Van der Voort Maarschalk K, Zuurman K, Van Steenbergen M J, Hennink W E, Vromans H, Bolhuis G K, Lerk C F
Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, The Netherlands.
Pharm Res. 1997 Apr;14(4):415-9. doi: 10.1023/a:1012078928297.
The purpose of this study was to relate the combination of glass transition temperature (Tg) and temperature of measurement with the mechanical and compaction properties of some test materials.
Copolymers with different Tg'S were synthesised by free radical copolymerisation of methyl methacrylate with lauryl methacrylate. Elastic moduli were measured by dynamic mechanical analysis at different strain rates and temperatures. Compaction experiments were performed at different compaction speeds and temperatures.
The difference between temperature of measurement and Tg appears to determine both elastic modulus and yield strength completely. They both decrease with decreasing difference between temperature of measurement and Tg and increase with strain rate. At temperatures of measurement higher than the Tg the elastic modulus is extremely low because the materials behave as rubbers. Consequently, the amount of energy stored during compaction decreases when the compaction temperature approaches the Tg and increases with strain rate. When the compaction temperature is higher than the Tg, the amount of stored energy is extremely large. The compaction experiments show that the final tablet porosity is completely determined by stress relaxation phenomena. Consequently, the final tablet porosity follows exactly the same relation as that of stored energy.
The final tablet porosity is unequivocally determined by the amount of stored energy. This implies that tablet production at a temperature of about 20 K under the glass transition temperature of the material yields tablets with minimum porosity.
本研究的目的是将玻璃化转变温度（Tg）与测量温度的组合与某些测试材料的机械性能和压实性能联系起来。
通过甲基丙烯酸甲酯与月桂基甲基丙烯酸酯的自由基共聚合成具有不同Tg的共聚物。通过动态力学分析在不同应变率和温度下测量弹性模量。在不同压实速度和温度下进行压实实验。
测量温度与Tg之间的差异似乎完全决定了弹性模量和屈服强度。它们都随着测量温度与Tg之间差异的减小而降低，并随着应变率的增加而增加。在高于Tg的测量温度下，弹性模量极低，因为材料表现为橡胶。因此，当压实温度接近Tg时，压实过程中储存的能量减少，并随应变率增加。当压实温度高于Tg时，储存的能量非常大。压实实验表明，最终片剂孔隙率完全由应力松弛现象决定。因此，最终片剂孔隙率与储存能量的关系完全相同。
最终片剂孔隙率明确地由储存能量的量决定。这意味着在材料玻璃化转变温度以下约20K的温度下生产片剂会得到孔隙率最小的片剂。
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