Regarding the issue of paraformaldehyde
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Our company uses a large amount of polyformaldehyde, but the polyformaldehyde available for purchase comes in only two grades: one with a purity of around 92% and another with a purity of around 96%. Why aren’t there higher purity grades, such as 99%? What are the main impurities present in polyformaldehyde? Water?
Our company also uses a significant amount of paraformaldehyde; is there any simple way to determine its concentration?
The international standards for polyoxymethylene can be found at http://bbs.hcbbs.com/viewthread.php?tid=73679. I checked, and 99% of the product manufacturers in China use this standard; for example, Shanghai Yichen Chemical Raw Materials Co., Ltd. You can do a search on your own
We produce polyformaldehyde, with a purity of 96%; it’s possible to achieve 99% purity as well. However, the higher the purity, the higher the degree of polymerization. You can contact me by phone for more details, or I can send them to you via text message
What experimental methods are used to determine the content of paraformaldehyde?
Method principle: In the presence of a small amount of basic catalyst, solid formaldehyde is initially depolymerized in water. The determination of free methanol is carried out by separation using capillary gas chromatography, detection with a TCD detector, and quantification of the methanol content in formaldehyde via the internal standard method.
Currently, there are mainly two grades of polyformaldehyde available on the market: >92% and >96%. Is it true that the higher the polyformaldehyde content, the more difficult it is to depolymerize it? What is the composition of those 8% remaining in polyformaldehyde with a content of only 92%?
For products of the same grade, generally speaking, the higher the content, the greater the degree of polymerization, and the more difficult it is to depolymerize them. 92% is polyformaldehyde; the remaining 8% consists mainly of bound water and free water – about 5-6% – as well as around 0.5% methanol. There are also small amounts of ash and iron present. This post was last edited by Arctic Circle on 2009-3-31 17:13]
What is ash, and what is the proportion of iron ions?
For different products, the control values can be found in the manufacturer’s specification sheets. Ash content is presumably the percentage of residues remaining after burning the substance.
Does polyformaldehyde depolymerize in methanol to produce formaldehyde?