Synthesis and characterization of novel high temperature structural adhesives based on nadic end capped MDA-BTDA-ODA copolyimide

Abstract

A series of novel copolyimide structural adhesives were synthesized using 4,4′-diaminodiphenylmethane (MDA), 3,4′-oxydianiline (ODA) and 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) as co-monomers, and nadic anhydride as an end cap reagent. The adhesives with different MDA and ODA contents were examined in terms of their structure, thermal stability, mechanical properties, and adhesive performance. They have glass transition temperatures (T g ) about 400°C, with thermal stability up to 500°C. The effect of diamine monomer compositions on adhesion performance and processability of the copolyimides were studied. The copolyimides exhibited adhesion strength up to 16.3 MPa at room temperature. Nadic end capped MDA-BTDA-ODA copolyimide resins gained adjustable and controllable processability with the addition of ether bridged aromatic segments. The copolyimide adhesive with equimolar composition of MDA:ODA is distinguished form the both commercial PMR-15 and LARC RP-46 polyimides in terms of its better processability and mechanical performance.

Tough Structural Adhesives with Ultra-Resistance to Both High and Cryogenic Temperature

“…High heat resistance is dependent on the high thermostability of the polymer structure, which is described by decomposition temperature (T d ) and glass transition temperature (T g ). Differently, durability to cryogenic temperature is closely related to toughness, which is determined by the structural flexibility at low temperatures [ 4 , 5 , 6 ]. To achieve these desired properties, careful structure design and synthesis are necessary.…”

“…Moreover, polyurethane adhesives represent healthy risks if not handled properly. Polyimide and bis-maleimide adhesives are the representatives of high-temperature polymers as they have extremely high T g (280~400 °C) and decomposition temperature (T 5% = 400~500 °C) [ 6 , 17 , 18 , 19 ]. However, their extremely high price and poor processibility largely restricted their applications.…”

Preparation and Properties of Electrospun Phenylethynyl—Terminated Polyimide Nano-Fibrous Membranes with Potential Applications as Solvent-Free and High-Temperature Resistant Adhesives for Harsh Environments

“…PI adhesives have been becoming one of the most promising materials for high-temperature adhesion in aerospace and aviation industries [7]. Up to now, the PI adhesives are mainly applied in the forms of liquid poly(amic acid) (PAA) precursors [8][9][10], preimidized PI varnishes, or solid B-staged PI films [11,12], or the thermoplastic PI powders [13]. The liquid-type PAA or PI adhesives are usually suffered from the low solid contents (usually less than 40 wt%) due to the limited solubility of the PAA or PI resins in the solvents, poor storage stability due to the degradation of PAA in thermal or humid environments, low adhesion efficiency due to the time-consuming curing procedures for PAA imidization, unsatisfied adhesion reliability due to the possible pinholes or voids existed in the PI adhesives caused by the releasing of solvent or water by-products in the PAA imidization, and so on.…”

Research Progress and Application of Polyimide-Based Nanocomposites

“…The reaction of dianhydrides and diamines subsequently formed PAA and then converted to PI through thermal/chemical imidization. Typically, most high-performance aromatic PIs adopt the PAA imidization route, ascribing to their being poorly soluble in common solvents [ 75 , 76 ]. Dianhydride and diamine require purification, such as sublimation, to achieve stoichiometric balance, thus obtaining the high viscosity of the PAA solution.…”