问题 问答题 简答题

简述装饰涂料的主要技术性质。

答案

参考答案:

1)耐污染性

建筑涂料的耐污染性用白度受污染损失百分数表示,测定用的污染物是1:1的粉煤灰水悬浊液,用改悬浊液反复污染涂膜一定的次数,测其白度损失率,损失率越小,耐污染性越好

2)耐久性涂料的耐久性包括耐冻融性、耐洗刷性、耐老化性

耐冻融性:是涂层在-20OC、23OC和50OC下各处理3h,经过多次循环后不出现涂层开裂或脱落的性能。

耐洗刷性:表示涂料受雨水长期冲刷时的性能

耐老化性:受大气中光、热臭氧等因素作用,涂层会发粘或变脆,失去原有强度和柔性,从而使得涂层开裂、脱落、粉化和变退色

3)耐碱性:测定方法将涂层浸泡在氢氧化钙饱和溶液中一定时间检查有无气泡、剥落和变色现象

4)最低成膜温度:水乳型涂料是通过涂料中的微细颗粒凝聚而成膜的,成膜只能在某一最低温度以上才能实现,这个最低温度就是最低成膜温度。

单项选择题
填空题

World Water Shortage


A new study warns that about thirty percent of the world’s people may not have enough water by the year 2025.
A private American organization called (1) Action International did the new study. It says (2) than three-hundred-thirty-five-million people (3) enough water now. The people live in twenty-eight (4) . Most of the countries are in Africa or the (5) East.
P-A-I researcher Robert Engelman says (6) the year 2025, about three-thousand-million people (7) lack water. At least 18 more countries are (8) to have severe water problems. The demand (9) water keeps increasing. Yet the amount of water on Earth (10) the same.
Mr. Engelman says the population in countries that lack water is (11) faster than in other parts of the world. He says (12) growth in these countries will continue to (13) .
The report says lack of water in the future may (14) in several problems. It may increase health (15) . Lack of water often means drinking (16) not safe. Mr. Engelman says there are problems (17) over the world because of diseases, such as cholera, (18) are carried in water. Lack of water may also result (19) more international conflict. Countries may have to (20) for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.