# Metal Cellulose Nanocomposites in Decorative Animation Character Modeling

Authors: Lili Zhang
Journal: Advances in Materials Science and Engineering
 (2022)

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## Abstract

With the development of economy, people’s research on nanomaterials has become more and more, and nanomaterials can be applied in many fields, such as medicine and building materials. The animation character modeling is very important in the cartoon, and the decoration of the animation character modeling can help improve people’s interest in watching cartoons and improve the quality of cartoons. This paper aims to study the role of metal cellulose nanocomposites in the modeling of decorative animation characters. In this paper, the principles and basic concepts of metal cellulose nanocomposites are presented, as well as the analysis of their properties. The experimental results in this paper show that the adsorption of copper in cellulose nanocomposites reaches 256.28 mg/g, the adsorption of chromium is 40.73 mg/g, and the adsorption of cadmium is 47.20 mg/g. The adsorption of other materials to copper is only 80.44 mg/g, the adsorption of chromium (VI) is only 1.116 mg/g, and the adsorption of cadmium is only 9.487 mg/g. It can be seen that the adsorption capacity of cellulose nanocomposites is much higher than that of other materials, so the adsorption properties of cellulose nanocomposites are very strong and can be applied in many fields.


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## Body

## 1. Introduction

Cartoons can satisfy people’s thirst for knowledge, and their curiosity and interest will grow. In watching cartoons, we can find answers to many questions, and the answers are very vivid, easy to accept, and impressive. Animation character modeling is the artistic production of the modeling and character performance of all characters in animation works. The animation character design and art style are combined to get the animation character shape. Combined with the character’s personality, the storyline is explained, the progress of the plot is promoted, and the fate of the animated character is clarified. The decoration of animation character modeling refers to the setting of characters’ images, costumes, and small props in comics, which can fully display the characteristics of each character and meet the requirements of animation production.Colors and materials in animated character modeling must be perceived visually, and the symbolization of graphics is most easily recognized by human vision in volumes, materials, and colors, because animation is a work of art presented in general. Depending on the type, animation character modeling needs to organize the original impression of the world and properly decorate and symbolize the character modeling, so as to keep up with the trend of the times. This is an effective artistic treatment.The innovations of this paper are as follows:(1)
This paper introduces the theoretical knowledge of metal cellulose nanocomposites and decorative animation character modeling and focuses on the concept, preparation methods, and characteristics of metal cellulose nanocomposites.(2)
This paper summarizes the importance of metal cellulose nanocomposites and decorative animation character modeling. It is found through experiments that metal cellulose nanocomposites can promote the development of decorative animation character modeling.


## 2. Related Work

Animation’s production process has experienced significant changes as a result of the in-depth development of computer network technology, as well as the popularization and application of computers. The Virtual Human Toolkit was extended by Hartholt to cover a variety of computing platforms, including mobile, web, virtual reality (VR), and augmented reality (AR). He describes the framework’s current status, how to model and animate characters, and lessons learned from a variety of use cases involving motion sensors in headset AR for real-time user performance feedback. Although Hartholt discovered computer modeling and the problems involved, the scholar did not specify what the lessons learned were [1]. Woodward found that 3D expression modeling provides a robust and low-cost framework that uses off-the-shelf stereo webcams, has low computational requirements, runs on standard hardware, and is portable. It does not require a controlled laboratory environment and is very stable under a variety of conditions. Stereo webcams perform 3D marker tracking to obtain nonrigid motion images of head rigid motion and expressions, and then map the tracked markers onto a 3D facial model with a virtual muscle animation system. However, the scholar did not explain the whole process of the experiment, nor did he draw specific conclusions [2]. Zhang F found that virtual reality (VR) is usually achieved using the realistic effects of animation, such as special effects in movies and so on. But this resulted in a particularly high computational cost. To solve this problem, he devised a fast tool to accelerate and simulate fluid animations and applied some GPU optimization strategies to parallel systems according to the characteristics of the hardware. Then, he designs an optimized parallel framework for higher performance. Although the scholar designed a corresponding framework for the problem, he did not explain why the framework can achieve higher performance [3]. Ghasemi discovered that cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) can be used to improve the mechanical properties of yarns produced from natural fibers. CNC, unmilled CNF, and two different milled CNF suspensions were also added to the enhancer. The results of his study show that both the initial modulus and the strength of flax fibers are improved after soaking in nanocellulose suspensions, especially when using CNF. Although the scholar explained the process and objects of the experiment, he did not explain the data of the experiment [4]. Choudhury found that bioderived nanocelluloses possess a variety of properties that make them highly desirable for advanced functional applications. Nanocellulose, that is, nanofibers and nanocrystals, can be applied in nanocomposites, coatings, and films in the form of solutions, suspensions, inks, or nanomaterials. These forms of nanocellulose can be used to develop hydrogels, adsorbents, and biomaterials for biomedicine and tissue engineering, and he reviews the extraction of nanocellulose and its properties. Although the scholar described the application field of nanocellulose, he did not explain the extraction process and discovered properties of nanocellulose [5]. Ewulonu found that sustainable functional materials have environmental protection functions, so there is an increasing demand for this material. Lignocellulose is the most sustainable biological resource on Earth, but the production process of lignocellulose is very difficult. Therefore, his focus is to discuss the preparation process, properties, and applications of this novel lignocellulose-containing nanomaterial to draw a sustainable route for cellulose preparation. However, the scholar did not elaborate what the sustainable preparation route he drew was [6].


## 3. Properties of Metal Cellulose Nanocomposites

There are highly regular crystalline regions in the supramolecular structure of natural cellulose, and the strong hydrogen bonds between microfibrils make cellulose difficult to dissolve in most common solvents. The molecular formula of cellulose is (C6H10O5)n; n is the degree of polymerization, and the molecular weight is between 5 × 103 and 2.5 × 106. Its structure is shown in Figure 1.Figure 1
Molecular structure of cellulose.As shown in Figure1, cellulose has many free active hydroxyl groups, which are formed by the hydrogen bonds between most of the free hydroxyl groups, and most of the hydrogen bonds between the cellulose molecules form a network structure to strengthen the cellulose molecules [7]. Hydroxyl radical (OH) is an important reactive oxygen species, which is formed by the loss of an electron from hydroxide (OH-), and it is the oxidant second only to fluorine in nature.


### 3.1. Nanocellulose and Preparation Method

Nanocellulose material is a new type of nanoscale biodegradable material with large specific surface area, high Young’s modulus, high adsorption performance, and high reactivity. It is a nanocellulose material with a high aspect ratio in the crystalline field [8]. Nanofiber refers to a wire-like material with a diameter of nanometer scale and a large length with a certain aspect ratio. In addition, the fibers that are modified by filling nanoparticles into ordinary fibers are also called nanofibers. Nanocellulose materials made of nanocellulose films and nanocellulose are widely used in chemical industry, materials, food, medicine, and other fields [9].The classification according to the preparation method and size of cellulose is shown in Table1.Table 1
Classification of nanocellulose.
namePreparationLength (nm)Diameter (nm)Cellulose nanocrystalsChemical method15020Cellulose nanofibersPhysical law100218Bacterial celluloseBiological law10026As shown in Table1, nanocellulose reaches nanoscale dimensions in at least one dimension, and its properties are quite different from those of pristine cellulose. Studies have shown that the proportion of crystallinity domains can be increased through a series of mechanical, chemical, and biological methods that destroy the structure of natural cellulose amorphous domains [10].


#### 3.1.1. Preparation of Cellulose Nanofibers by Mechanical Method

Mechanical methods include various physical and mechanical treatment methods such as strong shearing, pulverization, high-pressure equalization, microfluidics, and high-density ultrasound [11]. High pressure homogenizer is also called “high pressure fluid nano homogenizer.” It can make the material in the state of suspension flow through the cavity with special internal structure at high speed under the action of ultrahigh pressure (up to 60000psi), so that the material undergoes a series of changes in physical, chemical, and structural properties, etc., and finally achieves homogeneity effect. The preparation of microspheres of cellulose by high pressure homogenization is mainly carried out through the coaxial homogenization valve in the homogenizer. The schematic diagram of the structure of a typical high-pressure homogenizer is shown in Figure 2.Figure 2
Schematic diagram of the structure of a typical high-pressure homogenizer.As shown in Figure2, if the regulating valve is opened and closed continuously, a cavitation effect will occur, and the raw cellulose collides at high speed through cavitation, so that the cellulose fibers are gradually separated, and microfibrillated cellulose is gradually obtained [12].


#### 3.1.2. Preparation of Nanocellulose Crystals by Acid Hydrolysis

Nanocellulose crystals are prepared by acid hydrolysis, and strong acid is used to destroy the amorphous regions of the cellulose structure, so that they maintain neatly arranged high-density crystalline regions [13]. Acidified hydrolysis generally refers to hydrolytic acidification. The hydrolysis treatment method is a method between the aerobic and the anaerobic treatment methods, and the combination of other processes can reduce the treatment cost and improve the treatment efficiency. Hydrolysis refers to a biochemical reaction that occurs outside the cell before organic matter enters the microbial cell. Typically, sulfuric acid is used to prepare nanocellulose crystals. The initial research on the preparation of nanocellulose by acidification and hydrolysis has been widely used in the field of industrial production. The morphology of nanocellulose is shown in Figure 3.Figure 3
TEM images of nanocellulose prepared by sulfuric acid hydrolysis of different raw materials.As shown in Figure3, the fact that cellulose is a strong hydrophilic substance greatly limits its application range. Therefore, the hydrophobic modification of nanocellulose materials can expand the application scope and application environment of nanocellulose fibrils [14].


### 3.2. Density, Pore Volume, and Porosity of Metal Cellulose Nanocomposites

Because of the water insolubility of cellulose and the water absorption of the composite, the pore volumeVp of the composite can be calculated from the mass of the composite after water absorption. Therefore, Vp can be calculated according to (1)Vp=Mwet−MdrypMwet,p is the density of water [15].The air density inside the composite material is neglected, and its porosity is calculated according to(2)ρ%=1−ρbρs×100%.Among them,ρb is the bulk density of the composite material; ρs is the cellulose skeleton density.ZIF-8 is a zinc metal-organic framework. Compared with other ZIFs, ZIF-8 has a larger specific surface area and better chemical stability. By measuring the density, porosity, and pore volume of metal-organic framework/cellulose nanocomposites with different ZIF-8 loadings, this paper also explores the effect of ZIF-8 content on the microstructure of composites [16]. The results are shown in Table 2.Table 2
Effect of ZIF-8 content on the microstructure of composites.
SamplePore volume (cm3/g)Pore volume (cm3/g)Density (g/cm3)10 wt% ZIF-831.5196.10.03615 wt% ZIF-824.2696.00.04220 wt% ZIF-820.4395.70.05625 wt% ZIF-819.3294.60.05930 wt% ZIF-818.2294.20.065As shown in Table2, when the loading of ZIF-8 increased from 10 wt% to 30 wt%, the porosity and pore volume of the composites gradually decreased, and the density gradually increased. However, the porosity of the composite with 30wt% ZIF-8 loading still exceeds 94%, which still has ultralight characteristics [17]. The morphological structure of the metal-organic framework/cellulose nanocomposite is shown in Figure 4.Figure 4
Scanning electron microscope image of the composite.
(a)(b)As shown in Figure4, the scanning electron microscope image showed that the cellulose molecular chains in the composite were cross-linked by MBA to form an obvious interconnected three-dimensional porous structure [18]. While ZIF-8 attached to the cellulose channels in the composite showed different hierarchical porous structures, the macroporous three-dimensional network structure in the composite material is mainly composed of cellulose molecules, and the presence of ZIF-8 makes the composite material have a multilevel pore structure [19].Advanced protective clothing is made of nanofibers; its fabric is porous and has a membrane, which not only allows air to pass through and is breathable, but also blocks wind and filters fine particles and has a barrier to aerosols; it can prevent biological and chemical weapons and toxic substances. In addition, nanofibers can also be used for purification and filtration of chemical, pharmaceutical, and other products. Organometallic framework/cellulose nanocomposites can be utilized to adsorb heavy metal ions such as copper and cadmium in water. First, a heavy metal ion standard curve with various heavy metal ion concentrations was created, and three parallel samples were evaluated for each group of samples, with the average value obtained [20]. Then, according to the standard curve, the concentration of heavy metal ions at each moment can be known, and finally the adsorption characteristics of the composite material are found.Before adsorption, the standard curve formula of heavy metal ions is(3)b0=ax0+y.Among them,b0 is the absorbance before adsorption.The adsorption capacity of the composite material for heavy metal ions under different conditions is shown in(4)qt=c0−ctvw.Among them,c0 and ct/ are the concentrations of heavy metal ions before adsorption, namely, t = 0 and after the adsorption time t, respectively. The removal rate of heavy metal ions by the composite material is shown in (5)r=c0−ctc0.Among them,c0 and ctmg/L are the concentrations of heavy metal ions before adsorption, namely, t = 0 and after adsorption time t, respectively.Nanocellulose fibrils are usually prepared by mechanical methods. Since there is no hydrolysis reaction in the preparation process, the crystalline and noncrystalline regions in the cellulose chain are retained. Its aspect ratio is high, 3–5 times that of nanocellulose whiskers, and its toughness is much higher than that of nanocellulose whiskers. In the composite material, the elasticity, impact resistance, and bending performance are better [21]. The effect of adsorption time on the adsorption of heavy metal ions by composites is shown in Figure 5:Figure 5
Variation curve of adsorption performance of composites for different heavy metal ions with time at different initial concentrations: (a) variation of adsorption performance with time from 0 to 180 min and (b) variation of adsorption performance with time for 10–80 min.
(a)(b)As shown in Figure5, at the beginning of the adsorption phase, the adsorption speed accelerated, and as time went on, the adsorption speed gradually decreased until the adsorption dynamic equilibrium was reached. This may be because there are many available adsorption active sites on the composite at the beginning of adsorption, and, as the adsorption progresses, the available adsorption active sites gradually decrease before the adsorption active sites reach saturation. Dynamic equilibrium is reached, and the adsorption capacity no longer increases.The pseudo-second-order model is a kinetic model, which means that, in a certain concentration range, it proves that the adsorption rate is proportional to the square of the concentration or pressure of the adsorbate. The pseudo-second-order kinetic model refers to a linear relationship between the reaction rate and the concentrations of the two reactants. The variation of adsorption amount with adsorption time can be explained by the pseudo-second-order model. Its formulas are as formulas (6) and (7), respectively:(6)Inqe−qt=Inqe−K1t,(7)tqt=1k2qe2+tqe.Among them,qe represents the adsorption amount at adsorption equilibrium (mg/g).It can be seen that the adsorption kinetic constant of metal-organic framework/fiber nanocomposites for heavy metal ion adsorption increases with the increase of the initial concentration of heavy metal ions, indicating that the higher the concentration, the faster the adsorption rate.


### 3.3. Effect of Adsorbent Amount on Adsorption Performance and Adsorption Isotherm Formula

The adsorption isotherm fitted by the Langmuir model is an approximation to the adsorption process of the solute, and its basic assumption is that the adsorbate can only be adsorbed in a monolayer on the adsorbent. The adsorption isotherm is obtained by fully adsorbing heavy metal ions on the metal-organic framework/cellulose nanocomposite for a period of time to reach the adsorption equilibrium. The Langmuir adsorption isotherm formula is(8)Ceqe=Ceqm+1bqm,qm can be obtained by plotting the curve and the inverse of the slope of Ce, and b is obtained by plotting the curve and the Ce-intercept. The Freundlich formula is (9)Inqe=InKF+1nInCe.The adsorption isotherm model parameters of composite materials for different heavy metal ions are shown in Table3:Table 3
Adsorption isotherm model parameters of composites for different heavy metal ions.
TypeLangmuir isothermsFreundlich isothermsqm(mg/g)b(mg)r12r12 KF(mg-1)r22Cr(VI)40.730.01260.98331.1160.9623Cd2+47.200.03400.98419.4870.9732Cu2+256.280.1160.008480.440.9837As shown in Table3, the adsorption of heavy metal ions by the composites is an easy-to-perform chemical adsorption. The theoretical adsorption capacities of Cr(VI), Cd2+, and Cu2+ on the composites under the Langmuir model can reach 40.73 mg/g, 47.20 mg/g, and 256.28 mg/g, respectively. It can be seen that the composite material has good adsorption capacity as an adsorbent.


### 3.4. Differential Scanning Calorimetry (DSC)

The curve recorded by the differential scanning calorimeter is called DSC curve, which can measure various thermodynamic and kinetic parameters according to the rate at which the sample absorbs or releases heat. The thermal properties of the samples were analyzed with a DSC4000 differential scanning calorimeter. The samples with a mass of about 5 mg were placed in an aluminum crucible and sealed and placed in the instrument according to the principle of left sample and right reference. The protective gas was nitrogen, recording the secondary heating curve. The calculation formula of crystallinityAc is as (10)Ac=ΔHmΔHf×100WPLA.Tensile strength is the stress at which the specimen produces maximum uniform plastic deformation, denoted by the symbolσ, as in (11)σ=NS.The elongation at break refers to the ratio of the displacement generated by the sample to the original length when it breaks, which is represented by the symbolε, as shown in (12)ε=L1−L0L0×100%.Among them,L1 is the length between the clamps after tensile fracture of the sample, and L0 is the length (mm) between the clamps before stretching.The temperature program was set as described in formula (10) Differential Scanning Calorimetry (DSC). The calculation formula of crystallinity Ac is (13)Ac=ΔHm−ΔHccΔHf×100WPLA.After drying at 60°C for 48 h, the samples were weighed to a constant mass, and the cut samples were completely immersed in PBS buffer with pH 7.4 at room temperature. After 24 h, 48h, 72h, and 96h, respectively, take out and wipe off the residual water on the surface and weigh again immediately. The water absorption rate is(14)h1=M2−M1M1×100%.Among them,M1 is the mass after drying to constant weight, and M2 is the mass after water absorption.The most common way to study isothermal crystallization kinetics is to apply the Avrami formula, and use the Avrami model to obtain the functional relationship between the relative crystallinityAt at any temperature and the crystallization time t, as shown in (15)At=1−exp−Ktn.Among them,n is the Avrami index, and K is the crystallization rate constant. Taking the logarithm of both sides of formula (15) yields (16)lg−In1−At=lgK+nlgt.The morphology of the prepared cellulose nanofibers was changed after mechanical refinement, and the infrared spectrum analysis showed that there were hydrogen bonds between the cellulose nanofibers and polylactic acid molecules. X-ray diffraction indicated that the cellulose nanofibers had an effect on the crystal structure of the composites. Nanocellulose also has better physical and chemical properties, and the PLA polymer of this material has high strength and biodegradability. In addition, it has unparalleled advantages over conventional petroleum-based plastics.


### 3.5. The Performance and Feature Classification of Animation Character Modeling

Animated characters are basically made by animators, and even real characters, like the makeup of live-action film and TV actors, are artistically manipulated in lines and shapes during the deformation process. Likewise, there is more room for creative modeling in animation production; whether it is fiction or a second creation of a literary work, all animation character modeling is inseparable from the imagination of the animation designer. As people often say “there are thousands of readers, and there are thousands of Hamlet,” because of different imaginations, even the design of the same character is very different. Imagination and the artistic expression of the designer created the look of this character. It is said that character design is the basis of animation art and the most important part of the animation production process. The modeling performance of each animation character is different. Today’s society is an information society. In the hearts of animation lovers, animation stars from various countries have been remembered since ancient times, and the characteristics of each character are loved by the audience. When an animation creator makes it, he is also influenced by the styles of the various animation stars.


### 3.6. Classification of Animation Character Modeling

Animation, from its birth to its development, showcases many excellent looks, including the modeling of funny, cute, majestic, elegant, humorous, or hateful animated characters. Driven by the development and advancement of various animation techniques, a wide variety of styles and character forms have been produced. Animation character modeling can be divided into free-hand, real, anthropomorphic, cute, and other forms according to shapeand structure.(1)
Realistic type. The realistic type also has some shapes designed through artistic exaggeration and changes in its performance. For example, the exaggerated shapes of the four masters and apprentices in “Havoc in Heaven,” especially the shapes of characters such as Zhu Bajie and the geek in “The Man in the Clock Tower.” “Havoc in Heaven” is shown in Figure6.As shown in Figure6, these shapes are some distance from real-life character modeling and prototyping. According to the design and innovation of character modeling, animation character modeling is different from the actual character modeling based on realism and has the creativity and characteristics of expressing artistry.(2)
Anthropomorphic modeling. If the animals, plants, and other nonexistent objects in the comics become the protagonists of the animation, even if there are no characters in the movie, the producers will use these to express people’s feelings. Therefore, the characters and performances of the manga are anthropomorphic. According to the characteristics of animals, creatures, or other nonplants, the character modeling design of human form often gives people the image of psychology, personality, and comic characters, such as fanaticism, fusion, and exaggeration. So, their performances make people feel close, and this intimacy will give the audience a good experience.(3)
Cute type. The character modeling of animation characters is generally dominated by cute and sweet modeling. From the perspective of style, there are three main styles of animation characters, namely, aesthetic, realistic, and cartoon. The character design of animation is used more in cute comics. Such models are based on the artistic transformation of character modeling, and most of the naturally formed characters can be seen, which well expresses the characteristics of personality. The character modeling in Snow White is shown in Figure7.Figure 6
Animation character modeling in “Havoc in Heaven.”Figure 7
Animated character modeling in Snow White.
(a)(b)(c)As shown in Figure7, based on the seven dwarfs in “Snow White,” the proportions of the children’s bodies are used to completely exaggerate the dwarves, highlighting the cuteness and tenderness of the dwarves.


## 3.1. Nanocellulose and Preparation Method

Nanocellulose material is a new type of nanoscale biodegradable material with large specific surface area, high Young’s modulus, high adsorption performance, and high reactivity. It is a nanocellulose material with a high aspect ratio in the crystalline field [8]. Nanofiber refers to a wire-like material with a diameter of nanometer scale and a large length with a certain aspect ratio. In addition, the fibers that are modified by filling nanoparticles into ordinary fibers are also called nanofibers. Nanocellulose materials made of nanocellulose films and nanocellulose are widely used in chemical industry, materials, food, medicine, and other fields [9].The classification according to the preparation method and size of cellulose is shown in Table1.Table 1
Classification of nanocellulose.
namePreparationLength (nm)Diameter (nm)Cellulose nanocrystalsChemical method15020Cellulose nanofibersPhysical law100218Bacterial celluloseBiological law10026As shown in Table1, nanocellulose reaches nanoscale dimensions in at least one dimension, and its properties are quite different from those of pristine cellulose. Studies have shown that the proportion of crystallinity domains can be increased through a series of mechanical, chemical, and biological methods that destroy the structure of natural cellulose amorphous domains [10].


### 3.1.1. Preparation of Cellulose Nanofibers by Mechanical Method

Mechanical methods include various physical and mechanical treatment methods such as strong shearing, pulverization, high-pressure equalization, microfluidics, and high-density ultrasound [11]. High pressure homogenizer is also called “high pressure fluid nano homogenizer.” It can make the material in the state of suspension flow through the cavity with special internal structure at high speed under the action of ultrahigh pressure (up to 60000psi), so that the material undergoes a series of changes in physical, chemical, and structural properties, etc., and finally achieves homogeneity effect. The preparation of microspheres of cellulose by high pressure homogenization is mainly carried out through the coaxial homogenization valve in the homogenizer. The schematic diagram of the structure of a typical high-pressure homogenizer is shown in Figure 2.Figure 2
Schematic diagram of the structure of a typical high-pressure homogenizer.As shown in Figure2, if the regulating valve is opened and closed continuously, a cavitation effect will occur, and the raw cellulose collides at high speed through cavitation, so that the cellulose fibers are gradually separated, and microfibrillated cellulose is gradually obtained [12].


### 3.1.2. Preparation of Nanocellulose Crystals by Acid Hydrolysis

Nanocellulose crystals are prepared by acid hydrolysis, and strong acid is used to destroy the amorphous regions of the cellulose structure, so that they maintain neatly arranged high-density crystalline regions [13]. Acidified hydrolysis generally refers to hydrolytic acidification. The hydrolysis treatment method is a method between the aerobic and the anaerobic treatment methods, and the combination of other processes can reduce the treatment cost and improve the treatment efficiency. Hydrolysis refers to a biochemical reaction that occurs outside the cell before organic matter enters the microbial cell. Typically, sulfuric acid is used to prepare nanocellulose crystals. The initial research on the preparation of nanocellulose by acidification and hydrolysis has been widely used in the field of industrial production. The morphology of nanocellulose is shown in Figure 3.Figure 3
TEM images of nanocellulose prepared by sulfuric acid hydrolysis of different raw materials.As shown in Figure3, the fact that cellulose is a strong hydrophilic substance greatly limits its application range. Therefore, the hydrophobic modification of nanocellulose materials can expand the application scope and application environment of nanocellulose fibrils [14].


## 3.1.1. Preparation of Cellulose Nanofibers by Mechanical Method

Mechanical methods include various physical and mechanical treatment methods such as strong shearing, pulverization, high-pressure equalization, microfluidics, and high-density ultrasound [11]. High pressure homogenizer is also called “high pressure fluid nano homogenizer.” It can make the material in the state of suspension flow through the cavity with special internal structure at high speed under the action of ultrahigh pressure (up to 60000psi), so that the material undergoes a series of changes in physical, chemical, and structural properties, etc., and finally achieves homogeneity effect. The preparation of microspheres of cellulose by high pressure homogenization is mainly carried out through the coaxial homogenization valve in the homogenizer. The schematic diagram of the structure of a typical high-pressure homogenizer is shown in Figure 2.Figure 2
Schematic diagram of the structure of a typical high-pressure homogenizer.As shown in Figure2, if the regulating valve is opened and closed continuously, a cavitation effect will occur, and the raw cellulose collides at high speed through cavitation, so that the cellulose fibers are gradually separated, and microfibrillated cellulose is gradually obtained [12].


## 3.1.2. Preparation of Nanocellulose Crystals by Acid Hydrolysis

Nanocellulose crystals are prepared by acid hydrolysis, and strong acid is used to destroy the amorphous regions of the cellulose structure, so that they maintain neatly arranged high-density crystalline regions [13]. Acidified hydrolysis generally refers to hydrolytic acidification. The hydrolysis treatment method is a method between the aerobic and the anaerobic treatment methods, and the combination of other processes can reduce the treatment cost and improve the treatment efficiency. Hydrolysis refers to a biochemical reaction that occurs outside the cell before organic matter enters the microbial cell. Typically, sulfuric acid is used to prepare nanocellulose crystals. The initial research on the preparation of nanocellulose by acidification and hydrolysis has been widely used in the field of industrial production. The morphology of nanocellulose is shown in Figure 3.Figure 3
TEM images of nanocellulose prepared by sulfuric acid hydrolysis of different raw materials.As shown in Figure3, the fact that cellulose is a strong hydrophilic substance greatly limits its application range. Therefore, the hydrophobic modification of nanocellulose materials can expand the application scope and application environment of nanocellulose fibrils [14].


## 3.2. Density, Pore Volume, and Porosity of Metal Cellulose Nanocomposites

Because of the water insolubility of cellulose and the water absorption of the composite, the pore volumeVp of the composite can be calculated from the mass of the composite after water absorption. Therefore, Vp can be calculated according to (1)Vp=Mwet−MdrypMwet,p is the density of water [15].The air density inside the composite material is neglected, and its porosity is calculated according to(2)ρ%=1−ρbρs×100%.Among them,ρb is the bulk density of the composite material; ρs is the cellulose skeleton density.ZIF-8 is a zinc metal-organic framework. Compared with other ZIFs, ZIF-8 has a larger specific surface area and better chemical stability. By measuring the density, porosity, and pore volume of metal-organic framework/cellulose nanocomposites with different ZIF-8 loadings, this paper also explores the effect of ZIF-8 content on the microstructure of composites [16]. The results are shown in Table 2.Table 2
Effect of ZIF-8 content on the microstructure of composites.
SamplePore volume (cm3/g)Pore volume (cm3/g)Density (g/cm3)10 wt% ZIF-831.5196.10.03615 wt% ZIF-824.2696.00.04220 wt% ZIF-820.4395.70.05625 wt% ZIF-819.3294.60.05930 wt% ZIF-818.2294.20.065As shown in Table2, when the loading of ZIF-8 increased from 10 wt% to 30 wt%, the porosity and pore volume of the composites gradually decreased, and the density gradually increased. However, the porosity of the composite with 30wt% ZIF-8 loading still exceeds 94%, which still has ultralight characteristics [17]. The morphological structure of the metal-organic framework/cellulose nanocomposite is shown in Figure 4.Figure 4
Scanning electron microscope image of the composite.
(a)(b)As shown in Figure4, the scanning electron microscope image showed that the cellulose molecular chains in the composite were cross-linked by MBA to form an obvious interconnected three-dimensional porous structure [18]. While ZIF-8 attached to the cellulose channels in the composite showed different hierarchical porous structures, the macroporous three-dimensional network structure in the composite material is mainly composed of cellulose molecules, and the presence of ZIF-8 makes the composite material have a multilevel pore structure [19].Advanced protective clothing is made of nanofibers; its fabric is porous and has a membrane, which not only allows air to pass through and is breathable, but also blocks wind and filters fine particles and has a barrier to aerosols; it can prevent biological and chemical weapons and toxic substances. In addition, nanofibers can also be used for purification and filtration of chemical, pharmaceutical, and other products. Organometallic framework/cellulose nanocomposites can be utilized to adsorb heavy metal ions such as copper and cadmium in water. First, a heavy metal ion standard curve with various heavy metal ion concentrations was created, and three parallel samples were evaluated for each group of samples, with the average value obtained [20]. Then, according to the standard curve, the concentration of heavy metal ions at each moment can be known, and finally the adsorption characteristics of the composite material are found.Before adsorption, the standard curve formula of heavy metal ions is(3)b0=ax0+y.Among them,b0 is the absorbance before adsorption.The adsorption capacity of the composite material for heavy metal ions under different conditions is shown in(4)qt=c0−ctvw.Among them,c0 and ct/ are the concentrations of heavy metal ions before adsorption, namely, t = 0 and after the adsorption time t, respectively. The removal rate of heavy metal ions by the composite material is shown in (5)r=c0−ctc0.Among them,c0 and ctmg/L are the concentrations of heavy metal ions before adsorption, namely, t = 0 and after adsorption time t, respectively.Nanocellulose fibrils are usually prepared by mechanical methods. Since there is no hydrolysis reaction in the preparation process, the crystalline and noncrystalline regions in the cellulose chain are retained. Its aspect ratio is high, 3–5 times that of nanocellulose whiskers, and its toughness is much higher than that of nanocellulose whiskers. In the composite material, the elasticity, impact resistance, and bending performance are better [21]. The effect of adsorption time on the adsorption of heavy metal ions by composites is shown in Figure 5:Figure 5
Variation curve of adsorption performance of composites for different heavy metal ions with time at different initial concentrations: (a) variation of adsorption performance with time from 0 to 180 min and (b) variation of adsorption performance with time for 10–80 min.
(a)(b)As shown in Figure5, at the beginning of the adsorption phase, the adsorption speed accelerated, and as time went on, the adsorption speed gradually decreased until the adsorption dynamic equilibrium was reached. This may be because there are many available adsorption active sites on the composite at the beginning of adsorption, and, as the adsorption progresses, the available adsorption active sites gradually decrease before the adsorption active sites reach saturation. Dynamic equilibrium is reached, and the adsorption capacity no longer increases.The pseudo-second-order model is a kinetic model, which means that, in a certain concentration range, it proves that the adsorption rate is proportional to the square of the concentration or pressure of the adsorbate. The pseudo-second-order kinetic model refers to a linear relationship between the reaction rate and the concentrations of the two reactants. The variation of adsorption amount with adsorption time can be explained by the pseudo-second-order model. Its formulas are as formulas (6) and (7), respectively:(6)Inqe−qt=Inqe−K1t,(7)tqt=1k2qe2+tqe.Among them,qe represents the adsorption amount at adsorption equilibrium (mg/g).It can be seen that the adsorption kinetic constant of metal-organic framework/fiber nanocomposites for heavy metal ion adsorption increases with the increase of the initial concentration of heavy metal ions, indicating that the higher the concentration, the faster the adsorption rate.


## 3.3. Effect of Adsorbent Amount on Adsorption Performance and Adsorption Isotherm Formula

The adsorption isotherm fitted by the Langmuir model is an approximation to the adsorption process of the solute, and its basic assumption is that the adsorbate can only be adsorbed in a monolayer on the adsorbent. The adsorption isotherm is obtained by fully adsorbing heavy metal ions on the metal-organic framework/cellulose nanocomposite for a period of time to reach the adsorption equilibrium. The Langmuir adsorption isotherm formula is(8)Ceqe=Ceqm+1bqm,qm can be obtained by plotting the curve and the inverse of the slope of Ce, and b is obtained by plotting the curve and the Ce-intercept. The Freundlich formula is (9)Inqe=InKF+1nInCe.The adsorption isotherm model parameters of composite materials for different heavy metal ions are shown in Table3:Table 3
Adsorption isotherm model parameters of composites for different heavy metal ions.
TypeLangmuir isothermsFreundlich isothermsqm(mg/g)b(mg)r12r12 KF(mg-1)r22Cr(VI)40.730.01260.98331.1160.9623Cd2+47.200.03400.98419.4870.9732Cu2+256.280.1160.008480.440.9837As shown in Table3, the adsorption of heavy metal ions by the composites is an easy-to-perform chemical adsorption. The theoretical adsorption capacities of Cr(VI), Cd2+, and Cu2+ on the composites under the Langmuir model can reach 40.73 mg/g, 47.20 mg/g, and 256.28 mg/g, respectively. It can be seen that the composite material has good adsorption capacity as an adsorbent.


## 3.4. Differential Scanning Calorimetry (DSC)

The curve recorded by the differential scanning calorimeter is called DSC curve, which can measure various thermodynamic and kinetic parameters according to the rate at which the sample absorbs or releases heat. The thermal properties of the samples were analyzed with a DSC4000 differential scanning calorimeter. The samples with a mass of about 5 mg were placed in an aluminum crucible and sealed and placed in the instrument according to the principle of left sample and right reference. The protective gas was nitrogen, recording the secondary heating curve. The calculation formula of crystallinityAc is as (10)Ac=ΔHmΔHf×100WPLA.Tensile strength is the stress at which the specimen produces maximum uniform plastic deformation, denoted by the symbolσ, as in (11)σ=NS.The elongation at break refers to the ratio of the displacement generated by the sample to the original length when it breaks, which is represented by the symbolε, as shown in (12)ε=L1−L0L0×100%.Among them,L1 is the length between the clamps after tensile fracture of the sample, and L0 is the length (mm) between the clamps before stretching.The temperature program was set as described in formula (10) Differential Scanning Calorimetry (DSC). The calculation formula of crystallinity Ac is (13)Ac=ΔHm−ΔHccΔHf×100WPLA.After drying at 60°C for 48 h, the samples were weighed to a constant mass, and the cut samples were completely immersed in PBS buffer with pH 7.4 at room temperature. After 24 h, 48h, 72h, and 96h, respectively, take out and wipe off the residual water on the surface and weigh again immediately. The water absorption rate is(14)h1=M2−M1M1×100%.Among them,M1 is the mass after drying to constant weight, and M2 is the mass after water absorption.The most common way to study isothermal crystallization kinetics is to apply the Avrami formula, and use the Avrami model to obtain the functional relationship between the relative crystallinityAt at any temperature and the crystallization time t, as shown in (15)At=1−exp−Ktn.Among them,n is the Avrami index, and K is the crystallization rate constant. Taking the logarithm of both sides of formula (15) yields (16)lg−In1−At=lgK+nlgt.The morphology of the prepared cellulose nanofibers was changed after mechanical refinement, and the infrared spectrum analysis showed that there were hydrogen bonds between the cellulose nanofibers and polylactic acid molecules. X-ray diffraction indicated that the cellulose nanofibers had an effect on the crystal structure of the composites. Nanocellulose also has better physical and chemical properties, and the PLA polymer of this material has high strength and biodegradability. In addition, it has unparalleled advantages over conventional petroleum-based plastics.


## 3.5. The Performance and Feature Classification of Animation Character Modeling

Animated characters are basically made by animators, and even real characters, like the makeup of live-action film and TV actors, are artistically manipulated in lines and shapes during the deformation process. Likewise, there is more room for creative modeling in animation production; whether it is fiction or a second creation of a literary work, all animation character modeling is inseparable from the imagination of the animation designer. As people often say “there are thousands of readers, and there are thousands of Hamlet,” because of different imaginations, even the design of the same character is very different. Imagination and the artistic expression of the designer created the look of this character. It is said that character design is the basis of animation art and the most important part of the animation production process. The modeling performance of each animation character is different. Today’s society is an information society. In the hearts of animation lovers, animation stars from various countries have been remembered since ancient times, and the characteristics of each character are loved by the audience. When an animation creator makes it, he is also influenced by the styles of the various animation stars.


## 3.6. Classification of Animation Character Modeling

Animation, from its birth to its development, showcases many excellent looks, including the modeling of funny, cute, majestic, elegant, humorous, or hateful animated characters. Driven by the development and advancement of various animation techniques, a wide variety of styles and character forms have been produced. Animation character modeling can be divided into free-hand, real, anthropomorphic, cute, and other forms according to shapeand structure.(1)
Realistic type. The realistic type also has some shapes designed through artistic exaggeration and changes in its performance. For example, the exaggerated shapes of the four masters and apprentices in “Havoc in Heaven,” especially the shapes of characters such as Zhu Bajie and the geek in “The Man in the Clock Tower.” “Havoc in Heaven” is shown in Figure6.As shown in Figure6, these shapes are some distance from real-life character modeling and prototyping. According to the design and innovation of character modeling, animation character modeling is different from the actual character modeling based on realism and has the creativity and characteristics of expressing artistry.(2)
Anthropomorphic modeling. If the animals, plants, and other nonexistent objects in the comics become the protagonists of the animation, even if there are no characters in the movie, the producers will use these to express people’s feelings. Therefore, the characters and performances of the manga are anthropomorphic. According to the characteristics of animals, creatures, or other nonplants, the character modeling design of human form often gives people the image of psychology, personality, and comic characters, such as fanaticism, fusion, and exaggeration. So, their performances make people feel close, and this intimacy will give the audience a good experience.(3)
Cute type. The character modeling of animation characters is generally dominated by cute and sweet modeling. From the perspective of style, there are three main styles of animation characters, namely, aesthetic, realistic, and cartoon. The character design of animation is used more in cute comics. Such models are based on the artistic transformation of character modeling, and most of the naturally formed characters can be seen, which well expresses the characteristics of personality. The character modeling in Snow White is shown in Figure7.Figure 6
Animation character modeling in “Havoc in Heaven.”Figure 7
Animated character modeling in Snow White.
(a)(b)(c)As shown in Figure7, based on the seven dwarfs in “Snow White,” the proportions of the children’s bodies are used to completely exaggerate the dwarves, highlighting the cuteness and tenderness of the dwarves.


## 4. Fretting Fatigue Test of Elastic-Plastic Fiber Metal Laminates

### 4.1. Experiment Preparation

In order to better and more intuitively understand the impact of fretting fatigue on animation character modeling components, people simulate the stress of animation character modeling components through fatigue tests. The fretting fatigue test is fully considered and designed, and the fretting fatigue data of the components are obtained, so that the fatigue characteristics of the components can be analyzed and evaluated correctly. The corresponding material parameters are obtained, and the fretting damage prediction model is established to correctly judge the crack initiation position, damage mechanism, and life.In the process of fatigue experiment, if the loading frequency is too high, the fatigue testing machine will resonate, and the dynamic response cannot be made in time. If the loading frequency is too low, the experiment period will be too long. Therefore, according to the operation specification of the fatigue testing machine, the loading frequency of the experiment is selected as 10 Hz, and the load waveform adopts the form of sine wave. According to the three methods of calculating the strain energy density before, we also use the above three methods to predict the life of the formula to study the fretting fatigue life of the sample member.The formula for the SWT rule to predict life is(17)SWT=σmaxΔεa=σf′2E2Nfb+σf′εf′2Nfb+c.Under three sets of cyclic loads, the calculated SWT values of strain energy density are shown in Figure8.Figure 8
Strain Energy Density SWT Values: (a) distribution of SWT along the contact path and (b) SWT distributed along the angle.
(a)(b)As shown in Figure8, according to the conclusion drawn from the previous calculation results, the outer end near the contact area is the first to break. Therefore, it is the most accurate to select the SWT value near the outer end of the contact area as the life prediction and fit its peak value to the test data.


### 4.2. Experimental Results

The elastic fibers are located in the reticular layer of the dermis, and their arrangement is parallel or oblique to the collagen fibers. There are more elastic fibers in the lower part of the reticular layer, which can increase the skin toughness and make the movement parts move freely. After obtaining the above SWT value, people fit the obtained experimental data with formula (17), and the obtained fitted data curve is shown in Figure 9.Figure 9
Curve fitting plot.
(a)(b)As shown in Figure9, there are many methods for forming the elastic-plastic fiber-metal laminate. This test adopts the hand-made method, which is convenient and flexible, easy to master and operate, and can be aimed at the cracking of the fiber-metal laminate due to the uneven application of epoxy glue during the production process.The comparison between the experimental results and the predicted results of the SWT method is shown in Table4.Table 4
Comparison of SWT method test results and predicted results.
Number of experimentsCyclic load maximum value (MPa)Measured cycle timesPredict the number of cycles11202052002120165162312017817941201701755120183180As shown in Table4, the experimental results are in good agreement with the predicted results, in order to observe the comparison results between the experimental and the predicted values of lifespan and the effect of fitting more clearly. The results predicted by the above methods are marked in Table 4; the predicted results are all within the allowable error range, and the predicted life is consistent with the measured life. It shows that metal cellulose nanomaterials can prolong the life of modeling in decorative animation character modeling.


## 4.1. Experiment Preparation

In order to better and more intuitively understand the impact of fretting fatigue on animation character modeling components, people simulate the stress of animation character modeling components through fatigue tests. The fretting fatigue test is fully considered and designed, and the fretting fatigue data of the components are obtained, so that the fatigue characteristics of the components can be analyzed and evaluated correctly. The corresponding material parameters are obtained, and the fretting damage prediction model is established to correctly judge the crack initiation position, damage mechanism, and life.In the process of fatigue experiment, if the loading frequency is too high, the fatigue testing machine will resonate, and the dynamic response cannot be made in time. If the loading frequency is too low, the experiment period will be too long. Therefore, according to the operation specification of the fatigue testing machine, the loading frequency of the experiment is selected as 10 Hz, and the load waveform adopts the form of sine wave. According to the three methods of calculating the strain energy density before, we also use the above three methods to predict the life of the formula to study the fretting fatigue life of the sample member.The formula for the SWT rule to predict life is(17)SWT=σmaxΔεa=σf′2E2Nfb+σf′εf′2Nfb+c.Under three sets of cyclic loads, the calculated SWT values of strain energy density are shown in Figure8.Figure 8
Strain Energy Density SWT Values: (a) distribution of SWT along the contact path and (b) SWT distributed along the angle.
(a)(b)As shown in Figure8, according to the conclusion drawn from the previous calculation results, the outer end near the contact area is the first to break. Therefore, it is the most accurate to select the SWT value near the outer end of the contact area as the life prediction and fit its peak value to the test data.


## 4.2. Experimental Results

The elastic fibers are located in the reticular layer of the dermis, and their arrangement is parallel or oblique to the collagen fibers. There are more elastic fibers in the lower part of the reticular layer, which can increase the skin toughness and make the movement parts move freely. After obtaining the above SWT value, people fit the obtained experimental data with formula (17), and the obtained fitted data curve is shown in Figure 9.Figure 9
Curve fitting plot.
(a)(b)As shown in Figure9, there are many methods for forming the elastic-plastic fiber-metal laminate. This test adopts the hand-made method, which is convenient and flexible, easy to master and operate, and can be aimed at the cracking of the fiber-metal laminate due to the uneven application of epoxy glue during the production process.The comparison between the experimental results and the predicted results of the SWT method is shown in Table4.Table 4
Comparison of SWT method test results and predicted results.
Number of experimentsCyclic load maximum value (MPa)Measured cycle timesPredict the number of cycles11202052002120165162312017817941201701755120183180As shown in Table4, the experimental results are in good agreement with the predicted results, in order to observe the comparison results between the experimental and the predicted values of lifespan and the effect of fitting more clearly. The results predicted by the above methods are marked in Table 4; the predicted results are all within the allowable error range, and the predicted life is consistent with the measured life. It shows that metal cellulose nanomaterials can prolong the life of modeling in decorative animation character modeling.


## 5. Conclusions

Animation characters are the basis of animation, and the success of character shaping is related to the success of animation. The roles in films can usually be divided into protagonists, supporting roles, and extras. Undoubtedly, the weight of the protagonist plays a pivotal role in animation. With the improvement of people’s living standards, people’s pursuit of spiritual culture has become higher and higher. Cartoons are not only loved by children, but also welcomed by adults. Allegorical animations can not only increase interest, but also develop sentiment. Therefore, the decoration of the animation character modeling in the cartoon becomes particularly important. Because of its good properties, metal fiber nanomaterials can play a role in the decoration of animation character modeling. This article revolves around metal cellulose nanocomposites and animation character modeling. In this paper, the preparation and properties of metal cellulose nanocomposites are analyzed in detail, and the characteristics of animation character modeling are also described. In the experimental part, the lifespan of animation character modeling after applying metal cellulose nanocomposites was also tested. Finally, it was found that metal cellulose nanocomposites can not only enhance the visual aesthetics of animation character modeling, but also prolong the life of animation character modeling.



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*Source: 8906830-2022-09-14.xml*