甲基纤维素对硬石膏机械性能影响的实验研究

摘要

目的:研究应用不同浓度的甲基纤维素溶液调拌硬石膏(甲基纤维素溶液的浓度分别为0.01%,0.02%,0.03%,0.04%,0.05%)对硬石膏模型抗弯强度及尺寸稳定性的影响.方法:将硬石膏材料与石膏调和液(对照组为三蒸水,实验组为5种不同浓度的甲基纤维素溶液)按标准水粉比(28ml:100g)调和,真空搅拌40s后灌制石膏模型,1 h后脱模,室温下放置72 h后分别测试各组模型的抗弯强度和尺寸.结果:应用浓度为0.02%的甲基纤维素溶液调拌后硬石膏的抗弯强度明显提高,与对照组存在统计学差异(P <0.05),其尺寸与对照组无统计学差异(P >0.05);应用浓度分别为0.01%,0.04%,0.05%的甲基纤维素溶液调拌后,硬石膏抗弯强度降低,与对照组无统计学差异(P >0.05),尺寸稳定性差异未见显著性(P >0.05);应用浓度为0.03%的甲基纤维素溶液调拌后,硬石膏的抗弯强度提高,对照组差异未见统计学(P >0.05),尺寸与对照组在颌龈方向有统计学差异(P <0.05).结论:应用浓度为0.02%的甲基纤维素溶液调拌后明显提高了硬石膏的抗弯强度,且尺寸稳定.%Objective: To study the influence of methylcellulose with different concentration on anti-bending strength and dimensional changes of dental stones.The concentration of methylcellulose is 0.01％, 0.02％, 0.03％, 0.04％, 0.05％ respectively.Methods: The dental stones were divided into two groups, the control group was mixed with distilled water and the experimental group was mixed with 5 kinds of methylcellulose solutions with different concentrations.Dental stones were made by mixing of methylcellulose with different concentration(the experiment group) or distilled water(the control group) and dental stone powder in vacuum mixer for 40s,and then were poured into the block mould, 1 hour later, the models were demolded and dry up for 72 hours naturally indoor.The bending resistance was tested and the dimensional sizes of the gypsum casts were measured.Results: When the concentration of methylcellulose was 0.02％, the bending resistance obviously exceeded the control group and showed statistic differences (P＜0.05), and the dimensional accuracy was not affected, When the concentration of methylcellulose were 0.01％, 0.04％ or 0.05％, the bending resistance was reduced, but the difference was not statistically significant(P＞0.05) and the dimensional accuracy was not affected(P＞0.05), When the concentration of methylcellulose was 0.03％, the bending resistance was increased, but no significant difference compared with the control group(P＞0.05), the dimensional accuracy was affected(P＜0.05).Conclusions: when its concentration was 0.02％ the Methylcellulose increased the bending resistance obviously and the dimensional accuracy was not affected.