Laboratory of Chemistry and Physics of High Polymers, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
Dent Mater. 2009 Dec;25(12):1576-84. doi: 10.1016/j.dental.2009.08.001. Epub 2009 Sep 10.
The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other.
Different light-curing protocols were used in order to investigate the influence of energy density (ED), power density (PD), and mode of cure on the properties. The modes of cure were continuous, pulse-delay, and stepped irradiation. DC was measured by Raman micro-spectroscopy. C was determined by pycnometry and a density column. E was measured by a dynamic mechanical analyzer (DMA), and T(g) was measured by differential scanning calorimetry (DSC). Data were submitted to two- and three-way ANOVA, and linear regression analyses.
ED, PD, and mode of cure influenced DC, C, E, and T(g) of the polymer. A significant positive correlation was found between ED and DC (r=0.58), ED and E (r=0.51), and ED and T(g) (r=0.44). Taken together, ED and PD were significantly related to DC and E. The regression coefficient was positive for ED and negative for PD. Significant positive correlations were detected between DC and C (r=0.54), DC and E (r=0.61), and DC and T(g) (r=0.53). Comparisons between continuous and pulse-delay modes of cure showed significant influence of mode of cure: pulse-delay curing resulted in decreased DC, decreased C, and decreased T(g). Influence of mode of cure, when comparing continuous and step modes of cure, was more ambiguous.
A complex relationship exists between curing protocol, microstructure of the resin and the investigated properties. The overall performance of a composite is thus indirectly affected by the curing protocol adopted, and the desired reduction of C may be in fact a consequence of the decrease in DC.
本研究旨在探讨光固化方案对模型聚合物的转化率（DC）、体积收缩（C）、弹性模量（E）和玻璃化转变温度（T(g)）的影响，并进一步探讨这些测量值之间的相关性。
采用不同的光固化方案，研究了能量密度（ED）、功率密度（PD）和固化模式对性能的影响。固化模式为连续、脉冲延迟和分步照射。通过拉曼微光谱法测量 DC。通过比重瓶法和密度柱法测定 C。通过动态力学分析仪（DMA）测量 E，通过差示扫描量热法（DSC）测量 T(g)。数据进行了双因素和三因素方差分析及线性回归分析。
ED、PD 和固化模式均影响聚合物的 DC、C、E 和 T(g)。ED 与 DC（r=0.58）、ED 与 E（r=0.51）和 ED 与 T(g)（r=0.44）之间存在显著正相关。综合来看，ED 和 PD 与 DC 和 E 显著相关，回归系数对 ED 为正，对 PD 为负。DC 与 C（r=0.54）、DC 与 E（r=0.61）和 DC 与 T(g)（r=0.53）之间均存在显著正相关。连续和脉冲延迟固化模式之间的比较表明，固化模式具有显著影响：脉冲延迟固化导致 DC、C 和 T(g)降低。当比较连续和分步固化模式时，固化模式的影响更为模糊。
固化方案、树脂的微观结构和所研究的性能之间存在复杂的关系。复合材料的整体性能因此受到所采用的固化方案的间接影响，而 C 的降低可能实际上是 DC 降低的结果。
