OTS: 60-11,775 JPRS: 2855

26 June 1960

Reproduced From

Best Available Copy

NEW CHINA'S PROGRESS IN THE

CHEMISTRY AND CHEMICAL ENGINEERING

OF H IGH POLYMERS

- COMMUNIST CHINA -

By Ch'lien Pao-kung

IMSTPBUfION ETATEYMNhT AApiyan'I' fox~ rV.Ma u"M

Distributed by:

OFFICE OF TECHNICAL SERVICESU. S. DEPARTMENT OF COMMERCE

WASHINGTON 25, D. C.

--- -----------------------------------------------------U. S. JOINT PUBLICATIONS RESEARCH SERVICE

205 EAST 42nd STREET, SUITE 300

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JPRS: 2855

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NEW CHINA'S PROGRESS IN THECHEMISTRY AND CHEMICAL ENGINEERING

OF HIGH POLYMERS*

C7This is a full translation of an article by

Ch'ien Pao-kung appearing in .Ko-~hsueh Tlun - ao(Scientia), No 20, 26 October 1959, page';s 6732_

In view of the fact that this is an era characterizedby the use of materials and atomic energy of highpolymers, the second half of the twentieth century hasbeen appropriately termed a Joint era of higla polymersand atomic energy,

The world's gross annual production capacity ofrubber, plastics and synthetic high polymer fibersas of now is placed at approximately 10 million tons,or over twice the volume of production of nonferrousmetals. This will be increased to 25-30 million tonsin 15-20 years. .During the past thirty years, thisnewly developed synthetic chemistry of high polymershad achieved enormous growth and spectacular success,giving sure guidance to the creation and utilization ofchemical compounds of high polymers, A modern andstrict theoretical treatment of high polymers has beencreated, dealing with the reaction processes oftheir formation and dissociation, and with theirstructure and properties.

* This article is a resume compiled and written byWang Pao-jen. Ho Ping-lin, Wu HsLang-lung,Ou-yang Chun, Ch'ien Jen-yuan, Ch-ien Pao-kungand others who have contributed to the researchon chemistry of high polymer during the pastdecade. The manuscript when completed was readby Wang Pao-jen, T'ang H'ao-ch~ing, Ch'ienJen-yuan and others, to whom thanks are due.

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Because of the demand for rubber, plastics,chemical fibers and resins and other high polymermaterials for sooialist reconstruction in China,research work on the chemistry of high polymersexpanded after Liberation under the party's leadershipand support and has reached maturity in the tenyears following the founding of the regime. BeforeLiberation this branch of science was a "bland."t

The principal task of the government isto produce in quantity such high polymer materialsas are being manufactured by the advanced worldthrough China's own high polymer chemical engineeringand chemical research, and on the basis of China'spractical needs, resource characteristics, scientificlevel, and technological conditions, Miluch workincluding laboratory research and intermediate factorytesting has been done during the past decade onthe compounding and polymerization of individualhigh polymer materials and the processing and changingof properties of natural high polymer materials.Simultaneously, theoretical research on the structureof related reactions and the texture and properties ofhigh polymers was conducted with appropriate care.According to incomplete statistics now available,about 500 research reports and treatises were compiledand written during the past decade. Two-fifths of thesestudies dealt with the practical phase while one-fifthwas devoted to theoretical exposition.

All in all, the chemistry of high polymers hasprogressed from nil to notable growth in New Chinaduring the past decade; it is an accomplished fact,while an adequate contribution has been made to thetraining of cadres, thereby laying the foundation forfurther study on the chemical theory and practiceof high polymerization.

I. Natural Rubber and Synthetic Rubber

Rubber is indispensable to modern industryand standards of living, and its elasticity isirreplaceable. It is principally used for themanufacture of motor vehicle and airplane tires,transmission and conveyor belting, electric cordand cable and various types of technical accessoriesas well as daily necessities and sanitary articles.

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World production of natural rubber is estimatedat two million tons per annum, In two decades theproduction of synthetic rubber has almost overtaken thatof natural rubber. The latter is applied to generaluse while the former is also used for specializedpurposes. The prospects for developing both natural andsynthetic rubber to meet natural and industrialrequirements in China are bright,

Natural rubber. Investigations after Liberationrevealed that China is richly endowed with rubberresources -- principally "san-yeh-shu" rubber Brazilrubber7, "hsiang-chiao-tslao" rubber, "tu-chung" rubber/Gutta-percha7, "hsiang-chiao-t'eng" rubber L'uappingsfrom ratta_/, etc. The chemical composition,molecular weight and physical and mechanicalproperties of these principal varieties were analyzed,examined and studied accordingly, and it wasestablished that natural rubber produced in China(san-yeh-shu rubber) resembled that of Ceylon inchemcoal composition and molecular weight and that asimilari`ty also existed between the two in technical,physical and mechanical propertLes. By comparisonthe Chinese variety is higher in primaryplasticity.

In view of this characteristic, research onplasticity and plastic reduction with reference to therelationship between plasticity and molecular weightand changes in molecular weight and distribution duringreduction was conducted, At the same time laboratoryteotng on mixed reduction was performed.

Vulcanization and aging of natural rubber wasexamined in relation to tire production withemphasis on the measurement of vulcanization and agingand the problem of coke combustion and vulcanizationin relation to the natural rubber produced inChina.

Manufacturing rubber goods directly with latexfrom natural rubber is an importan;t problem confrontingthe modern rubber industry. In this connnection,research projects on latex transformation,concentration, reductIon, compounding, preparation forsemi-vulcanized and vulcanized latex, macerated filmlatex production, "latticework" macerated film latexprod-action, e'o., were preliminarily and successfullyconsummated,

During the past decade, research on natural

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rubber production in China was well begun and a definitefoundation was laid. Henceforth, investigation onnatural rubber resources, especially its Chinesecharacteristics, should be made with increasing effort.Such problems as plastic and mixed reduction,vulcanization and the aging process, grafting andquality conversion of natural rubber, the utilization ofnatural latex and the manufacture of special rubbergoods should be examined in the light of both theoryand practice so that the technology of rubber productionmay be systematically established in China. Long-rangeresearch on the texture of caoutchouc, if conditionspermit, should be made, This problem has yet to besolved by scientists.

Synthetic rubber, Synthetic rubber is onethe important accomplishments and development landmarksin the entire field of modern high polymer chemistry.It has general, exclusive and specialized uses accordingto its properties. The work was begun immediately afterLiberation. During this stage, the task like that forthe development of synthetic materials of highpolymers, was to manufacture such products as werealready produced in quantity abroad. The emphasis was,therefore, placed on reaction factors necessary to thesolution of industrial chemical processes particularlythose from basic materials to isolated syntheses andfrom isolated syntheses to the production of highpolymers.

Generally speaking, ethyl benzene rubber ismainly used for the production of synthetic rubber.After Liberation, stress was placed on the study ofbutadiene and the two processes for its synthesis,/the first beinj the synthetic catalytic derivationof butadien from alcohol, and the second the syntheticcatalysis of butane-butene in petroleum diotillationoAs to polymerization, research was concentrated on theformula for polymerizing an improved butadiene-styrenelatex with applications in modernr industry withsome improvement. In addition, preliminary research onthe selection of oils for the making of ethylebenzene rubber for lubrication use was conducted.

Butadiene serves directly as raw material forthe making of many types of synthetic rubber."Ting-pli"t rubber, capable of resisting heat andoil, is a new line being developed in China forgeneral and special uses, and through chemical

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conversion new properties may be evolved. Itsdevelopment is being continued.

By means of directed polymerization, thetexture of butadiene may be so regulated as toform polymerized butadiene of improved elasticity andlower molecular count; but --when it is mechanicallygrafted to ethylene-propylene polymers of lowerelasticity and higher molecular count, an adjustmentmay be made at will for the desired elasticityand molecular count. Its potential is bound to playan important role in the future growth of syntheticrubber for general application, This research workis being pursued in China,

By the method of directed polymerizationmentioned above, isoprene may be syntheticallypolymerized to present a structure exactly similarto that of "synthetic natural rubber." When itsunit production cost is lowered, its growth willbe enormous,

Research on chlorinated latex for the manufactureof special rubber was also undertaken in Chinawith adequate progress. However, little work was doneconcerning chlor-prene rubber in respect to isolatedpolymers and changes in the properties of chlorinatedlatex. New lines should henceforth be developed byexploratory testing.

Polymerized sulfonated rubber is highly oil-resistant. In the past, research on A, B, and Fgrades of polymerized sulfonated rubber was undertakenwith emphasis on their preparation in the liquid state.A mixing of this varioty with diolefInes couldincrease the latter's oil-resistance, Testing alsoproved that polymerized, sulfonated chlotinated rubberwas superior to the butyl-nitriles type in bothoil-resistance and strength.

As to special varieties, research on siliconrubber was done with definite success and preliminarywork on flucrine rubber was also started in recentyears.

Some gaps remain to be filled in the productionof synthetic rubber. For example, abrasion-resistingbutyl-carboxyl and amino-ester rubber and isobutylrubber of low porosity as well as problems of vulcanizat-ion and aging remain to be examinedo

In short, a proper foundation has been laid forthe conduct of research on synthetic rubber. In theintepest of consolidating the production of synthetic

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rubber, we should, apart from oontinuing to examineethyl-benzene and chlorinated rubber for massproduction, devote our study to new-typerubbers such as diolefines, "ting-p'i" and butyl-carboxyl types, particularly the directionallypolymerized synthetic rubber, Work on exclusiveand special rubber should continue to be developed.Exploratory steps for new types should be immediatelyundertaken with emphasis on synthetic rubber ofdesignated property or properties. These steps may alsobe taken on a long-term basis,

II. Plastic Materials and Synthetic Resin

Synthetic plastics and resins vary greatly anddiffer in their properties. Their applications arebroad, extending to the manufacture of motorvehicles, airplanes, and machines, and to theelectrical, construction and ship-building industriesas well as the chemical anf foods industries, where theyare used as structural, insulating, lhemical engineeringand decorative materials.

World production volume, of which highpolymer materials account for much the greatestproportion, now exceeds 4 million tons per annum, ortwo times the figure of five years ago,

Sunthetic plastics and resisn may be classifiedaccording to the method of polymerization as polymer-added and polymer-condensed, in addition to a typeknown as ion exchange resin. Work was begun soonafter Liberation but there was no important developmentuntil two or three years ago,

Polv mer-added Plastic Material and Resin. Underthis heading, the main variety is isolated highpolymer ethylene, the symbol of the modern plasticsindustry.

Mainly as a result of improved methods ofpolymerization, high polymer ethylene in recent yearshas had the most rapid increase in volume of productionamong all plastic materials. In the wake of the develop-ment of high pressure polymerization methods came thedevelopment of intermediate and normal pressuremethods. Low pressure, metallic, organic, and catalytic

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polymerization methods were first examined whileresearch on the other two methods had begun,The polymerization of propylene (polymerized propyleneis used for the manufacture of synthetic high polymerfibers) was brought about by the application of thecatalytic polymerization method together withmetallic oxides (the intermediate pressure method),Also, the radioactivity of atomic (reaction) andultra-violet rays were utilized for the preparationof polymerized ethylene. This method for changingthe properties of high polymer materials is worthyof development.

In the past, a series of studies was made of theparparation of high-use vinyl chloride by theisolated synthetic polymerization method with fairlysatisfactory results. The flotation and emulsionpolymerization methods were studied in somewhatgreater detail. In addition, research on vinylperchlorate and meta dichloro-eti'ylene was conducted.Joint polymerization of isolated materials such as vinylperchlorate resin, meta dichloro-ethylene, and others.will be given greater emphasis,

Emphasis was placed on studies of the isolatedsynthetic phase of polymerized styrene, and thedehydrogen reaction of ethyl benzene was observed withgreat care,, The method of radioactive polymerizationthrough the use of atomic energy and the directedpolymerization method with metallic and organicmaterials were also explored. The radioactive anddirected polymerization methods will be developedin line with broad studies on all types of isolatedethylene.

Among polymer-added ethylene materialsexamined during the past decade was methyl acrylate,used for the preparation of organic glass. Theisolated synthetic method was also improved. Theeffect of a slight amount of oxygen on the accelerationof isolated polymerization and the effect of anexcessive amount of oxygen on the i.etardationof polymerization of' methyl acrylate and otheresters was observed to affect the speed of polymerization,and when compounding of acrylic acid or starinic esterof methyl-acrylic acid was explored, the polymer wasobserved to have acquired new properties,

Vinyl acetate, ethylene alcohol, acetal andother materials of high polymer may be used for the

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manufacture of plastics material, paint, adhesive andfibers, on which a series of research projects had beenconducted in the past, Polymerized ethylene alcoholand condeneed butyl aldehyde used for the productionof adhesive and polymerized ethylene alcohol andcondensed methyl alcohol employed for the preparationof synthetic fibers were more carefully studied,

Also, plastic materials containing fluorineand possessing high temperature and corrosion resistance,N-vinyl used as substitute for plasma, polymerizedvinylite pyridine used as an ion-exchange agent, andpolymerized methyl alcohol with possibility forpotential development were examined.

In the field of ethylene research• there aregaps to be filled. Some principal forms of derivedand homologous products mentioned above includingvinylite ether and isobutene employed for ionicpolymerization remain to be studied,

It is evident from the dscription given abovethat the principal varieties of polymer-added ethylenewere largely, if not completely, examined during thelast few years and that a definite foundation has beenlaid. In view of the fact that most varieties of isolatedethylene were involved in the production scheme of heavy,organic synthetic and petroleum industries and that manyof them were concurrently regarded as raw materialsfor the preparation of synthetic rubber and fibers,the development of all these products should beGiven joint consideration. Because of their wideindustrial application, emphasis should be placed onthe growth of polymerized ethylene and vinyl chloride.At the same time, future research work should bedirected toward the creation of new properties, newpolymerization and property conver3ion methods and, moreparticularly, the development of high polymerethylene materials with greater heat resista:.-ceo

Condensed Polymeraizzed F1JasC -Materialsand Resins. Re7, •ino and pla ',materials thatwere obtained by the method of 3ondensation and .polymerization, ranging from older aldehyde phenateplastics to more recent reinforced plastic materials,were generally examined during past few years.

Aldehyde phenate resins used for thepreparation of plastic materials, paint and adhesivesare not produced in comparatively large quantities in

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China. As a result of a few years' effort, it has beenpossible to brcaden the scope of production from simpleelectrical appliances and daily necessities to acid-resisting aldehyde phenate plastics containers,colloids, etc., for chemical induetrial application,friction-resistant brake-lining and adhesives for motorvehicles, silent gears and axles for machinery,aldehyde phenate paint and plyboard for industrial use,etc. We should continue to solve these problemsand to increase the number of varieties in order tobroaden their scope of application°, It is imperativethat resin or rubber be polymerized by the graftingmethod so as to create high-temperature-resistantand corrosion-resistant plastic materials of highstrength as a partial substitute for nonferrousmetals

The prospect for the development of furfuralresin and plastic materials is considered goodin view of the fact that furfural may be made availablein China from her bounteous agricultural production.The problem of processing furfural was resolvedwith great effort only recently, The preparationof furfural synthetic resin was related to the problemof catalysis, the solution of which facilitatedthe improvement of techniques in the processing ofplastic materials. Again, there was the developmentin recent years of furfural-acetone resin. In solidform, its mechanical properties and its chemicalstability surpassed aldehyde phenate plastic,materials in quality, it is worthy of developmentin China.

It was a general practice to treat urea-formaldehyde resin by the low temperature method but whenthe high temperature method was adopted, productionprocedure was simplified. Highly heated urea-formaldehydefoam plastics with' very low specific gravity was foundin a trial experiment to have prevented urea-formaldehydeemission plastics material through evaporation.Urea-formaldehyde plastics material would henceforthbe tested with solid fuel. Little research was doneon paraformaldehyde which is similar in typeto urea-formaldehyde resin. With satisfactoryprocurement of raw suited to the development ofplastics goods in China with extensive applicationsin light and heavy industry, it would be possibleto manufacture low-priced high-quality dailynecessities.

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During past two years, studies on how to reinforceplastics material with unsaturated and cyclicoxygen resin were undertaken, Reinforced plasticsnow play a very important role in -the growth of theplastics industry. Their strength already approaches thatof hard steel-aluminum alloy, They are low inspecific gravity, corrosion-resistant, elastic, goodfor insulation, capable of being processed into articlesof odd shapes and suited to the production of automobileradiators, shiphulls, machinery, oil tanks, piping,etc. These plastics should be regarded in China as akey-point for development. Our main problem lies inthe acquisition of resources for the manufacture ofreinforced plastic materials (fiber-glass andother fibers of hi-gh tensile strength) and resincompounds. In addition there is the problem ofadhesion. Cyclic oxygen resin, which is an adhesivagent, should therefore be developed,

Also, hydroxyl-carboxylic acidic resin usedfor the manufacture of synthetic paint may beextracted from a phenate compound found in Chinese paintfor the manufacture of corrosion-iesistant paint and wood-oil plastic material. In the past, -esearch onthis problem was especially conducted to ascertain thecomposition of Chinese paint and the structure of itsphenol content, The paint industry is considered animportant branch of the high polymer industry. How toutilize Chinese raw materials and resin compoundsfor the manufacture of high-quality paint now loomsas an important problem for research.

Finally, the study of silicon materials ofhigh polymer should be dealt with, Main work inrecent years was confined to the examination of isolatedcompounds involving the improvemeut of the traditionalmethod of preparing polymerized silica paraffins inisolated formL, the isolated aspect of chemical properties,the production of silicon oil, silicon resin, siliconpaint, silicon rubber and other materials of highpolymer. Apart from the silica types of high polymermentioned above, exploratory work was done onsilicon-silicon type, silicon-car-bon-silLcon-oxygencompounds of high po:lymer, etc.

Because of their wide application in the Chinesenational economy and because of the availab*lity ofraw materials, adequate foundation has already beenlaid for the further study of the condensed, polymerizedresins and plastics mentioned above. For these

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studies, the stress will be placed on reinforced andfoam plastics, silicon materials of high polymer, newlines of condensed, polymerized production and theirdevelopment and creation.

Ion-exchange resin0 Ion-exchange resin, the"tooilless equipmentr iown for its broadapplications in the chemical industry and other relateddepartments, employed as it is for the purification ofwater, dissociation of metals and rare elements,dissociation and purification of' antibiotics and othervaluable chemical products.

It is a poly-added or poly-condensed product.Being an acid or alkali radical of high polymer, it isclassifiable either as a positive or negative ion.

The earliest study in our research on ion-exchangeresin was associated with sulfonated coal used industrial-ly for the purification of water. Subsequent researchwas related to studies on sulfo'iyl aldehyde phenateresin and sulfonyl stryrene phosphate resin -- twoeffective acid-type exchange resins. Also, stryrenephosphate resin -- a medium acid-type exchange resin --was experimentally manufactured, A wrveah acid-typepositive ion-exchange resin was developed along with theextraction of streptomycin (an antibiotic), vegetablealkaloid and other bicohemical products. Many linesof high-quality products were produced, and an insolubletype of exchange resin was developed,

In connection with negative ion-exchange resin,research on amino salts-- a strong alkali-type exchangeresin of high quality -- was iundertakeno In addition, aseries of weak alkali-type exchange resins was compounded.These negative exchange resins were used to purifywater, to eliminate slight quantitites of carbon dioxide,to extract uranium, and to dissociate natural products.

Apart from the uses just mentioned, ion-exchangeresin is extensively used for chemical analysis,Positive-ion-negative-ion resin, by virtue of its re-association propeiity, is utilizeii. to purify seawater,

The demand for ion-exchailge resin is bound torise as industries are developed in China, In the past,a sound foundation was laid to facilitate the develop-ment of new types of ion resin such as highly selective,heat-resistant, radioactive ion-excbange agents, ion-exchange film, paper or liquid resin, electron-exchangeresin, optically active resin, etc. Theories on theelectrolytic properties of high polymers are worthy of

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research.

III. Artificial Fibers and Synthetic Fibers

Chemical fibers are being broadly developed astextiles, cords, thin films, fish-nets and substitutesfor wool, silk and hides.

Chemical fibers consist of two main varieties:artificial fiber and synthetic fiber. The volume ofworld production already exceeds 3 million tons perannum, or one-third of the production volume of naturalfibers (cotton, wool and silk). Artificial'fibers andsynthetic fibers are currently produced In a ratio of9 to 1 but the development of the latter variety isproceeding at an accelerated pace.

Provided as she is with the requisite resourceand performance factors, China will witness a rapiddevelopment in the production of artificial and syntheticfibers.

Artificial fibers. Artificial fiber orviscose is artificial silk developed from natural fibersby the adhesive method. Fibers from coniferous woods aretraditionally regarded by the world as raw materials forthe production of viscose, As the resource situationin China is different, it is necessary to consider theutilization of fibers other than wood fibers,

After careful study and intermedi-ate testing, itwas found possible to substitute bagasse for coniferouswood fibers as raw material for the mamulfacture ofviscose. During the past two years, experiments havebeen performed on a large scale to determine whethergrass fibers such as reeds, wheat stalks, rice straw,bamboo, kaoliang, and cotton stalks, etc., could be usedfor the production of artificial fibers or viscose.Altogether, over 20 varieties of plants vere tested.

Adequate methods and conditions were establishedfor the dissociation and refinement of grass fibers,Vheir viscosity, polymerizationi, energy of reaction,ultra-molecule structure, chemical. composition, etc.,were examined with varying degrees of intensity° Researchon the simplification of viscose processing and preparat-ory steps for the production of reinforced artificialsilk undertaken with preliminary success.

In addition to research on grass fibers, the de-rivatives of ester and ether and changes in the propert-

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ies of other natural fibers were examined, too.The natural cause for fiber chemistry in China

seemed tO lie in the utilization of her unlimited grassfiber resources. Achievements in the modern chemistryof high polymers will be utilized to improve the qualityof artificial fiber and to change the properties of natur-al fibers as well as to examine to the structure andenergy of reaction fo fiber in general.

Sunthetic fibers. Synthetic fibers knownfor their fine quality have developed greatly during thepast two decades. They may be classified under the twocategories of polymer-added and polymer-condensed fibersaccording to the method of polymerization, the lattervariety being the more important. They were examinedin China recently with varying degrees of intensity.

As to polymer-added products, the prospect forthe growth of polymerized propylene fiber seems to bebright because its cost of prodnction is as low as thatof cotton fiber and also because it is comparable tosynthetic fiber in quality. The problem is beingstudied in China with particular reference to the improve-ment of the directed polymeriZation method0

Polymerized propylene fiber (orlon), aging-resistant and similar to wool 'in quality, is being tested6A special solvent (dimethylamine) was heeded for drawingfiber, To avoid using this solvent, two measures wereconsidered: polymerization could be performed in saltsolution and acrylonitrile and vinyl chloride could bepolymerized on an isolated basis. The experiment wasconducted with preliminary success but fufther researchis necessary,

The compounding of polynmerized ethylene alcohol andmethyl aioohol fiber /w ei-ni-lu;/ with polymerized vinylchloride by the addition of carobide is being tested. Theproperties of these two types of fibers, especiallythose of polymerized vinyl chloride, remain to be examin-ed. Therefore, improvements should be sought in themethod of polymerization and fiber drawing,

Regarding condensed, poiymerized products, nylonfibers play a dominant role among synthetic fibers, Inrecent years, much research work has been done in Chinato perfect the compounding of nylon fibers 6,9,11,66,96, 1010, etc.

The source of isolated elements and the method ofcompounding were emphasized. The method of polymerizingamino fiber was improved. From castor oil were extracted

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polymerized amines 9 and 11 for the compounding of aminopelargonic acid, and from furfural was drawn polymerizedamine 66 for the compounding of butane dicarboxylic acidand hexylamine. While basic materials -- castor oil andfurfural -- may readily be obtained from China'sagricultural resources, their synthetis is nonethelesscomplicated, and simplification is expected,

The condensation of polymerized products, especial-ly the reaction from hexylamine, was examined with care*An improved surface condensation method for the prepara-tion of polymerized amine 66 was considered. Thesynthesis of polymerized ester fiber was given prelimina-ry study. The mechanism of this polymerized esterreaction was studied in relation to the general structureof polymerized ester reactions,

In the case of condensed, polymerized products,there are gaps to be filled. Among recently developedsynthetic high polymer fibers may be listed polymerizedamino-ester, polymerized resin carbonate, anhydride,etc. Fiber-drawing is especially important in the studyof synthetic fibers. The development of this technique,involving high polymer physics, is only at the initialstage.

All in all, the study of synthetic fibers hasbegun in China. The development of fibers and theclarification of conditions under which the study ofa particular variety may become dominant, as is the casewith the other types of synthetic high polymer products,can only be the result of intensive research, Ourexamination of synthetic fibers reveals that the weaklink seems to be the problem of surface condensationand fiber drawing; this problem should be examined fromboth the theoretical and the practical standpoints. Theexploratory work for the discovery of new types of syn-thetic fibers should be conducted on the basis of whathas already been accomplished.

IV. Reaction Mechan.sm and Dynamics

The mechanism of a reaction of high polymerformation and dissociation is a dominant scientificproblem in the study of high polymer chemistry. Itconcerns procedures of preparation, processing, propertyconversion and operation, which must be examined fromboth the theoretical and the practical standpoints.Research on these problems has been conducted throughout

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the world. While work in China has begun only recently,the Chinese contribution to the solution of sometheoretical problems, especially the problem of themechanism of condensation reactions and some aspects ofdynamics, is obvious.

Reaction of. o, er addition• This reactionmay be considered as a high polymer reaction to thepolymerization of isolated vinyl, and has been proved tobe a chain-reaction. In analyzing the dynamic aspect ofthis reaction, Bodenstein's hypothesis of stability wasoften taken for granted, Its validity was questionedbecause the hypothesis did not stand the test of strictmathematical analysis. When the spontaneous reactionto polymer addition was examined through dynamic analysis,the reasonableness of his hypothesis was proved, It ishere perfectly applicable.

In practice, emulsion polymerization is a methodwidely adopted for the preparation of synthetic rubbwrand plastics. Whether reaction to polymerization occursat the absorption layer of the smulsicn or within theemulsion itself during the process remains debatablesince the evidence permits both interpretations. Carefulexamination of the procedure for emulsion polymerizationof styrene showed that the speed of polymerization wasdetermined by activity at the surface area of the emul-sion, suggesting that Medvedev's contention that react-ion to emulsion polymerization occurred at the absorptionlayer was more likely to be the case,

Reaction of condensation, This is anotherimportant reaction in the preparation of chemical compoundsof high polymer, It was generally believed that thecondensation-dissociaticn equilibrium that occurred duringreaction would affect the distribution of the molecularweights of condensed products. But when a typical caseof condensation reaction was analyzed from the standpointof dynamics, the results demonstrated that, grantingthat dissociation reaction was present, it was stillpossible for the molecular weigt of the condensedproducts to be distributed according to Flory's law.

But in the course of condensation reaction,especially toward the close of amino-compound polymeriza-tion, adhesiveness seemed to increase in the substance,Under this circumstance, smaller molecules were morelikely to expand and dissociate while larger moleculeswere provided with more numerous dissociation bonds.

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These two types of molecules were likely to undergochain exchange reaction, causing medium-size moleculesto be formed and their molecular weight to be concentratedin such a manner as to contradict Flory's theory ofdistribution. This phenomenon was clearly visible in theprocessing of hexylamine compounds.

The reaction of polymerized ester is typical ofcondensation reactions. The process rate of its react-ion has, however, elicited much discussion. On the basisof practical results and dynamic inference, it was feltthat the reaction to simple ester activity seemed toagree with the catalytic process of hydrogen ion, Thetheory expounded by scholars that the binary acidmolecule was a catalytic agent in itself and that react-ion to polymerized ester was but a reaction to doublemolecular activity was not entirely borne out by thefacts. At the same time, the hypothesis that the energyof reaction was not connected with isolated chainactivity -- a basic hypothesis for the analysis ofcondensation dynamics -- was verified.

The structure of hydrogen ion reaction was de-monstrated by studies on the dynamics of three-dirgction-al polymerized ester reactiomo The gel activity of three-directional condensation reaction was again demonstratedin practice as well as in theory.

In the case of lactams, the mechanism of reactionwas complicated because lactams are a cyclo-isolation.The mechanism of its reaction is being examined throughoutthe world. Chinese scholars felt that in the open-cycle condensation mechanism were included such processesas polymer-adding activity, increasing condensation, andthe chain-exchange equilibrium reactions It was believedthat the double-ion structure resulted from polymer-adding activity and that the distribution of molecularweight was influenced by chain-exchange,

Also, the dynamic aspect of the condensation react-ion of dimethyldihydroxy-silico-paraffin was examined.It was proved that a definite ratio was maintainedbetween an isolatulon and a double polymer and thatthe latter was polymerized on the one hand while it wasconverted into an isolation on the other.

Radioactive interchange, Statistical theoryon radioactive interchange has developed with the advance-ment of radioactive interchange of high polymers.Charlesby's erroneous theory of solubility was correctedby Chinese scholars who demonstrated the solubility of

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radioactive interchange products of high polymer such asethylene, etc,

The mechanism of the light sensitivity exchangereaction brought about by the effect of ultra-violetrays on ethylene had never been examined before, Aftersome preliminary research, it was felt that there was alinear relationship between the rate of interchange inthe light sensitivity exchange reaction and the logarithmof the time factor. This was probably due to the self-filter photo effect of photochemical products. A newpath was opened for the selection of a photo-stabilizingagent of high polymer,

China's research on the mechanism and dynamicsof high polymer during the past 3-5 years has beensummarized above, Though this research was not heavy,the results were satisfactory. We should henceforthconcentrate on newly discovered important reactions ofhigh polymer chemicals of such as directional polymeriza-tion, static radioactivity, surface condensation, mechani-cal polymer grafting, radioactive interchange, agingprocess, etc. In theory and in practice, this researchshould be of a systematic, penetrating and exploratorynature so that the mechanism of reactions may be clarif-ied and the scope of their applications widened, Thus,a method for the preparation of new-type high polymers mayalso be created,

V. The Structure and Properties of High Polymers

Because of their superior and varied physical-mechanical properties, materials of high polymer gain inan important manner significant increase in the scope oftheir applicability depends larGely on the structure ofchemical compounds of high polymer, Therefore, studieson their structure and properties and the relationshipbetween them have become the central theme in theexamination of chemical compounds of high polymer. Thesestudies have both theoretical and practical value andimportance, This research work has begun in China,and some contribution has been made to studies on endedge range of high polymers, their solubility, mole-cular weight, etc.

Structure of High Polymers. High polymersare characterized by long chain action. The short-rangeand long-range structure of the chain and the structural

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behavior at the time of dollection should be examined.Regarding short'range structure, the interior-

exterior double-bond and interior double-bond structureof ethylene polymer and rubber molecules exercise animportant influence on the properties of a polymer. Inconnection with the polymerization of butadiene, benzoyloxide was utilized to measure differences in the speedof its reaction on the interior-exterior double-bond,and infrared rays were employed to measure the ratio be-tween the interior double-bond and the reversedstructure. Here, polymerized ethylene compounds playedan important role in directioned polymerization. Withthe aid of infrared rays, the content of double-bondsin various types of vinyl from polymerized vinylitechains was-examined to observe changes in double-bondsduring interchange.

Regarding long-range structure, the fundamentalproblem lay in the determination of the geometric struc-ture of linear high polymer chains, In calculating theedge range L•mo-tuan chu-lij of a high polymer, scholarsin China advanced a hypothesis on the inner rotation ofcarbon-carbon chains to derive a general formula forequi-square end edge range and to establish the relationbetween equisquare radius and equi-square end edge range.It was also possible to compute the value of high polymerisoprene at equi-square end edge range under hightemperature. But this remained to be proved by furthertesting. As to laboratory evaluation of inner rotation/tstan-shu7, it was not necessary to depend on thecoupling method for computing the degree of polymerizat-ion and the nature of the solvent.

As to structural orde,r research began with theproblem of ascertaining the degree of crystallization inpartly crystallized polymers. Thus, thin films ofpolymerized vinylite were measured with the aid of infra-red rays to ascertain the extent of its crystallization.A working curve indicative of the relation between polymer-ized vinylite concentration and the degree of crystalli-zation was also obtained. Infrared bias rays wereutilized to examine the direction of distribution incrystallization area during the pulling period of vinyli-te polymerization. Also devices to measure expansionwere used to check the crystallization rate of naturalrubber, It was observed that under varying crystalliz-ation temperatures and heating circumstances, there werevarying formulas to describe the formation of crystals

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and their developmenti

Soluble Properties of H! Polymers, The formof a polymer in solution is a major factor in thedetermination of its solubility. The effect of its formon the viscosity of the solution is first indicated bythe development of side molecular chains. This sidechain development was demonstrated during research throughthe viscosity behavior of flexible high polymer chainsin solution. For example, the dependence of viscosityon the concentration in solution of polymerized ethylebenzene rubber heated from 500 to 50 was clearly evidenceof the side chain development of high polymers. Thiswas in contrast with the visible absence of such actionin the case of flotation-polymerized vtnyl chloride.

Non-Newton flow was shown in solution in whichhigh polymers were adequately polymerized, thus contribut-ing to the understanding of the flexibility of highpolymer chains. During researoh, the possibility ofreversion to Newton flow under low shearing speed shouldbe considered. The viscosity value of ethyl benzenerubber in toluene solution under low temperature wasdetermined with certainty, The osmosis of hishpolymer solution concentration and its dependent naturewere generally shown in "wei-li" form, the second "wei-li" coefficient depending on the molecular weight and theinfluence of diffusion. Regarding the influence ofsolution diffusion on coefficient, a preliminary conclus-ion was reached by the methyl acrylate mixed grading methodand the duplicate grading method. The quantitativemeasurement of this dependent relationship of the molecu-lar weight of the second "wei-li" coefficient remains tobe done.

Molecular Weight and Its Distribution, Themolecular weight of chemical compounds of high polymerdepends partly on their physical-mechanical propertiesand partly on the process of polymerization and thenature of the solution in which these chemical compoundsof high polymer are formed. Their molecular weight isnot uniform. Because of the problem of molecular weightdistribution, only a statistical average can be given.

Basic methods for the measurement of molecularweight of high polymers such as terminal chemical analysisby mathematical average, elevation of boiling point,reduction of freezing point, osmosis, re-average radiat-ion, average viscosity, etc., have been improved upon

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from time to time since the manufacture of the necessaryapparatus was begun in China. In this respect, thetechnique has already been mastered and is being extendedto other fields of research. As to the super-speedcentrifugal and precipitation methods, preliminary workhas been started.

Although the absolute value of molecular weightcannot be measured by the viscosity method, the simplici-ty of this method renders it easy to obtain the relativevalue of the molecular weight. in recent years thismethod has been widely used. Formulas have been given forthe viscosity and molecular weight o6 methyl acrylate,methyl acrylate palmitate? 500 and 5U polymerized sthylebenzene rubber, "ting-pfi., rubber, hexylamine, etc,Also, the molecular- weight of natural rubber andnitrocellulose have been investigated,

During the past few years, much has been achievedin improving the technique of measuring molecularweight. Examples include improvement in the terminalanalysis of amides, the development of osmosis meterglass melting and crystallization, the improvement ofradiation refraction tanks, and the designing of semi-micro viscose dilution meters and viscosity gaugesequipped wi'ith lightproof, anti-oxidation and over-filtration devices.

Regarding the distribution of molecular weight,ethyl benzene rubber, natural rubber, vinyl chloride,polymerized amides,etc., were studied and measured bygrading methods. By studying the mechanism of reactionsduring polymerization, changes in molecular weightdistribution have been observed,

Physical and Mechanical Properties. The appli-cations of chemical compounds of high polymer are determin-ed by their physical-mechanical properties -- e. g.,the elasticity of rubber, the plasticity of plastics, thestrength and insulating power of machinery, the textileand tensile strength of fibers, etc, Some work hasbeen done in China,

The thermo-mechanical behavior of high polymermaterials should first be examined in the light of theirusefulness under a wide range of temperature. Thisrule was applied to tests for increasing the plasticityof organic glass and also in connection with the problemof radiation and light sensitivity interchange of ethylene.This work may yet be extended.

The viscosity-elasticity of high polymer materials

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is of primary importance among their mechanical propert-ies. The viscosity-elasticity of natural rubber wasgiven a preliminary examination, and its flow characteris-tics were established to be non-Newton in type. Thecrystalizing cause for the conversion of viscous flowinto plastic flow was also observed, on the basis of whichthe relationship between viscosity itself and the molecu-lar weight was established.

Also, increase in the plasticity of ethyl benzenerubber through thermal oxidation was investigated. Therelationships between solubility and the vulcanizationtime of natural rubber and the solubility of "ting-p'i"rubber after treatment with amino-sats were studied,too.

The dielectric property of natural rubber, thetransparency of organic glass, the double refraction pro-perty of fibers, etc., were also examined°,

Research done in China during recent years inconnection with the structure and properties of high poly-mers has been mentioned above. The work was mainly con-cerned with high polymer physics, Regarding this branchof science, we must start from the beginning. Onlythrough the development of this science can we acquiredeep understanding of the structure and properties ofhigh polymers and the relationship between them,

VI. Future Prospects

High polymer chemical research was begun after Li-beration. During the past decade, and especially thelast three years, much work has been done. Measuredby its scope and speed of growth, this accomplishment wasundoubtedly important, It was, after all, an initialstage mainly devoted to the study and mastery of modernhigh polymer chemistry in order to establish a high poly-mer industry in China. Thus the foundation was laid forthe future development of high polymer chemistry inChina. It is a stage through which the development andestablishment of modern science in any country mustpass.

To relate these developments with the circumstancesprevailing in China and to develop China s potentialitiesin the whole area of high polymer chemistry, future re-search works as in other branches of science, shouldfollow party s line for the conduct of scientific resear-ch in the service of socialist reconstruction. This de-

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velopment is to come through close collaboration betweentheory and practice and the adoption of the policy of"walking on two legs."

In a nutshell, the basic task of high polymerchemistry is the solution of problems concerning thesynthesis of high polymer materials and their process-ing and application,* At this initial stage in thedevelopment of the high polymer chemical industry, thesynthesis, processing and application of "well-known"high polymer materials should be studied, mastered, anddeveloped while the "unknown" high polymer materialsshould be explored, opened up and developed. With thisin view, important scientific problems should be examin-ed in relation to national needs and production practices.The concrete problems that are worthy of research havealready been discussed,

(1) To provide for the establishment and develop-ment of high polymer industry in China against ascientific and technological 'background, we have alreadyprogressed at key points in the preparation of majortypes of high polymer materials that are being producedin quantity in the world, such as natural rubberbutylsynthetic rubber, ethylene and vinyl plastics and resins,reinforced plastics and ion-exchange resins, grass fibers,and butyl-amides synthetic fibers, This research shouldbe conducted with greater intensity so that a systematic,penetrating and overall research structure may be erect-ed on the foundation that has been la1d. It is importantthat we should master and improve the chemical industrialprocedure for the preparation of isolated synthetics andhigh polymer materials, Their quality should also becontrolled and elevated and new lines should be developedat the same time with the development of new methods anduses.

(2) The processing and application of materialsof high polymer employs a range of scient'fic techniques.Here lies the weakest link of research work in China. Thedevelopment of the Chinese high polymer industry will behindered unless this problem ,s resolved immediately.

* Reference: V. Akarrin, "Basic Problems of HighPolymer Chemistry" (appearing March 1959 in areport before the Eighth Congress of "Man-che-li-fult Chemical Association, translation appearingin "Kao-fen-tzu TVung-hsin" (High Polymer News),Vol. 3, No 4, 1959, page 175.

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Regarding the vulcanization of rubber, the processingand molding of plastics and the drawing and stretching ofchemical fibers, these techniques should be improved andbroadened on the existing foundation by comprehensivelyabsorbine modern methods and by conducting scientificresearch including research on processing equipment.

Concerning testing and inspection of the tech-nical properties of high polymer materials, nationalstandards should be set up in China without delay. Tomeet the requirements for the creation of new-type highpolymer materials, the problem of testing and inspect-ing small-model trial samples for processing should bestudied and solved as soon as possible.

In a vast territory like Ch!_na covering tropi-cal and frigid belts, it is especially important thatthe problem of aging in which the structure and pro-perties of high polymer materials are altered under thesustained influence of heat, oxygen, light, radiation,mechanical force and chemical and pharmaceutical agents,should be examined with a view to prolonging the life ofhigh polymer materials and leading to the creation ofaging-resistant high polymer materials.

(3) To meet the demands of modern industry and"peak" techniques, new-model high polymer materialsshould be created with the object of increasing theirheat stability without sacrificing their workingflexibility under the desired temperatures, theirmechanical properties, or their aging-resistant qualities.To fulfill this goal, we should start with isolated andhigh polymer chemical compounds by adopting new methodsof polymerization, property conversion and processing.It is now known that some cyclochain high polymers(benzene, alkyl anilines, etc,) and hetero-cyclic com-pounds of high polymer (ester carbonate, anhydride, highpolymer fluorine, high polymer silicon, etc,,) havesoftening temperatures and disintegration temperatures.It is possible under varying conditions to increase theheat stability of isoaated or high polymer chemicalcompounds by adopting directione6 polymerization, polymergrafting, radiation interchange, and pulling and stretch-ing methods, The scope of application of high polymermaterials may be widened by close examination of thebehavior of high polymer chemical compounds under hightemperature of through examination of thermo-chemical orthermomechanical behavior when heat and oxygen coexist,Also, the problem of processing and molding heat-resistant

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high polymer materials is even more worthy of examina-

tion, for otherwise these materials would have noapplications# Radioactive stability increases with theimprovement of the quality of high polymer materials --a development so important in relation to the peacefuluse of atomic energy. This would lead to the applicationof atomic energy to high polymer chemical activity asin radioactive polymerization, grafting and conver-sion of properties, Further development should be broughtabout in China so that the two eras of high polymers andatomic energy may truly be united.

(4) To create high polymer materials of specifiedbehavior is one of the basic tasks and objectives for thedevelopment of high polymer chemistry, This should beginwith entirely new isolated substances. In this connection,the study of high polymer components will be most produ~t-ive. Among the known facts are the high temperature-resistance of high polymers containing fluorine and thetemperature-flexible silica oxide chain high polymer.From the latter chemical compound is evolved a hightemperature-resistant silicon-oxygen-metallic chain highpolymer. The high temperature-resistance characteristicsof high polymers containing phosphorus, boron and nit--rogen have been clarified gradually, Other element whichpredominate in high polymer chains should be exploredon a large scale. The development of studies of theelements in high polymer should be linked with the studyof inorganic high polymers. The structure and behaviorof the high polymer elements themselves present a newproblem.

It is entirely possible to create synthetic highpolymers by adding vinyl, which is capable of polymer-adding, or "kung-neng-t'uan,l" which is capable of conden-sation, to organic materials possessing special charact-eristics (such as dyestuffs, drugs, luminous substances,catalytic agents, stabilizing agents, etc,,), The prospectfor developing a synthetic high polymer having semi-conductive qualities is very promising, This is an en-tirely new problem.

(5) In the basic tasks and the directions fordevelopment given above are included problems of theorysuch as the reaction mechanism in the formation anddissociation of a high polymer, the structure and behav-ior of high polymers and the relationship between them,etc. These studies are related to polymerization,condensation, interchange and dissociation reaction mecha-nisms as well as the study of dynamics. Thus, improve-

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ment of old methods and discovery of new reactions aresubstantially assured. The statistical theory of highpolymers, the thermodynamic properties in solution andthe hydrodynamic behavior of high polymers, the ther-modynamic qualities of cohesive high plymers and themechanical and dielectric properties of molecular struct-ure -- all these need to be examined and formulated. Thiswork is of special significance to the understanding ofhigh polymers that are regular in structure and biologi-cally active.

Any advancement in theoretical research is boundto accelerate the development of high polymer chemistry.At the same time, neighboring or peripheral sciencessuch as high polymer physics, high polymer physicalchemistry, high polymer radioactive chemistry and highpolymer biochemistry will respond to the general develop-ment of high polymer science.

In short, the future development of high polymerchemistry in China has unlimited promise.

1198 END

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