Flexural strengths of pristine poly

<br>表1显示了填充有纳米CaCO3的原始聚酯和未饱和聚酯的抗弯强度。纯不饱和聚酯的抗弯强度为98 MPa。UPR的抗弯强度<br>填充有纳米CaCO3颗粒的颗粒连续增加至5 wt％（107 MPa），并且进一步添加纳米CaCO3颗粒会降低强度。具有7 wt％的纳米CaCO3的UPR的抗弯强度为105 MPa。在这种情况下，颗粒在基质中的分布是要考虑的重要因素。颗粒周围的应力分布会增加正在传播的裂纹的应力集中，进而引起相对较早的破坏。在较高的填料含量下可以明显看出这一点。对于较高的填料含量（> 5 wt％），附聚的机会更多，这会在颗粒附近引起高应力集中区。这个因素证明了粒子分布的重要性。纳米颗粒增强了与基质的接触表面积，从而增强了从基体到填料的应力转移，从而提高了强度。由于其微米级的填充和较高的应力集中而导致的不良界面性能为减少从基体到填充物的载荷转移铺平了道路。

原始聚酯和充满纳米 CaCO3 的不饱和聚酯的弹性强度显示在<br>表1。纯不饱和聚酯表现出 98 MPa 的柔韧强度。UPR 的柔韧性强度<br>充满纳米-CaCO3粒子的颗粒持续增加高达5wt%（107 MPa），进一步加入纳米CaCO3粒子会降低强度。UPR 与 7 wt% 纳米 CaCO3 显示 105 MPa 的柔韧强度。矩阵中粒子的分布是本案中需要考虑的一个重要因素。粒子周围的应力分布会增加传播裂纹的应力浓度，进而诱发相对早期的故障。这在填充物含量较高时可见一斑。对于较高的填充物含量（>5 wt%），聚集的机会更大，从而诱发粒子附近的高应力集中区。这一因素表明粒子分布的重要性。纳米粒子增强增强接触表面积到基质，从而增强应力从矩阵转移到填充物，从而提高强度。由于其微缩填充和高应力浓度，其不利的内部属性为从矩阵到填料的负载转移更少铺平了道路。

Flexural strengths of pristine polyester and unsaturated polyester filled with nano-CaCO3 are shown inTable 1. Pure unsaturated polyester shows a flexural strength of 98 MPa. The flexural strength of the UPRfilled with nano-CaCO3 particles increases continuously up to 5 wt% (107 MPa) and further addition of nanoCaCO3 particles decreases the strength. UPR with 7 wt% nano-CaCO3 shows a flexural strength of 105 MPa. The distribution of the particle in the matrix is an important factor to be considered in this case. The stress distributions around the particles increase the stress concentration of the propagating crack, which in turn induces relatively early failure. This is considerably seen at the higher filler content. For higher filler content (>5 wt%), the chance for agglomeration is more, which induces high stress concentrated zone near the particles. This factor demonstrates the importance of the particle distribution. The nanoparticle reinforcement enhances the contact surface area to the matrix, thereby enhancing the stress transfer from matrix to filler, which results in improved strength. The poor interfacial property owing to their micronscale filling and high stress concentration paved the way for less load transfer from the matrix to the filler.<br>