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     

Effects of additives with different functional groups on the physical properties of starch/PVA blend film

The effects of additives with different functional groups, that is, hydroxyl and carboxyl groups, on the physical properties of starch/PVA blend films were examined. Starch/PVA blend films were prepared by the mixing process. Glycerol (GL) with 3 hydroxyl groups, succinic acid (SA) with 2 carboxyl groups, malic acid (MA) with 1 hydroxyl and 2 carboxyl groups, and tartaric acid (TA) with 2 hydroxyl and 2 carboxyl groups were used as additives. The results of measured tensile strength and elongation verified that hydroxyl and carboxyl groups as functional groups increased the flexibility and strength of the film. The degree of swelling (DS) and solubility (S) of the GL/SA‐added films were low. However, the DS and S of the films with added MA or TA with both hydroxyl and carboxyl groups were comparatively high. When the film was dried at low temperature, the properties of the films evidently improved, probably because hydrogen bonding was activated at low temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3733–3740, 2006     

Poly (vinyl alcohol)/polylactic acid blend film with enhanced processability,compatibility, and mechanical property fabricated via melt processing

Poly (vinyl alcohol)/polylactic acid (PVA/PLA) blend film, which is environment friendly and has potential applications in food and electronic packaging fields, was fabricated by melt extrusion casting. Fourier transform infrared spectroscopy analysis confirmed the formation of the hydrogen bonding between PLA and PVA, which improved the compatibility of PLA with PVA, making PLA uniformly dispersed in PVA matrix as small spheres, even when PLA content increase to 15 wt%. In this way, the original hydrogen bond network among PVA was disturbed and the chain mobility of PVA was activated, endowing PVA/PLA blends with lower melt viscosity than bot modified PVA and PLA, and the blend films with the increased crystallinity, mechanical property, and water resistance. Compared with PVA film, the crystallinity, tensile strength and Young's modulus of the blend film with 15 wt% PLA, respectively, increased by 15.1%, 9 and 51 MPa, and the water contact angle enlarged from 23° to 60°.     

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,...     

尿素/甲酰胺增塑PVA的性能研究

采用流延成膜法制备了以尿素/甲酰胺为复配增塑剂改性的聚乙烯醇(PVA)改性薄膜。采用FTIR研究了复配增塑剂尿素/甲酰胺和PVA之间的相互作用,采用XRD、DSC、TGA和拉伸性能测定对改性后的PVA膜性能进行了测试表征。结果表明,尿素/甲酰胺能与PVA形成氢键作用,破坏PVA的结晶结构,降低PVA膜的结晶度。尿素/甲酰胺的加入降低了PVA的熔点,提高了PVA的热分解温度。改性后的PVA膜的拉伸强度降低,断裂伸长率提高。     

淀粉/三聚氰胺增塑PVA熔融加工膜的制备及性能

以淀粉/三聚氰胺为复配增塑剂,利用熔融加工工艺制备聚乙烯醇(PVA)膜,采用差示扫描量热(DSC)、热失重分析(TG)和力学性能测试等考察了增塑剂含量对PVA膜性能的影响。结果表明,复配增塑剂能有效破坏分子链间氢键,对PVA的增塑作用明显。随增塑剂含量增大,PVA膜的力学性能和熔体质量流动速率呈先增大后减小的趋势,熔点和结晶度先减小后增大。过多的增塑剂易发生溶失,并降低PVA膜的溶胀率,增塑剂含量为10%时,PVA膜的拉伸强度和断裂伸长率分别为60.7 MPa和246.6%,且加工性能和热稳定性明显提升,有利于PVA膜熔融加工。     

Fabrication of water‐soluble poly(vinyl alcohol)‐based composites with improved thermal behavior for potential three‐dimensional printing application

Water‐soluble support materials are essential for fabrication of three‐dimensional printing component, in particular of fused deposition modeling (FDM) process. Poly(vinyl alcohol) (PVA) was considered as a potential ideal candidate used in rapid prototyping technology, while its properties and process‐ability need to be improved for the wide application. This article attempts to use urea/caprolatam (UC) as modification additive for tuning the thermal and mechanical properties of PVA. PVA‐based films with different content of additives were prepared by solution casting method. The results showed that with the increase of UC, PVA films showed decreased crystallinity and melting temperature, while the initial degradation temperature and melt index were increased. The corporation of UC decreased the melting temperature to 173.04 °C and PVA composite with 4.5% crystallinity was fabricated. Due to the formation of hydrogen bonding between UC and the hydroxyl group of PVA, the tensile strength and modulus of PVA were slightly decreased, while strain‐at‐break was significantly enhanced, as high as 470.24%, indicating UC behaved as good plasticizing effect. The microstructure examination via scanning electron microscopy showed that when the content of UC was less than 30% in the composites, homogeneous phase could be observed, indicating good compatibility between these two components. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44966.     

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     

聚乙二醇改性聚乳酸/乙酰柠檬酸三丁酯复合薄膜的结构及性能

以聚乳酸（PLA）为基材、乙酰柠檬酸三丁酯（ATBC）为增塑剂、聚乙二醇（PEG）为增韧剂采用溶液共混法涂覆制备PLA复合薄膜。采用红外吸收光谱、热分析、X射线衍射、扫描电子显微镜及拉伸测试表征PLA复合薄膜的结构和性能。结果表明,适量的PEG改性PLA/ATBC复合薄膜后,使其拉伸强度从29.52 MPa增加到33.40 MPa,断裂伸长率从262 %增加到292 %,薄膜的柔韧性得到增强;PEG的端羟基与PLA的羰基发生缔合反应形成氢键,提高了PLA/ATBC复合薄膜的热稳定性和结晶度;观察90 d后的薄膜表面SEM图像,发现PEG改性后的PLA/ATBC复合薄膜表面没有龟裂纹的产生,延长了其使用寿命;加入微量的爽滑剂乙撑双硬脂酰胺（EBS）改善了PLA复合薄膜的相容性和加工性能。     

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     

Preparation and characterization of poly(vinyl alcohol) nanofiber mats crosslinked with blocked isocyanate prepolymer

Poly(vinyl alcohol) (PVA) nanofibers crosslinked with blocked isocyanate prepolymer (BIP) were successfully prepared using the electrospinning process and subsequent thermal treatment. Fourier transform infrared spectroscopy and solid‐state ¹³C NMR spectroscopy demonstrated that chemical crosslinks between the hydroxyl group of PVA and the isocyanate group of BIP were formed. Thermogravimetric analysis and differential scanning calorimetry results indicated that when the BIP content was increased, the thermal stability of PVA/BIP nanofibers increased, and the crystallinity of PVA decreased. Field emission scanning electron microscopy was used to measure the average diameter (200–300 nm) of the electrospun PVA/BIP nanofibers. The water contact angles were 10.2° and 113° for the pristine PVA nanofibers and PVA nanofibers crosslinked with 8 wt% BIP, respectively. The tensile strength of the crosslinked PVA nanofibers was 53.7 MPa, which was seven times higher than that of pristine PVA. The improved tensile strength and water resistance of the crosslinked PVA/BIP nanofibers were due to a combination of increased crosslinking density and decrease in the number of hydroxyl groups on the surface of the PVA/BIP nanofibers. Copyright © 2010 Society of Chemical Industry     

Enhanced electrical conductivity and structural,mechanical characterization of standalone poly(vinyl alcohol)-graphite nanoplatelets composite films

Polymer based nanocomposites are gaining attention in various fields of science and technology due to its tunable properties. In this work, we report for the first time, the preparation and study on electrical and mechanical properties of standalone poly(vinyl alcohol) (PVA) based graphite nanoplatelet (GnP) composite films using modified film casting technique. Our modified tape casting method can produce films with uniform thickness, and uniform dispersion of filler deprived of pinholes. This technique is scalable for the mass production of polymer composite films for device application. We have obtained a significant enhancement in the electrical conductivity of 9 orders of magnitude and a maximum value of 0.143 S/m using PVA–GnP composites. To the best of our knowledge, this increase is the highest among the reported values for PVA–GnP composite films. However, a reduction in crystallinity and tensile strength can be seen with the addition of GnP fillers. The maximum tensile strength obtained for PVA–GnP composite films was 15 MPa and is adequate for use in electronic applications and devices. The effect of filler addition in PVA is discussed in detail.     

Modification of poly(vinyl alcohol) films by the addition of magnesium chloride hexahydrate

Poly(vinyl alcohol) (PVA) films modified with Magnesium chloride hexahydrate (MgCl₂·6H₂O) were prepared by casting method. The prepared films were characterized by X‐ray diffraction measurements (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and mechanical testing. It was found that the presence of MgCl₂·6H₂O had considerable effects on the crystallinity, thermal, and mechanical properties of PVA films. The crystallization of PVA film was interrupted and the degree of crystallinity of PVA film decreased with the addition of MgCl₂·6H₂O. The glass transition temperature of PVA film decreased with the addition of MgCl₂·6H₂O. After modifying with MgCl₂·6H₂O, PVA film became soft, with lower tensile strength and higher elongation at break. The presence of MgCl₂·6H₂O could significantly increase the moisture content of PVA films and this may be the cause of the plasticizing. POLYM. ENG. SCI., 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     

Preparation of PANI–PVA composite film with good conductivity and strong mechanical property

The polyaniline (PANI)–polyvinyl alcohol (PVA) conductive composite films [doped with hydrochloride (HCl), dodecylbenzene sulphonic acid and amino sulphonic acid (NH₂SO₃H) aqueous solution] were synthesised by ‘in situ’ polymerisation, and their conductivities were compared. Among these composite films, HCl–PANI–PVA composite film possessed the highest conductivity that reached 1360?S·m^??1 [w_(PVA)?=?40%]. Meanwhile, the effects of PVA content, HCl concentration, oxidant ammonium persulphate (APS) dosage, reaction time and film drying temperature on tensile strength of the HCl–PANI–PVA composite films were studied. The tensile strength of the film was improved greatly due to effective mixture of PANI and PVA. When the PVA content was 40%, C_(HCl)?=?1.0?mol·L^??1, reaction time was 4.0?h, n_(APS)/n_(aniline)?=?1.0 and film drying temperature was 80°C, and the tensile strength of the HCl–PANI–PVA composite film reached the maximum of 60.8?MPa. At the same time, the structure of composite materials was characterised and analysed through ultraviolet spectrum and SEM.     

尿素/甲酰胺复配增塑聚乙烯醇薄膜的制备及性能研究

以尿素/甲酰胺为复配增塑剂,采用熔融共混法制备聚乙烯醇（PVA）薄膜。通过傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热仪以及力学测试对PVA薄膜的结构与性能进行表征。结果表明,尿素/甲酰胺复配增塑剂通过破坏PVA分子内与分子间的氢键而影响了PVA分子链的有序结构,在改善PVA加工性能的同时降低了PVA的结晶度,并有效提高了薄膜的韧性。     

Preparation and Characterization of Gelatin-Based PVA Film: Effect of Gamma Irradiation

Gelatin-based polyvinyl alcohol (PVA) films were prepared (using a casting process) by mixing aqueous solutions of gelatin and PVA in different ratios. Monomer 1, 4-butanediol diacrylate (BDDA) was dissolved in methanol. Films containing 95% gelatin + 5% PVA were soaked in 3% BDDA monomer (w/w). These films were then irradiated under gamma radiation (⁶⁰Co) at different doses (50–500 krad) at a dose rate of 350 krad/h. The physico-mechanical and thermal properties of these films were evaluated. It was evident that 5% PVA-containing gelatin blend film exhibited the highest tensile strength (TS) value at 50 krad (51 MPa), which was 46% higher than that of non-irradiated blend films. It was also found that incorporation of PVA significantly reduced the TS value of the blend films compared to the raw film, whereas elongation at break (Eb) value was increased. A significant improvement of the blend films was also confirmed by thermogravimetric analysis (TGA) and thermo-mechanical analysis (TMA) when the acrylate group (from BDDA) was introduced into the film.     

聚乙烯醇/淀粉纳米晶复合膜的制备及表征

利用蜡质玉米淀粉通过硫酸酸解制备淀粉纳米晶（SN）,并采用溶液流延法制备聚乙烯醇（PVA）/SN复合膜,研究SN对复合膜结构和性能的影响。结果表明,制备的SN样品为盘状颗粒,平均直径为30～60 nm;随着SN含量的增加,PVA/SN复合膜的力学性能和阻隔性能均呈现先增后减的变化;在SN含量为10 %时,复合膜的拉伸和阻隔性能最好,拉伸强度由纯PVA膜的47 MPa提高至54 MPa,气体透过系数相对于纯PVA膜也降低了70 %。     

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.     

Development and compatibility assessment of new composite film based on sugar beet pulp and polyvinyl alcohol intended for packaging applications

In this study, interaction and compatibility between sugar‐beet pulp (SBP) and polyvinyl alcohol (PVA) in blend films was assessed. Film‐forming dispersions of different ratios of SBP to PVA (100/0, 75/25, 50/50, and 25/75) were cast at room temperature. The effects of adding PVA to SBP on the resulting film's physical, mechanical and barrier properties and thermal stability were investigated. X‐ray diffraction and environmental scanning electron microscopy (ESEM) were used to characterize the structure and morphology of the composites. When PVA was also added to the composite films, the films became softer, less rigid and more stretchable than pure SBP films. The addition of PVA gave significantly greater elongation at break (12.45%) and lower water vapor permeability (1.55 × 10^?10 g s^?1 m^?1 Pa^?1), but tensile strength did not markedly change, remaining around 59.68 MPa. Thermogravimetric analysis also showed that SBP/PVA film had better thermal stability than SBP film. The ESEM results showed that the compatibility of SBP50/PVA50 was better than those of other composite films. These results suggest that when taking all the studied variables into account, composite films formulated with 50% PVA are most suitable for various packaging applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41354.