久久99久久99精品中文字幕,国产欧美久久久精品二区仙踪林,日韩一级完整毛片,三级视频在线观看,国产精品久久人人做人人爽,一区二区三区伦理电影,av黄色在线免费观看

The polycondensation reaction refers to a polymerization reaction in which monomers react with each other to generate high molecular compounds and small molecules. Phenolic resin is formed by polycondensation of phenol and formaldehyde under catalytic conditions. According to the process characteristics of polycondensation reaction, Zhengwei Mechanical Experimental Kettle designs and manufactures reaction devices suitable for such materials.