SBIR Phase II: Smart Two-Way Shape Memory Polymer Based Sealant

该小型企业创新研究第二阶段项目旨在提供一种经济实惠的密封剂，用于密封水泥混凝土路面，沥青混凝土路面，桥面等的接缝和裂缝。在交通基础设施中，接缝是故意建造的，以便在温度上升/下降时，由于线性热膨胀/收缩而使结构元件移动。裂缝是路面中常见的失效模式，如果没有适当密封，可能导致混凝土的水损害和破裂。密封裂缝和接缝是保持或延长结构元件使用寿命的常见做法。目前使用的各种密封剂的年市场价值约为61亿美元。不幸的是，这些密封剂中的许多不能正常工作，并且在延长使用寿命方面无效。在这个项目中，将开发一种智能密封剂，它在冷却时膨胀，在加热时收缩，这是一种与混凝土相反的热特性。该产品将解决该行业中由连接/开裂结构元件的热运动引起的重大问题。预计该产品将在5年内拥有约0.8%的市场份额，以满足更持久和更可靠的基础设施的需求。该项目的智力价值在于智能密封剂技术的开发和验证。接缝失效的根本原因是大多数密封剂的热膨胀特性与混凝土相似，即，冷却时收缩，加热时膨胀。这种行为与为了避免密封剂和混凝土之间的热致分离而对密封剂的要求相反。不幸的是，很少有材料可以以成本有效的方式满足这一要求，同时保持其他所需的物理性能（如变形性）。该二期项目将通过使用基于双向形状记忆聚合物（2 W-SMP）的密封剂来解决这个长达一个世纪的问题，从而解决根本原因。二期工程将在一期工程可行性研究的基础上，进一步完善2 W-SMP基路面接缝或裂缝密封胶，并通过第三方实验室规模测试和湿热环境及极寒地区的全尺寸现场验证来验证产品。技术成果将包括实验室规模的验证、现场性能和验证，以及这种新型智能材料的施工协议，为业主和运输机构的采用奠定坚实的基础。

This Small Business Innovation Research Phase II project aims to provide an affordable sealant for sealing joints and cracks in cement concrete pavement, asphalt concrete pavement, bridge deck, etc. In transportation infrastructure, joints are intentionally constructed in order to allow movement of the structural elements due to linear thermal expansion/contraction when temperature rises/drops. Cracks are a common failure mode in pavement, and if not properly sealed, can cause water damage and rupture of the concrete. Sealing cracks and joints is a common practice to maintain or extend the service life of structural elements. Various types of sealants are currently used with an annual market value of about $6.1 billion. Unfortunately, many of these sealants fail to work properly and are ineffective in extending service life. In this project, a smart sealant will be developed that expands upon cooling and contracts upon heating, a thermal characteristic opposite to that of concrete. The product will address a significant problem in the industry arising from thermal movement of joined/cracked structural elements. It is expected that the product will have about 0.8% market share in 5 years helping with the need for longer lasting and more reliable infrastructure.The intellectual merit of this project lies in the development and validation of a smart sealant technology. The root cause for joint failure is that the thermal expansion characteristics of most sealants is similar to that of concrete, i.e., contraction upon cooling and expansion upon heating. This behavior is contrary to what is required of sealants in order to avoid thermally induced separation between the sealant and the concrete. Unfortunately, few materials can fulfill this requirement in a cost effective way while maintaining other desired physical properties (such as, deformability). This Phase II project will solve the century-long problem through the use of a two-way shape memory polymer (2W-SMP) based sealant that addresses the root cause. Building upon the feasibility study of the Phase I project, the Phase II project will focus on further improving the 2W-SMP based sealant for sealing joints or cracks in pavement, and validate the product through third-party lab-scale testing, and full-scale field-level verification in both hot and humid environment and extremely cold regions. Technical outcome will include lab-scale validation, field level performance and verification, and construction protocols for this new smart material, laying a solid foundation for adoption by home owners and transportation agencies.