CN114907596A - A kind of preparation method of nanocellulose-starch film - Google Patents

Abstract

Translated fromChinese

本发明涉及膜材料技术领域，公开了一种纳米纤维素‑淀粉膜的制备方法，包括步骤：1)将玉米秸秆淀粉溶解于蒸馏水中，糊化，随后加入玉米秸秆纳米纤维素，得到混合液Ⅰ；2)将羧甲基纤维素钠加入蒸馏水中，得到混合液Ⅱ，将混合液Ⅰ与混合液Ⅱ混合后进行搅拌，使羧甲基纤维素钠溶解后，加入甘油继续匀速搅拌，直至得到的膜液完全混合无明显颗粒，随后将膜液进行超声波‑微波协同处理，待除去溶液气泡后将溶液流延于特制玻璃板上，制备得到纳米纤维素‑淀粉膜。本发明采用的纳米纤维素和淀粉，均来源于玉米秸秆废弃物，环保且节省成本；采用超声和微波对膜液进行处理，改善了膜的机械性能、阻湿性能、透气性能、透光性能和溶解性能。

The invention relates to the technical field of film materials, and discloses a method for preparing a nanocellulose-starch film, comprising the steps of: 1) dissolving corn stalk starch in distilled water, gelatinizing, and then adding corn stalk nanocellulose to obtain a mixed solution Ⅰ; 2) Add sodium carboxymethyl cellulose into distilled water to obtain mixed solution II, mix mixed solution I and mixed solution II, and stir to dissolve sodium carboxymethyl cellulose, add glycerin and continue stirring at a constant speed until The obtained film liquid is completely mixed without obvious particles, and then the film liquid is subjected to ultrasonic-microwave synergistic treatment. After removing the solution bubbles, the solution is cast on a special glass plate to prepare a nanocellulose-starch film. The nanocellulose and starch used in the present invention are all derived from corn stalk waste, which is environmentally friendly and cost-saving; ultrasonic and microwave are used to process the film liquid, which improves the mechanical properties, moisture barrier properties, air permeability and light transmission properties of the film. and solubility properties.

Description

Translated fromChinese

一种纳米纤维素-淀粉膜的制备方法A kind of preparation method of nano-cellulose-starch film

技术领域technical field

本发明涉及膜材料技术领域，具体涉及一种纳米纤维素-淀粉膜的制备方法。The invention relates to the technical field of film materials, in particular to a preparation method of a nano-cellulose-starch film.

背景技术Background technique

一直以来，包装污染问题是世界各国都重点关注的焦点问题，近年来，随着技术的不断升级发展，生产出同时具备绿色安全、环保无毒害的包装膜已然成为食品保鲜包装领域研究的一个热点话题。这时淀粉基薄膜因其低廉的价格、原材料易于获取等诸多优点被大家关注，淀粉基薄膜不同于传统的塑料包装制品，对环境产生极大的污染，淀粉基薄膜具有绿色安全无毒、环保无污染、可降解等优点。这些优点使得淀粉基薄膜在包装产业获得了良好的应用前景。Packaging pollution has always been the focus of attention from all over the world. In recent years, with the continuous upgrading and development of technology, the production of packaging films that are both green, safe, environmentally friendly and non-toxic has become a hot spot in the field of food preservation packaging. topic. At this time, starch-based films have attracted attention because of their low price and easy access to raw materials. Starch-based films are different from traditional plastic packaging products, which cause great pollution to the environment. Starch-based films are green, safe, non-toxic and environmentally friendly. Non-polluting, degradable and other advantages. These advantages make starch-based films have good application prospects in the packaging industry.

纤维素作为目前世界上来源最广泛、资源最丰富的的天然高分子材料之一，植物纤维素因其优越的力学性能使得纤维素在植物细胞中充当骨架的作用，而且从植物中提取的纤维素具有众多优点，例如价格非常低廉，具备良好的生物相容性等等。CSNC(玉米秸秆纳米纤维素)既拥有植物纤维素的基本结构和功能，如：可持续性，可再生性，生物降解性等；又同时具有纳米粒子的一些特殊性质，如：高化学反应活性，高聚合度，高结晶度，高纯度，和高透明性等等。Cellulose is currently one of the most widely sourced and most abundant natural polymer materials in the world. Because of its superior mechanical properties, plant cellulose makes cellulose act as a skeleton in plant cells, and cellulose extracted from plants. It has many advantages, such as very low price, good biocompatibility and so on. CSNC (Corn Stalk Nanocellulose) not only has the basic structure and functions of plant cellulose, such as: sustainability, renewability, biodegradability, etc.; but also has some special properties of nanoparticles, such as: high chemical reactivity , high degree of polymerization, high crystallinity, high purity, and high transparency and so on.

超声波-微波协同处理其作用机理为微波辐射使得极性分子的高速运动，从而造成大分子氢键断裂的同时，加以超声波的高效振荡，使体系温度升高、加热更加均匀。与传统方法相比，超声波-微波协同处理具有众多优点，可以快速升温、很大程度上缩短反应的时间、节约能量、不会过多的损耗热能，以及具有提高效率、简单易操作、省时等等优点。The mechanism of ultrasonic-microwave synergistic treatment is that microwave radiation makes polar molecules move at a high speed, resulting in the rupture of macromolecular hydrogen bonds. Compared with traditional methods, ultrasonic-microwave co-processing has many advantages, such as rapid heating, greatly shortening the reaction time, saving energy, not losing too much heat energy, and improving efficiency, simple operation, and time saving. etc. advantages.

CN105196634A公开了一种层压法制备多层复合可食膜的方法，步骤包括：A、膜Ⅰ的制备：原料玉米磷酸酯淀粉或羧甲基淀粉、玉米秸秆纤维素和柠檬酸、甘油、羧甲基纤维素加入、蒸馏水中，搅拌、充分溶解，在超声-微波联合改性处理、真空脱气得到膜Ⅰ混合液。将膜Ⅰ混合液均匀涂布于有机玻璃成膜器内，制得膜Ⅰ备用。膜Ⅱ的制备：原料玉米醇溶蛋白、乙醇、羧甲基纤维素、甘油制得膜Ⅱ混合液。将膜Ⅱ混合液均匀涂布于有机玻璃成膜器内制得膜Ⅱ备用。膜Ⅰ、膜Ⅱ的复合：将膜Ⅱ平铺于膜Ⅰ表面，膜Ⅰ膜Ⅱ之间以膜Ⅰ混合液湿基为胶粘剂，经超声波-微波辅助层压复合，得到多层复合可食膜，其抗拉强度、断裂伸长率、阻湿性、阻气性明显提高。但是该方案中的多层复合膜其膜Ⅰ是淀粉基膜，膜Ⅱ是蛋白膜，淀粉基膜具有较好的机械强度，但是阻湿、阻气性能不好。蛋白膜可提高其阻湿、阻气性能，同时膜Ⅱ可使膜表面更加光滑、平整、美观。再经超声波-微波辅助层压复合工艺，使膜Ⅰ、膜Ⅱ紧密粘合，充分发挥膜Ⅰ和膜Ⅱ各自的优点，但是该方案制备过程复杂，而且在膜Ⅰ制备过程中采用的玉米变性淀粉，是经过二次加工后的改性淀粉，其成本增加。CN105196634A discloses a method for preparing multilayer composite edible film by lamination method, the steps include: A. Preparation of film I: raw material corn phosphate starch or carboxymethyl starch, corn stover cellulose and citric acid, glycerol, carboxylate Methyl cellulose is added into distilled water, stirred and fully dissolved, and is subjected to ultrasonic-microwave combined modification treatment and vacuum degassing to obtain a mixed solution of membrane I. The membrane I mixed solution is uniformly coated in a plexiglass film-forming device to prepare membrane I for use. Preparation of Membrane II: Membrane II mixed solution was prepared from raw material zein, ethanol, carboxymethyl cellulose and glycerol. The membrane II mixed solution was uniformly coated in a plexiglass film-forming device to prepare membrane II for later use. The composite of film I and film II: the film II is spread on the surface of film I, the film I mixed liquid wet base is used as the adhesive between the film I and the film II, and the multi-layer composite edible film is obtained by ultrasonic-microwave-assisted lamination and compounding. , its tensile strength, elongation at break, moisture resistance, and gas barrier properties are significantly improved. But the multi-layer composite film in this scheme has a starch-based film for film I and a protein film for film II. The starch-based film has good mechanical strength, but has poor moisture barrier and gas barrier properties. The protein membrane can improve its moisture and gas barrier properties, and the membrane II can make the membrane surface smoother, smoother and more beautiful. Then, through the ultrasonic-microwave-assisted lamination and composite process, the film I and the film II are tightly bonded, and the respective advantages of the film I and the film II are fully exerted. Starch is a modified starch after secondary processing, and its cost increases.

发明内容SUMMARY OF THE INVENTION

针对现有技术存在的上述不足，本发明的目的在于提供一种纳米纤维素-淀粉膜及其制备方法。In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a nanocellulose-starch film and a preparation method thereof.

为实现以上目的，本发明采用如下技术方案：To achieve the above purpose, the present invention adopts the following technical solutions:

一种纳米纤维素-淀粉膜的制备方法，包括以下步骤：A preparation method of nanocellulose-starch film, comprising the following steps:

1)将玉米秸秆淀粉溶解于蒸馏水中，糊化，随后加入玉米秸秆纳米纤维素，得到混合液Ⅰ；1) dissolving corn stalk starch in distilled water, gelatinizing, then adding corn stalk nanocellulose to obtain mixed solution I;

2)将羧甲基纤维素钠加入蒸馏水中，得到混合液Ⅱ，将混合液Ⅰ与混合液Ⅱ混合后进行搅拌，使羧甲基纤维素钠溶解后，加入甘油继续匀速搅拌，直至得到的膜液完全混合无明显颗粒，随后将膜液进行超声波-微波协同处理，待除去溶液气泡后将溶液流延于特制玻璃板上，制备得到纳米纤维素-淀粉膜。2) Add sodium carboxymethyl cellulose into distilled water to obtain mixed solution II, mix mixed solution I and mixed solution II and stir to dissolve sodium carboxymethyl cellulose, add glycerin and continue stirring at a constant speed until the obtained The film liquid is completely mixed without obvious particles, and then the film liquid is subjected to ultrasonic-microwave synergistic treatment. After the solution bubbles are removed, the solution is cast on a special glass plate to prepare a nanocellulose-starch film.

优选的，所述步骤1)中，糊化温度为70℃，糊化时间30分钟。Preferably, in the step 1), the gelatinization temperature is 70° C. and the gelatinization time is 30 minutes.

优选的，所述超声波-微波协同处理时间为15秒。Preferably, the ultrasonic-microwave co-processing time is 15 seconds.

优选的，在超声波-微波协同处理器中进行超声波-微波协同处理。Preferably, the ultrasonic-microwave co-processing is performed in an ultrasonic-microwave co-processor.

优选的，以重量份计，玉米秸秆淀粉为3份，玉米秸秆纳米纤维素为1.5份，羧甲基纤维素钠为0.48份，甘油为0.69份，步骤1)中蒸馏水为30份，步骤2)中蒸馏水为20份。Preferably, in parts by weight, corn stalk starch is 3 parts, corn stalk nanocellulose is 1.5 parts, sodium carboxymethyl cellulose is 0.48 parts, glycerol is 0.69 parts, distilled water in step 1) is 30 parts, step 2 ) is 20 parts of distilled water.

优选的，所述超声波-微波协同处理过程中，超声波功率为450W，微波功率为225W。Preferably, in the ultrasonic-microwave co-processing process, the ultrasonic power is 450W and the microwave power is 225W.

与现有技术相比，本发明具有以下有益效果：Compared with the prior art, the present invention has the following beneficial effects:

(1)本发明采用的纳米纤维素和淀粉，均来源于玉米秸秆废弃物，环保且节省成本；(1) Nanocellulose and starch adopted in the present invention are all derived from corn stalk waste, which is environmentally friendly and cost-saving;

(2)采用超声和微波对膜液进行处理，改善了膜的机械性能、阻湿性能、透气性能、透光性能和溶解性能，结构表征也显示其内部结构较为稳定。(2) Ultrasonic and microwave treatment of the membrane liquid improves the mechanical properties, moisture barrier properties, air permeability, light transmission properties and solubility properties of the membrane. The structural characterization also shows that its internal structure is relatively stable.

附图说明Description of drawings

通过阅读参照以下附图对非限制性实施例所作的详细描述，本发明的其它特征、目的和优点将会变得更明显：Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

图1为超声波-微波协同处理对膜机械指标的影响，其中a、b、c、d和e分别对应的微波功率为0W、75W、150W、225W和300W；Figure 1 shows the effect of ultrasonic-microwave synergistic treatment on the mechanical index of the membrane, wherein the microwave powers corresponding to a, b, c, d and e are 0W, 75W, 150W, 225W and 300W respectively;

图2为超声波-微波协同作用对膜透湿性的影响；Figure 2 shows the effect of ultrasonic-microwave synergy on the moisture permeability of membranes;

图3为超声波-微波协同作用对膜透光性的影响；Figure 3 shows the effect of ultrasonic-microwave synergy on the light transmittance of the film;

图4为超声波-微波协同作用对膜溶解时间的影响；Figure 4 shows the effect of ultrasonic-microwave synergy on the dissolution time of the membrane;

图5为超声波-微波协同作用对膜透氧量的影响；Figure 5 shows the effect of ultrasonic-microwave synergy on membrane oxygen permeability;

图6为超声波-微波协同处理前后膜的电镜图，其中a为未经超声波-微波处理的膜表面(×1500)，b为经超声波-微波改性处理的膜表面(×1500)。Figure 6 shows the electron microscope images of the membrane before and after ultrasonic-microwave synergistic treatment, wherein a is the surface of the membrane without ultrasonic-microwave treatment (×1500), and b is the surface of the membrane modified by ultrasonic-microwave treatment (×1500).

具体实施方式Detailed ways

下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明，但不以任何形式限制本发明。应当指出的是，对本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进。这些都属于本发明的保护范围。The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

实施例1Example 1

材料和试剂：Materials and Reagents:

CSNC(玉米秸秆纳米纤维素)、CSS(玉米秸秆淀粉)：自制；羧甲基纤维素钠：分析纯，天津市大茂化学试剂厂；甘油：分析纯，上海麦克林生化科技有限公司。CSNC (corn stalk nanocellulose), CSS (corn stalk starch): self-made; sodium carboxymethyl cellulose: analytical grade, Tianjin Damao Chemical Reagent Factory; glycerin: analytical grade, Shanghai McLean Biochemical Technology Co., Ltd.

仪器与设备：Instruments and Equipment:

JJ-1精密定时电动搅拌器：江苏金坛市荣华仪器厂；79-1磁力加热搅拌器：金坛市虹盛仪器厂；DGG-9140B电热恒温鼓风干燥箱：上海森信实验仪器厂；JD100-3B电子天平：沈阳龙腾电子有限公司；XLW智能电子拉力试验机：济南兰光机电技术有限公司；WGT-S透光/雾度测定仪：上海仪电物理光学仪器有限公司；TSY-T1H透湿性测试仪：济南兰光机电技术有限公司。JJ-1 Precision Timing Electric Stirrer: Jiangsu Jintan Ronghua Instrument Factory; 79-1 Magnetic Heating Stirrer: Jintan Hongsheng Instrument Factory; DGG-9140B Electric Heating Constant Temperature Blast Drying Oven: Shanghai Senxin Experimental Instrument Factory; JD100-3B Electronic Balance: Shenyang Longteng Electronics Co., Ltd.; XLW Intelligent Electronic Tensile Testing Machine: Jinan Languang Electromechanical Technology Co., Ltd.; WGT-S Transmittance/Haze Tester: Shanghai INESA Physical Optical Instrument Co., Ltd.; TSY-T1H Moisture permeability tester: Jinan Languang Electromechanical Technology Co., Ltd.

CSNC-CSS膜的制备：Preparation of CSNC-CSS membranes:

1)称取一定量自制的CSS溶解于30mL蒸馏水中，70℃糊化30min，随后称取适量自制的CSNC加入瓶中，记为瓶1，放置备用；1) Weigh a certain amount of self-made CSS and dissolve it in 30 mL of distilled water, gelatinize at 70° C. for 30 min, then weigh an appropriate amount of self-made CSNC and add it to the bottle, denoted asbottle 1, and place it for later use;

2)称取20mL蒸馏水放置于瓶2中，缓缓加入适量的羧甲基纤维素钠，磁力搅拌8min使其溶解，混合瓶1与瓶2中的溶液，匀速搅拌20min后，加入甘油继续匀速搅拌10min，直至瓶内膜液完全混合无明显颗粒，随后将CSNC-CSS膜液放置于超声波-微波协同处理器(可以使用超声波-微波协同萃取仪)中进行实验，超声波-微波协同改性条件见表1，待除去溶液气泡后将溶液流延于特制玻璃板上，待凝固后，放于35℃电热烘干箱中8h，干燥后取出。按上述相同操作制备未经超声波-微波协同处理的CSNC-CSS膜，备用。2) Weigh 20 mL of distilled water and place it in bottle 2, slowly add an appropriate amount of sodium carboxymethyl cellulose, stir magnetically for 8 minutes to dissolve, mix the solutions inbottle 1 and bottle 2, stir at a constant speed for 20 minutes, add glycerin and continue at a constant speed Stir for 10 minutes until the membrane liquid in the bottle is completely mixed without obvious particles, and then place the CSNC-CSS membrane liquid in an ultrasonic-microwave co-processor (ultrasonic-microwave co-extractor can be used) for experiments. The ultrasonic-microwave co-modification conditions See Table 1. After the solution bubbles are removed, the solution is cast on a special glass plate. After solidification, it is placed in an electric heating drying box at 35°C for 8 hours, and taken out after drying. The CSNC-CSS film without ultrasonic-microwave co-treatment was prepared by the same operation as above, and it was used for later use.

表1超声波-微波协同改性条件Table 1 Ultrasonic-microwave synergistic modification conditions

实验结果分析：Analysis of results:

(1)超声波-微波处理对CSNC-CSS膜机械性能的影响(1) Effect of ultrasonic-microwave treatment on mechanical properties of CSNC-CSS membranes

抗拉强度和断裂伸长率是判定复合膜是否能承受外部压力的重要质构参数，超声波-微波协同处理对CSNC-CSS膜机械性能的影响如图1所示。由图可知，未经超声波-微波处理的CSNC-CSS膜抗拉强度和断裂伸长率分别为14.35MPa和61.50％。经超声波-微波处理后，由于超声波处理产生的超混合作用及空化作用，使CSNC-CSS膜液中的分子发生剧烈地碰撞，剧烈地碰撞不仅加强了内容物之间的相互作用，减小了分子的粒径，增大了比表面积。还进而断裂了膜液中的化学键，导致膜液中氢键的数量不断扩大。所以当微波功率为0W时，超声功率从0W增加到600W时，抗拉强度逐渐增加，这是因为此时的处理条件有利于构建致密的复合膜结构，CSNC-CSS膜的空间结构稳定性能得到了提升，导致抗拉强度增加。经过超声波-微波协同处理后，CSNC-CSS膜液中淀粉链被破坏致使释放出直链淀粉，导致直链淀粉的比例增加，这使得CSNC-CSS膜的抗拉性能得到提升。使膜获得了更大的抗拉强度。但是随着超声波功率的升高，CSNC-CSS膜的断裂伸长率呈现先增加后降低的趋势，证明了适当得超声功率可以有效地改善膜的断裂伸长率，但当超声波功率过高时，超混合作用的不断增加，已经超过了CSNC-CSS膜的临界的承受值，损坏了膜液中共聚物之间的稳定结构，影响了复合膜的韧性，导致CSNC-CSS膜的抗拉强度与断裂伸长率均呈现降低的趋势。Tensile strength and elongation at break are important texture parameters to determine whether the composite film can withstand external pressure. The effect of ultrasonic-microwave co-processing on the mechanical properties of CSNC-CSS film is shown in Figure 1. It can be seen from the figure that the tensile strength and elongation at break of the CSNC-CSS film without ultrasonic-microwave treatment are 14.35MPa and 61.50%, respectively. After ultrasonic-microwave treatment, due to the supermixing effect and cavitation produced by ultrasonic treatment, the molecules in the CSNC-CSS membrane fluid collide violently. The violent collision not only strengthens the interaction between the contents, but also reduces the The particle size of the molecule is increased, and the specific surface area is increased. Furthermore, the chemical bonds in the membrane liquid are broken, resulting in the continuous expansion of the number of hydrogen bonds in the membrane liquid. Therefore, when the microwave power is 0W and the ultrasonic power increases from 0W to 600W, the tensile strength gradually increases. This is because the processing conditions at this time are conducive to the construction of a dense composite film structure, and the spatial structure stability of the CSNC-CSS film can be obtained. increased, resulting in an increase in tensile strength. After ultrasonic-microwave synergistic treatment, the starch chains in the CSNC-CSS membrane solution were destroyed, resulting in the release of amylose, resulting in an increase in the proportion of amylose, which improved the tensile properties of the CSNC-CSS membrane. The film obtains greater tensile strength. However, with the increase of ultrasonic power, the elongation at break of CSNC-CSS film showed a trend of increasing first and then decreasing, which proved that appropriate ultrasonic power can effectively improve the elongation at break of the film, but when the ultrasonic power was too high , the continuous increase of the supermixing effect has exceeded the critical bearing value of the CSNC-CSS film, damaged the stable structure between the copolymers in the film liquid, affected the toughness of the composite film, and resulted in the tensile strength of the CSNC-CSS film. and elongation at break showed a decreasing trend.

当微波功率分别为50W、100W、150W、200W时，随着超声波功率的升高，CSNC-CSS膜的抗拉强度呈现先增加后降低的趋势，这是由于超声波-微波协同处理可以减小膜液微粒的尺寸，同时增大了颗粒的表面积。CSNC-CSS膜的机械性能与膜液中的各个分子的尺寸、结构，以及膜液分子间非共价键的作用都有关联。此外，由于超声波-微波处理的超混合作用加快了膜液分子之间的运动速度，增强了膜液分子在基质中的相互作用。超声微波协同处理利用了微波辐射，使极性分子产生高速地运动从而造成大分子氢键的断裂，同时，超声波的高效振荡作用使得反应体系被均匀加热，超声波-微波处理产生的热量使得膜液中内容物的溶解性能有效提高，形成的致密的网络结构使CSNC-CSS膜的抗拉强度得到提升，当微波功率为300W时，断裂伸长率呈现下降的趋势，这是因为随着超声波功率的增加，超声波的空化作用与超混合作用接近于饱和状态，破坏了其内部稳定的结构，降低了复合膜内的内聚力，导致可食膜机械性能下降。可见，通过适宜的超声-微波协同处理可以增强膜的抗拉强度与断裂伸长率。When the microwave power was 50W, 100W, 150W, and 200W, respectively, with the increase of ultrasonic power, the tensile strength of CSNC-CSS film increased first and then decreased. The size of the liquid particles, while increasing the surface area of the particles. The mechanical properties of CSNC-CSS membranes are related to the size and structure of each molecule in the membrane liquid, as well as the role of non-covalent bonds between the membrane liquid molecules. In addition, due to the super-mixing effect of ultrasonic-microwave treatment, the movement speed between the membrane liquid molecules is accelerated, and the interaction of the membrane liquid molecules in the matrix is enhanced. Ultrasonic-microwave synergistic treatment utilizes microwave radiation to make polar molecules move at high speed, resulting in the breaking of macromolecular hydrogen bonds. At the same time, the high-efficiency oscillation of ultrasonic waves makes the reaction system uniformly heated, and the heat generated by ultrasonic-microwave treatment makes the membrane liquid The dissolution performance of the content in the medium is effectively improved, and the formed dense network structure improves the tensile strength of the CSNC-CSS film. When the microwave power is 300W, the elongation at break shows a decreasing trend. This is because with the ultrasonic power With the increase of , the cavitation and supermixing effects of ultrasonic waves are close to a saturated state, which destroys its internal stable structure, reduces the cohesion in the composite film, and leads to a decline in the mechanical properties of the edible film. It can be seen that the tensile strength and elongation at break of the film can be enhanced by suitable ultrasonic-microwave synergistic treatment.

(2)超声波-微波处理对CSNC-CSS膜透湿性能的影响(2) Effect of ultrasonic-microwave treatment on moisture permeability of CSNC-CSS membrane

复合膜的透湿性可以有效反应出复合膜对水蒸气的阻隔能力的强弱，阻隔水蒸气的能力也是判断包装材料优劣性的重要指标之一。透湿系数越小，证明膜的阻隔水分子的性能越好。超声功率和微波功率对透湿性能有影响，是因为超声波-微波处理影响了膜内分子的分子聚集结构，超声波-微波作用产生了强大的机械作用以及空化作用，同时伴随着热作用的生成，这使得大部分的CSS的结构遭到了破坏，导致直链淀粉在膜液中的比重增加，增大了复合膜的阻隔性。由图2可知，CSNC-CSS膜的透湿性随着超声波功率和微波功率的增加而逐渐降低，当超声波功率为600W，微波功率为225W时，薄膜的透湿量达到最低值1.97×(10^-12g·m/m²·s·Pa)，这是由于超声波-微波协同作用增强了超声空化效应，有效改善了CSNC-CSS膜分子间的聚集结构和致密程度，同时，淀粉链和化学键被打断，CSNC-CSS膜分子间的相互作用力增强致使分子间的结构变得紧密有序，导致透湿性降低。当超声波功率和微波功率增加到一定水平时，CSNC-CSS膜的阻水性能下降，透湿性将不再降低。The moisture permeability of the composite film can effectively reflect the strength of the composite film's ability to block water vapor, and the ability to block water vapor is also one of the important indicators for judging the quality of packaging materials. The smaller the moisture permeability coefficient, the better the performance of the membrane to block water molecules. Ultrasonic power and microwave power have an impact on the moisture permeability, because the ultrasonic-microwave treatment affects the molecular aggregation structure of the molecules in the membrane, and the ultrasonic-microwave action produces a strong mechanical action and cavitation, which is accompanied by the generation of thermal action. , which destroys most of the CSS structure, resulting in an increase in the specific gravity of amylose in the membrane liquid, which increases the barrier properties of the composite membrane. It can be seen from Figure 2 that the moisture permeability of CSNC-CSS film gradually decreases with the increase of ultrasonic power and microwave power. When the ultrasonic power is 600W and the microwave power is 225W, the moisture permeability of the film reaches the lowest value of 1.97×(10^{− 12} g·m/m² ·s·Pa), which is due to the synergistic effect of ultrasonic-microwave to enhance the ultrasonic cavitation effect, which effectively improves the intermolecular aggregation structure and compactness of CSNC-CSS membranes. At the same time, starch chains and chemical bonds When interrupted, the intermolecular interaction force of CSNC-CSS membrane is enhanced, resulting in the intermolecular structure becoming compact and orderly, resulting in a decrease in moisture permeability. When the ultrasonic power and microwave power increased to a certain level, the water blocking performance of the CSNC-CSS film decreased, and the moisture permeability would no longer decrease.

(3)超声波-微波处理对CSNC-CSS膜透光性能的影响(3) Influence of ultrasonic-microwave treatment on light transmittance of CSNC-CSS film

当膜液中聚合物的相容性差时，透光率就会降低，由图3可知，在适宜的超声波功率和微波功率条件下，可以增强CSNC-CSS膜的透光性能。当微波功率为0W时，随着超声波功率的不断增加，透光率呈增加趋势，当超声波功率为600W，微波功率为300W时，透光率达到最低值80.5％，这是因为超声波-微波所产生的空化作用使膜液官能团的化学键被破坏了，从而导致CSNC、CSS的尺寸减小。同时，由于超声波作用使膜液脱气，光反射损失较小。但是随着微波功率的不断增大，CSNC-CSS膜的透光率呈现先增加后降低的趋势，这是因为适宜的超声波-微波处理可以提高膜液分子间的相容性，使成膜液中的粒子分散的更均匀，流延成膜后的CSNC-CSS膜表面相对更加光滑，没有颗粒和孔洞，所以透光率增加。When the compatibility of the polymer in the film liquid is poor, the light transmittance will decrease. It can be seen from Figure 3 that the light transmittance of the CSNC-CSS film can be enhanced under suitable ultrasonic power and microwave power conditions. When the microwave power is 0W, with the continuous increase of the ultrasonic power, the light transmittance shows an increasing trend. When the ultrasonic power is 600W and the microwave power is 300W, the light transmittance reaches the lowest value of 80.5%. This is because the ultrasonic-microwave The resulting cavitation breaks the chemical bonds of the functional groups in the membrane liquid, resulting in the size reduction of CSNC and CSS. At the same time, due to the degassing of the film liquid by the action of ultrasonic waves, the light reflection loss is small. However, with the continuous increase of microwave power, the transmittance of CSNC-CSS film showed a trend of increasing first and then decreasing. The particles in the film are more uniformly dispersed, and the surface of the CSNC-CSS film after casting is relatively smoother, without particles and holes, so the light transmittance is increased.

(4)超声波-微波处理对CSNC-CSS膜溶解性能的影响(4) Effect of ultrasonic-microwave treatment on the solubility of CSNC-CSS membranes

由图4可知，在微波功率为0W时，随着超声波功率的持续增加，可食膜的水溶性增高，这是因为超声波的空化作用使CSNC-CSS膜中的CSS与CSNC的尺寸减小，并使CSS与CSNC的比表面积增大，CSS与CSNC的结构强度降低，促使了水分子和CSS分子中游离羟基的结合，提高了CSNC-CSS膜的致密性，提高了CSNC-CSS膜的溶解度，缩短了溶解时间。It can be seen from Figure 4 that when the microwave power is 0W, with the continuous increase of the ultrasonic power, the water solubility of the edible film increases, because the cavitation of the ultrasonic wave reduces the size of CSS and CSNC in the CSNC-CSS film. , which increases the specific surface area of CSS and CSNC, and reduces the structural strength of CSS and CSNC, which promotes the combination of water molecules and free hydroxyl groups in CSS molecules, improves the compactness of CSNC-CSS film, and improves the strength of CSNC-CSS film. Solubility and shortened dissolution time.

(5)超声波-微波处理对CSNC-CSS膜透氧性能的影响(5) Effect of ultrasonic-microwave treatment on oxygen permeability of CSNC-CSS membrane

由图5可知，在微波功率不变的条件下，随着超声波功率的持续增大，CSNC-CSS膜的透氧量呈现先增高后降低的趋势，这是由于超声波功率的持续增大，超声波-微波协同处理产生了更强的空化作用和超混合作用，膜液分子间的化学键被打断导致更多的极性基团被暴露出来。同时超声波-微波协同处理产生的热作用使膜液中的粒子混合地更加均匀，形成更加致密的网状结构，有效阻碍了O₂分子的透过，提高了CSNC-CSS膜的阻氧性能。而且经过超声波-微波处理后，导致了更多反应中心的形成与暴露，进而增加了化学反应的速率，而膜液中大分子之间的重新排列、结合又使得CSNC-CSS膜的网状结构更加紧密地结合在一起，阻气性增强。但继续增大超声波功率和微波功率，会导致分子中的部分化学键被过度地打断，而微波处理的加热效应持续增强，这使得自由基不能有效结合，而是形成了无序的分子间结构，导致间隙增大，CSNC-CSS膜的阻氧性能下降。It can be seen from Fig. 5 that under the condition of constant microwave power, with the continuous increase of ultrasonic power, the oxygen permeability of CSNC-CSS film increases first and then decreases. - The microwave synergistic treatment produces stronger cavitation and supermixing, and the chemical bonds between the molecules of the membrane liquid are broken and more polar groups are exposed. At the same time, the heat generated by the ultrasonic-microwave synergistic treatment makes the particles in the film liquid mix more uniformly, forming a denser network structure, which effectively hinders the penetration of O molecules and improves the oxygen barrier performance of the CSNC_- CSS film. Moreover, after ultrasonic-microwave treatment, more reaction centers are formed and exposed, which in turn increases the rate of chemical reaction, and the rearrangement and combination of macromolecules in the membrane liquid make the network structure of CSNC-CSS membrane. It is more tightly combined, and the gas barrier is enhanced. However, continuing to increase the ultrasonic power and microwave power will cause some chemical bonds in the molecules to be excessively broken, and the heating effect of the microwave treatment continues to increase, which makes the free radicals unable to combine effectively, but forms a disordered intermolecular structure. , resulting in an increase in the gap and a decrease in the oxygen barrier properties of the CSNC-CSS film.

(6)扫描电镜分析(6) Scanning electron microscope analysis

通过电镜扫描图可以清晰的观察到CSNC-CSS膜体系内各相的分散状态以及相界面之间的结合情况，膜内的内容物相容的情况下，膜的表面将十分光滑、均匀；反之膜内的内容物不相容或不完全相容的情况下，膜的表面将会出现突起颗粒和分明的相界面。由图6可知，未经超声波-微波协同处理的CSNC-CSS膜表面粗糙，横截面松散；经处理后的CSNC-CSS膜表面更加平滑、平坦，质地均匀，没有明显的突起颗粒和破碎的孔洞，这是因为经过超声波-微波处理的CSNC-CSS膜中CSS与CSNC分子之间交联作用增强，形成了更多的分子间氢键，共混体系的相容性被进一步提高。The dispersion state of each phase in the CSNC-CSS film system and the bonding between the phase interfaces can be clearly observed through the scanning electron microscope. When the contents in the film are compatible, the surface of the film will be very smooth and uniform; otherwise When the contents of the film are incompatible or not completely compatible, protruding particles and distinct phase interfaces will appear on the surface of the film. It can be seen from Figure 6 that the surface of the CSNC-CSS film without ultrasonic-microwave synergistic treatment is rough and the cross section is loose; the surface of the CSNC-CSS film after treatment is smoother, flat, and uniform in texture, without obvious protruding particles and broken holes. , this is because the cross-linking between CSS and CSNC molecules in the CSNC-CSS film treated by ultrasonic-microwave is enhanced, more intermolecular hydrogen bonds are formed, and the compatibility of the blend system is further improved.

(7)对比分析(7) Comparative analysis

现将经过超声波-微波处理的CSNC-CSS膜与未经超声波-微波处理的CSNC-CSS膜进行对比，得到对比结果如表2所示。Now, the CSNC-CSS film treated with ultrasonic-microwave is compared with the CSNC-CSS film without ultrasonic-microwave treatment, and the comparison results are shown in Table 2.

表2未经超声-微波处理和经超声-微波处理淀粉膜性能对比结果Table 2 Comparison results of properties of starch films without ultrasonic-microwave treatment and those treated with ultrasonic-microwave

以重量份计，由玉米秸秆淀粉3份，玉米秸秆纳米纤维素1.5份，羧甲基纤维素钠0.48份，甘油0.69份，步骤1)中蒸馏水30份，步骤2)中蒸馏水20份制备CSNC-CSS膜。由表2可知，经过超声波-微波处理(超声波功率为450W，微波功率为225W)的CSNC-CSS膜较未经超声波-微波处理的CSNC-CSS膜各个指标性能均有提升，其中，抗拉强度由15.25MPa提升到23.85MPa，提高了56.40％；断裂伸长率由原始的63.20％提高至90.08％，提高了42.50％；经过超声波-微波处理，透湿性、透光量、溶解时间和透氧率均有所下降，分别下降了14.1％、3.8％、17.9％、56.7％。试验证明，经超声波功率450W，微波功率225W处理后的CSNC-CSS膜具有更好的机械性能、阻湿性能、阻气性能，具有广泛的应用前景。In parts by weight, CSNC is prepared from 3 parts of corn stalk starch, 1.5 parts of corn stalk nanocellulose, 0.48 parts of sodium carboxymethyl cellulose, 0.69 parts of glycerin, 30 parts of distilled water in step 1), and 20 parts of distilled water in step 2). -CSS membrane. It can be seen from Table 2 that the CSNC-CSS film after ultrasonic-microwave treatment (ultrasonic power is 450W, microwave power is 225W) has improved performance in each index compared with the CSNC-CSS film without ultrasonic-microwave treatment. Among them, tensile strength From 15.25MPa to 23.85MPa, an increase of 56.40%; the elongation at break increased from the original 63.20% to 90.08%, an increase of 42.50%; after ultrasonic-microwave treatment, the moisture permeability, light transmission, dissolution time and oxygen permeability The rates have all declined by 14.1%, 3.8%, 17.9% and 56.7% respectively. Experiments show that the CSNC-CSS film treated with ultrasonic power of 450W and microwave power of 225W has better mechanical properties, moisture barrier properties and gas barrier properties, and has a wide range of application prospects.

本实施例中膜性能的测定方法如下：The measuring method of film performance in the present embodiment is as follows:

机械性能测定：参考GB/T 1040.3-2006“薄塑和薄片的拉伸性能测试标准方法”，设定测量条件(膜长为150mm、宽为20mm，初始夹距为50mm，拉引速率设为25mm/min)。5次平行测定，取平均值。Determination of mechanical properties: refer to GB/T 1040.3-2006 "Standard Method for Testing Tensile Properties of Thin Plastics and Sheets", and set the measurement conditions (film length is 150mm, width is 20mm, initial clamping distance is 50mm, and the pulling rate is set to 25mm/min). 5 parallel determinations were made, and the average value was taken.

透湿性测定：参考GB/T 16928-1997“包装材料试验方法-透湿率”标准方法。5次平行测定，取平均值。Determination of moisture permeability: refer to the standard method of GB/T 16928-1997 "Test method for packaging materials - moisture permeability". 5 parallel determinations were made, and the average value was taken.

透光率测定：参考GB/T 2410-80-2008“透明塑料透光率和雾度的测定”，5次平行测定，取平均值。Measurement of light transmittance: refer to GB/T 2410-80-2008 "Determination of light transmittance and haze of transparent plastics", 5 parallel measurements, and take the average value.

水溶性测定：通过对薄膜在常温蒸馏水中的溶解时间的测定进而评定其水溶性。将制备的薄膜剪成5×5的正方形，置于100mL，80℃蒸馏水中，磁力搅拌器搅拌，测定CSNC-CSS膜在水中的完全溶解时间。5次平行测定，取平均值。Determination of water solubility: The water solubility of the film was evaluated by measuring the dissolution time of the film in distilled water at room temperature. The prepared film was cut into a 5×5 square, placed in 100 mL of distilled water at 80°C, stirred with a magnetic stirrer, and the complete dissolution time of the CSNC-CSS film in water was measured. 5 parallel determinations were made, and the average value was taken.

透气量的测定：参考GB/T1038-2000“塑料薄膜和薄片气体透过性试验方法”压差法，对抗菌膜的透O₂系数进行测试，膜的直径为85mm测量5次取平均值。Determination of air permeability: referring to GB/T1038-2000 "Test method for gas permeability of plastic films and sheets", the pressure difference method is used to test the_O2 permeability coefficient of the antibacterial film. The diameter of the film is 85mm and the average value is obtained by measuring 5 times.

以上对本发明的具体实施例进行了描述。需要理解的是，本发明并不局限于上述特定实施方式，本领域技术人员可以在权利要求的范围内做出各种变形或修改，这并不影响本发明的实质内容。Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various variations or modifications within the scope of the claims, which do not affect the essential content of the present invention.

Claims (6)

1. The preparation method of the nano-cellulose-starch film is characterized by comprising the following steps:

1) dissolving corn stalk starch in distilled water, gelatinizing, and adding corn stalk nano cellulose to obtain a mixed solution I;

2) adding sodium carboxymethylcellulose into distilled water, dissolving the sodium carboxymethylcellulose to obtain a mixed solution II, mixing the mixed solution I and the mixed solution II, stirring, adding glycerol, continuously stirring at a constant speed until the obtained membrane solution is completely mixed without obvious particles, then performing ultrasonic-microwave synergistic treatment on the membrane solution, and casting the solution on a special glass plate after removing bubbles of the solution to prepare the nano-cellulose-starch membrane.

2. The method for preparing a nano cellulose-starch film according to claim 1, wherein the gelatinization temperature in the step 1) is 70 ℃ and the gelatinization time is 30 minutes.

3. The method for preparing a nano-cellulose-starch film according to claim 1, wherein the ultrasonic-microwave synergistic treatment time is 15 seconds.

4. The method of claim 1, wherein the ultrasonic-microwave co-treatment is performed in an ultrasonic-microwave co-processor.

5. The method for preparing the nano-cellulose-starch film according to claim 1, wherein the weight parts of the corn stalk starch are 3 parts, the corn stalk nano-cellulose is 1.5 parts, the sodium carboxymethyl cellulose is 0.48 part, the glycerol is 0.69 part, the distilled water in the step 1) is 30 parts, and the distilled water in the step 2) is 20 parts.

6. The method for preparing the nano-cellulose-starch film according to claim 1, wherein the ultrasonic power is 450W and the microwave power is 225W during the ultrasonic-microwave synergistic treatment.

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