Effect of blocking agents on the shock absorbing properties of the films of polyurethane adhesives

Abstract

Various 4,4‐diphenylmethane diisocyanate (MDI0) based polyurethane adhesives have been developed using polyethylene glycols (PEG) of different moleclar weights. The formulations were modified using different blocking agents to inhibit the isocyanate‐moisture reaction. Composites of poly(methyl methacrylate) sheets were developed in which these adhesives gave transparent films and their shattering characteristics were tested in a bullet firing machine developed here. The damaged area was measured and used to characterize the adhesive strength. The molecular weight of the soft segment (diol) and the nature of the blocking agent both were found to affect drastically the urethane film properties.

Synthesis and characteristics of aqueous reactive urethane oligomer containing sulfoisophthalate sodium salt

“…Currently, other types of reactive urethane oligomer such as acrylic type [9][10][11][12][13][14][15][16][17][18][19] containing vinyl group and epoxy type [20][21][22][23][24][25][26][27][28][29] containing epoxide group have been developed. In past studies of isocyanate type, for example, Roy and Kumar 3 have used phenol, bisphenol, and hydroquinone as capping agent to synthesize reactive urethane oligomer. They studied the effects of PEG molecular weight and the variety of capping agents to the adhesive property and shock resistance of the formative substances.…”

“…[1][2] To improve the reactivity of urethane oligomer, the isocyanate type [3][4][5][6][7][8] was generally produced by capping the NCO group of PU prepolymer. Currently, other types of reactive urethane oligomer such as acrylic type [9][10][11][12][13][14][15][16][17][18][19] containing vinyl group and epoxy type [20][21][22][23][24][25][26][27][28][29] containing epoxide group have been developed.…”