问题 名词解释

试以大分子链滑动学说说明炭黑的补强机理。

答案

参考答案:

橡胶大分子能在炭黑表面上滑动,从而消除掉外来的一部分能量。炭黑粒子表面的活性不同,有少数强的活性点以及一系列能量不同的吸附点。吸附在炭黑表面上的橡胶链可以有各种不同的结合能量,有多数弱的范德华力的吸附以及少量强的化学吸附。吸附的橡胶链段在应力作用下会滑动伸长,发生形变,使外力对其做功,能量分散、消耗,而橡胶高分子长链不会发生断裂,相当于强度增加。

完形填空
阅读下面短文,掌握其大意,然后从36—55各题所给的四个选项(A、B、C、D)中,选出最佳选项。
The Orkney Islands are about 14 kilometres from the north coast of Scotland. They are mostly low-lying, except for Hoy which has the highest sea cliff(峭壁) in Britain. The   36 and the climate are good in Orkney,  37 there are a lot of farms.
To get to Orkney you have to fly or go by  38 . Ships bringing passengers come from Aberdeen every week. They also bring food, machines and so on. Most Orkney farmers   39  cows or sheep. Because of this, grass is the most  40 crop on the islands. One of the islands has sheep which  41 sea plants   42  grass---they are  43 , but very strong and healthy.
Many people in the Orkney Islands are fishermen. Some go a long way out to  44 to catch large fish,   45 others catch  46 like crabs(螃蟹) and lobsters(龙虾),near the shore. The islanders  47 the crab meat and then pack it and send it to the  48 . They do not cook the lobsters. They send them  49 to restaurants in many of the large  50 of Europe. Most of the islands have their own  51 but of course some of them are very small---with only one group of children from five to ten years old. In fact there are  52 young people at all on the quietest islands. Usually they go the main town of Kirkwall,  53 modern lives.
Some people come from other parts of Britain to find a  54 life on the islands. Everyone is very friendly and they all know each other. Things are changing slowly, but the old way of life   55 continues.
36.A.land         B.hill         C.mountain     D.forest
37.A.yet          B.but          C.or           D.and so

 

 
38.A.train        B.bus        C.boat         D.car

39.A.feed         B.buy         C.kill         D.like
40.A.useless      B.harmful      C.important    D.unimportant

 

 
41.A.drink        B.eat          C.produce      D.plant

42.A.instead of   B.instead      C.for          D.with
43.A.small        B.big          C.large        D.tall
44.A.field        B.sea          C.sky          D.space
45.A.when         B.since            C.while           D.for
46.A.birds        B.tigers           C.lions            D.shellfish
47.A.cook         B.burn            C.sell            D.buy
48.A.desert       B.ship            C.island          D.mainland
49.A.alone        B.alive            C.about            D.asleep
50.A.libraries    B.lakes            C.cities           D.banks
51.A.zoos         B.colleges        C.schools         D.universities
52.A.very few     B.a lot of        C.a great many    D.a number of
53.A.live         B.to live         C.living          D.lives
54.A.happy        B.busy            C.quiet            D.noisy
55.A.also         B.still            C.never            D.nearly
单项选择题