Study on Properties of Starch-Polyethylene Biodegradable Plastic Film

[Abstract]: The starch-polyethylene biodegradable film and general plastic film PE and CPP were used as materials, and the physical properties and mechanical properties were studied. The research shows that the degradation rate of the degraded materials used in the test is greater than 20% within 20-30 days; the water absorption and permeability are higher than those of the general-purpose films PP and CPP; the mechanical properties can meet the requirements. At the same time, the application prospect of biodegradable films in the packaging field was analyzed.

Keywords: biodegradable film; general plastic film; physical properties; mechanical properties; packaging application

Since the advent of the last century, plastics have penetrated into various fields such as industry, agriculture, national defense, and daily life, just like metal, glass, and paper materials, because of its small specific gravity, simple production process, wide variety of products, and attractive appearance. According to statistics, the annual output of plastics in the world today has exceeded 200 million tons, of which 30% is used for packaging, ranking first in plastic applications. With the rapid development of the commodity economy, the demand for plastic packaging materials and containers has been increasing year by year, and the problem of environmental pollution has also emerged. Because plastic packaging is mostly a kind of short life cycle goods, especially disposable packaging, such as plastic bags, plastic boxes, plastic cups, plastic wrap, milk and sour milk bags, product composite bags, etc., after sales From commodity to garbage, the quantity of plastic waste increased dramatically. Plastic waste is light in weight, large in size, and has many varieties. Collection, sorting, and disposal are extremely difficult. At the same time, it will not disappear on its own in a short period of time. If you want to naturally decompose it into simple non-pollution molecules such as CO2, H2O, etc., it will take a long period of 20 years or as long as a hundred years. At present, plastic waste is accumulating in the natural world at a rate of 25 million tons per year, which has seriously polluted the living environment of humans, animals and plants, and has become a worldwide public hazard. As a result, more and more scientists advocate the development and application of degradable plastics. As a new member of the plastics family, its emergence not only expands the function of plastics, but also alleviates and inhibits the environmental contradictions to a certain extent. Its development has become the world The research and development hotspot is seen as an ideal way to solve this worldwide problem.

At present, the industrialized degradable plastics include photodegradation, light/biodegradation, and biodegradation. Among them, biodegradable plastics that are environmentally friendly and ecologically beneficial are the most widely used ones at present, especially for moderately priced and processed equipment. The characteristics of simplicity, excellent degradability, etc., have become the most ideal materials for disposable packaging that is currently easy to recycle, and it has a very broad application prospect in the packaging field. This article intends to take starch-polyethylene biodegradable film as the research object, according to the basic requirements of the packaging, through the study of its physical properties, mechanical properties and analysis, in order to demonstrate its more ideal application in the packaging field.

1, test materials and test methods

1.1 Test Raw Materials and Reagents

Raw materials: commercially available 3 different thicknesses of starch. Polyethylene biodegradable film and PE film, CPP film a total of five kinds of test materials. The starch content of the degradable film was greater than 40%.

Reagents: HCl analytical grade, NaOH analytical grade, Na2CO3 analytical grade.

1.2 Test Methods

Combined with the basic requirements for the application of plastic film in the packaging field, this study involved a total of physical and mechanical performance tests. For ease of differentiation during the test, the 3°C degradable membranes were numbered F1, F2, and F3.

1.2.1 Determination of water absorption
According to GB1034-70 standard, using stainless steel constant temperature water bath, the 100mm × 100mm sample pretreatment, and immersed in distilled water at 20 ± 2 °C, respectively, after immersion for 24h, using an electronic balance weighing and calculating the unit area of ​​the film Water absorption and water absorption.

1.2.2 Determination of moisture permeability

According to the GB1037-87 standard, a moisture permeability tester manufactured by Japan Toyo Seiki was used to maintain a certain vapor pressure on both sides of the specimen under the specified conditions of temperature and humidity, and measure the amount of water vapor passing through the specimen.

1.2.3 Determination of tensile properties

According to the GB13022-91 standard, an AG-5000A electronic universal testing machine manufactured by Shimadzu Corporation of Japan is used. Under the specified temperature and test speed, a dumbbell-shaped standard sample is subjected to tensile load in the longitudinal direction to damage it, and the test is performed. The maximum load at break and the distance between the reticle changes, resulting in tensile strength and elongation at break.

1.2.4 Determination of Right-Angle Tearing Strength

Based on: HG2-167-65 standard, sampling in vertical and horizontal directions. An AG-5000A electronic universal testing machine manufactured by Shimadzu Corporation was used to apply a tensile load to a standard sample. The sample was torn from a right angle and the maximum load per unit thickness was obtained, that is, the right-angled tear strength. .

1.2.5 Degradation performance test

200 mg of degraded film chips were mixed with 400 g of the test soil and placed in a 1000-mL jar. A small beaker was placed on the soil. The beaker contained 20 mL of calibrated NaOH solution and the stopper was closed with a rubber stopper. After a constant temperature of 24 days at 30° C., a certain amount of NaOH solution was taken out and titrated with a known concentration of HCl solution, and the amount of released CO 2 was calculated to indicate the degree of degradation of the degradable film after the soil burial test, that is, the test biodegradable film. The degradability. (to be continued)