纳米微晶纤维素对炭黑补强天然橡胶力学性能和动态性能的影响

THE EFFECTS OF NANOCRYSTALLINE CELLULOSE IN THE MECHANICAL AND DYNAMIC PROPERTIES OF NATURAL RUBBER REINFORCED BY CARBON BLACK

采用酸水解工业微晶纤维素(MCC)制备纳米微晶纤维素(NCC),将其与天然胶乳共凝沉,混炼时加入炭黑(CB),制备了天然橡胶(NR)/NCC/CB复合材料,研究了NR/NCC/CB和NR/NCC/CB/RH(间苯二酚-六亚甲基四胺络合物)复合材料的力学性能和动态性能,并与NR/CB体系的性能进行对比.结果表明NCC可以均匀分散在天然橡胶基体中,且依拉伸方向取向,随着NCC替代炭黑的份数增加,Payne效应减弱,说明NCC本身并不构成强的填料网络,NR/NCC/CB与NR/CB比较,前者整体的网络化程度减弱,体系的损耗因子变化不大,NCC的加入改善了NR/CB的力学性能和抗屈挠龟裂性能,降低压缩疲劳温升和压缩永久形变,当NCC取代5～20 phr CB后,仍然保持高耐磨炭黑补强天然橡胶的耐磨耗性能.动态力学性能显示NR/NCC/CB的玻璃化转变温度较NR/CB变化不大,0℃的tanδ略有下降的同时60℃的tanδ明显降低.NR/NCC/CB/RH体系的Payne效应较NR/NCC/CB明显减弱,力学性能、抗屈挠龟裂性能和耐磨耗性能进一步改善,体系的压缩疲劳温升和压缩永久形变更小.

Nanocrystalline cellulose （NCC） is prepared by hydrolysis of microcrystalline cellulose （MCC） with acid. Natural rubber （NR）/NCC compound co-coagulates with NR latex and NCC suspension. Carbon black （CB） is added to NR/NCC composite in the blending process. The mechanical and dynamic properties of NR/NCC/CB, NR/NCC/CB/RH （resorcinol- hexamine complex） and NR/CB were investigated. The results show that NCC disperses uniformly and orientates to the stretching direction in the NR matrix. The Payne effect weakens with the increase of NCC fraction. It indicates that NCC doesn＇ t form a strong filler net and the total filler net in NR/NCC/CB is reduced in comparison with that of NR/CB. At the same time the variation of tan8 is not obvious. The addition of NCC can improve the mechanical property and the resistance to flex cracking of NR/CB and lower the heat build-up and the permanent set of dynamic compression. The abrasion resistance keeps constant when NCC is replaced by 5 - 20 phr of CB. DMA shows that the variation of Ts is not obvious,and the tan8 at 0℃ descends slightly while the tan8 at 60℃ descends obviously. The Payne effect of the NR/NCC/CB/RH system weakens sharply in comparison with that of the NR/NCC/CB system. And the mechanical property, the resistance to flex cracking and the abrasion resistance improve tremendously. At the same time, the heat buildup and the permanent set of the dynamic compression decrease further.