Effect of glycerin on structure transition of PVA/SF blends

Blend films of silk fibrion (SF) and poly(vinyl alcohol) (PVA), with glycerin as an additive, were made, and the structure and properties of the blends were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD) and with an Instron Material Tester. The results showed that SF and PVA are principally incompatible and the blends made by the two polymers were phase‐separated. The results, however, also demonstrated that the blend structure could be changed to some extent by addition of 3–8% glycerin. The boundary of the PVA and SF phases became indistinct, as reported by SEM, a new peak appeared in the WAXD curves, the width of the OH absorption peak in the FT‐IR spectra increased, and the melting points changed in the DSC curves. In particular, the mechanical properties obviously increased, from 350 kg/cm² and 10% of PVA/SF (80/20) film to 832 kg/cm² and 39% of PVA/SF (80/20) film because of the increase in glycerin. It was suggested that glycerin plays a role in building the relationship between PVA and SF, strengthening the interaction between them and improving their compatibility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2342–2347, 2002     

聚乙烯醇薄膜的共混改性

从聚合物结构方面分析了聚乙烯醇（PVA）薄膜的水溶性,提出用共混改性方法提高PVA薄膜的溶解性能。研究了聚丙烯酸不同中和度,不同共混组分组成对薄膜水溶性和力学性能的影响,并利用差示扫描量热法（DSC）、傅立叶红外光谱（FTIR）、广角X射线衍射（WXRD）等手段对共混改性机理进行了分析。     

葡甘聚糖-壳聚糖-聚乙烯醇共混膜的结构表征及性能研究

用溶液共混法制备了葡甘聚糖-壳聚糖-聚乙烯醇共混膜,并用红外光谱(FTIR)、X-射线衍射(XRD)、扫描电镜(SEM)及透光率表征了膜的结构,同时测定了共混膜的力学性能、吸水率、水蒸气透过率。结果表明:共混膜中葡甘聚糖、壳聚糖及聚乙烯醇之间存在着强烈的相互作用和良好的相容性,三者共混明显改善了纯聚合物和二元膜的性能。     

Thermal,Mechanical and Chemical Properties of Hydrophilic Poly(vinyl alcohol) Film Improved by Hydrophobic Poly(propylene glycol)

A series of poly(vinyl alcohol)/poly(propylene glycol) (PVA/PPG) blend films with different PPG contents were prepared by casting the polymer blend solutions. Structure and morphologies of the PVA/PPG blend films were studied by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PVA/PPG blend films were investigated by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), tensile strength tests, and other physical methods. It was revealed that the introduction of PPG could exert marked effects on the morphology and the properties of PVA film.     

木质素磺酸钠与PVA共混薄膜的制备与表征

以木质素磺酸钠(LS)和聚乙烯醇(PVA)为主要原料,添加适量硼砂、明胶在水溶液中溶解共混,流延成膜.通过单因素和正交实验优选了LS/PVA共混膜制备的条件,对共混膜进行了耐水性、形貌、红外、热重、X射线衍射及差示扫描量热分析.结果表明:影响共混膜性能的主要因素有LS含量、硼砂含量以及反应时间,当硼砂含量为2.0%时,...     

Phase separation structure in poly(vinyl alcohol)/silk fibroin blend films

Blend films of a commercial poly(vinyl alcohol) (a-PVA) derived from vinyl acetate and silk fibroin (SF) obtained from degummed silk were prepared by mixing the aqueous solutions of both samples. A plain weave structure was recognized only in the blend films, whereas no structure was found for the superimposed films of both samples. The phase separation structure of the blend films was examined by microscopic observations elongation, tensile tests, and IR measurements. The microphase separation region increased with increase in the degree of polymerization of the PVA. In the IR spectra of the blend films with high PVA contents cast under certain conditions, the absorption peak attributed to the cross-β-form conformation of SF appeared strongly. Gelatin, a water-soluble and natural polymer, was also used for comparison with SF. The ternary phase diagram in an a-PVA/gelatin/H₂O system was obtained experimentally and the critical point was used to estimate the interaction parameter between PVA and gelatin molecules. The phase separation structure and the interaction between PVA and SF molecules were also discussed taking into consideration the results of the a-PVA/gelatin system. © 1998 SCI.     

季铵醚化-辛烯基琥珀酸酯化淀粉与PVA共混膜力学性能研究

为克服淀粉膜脆且硬的缺陷,制备季铵醚化-辛烯基琥珀酸酯化淀粉（QAS）,并将它与聚乙烯醇（PVA）进行混合来制备共混膜;用X射线衍射仪进行共混膜结晶度测定,用扫描电子显微镜观察共混膜的表面形貌,研究QAS/PVA共混比和PVA结构对共混膜力学性能的影响。结果表明,QAS/PVA共混膜的结晶度比QAS膜的结晶度有所降低;随着QAS含量的增加,共混膜的断裂伸长率逐渐减小,断裂强度先减小后增大,当QAS/PVA共混比为50/50（质量比,下同）时,断裂强度达到最小值;随着PVA聚合度和醇解度的增加,共混膜的断裂强度和断裂伸长率也随之增大。     

Structure and Performance of Poly(vinyl alcohol)/Poly(γ-benzyl L-glutamate) Blend Membranes

Poly(vinyl alcohol) (PVA)/poly(γ-benzyl L-glutamate) (PBLG) blend membranes with different PBLG wt contents were prepared by pervaporation. Structure and surface morphologies of PVA/PBLG blend membranes were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PVA/PBLG blend membrane were studied by differential scanning calorimeter (DSC), tensile strength tests, and other physical methods. It was revealed that the introduction of PBLG homopolymer into PVA could exert an outstanding effect on the properties of PVA membrane.     

Studies of chitosan. I. Preparation and characterization of chitosan/poly(vinyl alcohol) blend films

Various blending ratios of chitosan/poly (vinyl alcohol) (CS/PVA) blend films were prepared by solution blend method in this study. The thermal properties and chemical structure characterization of the CS/PVA blend films were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR). Based upon the observation on the DSC thermal analysis, the melting point of PVA is decreased when the amount of CS in the blend film is increased. The FTIR absorption characteristic is changed when the amount of CS in the blend film is varied. Results of X‐ray diffraction (XRD) analysis indicate that the intensity of diffraction peak at 19° of PVA becomes lower and broader with increasing the amount of CS in the CS/PVA blend film. This trend illustrates that the existence of CS decreases the crystallinity of PVA. Although both PVA and CS are hydrophilic biodegradable polymers, the results of water contact angle measurement are still shown as high as 68° and 83° for PVA and for CS films, respectively. A minimum water contact angle (56°) was observed when the blend film contains 50 wt % CS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Phase separation in poly(vinyl alcohol)/gelatin blend systems

Blends of a commercial poly(vinyl alcohol) (a-PVA) derived from vinyl acetate and gelatin obtained from collagen were prepared by mixing aqueous solutions of both samples under various conditions. For the blend hydrogels, the depression of melting temperatures was observed at high PVA content. Similarly to the a-PVA/silk fibroin (SF) system, when the degrees of polymerization of PVA increased, the microphase separation region in a phase diagram of the blend films increased for the a-PVA/gelatin system. In the IR spectra of the blend films, no absorption bands corresponding to a conformational change of gelatin appeared. Comparison of the mechanical properties of the a-PVA/gelatin and a-PVA/SF systems, showed the interaction between PVA and gelatin molecules to be smaller than that between PVA and SF molecules. © 1999 Society of Chemical Industry     

Morphology,mechanical and dynamic mechanical properties of recycled high density polyethylene and poly(vinyl alcohol) blends

Summary  Blends of post-consumer high density polyethylene (HDPEr) and poly(vinyl alcohol) (PVA) were prepared with maleic anhydride-grafted HDPEr (HDPEr-AM), as the compatibilizer, to evaluate the effectiveness of the PVA as a modifier for polyethylene and influence of PVA concentration on the blend properties. Films of polyethylene having biodegradable polymers could be a good solution for agricultural purpose since they can degrade more easily. The blends HDPEr/HDPEr-AM/PVA were investigated by physical tests, dynamic-mechanical analysis (DMA) and scanning electron microscopy (SEM). Thermal properties were measured by means of differential scanning calorimetry (DSC). The blend HDPEr/HDPEr-AM/PVA (50/10/40) with 10wt% of compatibilizer showed the highest tensile strength (28 MPa) compared to the blends (60/40) without compatibilizer (11 MPa). On the other hand, morphologic analysis showed synergism of the polymers in the blend HDPEr/HDPEr-AM/PVA (30/10/60), with 10wt% of compatibilizer. Overall, it was observed that the blend HDPEr/HDPEr-AM/PVA with composition of (70/10/20) showed the best properties for agricultural films processing application.     

Blends of aliphatic polyesters. IV. Morphology,swelling behavior,and surface and bulk properties of blends from hydrophobic poly(L-lactide) and hydrophilic poly(vinyl alcohol)

Blend films were prepared from hydrophobic poly(L -lactide) (PLLA) and hydrophilic poly(vinyl alcohol) (PVA) with different PLLA contents [X_PLLA (w/w) = PLLA/(PVA + PLLA)] by solution casting and melt quenching. Their morphology, swelling behavior, and surface and bulk properties were investigated. Polarizing optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry, and tensile testing revealed that PLLA and PVA were phase separated in these blend films and the PLLA-rich and PVA-rich phases both formed a continuous domain in the blend film of X_PLLA = 0.5. The water absorption of the blend films was higher for the blend films of low X_PLLA values when compared at the same immersion time, and it was larger than expected from those of nonblended PLLA and PVA films. The dynamic contact angles of the blend films were linearly increased with an increase in X_PLLA. The tensile strength and Young's modulus of the dry blend films decreased with a rise in X_PLLA, but this dependence was reversed because of the large decreases in tensile strength and Young's modulus for the blend films having high X_PLLA values after immersion in water. The elongation at break was higher for the wet blend film than for the dry blend film when compared at the same X_PLLA and that of the dry and wet blend films decreased with an increase in X_PLLA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2151–2160, 2001     

Effect of nano-SiO2 on the compatibility of PVA/RSF blend

A series of poly(vinyl alcohol) (PVA)/regenerated silk fibroin (RSF)/nano-silicon dioxide (nano-SiO₂) blend films were prepared by solution casting method, in which nano-SiO₂ was obtained via sol?Cgel process. The structure, properties, and morphology of the films related to the compatibility were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). XRD peaks of PVA/RSF/nano-SiO₂ (1.0?wt?%) blends decreased in intensity indicated that formation of PVA and RSF crystal lattices was hindered by nano-SiO₂ particles. FTIR spectroscopy analysis of PVA/RSF/nano-SiO₂ films confirmed that both Si?CO?CC linkage and hydrogen bonding were formed among PVA, RSF, and nano-SiO₂. SEM showed that there was no obvious phase separation in PVA/RSF/nano-SiO₂ (1.0?wt?%) film although small uniform blur particles can still be found. In addition, TEM showed nano-particles were well dispersed through the PVA/RSF polymer matrix. Besides, the observed shift in glass transition temperatures (T _g) and improvement in thermal properties of composite films suggested the enhanced compatibility due to interfacial bonding and intermolecular interactions. Therefore, these results indicated that the compatibility of PVA/RSF was improved effectively by the addition of nano-SiO₂.     

Preparation of Porous Poly(vinyl alcohol)‐Silk Fibroin (PVA/SF) Blend Membranes

The relation of PVA/SF blending ratio and freezing temperature with the morphology, fine structure and properties of porous PVA/SF blend membranes prepared by means of freeze drying was investigated. It was indicated that the pore diameter of the blend membranes remarkably decreased and the pore density obviously increased with increasing proportion of PVA or decreasing freezing temperature. With increasing proportion of PVA, the crystallinity of the blend membrane increased. When the blend ratio of PVA/SF was larger than 25/75 or 50/50, the strength, the elongation and the initial tensile modulus of the blend membrane increased somewhat and the compressibility decreased a little with increasing proportion of PVA or decreasing freezing temperature. Therefore, by increasing the proportion of PVA or decreasing the freezing temperature, porous SF/PVA blend membranes could be prepared which had smaller pore diameter, larger pore density, higher crystallinity, strength and elongation.     

Blend films from chitosan and konjac glucomannan solutions

Blend films were prepared by blending 7 wt % konjac glucomannan (KGM) aqueous solution with 2 wt % chitosan (CH) in acetate solution and dried at 40°C for 4 h to obtain the transparent films. Their structure and properties were studied by infrared (IR), wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Crystallinities of the blend films decreased with the increase of konjac glucomannan. The thermostability, tensile strength, and breaking elongation of the blend films in dry state were obviously higher than those of both konjac glucomannan and chitosan films. Tensile strength of the dry blend film achieved 73.0MPa when the weight ratio of chitosan to konjac glucomannan was 7:3. The structure analysis indicated that there is a strong interaction between konjac glucomannan and chitosan resulted from intermolecular hydrogen bonds. The water solubility of the blend films was improved by blending with konjac glucomannan, so they have promising applications to soluble antiseptic coating of pills. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 509–515, 2000     

低分子量PVA对PVA共混体系熔融结晶行为的影响

通过熔融挤出制备了低分子量PVA(PVA0599)改性PVA(PVA1799)共混材料,采用差示扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(PLM)研究了PVA0599对PVA共混体系熔融结晶行为的影响,结果表明:低分子量PVA的加入降低了共混材料的熔点和结晶度,且随低分子量PVA含量的增加,共混材料的结晶速率先增加后减小,当加入20%的PVA0599时,结晶速率达最大。共混材料的球晶尺寸随低分子量PVA含量增加逐渐减小,低分子量PVA在一定程度上降低了PVA的结晶能力,抑制了其结晶。     

丝素蛋白-聚乙烯醇共混改性电纺膜的制备

采用静电纺丝技术,以特殊设计的金属丝螺旋盘绕滚筒作为接收装置,制备了具有一定取向的丝素蛋白(SF)-聚乙烯醇(PVA)共混纳米纤维材料。利用扫描电子显微镜(SEM)对纤维形貌进行观察,并通过Image-Pro Plus软件对纤维细度进行测试,探讨了SF与PVA的配比以及纺丝电压、接收距离等静电纺丝参数对所得纳米纤维形貌、细度及其分布的影响。结果表明:将质量浓度为25 kg/L的SF与质量分数为8%的PVA以质量比15∶3.2共混,并采用20 kV的纺丝电压和13 cm的接收距离静电纺时,所得纳米纤维的平均直径约为238 nm,且直径分布较为均匀。采用该法制得的纳米纤维材料具有一定的纤维取向,有利于细胞生长,可应用于生物医药领域。     

The Preparation and Characterization of Esterified Banana Trunk Fibers/Poly(vinyl alcohol) Blend Film

Polymer composite using natural fiber as reinforcement material is getting attention due to easy availability and its low cost. In this work, poly(vinyl alcohol) (PVA)/fatty acid esterified banana trunk fibers (FAGBTF) of various compositions were produced by a solution casting method. The characteristic properties of PVA/ FAGBTF composite films were examined by Fourier Transform Infra-Red (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests. On the whole, the increase in the amount of BTF in the composite systems improved the thermal properties and decreased percentage degree of swelling as compared to pure PVA.     

蓝藻基生物降解共混膜的力学性能

以聚乙烯醇(PVA)和水华蓝藻为主要原料,通过溶液铺膜法制备了蓝藻/PVA共混膜,采用万能试验机,研究了不同助剂对蓝藻/PVA共混膜力学性能的影响。结果表明,蓝藻的添加显著降低了共混膜的力学性能。当添加比例为PVA的1/2时,膜的拉伸强度和断裂伸长率分别比无藻处理下降了65.89%和79.57%。甘油、尿素显著提升了蓝藻/PVA共混膜的断裂伸长率,当添加比例为蓝藻的1/2时,分别能使共混膜的断裂伸长率提高73.20倍和62.02倍。虽然柠檬酸、硅烷偶联剂能够提升蓝藻/PVA共混膜的拉伸强度,但只能在低剂量时促进断裂伸长率的小幅提高,当柠檬酸添加比例为蓝藻的1/40时,膜的断裂伸长率能提高4.41倍,而当硅烷偶联剂添加比例为蓝藻的1/20时,膜的断裂伸长率能提高1.49倍。尿素与甘油复合增塑,更有利于提升共混膜的断裂伸长率。硅烷偶联剂与甘油复合增塑,更有利于提升共混膜的拉伸强度。     

Properties and structure of PVP–lignin “blend films”

Blend films of poly (4‐vinylpyridine) and lignin were prepared by the casting method. Their structure and properties were studied by Fourier transform infrared (FTIR), wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). The IR spectra of the blend films indicated that hydrogen‐bonding interaction occurred between poly (4‐vinylpyridine) and lignin. The glass transition temperature of these blends increased with the increase of lignin content, which indicated that these blends were able to form a miscible phase due to the formation of intermolecular hydrogen bonding between the hydroxyl of lignin and the pyridine ring of poly (4‐vinylpyridine). The thermostability of these blends decreased with the increase of lignin content. Initially, an appreciable increase in the measured tensile strength was achieved with a lignin content of 15%, at which the maximum value of 33.03 MPa tensile strength was reached. At a 10% lignin incorporation level, the blend film exhibited a maximum value of 9.03% strain. When the threshold in lignin content for blend films exceeded that limit of 10% lignin, the strain behavior of these blend films deteriorated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1405–1411, 2005