Lovell L G, Lu H, Elliott J E, Stansbury J W, Bowman C N
Department of Chemical Engineering, University of Colorado, Boulder, 80309-0424, USA.
Dent Mater. 2001 Nov;17(6):504-11. doi: 10.1016/s0109-5641(01)00010-0.
This study investigates the effect of cure rate on the mechanical properties of a common dimethacrylate dental resin formulation (75/25 wt% bis-GMA/TEGDMA).
The polymerization rate and final conversion of the exact specimens subsequently used for mechanical testing were monitored by near-infrared (near-IR) spectroscopy. The glass transition temperature (T(g)) and modulus, as a function of temperature, were determined by dynamic mechanical analysis (DMA). Iniferter initiating systems were used to create partially cured networks that did not contain any trapped radicals. By the elimination of trapped radicals from the system, the formed networks can be characterized as a function of both temperature and double bond conversion without inducing additional thermal cure during testing.
Copolymer specimens were cured with UV and visible light initiating systems, UV light intensities that varied by over four orders of magnitude, and cure temperatures that differed by 60 degrees C. Even though the polymerization rates for these resins were vastly different, similar T(g) and modulus were measured for specimens cured to the same final double bond conversion.
This study shows that highly cross-linked dimethacrylate systems, such as bis-GMA/TEGDMA, exhibit similar network structure and properties as a function of double bond conversion, regardless of the method or rate of cure.
本研究调查固化率对一种常见的二甲基丙烯酸酯类牙科树脂配方（75/25重量%双酚A缩水甘油醚/三乙二醇二甲基丙烯酸酯）机械性能的影响。
随后用于机械测试的精确试样的聚合速率和最终转化率通过近红外光谱进行监测。玻璃化转变温度（T(g)）和模量作为温度的函数，通过动态力学分析（DMA）来确定。引发转移终止剂引发体系用于创建不包含任何捕获自由基的部分固化网络。通过从体系中消除捕获自由基，所形成的网络可以被表征为温度和双键转化率的函数，而在测试过程中不会引发额外的热固化。
共聚物试样用紫外光和可见光引发体系、变化超过四个数量级的紫外光强度以及相差60摄氏度的固化温度进行固化。尽管这些树脂的聚合速率差异很大，但对于固化至相同最终双键转化率的试样测量到了相似的T(g)和模量。
本研究表明，高度交联的二甲基丙烯酸酯体系，如双酚A缩水甘油醚/三乙二醇二甲基丙烯酸酯，无论固化方法或速率如何，作为双键转化率的函数都表现出相似的网络结构和性能。
