分子质量对脂肪族高效减水剂性能的影响

Effects of molecular weight on the performance of sulfonated acetone-formaldehyde superplasticizers

制备了一系列原料配比相同,分子质量不同的脂肪族高效减水剂(SAF)。采用红外光谱(FT-IR)和凝胶渗透色谱(GPC)测试了SAF的分子结构,并通过净浆流动度测试了其分散性。结果表明:不同分子质量的SAF的FT-IR谱图具有相同的特征官能团吸收峰;但是从GPC曲线可以看出,低分子质量的SAF是线性缩聚物,高分子质量的SAF包含一定量的交联缩聚物,且随分子质量的增大,交联产物占比逐渐增多;SAF的分散性随分子质量的增大,呈先增大后减小,分散保持性在分子质量15 000以内时,随着分子质量的增大基本无变化;在相对分子质量大于15 000时,随着分子质量的增大而变差。

A series of sulfonated acetone-formaldehyde superplasticizers （SAF） with same raw materials ratio and different molecular weight were synthesized. The structure of the SAF were characterized by FT-IR and GPC,and disperse performance were evaluated by cement paste fluidity test. The results showed that：SAFs with different molecular weight own same FT-IR spectrums, which means their chemical functional groupsare same. GPC indicated that low molecular weight SAF are linear structures polycon- densate,but SAF with high molecular weight consist of linear and crosslinked products,moreover, the amount of the crosslinked prod- ucts increase with the increase of molecular weight. The disperse performance of SAF first increase then decrease with the increase of molecular weight,the disperse retention performance of SAF hardly had changed when the relative molecular weight is under 15000, however, the disperse retention performance became worse when the molecular weight is over 15000.