nit指标result硬度（绍尔A型）hardness度70±5扯断强度breaking strengthMPa＞10扯断伸长率ratio of breaking at elongation%＞150压缩永久变形（热空气200℃×22h）reshaped by compressing(hot gas 200℃×22h)压缩率20% radio of compressing 20%%≤50热空气老化（200℃×24h）hot gas aging(200℃×24h)硬度变化 changes of hardness扯断强度变化changes of breaking strengh扯断伸长率变化 changes of ratio of breaking at elongation度%%≤010≤-20≤-30耐液体（150℃×24h）fluid ressistant (150℃×24h)一号标准油体积变化 chan