CN111187493A

CN111187493A - Biodegradable tableware material and preparation method and application thereof

Info

Publication number: CN111187493A
Application number: CN202010111013.1A
Authority: CN
Inventors: 王选伦; 涂良浩; 刘玲; 陈师岐
Original assignee: Chongqing University of Technology
Current assignee: Chongqing University of Technology
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2020-05-22

Abstract

The invention discloses a biodegradable tableware material, which comprises the following components in parts by weight: 100 parts by weight of PBS and 1-5 parts by weight of organic nano clay. The biodegradable tableware material can improve the mechanical property, the processing property and the mechanical property of PBS and enlarge the application range of PBS on the premise of ensuring the thermal property of PBS. The invention also discloses a preparation method and application of the biodegradable tableware material, and the preparation method is simple in process flow and suitable for large-scale industrial production.

Description

Biodegradable tableware material and preparation method and application thereof

Technical Field

The invention relates to a high polymer material, in particular to a biodegradable tableware material and a preparation method and application thereof.

Background

China is a large country for consuming disposable tableware, disposable catering has wide market prospect, wealth is created from a foam lunch box to disposable wooden chopsticks, and from a disposable paper lunch box to sterilized tableware, and consumption crisis and sanitary environmental protection problems are caused once and again. From the middle of the 80 s, disposable tableware is gradually emerging, and foam tableware which cannot be degraded appears early, so that a great amount of white pollution is caused. The white pollution damages the ecological environment to a certain extent, so that large-area green vegetation cannot grow and the social environment is greatly stressed.

It has been found that if at least 2000 million disposable tableware are discarded daily throughout the country in terms of the amount produced only by the consumer, most of them eventually become garbage due to a poor channel for recycling of renewable resources, and have to be disposed of in landfills or incinerated. The pollution problem caused by taking out disposable tableware is a problem which must be looked upon from the perspective of energy waste and the perspective of increasing the running burden of cities and the risk of environmental pollution. Therefore, there is a need to develop a degradable composite material suitable for tableware.

Under the environment with large demand, people pay attention to biodegradable high polymer materials. The biodegradable high polymer material is very environment-friendly, and the quantity of waste plastics and the pollution to the environment can be reduced by replacing the common high polymer material with the biodegradable high polymer material. However, the research on the biodegradable polymer material is not much, so the biodegradable polymer material has good development prospect and research significance.

Poly (butylene succinate) (PBS) is obtained by condensation polymerization of succinic acid and butanediol, and has white color and no odor, because it is easily decomposed and degraded by some microorganisms or enzymes in natural state, and only CO remains₂And H₂O, so PBS is a completely biodegradable polymer material and is very representative. It is widely available, can be used as petroleum mineral resource, and can also be used as a substitute for petroleum mineralObtained by biological enzyme fermentation. In addition, PBS also has better biocompatibility and bioabsorbability, so the PBS has certain application in the medical field. The melting point of PBS is higher than that of other biodegradable materials, generally around 114 ℃, and the crystallinity of PBS varies due to the difference in molecular weight and molecular weight distribution, but is usually between 30% and 45%.

PBS is one of biodegradable polymer materials, has good mechanical properties, higher use temperature and slightly lower price compared with other degradable polymers, but has some differences with traditional polymer materials such as plastics, rubber and the like.

Disclosure of Invention

The invention aims to provide a biodegradable tableware material, a preparation method and application thereof, which can improve the mechanical property, the processability and the mechanical property of PBS and enlarge the application range of the PBS on the premise of ensuring the thermal property of the PBS.

The biodegradable tableware material comprises the following components in parts by weight: 100 parts by weight of PBS and 1-5 parts by weight of organic nano clay.

Further, the biodegradable tableware material comprises the following components in parts by weight: 100 parts by weight of PBS, 5 parts by weight of organized nanoclay.

Further, the organic nano clay is organic nano montmorillonite.

A method for preparing biodegradable tableware material, which comprises the following steps:

weighing 100 parts by weight of PBS and 1-5 parts by weight of organic nano clay, and blending for 1min in a high-speed mixer to obtain a blended material;

step two, adopting a double-screw extruder to melt and extrude the blended material, and then granulating by a granulator to obtain granules;

the temperature of each zone of the double-screw extruder is as follows: the processing parameters of the double-screw extruder are as follows: the temperature of the first area is 90-110 ℃, the temperature of the second area is 100-120 ℃, the temperature of the third area is 105-125 ℃, the temperature of the fourth area is 105-125 ℃, the temperature of the V-IX area is 110-130 ℃, the temperature of the machine head is 110-130 ℃, and the temperature of the blending material is 110-130 ℃;

step three, placing the granules into a double-screw injection molding machine for injection molding, wherein the injection molding process parameters are as follows: the nozzle temperature is 120-140 ℃, the first-stage temperature is 130-150 ℃, the second-stage temperature is 130-150 ℃, the third-stage temperature is 115-135 ℃, the fourth-stage temperature is 20-40 ℃, the injection pressure is 10-50 MPa, the pressure maintaining pressure is 10-50 MPa, and the cooling time is 10-60 s. The control of the cooling time is very important because the plastic product can be successfully demolded when being cooled and solidified to a certain rigidity, the short cooling time can be influenced by external force to generate deformation in the demolding process, the appearance and the mechanical property of the product are influenced, and the long cooling time can cause the material at the nozzle to be cooled and block the nozzle.

Further, the PBS is dried in an oven before blending in the first step, wherein the drying temperature is 50-70 ℃, and the drying time is 7-9 hours.

Further, in the second step, the screw rotating speed of the double-screw extruder is 100-500 r/min, and the screw rotating speed of the granulator is 150-600 r/min.

The biodegradable tableware material or the application of the prepared biodegradable tableware material as disposable tableware ensures that the disposable tableware is very easy to be decomposed and degraded by some microorganisms or enzymes in a natural state, and finally only CO is left₂And H₂O, the pollution to the environment is avoided, and the composite material has better performance after the modification of the organic nano clay, thereby enlarging the application range of the PBS in the disposable tableware.

Compared with the prior art, the invention has the following beneficial effects.

1. The invention takes PBS and organized nano clay as raw materials, the organized nano clay is uniformly dispersed in the PBS through melt blending to obtain the biodegradable tableware material, the molecular interaction of the organized nano clay and the PBS matrix achieves the modification purpose, the crystallinity and the crystallization rate of the biodegradable tableware material are improved, the crystal growth in the material is more complete, meanwhile, the melting temperature and the Vicat softening point of the material are basically unchanged, and the normal use of the composite material is not influenced. In addition, on the aspect of mechanical property, the tensile strength of the biodegradable tableware material obtained by modifying PBS through the organic nano clay is obviously improved, although the impact strength is reduced, the brittle fracture is shown, the organic nano clay has strong chemical enhancement but not toughening on the PBS, and accordingly, the application range of the biodegradable tableware material can be further determined. And with the addition of the organized nano clay, the complex viscosity and the storage modulus of the biodegradable tableware material are both reduced, the flowing property of the material is improved, the processing property of the material is further improved, and the production and the manufacture of the biodegradable tableware material are facilitated.

2. The preparation method of the invention limits the material blending time and the parameters of melt extrusion and injection molding, ensures that the organized nano clay can be uniformly dispersed in PBS, has simple process flow and is suitable for large-scale industrial production.

Drawings

FIG. 1 is a DSC crystallization curve of biodegradable tableware material obtained in the control group and examples one, two, three, four and five;

FIG. 2 is a DSC melting curve diagram of the biodegradable tableware material obtained in the control group and examples one, two, three, four and five;

FIG. 3 is a bar graph of tensile strength of biodegradable tableware material obtained in control group and examples one, two, three, four and five;

FIG. 4 is an SEM photograph of the biodegradable tableware material obtained in the control group and examples I, II, III, IV and V;

FIG. 5 is a graph showing the Vicat softening temperatures of biodegradable tableware materials obtained in control groups and examples I, II, III, IV and V;

FIG. 6 is a graph of complex viscosity versus frequency for biodegradable tableware materials obtained in control and examples one, two, three, four and five;

FIG. 7 is a graph showing the change of storage modulus with frequency of the biodegradable tableware material obtained in the control group and examples I, II, III, IV and V.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings.

The PBS of the present invention was purchased from Pasteur engineering plastics, Germany, under the designation H1200. The main equipment and instruments involved in processing and detecting the material of the invention include:

electric heating air blast drying oven: Shanghai-Hengchun scientific instruments, Inc. with model number BPG-9070A;

electronic balance counter balance: ruian City Ant weighing apparatus Co., Ltd, model number LQ-6 kg;

co-rotating twin-screw extrusion granulator: the model number of the Nanjing Ruiya Foster high polymer equipment company is TSE-30A/500-11-40;

plastic injection molding machine: towa machinery, Inc., model TTI-95G;

high-speed mixer: jiangsu white bear GmbH, model number SHR-10;

microcomputer control electronic universal tester: the Meister Industrial systems, Inc., model number CMT 6104;

notch sampling machine: the model of the Jinjian detection instrument company, Inc. of Chengde city is JJANM-11;

pendulum impact tester: shenzhen Wanyun Experimental facilities, Inc., model number PIT 501J;

differential scanning calorimeter: TA, Inc. USA, model Q20;

rotating the rheometer: TA corporation, usa, model AR1500 ex;

scanning electron microscope: japanese electronic corporation, model JSM-6460 LV.

The raw material ratios of the first, second, third, fourth and fifth examples are shown in Table 1.

TABLE 1 example raw material ratios of first, second, third, fourth and fifth

	PBS/parts by weight	Organized nanoclay per part by weight
			Example one	100	1
Example two	100	2
			EXAMPLE III	100	3
Example four	100	4
			EXAMPLE five	100	5

Nanoclay refers to layered silicate mineral particles having a nano-size. Nanoclays can be classified into several classes, such as montmorillonite, bentonite, kaolin, hectorite and halloysite, depending on the chemical composition and morphology of the nanoparticles. The organic nano montmorillonite is preferably used, is the most common nano clay in material application, and has the advantages of easily obtained raw materials and low cost. A general method of organizing nanoclays is to surface treat the nanoclays with organic modifiers such as cationic surfactants, anionic surfactants, nonionic surfactants, polymeric monomers or coupling agents. For example, a cation exchange reaction occurs by treating montmorillonite with a cationic surfactant, cetyltrimethylammonium bromide, and octadecyltrimethylammonium chloride. Organic groups are made to cover the surface of montmorillonite or to be inserted between layers, so that the surface energy is changed, the interlayer spacing is increased, and the original hydrophilicity is changed into lipophilicity. It is to be noted that the organized nanoclays of examples one, two, three, four, and five were obtained from commercial sources.

The method for preparing a biodegradable tableware material according to the first embodiment comprises the following steps:

step one, weighing 100 parts by weight of PBS and 1 part by weight of organic nano clay, and blending for 1min in a high-speed mixer to obtain a blended material; and drying the PBS in an oven before blending, wherein the drying temperature is 60 ℃, and the drying time is 8 h.

And step two, adopting a double-screw extruder to melt and extrude the blended material, and then granulating by a granulator to obtain granules.

The temperature of each zone of the double-screw extruder is as follows: the processing parameters of the double-screw extruder are as follows: the temperature of zone I is 100 ℃, the temperature of zone II is 110 ℃, the temperature of zone III is 115 ℃, the temperature of zone IV is 115 ℃, the temperature of zone V-IX is 120 ℃, the temperature of a machine head is 120 ℃, and the temperature of the blending material is 120 ℃.

It should be noted that before extrusion granulation, the twin-screw extruder is cleaned by using high-density polyethylene HDPE at about 170 ℃, the twin-screw extruder is cleaned and then cleaned by adding pure PBS, and after cleaning, the temperature is reduced to the melt extrusion temperature, and then extrusion blending can be performed. After the PBS/organized nano clay composite material can be normally extruded, a blower and a granulator are started, wherein the blower is mainly used for blowing and drying moisture on the PBS/organized nano clay composite material. The rotating speed of the granulator needs to be matched with that of the extruder, the spline diameter is thinned or broken when the rotating speed of the granulator is too high, and the spline is accumulated when the rotating speed is too low.

The rotating speed of the screw of the double-screw extruder is 110r/min, the rotating speed of the screw of the granulator is 180r/min, and the rotating speeds of the screw and the granulator are matched with each other, so that the smooth extrusion of granules is ensured.

And step three, placing the granules into a double-screw injection molding machine for injection molding, cleaning the double-screw injection molding machine by adopting high-density polyethylene HDPE at about 170 ℃ before injection molding of the granules, placing pure PBS for cleaning after the double-screw injection molding machine is cleaned, and then cooling to the injection molding processing temperature after cleaning, and then performing extrusion blending.

The injection molding process parameters are as follows: the nozzle temperature is 130 ℃, the first-stage temperature is 140 ℃, the second-stage temperature is 140 ℃, the third-stage temperature is 155 ℃, the fourth-stage temperature is 29 ℃, the injection molding pressure is 25MPa, the pressure maintaining pressure is 35MPa, the cooling time is 30s, and the whole injection molding cycle is about 1 min. The control of the cooling time is very important because the plastic product can be successfully demolded when being cooled and solidified to a certain rigidity, the short cooling time can be influenced by external force to generate deformation in the demolding process, the appearance and the mechanical property of the product are influenced, and the long cooling time can cause the material at the nozzle to be cooled and block the nozzle. Finally obtaining the dumbbell-shaped finished product

The preparation methods of the second, third, fourth and fifth embodiments are the same as the first embodiment.

EXAMPLE six differential scanning calorimetry was performed on the finished product and control obtained in examples one-five, respectively, using pure PBS as a control, and all samples were tested on a TA-Q20 model differential scanning calorimeter under conditions of high purity nitrogen N₂Protective State, sample N₂The atmosphere was 50 ml/min. The method is characterized in that 6 groups of materials are required to be cut into small particles with the weight of 3-5 mg before the test, the temperature is required to be raised and then lowered during the test, and the program in the differential scanning calorimetry test is set as follows: the temperature rising speed of the slope is 10 ℃/min to 180 ℃, and the end point 1 of the marking period is marked; the temperature reduction speed of the slope is between 15 ℃/min and 25 ℃, and the end point 2 of the period is marked; the temperature rising speed of the slope is 10 ℃/min to 180 ℃, and the end point 3 of the marking period is marked; the ramp rate was from 15 c/min to 25 c and the test results are shown in table 2, fig. 1 and fig. 2.

TABLE 2 melting and crystallization of biodegradable tableware materials obtained in control group and examples one, two, three, four and five

	T_c，1/℃	T_c/℃	ΔH_c/(J/g)	T_m，1/℃	T_m/℃	ΔH_m/(J/g)
							Control group	69.44	66.17	60.54	102.85	110.21	55.17
Example one	75.25	70.51	60.90	102.63	110.72	55.38
							Example two	75.61	71.17	61.62	102.26	110.12	56.02
EXAMPLE III	76.48	72.43	61.32	101.74	110.33	56.24
							Example four	76.00	71.38	63.29	102.29	110.16	57.88
EXAMPLE five	75.44	70.49	66.46	102.13	110.55	57.18

In Table 2, T_c,1Is the crystallization onset temperature, T_cIs the crystallization temperature,. DELTA.H_cIs the enthalpy of crystallization exotherm, T_m,1Is the melting onset temperature, T_mIs the melting temperature,. DELTA.H_mIs the heat of fusion absorption.

Referring to fig. 1, the crystallization starting temperature and the crystallization temperature of the biodegradable tableware materials of examples one, two, three, four, and five were shifted to the right as compared to the control group, and the peak widths of the biodegradable tableware materials became narrow and long, indicating that the crystallization temperature became high and the crystal growth was more complete, indicating that the addition of the organized nanoclay has a heterogeneous nucleation effect, causing PBS to crystallize at a higher temperature.

Referring to fig. 2, an exothermic peak appears near the melting point of pure PBS and biodegradable tableware material, which indicates that two situations may occur in the process, namely, a recrystallization phenomenon and a crystal transformation of PBS during melting, wherein PBS has α crystal form and β crystal form, α crystal form appears during static melt crystallization, but β crystal form appears only when the material is stressed, and the transformation to α crystal form occurs after the stress disappears, and usually, only α crystal form appears in DSC test, thus showing that the recrystallization phenomenon occurs in the process.

The appearance of a small exothermic peak may be that during the first crystallization, some regions in PBS may not be effectively nucleated, thereby affecting the crystallization behavior in these regions. When the temperature of the already crystallized PBS is raised to a temperature not higher than the melting point, the crystal regions of perfect crystals do not start to melt, and these crystal regions may serve as initiation points for crystallization of the non-crystallized segment, and crystals may be formed by heterogeneous nucleation at a temperature near the melting point, so that a small exothermic peak is exhibited in the DSC curve. While the organized nanoclay was successfully intercalated into the PBS as the organized nanoclay was added and dispersed in the PBS. The increase in the area of the exothermic peak is seen in the DSC curve, indicating that the organized nanoclay has heterogeneous nucleation effects, resulting in a higher degree of crystallinity and crystallization rate of the biodegradable tableware material than the neat PBS.

As is clear from the data in Table 2, the melting temperatures of the biodegradable tableware materials obtained in the control group and the first, second, third, fourth and fifth examples were substantially the same, and the melting temperature did not increase with the increase in the amount of the organized nanoclay in PBS at about 110 ℃. Examples first, second, third, fourth, and fifth, biodegradable tableware materialsCrystallization exothermic heat content delta H of material_cThe heat absorption enthalpy of fusion is increased all the time compared with the control group_mHas also been increasing.

The crystallinity is proportional to the heat absorption enthalpy of fusion Δ H of the polymer_m，ΔH_mThe larger the polymer, the greater the crystallinity of the polymer. As can be seen from the data in table 2, the crystallinity of the biodegradable tableware material increases as the fraction of organized nanoclay increases.

The crystallization rate can be expressed by the degree of supercooling, which is T_m-T_cThe smaller the supercooling degree value, the faster the crystallization rate. From the data in Table 2, it can be seen that the crystallization rate of the biodegradable tableware material is also greatly improved.

In the seventh embodiment, the finished products obtained in the first to fifth embodiments and the control group are respectively subjected to tensile strength analysis by using pure PBS as a control group, and then are respectively subjected to tensile property test by using a microcomputer controlled universal tester of CMT6104 model number, china ltd. The 11CM long spacing was drawn on the article before testing. Putting the dumbbell-shaped product according to the test steps, controlling the parameter setting of the universal tester by a microcomputer: the distance between the clamps was 110mm, the stretching rate was 50mm per minute, and the test temperature was room temperature. And testing 5-6 sample strips by each group of materials, and taking the average value of the results to make a tensile strength bar chart in order to obtain more accurate data.

Referring to fig. 3, the tensile strength of the control group, i.e., pure PBS, was 32.16MPa, and the tensile strength of the biodegradable tableware material was improved to some extent compared to the pure PBS, which indicates that the organized nanoclay was dispersed in the PBS by melt blending and improved the mechanical properties of the PBS, but the fracture mode thereof still showed brittle fracture. The highest tensile strength of the biodegradable tableware material was 34.24MPa in the fifth example, which is increased by 2.08MPa compared with the pure sample, and the lowest tensile strength was 33.62MPa in the first example, which is increased by 1.46MPa compared with the pure sample. There is a rule that the tensile strength of the entire pattern is greater as the fraction of the organized nanoclay increases. In general, the tensile strength of the biodegradable tableware material is improved well, the modified product can meet higher requirements of people, and the application of PBS in life and work is expanded.

Example eight, the finished products obtained in examples one to five and the control group were subjected to impact strength analysis using pure PBS as a control group, respectively, and the products were cut into bars having a length of 80mm, a width of 10mm and a thickness of 4mm, and the bars were ground to have notches of 2 mm. Before the cantilever beam impact tester is used, the angle needs to be zeroed, the impact parameters are set to be 8mm multiplied by 4mm multiplied by 2mm, samples are placed on the pendulum impact tester for impact performance testing, each group of samples are tested for 5 sample strips, and finally the average value is taken, and the results are shown in table 3.

TABLE 3 table of impact strength values of biodegradable tableware materials obtained in the control group and examples I, II, III, IV and V

Group of	Control group	Example one	Example two	EXAMPLE III	Example four	EXAMPLE five
							Notched impact strength (kJ/m)²)	8.19	5.87	6.34	6.35	7.20	7.35

As can be seen from Table 3, the impact strength of the control, i.e., the virgin PBS, was 8.19kJ/m²While the biodegradable tableware materials obtained in examples one to five all had a decreased notched impact strength, the impact strength of the biodegradable tableware materials gradually increased with the increase of the amount of the organized nanoclay, and the impact strength was 7.35kJ/m when 5 parts of the organic nanoclay was added²The maximum impact strength in the biodegradable cutlery materials of examples one to five is slightly reduced compared to pure PBS. The decrease in impact strength of the biodegradable tableware material should be such that the dispersion effect of the organized nanoclay in PBS is not particularly desirable and agglomeration may occur. The precondition for the organized nanoclay-modified PBS is that the nanoclay is completely exfoliated or uniformly dispersed in the PBS matrix, but the organized nanoclay is hydrophilic, resulting in a lower degree of exfoliation and poor molecular interaction with the PBS polymer matrix and therefore poor performance. However, as the number of parts of the organized nanoclay increases, although the organized nanoclay may be agglomerated due to dispersion problems, since the increased number of the organized nanoclay may make the probability of dispersion or exfoliation of the organized nanoclay with PBS greater, the notched impact strength of the biodegradable tableware material increases as the number of parts of the organized nanoclay increases.

In the ninth embodiment, in order to observe the dispersion of the organized nanoclay in the biodegradable tableware material in the PBS matrix, the surface morphology of the finished product obtained in the first to fifth embodiments and the control obtained in the first to fifth embodiments was analyzed using pure PBS as a control, and the microscopic cross-sectional morphology of the biodegradable tableware material obtained in the control and the first to fifth embodiments was observed using a scanning electron microscope SEM. The sample is firstly manufactured into a 2mm gap, and then a pendulum impact tester is used for manufacturing an impact section to manufacture a small sample which is 1cm away from the gap. And spraying gold to observe the section of the sample, and finally placing the sample into a scanning electron microscope for testing.

Referring to FIG. 4, the control, pure PBS, was brittle and therefore had a partially human-shaped filament in cross section. The organized nanoclay exhibits a sheet structure under a 1000-fold microscope, the organized nanoclay with a layered structure can be observed in the SEM images of examples one, three, four, and five, and the organized nanoclay in the SEM images of examples three, four, and five is better dispersed than the SEM image of example one, while the delamination phenomenon in the SEM image of example two is less obvious, but the mechanical property analysis thereof is combined to show that the organized nanoclay of example two is still dispersed in PBS.

In the tenth example, the finished products obtained in the first to fifth examples and the control group were subjected to vicat softening point analysis using pure PBS as a control group, vicat softening point temperatures of the control group and the finished products obtained in the first to fifth examples were measured using a thermal deformation and vicat softening point temperature tester, and the samples were prepared into square blocks of 20mm × 20mm × 4mm using a force of 50N and a heating rate of 120 ℃/h using silicone oil as a heat transfer medium. Zero-setting was required before the start of each experiment, the initial temperature of the test was room temperature and the results are shown in figure 5.

Referring to fig. 5, the control, pure PBS, had the highest vicat softening point of 86.8 ℃, and the vicat softening temperature of the biodegradable tableware material was slightly lower than that of the pure PBS, but the vicat softening point was not greatly changed as a whole. Of the biodegradable tableware materials, the Vicat softening point was highest in example three, the temperature was 86.7 ℃ and lowest in example four, the temperature was 85.5 ℃. In the experiment, the difference between the Vicat softening point temperature of the biodegradable tableware material and the pure PBS is 1.3 ℃ at most, the application range of the PBS is generally not influenced, the fact that the tensile property of the PBS is improved after the PBS is modified by the organic nano clay is proved, the Vicat softening temperature is hardly reduced and can meet the normal use requirement of people at the temperature of more than 85 ℃.

In the eleventh embodiment, the finished product obtained in the first to fifth embodiments and the control group are subjected to dynamic rheological property test respectively by using pure PBS as a control group, the sample is processed into a square shape of 20mm × 20mm × 4mm, the temperature of the rotational rheometer is raised to 150 ℃, the sample is placed on a rotational rheometer plate to be heated, the setting procedure is a flat steel plate clamp, the scanning test frequency is 0.01Hz to 100Hz, the test distance is 1000um, and the test strain rate is 1%, and the result is shown in fig. 6 and 7.

Referring to fig. 6, the complex viscosity of the neat PBS and the biodegradable tableware materials of examples one-five decreased with increasing frequency, showing typical shear-thinning flow behavior. This phenomenon can be explained by the theory of entanglement: at sufficiently small shear rates, the polymer is in a highly entangled pseudo-network structure with a high resistance to flow. At this point the shear rate is small and the entangled structure, although destroyed, is at a rate equal to the rate of formation, so the viscosity remains at a constant maximum, as exhibited by the flow behavior of newtonian fluids; when the shear rate is increased, the polymer molecular chains are subjected to conformational change under the action of shear, begin to be disentangled and oriented along the flow direction, the entanglement breaking speed is higher than the forming speed, so that the viscosity is reduced along with the increase of the shear rate, and the flow behavior of the pseudoplastic fluid is shown.

The storage modulus represents the energy stored by the polymer due to elastic deformation during deformation, and it can be seen from fig. 7 that the storage modulus of the pure PBS and the biodegradable tableware materials of examples one to five increases with increasing frequency, because the relaxation time of the polymer becomes relatively shorter and more elasticity is exhibited with increasing frequency, so the storage modulus increases.

The composite viscosity and the storage modulus of the biodegradable tableware material are reduced compared with pure PBS, which shows that when organic nano clay is dispersed into the PBS, the molecular chain structure of the PBS is changed, physical entanglement and chemical entanglement exist among PBS molecular chains, the physical entanglement is mainly used, and the intermolecular interaction force is mainly Van der Waals force. The addition of the organized nano clay reduces intermolecular force, so that the complex viscosity and the storage modulus of the biodegradable tableware material are reduced, the flowing property of the biodegradable tableware material is improved, the processing property of the material is further improved, and the production and the manufacture of the biodegradable tableware material are facilitated.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A biodegradable tableware material is characterized by comprising the following components in parts by weight:

100 parts by weight of PBS and 1-5 parts by weight of organic nano clay.

2. The biodegradable tableware material according to claim 1, which comprises the following components in parts by weight: 100 parts by weight of PBS, 5 parts by weight of organized nanoclay.

3. Biodegradable cutlery material according to claim 1 or 2, characterized in that: the organic nano clay is organic nano montmorillonite.

4. A preparation method of biodegradable tableware material is characterized by comprising the following steps:

step three, placing the granules into a double-screw injection molding machine for injection molding, wherein the injection molding process parameters are as follows: the nozzle temperature is 120-140 ℃, the first-stage temperature is 130-150 ℃, the second-stage temperature is 130-150 ℃, the third-stage temperature is 115-135 ℃, the fourth-stage temperature is 20-40 ℃, the injection pressure is 10-50 MPa, the pressure maintaining pressure is 10-50 MPa, and the cooling time is 10-60 s.

5. The method for preparing a biodegradable tableware material according to claim 4, wherein: and (3) drying the PBS in an oven before blending in the step one at the drying temperature of 50-70 ℃ for 7-9 h.

6. The method for preparing a biodegradable tableware material according to claim 4, wherein: and in the second step, the screw rotating speed of the double-screw extruder is 100-500 r/min, and the screw rotating speed of the granulator is 150-600 r/min.

7. Use of a biodegradable cutlery material as claimed in any of claims 1 to 3 or as prepared in any of claims 4 to 6 as disposable cutlery.