SA/PVA可降解复合塑料膜的制备与性能研究

对木薯原淀粉进行乙酰化改性,合成低酯化度的木薯淀粉醋酸酯(SA);经增塑、交联后与聚乙烯醇(PVA)合成可降解的SA/PVA复合塑料膜,重点研究了PVA、甘油、乙二醛的用量及SA的酯化度对复合膜力学性能的影响,并对复合膜性能进行了表征。结果表明:在PVA质量分数为40%,甘油质量分数为14%,乙二醛质量分数为4%时,可以得到力学性能较好的复合塑料膜;与原淀粉/PVA复合膜相比,复合膜致密性提高,玻璃化转变温度降低,结晶度下降,表现出更好的力学性能。     

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     

Synthesis of starch‐based plastic films by electron beam irradiation

Starch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007     

Crosslinked poly(vinyl alcohol) and starch composite films. II. Physicomechanical,thermal properties and swelling studies

Poly(vinyl alcohol) (PVA) was blended with 10, 20, 30, 40, and 50 wt % of starch with and without crosslinking by solution casting process. The solution‐casted films were dried and tested for physicomechanical properties like tensile strength, tensile elongation, tensile modulus, tear and burst strengths, density, and thermal analysis by differential scanning calorimetry (DSC). These PVA/starch films were further characterized for moisture content; solubility resistance in water, 5% acetic acid, 50% ethanol, and sunflower oil; and swelling characteristics in 50% ethanol and sunflower oil. The crosslinked PVA/starch composite films show significant improvement in tensile strength, tensile modulus, tear and burst strengths, and solubility resistance over the uncrosslinked films. Between the crosslinked and uncrosslinked films, the uncrosslinked films have higher tensile elongation, moisture content, moisture absorption, and swelling over the crosslinked films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 909–916, 2007     

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     

Effect of amylose contents of starches on physical properties and biodegradability of starch/PVA-blended films

Recently, synthetic plastics are used widely in various fields, and with increased applications, disposal of waste plastics has become a serious problem. Therefore, development of novel plastics that are degradable by microorganisms in soil has recently been attracting much attention. In this study, starch/PVA-blended films were prepared from commercial starches with the different amylose contents, PVA, and additives by using a simple mixing process and casting method. Glycerol (GL), sorbitol (SO), tartaric acid (TA), and citric acid (CA) were used as additives. The physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), and solubility (S) with amylose contents of starches were investigated. The amylose content of starches was analyzed by the colorimetric method. Thermal analysis of films was measured by using a differential scanning calorimeter (DSC). Finally, biodegradability of the films was evaluated in a 6-month soil burial test. The examination of the physical properties of biodegradable films indicates that with the higher amylose contents of starch used in preparing the film, TS, and DS of films increased, whereas %E and S decreased. The additives containing both carboxyl and hydroxyl groups, i.e. TA and CA, improved the physical properties of films. A thermal analysis of films revealed that the glass transition temperature (T _g) rose because of the increased crystallization of films with the increasing the amylose contents. Also, films degraded rapidly at the beginning and slow degradation took place until the experiment was completed. The films showed 50–80% degradation.     

Adhesion-to-fibers and film properties of etherified–oxidized cassava starch/polyvinyl alcohol blends

In our previous work, it was demonstrated that etherified–oxidized cassava starch (EOCS) showed greater adhesion and film properties than oxidized cassava starch (OCS). Therefore, the purpose of this paper is to reveal if blending EOCS with polyvinyl alcohol (PVA) could further enhance the adhesion of OCS to cotton and polylactic acid (PLA) fibers and toughen OCS film. The EOCS samples were synthesized through etherification of OCS with 3-chloro-2-hydroxypropyl sulfonic acid sodium in an aqueous medium, and were characterized by Fourier transform infrared spectroscopic technique. The apparent viscosity of cooked EOCS/PVA paste was measured, and the adhesion was evaluated by measuring the bonding forces of the blends to cotton and PLA fibers. Film properties were analyzed in terms of tensile strength, breaking elongation, bending endurance, scanning electron microscopy and X-ray diffraction. It was found that blending EOCS with PVA was able to further enhance the adhesion of OCS to both fibers and toughen OCS film. The enhancement in the adhesion and the film toughness was correlated with blending ratio of EOCS to PVA. With the decrease in the ratio, the breaking elongation and bending endurance of the blend films and bonding forces significantly increased. By increasing the degree of substitution (DS) of EOCS, the bonding forces of EOCS/PVA blends to both fibers gradually increased. In the adhesion, the positive influence performed by the ratio is more than that performed by the DS. The EOCS/PVA with a ratio of 50:50 and a DS of 0.031 could be adopted to further improve the adhesion and film toughness of OCS.

     

生物降解复合膜的制备及其性能研究

在氧化醋酸酯淀粉（PMS）和聚乙烯醇（PVA）的共混物中加入羧甲基纤维素（CMC）、海藻酸钠（SA）及AG（AG）,采用流延工艺制备了降解复合薄膜,研究了CMC与SA的配比及AG的加入量对薄膜力学性能和耐水性能的影响,并用红外光谱和扫描电子显微镜对复合膜的结构和形貌进行了表征。结果表明,CMC和SA可有效地改善复合膜的力学性能和耐水性能,当CMC与SA质量比为1∶1时膜的拉伸强度达20.84 MPa,吸水率124.00 %,AG的加入能进一步提高膜的耐水性,吸水率降至83.35 %。     

A starch‐based biodegradable film modified by nano silicon dioxide

The purpose of this work was to improve the properties of the starch/poly(vinyl alcohol) (PVA) films with nano silicon dioxide (nano SiO₂). Starch/PVA/nano‐SiO₂ biodegradable blend films were prepared by a solution casting method. The characteristics of the films were assessed by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The results obtained in this study indicated that the nano‐SiO₂ particles were dispersed evenly within the starch/PVA coating and an intermolecular hydrogen bond and a strong chemical bond C? O? Si were formed in the nano‐SiO₂ and starch/PVA. That the blending of starch, PVA and nano‐SiO₂ particles led to uniform starch/PVA/nano‐SiO₂ blend films with better mechanical properties. In addition, the nano‐SiO₂ particles can improve the water resistance and light transmission of the blend films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

明胶/淀粉/聚乙烯醇复合肥料包膜的结构与性能

以明胶、淀粉和聚乙烯醇为原料,在交联剂戊二醛和增塑剂甘油存在下,用溶液共混法制备了明胶复合肥料膜.采用红外光谱(FT IR)、X-射线衍射、扫描电镜等表征了复合膜的结构,同时测试了膜的拉伸强度、断裂伸长率、耐水性和尿素的释放率.结果表明,原料之间产生了较强的相互作用,形成了一个较稳定的复合体,复合膜具有良好的力学性能和...     

Synthesis of starch esters in ionic liquids

Chemical modification of corn starches with succinic anhydride or acetic anhydride was carried out using 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) as a reaction medium. The reaction progress was followed in terms of the degree of substitution (DS) for the starch derivatives. The results showed that the homogeneous esterification of starch at 5 : 1 molar ratio of anhydride/anhydroglucose units at 100°C led to formation of acetates with DS ranging from 0.37 to 2.35 and succinates with DS ranging from 0.03 to 0.93. Moreover, the reaction media applied could be easily recycled and reused. Further, the formation of starch esters was confirmed by the presence of the carbonyl signal in the FTIR and NMR spectra. It was shown that the starch granules were mostly converted from their crystalline structure into amorphous state in the ionic liquid system under the given reaction conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

丙烯酰胺改性玉米淀粉/PVA复合膜的制备与表征

为了改善聚乙烯醇（PVA）膜的机械性能,选用玉米淀粉为原材料,50℃条件下以过硫酸铵和尿素为引发剂,同时加入丙烯酰胺对淀粉进行接枝改性,制备得到丙烯酰胺改性的玉米淀粉/PVA复合膜。其中,优化改性淀粉的接枝率确定最佳合成条件为淀粉/丙烯酰胺的质量比为3∶7、引发剂过硫酸铵占单体总质量的0.5%、尿素占单体总质量的0.5%。进一步利用优化的改性淀粉为改性剂,制备了系列改性玉米淀粉/PVA复合膜。采用傅里叶红外光谱、扫描电子显微镜（SEM）对复合膜的组成与结构进行表征,同时测定复合膜的机械性能、耐水性、耐热性等物化特性,结果表明30%ST-0.50%APSU改性淀粉的单体转化率为95.0%,接枝率为85.2%。 30%ST-0.50%APSU/PVA复合膜的耐热性能轻微下降,但断裂伸长率提高了256%,耐水性能提高了43.1%。     

Effects of plasticizer/cross-linker on the mechanical and thermal properties of starch/PVA blends

Biodegradable blends of potato starch and polyvinyl alcohol were prepared by solution casting method. Citric acid was employed to introduce the plasticizing effect into the starch materials. Glutaraldehyde as cross-linker was used to enhance the properties of the blend films. Cross-linking is a common method to improve the strength and stability of starch products. The effects of citric acid and glutaraldehyde on the mechanical properties, thermal properties and swelling degree were investigated. The prepared films were measured for their antibacterial activities and biodegradability. The blend samples were characterized by the thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and FTIR analysis techniques. From the mechanical properties study, it was analyzed that the blend films showed improvement in their tensile strength after cross-linking with glutaraldehyde. The SEM micrographs indicated that the blend films were smooth without any cracks, pores and were well cross-linked. The TGA curves showed that there was an increase in the thermal stability of the blend films after cross-linking as compared to uncross-linked blend films. The prepared films showed good antibacterial properties against Gam-positive and Gram-negative bacteria. The biodegradability of the blends was determined by placing the samples in compost soil for different time intervals and were found to be biodegradable in nature.     

酶促酯化制备松香酸淀粉酯的性质及结构表征

以松香和木薯淀粉为原料,二甲基亚砜（DMSO）为溶剂,采用酶催化酯化法在温和条件下制备了取代度0.031～0.092的松香酸淀粉酯,并对其部分理化性质进行了研究。结果表明：松香酸淀粉酯的性能与其取代度密切相关。随着取代度的增大,酯化淀粉产物的可溶指数和溶胀度降低,相对黏度和特性黏度增强,分子链也随取代度的增大而增加。通过对淀粉-碘络合物的紫外光谱分析,发现随着取代度的增大,酯化产物的最大紫外吸收波长向长波长方向移动,且蓝值减小。红外光谱（FT-IR）、核磁氢谱（¹H NMR）、差示热扫描（DSC）、热重差（TGA）和扫描电镜（SEM）对不同取代度的松香酸淀粉酯表征分析的结果表明：酯化产物在1727 cm^-1处产生C O的特性吸收峰,糊化温度及热稳定性相对预处理淀粉有所降低,淀粉颗粒的结晶度下降。     

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.     

超声波强化制备高取代度大米淀粉乙酸酯

高取代度乙酸酯(DS>2)由于其热塑性及疏水性, 在高分子领域应用广泛。以大米淀粉为原料, 对甲苯磺酸为催化剂, 在冰乙酸/乙酸酐体系中, 采用了超声强化方法制备高取代度乙酸酯淀粉, 并用FTIR、XRD 和SEM对产物进行表征。考察了超声作用时间、超声温度、超声功率对大米淀粉乙酸酯取代度(DS)的影响, 并用响应面法对超声条件进行了优化, 得到的最佳工艺如下:超声时间为15.67min, 超声温度为31.33℃, 超声功率为85.60W, 在此条件下, 得到的乙酸酯淀粉的取代度为2.77。由FTIR图谱可知, 乙酸酯淀粉在1750cm^-1、1433cm^-1、1375cm^-1及1239cm^-1处出现了乙酰基的特征峰, 证明成功地制得了高取代度乙酸酯淀粉。XRD和SEM结果表明, 乙酰化后淀粉的结构完全被破坏。研究结果为高取代度淀粉乙酸酯的工业生产提供了依据。     

Effect of magnesium chloride hexahydrate on thermal and mechanical properties of starch/PVA films

Starch/poly(vinyl alcohol) (PVA) blend films were prepared from the aqueous solutions containing starch, PVA and magnesium chloride hexahydrate (MgCl₂.6H₂O). The interaction between MgCl₂.6H₂O and starch/PVA was studied by Fourier transform infrared spectroscopy. The plasticising effect of MgCl₂.6H₂O on starch/PVA film was studied by scanning electron microscopy (SEM), X-ray diffraction, thermogravimetric analysis, dynamic mechanical analysis and tensile testing respectively. The water content of starch/PVA films increased with the content of MgCl₂.6H₂O. The absorbed water can act as the plasticiser for starch/PVA film. The crystals of starch and PVA were destroyed, and the crystallinity of starch/PVA film decreased with the plasticising effect of MgCl₂.6H₂O and water. SEM micrographs showed that the compatibility between starch and PVA improved with the addition of MgCl₂.6H₂O. The toughness of starch/PVA film increased with the content of MgCl₂.6H₂O.     

Biodegradable Composition Based on Low Density Polyethylene

ABSTRACT

Sodium salt of partially carboxymethylated starch (Na-PCMS) with degree of substitution DS 0.58 and starch acetate with DS 1.7 were synthesized from starch. These starch ethers and acetates along with starch, poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA) were blended with low density polyethylene (LDPE) in various proportion using Brabender mixer. Addition of 5% stearic acid as a plasticizer improves the blend compatibility. Change in mechanical properties were monitored and optimum composition of blend were prepared. This blend was studied for growth of Bacillus species (BS) and degradation by means of weight loss and change in mechanical properties viz., tensile strength and % elongation, and total cellular protein. Degradation of pure polymers within one month period was also examined.     

Grafting of vinyl acetate onto low density polyethylene—starch biodegradable films for printing and packaging applications

Starch‐based biodegradable low‐density polyethylene (LDPE) films were used for graft copolymerization of vinyl acetate with ceric ammonium nitrate (CAN) in aqueous acidic medium as redox initiator with nitric acid. The extent of grafting was examined by Fourier‐transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The objective behind the grafting of vinyl acetate onto the LDPE–starch biodegradable films is to make these suitable for printing and packaging applications without affecting the biodegradability of the original films. Copyright © 2004 Society of Chemical Industry