Study on "fibro composites"
-morphology of PBT/PE blend
Kitagawa Kazuo; Semba Takeshi; Hamada Hiroyuki
Abstract:In a poly (buthylene terephthalate) (PBT) and polyethylene (PE) immiscible blend, we found that a PBT component could form fibro reinforcements in PE matrix during compounding and injection molding. Extruded strands were subjected to drawing at cooling processes during compounding. Injection moldings were fabricated with the compounded pellets at various processing conditions in which cylinder temperatures were 190, 210, 215 and 220 deg.. Tensile tests and scanning electron microscopic observations were performed using drawing and non drawing strands and injection moldings. The fibro reinforcements of PBT were formed in skin layer of the extruded strand, while the PBT component was sphere shape in core layer. The ratio of PBT fibro reinforcement in the drawing strand was higher than that in the non drawing strand, so that tensile modulus and strength of the drawing strand increased. At 190 deg. of cylinder temperature, which was lower than the melting point of PBT, the fibro reinforcements could be hardly formed and the tensile fracture aspect indicated quite brittle behavior. At 215 deg. which was between the first and the second melting point (Tm2), the ratio of fibro reinforcement in the injection molding was the highest among all moldings. At 220 deg., which was almost the same as Tm2, the PBT component was completely dissolved and next formed much more spherical shape in the core layer than the 215 deg. molding during injection processing. Key Words:fibro-composites, PBT/PE blend, morphology