By applying heat and pressure to thermoplastic materials, the overlap of the two pieces can be bonded to form hermetic systems. Polymethylmethacrylate (PMMA) is a thermoplastic used in commercial microfluidic devices; its advantages include low cost, ready fabrication, and high transparency. In order to gain an understanding of PMMA's relevant characteristics (thermal behavior, material strength, and hermetic sealing strength), we study its bulk properties and mechanical behavior. Experimental results of the cohesion behavior of PMMA sheets were collected and are presented here. Samples were bonded by subjecting a sample to elevated pressure and temperature in the glass transition range (85 degrees C-165 degrees C), which was determined beforehand by differential scanning calorimetry and literature. Five different bonding temperatures (140 degrees C, 150 degrees C, 160 degrees C, 170 degrees C, and 180 degrees C) and three bonding pressures (1.2, 1.4, and 1.6 MPa) were applied for making samples; mechanical strength tests were then carried out to understand separately the bulk mechanical strength and the interfacial properties (shear strength and bonding strength) of a cohesive laminate at the temperatures near the glass transition range. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers