August 27, 2020
The proportion of photons in the total is very small
The proportion of photons in the total is very small, so fluorine materials
have good environmental and weather resistance. Because the stable fluorine
atoms surround the carbon chain, PVDF has good chemical stability and is not
easily corroded by acids, alkalis, strong oxidants and halogens at room
temperature. Because PVDF is soluble in some strong polar solvents and has good
spinnability, it can be used for spinning to prepare hollow fiber membranes.
It
is a polymer material with good film-forming properties, such as
dimethylformamide (DMF) and dimethylacetamide (DMAC) and N-methylpyrrolidone
(NMP) and other polar solvents dissolve.Abstract: Polyvinylidene fluoride
(PVDF) has the advantages of PTFE Coated
Fabric low price, good chemical and thermal stability, and high mechanical
strength. The serious pollution in the separation process restricts the
application of PVDF separation membranes.
The wavelength of photons is between
200-700nm, and the CF bond energy is close to 220nm. Because fluorine atoms have
large electronegativity and small atomic radius, the CF bond length is short,
and the bond energy can reach 50kJ. Polyvinylidene fluoride was first
commercialized in the construction field in 1961.. Keywords: polyvinylidene
fluoride, hydrophilicity, contact angle 1.mol- 1.
The melting point is 170°C,
the thermal decomposition temperature is above 316°C, and it will not decompose
within 2 years of continuous exposure to high temperatures below 150°C. In
recent years, fluoropolymers have been used as a kind of membrane material with
excellent performance, and their research and application in the field of
membrane separation engineering have become a hot topic. However, the
symmetrical distribution of fluorine atoms on the PVDF molecular chain results
in low surface energy and strong hydrophobicity on the surface of the material.
Due to the symmetrical distribution of fluorine atoms, the whole molecule shows
non-polarity, and the surface energy of the polymer is very low, only 25J.
Fluorine atoms replace hydrogen atoms. Introduction to PVDF[1] PVDF is obtained
by suspension polymerization or emulsion polymerization of vinylidene fluoride
monomer CH2=CF2. Therefore, the surface of the membrane material needs to be
hydrophilized and modified. The modification of polyvinylidene fluoride membrane
mainly includes two methods, physical and chemical, and then can be used to test
the contact angle and pure water flux of the membrane to characterize its
hydrophilicity and hydrophobicity.
The entire molecular chain is flexible to
make the polymer have a certain degree of crystallinity, showing outstanding
thermal stability.m-3. The excellent performance of PVDF resin has been widely
proven in the decades of use, and it has been widely used in X-ray lithography,
optical fiber, coatings, etc. From the analysis of PVDF molecular structure, the
whole conforms to the zigzag configuration of the carbon chain of general
polyolefin molecules. Generally, the visible light---ultraviolet light in solar
energy has a destructive effect on organic matter
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August 18, 2020
It has excellent chemical stability
The advantage of PFA is that it has a higher continuous use temperature of
260°C, stronger stiffness and toughness, and is suitable for anti-sticking and
chemical resistance applications under high temperature conditions. (all are the
transliterations of TEFLON). Teflon is divided into four types: PTFE, FEP, PFA, and ETFE.
Teflon
(Teflon spray) coating is a special high-performance coating (paint) that
combines heat resistance, chemical inertness, excellent insulation stability and
low friction, and has comprehensive advantages that other coatings cannot
compete. Because of the pronunciation, it is usually called Teflon, Teflon, and
Teflon.Teflon PFA: PFA (perfluoroalkyl compound) non-stick coating, like FEP,
melts and flows during baking to form a non-porous film.
Teflon FEP: FEP
(Fluorinated Ethylene Propylene Copolymer) non-stick coating melts and flows to
form a non-porous film during baking.Teflon paint (paint), the English name is
TEFLON, is a kind of fluorine paint with polytetrafluoroethylene Toaster Bag
Manufacturers as the matrix resin.
Its
flexible applicability makes it widely used in: cookware, tableware, furniture,
molds, home appliances, automobiles, machinery, medicine, technology and so on.
The maximum use temperature is 200 ℃. It has excellent chemical stability and
excellent non-stick characteristics.　　 Teflon PTFE: PTFE
(polytetrafluoroethylene) non-stick coating can be used continuously at a high
temperature of 260 ℃, the highest use temperature can reach 290-300 ℃, very low
friction coefficient, good wear resistance and excellent chemistry
stability.kytfl.html Teflon coating, Teflon coating.
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