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. 可以通过引入少量的第三单体，使得乙丙橡胶能够用硫黄进行硫化，从而获得更全面的性能。

[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. 研究发现二烯烃可以在乙丙橡胶聚合的过程中加入，这样可以使其中的一个双键优先参与聚合，而另一个双键作为侧基用于硫化反应。

[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. 乙丙橡胶几乎是性能最为全面的通用橡胶，它除了不耐有机油类，几乎可以满足所有的应用。

[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. 除了橡胶工业外，它们还能作为润滑油的黏度改性剂使用；它们加入到聚烯烃类材料中可以提高低温抗冲击性能；它们和聚烯烃树脂或其他热塑性树脂共混，可以制备热塑性弹性体。

Exercises

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

2. Put the following words into English.

二元乙丙橡胶　　三元乙丙橡胶　　乙烯　　　　丙烯　　　二烯烃

三元共聚物　　　导电性能　　　　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