Polyamic acid resin preparation

The aromatic diamines and dianhydrides used in the preparation of the polyamic acid resins and the diamic acid additives are listed in Figure 1. The 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4,4 -oxydianiline (4,4 -ODA), and 3,3 -diaminodiphenylsulfone (3,3 -DDS02) were obtained from commercial sources. The remaining monomers were obtained as experimental materials as follows (1) 4,4 -bis(3,4-dicarboxyphenoxy) diphenylsulfide dianhydride (BDSDA) from General Electric Corporate R D Center (2) 4,4 -oxydiphthalic anhydride (ODPA) from Occidental Chemical Corporation (3) 2,2-bis[4(4-aminophenoxy)phenyl]hexafluoropropane (4-BDAF) from Ethyl Corporation and (4) 2,2-bis[4(3-aminophenoxy)phenyl]hexafluoropropane (3-BDAF) and 3,3 -oxydianiline (3,3 -ODA) from Mitsui Toatsu, Inc. 

Control films of the polyamic acid resins were prepared by casting the solution of the resin onto soda-lime glass plates using an aluminum blade with the gap set to obtain ... 

Pater also prepared a semi-2-IPN, LaRC-RP41, from a mixture having the ratio of 80 20 of thermosetting PMR-15 to LaRC-TPI polyamic acid(44). LaRC-RP41 exhibited significantly improved toughness and micro-cracking resistance, but showed somewhat poorer mechanical properties at 316 °C, compared to those of PMR 15 near resin (see Fig. 13). 

Photosensitive resins consisting of pre-imidized aromatic polyamic acids, (III), having a light transmittance of 365 nm and a low residual stress after cure were prepared by Dueber [3] and used for coating silicon wafers. 

Films containing the diamic acid additives were prepared by dissolving 3-15 weight percent (based on resin solids) of the additives into the polyamic acid solutions, then casting and curing as above. 

Polyimides for use in electronics must be carefully selected and prepared to produce consistent materials with the desired properties. Furthermore, the impact of polymer processing on the circuitry must be carefully considered. In particular, the molecular weight of the polyimide resin must be controlled for successful application and imaging, which means that the molecular weight of the precursor polyamic acid must be controlled. 

NASA-Langley Research Center. The characteristics of the samples in the two sets are given in Table I. The first set of samples were lap-joints of Pasa-Jell cleaned Ti-6-4 panels bonded with one polyimide resin adhesive. The resin adhesive was prepared from benzophenone tetracarboxylic acid dianhydride (BTDA) and m,m -diaminobenzophenone (m,m DABP). The structures of these compounds are given in Table II. The uncured adhesive was applied on the adherend in the polyamic acid stage from either diglyme or DMAC solution and then heat cured to the polyimide resin form. This condensation polymerization reaction is shown below. 

The uncured adhesive was applied on the adherend in the polyamic acid stage from the solvent diglyme and then heat-cured to the polyimide resin form. Tensile lap shear sandwich specimens were prepared by bonding 13 x 2.5 x 0.1 cm Ti-6-4 coupons with a 1.3 cm overlap. Typically, the coated coupons were air dried for 30 min at room temperature and then for 30 min at 60 C. Five successive coats were applied. The panels were overlapped at room temperature, placed under a constant pressure of 50 psi, and heated to 300°C at a rate of 5°C min""l. The specimen was held at 300°C for... 

---