GOALI: Novel Flame Retardant Phenolic-Epoxy Resins Processable via Rapid Fabrication Methods

聚合物基复合材料是钢铁和混凝土的潜在替代品，用于民用和工业结构，如隧道、公共交通设施、桥梁、化学和加工厂设施、海上石油钻井平台等，这些主要需要轻质和长期耐腐蚀性。然而，限制有机材料在公共建筑中使用的一个主要障碍是它们的易燃性。目前还没有一种聚合物基体能够满足不可燃性、韧性和强度好、可加工成连续纤维增强复合材料的综合要求，这种复合材料可以通过低成本、快速的方法（如拉挤或压力注塑）制成，而且材料成本低。酚醛树脂是一种体积大、用途广泛的材料，包括结构粘合剂、复合材料、涂料等。众所周知，它们在许多应用中具有耐火性能。初步研究表明，选择高官能团的酚醛低聚物与化学计量量不足的二氧化物反应，可以通过快速连续的过程将前驱体加工成复合材料，产生无空隙、相对坚韧、阻燃、坚韧的酚醛-环氧热固性材料，并研究其复合材料的化学结构与火焰性能之间的关系。该研究将由弗吉尼亚理工大学和陶氏化学公司的研究人员共同进行。具体特点包括：(1)开发新型环氧交联试剂（含磷氧化物和聚硅氧烷），以提高阻燃性，而不使用卤化芳烃（导致有毒烟雾的产生）；(2)研究生成具有选择性端基反应活性的可控新聚物，用于制备具有少量环氧组分的坚韧、无空隙的酚醛-环氧网络；(3)开发潜在亲核催化剂，为连续加工操作定制固化动力学，特别是拉挤和快速压力注射；(4)对化学结构和网络结构、机械性能和阻燃性之间的关系进行基础研究；(5)生成连续纤维增强复合材料，研究树脂性能和复合材料性能之间的关系。包括暴露于受控燃烧后的残余强度测量，以评估损伤进展动力学。低成本、不易燃的聚合物复合材料可以满足建筑、运输和其他建筑项目中对结构部件的关键需求，这些建筑项目的密闭空间在发生火灾时无法快速疏散。这种方法也可以用于预制组件，以提高现场施工效率。在海上石油平台、海军上层结构和潜艇、矿井和公共交通设施中存在着特别的需求，这些设施的轻质和可靠的结构性能是必不可少的。本研究解决了轻质阻燃材料的发展和基本认识，将其纳入结构复合材料，以及它们在火灾中的性能。

9903672RifflePolymer matrix composites are potential alternatives to steel and concrete for civil and industrial structures such as tunnels, mass transit facilities, bridges, chemical and processing plant facilities, off-shore oil drilling rigs, etc. where light weight and long term corrosion resistance are major needs. One major obstacle, however, limiting the use of organic materials in public structures is their flammability. There are currently no polymer matrix candidates which meet the combined requirements of non-flammability, good toughness and strength, processability into continuous fiber reinforced composites by cost effective, rapid methods such as pultrusion or pressure injection molding, and low materials' costs. Phenolic resins are high volume materials widely utilized for many purposes, including structural adhesives, composites, coatings, etc. They are also well known to provide fire resistance in many applications. Pilot studies have demonstrated that the reaction of selected high functionality phenolic novolac oligomers with a stoichiometrically deficient amount of a diepoxide can produce void free, relatively tough, flame retardant, tough, phenolic-epoxy thermosets from precursors processable into composites by rapid continuous processes, and to investigate the relationships between chemical structure and flame performance of their composites. The research will be conducted jointly between researchers at Virginia Tech and the Dow Chemical Co. Particular features include: (1) Development of new epoxy crosslinking reagents containing phoshpine oxides and polysiloxanes for improved fire resistance without the use of halogenated aromatics (which lead to toxic smoke generation), (2) A study of the generation of controlled novolac oligomers with selective endgroup reactivity for preparing tough, void-free, phenolic-epoxy networks with minor amounts of the epoxy components, (3) Development of latent nucleophilic catalysts to tailor curing kinetics for continuous processing operations, notably pultrusion and rapid pressure injection, (4) A fundamental study of the relationships between chemical and network structure, and mechanical properties and flame resistance, and (5) The generation of continuous fiber reinforced composites to study relationships between resin properties and composite properties, including residual strength measurements after exposure to controlled burning to evaluated damage progression kinetics.Cost effective, non-flammable polymer composites could fill a critical need for structural components in buildings, transportation, and other construction projects where confined spaces make rapid evacuation in case of fire impossible. This approach could also be used to pre-fabricate components for efficient on-site construction. Particular needs exist in off-shore oil platforms, navy topside structures and submarines, mine shafts, and mass transit facilities where both lightweight and reliable structural performance are essential. This research addresses the development and fundamental understanding of lightweight, flame retardant materials, their incorporation into structural composites, and their performance in a fire.