CA2023380A1 - Silicon carboxide fibers from gel spinning cyclosiloxane polymer precursors - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a black glass fiber which is resistant to oxidation at a temperature of about 1350°C and has the empirical formula SiCxOy where x ranges from about 0.5 to about 2.0 and y ranges from about 0.5 to about 2Ø
This invention also relates to a process for preparing a black glass fiber comprising reacting a silicon hydride group with a silicon olefinic group in thepresence of a hydrosilylation catalyst to give a cyclosiloxane polymer. The polymer is then spun into fiber, hardened and then pyrolyzed to give a black glass fiber.

Description

202~380 W 2 O ~ SPlNNlNG
CYCLO~!~Q2~NE ~R~

BACKGROUND OF THE INVENTION

Silicon carbide and silicon carboxide fibers have many applications as high temperature structural materials. One method of preparing such fibers is that disclosed by Yajima et al. in U.S. Patent No. 4,283,376. The method disclosed in the 376 patent produces a polycarbosilane which contains some siloxane bonds by adding a polyborosiloxane to a po~silane as shown below.

~ sI ~ + -si-o-s-o-It is stated by the patentee that this reaction gives a polycarbosilane containing the following structurai units:

2 o lRl lR3 -8i-CH2- and - li_o_ R2 (A) R4 (B) where R1, R2, R3 and R4 each represent methyl, phenyl or hydrogen~ Only a ~mail number dthe i3 structural units are present In the poiycarbosilane. This poiycarbosilane can be spun into afiber and flrcd at 800 to 1800C in vacuum or an inen atmosphere to give a silicon carbide flber.
Another method for producing silicon carbide flbers is disclosèd in U.S.
Patent No. 4,100,233. This invoives preparing an orçianosNlcon high molecular wei~ht compound with sillcon and carbon as the main skeleton components.
This compound Is produc~d by the polycondensation of compounds which contain: 1) oniy Sl~ bonds; 2) Si-H and SI-C bond~, 3) Si-Halo~sn bonds, 4) 35 Si-N bonds, etc. Once the high molecular weight or~anosllicon compound is formed it is meitcd, spun into a fiber and heated to ~ive a sillcon carbide flber.

2 2023~0 Further, Great Britain Patent No. 1,359,576 discloses a method of forming a silicone fiber which involves the hydrolysis of organoalko~y-silanes, followed by mixing the hydrolyzed silane with polyethylene oxide, spinning this mixture and then heating above 600C. This produces a quartz fiber (SiO2) 5 which contains carbon.
Finally, ch~mical vapor deposition (CVD) using a gaseous mixture of hydrogen, argon and chlorosilanes can be used to prepare silicon carbide fibers. Usually monofilament carbon fibers are used as the core fiber. The vapors are fed into a raactor at abouit 1300C and the carbon fiber placed 10 therein, resuiting in the deposltion of SiC onto the core fiber. rnis method is very expensive.
The instant invention differs signiflcantiy from the prior art described above and also offers some advantages. First, the instant invention relates to acontinuous silicon carboxide fiber (herr~inafter referred to as a black glass fiber) 15 versus silicon carbide or qùartz fibers of the prior art. The black glass fibers of the present invention are resistant to oxidation at temperatures as high as 1350C. This has previously not been observed of a fiber containing a substantial amount of carbon.
The insbnt invention also provides a method of forming the black glass 2 o fiber. This method invoives first preparing a cydosiloxane polymer in solution, then spinning a fiber and flnally pyroly~ing the flber in a non-oxidizing atmosphere to give a black glass fiber. Specificaily, the cyclosiloxane polymer is prepared by reacting a silicon hydride group ~Si-H) with a silicon oleflnie group, e.g. SI-CH-CH2, in the presence of a cataiyst to form an ethylen~
25 linkage as shown below:
Si~H + CH2 - CH-Si- SiCH2CH2Si~
Thls reaction is known as hydrosilylat~on and the cataiyst employed is known as a hydrosiiylation cataiyst.
The hydrosilylation reaction dfflers from the reactions of the prior art 30 which are used to prepare a polymer in the following ways. The '376 patent involves reacting a poiysilane with a polyborosilane to give a polycarbosilane and an alkyl boron or boron hydride as a sidc product. In contrast to this reaction, the hydrosilylation reaction of the instant invention does not involveany boron in the reaction and no side product, i.e., boron hydride, is produced.35 The hydrosilylation reactlon is an addition reaction, i.e. adding hydrogen to a doubls bond.

3 2~23~80 The reaction described in the ~233 patent is also different from the hydrosilylation reaction. The ~233 patent describes a polycondensation reaction which involves producing radicals of the monomer which radicals then combine (via new Si-C bonds) into an organosilicon polymer with the elimination of a gas5 such as methane, hydrogen, etc. Again the hydrosilylation reaction does not form any byproduct gas and no new Si-C bonds are formed.
Finally, comparing the instant reaction with that of the '576 patent, it is noted that the '576 patent involves a hydrolysis reaction. There is no water present in the hydrosilylation reaction and thus, these two reactions are 10 completely dfflarent.
Once the polymer is formed, it can be forrn~d into a flber by spinning the polymer. This fiber is now hardened by passing it through a hot zone and then pyrolyzed under a non-oxidizing atmosphere to give a biack glass flber having the formula SiCXOy where x ranges from about 0.5 to about 2.0 and y ranges 15 from about 0.5 to about 2Ø Thus, the instant invention provides a black glass flber and a method of producing a black glass fiber in which the amount of carbon and oxygen in the fiber ean be readiiy controlled.

SUMMARy OF THE INVENTION
This invention relates to a blaek glass fiber and to a method for preparing a blaek gla8s flbcr. Thus, one embodiment is a continuous black glass fiber whleh IS resistant to oxldatlon at a temperature of about 1350C, is substantially amorphou8 and has the emplrieai formula SiCXOy where x ranges from about 0.5 to about 2.0 and y ranges from about 0.5 to about 2Ø
2 5 Another embodlment of this invention is a process for preparin~ a black glass fiber comprising:
a) formin~ a soluble eyelosiloxane poiymer by reactlng in solution and in the presenee of a catalytleaily efteetive amount of a hydrosilylation eataiyst a silleon hydride group with a silieon olefinie group wherein 1) sald sllleon hydride and silieon olefinie group are present in the same eyeloslloxane monomer having the formula ~3 where n is an integer from 3 to aboln 20, R is hydrogen, and R~ is an alkene having from 2 to about 20 carbon atoms and an olefinic carbon bonded directiy to silicon, or 2) said silicon hydride and silicon olefinic groups are present on two or mor~ dif~èrent cyclosiloxane monomers, at least one monomer having a silicon-hydride group and having said formula in which n is an integer *om 3 to about 20, R is hydrogen and R' iS an alkyl group having *om 1 to about 20 carbon atoms and at least one monomer having a silicon olefinic group and having said formula in which R is an alkene having from 2 to about 20 carbon atoms and which has an olefinic carbon directly bondeci to silicon and R' is an alkyl group having from 1 to about 20 carbon atoms;
b) forming a spinning solution from the solution containing a soluble cyclosiloxane poiymer;
c) splnning the spinninçi wlution to give a poiymeric cyclosiloxane flber;
d) heaUng tho poiymeric cyciosibxano flber at a temperature of about 50-200C and tor a timo sufficient to form a hardened polymeric cycloslbxane flber; and e) heatin~ the hudened polymerlc cyciosUoxane fiber at a tomporature ot about 700C to about 1400C In a non-oxidizing abnosphre for a timo suffldent to pyroiyze the polymeric flber into a black glass flber.
Other oblects and embodimonts will be foùnd in the tollowinçi further detailed description otthe pre~ent invention.

., , , 20233~

DETAILED DESCRIPTION OF THE INVENTION

As hereinbefore stated, this invention relates to a black glass fiber and to 5 a method of preparing black glass fibers. For the purposes of this specification and the appended claims, the following definition of terms will apply:
1) silicon ole~nic group means that a carbon with a double bond in an alkene group is bonded directly to a silicon atom;
2) poiymerizing means to make a polymer in a flowable state from tha cyclosiloxane monomers;
3) a hardened fiber is a fiber which has structural rigidity and cannot be easily deformed.
Thus, one embodiment of this invention is a method of preparing a black glass fiber. The first step in this process involves preparin~ a soluble 15 cyclosiloxane polymer. This soluble cyclosiloxane polymer is formed by reacting a silicon olefinic group with a silicon-hydride group in the presence of a hydrosilylation catalyst. The silicon-hydride and silicon olefinic groups can bepresent in the same cyclosiloxane monomer with the formula ¦tR

where n is an inte~er from 3 to about 20, R Is hydrogen, and R' is an alkene havln~i from 2 to about 20 carbon atoms and an olefinic carbon bonded directly 3 0 to sillcon. Aitemativeiy, the silicon-hydrid0 and sillcon oleflnlc groups can be present on two or morc dfflerent cyclosiloxane monomers at least one monomcr having said formula in which n is an inteçicr from 3 to about 20, R is hydro~n and R' Is an alkyl çiroup having from 1 to about 20 carbon atoms and at least one monomer having said formula in which R is an alkene havin~j from 2 35 to about 20 carbon atoms which has an olcflnic carbon dir~ctly bonded to silicon and R' is an alkyl ~roup having from 1 to about 20 carbon atoms.
Illugtrativc of the cyclosiloxancs which may bc used in this Inventlon are:
1 ,3,5,7-tetramethyitetrahydrocyclotetrasiloxane, 6 2 ~ 8 ~

1 ,3,5,7-tetravinyltetrahydrocyclotetrasiloxane, 1 ,3,s,7-tetravinyltetraethylcyclotetrasiloxane, l~3~s~7-tetravinyltetramethylcyclotetrasiloxane~
1 ,3,s-trimethyltrivinylcyclotrisiloxane, s 1,3,5-trivinyltrihydrocyclotrisiloxane, 1 ,3,5-trimethyltrihydrocyclotrisiloxane, 1 ,3,5,7,9-pentavinylpentahydrocyclopentasiloxane, 1 ,3,s,7,9-pentavinylpentamethylcyclopentasiloxane, 1,1,3,3,5,5,7,7-octavinylcyclotetrasiloxane, o 1,1,3,3,5,5,7,7-octahydrocyclotetrasiloxane, 1,3,5,7,9, 11 -hexavinylhexamethylcyclohexasiloxane, 1,3,5,7,9, 11 -hexamethylhexahydrocyclohexasiloxane, 1,3,5,7,9,1 1 ,13,15,17,19-decavinyldecahydrocyclodecasiloxane, 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29-pentadecavinylpentadecahydrocyclo-15 pentadecasiloxane,1 ,3,5,7-tetrapropenyltetrahydrocydotetrasiioxane, 1,3,5,7-tetrapentenyitetrapentylcyclotetrasiloxane and 1 ,3,5,7,9-pentadecenylpentapropylcycdopentasiloxane.
The poiymerization reaction is carrieci out In the presence of a 20 hydrosilylation cataiyst. The hydrosilylaffon catayst can be chosen from cataiysts that are well known in the art. Usuaiiy, the hydrosilylation catalyst is a metal compound where the metai is selected from the group consisting of platinum, iron, nickel, rhodium, cobait and manganeso. Illustrative of these compounds are nickol carbonyl, iron carbonyl, cobalt carbonyl, manganese 25 carbonyl, chloroplatinic add, platinum divinyltetramethyldisiloxane, platinumcarbonyl dichbrido, rhodlum trichbrido, and tris(triph~nylphosphine) plaUnum.
The metais themseives, platinum, rhodium, nbkel, iron, cobait and manganese, aro aiso gooci hydrosiiylation cataiysts. Of theso cataiysts, the ones containing platinum are preferred. The cataiyst may be added eithor as a heterogeneous 30 or homogeneous phase, aithough not with equivalerlt resuits. It is preferred to use a homoQeneous phase cataiyst. The concentration of the cataiyst may vary conslderabiy, but for economic reasons and convonienco, it is desirable that thecataiyst be present in an amount ranginçi from about 1 ppm to about 200 ppm as the metai in the monomeric solution.
3 5 It is also necessary that the poiymerization reaction be carried out in solution. The reason for carrying out tho reaction in soluUon is to control the 7 2~2338~
extent of polymerization and to control the viscosity of the resultant polymericsolution. The criteria to be used in selecting a solvent for preparing the solution containing the cyclosiloxane monomers and hydrosilylation catalyst are that the cyclosiloxane monomer be soluble in the solvent and that the solvent not react 5 with the cyclosiloxane monomer. It is preferable, though not necessary, that the hydrosilylation catalyst also be soluble in the organic solvent. Certain organic solvents are the types of solvents which fit these criteria. Specffically, aliphatic hydrocarbons, aromatic hydrocarbons and ethers may be used.
Illustrative of these solvents are toluene, benzene, xylene, hexane, pentane, 10 cyclohexane, heptane, pentene, hexene, tetrahydrofuran, benzyl ethyl ether, etc.
The actual polymerization reaction is carri~d out by combining a solution containing a hydrosilylation catalyst, preferably the catalyst is dissolved in the soivent, with a solution of the desired cyclosiloxane monomers. It is preferable, 15 though not necessary, that the solvents used to prepare the two solutions be the same. Upon comb~ning the two solutions, the polymerization reaction begins to take place. The polymerizat~on reaction can be carried out at bmperatures as low as 10C or at elevated temperatures, with the reaction proceeding at a faster rate at elevated temperatures. In order to control the 2 o poiymorization reaction, the maximum temperature for carrying out the polymerization reaction is about 250C. It is convenient to carry out the poiymerization reaction by heating the solvent containing the cyclosiloxane monomers anci catalyst to tho refiuxing temperature of the solvent. For oxamplo, N toluone is tho desired soivent, then the mixture is heatoci to a 2s tomperature ot about 105C. Thus a conveniont temperature range hr carrying out the reaction Is about 10C to about the refluxing temperature of the organicsoh~or~t.
It h Important that the polymerization reac~tion be carried out for a length of time sumcientto obtain a soluble cyclosiloxane polymer. ~he soluble 30 cydosiloxane polymer should have a molecularweight of at least 500.
However, the reaction should bo stoppod before the polymer becomes a gel or bofore occurrence of the gel point. For the purposes of this appllcatlon, a gel is defined as a cross-llnked polymor network swollen in a liquid modium. If tho polymer is aibwed to crossllnk, the polymer becomes insoluble and cannot bc 35 spun into a fiber. Although the amount of timo required to reach the gel point will depond on the reaction temperature and the concentration ol the catalyst, 2023~8~
generaliy about 30 to about 400 minutes is sufficient to ensure polymerization and give a solution containing a soluble cyclosiloxane polymer.
The polymer solution obtained from the above reaction may or may not have the proper properties for forming polymerie cyclosiloxane fibers by the well 5 known spinning teehnique. Therefore, the solution deseribed above must be formed into a spinning solution. A spinning solution is a solution whieh has theproper viscosity sueh that a fiber may be drawn or spun from said solution.
One way to form a spinning solution is to distill a portion of the solvent undervacuum until the spinning solution has the proper viscosity for spinning. This o viseosity can vary widely, but generally it is desirabie to have a spinning solution with a viscosity of about 300 to about 3,000 poise when measured at a shear rate of about 20-SOO sec~1.
Another method of obtaining a spinning solution is to first preeipitate the cyelosiloxane poiymer by adding a precipitating agentto the solution, thereby 15 preeipitating the cyclosiloxane polymer. The precipitating agent is any liquid in whieh the cyelosiloxane polymer is ~nsoiuble. Illustrative of these precipitating agents are methanol, ethanol, propanoi, and mixtures thereof. The precipitated poiymer is now isolated and redissoiveci in an organie soivent so that the viseosity of the r~sulting solution is about 300 to about 3,000 poise when 20 measured at a shear rate ot about 20 to about 500 see~1. The organie solvent in whieh the eyelosiloxane poiymer i8 redissoh~ed may be the same or a dffloront solvent from the organb soivenit in whieh the eyelo~iloxane polymer was ori~lnaily formed. Toluene is the preforred ~olvent.
Yet another methooi of forming a spinnin~ solution b to add a soluble 2 5 hi~h molecular wolght pdymer to the solution in order to Inerease the~viscosity of the solution anci forrn a spinning solution. ThiQ solubb high moleeular weight polyrr~r may be ~leeted *om the group eonsisting of poiymethylhydrosibxane, vinyimethyi~lbxano poiymer, polydlmethylsiloxane, anci poi~il~iuiox~. For examph, polymothylhydrodbxane of moleeular 30 weight of about 5,000 may be addoci to the sol~nion to ~he a spinning solution.
The arnount of hl~h moloeular weight poiymer whieh may be added to the solution depends on tho viseosity of the soiution, but goneraiiy *om about 1 to about 10 weight pereent of the solution should be added. Thls additional poiymer may be added to the solu~on either before or atter the formation of the 35 eydosiioxane poiymer. Rnaiiy, the viseosity of the spinning solutlon may be 9 ~2338~
controlled by bolh adding a high molecular weight polymer and by vacuum distilling some of the organic solvent.
Regardless of how the spinning solution is formed, the fibers are formed from the spinning solution by spinning techniques well known in the art. One 5 such method is to spin the solution through a nozzle and then heat the formed fiber in flowing air at a temperature of about 50-200C. ~eating the fiber hardens the fiber. The amount of time needed to harden the fiber is usually verysmall, on the order of about 0.1 to about 5 seconds. The usu~ process is to continuously pull the fiber through a heaUng zone at a rate such that the e residence time in the heating zone is about 0.1 to about 5 seconds. Hardening of the fiber takes place by the process of either removing all the solvent from the fiber, or uoss-linking the cyclosiloxane poiymer or both. Both processes occur at the higher temperatures. The reason for desiring a hardened fiber is so that the shape of the flber does not change upon pyrolysis.
lS Another spinning procedure involves extruding the spinning solution through an aperture into a coagulation bath, thereby hardening the fiber. The eoagulation bath is composed of a liquid medium in which the cyclosiloxane polymer is insoluble, for example a 1:1 methanol/ethanol mixture. However, it is preferreci to use a high boiling medium so that eross-linking ean also take 20 plaee. For oxample, the coagulation bath may consist of giycerin which is heated abovo 100C. The resuitant fiber may be extraeted using a volatile soivent and dried.
Regardless of how the poiymer fiber is formed, the polymer flber is next eonvened into a eeramie blaek glass flber by pyroiyzin~ the polymer flber in a 2S non oxidizin~ atmosphere at a bmperature of about 700 to about 1400C.
The non-oxidizin~ atmosphere may be nitro~en, ar~on, or a vaeuum. The amount of ffme roc-uirec to form the blaek ~;las~ fiber ean vary dependin~ on the pyroiysls bmperature but generaiiy a time of about 2 minutes to about 30 hours is ~ufRcien~t to eompleteiy form the blaek ~b~ fiber.
The blaek ~lass flber may be represented by the formula SiCxOy, where x ran~es *om about 0.5 to about 2.0, and y ranges *om about 0.5 to about 2Ø
This fiber is another embodlment of this invention. The black glass flber of this invenffon is eharaeterizec In that it is highiy resistant to oxidatlon. Sarnples of this biaek ~lass were heatod in air to about 1350C and showed oniy about a 1% wei~ht loss. X-ray anaiysis of these fibers aiso shows that the fibers are substantiaiiy amorphous with oniy about 1% of an unidentifieci crystalline phase 202338~

present. The fibers of this invention as produced in the laboratory had an average diameter of about 120 microns and a tensile strength of about 250-400 MPa. However, using commercial spinning apparatus one can obtain fibers with a diameter of about 15 to about 25 microns and a tensile strength of 5 several times greater than observed from the fibers produced on a laboratory scale. Finally, the black glæs fibers of this invention retain at least 70% of their initial strength after heating in air at 1 ,000C for one hour.
As stated herein, these fibers have app~ications as high temperature structural materiais. Other uses for these fibers are fiber reinforced metals, fire-e retardant cloths, airplane structural materials, etc.
The following examples are given for illustrative purposes only. It is to beunderstood that these examples are not intended æ an undue limitation on the broad scope of the invention as set forth in the appended claims.

EXAMPLE I
3.45 ml of tetravinyitetrarnethylcyclotetræiloxane and 2.40 ml of tetramethylcylcotetræiloxane were dissoived in 62.5 ml of toluene. To this solutlon there were added 0.02 ml of a cataiyst solution containing 1% platinum dTvinyltetramethyldisiloxane in toluene. The solu~ion was poured into a three-20 neck flask and refluxed for 3 hours. Afterthe solution was cooled to room temperature, the poiymer product was precipitated by adding a 1:1 mixture of CH3OH/C2H5OH to the toluene solution. A white powder was obtained. A
spinninçi solution containlng 85 weiçiht percent of tho cyclosiloxane pglymer and 15 weight percent toluene was prepared. The vbco~ of the spinning solution Wa~l about 800 po~o at a shear rate of 384 sec~1 at 22C. The viscosity was measureci u~in~ a Haake viscometer with a ~Cone and Platr sensor system.
Cyciosiloxane poiymer fibers of 2-3 feet i~ were hanci-drawn by using simple pulling techniques. The drawn flbers were drbd and fu~her hardened by intense infrared radiation.
The cyclosiloxane poiymer flbers were placed h a fumace and heat-treated in flowin~ nitro~en to 1200C at a heatin~ rate of 200C por hour. A
black glass flber was obWned. The char yieid of tho pyroiy~is stsp is 84%.
Eiementai anaiysis showed that the black ~lass contained 26.1% carbon by weight. Thi~ carbonaceous black ~las~ had the emplricai tormula of 3s SiC1 371 03 as determined by elementai anaiysls.

~233~
The black glass ~Ibers were gro~nd into powders and tested for their thermal stability by thermogravimetric analysis ~rGA). It was found that the carbonaceous black glass lost less than 0.6% by weight when heated in flowing air to 1150C at a heating rate of 10C per minute. In another TGA experiment, 5 the black glass powders were heated in flowing air to 14sOC at a heating rateof 10C per minute. The weight of the sample remained constant within 1.5 waight pereent up to 1350C. However, the sampb gained 3.5% by weight when heated from 1350C to 145~C.
X-ray diffraetion of the blaek glass indieated a predominantly amorphous o or miuoerystalline structure. Several unidentified crystalline lines were observed. The pereentage of crystalline phase was estimated to be less than 1%.

12.4 ml of vinylmethyleyelosiloxane eontaining mixtures of cydotetramer lS to cyeiohexamer, 7.00 ml of methylhydroeyeiosiloxane eontaining mixtures of cyelotetramer to eyelohexamer and 1.60 ml poiymethylhydrosiloxane of moleeularweight about 5,000 were mixed and dissoived in 190 ml toluene. To this solution there were added 0.03 ml ot a solution eontaining 3% platinum divinyitetramethyldlsiloxane in toluene. The solution was refiuxed for 4 hours.
20 Tolueno was removed from the refiux solution at ambienttemperature by distillation undor redueed pressure until the remaining solution had a viseosityof 500 pols~ at a shear rato of 384 see-1. Cyeiosiloxane poiym~r fibers were drawn from the concontrated poiymor solution.
The eycbdbxano poiymer fibers were pyrolyzed in flowin~ nitrogen to 25 1,000C. The hating cyeie ineiuded hoating to 500C at 200C/hour, held at 500C tor 1 hour, heating to 1,000C at 200C/hour and eooling to room temperature at 200C/hour. Carbon containin9 blaek ~lass fibers were produceci. Seannhg i--ieetron Mieroseopo (SEM) pietures of the blaek ~lass fibers showec that the fiber had a smooth sur~aeo with a smail number ot 30 pinholes and a~cks. The cross-section o!the flber was sli~htly obbng and its diameter was about 125 mierons. The tensile stren~th otthe nbers at room temperature was between 250 400 MPa ~or these lar~e diameter fibers and the Youn~s modulw was in the range ot 45 60 GPa. The tensile strsngth of the fibers atler heat-treating in air for one hour (with a heating and coollng rate ot 250C/hour) was in the range of 150-~Oû MPa. In general, the fiber retained about 70% of its initial strength after 1 hour at 1,0ûûC.
Thus, having described the invention in detail, it will be understood by those skilled in the art that certain variations and modifications may be made 5 without departing from the spWt and scope of the invention as defined herein and in the appended claims.

, ,

Claims (16)

1. A process for preparing a black glass fiber comprising:
a) forming a soluble cyclosiloxane polymer by reacting in solution and in the presence of a catalytically effective amount of a hydrosilylation catalyst a silicon hydride group with a silicon olefinic group wherein 1) said silicon hydride and silicon olefinic group are present in the same cyclosiloxane monomer having the formula where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and an olefinic carbon bonded directly to silicon, or 2) said silicon hydride and silicon olefinic groups are present on two or more different cyclosiloxane monomers, at least one monomer having a silicon-hydride group and having said formula in which n is an integer from 3 to about 20, R is hydrogen and R' is an alkyl group having from 1 to about 20 carbon atoms and at least one monomer having a silicon olefinic group and having said formula in which R is an alkene having from 2 to about 20 carbon atoms and which has an olefinic carbon directly bonded to silicon and R' is an alkyl group having from 1 to about 20 carbon atoms;
b) forming a spinning solution from the solution containing a soluble cyclosiloxane polymer;
c) spinning the spinning solution to give a polymeric cyclosiloxane fiber;
d) heating the polymeric cyclosiloxane fiber at a temperature of about 50-200°C and for a time sufficient to form a hardened polymeric cyclosiloxane fiber; and e) heating the hardened polymeric cyclosiloxane fiber at a temperature of about 700°C to about 1400°C in a non-oxidizing atmosphere for a time sufficient to pyrolyze the polymeric fiber into a black glass fiber.

2. The process of Claim 1 where the soluble cyclosiloxane polymer is formed at a temperature of about 10°C to about 250°C, and a time sufficient to form the soluble cyclosiloxane polymer but less than a time sufficient to reach the gel point.

3. The process of Claim 1 where the hydrosilylation catalyst is a metal or a metal compound wherein the metal is selected from the group consisting of platinum, iron, nickel, rhodium, cobalt and manganese, and is present in an amount ranging from about 1 ppm to about 200 ppm as the metal.

4. The process of Claim 3 where the metal compound is platinum divinyltetramethyldisiloxane.

5. The process of Claim 1 further characterized in that an organic solvent is used to prepare the solution containing the cyclosiloxane monomer and hydrosilylation catalyst.

6. The process of Claim 5 where the organic solvent is selected from the group consisting of xylene, toluene, benzene and tetrahydrofuran.

7. The process of Claim 1 further characterized in that the spinning solution has a viscosity of about 300 to about 3,000 poise when measured at a shear rate of about 20 to about 500 sec-1.

8. The process of Claim 1 where the step of forming a spinning solution is further characterized by distilling under vacuum a portion of the organic solvent until the viscosity of the resultant spinning solution is about 300 to about 3,000 poise when measured at a shear rate of about 20 to about 500 sec-1.

9. The process of Claim 1 where the step of forming a spinning solution is further characterized by adding a precipitating agent to the solution containing a soluble cyclosiloxane monomer, thereby precipitating a cyclosiloxane polymer, isolating the polymer and redissolving the cyclosiloxane polymer in an organic solvent, thereby providing a spinning solution with a viscosity of about 300 to about 3,000 poise when measured at a shear rate of about 20 to about 500 sec-1.

10. The process of Claim 9 where the precipitating agent is selected from the group consisting of methanol, ethanol, propanol, and mixtures thereof.

11. The process of Claim 9 where the organic solvent is selected from the group consisting of xylene, toluene, benzene and tetrahydrofuran.

12. The process of Claim 1 where the non-oxidizing atmosphere is nitrogen, argon or a vacuum.

13. The process of Claim 1 where the solution also contains a high molecular weight polymer, present in an amount from about 1 to about 10 weight percent of the solution.

14. The process of Claim 13 where the polymer is selected from the group consisting of polymethylhydrosiloxane, vinylmethylsiloxane polymer, polymethysiloxane and polysilsequioxane.

15. The product of the process of Claim 1.

16. A continuous black glass fiber which is resistant to oxidation at a temperature of about 1350°C, is substantially amorphous, and has the empirical formula SiCxOy where x ranges from about 0.5 to about 2.0 and y ranges from about 0.5 to about 2Ø