Spatial distribution of supraglacial debris thickness on glaciers of the China-Pakistan Economic Corridor and surroundings

Debris-covered glaciers,characterized by the presence of supraglacial debris mantles in their ablation zones,are widespread in the China-Pakistan Economic Corridor(CPEC)and surroundings.For these glaciers,thin debris layers accelerate the melting of underlying ice compared to that of bare ice,while thick debris layers retard ice melting,called debriscover effect.Knowledge about the thickness and thermal properties of debris cover on CPEC glaciers is still unclear,making it difficult to assess the regional debris-cover effect.In this study,thermal resistance of the debris layer estimated from remotely sensed data reveals that about 54.0%of CPEC glaciers are debris-covered glaciers,on which the total debris-covered area is about 5,072 km2,accounting for 14.0%of the total glacier area of the study region.We find that marked difference in the extent and thickness of debris cover is apparent from region to region,as well as the debris-cover effect.53.3%of the total debris-covered area of the study region is concentrated in Karakoram,followed by Pamir with 30.2%of the total debris-covered area.As revealed by the thermal resistance,the debris thickness is thick in Hindu Kush on average,with the mean thermal resistance of 7.0×10^-2((m^2∙K)/W),followed by Karakoram,while the thickness in western Himalaya is thin with the mean value of 2.0×10^-2((m^2∙K)/W).Our findings provide a basis for better assessments of changes in debriscovered glaciers and their associated hydrological impacts in the CPEC and surroundings.

EFFECT OF NANOCRYSTALLINE CELLULOSE ON THE CURING CHARACTERISTICS AND AGING RESISTANCE PROPERTIES OF CARBON BLACK REINFORCED NATURAL RUBBER

This work focused on the effect of nanocrystalline cellulose （NCC） on the curing characteristics, aging resistance and thermal stability of natural rubber （NR） reinforced with carbon black （CB）. Sharing the same fillers loading of 45 parts per hundred rubber （phr）, NR/NCC/CB composites with different NCC/CB ratios （i.e. 0/45, 5/40, 10/35, 15/30, 20/25 phr） were prepared and analyzed. Resorcinol and hexamethylene tetramine （RH）, acting as the modifier in NR/NCC interface, was also discussed for its influence. The result showed that an relatively higher ratio of NCC/CB led to a lower torque, a shorter cure time （Tg0）, a slightly longer scorch time （Ti0） and a bigger vulcanization rate constant （K）. This tendency suggested that the existence of NCC accelerated the vulcanization process. Additionally, modified by RH, NR/NCC/CB compounds exhibited a short T10 and a elevated torque. And a moderate RH content would lower the E of vulcanization. A 10 phr substitute of CB by NCC can help to improve aging resistance in terms of mechanical properties. In a high temperature aging condition, composites with 10 phr NCC also performed the highest storage modulus （G＇） among composites tested. A moderate NCC content contributed to the best retention of G＇ after high temperature aging, so did the incorporation of RH. With the partial replacement of CB by NCC, the temperature of 5% weight-lose had a slight drop and the apparent crosslink density showed a decrease. Thanks to the interaction of RH with both NR and NCC, composites showed an improvement in apparent crosslink density after modified by RH.