) than that in SGF (pH: 1.2).     

Poly(aniline-co-m-aminobenzoic acid) deposited on poly(vinyl alcohol): Synthesis and characterization

In this work, we have deposited poly(aniline-co-m-aminobenzoic acid) on poly(vinyl alcohol) (PVA) by in situ polymerization. The polymerization was effected within maleic acid (MA) cross-linked PVA hydrogel. The copolymer was obtained by oxidative polymerization of aniline hydrochloride and m-aminobenzoic acid using ammonium persulfate as an oxidant. Instead of conventional solution polymerization, here synthesis was carried out on APS soaked MA cross-linked PVA (MA–PVA) film where the polymer was in situ deposited in its conducting form. The composite film was characterized by Fourier transform infra red (FT–IR) and ultraviolet visible (UV–VIS) spectroscopy and electrical measurements. Surface morphology of the composite films was studied by field emission scanning electron microscopy (FESEM). The variation of conductivity of the films was studied.     

可溶性聚苯胺/聚乙烯醇掺杂氧化石墨烯复合材料的制备

通过加入十二烷基苯磺酸钠(SDBS)制备了可溶性的聚苯胺/聚乙烯醇掺杂氧化石墨烯导电复合材料。通过XRD、SEM、TEM、FT-IR、TGA、CV对合成的复合材料进行了表征和分析,结果表明聚苯胺/聚乙烯醇能够插入到氧化石墨烯的层间和包裹在氧化石墨烯的表面形成复合物。用十二烷基苯磺酸钠掺杂的聚苯胺/聚乙烯醇/氧化石墨烯材料具有很好的溶解性和导电性能,将复合物进行还原和再次用酸掺杂之后,发现复合材料的导电性得到进一步提升。     

聚乙烯醇/丝素蛋白引导骨组织再生膜材料的制备和性能

通过聚乙烯醇(PVA)与丝素(SF)的物理共混制备出PVA/SF共混膜.由SEM观察到SF以100～200nm的球粒形状均匀地分散在PVA中,拉伸实验表明当SF添加量小于40%时,共混膜的拉伸强度和杨氏模量均随SF添加量的增加而提高.采用交互浸渍法在PVA/SF膜上生长羟基磷灰石,经相同交互浸渍周期,在膜表面生成的HA随SF的增加而增加,说明SF具有更强的引导骨组织生长能力.