KR20210143996A - Biodegradable materials based on defatted Chlorella biomass and its preparing method - Google Patents

Abstract

The present invention relates to a biodegradable material based on chitosan and defatted chlorella biomass (DCB) and a method for preparing the same. Particularly, the present invention relates to use of DCB as an additive of a chitosan-based formulation for the purpose of reducing the cost required for materials and for improving the performance of the resultant composite material at the same time. According to the present invention, the biodegradable material can be applied widely to the field of bioplastics, including biodegradable and edible food packaging films, which have improved properties, such as heat stability, tensile strength, water steam permeability, water content and expandability, light transmission and opacity. In addition, polyurethane/DCB composite materials having improved properties, such as tensile strength, elongation at break, antioxidation degree and water absorptivity, can be produced and applied widely not only to the existing application field of polyurethane but also to the field of medical and food packaging films requiring antioxidative property.

Description

Biodegradable materials based on defatted Chlorella biomass and its preparing method

The present invention relates to a delipidated chlorella biomass-based biodegradable material and a method for manufacturing the same.

o-Martins, M., & Hickmann Fl

res, S. (2018). Active food packaging prepared with chitosan and olive pomace. Food Hydrocolloids, 74, 139-150).Recently, a practical solution has been studied for the development of biodegradable materials from renewable natural resources to mitigate the consumption of fossil fuels while reducing the negative environmental impact caused by the waste treatment of non-degradable plastic-based materials. Especially among various polysaccharides, chitosan obtained from deacetylation of chitin is of particular interest as a film-forming material due to its excellent film-forming ability, biodegradability, biocompatibility and low toxicity. Nevertheless, chitosan-based films are very hydrophilic, making them brittle and poor moisture barrier, which may limit their use in food packaging applications where moisture transfer control is required. In this regard, lipids including fatty acids and waxes were combined with chitosan to provide resistance to water movement. However, incorporation of lipids into chitosan-based films could weaken the three-dimensional network and negatively affect its mechanical properties. Thus, the concept of producing blends or multilayer films from selected biopolymers is emerging as a promising strategy to create new sustainable packaging materials with improved properties compared to films made from one component. In this context, Lan et al. reported a decrease in mechanical properties and hydrophilic properties of composite films in which chitosan, carboxymethylcellulose and sodium alginate were mixed in a ratio of 3: 1: 3 (Lan, W., He, L., & Liu, Y. (2018). Preparation and properties of sodium carboxymethyl cellulose/sodium alginate/chitosan composite film. Coatings, 8(8), 291). However, the practical use of composite or multi-layered hydrocolloid-based films is somewhat limited due to expensive biopolymers. Recently, development of new biomaterials from agricultural by-products and wastes is emerging as a major task through the development of eco-friendly technologies. In this context, Crizel et al. reported that the incorporation of olive residue powder into the chitosan matrix significantly improved the tensile strength of the film and increased its antioxidant capacity (de Moraes Crizel, T., de Oliveira Rios, A., D. Alves). , V., Bandarra, N., Mold

o-Martins, M., & Hickmann Fl

res, S. (2018). Active food packaging prepared with chitosan and olive pomace. Food Hydrocolloids, 74, 139-150).

Chlorella (Chlorophyta, Trebouxiophyceae) is one of the most extensively studied microalgae, with over 70 companies carrying out commercial-scale cultivation worldwide, with annual production of chlorella biomass estimated at over 2,000 tonnes. Chlorella biomass has been used for a variety of applications, mainly as a dietary supplement, as a feedstock for ethanol production, but only a few studies have reported its use in the development of bioplastics and thermoplastic mixtures (Zeller, MA, Hunt, R., Jones, A., & Sharma, S. (2013). Bioplastics and their thermoplastic blends from Spirulina and Chlorella microalgae. Journal of Applied Polymer Science, 130(5), 3263-3275). In addition, most have focused on using whole algal biomass rather than using delipidated residual algal biomass as an additive to conventional composites in the food packaging field (Otsuki, J., Zhang, F., Kabeya, H). ., & Hirotsu, T. (2004). Synthesis and Tensile Properties of a Novel Composite of Chlorella and Polyethylene. Journal of Applied Polymer Science, 92(2), 812-816). However, in the process of algal biodiesel production, large amounts of delipidated algal biomass rich in carbohydrates and proteins are produced (Yun, J.-H., Cho, D.-H., Lee, B., Lee, YJ, Choi, D.-Y., Kim, H.-S., & Chang, YK (2020).Utilization of the acid hydrolysate of defatted Chlorella biomass as a sole fermentation substrate for the production of biosurfactant from Bacillus subtilis C9. Algal Research, 47 , 101868), which can serve as feedstocks for bioplastics production.

Polyurethane (PU) is a polymer material that is generally synthesized by reacting an isocyanate containing two or more NCO groups with a polyol consisting of two or more hydroxyl groups. PU has good flexibility and good durability, but its low rigidity and weak strength may limit its application in many industrial fields. In order to improve the mechanical properties of PU and promote sustainability, low cost, and biodegradation, many researchers have been interested in the integration of PU with natural biofillers. (HD Rozman, YS Yeo, GS Tay, A. Abubakar, The mechanical and physical properties of polyurethane composites based on rice husk and polyethylene glycol, Polym. Test. 22 (2003) 617-623) is polyethylene glycol (PEG) was used as a polyol and diphenyl methane diisocyanate as a coupling agent to develop a PU/rice hull composite film, and to increase the tensile strength of the resulting composite. However, when peanut shells and pine bark were added as biofillers, the compressive strength of PU-based films was drastically reduced (Q. Zhang, X. Lin, W. Chen, H. Zhang, D. Han, Modification of rigid polyurethane foams). with the addition of nano-SiO2 or lignocellulosic biomass, Polymers 12 (2020) 107).

Therefore, in the present invention, defatted Chlorella biomass (DCB) was used as an additive to the polymer resin for the purpose of reducing the material cost and improving the performance of the composite material produced at the same time. To this end, the effect of heat treatment and DCB content on the physical and functional properties of the prepared chitosan/DCB (Cs/DCB) composite material was investigated. In addition, the present invention was completed by synthesizing a PU/DCB composite material by adding DCB to PEG-based PU and examining the physical and functional properties.

Republic of Korea Patent Registration No. 10-0466480 Republic of Korea Patent Publication No. 10-2019-0136975

Lan, W., He, L., & Liu, Y. (2018). Preparation and properties of sodium carboxymethyl cellulose/sodium alginate/chitosan composite film. Coatings, 8(8), 291 Otsuki, J., Zhang, F., Kabeya, H., & Hirotsu, T. (2004). Synthesis and Tensile Properties of a Novel Composite of Chlorella and Polyethylene. Journal of Applied Polymer Science, 92(2), 812-816 H.D. Rozman, Y.S. Yeo, G.S. Tay, A. Abubakar, The mechanical and physical properties of polyurethane composites based on rice husk and polyethylene glycol, Polym. Test. 22 (2003) 617-623

Therefore, an object of the present invention is a biodegradable, edible food packaging film with improved physical properties such as thermal stability, tensile strength, water vapor permeability, moisture content and expansion, light transmittance and opacity, which can be widely applied in the field of bioplastics. To provide a biodegradable material based on lipid chlorella biomass and a method for manufacturing the same. Another object of the present invention is to provide a delipidated chlorella biomass composite material with improved physical properties such as tensile strength, elongation at break, antioxidant, and water absorption, and a method for manufacturing the same.

Various problems to be solved in the present invention in the above are not limited thereto, but can be clearly understood by those of ordinary skill in the art to which the present invention pertains through the examples and claims to be described later. will be.

In order to achieve the above object, the present invention provides a method for economically manufacturing biodegradable bioplastics such as films by adding delipidated microalgal biomass to chitosan as a filler and improved physical properties thereof, in an amount selected relative to the mass of chitosan of DCB (5, 10, 15, 20, 25, 30 and 35 wt%) was dispersed in 1% acetic acid and then sonicated at room temperature for 30 min. After complete dispersion, 2% (w/v) chitosan was added to each DCB dispersion, and the resulting mixture was stirred continuously at room temperature for 24 hours. Glycerol as a plasticizer was then added to the film forming solution at a constant concentration of 20 wt % of chitosan. Each film-forming solution was poured into a 90 mm inner diameter Petri dish and dried at 40° C. for 24 hours to form a film with an average thickness of 100±7 μm. Then, the resulting film was heat-treated at 100 °C for 2 hours. The treated film is then prepared by conditioning in a chamber at 25° C. and 50% relative humidity for 48 hours.

According to the present invention as described above, by adding delipidated chlorella microalgal biomass, which is biodiesel production waste, to chitosan as a filler, thermal stability is improved, tensile strength is increased from 19.6 to 67.4 MPa, water vapor permeability, water content and reducing swelling and reducing light transmittance and opacity to inhibit food photooxidation. In addition, the resulting Cs/DCB complex can be biodegraded faster than 50% after being buried in soil for 60 days.

Therefore, by manufacturing a composite material using DCB with improved physical properties such as thermal stability, tensile strength, water vapor permeability, water content and expansion, light transmittance and opacity, elongation at break, antioxidant, and water absorption, construction, automobile, coating, sealant, It can be widely applied not only to the existing polyurethane application fields such as adhesives, foams, and composites, but also to medical and food packaging films that require antioxidant properties.

The effects according to the present invention in the above are not limited to the above, and other effects of the present invention can be clearly identified by those of ordinary skill in the art through the examples and claims to be described later. can be understood

1 shows a biodegradable film manufacturing process based on chitosan and delipidated chlorella biomass of the present invention.
Figure 2 shows the TGA and DTG curves of the chitosan and delipidated chlorella biomass-based composite film of the present invention, DCB, and chitosan (control).
Figure 3 shows the tensile strength versus deformation, tensile strength and elongation at break of the chitosan and delipidated chlorella biomass-based composite film of the present invention.
Figure 4 shows the water vapor permeability, water content and swelling degree of the chitosan and delipidated chlorella biomass-based composite film of the present invention.
5 shows the light transmittance and opacity according to the wavelength of the chitosan and delipidated chlorella biomass-based composite film of the present invention.
Figure 6 shows the images before and after contact with the soil of the chitosan and delipidated chlorella biomass-based composite film of the present invention.
7 shows the manufacturing process of the PEG-based polyurethane and the delipidated Chlorella biomass composite of the present invention.
Figure 8 shows the tensile strength of the PEG-based polyurethane and the delipidated chlorella biomass composite of the present invention.
9 shows the elongation at break of the PEG-based polyurethane and the delipidated chlorella biomass composite of the present invention.
10 shows the DPPH radical scavenging activity of the PEG-based polyurethane and the delipidated Chlorella biomass composite of the present invention.
11 shows the water absorption percentage of the PEG-based polyurethane and the delipidated Chlorella biomass composite of the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a delipidated chlorella biomass-based biodegradable material and a method for manufacturing the same.

According to the present invention, there is provided a biodegradable complex comprising a polymer resin and delipidated microalgal biomass.

Chlorella is a generic term for microalgae in the genus Chlorella and the green alga Chlorella, and it is one of the most extensively studied microalgae for the use of chlorella biomass by more than 70 companies that carry out commercial-scale cultivation worldwide. Annual production of chlorella biomass is estimated to be over 2,000 tonnes. Chlorella biomass is mainly used as a dietary supplement and as a feedstock for the production of ethanol. In the present invention, it was used to produce bioplastics and thermoplastic composites. According to the present invention, it is described as using chlorella, but Chlorella or Spirulina that can be used in biomass as microalgae can be used.

According to the present invention, defatted Chlorella biomass (DCB) was used as an additive to the polymer resin for the purpose of reducing the material cost and improving the performance of the composite material produced at the same time. To this end, chitosan/DCB (Cs/DCB) and PEG-based polyurethane/DCB (PU-PEG/DCB) composite materials prepared using delipidated chlorella biomass as an additive of chitosan-based formulations and PEG-based polyurethanes. and the effect of heat treatment and DCB content on functional properties.

In the present invention, the polymer resin substrate is polyimide (PI), polyimideamide (polyimideamide), polyetherimide (PEI), polyethyleneterephtalate (PET), polyethylenenaphthalate (PEN), poly Etheretherketone (polyetheretherketone, PEEK), cyclic olefin polymer (COP), polyacrylate (PAC), polymethylmethacrylate (PMMA), and triacetylcellulose (TAC) One or more synthetic polymers selected from the group consisting of , polyurethane (PU) may be used.

In addition, at least one natural polymer selected from the group consisting of hyaluronic acid, chitosan, cellulose, chondroitin sulfate, heparin, alginic acid, gelatin, collagen, dextran, and dermatan sulfate may be used.

In the present invention, preferably, a (meth)acrylate-based or (meth)acrylamide-based or polyurethane-based agent or chitosan, cellulose, alginic acid or dextran may be used as the hydrophilic polymer, and more preferably, polyurethane or chitosan may be used. Available.

In the present invention, one or more plasticizers selected from glycerol, polyethylene glycol, triethyl citrate, and sorbitol may be used as the plasticizer. More preferably, glycerol or polyethylene glycol may be used.

In the present invention, the amount of delipidated microalgal biomass compared to the polymer resin may be used in an amount of 10 to 70% by weight, preferably 30 to 70% by weight, and more preferably 50% by weight.

Specifically, the biodegradable complex according to the present invention may be prepared according to the method described in FIG. 1 . A selected amount of DCB relative to the weight of chitosan (5, 10, 15, 20, 25, 30 and 35 wt %) was dispersed in 1% acetic acid and then sonicated at room temperature for 30 minutes. After complete dispersion, 2% (w/v) of chitosan can be added to each DCB dispersion, and the resulting mixture can be prepared by continuously stirring at room temperature for 24 hours. Here, as a plasticizer, glycerol may be added at a constant concentration of 20 wt% of chitosan.

In the present invention, a biodegradable film can be prepared using the biodegradable composite material. Specifically, the prepared biodegradable composite is poured into a Petri dish having an inner diameter of 90 mm, and dried at 40° C. for 24 hours to prepare a film having an average thickness of 100 ± 7 μm. The resulting film may be heat treated at 100° C. for 2 hours, and the treated film may be conditioned in a chamber at 25° C. and 50% relative humidity for 48 hours.

A polyurethane/delipidated chlorella biomass (PU-DCB) composite material can be prepared according to the method described in FIG. 7 .

For composite preparation, DCB was first vacuum dried in an oven at 60° C. for 6 hours. Then, the DCB was triturated and added to 10 mL DMSO. Then, the DCB-DMSO mixture was probe sonicated (amplitude: 50%, pulse: 50 sec/10 sec) for 30 min. The resulting DCB-DMSO solution was used for PU synthesis.

PEG 200 (2 g) was mixed with 1% (v/w) dibutyltin dilaurate in a beaker for 5 minutes at room temperature. Then, hexamethylene diisocyanate (HMDI) was added dropwise to the solution and thoroughly mixed for 5 minutes. Here, it is preferable to keep the isocyanate/hydroxyl (NCO/OH) ratio at 2:1.

Different amounts of DCB (10, 30, 50 and 70 Wt% of PEG 200 mass) are added dropwise and mixed at room temperature for 30 minutes. It can then be prepared by further diluting the resulting solution by adding DMSO before casting to a glass plate and vacuum drying at 50° C. for 5 to 8 minutes for bubble entrapment.

Then, air was injected under vacuum to avoid sample deformation. Finally, the film can be prepared by curing the sample at 80° C. for 24 hours.

By adding delipidated chlorella microalgal biomass, a biodiesel production waste, to chitosan and polyurethane as a filler, the thermal stability is improved, the tensile strength is increased from 19.6 to 67.4 MPa, and the water vapor permeability, water content and swelling are reduced. , it can be used as a material for inhibiting food photooxidation by reducing light transmittance and opacity. In addition, the resulting Cs/DCB complex can be biodegraded faster than 50% after being buried in soil for 60 days.

In addition, when the DCB content was increased, the tensile strength and elongation at break of the composite material increased from 33.85% to 115.74% and from 69.64% to 247.62%, respectively, compared with the pure PU-PEG film. When DCB was added by 70%, the antioxidant activity and hydrophilicity of the composite material were increased by 69.3% and 85%, respectively, compared to pure PU-PEG. In addition, the tensile strength, elongation at break, antioxidant, and water absorption were improved.

According to the present invention, it is possible to provide a method for manufacturing a biodegradable bioplastic such as a biodegradable composite using a delipidated microalgal biomass as a filler in chitosan or polyurethane, a film using the same, and improved physical properties thereof.

By using the biodegradable composite according to the present invention, a composite material using DCB with improved physical properties such as thermal stability, tensile strength, water vapor permeability, moisture content and expansion, light transmittance and opacity, elongation at break, antioxidant, and water absorption It can be widely applied to fields such as medical and food packaging films requiring antioxidant properties as well as existing polyurethane applications such as construction, automobiles, coatings, sealants, adhesives, foams, and composites.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the following examples are only intended to embody the contents of the present invention, and the present invention will not be limited thereby.

<Example 1> Preparation of a film comprising DCB

1-1. Preparation of delipidated chlorella biomass

Defatted chlorella biomass (DCB) was described in Yun, J.-H. It was prepared using a manufacturing method such as After harvesting the cultured Chlorella biomass and freeze-drying for 48 hours, hexane-methanol (4: 1 (v / v)) was added to the freeze-dried sample in a ratio of 10: 1 (v/w) at 60 °C, Lipids were removed by extraction overnight in a reactor with a stirring speed of 200 rpm. After centrifugation at 6000 rpm, the supernatant was removed and the resulting biomass was completely dried at 65° C. to prepare DCB.

1-2. Chitosan-Delipid Chlorella Biomass (Cs/DCB) Film Preparation

A Cs/DCB composite film was prepared according to the method described in FIG. 1 . Selected amounts of DCB relative to the mass of chitosan (5, 10, 15, 20, 25, 30 and 35 wt %) were dispersed in 1% acetic acid and then sonicated at room temperature for 30 minutes. After complete dispersion, 2% (w/v) chitosan was added to each DCB dispersion, and the resulting mixture was stirred continuously at room temperature for 24 hours. Glycerol as a plasticizer was then added to the film forming solution at a constant concentration of 20 wt % of chitosan. Each film-forming solution was poured into a Petri dish with an inner diameter of 90 mm, and dried at 40° C. for 24 hours to form a film having an average thickness of 100 ± 7 μm. Then, the resulting film was heat-treated at 100 °C for 2 hours. The treated films were then conditioned in a chamber at 25° C. and 50% relative humidity for 48 hours.

1-3. Polyurethane-Delipidated Chlorella Biomass (PU-DCB) Film Preparation

A polyurethane/delipidated Chlorella biomass (PU-DCB) composite film was prepared according to the method described in FIG. 7 . For composite preparation, DCB was first vacuum dried in an oven at 60° C. for 6 hours. Then, the DCB was triturated and added to 10 mL DMSO. Then, the DCB-DMSO mixture was probe sonicated (amplitude: 50%, pulse: 50 sec/10 sec) for 30 min. The resulting DCB-DMSO solution was used for PU synthesis.

PEG 200 (2 g) was mixed with 1% (v/w) dibutyltin dilaurate in a beaker for 5 minutes at room temperature. Then, hexamethylene diisocyanate (HMDI) was added dropwise to the solution and thoroughly mixed for 5 minutes. The isocyanate/hydroxyl (NCO/OH) ratio was maintained at 2:1. Different amounts of DCB (10%, 30%, 50% and 70% of PEG 200 mass) were added dropwise and mixed at room temperature for 30 minutes. The resulting solution was then further diluted by adding DMSO before casting to a glass plate and vacuum-dried at 50° C. for 5-8 minutes to trap air bubbles. Then, air was injected under vacuum to avoid sample deformation. Finally, the samples were cured at 80 °C for 24 h.

<Example 2> Thermal stability of the resulting film

The effect of DCB incorporation on the thermal decomposition behavior of chitosan-based films is shown in FIG. 2 . Overall, the TGA and DTG curves of pure chitosan and Cs/DCB composite films showed two-step degradation. The first weight loss occurred at 110–240 °C associated with the release of moisture and glycerol from the film matrix. A second weight loss was observed over a wide temperature range of 250 to 450 °C, which is mainly related to the degradation of chitosan and organic substances such as carbohydrates and proteins in DCB. As shown in Figure 2, a shift from the peak associated with chitosan pyrolysis to a lower temperature was shown for the Cs/DCB composite film, indicating the ability of the delipidated algal biomass to improve the thermal stability of the resulting film. This improvement in thermal stability of the Cs/DCB composite film is attributed to the strong hydrogen bond formed between DCB and chitosan along with the high thermal stability of DCB. After complete degradation, the Cs/DCB composite film showed a lower weight loss (70%) compared to the 80% weight loss of the control (pure chitosan, 0% DCB) film.

<Example 3> Mechanical properties of the resulting film

The effect of incorporating DCB in different amounts on the mechanical properties of chitosan films was investigated in terms of tensile strength (TS) and elongation at break (% E). As can be seen from FIG. 3, when the DCB content was increased to 25 wt%, the TS of the chitosan-based film was significantly increased from 19.6 to 67.4 MPa, and a decrease in % E of the chitosan film was observed with the addition of DCB. This improvement in the tensile strength of the resulting composite film can be attributed to the uniform distribution of DCB particles into the polymer matrix with the establishment of strong hydrogen bridge interactions between chitosan.

<Example 4> Water vapor permeability, water content and swelling degree

Figure 4a shows the effect of DCB incorporation at different concentrations on the water vapor permeability (WVP) of chitosan-based films. Overall, the addition of DCB significantly reduced the WVP of the Cs/DCB composite film. This reduction was more than 60% for the film incorporating 35% DCB compared to the pure chitosan film. This improvement in water vapor transmission properties can be attributed to the establishment of intermolecular hydrogen bonds between the polymer matrix and the incorporated DCB, which results in the formation of cross-linked network structures that can reduce the free volume of the polymer matrix. In addition, as the film is heat treated (100 °C for 2 h), water molecule diffusion can be greatly reduced by a crosslinking effect, which is believed to reduce the mobility of polymer chains and reduce the diffusion of water molecules through the composite film. . Similarly, as the DCB content was increased from 5 to 35%, a significant decrease in the water content and swelling degree of the Cs/DCB composite film was recorded (Fig. 4b). This improvement of the barrier properties of the Cs/DCB composite film can be attributed to the interaction between Cs and DCB molecules in which free hydrophilic moieties such as amino and hydroxyl groups can bind water.

Water vapor permeability was determined gravimetrically according to the AFNOR NF H00-030 standard method. Prior to measurement, the films were conditioned at 25° C. and 50% relative humidity for 48 hours. The pretreated film was then mounted in a cup filled with silica gel. The cups were then placed in a controlled temperature (38 ± 1 °C) and relative humidity (90 ± 3%) oven. Weights were measured at 30 minute intervals and the change in weight was recorded as a function of time. Linear regression was used to calculate slope and time plots of weight. The WVP of the film was calculated using equation (1). where the water vapor transmission rate (WVTR) is the slope/film area (g/m2 h), L is the film thickness, and Δp is the difference in partial water vapor pressure [Δp = p(RH2-RH1) = 5.942 kPa, where p is the saturated vapor pressure].

Water content (WC) and degree of swelling (SD) were measured as follows. Each film sample was cut into squares (20 x 20 mm) and weighed to obtain the initial weight (mo). Then, the film sample was dried in a hot air oven at 100° C. for 24 hours to obtain an initial film dry weight (m1). Thereafter, the film specimen was immersed in a Petri dish containing 30 mL of distilled water, covered, and left at room temperature for 24 hours. After removing the remaining water and drying, the mass was measured (m2). Three measurements were made for each film sample to calculate the average value of water content and swelling degree according to equations 2 and 3.

<Example 5> Light transmittance and opacity

The UV and visible light transmittances of chitosan films incorporating different DCB contents in the wavelength range of 200-800 nm are shown in Fig. 5a. For UV transmission (200-280 nm), increasing the DCB content from 5% to 35% significantly reduced the light transmittance of the Cs/DCB composite film compared to chitosan, indicating the ability of DCB to improve light barrier properties. Therefore, it is expected to be used as a packaging material to limit UV-induced lipid oxidation in food systems. In the case of visible light transmission (350-800 nm), the transmittance of the Cs/DCB composite film decreased significantly when the DCB content was increased. In the case of the chitosan film with the highest DCB content, a transmittance reduction of more than 90% was observed at 700 nm wavelength.

The opacity values of pure chitosan and Cs/DCB composite films are presented in Figure 5b. Overall, the films incorporated with DCB showed higher opacity values compared to the pure chitosan films. In this regard, the film with the highest DCB content exhibits the best light-shielding properties and can be used as a potential material for inhibiting food photooxidation.

<Example 6> Biodegradability

Images of chitosan and Cs/DCB composite films before and after contact with soil for 60 days are shown in FIG. 6 . Overall, the film lost its initial appearance and structural integrity, and showed a rough, eroded surface with porous pores due to the degradation of microorganisms present in the soil. The quantitative index of film biodegradability was estimated by weight loss. Regardless of the DCB content, the biodegradation rate of the Cs/DCB composite film was estimated to be more than 50% after embedding in soil for 60 days. Therefore, the resulting Cs/DCB complex can be considered as a biodegradable material due to its rapid degradation process.

<Example 7> Mechanical properties of the resulting PU-PEG/DCB film

When the DCB content was added to 10 to 50%, the tensile strength of the PU-PEG/DCB composite film was increased by 33.85-115.74% compared to the pure PU-PEG film (FIG. 8). The strength improvement of the PU-PEG/DCB composite film is due to the formation of chemical bonds and hydrogen bonds between the isocyanate groups of the PEG-HMDI prepolymer present in the medium and the hydroxyl groups of the DCB bio-filler. When DCB was added from 10% to 70%, the elongation at break was increased in the range of 69.64-247.62% compared to the pure PU-PEG film (Fig. 9). The increased flexibility of PU-PEG-based films is because the incorporation of DCB improves the smoothness and cohesiveness of the surface to retard cracking, and DCB acts as a bridge between the polymer chains creating an extension of the network throughout the PU matrix. am.

<Example 8> Antioxidant properties of the resulting PU-PEG/DCB film

The antioxidant activity of the PU-PEG/DCB composite film is shown in FIG. 10 . As the DCB content increased, the DPPH radical scavenging activity of the PU-PEG/DCB film increased. The DPPH radical scavenging activity of the pure PU-PEG film was 15%, and when DCB was added 70%, the DPPH radical scavenging activity was up to 69.3%. The improvement of the antioxidant properties of the PU film is due to the large amount of antioxidant carotenoids present in chlorella cells such as astaxanthin, canthaxanthin, lutein, beta-carotene and chlorophyll. In addition, destruction of the cell wall by probe sonication promotes the release of carotenoids from the cytoplasm, which may contribute to enhancing the antioxidant activity of PU-PEG/DCB composite films.

<Example 9> Water absorption properties of the resulting PU-PEG/DCB film

11 shows the effect of DCB content on water absorption of PU-PEG/DCB composite films. As the DCB content increased, the bulk hydrophilicity of the PU matrix increased. The water absorption percentage of the pure PU-PEG film was 15%, and when DCB was added 70%, the maximum water absorption percentage was 27%. The increase in the hydrophilicity of the PU matrix can be attributed to the presence of PEG, known for its hydrophilic properties, along with the abundance of monosaccharides such as galactose, arabinose, mannose, glucose, xylose and rhamnose in DCB. The enhancement of PU hydrophilicity can also be attributed to the abundance of —OH groups present in the polymer matrix. This result could play an important role in the hydrolysis and biodegradation of the resulting hydrophilic composites.

As described above, although specific embodiments of the present invention have been described in detail, those skilled in the art who understand the spirit of the present invention may add, change, delete, etc. other components within the scope of the same spirit, and other degenerate inventions However, other embodiments included within the scope of the present invention may be easily proposed. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention. should be interpreted as

Claims (13)

A biodegradable composite comprising a polymer resin and delipidated microalgal biomass.
According to claim 1,
The polymer resin is polyimide (PI), polyimideamide (polyimideamide), polyetherimide (PEI), polyethyleneterephtalate (PET), polyethylenenaphthalate (PEN), polyetheretherketone (polyetheretherketon, PEEK), cyclic olefin polymer (COP), polyacrylate (PAC), polymethylmethacrylate (PMMA), and triacetylcellulose (TAC), polyurethane (polyurethane, PU) at least one synthetic polymer selected from the group consisting of or at least one selected from the group consisting of hyaluronic acid, chitosan, cellulose, chondroitin sulfate, heparin, alginic acid, gelatin, collagen, dextran and dermatan sulfate A natural polymer, a biodegradable complex.
According to claim 1,
The biodegradable complex further comprises one or more plasticizers selected from glycerol, polyethylene glycol, triethyl citrate, and sorbitol.
According to claim 1,
The delipidated Chlorella microalgal biomass is a waste after biodiesel production, biodegradable complex.
According to claim 1,
The biodegradable composite has improved thermal stability, tensile strength, water vapor permeability, moisture content and swelling, light transmittance and opacity, the biodegradable composite.
According to claim 1,
The biodegradable complex is 10 to 70% by weight of the delipidated microalgal biomass relative to the high molecular weight, the biodegradable complex.
agitating a mixture containing the delipidated chlorella biomass, a polymer resin, and an acidic solution; and,
A method for producing a biodegradable composite comprising a; curing by adding a plasticizer to the mixture.
8. The method of claim 7,
The polymer resin is polyimide (PI), polyimideamide (polyimideamide), polyetherimide (PEI), polyethyleneterephtalate (PET), polyethylenenaphthalate (PEN), polyetheretherketone (polyetheretherketon, PEEK), cyclic olefin polymer (COP), polyacrylate (PAC), polymethylmethacrylate (PMMA), and triacetylcellulose (TAC), polyurethane (polyurethane, PU) at least one synthetic polymer selected from the group consisting of or at least one selected from the group consisting of hyaluronic acid, chitosan, cellulose, chondroitin sulfate, heparin, alginic acid, gelatin, collagen, dextran and dermatan sulfate A method for producing a biodegradable complex, which is a natural polymer.
8. The method of claim 7,
The plasticizer is at least one selected from glycerol, polyethylene glycol, triethyl citrate, and sorbitol, a biodegradable composite manufacturing method.
8. The method of claim 7,
The delipidated Chlorella microalgal biomass is a waste after biodiesel production, a method for producing a biodegradable complex.
A molding material comprising the biodegradable composite of any one of claims 1 to 6.
A molded article manufactured using the biodegradable composite of any one of claims 1 to 6.
13. The method of claim 12,
The molded article is one of a film, a packaging material, an adhesive, a foam, or a container.

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