Electric conductivity of wet recycled paper sheets

为了建立回收纸浆中添加剂的定量测定方法，研究了湿纸浆卷材的电导率和干纸浆卷材的傅里叶变换衰减全反射红外光谱。含聚丙烯酰胺（PAM）干强添加剂的纸张和进一步回收的纸张结束语如下：1。湿纸浆片的电导率随PAM保留量的增加而降低。PAM中阳离子含量越多，电导率越低。不含PAM的湿纸浆片在第一次回收时电导率下降，再循环后电导率变化不大。另一方面，对于含有PAM的板材，其电导率几乎不受任何回收的影响。含PAM和不含PAM的膜的ATR光谱的差异给出了膜中残留PAM的光谱。PAM表征带的吸光度随板材中PAM含量的增加而线性增加，与加热程度无关。因此，提出了一种使用FT-IR-ATR光谱的简便技术来测定PAM的保留量。此外，通过ATR棱镜和光束角度的变化，光谱变化表明，无论加热程度如何，PAM的分布都非常接近纸浆纤维表面。随着回收程序的增加，保留在纸页中的PAM逐渐被去除。PAM的去除率为10%左右。与PAM用量的减少相比，回收后的拉伸强度下降幅度较大。

In order to develope quantitative determination of additives in recycled pulp, electric conductivity of wet pulp web and Fourier transform attenuated total reflection infrared (FT-IR-ATR) spectra of dry pulp sheet were investigated in this study. The concluding remarks for the paper sheets containing polyacrylamide (PAM) dry-strength additives and those further recycled are as followed.1.The electric conductivity of wet pulp sheet decreased with an increase of the PAM amount retained. The more cation amoumt in PAM increased the more the electric conductivity decreased.2.The electric conductivity of wet pulp sheet without PAM decreased on the first recycling and hardly changed by further recycling. On the other hand for the sheet with PAM,the electric conductivity hardly changed by any recycling.3.The difference ATR spectra between those of the sheets with and without PAM gave spectra of the PAM retained in the sheets. The absorbance of PAM characterizing band linearly increased with PAM content of the sheets irrespective of beating degree. Thus, a handy technique using FT-IR-ATR spectroscopy was proposed for determing the amount of PAM retained. Further, spectrum changes through the changes of ATR prism and beam angle indicated that PAM distribution very close to the pulp fiber surfaces irrespective of beating degree.4.The PAM retained in the sheets were gradually removed with an increase of the number of recycling procedures. The ratio of PAM removing was about 10% for a recycling. The decrease of tensile strength by recycling was large comparing with the decrease of PAM amount by recycling.