The Effect of glycerol on the crystalline,thermal, and tensile properties of CaCl2‐doped starch/PVA films

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl₂ and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl₂‐doped starch/PVA films was studied by X‐ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl₂‐doped starch/PVA films was studied by scanning electron microscopy. The CaCl₂‐doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl₂‐doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl₂, the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl₂‐doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl₂‐doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl₂ and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl₂‐doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. POLYM. COMPOS., 37:3191–3199, 2016. © 2015 Society of Plastics Engineers     

Effect of postcrosslinking modification with glutaraldehyde on the properties of thermoplastic starch/poly(vinyl alcohol) blend films

Thermoplastic starch (TPS)/poly(vinyl alcohol) (PVA) blend films were modified by crosslinking through soaking the films in glutaraldehyde aqueous solution and then heating in an oven. The effects of the concentration of the glutaraldehyde aqueous solution, soaking time, reaction temperature, and time on the crosslinking reaction were investigated. The moisture absorption and mechanical properties of the films were measured to characterize the influence of the crosslinking modification. It was found that the crosslinking modification significantly reduced the moisture sensitivity of the TPS/PVA blend films and increased the tensile strength and Young's modulus but decreased the elongation at break of the TPS/PVA blend films. The described method could be used for posttreating TPS/PVA‐based products to optimize their properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characterization of gamma irradiated plasticized starch/poly(vinyl alcohol) (PLST/PVA) blends and their application as protected edible materials

Blends based on different ratios of plasticized starch (PLST) and poly(vinyl alcohol) (PVA) were prepared in the form of thin films by casting solutions. The effect of gamma-irradiation on thermal, mechanical and morphological properties was investigated. The results of thermogravimetric analysis (TGA), in terms of weight loss and rate of reaction, indicated that the thermal stability of PLST/PVA blends is higher than pure PLST. The differential scanning calorimetry (DSC) scans do not show the glass transition temperature (T_g) of PVA or PLST, but instead a new single glass transition, indicating the occurrence of compatibility. The mechanical testing of PLST/PVA blends showed that tensile strength and elongation at break were increased by increasing the ratio of PVA. At any ratio of PLST/PVA, the tensile strength and elongation at break was found to increase with increasing irradiation dose. As an application in the field of prolonging food preservation lifetime, solutions of gamma irradiated PLST/PVA blends in the presence of chitosan, as an antimicrobial material, were applied to Mango fruits by surface coating. The results showed that this technique would provide suitable materials for food preservation that withstanding the temperature and stresses.     

Properties of starch‐based blend films using citric acid as additive. II

Starch/polyvinyl alcohol (PVA) blend films were prepared by using corn starch, polyvinyl alcohol (PVA), glycerol (GL), and citric acid (CA) as additives and glutaraldehyde (GLU) as crosslinking agent for the mixing process. The additives, drying temperature, and the influence of crosslinker of films on the properties of the films were investigated. The mechanical properties, tensile strength (TS), elongation at break (% E), degree of swelling (DS), and solubility (S) of starch/PVA blend film were examined adding GL and CA as additives. At all measurement results, except for DS, the film adding CA was better than GL because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA, and additives. CA improves the properties of starch/PVA blend film compared with GL. TS, % E, DS, and S of film adding GLU as crosslinking agent were examined. With increasing GLU contents, TS increases but % E, DS, and S value of GL‐added and CA‐added films decrease. When the film was dried at low temperature, the physical properties of the films were clearly improved because the hydrogen bonding was activated at low temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2554–2560, 2006     

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。     

Glycerol‐plasticized spirulina–poly(vinyl alcohol) films with improved mechanical performance

Spirulina–poly(vinyl alcohol) (PVA)–glycerol (SPG) films with improved mechanical performance, especially tensile strength (TS) and the elongation at break (EAB), are fabricated by a casting method. The integrity, color, solubility, microstructure, thermal properties, tensile strength, and compatibility of the SPG films are assessed. SPG films became smooth, homogeneous, and flexible after plasticizing with glycerol. The presence of PVA and hydrogen bonding of PVA with glycerol and spirulina protein improves the water resistance of SPG films by decreasing water absorption of spirulina protein and decreasing water diffusion through the films. The amount of carbonaceous residues decreases from 31% to 14% because of the co‐pyrolysis of spirulina, PVA, and glycerol. TS increases from 2.5 to 26 Mpa and modulus from 53 to 610 Mpa with increasing PVA content. Glycerol enhances film flexibility and EAB up to 50%. Spirulina can be composited with hydrophilic polymers to fabricate compatible, processable and thermally recyclable films with desirable mechanical performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44842.     

Mechanical Properties, Biodegradation and Water Vapor Permeability of Blend Films of Soy Protein Isolate and Poly (vinyl alcohol) Compatibilized by Glycerol

Summary Novel blend films of soy protein isolate (SPI) and poly(vinyl alcohol) (PVA) compatibilized by glycerol were fabricated by preparing a solution, and then casting it on a Teflon-coated metal sheet. Mechanical, biodegradation and water vapor permeability of the blend properties were systematically investigated with various methods. SEM analysis results release that the SPI/PVA/glycerol film degrades at a slower rate than pure SPI. The mechanical test showed that the stress at yield point, stress at break point and Young’s modulus were decreased and percentage elongation at yield point and percentage elongation at break point and of SPI/PVA were increased obviously than pure SPI films. The blend plastics were softened and became semi-rigid contributing to the plasticization of glycerol and the crystalline partion of PVA was destroyed by glycerol. Water vapor permeability of SPI/PVA/glycerol showed the minimum at the component of SPI/PVA (100/35) compatibilized by 3.5% of glycerol.     

Tensile properties,degradation behavior,and water absorption of sago starch plastic films

Sago starch plastic films were prepared by a blending and casting method using various amounts of additives. The additives were glycerol (GLY), polyethylene glycol (PEG), and glutaraldehyde (GLU). Results indicated that the films had an optimum tensile strength of about 2.6 MPa and an optimum elongation at break of 74%. Meanwhile, a GLU content of five parts by weight gave the best tensile properties. Elongation at break of the films increased while tensile strength decreased upon increasing the level of plasticizer (GLY and PEG). The addition of plasticizer also increased the water absorption and soil burial degradation rate. However, the addition of GLU gave opposite results. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Preparation of resistant starch/poly(vinyl alcohol) blend films with added plasticizer and crosslinking agents

We report on the physical properties of films synthesized with native corn starch (NCS) and resistant starch (RS4) prepared with NCS. NCS and RS4/poly(vinyl alcohol) (PVA) blend films were synthesized with a mixing process and casting method. Glycerol (GL) and citric acid (CA) were used as additives. Glutaraldehyde (GLU) was used as a crosslinking agent of the films. RS4 was synthesized with sodium trimetaphosphate and sodium tripolyphosphate as a crosslinker. Then, the RS4 thus synthesized was confirmed by the pancreatin–gravimetry method, swelling power, differential scanning calorimetry, and X‐ray diffraction. The tensile strength, elongation, swelling behavior, and solubility of the films were measured. The results of the measurements indicated that the RS4‐added film was better than the NCS‐added film. In particular, the RS4/PVA blend film with CA as an additive showed physical properties superior to those of the other films. Also, the physical properties with GLU added as a crosslinking agent to the films were investigated. With increasing GLU contents, the tensile strength increased but the elongation, swelling behavior, and solubility values of the GL‐added and CA‐added films decreased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

High‐tensile‐strength polyvinyl alcohol films prepared from freeze/thaw cycled gels

The mechanical properties and molecular structure of a poly(vinyl alcohol) (PVA) film, which was obtained by eliminating water from a PVA hydrogel using repeated freeze/thaw cycles, were investigated by tensile tests, thermal analysis, and X‐ray diffraction measurements. The mechanical properties of PVA with 99.9% saponification were measured as a function of the number of freeze/thaw cycles performed. The tensile strength and Young's modulus increased and the elongation at break decreased with increasing freeze/thaw cycles. The tensile strength and Young's modulus of PVA films obtained after seven freeze/thaw cycles were as high as 255 MPa and 13.5 GPa after annealing at 130°C. Thermal analysis and X‐ray diffraction measurements revealed that this is because of a high crystallinity and a large crystallite size. A good relationship between the tensile strength and the glass transition temperature was obtained, regardless of the degree of saponification and annealing conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40578.     

Effect of starch addition on compression‐molded poly(3‐hydroxybutyrate)/starch blends

Because of their biocompatibility and total biodegradability, poly(3‐hydroxybutyrate) (PHB) and starch have attracted attention as promising raw materials for manufacture of single‐use plastic items and biomaterials. PHB/maize starch blends with starch contents in the range of 0–50 wt % were processed in an internal mixer, and their compression‐molded films were characterized by tensile tests, X‐ray diffraction, thermogravimetric analysis, wettability measurements, and scanning electron microscopy. Water and glycerol were used as plasticizers. The results indicated that the thermal degradation behavior of the blends were similar to that of pure PHB films. All the blends showed heterogeneous morphology, wherein starch granules were dispersed in continuous PHB‐rich matrix. Despite the decrease in elongation at break and tensile strength, starch incorporation of up to 30 wt % into PHB matrix resulted in materials as hard as pure PHB films, but exhibiting less crystallinity and more hydrophilic character, which might lead to a higher biodegradation rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4338–4347, 2006     

高直链玉米淀粉/PVA复合膜的制备

以高直链玉米淀粉为原料,选用乙二醇为增塑剂,硼砂为交联剂,采用流延法制备淀粉/聚乙烯醇(PVA)复合膜。研究不同直链淀粉含量、增塑剂用量、交联剂用量、等因素对复合膜性能的影响。结果表明,高直链淀粉复合膜的性能明显优于普通淀粉复合膜。当淀粉、乙二醇、硼砂用量分别为20%、30%、5%时,复合膜性能最佳。     

Properties of soy protein isolate/poly(vinyl alcohol) blend “green” films: Compatibility,mechanical properties,and thermal stability

Blend films from nature soy protein isolates (SPI) and synthetical poly(vinyl alcohol) (PVA) compatibilized by glycerol were successfully fabricated by a solution‐casting method in this study. Properties of compatibility, mechanical properties, and thermal stability of SPI/PVA films were investigated based on the effect of the PVA concentration. XRD tests confirm that the SPI/PVA films were partially crystalline materials with peaks of 2θ = 20°. And, the addition of glycerol will insert the crystalline structure and destroy the blend microstructure of SPI/PVA. Differential scanning calorimetry (DSC) tests show that SPI/PVA blend polymers have a single glass transition temperature (T_g) between 80 and 115.0°C, which indicate that SPI and PVA have good compatibility. The tension tests show that SPI/PVA films exhibit both higher tensile strength (σ_b) and percentage elongation at break point (P.E.B.). Thermogravimetric analysis (TGA) and water solubility tests show that SPI/PVA blend polymer has more stable stability than pure SPI. All the results reflect that SPI/PVA/glycerol blend film provides a convenient and promising way to prepare soy protein plastics for practical application. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

PVA-魔芋葡甘聚糖包装膜的拉伸性能

在山梨醇与甘油复配增塑剂的作用下,聚乙烯醇与魔芋葡甘聚糖共混形成凝胶状聚电解质水溶液,经流延、干燥,制备了包装膜。结果表明:当共混温度超过80℃,共混时间超过3.5 h,包装膜拉伸强度和断裂拉伸应变急剧下降;复配增塑剂中,山梨醇与甘油的质量比为(1∶1)^1∶3时,有利于提高包装膜的拉伸强度。包装膜拉伸性能变化的微观原因主要是低分子电解质的扩散-停止-继续扩散-析出,从而使共混体系在平衡状态-均相状态-失衡状态-非均相状态之间变化。     

Effect of electron-beam irradiation followed by annealing on the physical properties of poly(vinyl alcohol)–chitosan blend films at different weight ratios

The aim of this study was to examine the effect of electron-beam irradiation followed by annealing on the physical properties of poly(vinyl alcohol) (PVA)–chitosan (CS) blend films. Solution-cast films containing various ratios of polymers were exposed to irradiation doses of 26, 39, and 52 kGy at room temperature and then annealed at 100 °C. The results show that at all doses, with an increase in the weight ratio of CS, the gel content of the samples decreased, and the water absorption of the samples increased. The irradiation dose ranged from 26 to 39 kGy; this led to an increased gel content and a decreased degree of swelling in the samples. However, at 52 kGy, an increase in the amount of swelling was observed. X-ray diffraction analysis and scanning electronic microscopy images of the samples revealed that the increase in the irradiation dose reduced the crystallinity and increased the surface heterogeneity, respectively. The tensile strength of the blends decreased with decreasing PVA–CS weight ratio. This property of the samples increased with dose from 26 to 39 kGy and decreased at 52 kGy. The elongation at break of the samples decreased with both an increase in the irradiation dose and a decrease in the CS content. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47820.     

头发角蛋白塑料的制备和力学性能研究

将头发氧化后得到的角蛋白粉末用模压的方法制备了角蛋白塑料，考察了模压压强、模压温度、头发的氧化时间以及增塑剂水和甘油的含量等对角蛋白塑料力学性能的影响，并对其角蛋白塑料进行了热重分析和红外表征。实验结果表明随着模压压强的增大，塑料的最大拉伸强度升高，断裂伸长率降低。而模压温度对塑料的力学性能影响不大。随着氧化时间的延长，最大拉伸强度升高，断裂伸长率降低。水和甘油都是头发角蛋白塑料良好的增塑剂，水含量为26．8％或甘油含量为20％时的增塑作用最好，此时最大拉伸强度分别可达15．15MPa和25．33MPa，断裂伸长率分别为17．81％和9．65％。     

Preparation and characterization of modified starch‐based plastic film reinforced with short pulp fiber. II. Mechanical properties

Native corn starch‐ and hydroxypropylated starch (HPS‐) based plastic films were prepared using the short pulp fiber as the reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the strain and stress at break and elastic modulus increased with pulp content. With glycerol content, the strain at break increased considerably, but the breaking stress and elastic modulus decreased. And the stress–strain curves showed that the brittleness problem of films was overcome by the pulp, glycerol, and water content. The hydroxypropyl starch films showed results similar to those of the native starch films. The results of the three‐point bending test showed that maximum deflection, flexural strength, and specific work increased with pulp content, but the flexural modulus was the highest at a pulp content of 20%. And with the glycerol content, the maximum deflection and specific work of rupture increased, but the bending elastic modulus decreased. The hydroxypropyl starch films showed results similar to those of native starch films as far as the maximum deflection and flexural strength were concerned, but the bending elastic modulus and specific work of the hydroxypropyl starch films were considerably lower than those of starch films. So it was concluded that the flexibility of films was improved by the hydroxypropylation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2108–2117, 2003     

Crosslinked poly(vinyl alcohol) and starch composite films: Study of their physicomechanical,thermal, and swelling properties

Crosslinked poly(vinyl alcohol) was blended with 10, 20, 40, and 50 wt % starch by a solution‐casting process. The solution‐cast films were dried, and then their physicomechanical properties including tensile strength, tensile elongation, tensile modulus, tear strength and density, and burst strength and density were tested. Thermal analysis was performed by differential scanning calorimetry. A moisture analysis of the PVA/starch films was performed and their moisture content determined. Also investigated were the films'resistance to solubility in water, 5% acetic acid, 50% ethanol, and sunflower oil and their swelling characteristics in 50% ethanol and sunflower oil. The prepared PVA/starch blends showed significant improvement in tensile modulus and in resistance to solubility in water, 5% acetic acid, and 50% ethanol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1127–1132, 2007     

Preparation and properties of poly(vinyl alcohol) films using carbohydrates as plasticizers

Three nontoxic carbohydrates (ribose, xylose, fructose) were used as poly(vinyl alcohol) (PVA) plasticizers to prepare PVA films using a casting method. Fourier transform infrared spectra demonstrated that hydrogen bonds formed between the carbohydrate and PVA. The crystallinity of raw PVA and PVA film plasticized by carbohydrate was characterized by X‐ray diffraction. Differential scanning calorimetry showed that carbohydrate decreased the melting point (T_m) of PVA. The decomposition temperature of PVA increased with addition of carbohydrate. The thermal stability of PVA film plasticized by carbohydrate (CAPF) was higher than that of PVA film plasticized by glycerol (GLPF). The thermal processing window of CAPF was broader than that of GLPF. The water vapor resistance of CAPF was better than that of GLPF. The mechanical properties of PVA films stored at different relative humidity were studied. Generally, the tensile strength of CAPF was larger than that of GLPF, while the elongation at break of CAPF was close to that of GLPF. Our experimental results indicate that carbohydrates are effective plasticizers for PVA. J. VINYL ADDIT. TECHNOL., 25:E181–E187, 2019. © 2018 Society of Plastics Engineers     

Thermal,mechanical, and surface characterization of starch–poly(vinyl alcohol) blends and borax‐crosslinked films

Starch–poly(vinyl alcohol) (PVA) blends with different compositions were prepared and crosslinked with borax by in situ and posttreatment methods. Various amounts of glycerol and poly(ethylene glycol) with a molecular weight of 400 were added to the formulations as plasticizers. The pure starch–PVA blends and the crosslinked blends were subjected to differential scanning calorimetry, thermogravimetry, and X‐ray photoelectron spectroscopic studies. Broido and Coats–Redfern equations were used to calculate the thermal decomposition kinetic parameters. The tensile strengths and elongation percentages of the films were also evaluated. The results suggested that the glass‐transition temperature (T_g) and the melting temperature strongly depended on the plasticizer concentration. The enthalpy relaxation phenomenon was dependent on the starch content in the pure blend. The crosslinked films showed higher stability and lower T_g's than pure PVA and starch–PVA blends, respectively. High‐resolution X‐ray photoelectron spectroscopy provided a method of differentiating the presence of various carbons associated with different environments in the films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1313–1322, 2005