近红外光谱法测定聚乙烯醇的醇解度

Determination of alcoholysis degree of polyvinyl alcohol by near-infrared spectroscopy

建立了一种基于近红外光谱法测定聚乙烯醇(PVA)醇解度的方法,首先采用核磁共振法对37个PVA试样的醇解度进行测试,然后选取其中29个PVA试样作为校正样品集,选取合适的波长区间和最佳主因子数,先后用二阶导数和标准正则变换对各个试样的近红外光谱进行处理,并采用偏最小二乘法(PLS)建立定量分析模型,模型性能采用留一法交叉验证进行评价;剩余的8个PVA试样作为验证样品集,比较分别采用核磁共振法与近红外光谱法测试所得醇解度的差异。结果表明:基于近红外光谱法的PVA醇解度测试方法建模样本数低、操作简单、实验效率较高,醇解度的检测范围较宽(72%~99%),准确度较高,相对偏差最高仅为0.56%,且具有较高的精密度,相对标准偏差最高仅为0.07%;该方法可较好地满足高端PVA产品的开发与质控要求,具有极好的应用前景。

A method based on near-infrared spectroscopy was developed to determine the alcoholysis degree of polyvinyl alcohol(PVA).Firstly,nuclear magnetic resonance was used to test the alcoholysis degree of 37 PVA samples.29 PVA samples were selected as the calibration sample set and their near-infrared spectra were subsequently processed by second derivatives and standard normal variate transformations in appropriate wavelength ranges and optimal principal factor numbers;and a quantitative analysis model was established using partial least squares(PLS)and the model performance was evaluated by leave-one-out cross validation method.The remaining 8 PVA samples were used as validation sample sets to compare the differences in alcoholysis degree obtained by nuclear magnetic resonance and near-infrared spectroscopy.The results showed that the PVA alcoholysis degree testing method based on near-infrared spectroscopy had low modeling sample size,simple operation,high experimental efficiency,a wide detection range of alcoholysis degree(72%-99%),high accuracy,a maximum relative deviation of only 0.56%and it also exhibited high precision,with a maximum relative standard deviation of only 0.07%,which can well meet the development and quality control requirements of high-end PVA products,so it would have promising application prospects.