R.E. Whitfield

Wool Fabric Stabilization by Interfacial Polymerization. Part I: Polyamides

A new technique is presented for making wool fabrics shrink resistant. Through interfacial polymerization polyamides, e.g., poly (hexamethylene sebacamide), are formed on the surface of the textile fibers. Fabric is padded consecutively through an aqueous solution of a diamine and a water-immiscible solution of a diacid chloride. Polymeriza tion is extremely rapid and no heating or curing is required. Following the two-step padding, the fabric is simply washed and dried. Less than 5% resin on the fabric is required for dimensional stability in laundering. The wool fabrics treated are essentially unchanged in hand, flexural rigidity, break strength, percent elongation, and chemical resistance; they are improved in wrinkle recovery and smoothness after tumble drying.

Wool Fabric Stabilization by Interfacial Polymerization: Part III: Polyurethanes

A single-station machine on which a fiber can be fatigued in a localized region, by being axially rotated in a bent configuration, has been built. The test fiber, on either side of the bend, is mounted on shafts at 90° to each other, driven at the same rotary speed. Speeds up to 550 rpm are attainable. Nylon 66 and nylon 6 monofils in a number of diameters from 8 to 28 mils have been fatigued in biaxial rotation on this machine, in a fourfold range of rotary velocities and for periods of 15, 30, and 45 min. They were then tested for residual breaking tenacity and extension. A few fibers have been fatigued for other periods of time, or to rupture, for microscopic examination of the fatigued region. In most samples the rupture properties decrease with increasing rotary velocity, for any given fatiguing period. The rate of this decrease tends to be lower in the range of higher velocities. The shapes of the breaking-extension curves are largely determined by those of the breaking-tenacity curves, reflecting the near-linearity of the tenacityextension relationship. The monofils of smaller diameter, especially those of nylon 6, are less affected by the increase in rotary velocity. In most of the samples, the residual breaking tenacity appears to be largely determined by the total number of revolutions sustained by the specimen, with no consistent influence of rotary velocity on the results. Monofils of the higher draw ratios and those that had been heat-set show a much sharper decline in residual properties with increasing rotary velocity than do the nonheat-set samples of lower draw ratio. However, the breaking tenacities of the heat-set samples retain their relatively higher positions after fatiguing under most conditions. Representative photomicrographs of monofils fatigued at various velocities and for different periods short of rupture show progressive development of diagonal fissures in the fatigued regions, especially in the nylon 66, and of a bulbous expansion in the nylon 6 specimens. Photomicrographs of the broken ends of monofils fatigued to rupture indicate that the breakage in nylon 6 occurs across planes coinciding with the diagonal fissures. In nylon 66 the breakage appears to occur in a roughly transverse plane. IN THH general introduction to this series 131 it was indicated that the second of the two types of fatiguing strain to which model fibers would he suhjeeteci was compression-extension. It did not appear to he experimentany feasil>le to put a long section of fiber into cyclic compression. Recourse would have to le taken to some action like bending, which would impose a compressive stress on the test nher over a 1 A project sponsored by a group of member companies of Textile Research Institute.

Reactive Polymer Finishes for Wool. III. Phase Boundary Cross-Linking of Polyethylene Derivatives

Textile finishing by means of phase-boundary ..limited cross-linking (PBLC) of reactive polymers ( 13 and the general scope and utility of the method 111,. 7} liave been reported. The present paper explores in ~l1ore detail the utility of reactive polyethylene derivatives in phase-boundary limited cross<-’linking systems. The study also ittcltules extensive characterization of the textile properties of treated wool and characterization of the polymer wool etitity. . ’

Wool Stabilization by Interfacial Polymerization Part VIII: Location and Nature of the Polymer

Poly(hexamethylene sehacamide) formed on the surface of wool by interfacial poly condensation appears to be grafted to the wool. The ultra-thin film of the polymer is not extracted by good solvents. If the grafting sites on the wool are blocked by acetylation prior to the interfacial polymerization, the surface, film is easily extracted with good solvents and the treated wool has no shrink resistance. Application of pre formed poly (hexaniethyelne sebacamide) from solution, followed by evaporation of the solvent imparts little or no shrink resistance to the wool, and the surface film so formed is easily extracted with good solvents. About 1% to 2% polymer can be grafted to the wool surface by interfacial polycondensation ; polymer in excess of this amount is only partially grafted. With suitable enzymes to eat away the wool from a treated wool sample, the grafted coatings have been isolated and characterized. The grafting sites in the wool have been shown to be the free amino groups of N-terminal amino acids and amino and hydroxyl groups of side chains in the wool proteins.

Wool Stabilization by Interfacial Polymerization: Part IV: Polyureas, Polyesters, Polycarbonates, and Further Studies on Polyamides

’ Potassium permanganate in water confers shrink resistance on WOO] fabric, the degree of initial shrink resistance increasing with addition of inorganic salts. On extended severe washing, fabrics treated in higher salt concentrations felt at a greater rate, once the initial period of shrink resistance has passed, than do fabrics treated in low salt concentrations. On the basis of these observations a theory of felting shrinkage is proposed which defines felting behavior of treated wool in terms of cuticle and cortex modification. Cortex modification need only be in the outer layers. Shrink resistance conferred by cuticle modification is characterized by an initial period during which no felting shrinkage takes place, followed by felting at a rate similar to that of untreated wool. Permanganate in saturated salt is an example of such a cuticle treatment. Shrink resistance conferred by outer cortex modification is not achieved by a shrink resist induction period, but by a reduced rate of felting shrinkage. Examples of shrinkproofing treatments resulting in outer cortex modification are : permanganate in water ; dry, acid, and alkaline chlorinations ; and the additional shrink resistance, following permanganate oxidation, conferred by residue times in bisulfite beyond that necessary to clear manganese dioxide. In permanganate treatments followed by reductive clearing, the major portion of shrink resistance is imparted during the oxidation stage for treatments in saturated salt, and during the clearing stage for treaments in water.

Wool Treatment with Reactive Polyethylene Finishes

A study of the properties and application of reactive polyethylene finishes to wool fabric is reported. The reactive finishes are either copolymers of methacryloyl chloride and ethylene or terpolymers of ethylene, methacryloyl, and vinyl acetate. The polymer is applied to the wool in an organic solvent by either a dip-pad-cure method or by an exhaustion procedure. Several textile properties of the treated wool are reported and discussed. The treatment reduces felting shrilkage during machine laundering ; increases the fabric’s resistance to acids, alkalis, or oxidizing solutions; and strengthens the fabric against breaking and abrasion.

Wool Stabilization by Interfacial Polymerization. Part VI: Relative Rates of Hydrolysis of Acid Chlorides

T o disclose any systenlatic effect due to fading, the 318 values for percent paracortex were divided into an E ~ r l y group and a Late group. Tlie F-test (based on variance ratio) and the t-test (based on means and variances) were used to decide the significance or otherwise of differences between the variances of the groups and the differences between their means, respectively. The results are summarized in Table 11. The values were then divided into Good, Poor, Blurred, and Dark groups, and the same tests for sicificance carried out. These results are given in Table 111. I n this case it was found that significant differences a t the 5% level existed between both variances and means for the pairs of groups: Good-Poor, Good-Blurred, GoodTABLE 111. The Effect of Subjective Selection of Fiberr on the Measured Value of Percent Paracortex

Reactive Polymer Finishes for Wool Part IV: Phase Boundary Limited Cross-Linking of Reactive Polyesters and Polyethers to Yield Polyurethanes

A study of the application of several reactive urethane elastomer finishes [based on polyesters or polyethers] to wool is reported. The polymer is applied to the wool in an organic solvent and cross-linked by a diamine applied separately in aqueous solution. Several textile properties of the treated wool are reported. The treated wool has good resistance to felting shrinkage during machine laundering with little or no alteration in the desirable physical and textile properties of the wool.

Textile Finishing: Phase Boundary Limited Cross-Linking of Reactive Polymers

()))<&dquo;) 2 min : olï t&dquo;)’ min ( ) 11 i ( I I’ min : <’)))<’r!0)))i)) On to) ](I 111 ill: <>li I<>r 11) iiiiii A steady state appeared to be reached by the end of each &dquo;off&dquo; period, and thetma1<)eformationBBassuhstantiatty unchanged even after a further 11)-tttin boding. The deformations ;vt the ends o) successive on otYcyctes were therefore taken as &dquo;permanent viscous deiormatiolb; the:-.e 1)1()tte(i ill Figure 2. The dl’Ïol&dquo;matio11 inlTea:-.e~ curBi)inear)y witlt time. hut if the force(1(.fol-lll;ttl4)11 curve of &dquo;Figure 1 i.. u:-.ed to c’)!ivert deformation liito it is found that the elective vi~co--itB in each ra~e IN r011~tant throug&dquo;hout tlte tua. Xative nhers are highly . cmntltrr:·~·ci hy this treatment. and tttirr m·rml~irul examination after tea ~hoBB’~ the presence of &dquo;t1at-<&dquo; on the r~natln-e..e,l surfaces. Siiigl« l’xpl’ril11ent... il1u:-.trated hy 1-’Igiii-c 2. indicatl’el that tlte illt1ul’nl’l’ oi ;lcid and oi iormaldehyde pretreatn1l’nt i. to reduce tltr deformation, i.e..to increase the lateral viscosity at 11111&dquo; (’. Both oi tlll’’’l’ t.reatn1l’nb reduce tIlt’ ettectiBeness of p)eatinjn operations on woo) fabrics. although 11Ime dramatically than BBould he expected on the hasis of the present r~·.ult·. The Iitei-;tl B’i:-.co..ity oi Ilatin> ill w;ttcr wa· found to increase rapidly as the temperature decreased. In separate experiments witlt different hatches of 111)(.’1&dquo; it BBas found that the viscosity at 71)° C Bvas over twenty tinBe:, the It lOW {-. Thi~ i~ again in !,eiiii(iii;iiitit.,ItlB,e agreement with I;il>11<~-j>le;itiiig tests. It may he concluded that lateral compression is a possihte mechanism operating in setting processes in woo) fabrics. ,

Stabilization of Wool Fabric by Interfacial Polymerization: Western Regional Research Laboratory Albany 10, California October 12, 1960

interfacial polymerization is extremely rapid and no heating or curing is required. Following the twostep padding, the fabric is simply washed and dried. Less than 5’~ polymer on the fabric is required for dimensional stability in laundering. The treated fabrics are essentially unchanged in hand, flexural rigidity, break strength, percent elongation, and chemical resistance; they are improved in wrinklerecovery and smoothness after tumble drying. Typi-