Interaction of carboxyl‐containing butadiene–styrene rubbers with polyamides and ε‐caprolactam

Abstract

Mixtures of carboxylated butadiene–styrene rubbers containing 30% styrene, and 1, 3, 4, 5, 10, and 15% methacrylic acid (MAC) were investigated with ε‐caprolactam in a melt or in masticated mixtures for 10 hr. at 220°C. The lactam was found to add to the rubber both in the presence and in the absence of water, as was shown by extraction of the resultant specimens with acetone, followed by formic acid and determination of nitrogen in the extracts. The compression heating of carboxylated butadiene–styrene rubber containing 30% styrene and 1% methacrylic acid with ε‐caprolactam at 200–220°C. leads to addition of the lactam to the rubber. BF3 served as reaction catalyst. Methods have been developed for the synthesis of graft and modified carboxylated butadiene–styrene rubbers and polyamides through the stage of rubber acid chlorides and sodium (potassium) derivatives of the polyamides. The rubber acid chlorides are obtained according to the reaction: The polyamides derivatives, according to the reaction: and Modification of the carboxylated butadiene–styrene rubber with ε‐caprolactam was carried out according to the reaction: or Rubbers with a MAC content of 0.3% to 10% were employed. The modified rubbers possess greater strength characteristics than the original carboxylated polymers. They are less soluble in pure benzene and soluble in benzene–ethyl acetate mixtures. Insoluble, crosslinked polymers are obtained on reaction of the rubber acid chlorides with sodium substituted polyamides. Under particular conditions soluble products are formed. The products possess enhanced adhesion to polyamide films and ensure a strong bonding between rubber and fabric in rubber textile goods.