Greenhouse film is a special plastic film used for agricultural production and construction of facilities, and the main use is to cover greenhouses for professional vegetable planting in various places to improve the product and quality of vegetables. It can promote the growth of greenhouse crops, increase yield and income, light transmittance, heat preservation, tensile resistance and aging resistance are better than ordinary agricultural film.
The quality of greenhouse film can be seen from the aspects of anti-fog fluidity, anti-aging tensile performance, transparency, and heat preservation. The quality of the shed film can be judged by the following identification:
1. Appearance identification of greenhouse film. By carefully observing the appearance of the greenhouse film, it is possible to preliminarily identify the category of greenhouse film plastic: thermoplastic, thermosetting or elastomer. Only in the film state is transparent, the appearance is translucent, the appearance is cloudy or opaque, and the hardness is from soft to, which is a crystalline plastic. Generally colorless, completely transparent without additives, this type of plastic is amorphous, in general, crystalline and amorphous are thermoplastics. Thermosets are usually used with fillers and are impermeable, such as transparent when no other fillers are available. The elastomer has a rubber-like feel and a certain elongation.
2. Heating identification of greenhouse film. The heating technology characteristics of different plastic films are also different, and can be identified by heating methods at the same time. Thermoplastics are easy to soften and melt when heated, and when melted, they can pull the filament from the melt and become transparent, making it easy to heat seal. Thermosetting plastics are heated to keep their original hardness not soft, the size is relatively stable, and the decomposition temperature is carbonized before the chemical decomposition of the material. When the elastomer is heated, no flow occurs until the chemical decomposition temperature, and the material is decomposed and carbonized at the decomposition temperature.
3. Solvent treatment identification of greenhouse film. Thermoplastic engineering plastics will continue to swell in the solvent system, but generally insoluble in cold solvents, in hot solvents, some thermoplastic materials plastics will be dissolved; Thermosetting plastics are insoluble in solvents, and generally do not swell or only swell slightly; Elastomers usually swell but are insoluble in solvents.
4. Density identification of greenhouse film plastics. Different kinds of plastics have different densities. Because the density of foamed plastic is not the true density of the material, the foamed products need to be separated. In the actual industry, there are also different densities of plastics to sort plastics.
5. Pyrolysis test identification of greenhouse film plastics. Pyrolysis uses litmus test strip or pH test strip to heat plastics in pyrolysis tubes, which are identified according to the pH value of the escaping gas tested.