Development of polypropylene plastic bottle for in

Development of polypropylene plastic bottles for industrialized cultivation of edible fungi (Part 1)

I. overview

in recent years, due to the strong support of the state for modern agriculture, agricultural science and technology have developed rapidly. Agricultural products have changed the past situation of relying on climate and relying on nature, and are developing in the direction of artificial cultivation and industrialized production. The polypropylene plastic bottle and cap studied in this project are the cultivation instruments used in the industrialized production of edible mushroom Flammulina velutipes. As an ideal "green" food, Flammulina velutipes, an edible fungus, requires a lower temperature in artificial cultivation. It can only be planted in cold winter seasons, and it is listed in winter and spring seasons, with strong seasonality. In order to realize perennial production and balanced listing, scientific and technological personnel have researched and developed the factory production form of flow operation. The development of agricultural science and technology is combined with the development of science and technology in other fields. The successful development of this project is also an example of the combination of chemical products and agricultural products

Shanghai Pudong tianchu Mushroom Industry Co., Ltd., located in Shanghai Pudong Sunqiao Modern Agricultural Development Park, was established in 1999. Its industry is the industrialized production of edible mushroom Flammulina velutipes. The production line is characterized by high automation, low labor intensity and high production efficiency. The main tooling used in the whole production line is cultivation bottles. Flammulina velutipes are all produced in three-dimensional cultivation in bottles

II. Technical requirements for cultivation bottles

according to the requirements of industrialized production: 16 plastic bottles are packed in a basket, 12000 bottles are used to fill the culture medium through the assembly line every day, and the medium is sterilized and boiled at 120 ℃ for 4 hours; Point strains; Enter the cultivation room with a low temperature of 3 ℃ and a humidity of 75%. Within two months of cultivation, it is also necessary to use a scratch machine to remove the old strain blocks

based on the requirements of the above process flow, the plastic bottle should meet the following technical requirements:

1. it has a certain toughness, that is, it has high impact strength and low collision damage rate on the assembly line

2. It can withstand 120 ℃ high temperature and damp heat cooking without deformation under load-bearing conditions

3. it can withstand long-term use in low temperature and humid environment

4. In the production process, it is necessary to often observe the differentiation and reproduction of bacteria, and there are certain requirements for the transparency of bottles

5. According to the requirements of the demander, the plastic bottle is steamed every two months and used repeatedly, with a service life of 5 years

6. The cap structure requires ventilation and can filter miscellaneous bacteria

7. The material should be suitable for the processing requirements of cultivation bottles

8. as an industrial project, it is required to lower the economic cost of the relevant district governments)

III. research content

polypropylene has low price and general formability. Enterprises have done mechanical property experiments. Aluminum hydroxide is the flame retardant with the largest sales of inorganic hydroxide. Physical experiments and chemical experiments are good, and it is widely used in daily life and packaging fields. However, the general polypropylene plastic is a high crystalline polymer, and the melt crystallization speed is slow in the processing process, which is easy to form spherulites, thus affecting the impact strength of products. In addition, due to the hydrogen atom connected to the tertiary carbon atom in its structure, it is particularly sensitive to oxygen and easy to be oxidized and degraded, especially in a humid or cold environment, it will lose its use value in a few months. Moreover, the heat-resistant temperature of ordinary polypropylene is generally about 100 ℃, and the temperature it bears under high load is lower, which obviously cannot meet the technical requirements of Flammulina velutipes cultivation bottles. It is an effective way to modify polypropylene to improve its mechanical properties, thermal properties and even optical properties, improve its service life and meet the requirements of cultivation bottles

adding nucleating agent is the most effective method to modify pp. in the research of this project, we adopted the method of adding nucleating agent and stabilizer to meet the requirements of cultivation bottles

1. selection of nucleating agents

there are many kinds of PP nucleating agents, which can be divided into α Nucleating agent and β Nucleating agent. According to different structures, it can be divided into inorganic and organic. Because inorganic nucleating agents will affect the transparency of cultivation bottles, we didn't choose them. We choose two organic nucleating agents, a and B, and mix them according to a certain formula, The results are as follows:

Table 1 Effect of nucleating agent on mechanical properties of PP

normal align = center> nucleating agent

normal align = center> tensile strength (MPA)

normal align = center> elongation at break (%)

normal align = center> notch impact strength (kj/m2)

normal align = center> no nucleating agent

normal align = center er>34.0

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