多尺度界面结构玻璃–PMMA层合透明材料制备、力学行为及可靠性研究

The transparent composites of glass/PMMA laminates, consisting of glass and polymethyl methacrylate (PMMA) with the adhesive layer, exhibit superior properties such as light-weight, high strength and impact resistance. These composites show widespread applications in the aviation, vehicles and construction fields. Owing to the mismatch of thermal expansion coefficient between glass and PMMA, the stress value of glass-adhesive interface was large enough to evoke the adhesive layer delamination, leading to the low reliability of glass/PMMA laminates. This application is based on the design of multiscale interface structure. On the microscale, periodic microstructures would be fabricated on the glass surface by using the micro-indentation and wet etching process, leading to the increase of contact area and adhesive strength at the interface of glass/adhesive layer. On the macroscale, a composite coating of polyurethane-SiO2 is used as the adhesive layer, and a PMMA-PU composite coating is introduced as the transition layer, to establish the diminishing gradient of elastic modulus in the PMMA/transition layer/adhesive layer configuration. In this case, the interlaminar stress transfer could be improved, and the absorption of strain energy enhanced, resulting in the reliability promotion of transparent laminates. The influence of interface structure would be systematically investigated on the interfacial adhesion strength, interfacial fracture toughness and impact strength as well as hygrothermal and fatigue properties. These researches are intended to clarify the effects of multiscale interface structure and the related microscopic mechanisms, and thus to derive the mechanical criterion of interface failure. Combined with the reliability analysis with the Weibull theory of fracture strength, we hope to develop the organic-inorganic transparent laminates with light-weight, high reliability and longevity.

玻璃－PMMA层合透明材料是玻璃与有机玻璃（PMMA）通过胶层粘接的轻质、高强度、抗冲击复合透明材料，可广泛应用于航空、车辆、建筑等领域。由于玻璃与PMMA热膨胀系数失配，玻璃/胶层界面应力高，易脱胶失效导致可靠性较低。本申请基于多尺度界面结构设计，微观尺度上，采用微压痕-湿刻蚀技术，在玻璃表面加工周期性微结构，提高玻璃/胶层界面接触面积和粘接强度；宏观尺度上，以聚氨酯(PU)-SiO2复合涂层作为胶层，并引入PMMA-PU复合涂层作为过渡层，构建PMMA/过渡层/胶层弹性模量递减梯度，改善层间应力传递，增加应变能吸收，提升层合透明材料可靠性。系统研究界面结构对界面粘接强度、界面断裂韧度、冲击强度以及湿热老化性能和疲劳性能的影响规律；探索多尺度界面结构的力学效应及其微观机理；建立界面失效力学判据；结合断裂强度Weibull理论可靠性分析，研制轻质、高可靠性、长寿命有机－无机层合透明材料。

有机-无机层合玻璃中玻璃与有机透明材料热膨胀系数失配，粘接界面产生较高的界面应力，服役工况下胶层往复疲劳变形，导致界面脱胶失效，影响层合玻璃的使用寿命和可靠性。本项目基于多尺度界面结构设计，系统研究玻璃表面周期性微结构以及表面改性对界面剪切强度和可靠性的影响；研究梯度胶层对层合玻璃性能的影响及其作用机制；研究不同胶层层合玻璃的湿热老化性能及其界面失效的微观机理。.玻璃表面的周期性微结构显著提高玻璃/胶层界面粘接面积，改变界面应力分布，提高界面粘接性能和可靠性，界面剪切强度由7.3 MPa增加到12.9 MPa，胶层/有机玻璃界面Weibull模量由26.6增至34.4。玻璃表面KH560改性、有机材料低温等离子体改性、PU胶层有机硅改性等都有助于提高界面剪切强度，表明表面改性时界面形成化学键合。.对于PU-PMMA梯度胶层，当PU和PMMA质量比为8:2，PU预聚时间为18 h时，梯度胶层形成连续组分梯度的互穿网络结构，梯度胶层层合玻璃界面剪切强度和冲击强度达到最大值，分别为7.5 MPa和14.9 kJ/m2，后者远高于纯PU胶层层合玻璃（5.5 kJ/m2）。结合PU侧有机硅改性，冲击强度增至18.0 kJ/m2，因此，梯度胶层大幅度提升层合玻璃的抗冲击性能。.层合玻璃湿热老化试验表明，随着湿热时间延长，层合玻璃透明度先增大（<10 d）后减小，界面剪切强度快速降低，并逐渐趋于稳定值（4.5-5.5 MPa）。水分子扩散聚集以及PU水解反应弱化了界面，促进界面气泡形成与生长，导致界面脱胶失效。有限元分析表明，玻璃表面多孔二氧化硅膜层有利于提高界面失效应力，厚度超过3.8 μm时，界面失效应力基本不变，此时SiO2/PU界面最大应力快速降低。多尺度界面结构提升界面粘接性能、冲击性能及可靠性，为研制高性能有机-无机层合玻璃奠定坚实的理论基础。.