问题 问答题 简答题

油基涂料的干燥机理?油度的长短对涂料性能有什么影响?

答案

参考答案:油基涂料的干燥属于“气干”的干燥类型,是指涂膜吸收空气中的氧气进行氧化聚合而形成网状结构的干膜。

以亚麻仁油为例,它的交联成膜分为三个阶段,

A.导入期,天然氧化剂被消耗

B.快速氧化期,伴随着增重10%,氧分子与脂肪酸中双键附近碳原子上活泼的氢反应生成过氧化氢基团C.复杂的自催化反应,消耗过氧化氢基团,产生自由基引发双键聚合并交联成膜。

油度表示脂肪酸与聚酯的比例,以醇酸树脂漆为例,长油度醇酸树脂含油量在60%以上,通常采用刷涂,其耐候性优良,亦制作外用装饰漆,船舶漆和金属保护漆等。中油度醇酸树脂含油量在50%~60%之间,其干燥快,保光耐候性较好使用范围广。其缺点为“口紧”刷涂性稍差。低油度醇酸树脂含油量在50%以下,与其他树脂的混溶性最好。

阅读理解

阅读理解。

阅读下面短文,并根据短文后的要求答题。(请注意问题后的词数要求)

       Psychology (心理学) tells us that many people hate to take risks. But it is good for us to take risks,

especially when the risk is to achieve a desired result. In that way, we become stronger and braver.

     Our human nature should be to take risks, but some people just sit and wish they didn't have the fear to move on.This is because of one or two failures in their lives. Please step out and don't let the past hold you back from living life to the fullest. Move forward and move on!

      In studying the psychology of taking risks, we find that human nature provides us with the desire to

experiment and take chances.

     Risk taking is a great benefit that allowed our ancestors ( 祖先) to become stronger and stronger day

by day. By taking risks they fought off enemies and discovered new land. This attitude has become a part of our modem culture.Riding a roller coaster is a common risk taking activity that even the average person seems to enjoy although they have the understanding that it is dangerous.

      Getting in a car each day is a risk. Getting out of bed is a risk. We need to take risks so that we can

finish many things. Astronauts take risks when they get inside a rocket; however, the things they achieve

are great. Businessmen take a risk when they buy parts of a company. However, without doing that, they

could not make more money.

     We need to take risks so that we can gain something. It is impossible to move forward in life, earn

money, enjoy a relationship, play a sport, or do anything else____. It is all part of the game. It's one of the most important parts of life.

1.  What is the main idea of the passage? ( Please answer within 10 words)

__________________________________________________________

2. Which sentence in the passage can be replaced by the following one?

   Don't let the failures that you have experienced prevent you from taking risks and living a meaningful life.

__________________________________________________________

3. Please fill in the blank in the last paragraph with proper words or phrases to complete the sentence.  

( Please answer within 10 words)

__________________________________________________________

4. Why do people ride a roller coaster although they know it is dangerous? ( Please answer within 10

words)

__________________________________________________________

5. Translate the underlined sentence in the first paragraph into Chinese.

__________________________________________________________

单项选择题