it is thus an object of the invention to provide improved shrink rates without appreciably reducing tensile strengths for polypropylene tape fibers . a further object of the invention is to provide a class of additives that , in a range of concentrations , will provide low shrinkage and / or higher tensile strength levels for such inventive tape fibers ( and yarns made therefrom ). a further object of the invention is to provide a carpet made with a polypropylene backing exhibiting very low heat shrinkage rates . another object of the invention is to provide a specific method for the production of nucleator - containing polypropylene tape fibers permitting the ultimate production of such low - shrink , high tensile strength , fabrics therewith . yet another object of the invention is to provide a carpet article having a backing comprising a majority of relatively inexpensive polypropylene tape fibers that exhibits very low shrinkage . accordingly , this invention encompasses a polypropylene tape fiber , wherein said fiber comprises in excess of 2000 ppm and up to about 5000 ppm of a nucleator compound , and wherein said fiber exhibits a tensile strength of at least 3 grams / denier . also encompassed within this invention is a polypropylene tape fiber , wherein said fiber comprises in excess of 2000 ppm , up to about 5000 ppm , of a nucleator compound , wherein said fiber exhibits a shrinkage rate after exposure to 150 ° c . hot air of at most 4 %, and wherein said fiber further exhibits a tensile strength of at least 2 . 5 grams / denier . also , this invention encompasses a polypropylene tape fiber , wherein said fiber exhibits an x - ray scattering long period of at least 20 . certain yarns and fabric articles comprising such inventive fibers are also encompassed within this invention . of particular concern is a carpet article having a top side and a bottom side , wherein a fiber substrate of either tufted fiber , berber fiber , or like type is attached to said top side and a backing comprising a majority of single filament polypropylene fibers having a denier of at least 50 , wherein said fibers comprise in excess of 2000 ppm , up to about 5000 ppm , of a nucleator compound , is attached to said bottom side . preferably , such a carpet article exhibits very low shrinkage rates on par with those noted above . furthermore , this invention also concerns a method of producing such fibers comprising the sequential steps of a ) extruding a heated formulation of polypropylene comprising at least an excess of 2000 ppm up to about 5000 ppm , preferably between at least about 2100 ppm and 4000 ppm , more preferably between about 2250 ppm and 3500 ppm , and most preferably between about 2250 and 3000 ppm , of a nucleator compound into a film or tube ; b ) immediately quenching the film or tube of step “ a ” to a temperature which prevents orientation of polypropylene crystals therein ; c ) slitting said film or tube with cutting means oriented longitudinally to said film or tube thereby to produce individual tape fibers therefrom ; d ) mechanically drawing said individual tape fibers at a draw ratio of at least 5 : 1 while exposing said fibers to a temperature of at between 200 and 400 ° f ., preferably between 260 and 330 ° f ., and most preferably between 270 and 300 ° f ., thereby permitting crystal orientation of the polypropylene therein ; e ) exposing said fibers to a temperature of between 300 ° f . and 450 ° f . to set the fibers . preferably , step “ b ” will be performed at a temperature of at most 95 ° c . and at least about 5 ° c ., preferably between 5 and 60 ° c ., and most preferably between 10 and 40 ° c . ( or as close to room temperature as possible for a liquid through simply allowing the bath to acclimate itself to an environment at a temperature of about 25 - 30 ° c .). again , such a temperature is needed to ensure that the component polymer ( being polypropylene , and possibly other polymeric components , such as polyethylene , and the like , as structural enhancement additives therein that do not appreciably affect the shrinkage characteristics thereof ) does not exhibit orientation of crystals . alternately , step “ c ” can be eliminated by extruding multiple tape of the desired width without the slitting requirement “ c ”. upon the heated draw step , such orientation is effectuated which has now been determined to provide the necessary rigidification of the target tape fibers and thus to increase the strength and modulus of such fibers . the drawing speed to line speed ratio should exceed at least five times that of the rate of movement of the film to the cutting means . preferably , such a drawing speed is at from 400 - 1500 feet / minute , while the prior speed of the film to the cutting means from about 50 - 400 feet / minute , with the drawing speed ratio between the two areas being from about 3 : 1 to about 15 : 1 , and is discussed in greater detail below , as is the preferred method itself . the final heat - setting temperature is necessary to “ lock ” the polypropylene crystalline structure in place after extruding and drawing . such a heat - setting step generally lasts for a portion of a second , up to potentially a couple of minutes ( i . e ., from about { fraction ( 1 / 10 )} th of a second , preferably about ½ of a second , up to about 3 minutes , preferably greater than ½ of a second ). the heat - setting temperature must be well in excess of the drawing temperature and must be at least 265 ° f ., more preferably at least about 290 ° f ., and most preferably at least about 300 ° f . ( and as high as 450 ° f .). the term “ mechanically drawing ” is intended to encompass any number of procedures which basically involve placing an extensional force on fibers in order to elongate the polymer therein . such a procedure may be accomplished with any number of apparatus , including , without limitation , godet rolls , nip rolls , steam cans , hot or cold gaseous jets ( air or steam ), and other like mechanical means . such tape yarns may also be produced through extruding individual fibers of high aspect ratio and of a sufficient size , thereby followed by drawing and heatsetting steps in order to attain such low shrinkage rate properties . all shrinkage values discussed as they pertain to the inventive fibers and methods of making thereof correspond to exposure times for each test ( hot air and boiling water ) of about 5 minutes . the heat - shrinkage at about 150 ° c . in hot air is , as noted above , at most 4 . 0 % for the inventive fiber ; preferably , this heat - shrinkage is at most 3 %; more preferably at most 2 %; and most preferably at most 1 %. also , the amount of nucleating agent present within the inventive fiber is in excess of 2000 ppm ; preferably this amount is at least 2100 ppm ; and most preferably is at least 2250 ppm , up to a preferred maximum ( for tensile strength retention ) of about 5000 ppm , more preferably up to 4000 ppm , and most preferably as high as 3000 ppm . any amount within this range should suffice to provide the desired shrinkage rates after heat - setting of the fiber itself . furthermore , it has now been determined that the presence of an excess of 2000 ppm and 5000 ppm of a nucleator compound within polypropylene fibers for incorporation within primary ( or secondary ) carpet backing provides the highly desirable result of little appreciable shrinkage of the backing , as well as of a tufted substrate / backing composite , or even of an entire carpet article . thus , any low - shrink carpet backing component comprising a majority of polypropylene fibers including such nucleator compound ( in the requisite amounts , preferably between 2100 and 4000 ppm , and most preferably between about 2250 and 3000 ppm ), provides the necessary low shrinkage properties . fibers and / or yarns of the inventive tape type , as well as polypropylene staple , multifilament , and monofilament , types , are available in such capacity for such improved , low - shrink carpet articles . the term “ polypropylene ” is intended to encompass any polymeric composition comprising propylene monomers , either alone or in mixture or copolymer with other randomly selected and oriented polyolefins , dienes , or other monomers ( such as ethylene , butylene , and the like ). such a term also encompasses any different configuration and arrangement of the constituent monomers ( such as syndiotactic , isotactic , and the like ). thus , the term as applied to fibers is intended to encompass actual long strands , tapes , threads , and the like , of drawn polymer . the polypropylene may be of any standard melt flow ( by testing ); however , standard fiber grade polypropylene resins possess ranges of melt flow indices between about 1 and 50 . contrary to standard plaques , containers , sheets , and the like ( such as taught within u . s . pat . no . 4 , 016 , 118 to hamada et al ., for example ), fibers clearly differ in structure since they must exhibit a length that far exceeds its cross - sectional area ( such , for example , its diameter for round fibers ). fibers are extruded and drawn ; articles are blow - molded or injection molded , to name two alternative production methods . also , the crystalline morphology of polypropylene within fibers is different than that of standard articles , plaques , sheets , and the like . for instance , the dpf of such polypropylene fibers is at most about 5000 ; whereas the dpf of these other articles is much greater . polypropylene articles generally exhibit spherulitic crystals while fibers exhibit elongated , extended crystal structures . thus , there is a great difference in structure between fibers and polypropylene articles such that any predictions made for spherulitic particles ( crystals ) of nucleated polypropylene do not provide any basis for determining the effectiveness of such nucleators as additives within polypropylene fibers . the terms “ nucleators ”, “ nucleator compound ( s )”, “ nucleating agent ”, and “ nucleating agents ” are intended to generally encompass , singularly or in combination , any additive to polypropylene that produces nucleation sites for polypropylene crystals from transition from its molten state to a solid , cooled structure . hence , since the polypropylene composition ( including nucleator compounds ) must be molten to eventually extrude the fiber itself , the nucleator compound will provide such nucleation sites upon cooling of the polypropylene from its molten state . the only way in which such compounds provide the necessary nucleation sites is if such sites form prior to polypropylene recrystallization itself . thus , any compound that exhibits such a beneficial effect and property is included within this definition . such nucleator compounds more specifically include dibenzylidene sorbitol types , including , without limitation , dibenzylidene sorbitol ( dbs ), monomethyldibenzylidene sorbitol , such as 1 , 3 : 2 , 4 - bis ( p - methylbenzylidene ) sorbitol ( p - mdbs ), dimethyl dibenzylidene sorbitol , such as 1 , 3 : 2 , 4 - bis ( 3 , 4 - dimethylbenzylidene ) sorbitol ( 3 , 4 - dmdbs ); other compounds of this type include , again , without limitation , sodium benzoate , na - 11 , hpn - 68 , and the like ( basically a nucleator that is not also a colorant , thereby capable of producing a nucleated uncolored fiber ). the concentration of such nucleating agents ( in total ) within the target polypropylene fiber is at least in excess of 2000 ppm up to 5000 ppm , preferably at least 2100 ppm to 4000 ppm , and most preferably from 2250 to 3000 ppm . furthermore , such inventive tape fibers must be produced by basically the slitting of extruded films or tubes as outlined above . also , without being limited by any specific scientific theory , it appears that the shrink - reducing nucleators which perform the best are those which exhibit relatively high solubility within the propylene itself . thus , compounds which are readily soluble , such as 1 , 3 : 2 , 4 - bis ( p - methylbenzylidene ) sorbitol provides the lowest shrinkage rate for the desired polypropylene fibers . the dbs derivative compounds are considered the best shrink - reducing nucleators within this invention due to the low crystalline sizes produced by such compounds . other nucleators , such as na - 11 and hpn - 68 ( disodium [ 2 . 2 . 1 ] heptane bicyclodicarboxylate ), also provide acceptable low - shrink characteristics to the target polypropylene fiber and thus are considered as potential nucleator compound additives within this invention . basically , the selection criteria required of such nucleator compounds are particle sizes ( the lower the better for ease in handling , mixing , and incorporation with the target resin ), particle dispersability within the target resin ( to provide the most effective nucleation properties ), and nucleating temperature ( e . g ., crystallization temperature , determined for resin samples through differential scanning calorimetry analysis of molten nucleated resins ), the higher such a temperature , the better . it has been determined that the nucleator compounds that exhibit good solubility in the target molten polypropylene resins ( and thus are liquid in nature during that stage in the fiber - production process ) provide effective low - shrink characteristics . thus , low substituted dbs compounds ( including dmdbs and p - mdbs ) appear to provide fewer manufacturing issues as well as lower shrink properties within the finished polypropylene fibers themselves . thus , 3 , 4 - dmdbs and p - mdbs are preferred , although , any of the above - mentioned nucleators may be utilized within this invention as long as the x - ray scattering measurements are met or the low shrink requirements are achieved through utilization of such compounds . mixtures of such nucleators may also be used during processing in order to provide such low - shrink properties as well as possible organoleptic improvements , facilitation of processing , or cost . in addition to those compounds noted above , sodium benzoate and na - 11 are well known as nucleating agents for standard polypropylene compositions ( such as the aforementioned plaques , containers , films , sheets , and the like ) and exhibit excellent recrystallization temperatures and very quick injection molding cycle times for those purposes . the dibenzylidene sorbitol types exhibit the same types of properties as well as excellent clarity within such standard polypropylene forms ( plaques , sheets , etc .). for the purposes of this invention , it has been found that the dibenzylidene sorbitol types are preferred as nucleator compounds within the target polypropylene fibers . the closest prior art references teach the addition of nucleator compounds to general polypropylene compositions ( such as in u . s . pat . no . 4 , 016 , 118 , referenced above ). however , some teachings include the utilization of certain dbs compounds within limited portions of fibers in a multicomponent polypropylene textile structure . for example , u . s . pat . nos . 5 , 798 , 167 to connor et al . and 5 , 811 , 045 to pike , both teach the addition of dbs compounds to polypropylene in fiber form ; however , there are vital differences between those disclosures and the present invention . for example , both patents require the aforementioned multicomponent structures of fibers . thus , even with dbs compounds in some polypropylene fiber components within each fiber type , the shrink rate for each is dominated by the other polypropylene fiber components which do not have the benefit of the nucleating agent . also , there are no lamellae that give a long period ( as measured by small - angle x - ray scattering ) thicker than 20 nm formed within the polypropylene fibers due to the lack of a post - heatsetting step being performed . again , these thick lamellae provide the desired inventive higher heat - shrink fiber . also of importance is the fact that , for instance , connor et al . require a nonwoven polypropylene fabric laminate containing a dbs additive situated around a polypropylene internal fabric layer which contained no nucleating agent additive . the internal layer , being polypropylene without the aid of a nucleating agent additive , dictates the shrink rate for this structure . furthermore , the patentees do not expose their yarns and fibers to heatsetting procedures in order to permanently configure the crystalline fiber structures of the yarns themselves as low - shrink is not their objective . in addition , spruiell , et al , journal of applied polymer science , vol . 62 , pp . 1965 - 75 ( 1996 ), reveal using a nucleating agent , mdbs , at 0 . 1 %, to increase the nucleation rate during spinning , but not for tape fibers . however , after crystallizing and drawing the fiber , spruiell et al . do not expose the nucleated fiber to any heat , which is necessary to impart the very best shrinkage properties , therefore the shrinkage of their fibers was similar to conventional polypropylene fibers without a nucleating agent additive . of particular interest and which has been determined to be of primary importance in the production of such inventive low - shrink polypropylene fibers , is the discovery that , at the very least , the presence of nucleating agent within heat - set polypropylene fibers ( as discussed herein ), provides high long period measurements for the crystalline lamellae of the polypropylene itself . this discovery is best explained by the following : polymers , when crystallized from a melt under dynamic temperature and stress conditions , first supercool and then crystallize with the crystallization rate dependent on the number of nucleation sites , and the growth rate of the polymer , which are both in turn related to the thermal and mechanical working that the polymer is subjected to as it cools . these processes are particularly complex in a normal fiber drawing line . the results of this complex crystallization , however , can be measured using small angle x - ray scattering ( saxs ), with the measured saxs long period representative of an average crystallization temperature . a higher saxs long period corresponds to thicker lamellae ( which are the plate - like polymer crystals characteristic of semi - crystalline polymers like pp ), and which is evidenced by a saxs peak centered at a lower scattering angle than for comparative unnucleated polypropylene tape fibers . the higher the crystallization temperature of the average crystal , the thicker the measured saxs long period will be . further , higher saxs long periods are characteristic of more thermally stable polymeric crystals . crystals with shorter saxs long periods will “ melt ”, or relax and recrystallize into new , thicker crystals , at a lower temperature than those with higher saxs long periods . crystals with higher saxs long periods remain stable to higher temperatures , requiring more heat to destabilize the crystalline structure . in highly oriented polymeric samples such as fibers , those with higher saxs long periods will remain stable to higher temperatures . thus the shrinkage , which is a normal effect of the relaxation of the highly oriented polymeric samples , remains low to higher temperatures than in those highly oriented polymeric samples with lower saxs long periods . in this invention , as is evident from these measurements , the nucleating additive is used in conjunction with a thermal treatment to create fibers exhibiting a center of the saxs scattering peak of at most 0 . 4 degrees , which corresponds to thicker lamellae that in turn are very stable and exhibit low shrinkage up to very high temperatures . furthermore , such fibers may also be colored to provide other aesthetic features for the end user . thus , the fibers may also comprise coloring agents , such as , for example , pigments , with fixing agents for lightfastness purposes . for this reason , it is desirable to utilize nucleating agents that do not impart visible color or colors to the target fibers . other additives may also be present , including antistatic agents , brightening compounds , clarifying agents , antioxidants , antimicrobials ( preferably silver - based ion - exchange compounds , such as alphasan ® antimicrobials available from milliken & amp ; company ), uv stabilizers , fillers , and the like . furthermore , any fabrics made from such inventive fibers may be , without limitation , woven , knit , non - woven , in - laid scrim , any combination thereof , and the like . additionally , such fabrics may include fibers other than the inventive polypropylene fibers , including , without limitation , natural fibers , such as cotton , wool , abaca , hemp , ramie , and the like ; synthetic fibers , such as polyesters , polyamides , polyaramids , other polyolefins ( including non - low - shrink polypropylene ), polylactic acids , and the like ; inorganic fibers such as glass , boron - containing fibers , and the like ; and any blends thereof . of particular interest as end - uses for such inventive tape fibers are primary carpet backings and thus carpets comprising such backing components . these are described in greater detail below . furthermore , woven fabrics comprising such fibers are highly desirable as well for such areas as geotextiles , supersacks , and the like , basically any end - use requiring strong fibers at low cost . the accompanying drawings , which are incorporated in and constitute a part of this specification , illustrate a potentially preferred embodiment of producing the inventive low - shrink polypropylene fibers and together with the description serve to explain the principles of the invention wherein : [ 0026 ] fig1 is a schematic of the potentially preferred method of producing low - shrink polypropylene tape fibers . [ 0027 ] fig2 is a side view of a preferred carpet article comprising the inventive fibers within a backing . [ 0028 ] fig1 depicts the non - limiting preferred procedure followed in producing the inventive low - shrink polypropylene tape fibers . the entire fiber production assembly 10 comprises a mixing manifold 11 for the incorporation of molten polymer and additives ( such as the aforementioned nucleator compound ) which then move into an extruder 12 . the extruded polymer is then passed through a metering pump 14 to a die assembly 16 , whereupon the film 17 is produced . the film 17 then immediately moves to a quenching bath 18 comprising a liquid , such as water , and the like , set at a temperature from 5 to 95 ° c . ( here , preferably , about room temperature ). the drawing speed of the film at this point is dictated by draw rolls and tensionsing rolls 20 , 22 , 24 , 26 , 28 set at a speed of about 100 feet / minute , preferably , although the speed could be anywhere from about 20 feet / minute to about 200 feet / minute , as long as the initial drawing speed is at most about ⅕ th that of the heat - draw speed later in the procedure . the quenched film 19 should not exhibit any appreciable crystal orientation of the polymer therein for further processing . sanding rolls 30 , 31 , 32 , 33 , 34 , 35 , may be optionally utilized for delustering of the film , if desired . the quenched film 19 then moves into a cutting area 36 with a plurality of fixed knives 38 spaced at any distance apart desired . preferably , such knives 38 are spaced a distance determined by the equation of the square root of the draw speed multiplied by the final width of the target fibers ( thus , with a draw ratio of 5 : 1 and a final width of about 3 mm , the blade gap measurements should be about 6 . 7 mm ). upon slitting the quenched film 19 into fibers 40 , such fibers are moved uniformly through a series of nip and tensioning rolls 42 , 43 , 44 , 45 prior to being drawn into a high temperature oven 46 set at a temperature level of between about 280 and 350 ° f ., in this instance about 310 ° f ., at a rate as noted above , at least 5 times that of the initial drawing speed . such an increased drawing speed is effectuated by a series of heated drawing rolls 48 , 50 ( at temperatures of about 360 - 450 ° f . each ) over which the now crystal - oriented fibers 54 are passed . a last tensioning roll 52 leads to a spool ( not illustrated ) for winding of the finished tape fibers 54 . turning to fig2 then , an inventive carpet article 110 is shown comprising a pile layer 112 comprising tufted fibers 114 tufted through a primary backing layer or tufting substrate comprising the inventive fibers 113 ( which could be woven , knit , or non - woven in structure and comprise , as additional fibers , any type of natural fibers , such as cotton , and the like , or synthetic fibers , such as polyamide , and the like ; preferably , it is a woven substrate comprising polyamide fibers ), and embedded within one or more adhesive layers 115 , to which is attached a stabilizing layer 116 ( such as a glass mat ), and a foam or cushion layer 118 ( which may be a fabric , such as a felt , or resin , such as polyvinyl chloride other like compound ; preferably , it is polyurethane foam ). the stabilizing layer 116 is adhered to both the pile layer 112 and a cushion layer 118 to form the desired carpet article 110 . the inventive primary backing layer 113 , comprising such low - shrink polypropylene tape fibers , thus accords the desired low - shrink characteristics to the entire carpet article 110 itself . of course , alternative configurations and arrangements of backing layers ( such as an increase or decrease in the number required ) as well as types of fibers ( such as berber , short pile , and the like ) within the pile layer may be employed , as well as myriad other variations common within the carpet art and industry . see , for example , u . s . pat . nos . 6 , 203 , 881 or 6 , 468 , 623 , as examples of such carpet products . the following non - limiting examples are indicative of the preferred embodiment of this invention : the carpet backing slit film fibers were made on the standard production equipment as described above at a production rate of 500 ft / min as follows : a 3 . 5 - 3 . 8 melt flow homopolymer polypropylene resin ( p4g32 - 050 , from huntsman ) was blended with an additive concentrate consisting of 4 mfi homopolypropylene resin and a nucleator in amounts as listed below in table 1 . the blending ratio was changed to adjust the final additive level , as shown in the table below . this mixture , consisting of pp resin and the additive , was extruded with a single screw extruder through a film dye approximately 72 inches wide . the pp flow was adjusted to give a final tape thickness of approximately 0 . 0025 inches . the molten film was quenched in room temperature ( about 25 ° c .) water , then transferred by rollers to a battery of knives , which cut it into parallel strips . at additive levels above approximately 100 ppm concentration of 4 - methyl - dbs ( aka , p - methyl - dbs ) the film appeared clear . the film , having been slit into strips , was conveyed across three large rolls into an oven approximately 14 ft long ( set at a temperature given below ) where it was heated and drawn to the draw ratio given below . after leaving the oven , the film strips passed over three rolls , the first two heated by hot oil to a temperatures of 342 ° f . ( 172 - 3 ° c .) with the last roll being unheated . the first of these three rolls has a linear velocity somewhat greater than 500 ft / min , with the difference expressed as the relax percentage , where the relax percentage is the percentage of 500 ft / min that the first roll was running faster than the third , which was running at 500 ft / min . these film strips were then traversed to winders where they were individually wound . these final film strips are thus referred to as the polypropylene tape fibers . several tape fibers were made in this manner , adjusting the concentrated additive - pp mixture level to adjust the final additive level . these tape fibers were tested for tensile properties using an mts sintech 10 / g instrument . an fts - 1000 force shrinkage tester from lawson - hemphill was used to test high temperature shrinkage . the heater temperature was set to 127 ° c ., which gives the same shrinkage measurements as a 5 minute hot air shrinkage at 150 ° c . in a convection oven . all of the shrinkage results are reported in the table below for different nucleator compound levels in different fibers . creep was measured by fixing one end of a tape fiber near the top of a convection oven while suspending a 225 g weight at the other end of the fiber with the oven temperature at 50 ° c . a ten inch length was marked before hanging the weight in the oven , and the length of this originally - ten - inch piece was measured after hanging in the oven at 50 ° c . for 15 hours . the creep is reported as a percentage . the results for each example below are actually the average for four separate trials at the same additive level for each different nucleator . a control formulation was utilized as well without any nucleator present . these formulations were then compounded and formed into yarns through the drawing and heat - setting procedures discussed above . the oven temperatures , draw ratios , and relax ratios for each different set of samples yarns were as follows in table 2 : such yarns were then measured for a variety of different physical characteristics , including denier , peak load , elongation at peak load , fiber tenacity , 1 % secant modulus , 3 % secant modulus , 5 % secant modulus , and , lastly 150 ° c . hot air shrinkage . the results are tabulated for each yarn sample below ( with each measurement actually the mean result for four different yarns produced in the same manner as in the tables above ): the long period spacing of several of the above yarns was tested by small angle x - ray scattering ( saxs ). the small angle x - ray scattering data was collected on a bruker axs ( madison , wis .) hi - star multi - wire detector placed at a distance of 105 cm from the sample in an anton - paar vacuum chamber where the chamber was evacuated to a pressure of not more than 100 mtorr . x - rays ( λ = 1 . 54178 å ) were generated with a macscience rotating anode ( 40 kv , 40 ma ) and focused through three pinholes to a size of 0 . 2 mm . the entire system ( generator , detector , beampath , sample holder , and software ) is commercially available as a single unit from bruker axs . the detector was calibrated per manufacturer recommendation using a sample of silver behenate . a typical data collection was conducted as follows . to prepare the sample , the yarn was wrapped around a 3 mm brass tube with a 2 mm hole drilled in it , and then the tube was placed in an anton - paar vacuum sample chamber on the x - ray equipment such that the yarn was exposed to the x - ray beam through the hole . the path length of the x - ray beam through the sample was between 2 - 3 mm . the sample chamber and beam path was evacuated to less than 100 mtorr and the sample was exposed to the x - ray beam for one hour . two - dimensional data frames were collected by the detector and unwarped automatically by the system software . the data were smoothed within the system software using a 2 - pixel convolution prior to integration . to obtain the intensity scattering data [ i ( q )] as a function of scattering angle [ 2θ ] the data were integrated over λ with the manufacturer &# 39 ; s software set to give a 2θ range of 0 . 20 - 2 . 5 ° in increments of 0 . 01 ° using the method of bin summation . the data was collected upon exposure to such high temperatures for one - half hour , and subtracting the baseline obtained by taking similar data with no tape fiber sample in place . the long period measurements were taken and are tabulated below in nanometers . yarns of the tape fibers above were then woven into a primary carpet backing component for carpet tiles . such tape fibers were made with knives set to cut the tape to different widths , such that yarns of both approximately 1100 and 600 denier measurements were made . the 600 denier yarns were warped at 24 yarns / inch and a full width of about 168 inches . these warped yarns were then woven with the wider , 1100 denier yarns on a rapier loom at approximately 12 picks per inch to provide a backing substrate . upon attachment of such a backing ( 18 inches wide ) to a tufted substrate ( also 18 inches wide ), followed by printing with liquid colorants and dyes of the surface opposite the backing itself , the resultant composite was then exposed to drying temperatures ( about 130 ° c .). the complete composite subsequently exhibited no appreciable modification of the dimensions thereof . a comparative polypropylene tape fiber - containing primary backing exhibited a shrinkage rate of about 4 - 5 %, thereby reducing the dimensions of the comparative tufted substrate / primary backing composite by a similar amount . thus , it is apparent that the inventive tape fibers are substantial improvements over the typical , traditional , state of the art polypropylene tape fibers utilized today . there are , of course , many alternative embodiments and modifications of the present invention which are intended to be included within the spirit and scope of the following claims .