Formation mechanism of polymer whiskers obtained with polymerization

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It has been reporeted by authors that whiskers of wholly aromatic polyesters such as poly (p-oxybenzoyl) (POB) could be obtained in a high temperature solution polymerization. Thease whiskers have an almost uniform width of 1-1.5 um and a length of 20-100um. The formation mechanism containing three steps, tha lamellar crystallization of oligomers polymerized in solution, the spiral growth of oligomer lamellae and the post polymerization of oligomers between lamellae, has already been suggested by us.In this project, morphology and formation mechanism of poly (4'-oxy-4-biphenylcarbonyl) (POBP) crystals obtained by solution polymerization were firstly treated. It was concluded that the formation mechanism of the bundlelike aggregates of fibrillar crystals in POBP is fundamentally simillar to that in POB whiskers. Secondly the copolymerization effects of m-acetoxybenzoic and 4'-acentoxy-biphenyl-4-carboxylic acid on the morphology of POB whiskers were studied. The experimental results strongly supported our proposal for the formation mechanism of whiskers which was consisited of crystallization of oligomers with a critical length as lamellae from solution and solid state polymerization of oligomers between the lamellae. Finally, the formation mechanism of poly (p-oxycinnamyl) spherical products during solution polymerization was treated. The formation of these spherical product could be understood by overlapped phase diagram of melting depression curve and consolute curve. This new morphology control of rigid rod polymers during polymerization examind in detail.