The geomembrane is made of a plastic film as an impervious substrate and a geotechnical impermeable material made of a non-woven fabric. The anti-seepage performance of the new material geomembrane mainly depends on the impermeability of the plastic film. At present, the plastic film for impervious application at home and abroad mainly includes polyvinyl chloride (PVC), polyethylene (PE), and EVA (ethylene/vinyl acetate copolymer), and there are also ECB (ethylene vinyl acetate) modified in tunnel applications. Asphalt blend geomembrane, they are a kind of polymer chemical flexible material, with small specific gravity, strong extensibility, high adaptability to deformation, corrosion resistance, low temperature resistance and good frost resistance.

In view of the fact that some synthetic geomembrane field observations have certain anti-aging capabilities in engineering applications, some countries have made certain provisions for their service life in some documents, such as the former Soviet Union BCH07-74 "Earth-rock dam applications. Polyethylene impervious structure instructions, the provisions of polyethylene geomembrane can be used in buildings with a life of not more than 50 years. The conclusion in the article “Long-term properties of polypropylene composite geomembranous geosynthetics” published by Linz, Austria, states: 'The experience of field application of polypropylene for more than 15 years shows that they have high chemical and biological stability; fabrics The greatest damage is in construction; there are no major changes after laying; ... stability over 100 years can be expected.

Zinc Selenide Bi-convex Lenses

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Our company can produce many kinds of flat convex Spherical Mirrors with different sizes, radii and base materials, flat convex spherical Mirrors, flat concave spherical mirrors, double convex spherical mirrors, double concave spherical mirrors, meniscus spherical mirrors and other ordinary spherical mirrors. Special spherical mirror can also be processed, such as: achromatic spherical mirror, aspheric surface and spherical mirror group.
Materials: optical glasses such as flint glass, ultraviolet fused quartz and infrared fused quartz, as well as optical crystal materials such as calcium fluoride (CaF2), germanium (Ge), Zinc selenide (ZnSe) and silicon (Si)
Focal length: ±5mm -- ±1000mm±1%
(Germany TIROPTICS OPTOMATIC2000 test)
Outer circle: 4mm -- 200mm±0.1mm
Center thickness tolerance: ±0.1mm
Center deviation: 3-5 points
Surface accuracy: /2@
Surface quality: 40/20
Effective diameter: 90%
Plating film: according to customer requirements can be coated
In addition, we have more than a thousand kinds of standard products, and some of the standard products in stock to meet your needs

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Gold Dragon Optics Electronic Technology CO.,Ltd , https://www.golddragon-optics.com