Mechanical properties and microstructural characterization of semi-crystalline polymers and fiber composites

半结晶聚合物和纤维复合材料的机械性能和微观结构表征

• 批准号: RGPIN-2022-03588
• 负责人: Jar, PeanYue
• 金额: $ 2.33万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760193
• 关键词: Mechanical; properties; microstructural; characterization; semi

The proposed study is concerned about mechanical performance of semi-crystalline polymers (SCP) and fiber composites (FRP) of which the microstructure consists of two phases, i.e. amorphous and crystalline phases in SCP and fiber and polymer matrix in FRP. Interaction between the two phases is known to start at small deformation. With a strong viscous behavior and low resistance to damage development, the dominant mechanisms for deformation of SCP and FRP vary with the loading history. As a result, conventional test methods cannot provide full characterization of mechanical performance of these materials in service.    The long-term goal of the proposed study is to develop a mechanism-based concept to define mechanical properties for SCP and FRP so that the lab test results can be used to evaluate mechanical performance in the long-term service. Study in the next five years has two specific objectives. The first is to develop two new test methods, one for SCP and the other for FRP, to separate mechanical properties associated with the viscous deformation from those with the quasi-static counterpart, and to use changes of the mechanical properties to quantify their resistance to damage. The other objective is to examine microstructural changes of SCP and FRP to identify mechanisms that dominate the deformation process, and to determine the critical conditions for the mechanism changes. Dominant mechanisms in three fundamental loading modes of tension, compression and shear will be considered. By correlating the mechanical properties obtained from the new test methods with mechanisms established from the microstructural changes, the proposed study will provide a foundation for developing a mechanism-based concept to characterize mechanical properties for SCP and FRP, and to evaluate efficacy of this concept for quantifying the load-carrying performance of these materials.    The study will provide training to two PhD and two MSc students, plus one undergraduate student in each summer. Currently, one PhD student is developing a new test method for SCP, and has made significant progress in separating the viscous stress component from the quasi-static counterpart to establish the corresponding stiffness change and damage development during the test. An MSc student will be recruited to use this new test method to examine two SCPs with their amorphous phases in different states (rubbery or glassy), and to characterize their influence on the crystalline microstructure under loading. The second PhD student will develop a new test method for FRP and to characterize the void generation in the matrix and critical conditions for its evolution to cause delamination. The second MSc student will study the influence of a combined loading mode of tension and compression on the mechanical property changes for each of the two phases in SCP, to evaluate the feasibility of quantifying the damage development when subjected to a combination of different loading modes.

拟议的研究关注半结晶聚合物（SCP）和纤维复合材料（FRP）的机械性能，其微观结构由两相组成，即SCP中的非晶相和结晶相以及FRP中的纤维和聚合物基体。已知两相之间的相互作用从小变形开始。 SCP 和 FRP 具有较强的粘性行为和较低的抗损伤发展能力，其变形的主要机制随加载历史的变化而变化。因此，传统的测试方法无法提供这些材料在使用中的机械性能的完整表征。    该研究的长期目标是开发一种基于机制的概念来定义 SCP 和 FRP 的机械性能，以便实验室测试结果可用于评估长期使用中的机械性能。未来五年的研究有两个具体目标。第一个是开发两种新的测试方法，一种用于 SCP，另一种用于 FRP，将与粘性变形相关的机械性能与准静态对应物的机械性能分开，并利用机械性能的变化来量化其抗损坏能力。另一个目标是检查 SCP 和 FRP 的微观结构变化，以确定主导变形过程的机制，并确定机制变化的关键条件。将考虑拉伸、压缩和剪切三种基本载荷模式的主要机制。通过将新测试方法获得的机械性能与微观结构变化建立的机制相关联，拟议的研究将为开发基于机制的概念奠定基础，以表征 SCP 和 FRP 的机械性能，并评估该概念在量化这些材料的承载性能方面的功效。    该研究将在每年夏天为两名博士生和两名硕士生以及一名本科生提供培训。目前，一名博士生正在开发一种新的 SCP 测试方法，并在将粘性应力分量与准静态对应部分分离以建立测试过程中相应的刚度变化和损伤发展方面取得了重大进展。将招募一名理学硕士学生使用这种新的测试方法来检查两种具有不同状态（橡胶状或玻璃状）非晶相的 SCP，并表征它们在负载下对晶体微观结构的影响。第二名博士生将开发一种新的 FRP 测试方法，并表征基体中空隙的产生及其演变导致分层的关键条件。第二名理学硕士学生将研究拉伸和压缩的组合加载模式对 SCP 两个阶段机械性能变化的影响，以评估在不同加载模式组合时量化损伤发展的可行性。