| 摘要 |
<p>A thermoplastic elastomer compsn. contains (a) 25-85 wt % of an amorphous ethylene-alpha-olefin copolymer with X-ray crystallinity 4 (2.5) wt % and a tensile strength is not 10 (>50) kg/cm2, and (b) 75-15(65-30) wt % of a crystalline block copolymer of propylene and ethylene contg. 1-25 (2.5-15) esp. 5-10 wt % ethylene and with X-ray crystallinity >25 wt %. The compsn. vary from soft and rubber, to rigid, and have wide appln. They can be mixed with other synthetic polymers, can be reinforced (e.g. with fibres) and can be painted or lacquered. A mixt. contg. is not >20 (5-15) wt % polyethylene, pref. of density is not 0.95, is suitable for cable jackets and car bumpers. The compsn. combines good elastic properties with easy processing, similar to that styrene block copolymers with a conjugated diene. The compsn. is cheaper, and more resistant to heat and to ageing than the styrene block copolymers, and can be used over a wide temp. range. The tensile strength is greater than that of compsns. contg. propylene homopolymers. The compsn. is not vulcanised.</p> |
