The effect of third component content on automotive fuel resistance of NR/FKM blend was investigated by determined the percentages of swelling as shown in Figure 8. For a given blend composition, the percentages of swelling increased with increasing immersion time. The rate of swelling increased exponentially with time.
For the ENR added NR/FKM blends, it is interesting to note that the percentage of swelling of NR/FKM blend without ENR was greater than that of NR/FKM blend with ENR for all automotive fuel studies. With increasing ENR content, the percentage of swelling after 100 hours of immersion time of NR/FKM blends was found to decrease when ENR content increased from 2.5 to 10 phr. The NR/FKM blend with high ENR content showed lower degree of swelling than those of the lower ENR content. Because of the improvement of interaction between NR and FKM by ENR molecule at enough ENR content, a result in compatiblized phase in microstructure was occurred. However, the presence of ENR which polar rubber was also increased the oil resistance of the blend.
For the PI-ME added NR/FKM blends, the reverse results were observed. The percentage of swelling of NR/ FKM blend without PI-ME was lower than that of NR/ FKM blend with PI-ME. With increasing PI-ME content, the percentage of swelling of NR/FKM blends was found to increase especially at 10 phr. Physically, PI-ME added NR/FKM blends had trend to soft and sticky with increasing PI-ME content. PI-ME would be plasticizer or lubricant in this NR/FKM blend and then allowed automotive fuels penetrate in to the rubber phase. Furthermore, the lower degree of crosslinking in rubber blend in the presence of PI-ME and soft characteristic, a result in higher degree of automotive fuel penetration into rubber phase was occurred. The another reason of high automotive fuel swelling of PI-ME added NR/FKM blend is nonautomotive fuel resistance of PI-ME, then increasing PI-ME content result in high percentage of swelling of NR/FKM blend in automotive fuel.
It was found that the percentage of swelling of NR/ FKM blend with ENR in gasoline-based fuel was quite greater than that in diesel-based fuel (Figure 8(a)). Gasoline is predominantly a mixture of paraffins, naphthanes, and olefins, while diesel is composed of about 75% saturated hydrocarbons, and 25% aromatic hydrocarbons [10]. The gasoline-based fuels have a smaller average molecular size than that of diesel-based fuel. Thus gasoline-based fuels were penetrated in ENR added rubber sample easily than diesel-based fuels. This result was as same as previous report [11]. However, for comparing in percentage of swelling of these rubber blends in gasoline-based fuel, gasoline and gasohol, it was found no more different. For NR/FKM blends with PI-ME, the percentage of swelling in all automotive fuel studies was not considerable different (Figure 8(b)).
ผลของเนื้อหาส่วนที่ 3 ความต้านทานต่อเชื้อเพลิงยานยนต์ของผสม NR/FKM ถูกตรวจสอบโดยกำหนดเปอร์เซ็นต์ของการบวมดังแสดงในรูปที่ 8 สำหรับองค์ประกอบที่กำหนดผสม เปอร์เซ็นต์ของการบวมเพิ่มขึ้น ด้วยการเพิ่มเวลาแช่ อัตราการบวมเพิ่มขึ้นเป็นทวีคูณเมื่อ มีเวลา สำหรับ ENR ที่เพิ่มผสม NR/FKM เป็นที่น่าสนใจทราบว่า เปอร์เซ็นต์ของการบวมของผสม NR/FKM โดย ENR คือมากกว่าของ NR/FKM ผสม ENR ศึกษาเชื้อเพลิงยานยนต์ทั้งหมด ด้วยการเพิ่มเนื้อหา ENR เปอร์เซ็นต์การบวมหลังจากผสม 100 ชั่วโมงเวลาแช่ของ NR/FKM พบลดลง ENR เนื้อหาเพิ่มขึ้นจาก 2.5 10 phr. ผสม NR/FKM มีเนื้อหาระดับสูง ENR พบระดับล่างบวมกว่าของ ENR ล่างเนื้อหา ผลในระยะ compatiblized ในต่อโครงสร้างจุลภาคเกิดขึ้นเนื่องจากการพัฒนาของปฏิสัมพันธ์ระหว่าง NR และ FKM โดยโมเลกุล ENR ที่เนื้อหาพอ ENR อย่างไรก็ตาม ของ ENR ยางที่ขั้วโลกยังถูกเพิ่มต้านทานน้ำมันของผสม For the PI-ME added NR/FKM blends, the reverse results were observed. The percentage of swelling of NR/ FKM blend without PI-ME was lower than that of NR/ FKM blend with PI-ME. With increasing PI-ME content, the percentage of swelling of NR/FKM blends was found to increase especially at 10 phr. Physically, PI-ME added NR/FKM blends had trend to soft and sticky with increasing PI-ME content. PI-ME would be plasticizer or lubricant in this NR/FKM blend and then allowed automotive fuels penetrate in to the rubber phase. Furthermore, the lower degree of crosslinking in rubber blend in the presence of PI-ME and soft characteristic, a result in higher degree of automotive fuel penetration into rubber phase was occurred. The another reason of high automotive fuel swelling of PI-ME added NR/FKM blend is nonautomotive fuel resistance of PI-ME, then increasing PI-ME content result in high percentage of swelling of NR/FKM blend in automotive fuel. It was found that the percentage of swelling of NR/ FKM blend with ENR in gasoline-based fuel was quite greater than that in diesel-based fuel (Figure 8(a)). Gasoline is predominantly a mixture of paraffins, naphthanes, and olefins, while diesel is composed of about 75% saturated hydrocarbons, and 25% aromatic hydrocarbons [10]. The gasoline-based fuels have a smaller average molecular size than that of diesel-based fuel. Thus gasoline-based fuels were penetrated in ENR added rubber sample easily than diesel-based fuels. This result was as same as previous report [11]. However, for comparing in percentage of swelling of these rubber blends in gasoline-based fuel, gasoline and gasohol, it was found no more different. For NR/FKM blends with PI-ME, the percentage of swelling in all automotive fuel studies was not considerable different (Figure 8(b)).
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