THERMALLY INDUCED CHANGES IN DENTAL RESIN COMPOSITES

这项研究的总体目标是提高 复合树脂作为后路修复体材料。具体地说，这 这一目标是通过系统研究聚合物的交叉效应来实现的。 连接受控成分的模型修复树脂系统。通过 控制交联链密度，有可能操纵物理 此外，我们还可以根据不同的性能和特定应用来设计聚合物。四个具体的 目的是为了验证这些假设：1.开发一个线性的 聚合物模型用于交联度的测定。这 初步步骤将使用非常相似的单功能分子 用双官能团分子BIS-GMA和TEGDMA制备均聚物 和混合(80/20、70/30和50/50wt/wt)。玻璃化转变(Tg)将 由动态机械分析(DMA)和差分确定 对这些线性体系进行了扫描量热分析(DSC)。两国关系 Tg与表面物理性能之间的硬度、弹性 模数和断裂韧性将被研究。2.开发模型 用树脂体系研究BIS-GM和TEGDMA的交联性 产生的化学和物理性质。使用单一功能的 用于特定目标#1的BIS-GMA单体，共单体将由 BIS-GMA和TEGDMA的重量比分别为80/20、70/30和50/50 将开发测试来区分交叉连接的程度 在各种配方中。Tg值与单体的比较 将线性系统转换为交联型模型。一个 固化后残留的可萃取单体的测量将被关联 具有交联链密度。对物理性能影响的比较 (硬度、弹性模数和断裂韧性)的变化 密度将被制造出来。3.确定交联度 存在于BIS-GMA和TEGDMA的模型树脂体系中。共聚单体共混物 只使用这两个分子的比例将类似于 前两个具体目标。交联剂测定结果的比较 密度、单体转化率、玻璃化转变温度、硬度、 弹性模数和断裂韧度将与模型的模数一致。 系统在具体目标2。4。确定影响交叉的因素。 链接以及这些因素对物理特性的影响。这个 以下因素将不同地研究它们对交联度的影响 密度和合成的化学和物理性质：主要单体 类型；单体/共聚单体比例；硫化方法(热固化或光固化)；水平 热固化(高或低)；光固化处理(仅光固化 或光固化加成本固化加热，具有或不具有热致自由 自由基产生剂)；以及浓度对自由基的影响 发电机。化学性质评价将由交叉链接组成 密度、玻璃化温度和单体转化率。实物资产评估将 由硬度和断裂韧性组成。不同之处的相关性 测试变量将对不同的化学和物理测试进行 确定配方和固化方式对这些参数的影响。

The overall goal of this research is to improve the performance of composite resins as posterior restorative materials. Specifically, this goal is addressed by the systematic study of the effects of polymer cross- linking upon model restorative resin systems of controlled composition. By controlling cross-link density, it may be possible to manipulate physical properties and to design polymers for specific applications. Four specific aims are directed toward testing these hypotheses: 1. to develop a linear polymer model for the determination of cross-link determination. This preliminary step will use mono-functional molecules that are very similar to the difunctional molecules of BIS-GMA and TEGDMA to make homopolymers and blends (80/20, 70/30, and 50/50 wt/wt). The glass transition (Tg) will be determined by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) for these linear systems. The relationship between Tg and the physical properties of surface hardness, elastic modulus, and fracture toughness will be studied. 2. to develop a model resin system to study the cross-linking potential of BIS-GM and TEGDMA and the resultant chemical and physical properties. Using the monofunctional monomer of BIS-GMA used in Specific Aim #1, co-monomers will be made of BIS-GMA and also of TEGDMA in ratios of 80/20, 70/30, and 50/50 wt/wt. A test will be developed to distinguish between the extent of cross-linking among the various formulations. A comparison of Tg values and monomer conversion of the linear system to the cross-linked model will be made. A measure of the extractable monomer remaining after cure will be correlated with cross-link density. Comparison of the effects on physical properties (hardness, elastic modulus, and fracture toughness) of changing cross-link density will be made. 3. to determine the extent of cross-linking occurring in model resin systems of BIS-GMA and TEGDMA. Co-monomer blends using only these two molecules will be made in ratios similar to those in the first two Specific Aims. Comparison of the results of cross-link density, monomer conversion, glass transition temperature, hardness, elastic modulus, and fracture toughness, will be made to those of the model system in Specific Aim #2. 4. to determine the factors affecting cross- linking and the impact that these factors have on physical properties. The following factors will be varied to study their influence on cross-link density and the resultant chemical and physical properties: main monomer type; monomer/co-monomer ratio; curing method (heat or light-cured); level of heat cure (high or low); treatment with light-curing (light-cured only or light-cured plus cost-cure heated with or without a heat-induced free radical generator); and the effect of concentration on free radical generator. Chemical property evaluation will consist of cross-link density, Tg, and monomer conversion. Physical property evaluation will consist of hardness, and fracture toughness. Correlation of the different test variables will be made to the different chemical and physical tests to determine the influence of formulation and cure mode on these parameters.