Environmental stress crack resistance of structural polyethylene: modelling long-term material performance

结构聚乙烯的耐环境应力开裂性：模拟长期材料性能

• 批准号: 349510-2006
• 负责人: Polak, Maria
• 金额: $ 1.7万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=365988
• 关键词: Environmental; stress; crack; resistance; structural

This proposal addresses modelling of failure of polyethylene (PE) in the context of the applicability of this material for the construction industry.  Long term performance of PE is likely the most critical issue that needs to be addressed in order to safely use PE and similar polymers as construction materials. Long term performance and failure (slow crack growth, creep rupture or yield) of PE are directly related to its environmental stress crack resistance (ESCR), which is determined in laboratory conditions. However, the relationship between ESCR and the structural performance of polyethylene in real conditions is not well understood.The proposed research will involve: 1) analysis and evaluation of ESCR testing methods in terms of the physical phenomena influencing each type of test, 2) determination of rational failure criteria based on ESCR test results and molecular structure of PE, 3) implementation of these failure criteria into macromechanical time-dependent constitutive formulations, and 4) implementation of the constitutive formulations into finite element analysis procedures. The study will be done by examining mechanics of creep, plastic deformations and failure on the molecular, micro-mechanical and macro-mechanical levels.  The relationship between micro- and macro-levels will be established.  The objectives will be realized by a comprehensive research program, which will include laboratory testing (both chemical and mechanical) as well as the development of theoretical mechanical modelling for polymeric materials.  The proposed research project is part of a larger research initiative carried out at the University of Waterloo that focuses on linking chemical and mechanical properties of polymers.  The goals are developing rational constitutive formulations, necessary for practical utilization of polymers in structures and specifying appropriate manufacturing and molding processes when the required (desired) mechanical properties are known, allowing to produce improved materials for specific applications.

本提案针对聚乙烯（PE）在建筑行业的适用性背景下的失效建模。为了安全地使用PE和类似聚合物作为建筑材料，PE的长期性能可能是需要解决的最关键问题。PE的长期性能和失效（缓慢裂纹增长、蠕变断裂或屈服）与其在实验室条件下测定的耐环境应力开裂性（ESCR）直接相关。然而，在真实的条件下，ESCR与聚乙烯结构性能之间的关系尚未得到很好的理解。拟议的研究将涉及：1）根据影响每种试验的物理现象分析和评价ESCR试验方法，2）根据ESCR试验结果和PE的分子结构确定合理的失效标准，3）将这些失效准则实施为宏观力学的时间相关本构公式，以及4）将本构公式实施为有限元分析程序。研究将从分子、微观和宏观力学水平上研究蠕变、塑性变形和破坏的力学机制。将建立微观和宏观水平之间的关系。目标将通过一个综合研究计划来实现，包括实验室测试（化学和机械）以及聚合物材料理论力学模型的开发。拟议的研究项目是在滑铁卢大学，专注于聚合物的化学和机械性能的联系，其目标是开发合理的结构配方，在结构中实际使用聚合物所必需的，并指定适当的制造和成型工艺时，所需的（所需的）机械性能是已知的，允许为特定应用生产改进的材料。