高分子材料工程專業(yè)英語課后材料文章Reading Materials

1、嘉興學(xué)院 高分子系 吳佰程整理Reading Materials第6單元Purification of Polymers聚合物的提純The usual purification operations used with low molecular weight compounds (for example, distillation and recrystallization) are usually not applicable to macromolecular compounds.針對低分子量化合物通常的提純方法，如蒸餾和重結(jié)晶通常都不能用于高分子化合物。Distillation, 蒸餾

2、Macromolecular compounds are not volatile and cannot simply be recrystallized from saturated solutions. One therefore has to be satisfied with extracting them in suitable solvents and thus removing the impurities.Volatilevoltail, 飛行的，易揮發(fā)的，快活的，爆炸性的，易激動的，反復(fù)無常的，短暫的。Extract, v，萃取，extraction, 萃取高分子化合物不是揮

3、發(fā)性的，而且不能簡單地從飽和溶液中再結(jié)晶。因此人們不得不用合適的溶劑來萃取這些高分子，從而去除雜質(zhì)。The purification effect of the extraction is in most cases rather slight because in many instances the impurity is held to the polymer by strong secondary valence forces. Secondary valence force, 次（化合）價(jià)力Hold to 堅(jiān)持，緊握在大多數(shù)場合，萃取的提純效果是很有限的，因?yàn)樵谠S多情況下雜質(zhì)被聚合物

4、強(qiáng)的次價(jià)力束縛。Consequently, one usually first dissolves the macromolecular compound and then precipitates it by addition of a nonsolvent. 因此，我們通常首先溶解高分子化合物，然后用非溶劑填加物把高分子沉淀下來。Precipitate，沉淀The precipitate comes out as a more or less strongly swollen gel. Come out，長出，（花）開，由。產(chǎn)生，由。出來，結(jié)果是，顯現(xiàn)，（污點(diǎn)）被去掉，（顏色）被褪去，（題

5、目）被解出，（商品）被展出，被供應(yīng)，（總數(shù)）計(jì)，總計(jì)Swell，溶脹，gel，凝膠，溶膠，sol，溶膠-凝膠法，sol-gel沉淀大體上以強(qiáng)烈溶脹的凝膠形式產(chǎn)生出來。And the impurities remain at least partly in solution. 而雜質(zhì)至少有一部分保留在溶液中。The gel can be removed by sedimentation if necessary, in the centrifuge. 如果需要的話，凝膠可以用離心機(jī)沉降移出。Usually it is necessary to repeat this precipitation

6、10-20 times. 通常這個(gè)沉淀過程有必要重復(fù)10到20次。The solvents and precipitating agents have to be carefully selected from case to case. 根據(jù)不同場合，溶劑和沉淀劑必須仔細(xì)選擇。Many vinyl polymers are easily dissolved in benzene and toluene and precipitate under addition of methanol. Toluence，甲苯Methanol，甲醇許多乙烯基聚合物容易溶解在苯或甲苯中，而在添加甲醇的情況下發(fā)

7、生沉淀。Methanol is a sort of general precipitating agent in which most polymers, both the benzene soluble ones and the water-soluble polymers, are insoluble. 甲醇是一種常見的沉淀劑，無論是苯溶還是水溶聚合物，大多數(shù)聚合物在甲醇里是不溶解的。Since methanol is miscible in all proportion both with benzene and with most other organic solvents and

8、also with water, it can be used as a precipitant in both cases, i.e., with organic and with aqueous polymer solutions.Miscible, 可混溶的，miscibility，相溶性（分子層面上的混溶）compatible,相容的， Compatibility,相容性（相層面上的混溶）因?yàn)榧状寂c苯等有機(jī)溶劑，與水都可以所有的比例混溶的。在有機(jī)和水的高分子溶液中，甲醇可以用來做沉淀劑。One has to expect that the polymers is somehow aff

9、ected by the extraction, regardless of whether this is done by heating or by precipitation. 聚合物受萃取過程的影響是肯定的，不管這個(gè)過程是通過加熱還是沉淀。Thus if one extracts with acids or bases, hydrolytic degradation usually causes a lowering in the degree of polymerization (for example, hydrolytic degradation of polysaccharid

10、es). Hydrolytic, 水解的，Degradation, 降解反應(yīng)。Polysaccharide, 多糖，聚糖因此如果我們用酸或堿來萃取，水解降解反應(yīng)通常導(dǎo)致聚合度降低，如聚糖的水解。In the process of dissolving and reprecipitation, one usually finds that low molecular weight components remain in solution (fractionation), and therefore the precipitated part has a higher average molec

11、ular weight and more uniform molecular weight distribution.Uniform, （尺寸、大小，形狀等）均一的，distribution,分布在溶解和再沉淀過程中，通常我們發(fā)現(xiàn)低分子量組分保留在溶液中（分級），因此，沉淀部分具有高的平均分子量，而且分子量分布更均一。This may or may not be desirable, but in any case one should be aware of it.這可能和我們的意，也可能不合我們的意，但是，無論什么情況，我們都應(yīng)該知道這一點(diǎn)。With synthetic polymers,

12、 purification may be avoided sometimes by choosing a method of synthesis where the polymer is immediately obtained in pure form. 對合成聚合物而言，提純過程有時(shí)是可以避免的。通過選擇合成方法，我們可以很快得到純的聚合物， Usually an extreme purification of the monomer is simpler and more effective than a later purification of the polymer. 通常單體的最

13、大程度的提純比聚合物后提純更簡單，而且也更有效。Initiators and other additives, such as emulsifying agents and protective colloids, are also selected wherever possible in a such way that they can remain in the polymer without causing problems.引發(fā)劑和其他添加劑，如乳化劑和保護(hù)膠體，也可以保留在聚合物中任何可能的地方而不至于帶來麻煩。Emulsify, 乳化， Protective colloid, 保

14、護(hù)膠體。 Dispersions, as obtained by emulsion polymerization, can be coagulated or precipitated by the addition of electrolytes. Dispersion, 分散相，分散體系. Emulsion polymerization, 乳液聚合Coagulate, 凝結(jié). Electrolyte, 電解質(zhì)從乳液聚合得到的分散相可以通過添加電解質(zhì)而凝結(jié)或沉淀。Formic acid or sodium chloride is used most often. 甲酸或氯化鈉是最常用的電解質(zhì)。

15、The purification effectiveness of such a precipitation is rather incomplete, because the emulsifying agents are not completely removed; their content is only lowered. 這樣一個(gè)沉淀的提純效果是相當(dāng)不完全的，因?yàn)楸M管含量很低，乳化劑沒有完全被去除掉。However, even this is often sufficient to make precipitation of the polymer dispersion prefer

16、able to a direct drying on the mill or by spraying. Mill, 研磨機(jī)。 Spray, 噴霧然而，在研磨機(jī)上或噴霧方式直接干燥是經(jīng)常使用的聚合物分散相沉淀的制備方法。Polymer dispersions can also often be precipitated and purified by pouring them into methanol, by adding methanol, or by cooling the dispersion in some kind of a cooling mixture (-20 to -40).

17、聚合物分散相也經(jīng)常被沉淀或提純，如把高分子倒入到甲醇里，向高分子分散相添加甲醇，或通過用某種冷卻混合物（20-40度）冷卻分散相的方法。Of special importance is the purification of natural macromolecular compounds. 天然高分子化合物的提純是很重要的。These usually contain low molecular weight materials or other macromolecular compounds, and in some cases there is even a chemical combi

18、nation between the different compounds; for example, cellulose with lignin (in wood), or pectins ( in flax). 天然高分子通常包含低分子量材料或其他大分子化合物，而且在一些情況下，甚至在不同的化合物之間存在化學(xué)結(jié)合，如纖維素和木質(zhì)素（在木材里），或果膠（在亞麻纖維）。Cellulose, 纖維素Lignin，木質(zhì)素Pectin，果膠Flax，亞麻纖維In such cases it is justified to consider this combination as a new mac

19、romolecular substance. 在這個(gè)情況下，證實(shí)了這個(gè)結(jié)合產(chǎn)生了新的高分子物質(zhì)。Since it is usually not possible to isolate the macromolecules without chemical reaction and therefore usually one does not obtain them in an unchanged form, one does not give these compounds a proper name but calls them propopectin or protocellulose,

20、etc. Isolate, 隔離，析出，絕緣Propopectin, 原果膠Protocellulose,原纖維素因?yàn)闆]有化學(xué)反應(yīng)而析出高分子通常是不可能的，因此不改變形式的大分子是不可能得到的。我們不能給這些化合物一個(gè)恰當(dāng)?shù)拿郑皇欠Q它們?yōu)樵z或原纖維素等。the isolation of the pure compounds (pectin or cellulose) can be brought about by acid, or alkaline, or enzymatic hydrolysis (wood pulp by the sulfite process or by al

21、kali treatment).Bring about, 帶來，造成Pulp，漿狀物，wood pulp,木漿Sulfite，亞硫酸鹽通過酸，或強(qiáng)堿，或酶催化水解（木漿被亞硫酸鹽化過程，或被堿處理），可以讓純的化合物析出。Low molecular weight impurities (for example, residues or solvents or monomers) can usually be removed by heating in vacuum. Residue, 殘余物低分子量雜質(zhì)（如殘留物或溶劑或單體）通?？梢酝ㄟ^真空加熱的方法去除掉。Since one cannot

22、mix the molten polymer in some kind of a stirred vessel, (because of its high viscosity) one has to use special techniques and apparatuses, depending on the polymer. Stir, 移動，搖動，攪拌，激動Vessel, 容器因?yàn)槲覀儾荒芑旌显谀撤N攪拌容器中的熔融高分子，（因?yàn)樗母哒扯龋?，根?jù)高分子的不同，我們必須使用特殊的技術(shù)和設(shè)備。Macromolecular substances with a high softening po

23、int (over 100) can often be dried in the form of a powder or in granules. Granule, 顆粒，細(xì)粒具有高軟化點(diǎn)（超過100度）的高分子物質(zhì)常?？梢栽诜勰┗蚣?xì)粒狀態(tài)下進(jìn)行干燥。This is done by spreading them out in a vacuum oven and heating them usually with an infrared lamp. 我們可以把這些高分子物質(zhì)散播在真空爐中而且用紅外燈加熱。If the materials which is to be removed is vol

24、atile only at a temperature which it is higher than the softening point of the polymer, one can use certain extruders in which it is possible to apply vacuum at certain places along the machine and thereby remove the solvent. 如果該可去除的材料僅僅在高于聚合物軟化點(diǎn)以上的溫度下是揮發(fā)性的，我們可以使用某種擠出機(jī)，沿著該機(jī)器的某個(gè)地方可以應(yīng)用真空而去除溶劑。In such

25、vacuum extruders (welding machine) one can treat thermoplastic materials, such as polystyrene or polymethylmethacrylate (at 180 to 250). 用這樣的真空擠出機(jī)（焊接機(jī)），我們可以處理如聚苯乙烯或聚甲基丙烯酸甲酯這樣的熱塑性材料As a result of constant renewing of surface by the milling process in the vacuum-zones of the extruder, a very rapid and

26、 effective removal of the volatile compounds is obtained. Renew, 修復(fù)，重復(fù)，更新. Zone,區(qū)，帶，層在擠出機(jī)真空區(qū)用研磨工藝對聚合物進(jìn)行恒定的表面更新，我們就可以非常迅速而有效地去除揮發(fā)性化合物。Great care must be taken in the isolation of proteins from their aqueous solutions because they usually degenerate even at rather low temperatures. 蛋白質(zhì)從水溶液中析出需要特色小心，因?yàn)?/p>

27、蛋白質(zhì)即使在相當(dāng)?shù)偷臏囟认乱渤３０l(fā)生退化。Such solutions can often be concentrated by freeze-drying. 這樣的溶液常常用冷凍干燥的方法得到濃縮。This is done by bringing the surface of the solution in close contact with a cold condenser and applying high vacuum to the entire apparatus so that the water from the solution forms as ice on the con

28、denser. 通過讓溶液表面與冷凝器接觸，并把高真空用于整個(gè)設(shè)備的方法，使水從溶液變成冰。The solution to be concentrated can be in a frozen state during this process.在這個(gè)過程中，被濃縮的溶液可以處于冷凍狀態(tài)。Low molecular weight impurities which are not volatile, such as inorganic salts in natural products, can be removed by dialysis, or eletrodialysis, of the

29、polymer solution.不具有揮發(fā)性的低分子量雜質(zhì)，如天然產(chǎn)品中的無機(jī)鹽可以通過滲析法，電滲析法從高分子溶液中去除。Dialysis,滲析 The separation of different macromolecular compounds which are present in the mixture is particularly difficult. 在混合物中的不同高分子的分離是相當(dāng)困難的。This is especially so if the solubility is the same, so that extraction or precipitation does not bring about a separation. 如果特殊到溶解性相同，那么用萃取或沉淀方法不能分離它們。This problem is often encountered in protein chemistry. 在蛋白質(zhì)化學(xué)中，這個(gè)難題是經(jīng)常遇到的。Since the protein molecules are usually present in the solution in the form of ions, one can use the difference in their rate of diffusion in an electric f