Lesson 8　Ethylene Propylene
Rubber (EPR)

New Words

Notes

[1] The greater versatility of a sulfur curable elastomer was sought, and found by the incorporation of limited amounts of a third monomer into the polymer. 可以通過引入少量的第三單體，使得乙丙橡膠能夠用硫黃進行硫化，從而獲得更全面的性能。

[2] Dienes were found which were compatible with the EPM polymerization process, and which had one double bond that would preferentially polymerize to leave a pendant double bond available for vulcanization. 研究發現二烯烴可以在乙丙橡膠聚合的過程中加入，這樣可以使其中的一個雙鍵優先參與聚合，而另一個雙鍵作為側基用于硫化反應。

[3] The ethylene propylene rubbers are probably the most versatile of the general purpose elastomers, and can be compounded in nearly the full spectrum of applications not requiring resistance to hydrocarbon oils. 乙丙橡膠幾乎是性能最為全面的通用橡膠，它除了不耐有機油類，幾乎可以滿足所有的應用。

[4] Outside the rubber industry, they are used as viscosity modifiers in lubricating oils; they improve low temperature impact strength when added to polyolefins at low levels; and they form thermoplastic elastomers when blended in higher ratios with polyolefins or other thermoplastic resins. 除了橡膠工業外，它們還能作為潤滑油的黏度改性劑使用；它們加入到聚烯烴類材料中可以提高低溫抗沖擊性能；它們和聚烯烴樹脂或其他熱塑性樹脂共混，可以制備熱塑性彈性體。

Exercises

1. Translate the first and second paragraphs of the text into Chinese.

2. Put the following words into English.

二元乙丙橡膠　　三元乙丙橡膠　　乙烯　　　　丙烯　　　二烯烴

三元共聚物　　　導電性能　　　　耐候性

Thermal Properties of EPDM

EPDM is largely unaffected by weather with very good resistance to ozone. DuPont literature quotes EPDM products which were exposed to 10000 parts per hundred million of ozone for 1000 hours in air, at room temperature, without cracking. Raw gum elastomer manufacturers’ literature indicate upper continuous heat aging temperature limits in air, anywhere from 126℃ to around 150℃. Introducing time into this equation, one scenario might be: one cumulative month at 165℃， one cumulative year at 125℃， and five cumulative years at 100℃.

Low temperature flexibility is very good and compares well with NR, and like NR and SBR, EPDM (with a lower polarity than NR) has very poor oil resistance. The use of EPDM is dominant in roof membrane linings and extruded channels for windows. EPDM has also been used as a blend with NR in tire sidewalls to improve resistance to cracking by ozone attack. The excellent electrical resistance of EPDM promotes its use in medium and high voltage cable covers. Automotive applications of EPDM would include radiator and heater hoses and weather strips.

Words and Expressions