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英语翻译The effect of methanol on the grafting rate was clearly

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解决时间 2021-08-21 13:46
英语翻译
The effect of methanol on the grafting rate was clearly demonstrated by grafting of PE
in a mixture of styrene and methanol (Fig 1).By dilution of styrene with methanol the
concentration of styrene inside PE decreases,the viscosity increases and due to the gel-effect
the grafting rate and yield increase until optimal concentration of monomer is reached.
The methanol being almost completely insoluble in PE has no direct effect on viscosity of the
amorphous region of the PE where grafting take place.Its sole function is to reduce the
concentration of the styrene in the PE (Machi et al.,1970).When less styrene is present to
swell the growing polystyrene radicals they are less mobile and the rate of their mutual
termination is lower.The decreased radical termination rate overcompensates for decrease in
the rates of initiation and propagation which also accompany the monomer dilution.Hence
the decrease in monomer concentration results in longer polystyrene chains and higher overall reaction rate.If the monomer will be diluted with the solvent which swells polymer equally or
better than monomer the decrease of grafting rate with solvent addition could be expected.
It is known that crosslinking of PE influences its swelling properties.Accordingly it could be
expected that pre-crosslinking of PE influences the rate and yield of grafting as well.We
demonstrated this by pre-crosslinking PE and by its subsequent grafting with styrene after the
trapped radicals had been annealed out.Grafting was induced by simultaneous irradiation
(Fig 2).
For pre-crosslinked PE the grafting rate is higher than for the uncrosslinked polymer.
We interpret the increase of grafting yield with crosslink density by hindered mobility of
polymer chains and in terms of the gel-effect,since the monomer concentration within the
film is reduced,viscosity increased and the rate of termination of growing grafted chains
descreases.
Two solvents different in chemical structure and radiation sensitivity were used for
swelling of PE during radiation crosslinking:benzene with aromatic structure and high
radiation resistivity and hexane similar in chemical structure and radiation sensitivity to PE.
If the PE was swollen with benzene and then crosslinked the subsequent increase in the
grafting yield was lower than in the case when dry polyethylene was crosslinked.
This result suggested that crosslinking could be less efficient in the presence of benzene.
When hexane was used as the swelling agent similar results were obtained as with benzene.
In order to obtain more direct information about the influence of swelling agent on PE
crosslinking we investigated the crosslinked polyethylene for its elastic modulus in the molten
state.
最佳答案

影响甲醇的接枝率为清楚地表明了接枝聚乙烯
在混合的苯乙烯和甲醇(图1 ) .稀释苯乙烯,甲醇的
浓度苯乙烯内体育减小,粘度增加,由于凝胶效应
接枝率和产量增加,直至最佳单体浓度达到.
甲醇是几乎完全不溶于体育没有直接影响粘度
非晶地区体育在嫁接发生.其唯一的功能是减少
苯乙烯浓度的聚乙烯(麻吉等人. , 1970年) .当少苯乙烯是目前
膨胀聚苯乙烯自由基越来越少,他们是移动的速度和其相互
终止较低.减少自由基的终止率下降overcompensates
率的发起和传播也伴随单体稀释.从此
减少单体浓度结果不再聚苯乙烯链和创新高,整体反应速度.如果单体将稀释溶剂的聚合物同样或肿
优于单体的接枝率降低溶剂除了可以预期.
据了解,交联聚乙烯的溶胀性能的影响.因此可以
预计前交联聚乙烯的影响率和产量的影响以及嫁接.我们
证明了这一点通过预先交联聚乙烯及其随后与苯乙烯接枝后
被困自由基进行了退火.嫁接诱导同步辐射
(图2 ).
预先交联聚乙烯的接枝率高于uncrosslinked聚合物.
我们解释的增加,接枝率与交联密度的阻碍流动性
聚合物链,并在规定的凝胶作用,因为单体浓度范围内
电影降低,粘度增加的速度越来越终止嫁接链
descreases .
两个不同的溶剂中的化学结构和辐射敏感性用于
肿胀在辐射交联聚乙烯:苯与芳香结构和高
辐射电阻和正己烷相似的化学结构和辐射敏感性体育.
如果体育肿胀苯然后交联随后增加
接枝率低于干燥的情况下,是交联聚乙烯.
这一结果表明,交联可能是效率较低,在场的苯.
当正己烷被用来作为溶胀剂类似的结果,得到的苯.
为了获得更多的直接信息的影响,溶胀剂对体育
我们研究了交联交联聚乙烯的弹性模量在熔融
状态.
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