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【单选题】

聚乙烯、聚丙烯、聚苯乙烯的主链结构完全一样,但它们的侧基位阻逐渐变大,它们的玻璃化转变温度从低到高的顺序是

A.
聚乙烯 < 聚丙烯 < 聚苯乙烯
B.
聚丙烯 < 聚乙烯 < 聚苯乙烯
C.
聚苯乙烯 < 聚乙烯 < 聚丙烯
D.
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【单选题】Desperately short of living space and dangerously prone to flooding, the Netherlands plans to start building homes, businesses and even roads on water. With nearly a third of the country already cover...

A.
most parts of the country are covered by water
B.
the country is constantly threatened by floods
C.
it will promote the cultivation of flowers
D.
people think it better to live on water

【单选题】2、下列聚合物中,玻璃化转变温度从高到低的正确次序是

A.
D. PE、PC、PS、PP
B.
A. PS、PC、PP、PE
C.
B. PC、PS、PP、PE
D.
C. PP、PC、PE、PS

【单选题】下列关于主转变温度的描述错误的是( )。

A.
Tg:由于分子链运动活化
B.
Tm:由于晶格破坏
C.
Tf:由于整个分子链质心产生相对移动