Patent ID: 12240936

EXAMPLES

Briefly, Examples 1 and 2 relate to the preparation of N-diol containing PU polymer, Example 5 relates to the preparation of corresponding quaternised PU polymer. Generally, the preparation processes described, i.e., developed on a laboratory scale, are suitable for being processed to industrial-scale.

Examples 3 and 4 describe the characterisation of N-diol containing PU polymers in regard to molecular mass and decomposition temperature; Example 6 describes the characterisation of quaternised PU polymers.

Examples 7 and 8 make comparisons of N-diol containing PU polymers and elastane in regard to glass transition temperature (Tg) and tensile strength (modulus of elasticity, fracture strain).

Example 9 relates to blends of N-diol containing PU polymers and elastane, and describes their tensile strengths.

Examples 10 and 11 describe the relaxation behaviour of N-diol-containing PU polymers and of blends with elastane, respectively.

In Table 16, characterising features of exemplary polymer samples described and discussed in some of the examples below, are summarized.

Example 1: Preparation of N-Diol

Chemicals

N,N-Dimethylethylendiamine (DMEA): CAS: 108-00-9, Acros, distilled before use; 2-hydroxyethylacrylate (HEA): CAS: 818-61-1, TCI, >95%; THF: technical grade, dried and distilled before use; Et2O: technical grade, dried and distilled before use.

ChemicalM [g·mol−1]n [mol]M [g]D [g·cm−3]V [ml]eq.DMEA88.150.59448.420.807601HEA116.121.099127.571.106115.32THF72.111.2388.90.8891002.1
Procedure

115.3 ml (1.099 mol) HEA and 100 ml THF were taken in a 500 ml 3-neck-round-bottom flask under inert gas (argon) at room temperature (20±2° C.). 60 ml (0.594 mol) DMEA was added to this solution drop-wise. The mixture was stirred at 45° C. in an oil bath for 24 h. After this time, the solvent was removed and the left over (yellowish liquid) was extracted with Et2O (4×100 ml Et2O, product is not soluble in Et2O). The product was dried in vacuum at 50° C.

Yield: 132 g, 75%.

The product was characterised by 1H-NMR spectroscopy.

A reaction scheme is shown inFIG.4.

Example 2: Preparation of Polyurethane (PU) Polymer Containing N-Diol (PU-N)

Chemicals

1,4-Butanediol (BD): CAS: 110-63-4, distilled before use; Poly(THF) 1000: CAS: 25190-60-1, Mn(number average molar mass)=1,000 g/mol, Merck; 4,4′-diphenylmethanediisocyanate (MDI): CAS: 101-68-8, >97%, TCI; dibutyltin dilaurate (DBTL): CAS: 77-58-7, Sigma-Aldrich;

THF: technical grade, dried and distilled before use.

Reaction 1:

ChemicalM [g · mol−1]n [mol]M [g]D [g · cm−3]V [ml]eq.N-Diol (as synthesized320.190.004481.4350.5in Example 1)Poly(THF)1,0000.008968.9611000BD90.120.004480.4041.020.3960.5MDI250.250.018744.691.052.08DBTL631.561.22 · 10−40.0771.0660.07260.5 wt %THF72.110.24717.780.8892027.5
Reaction 2:

ChemicalM [g · mol−1]n [mol]M [g]D [g · cm−3]V [ml]eq.Diol (PH16N-6)320.190.008962.871Poly(THF)1,0000.004484.480.51000BD90.120.004480.4041.020.3960.5MDI250.250.018744.691.052.08DBTL631.560.985 · 10−40.061.0660.05630.5 wt %abs. THF72.110.24717.780.8892027.5
Reaction 3:

ChemicalM [g · mol−1]n [mol]M [g]D [g · cm−3]V [ml]eq.Diol (PH16N-6)320.190.004481.4350.5Poly(THF)10000.004484.480.51000BD90.120.008960.8081.020.7921MDI250.250.018744.691.052.08DBTL631.560.903 · 10−40.0571.0660.05350.5 wt %abs. THF72.110.24717.780.8892027.5
Procedure

MDI and DBTL were mixed with 20 ml dried THF in 100 ml nitrogen flask under argon. The solution was cooled in an ice bath. N-Diol and BD were added dropwise to this cooled solution within 10 min. After addition was finished, the mixture was stirred for 30 min at room temperature. After this, poly(THF) was added dropwise and stirred for further 1 h. Afterwards, the reaction contents were heated at 50° C. (oil bath temperature) for 2 h. Afterwards, the polymer formed was precipitated in MeOH and dried at 50° C. in vacuum. Yield: 89%.

A reaction scheme is shown inFIG.5.

Example 3: Comparison of Different Ratios of Monomers

PU-N synthesis as described in Example 2 was carried out based on ratios of monomers given in Table 1 below.

TABLE 1SampleN-Diol/eq.P(THF)/eq.BD/eq.MDI/eq.PH18N-61001.04(Comp. sample)PH21N-61012.08(Comp. sample)PH15D-60112.08(Comp. sample)PH23N-60.510.52.08PH24N-610.50.52.08PH18J-70.50.512.08eq. = equivalent

Samples containing the PU-N product were analysed by GPC (FIG.7) and TGA (FIG.8).

Gel permeation chromatography (GPC) was used for molar mass determination (instrument: Agilent Technologies 1200 Series/1260 Infinity; column 1: PSS SDV 5 μm 100000; column 2: PSS SDV 5 μm 10000; column 3: PSS SDV 5 μm 1000; column 4: PSS SDV 5 μm 100; detector 1: Waters 486 UV; detector 2: Techlab Shodex RI; eluent: THF; flow rate: 1.0 ml/min; column temperature: 40° C.; calibration standard: polystyrene).

Thermogravimetric analysis (TGA) was used to determine the thermal stability. A Netzsch TG 209 F1 Libra was used. Samples were heated from 25 to 800° C. in Al2O3-pans. Ca. 5-10 mg polymers were measured with a balance and put in a sample-pan. Whole measurement was done under air with a heating rate of 10° C./min. The temperature at which the weight loss started is mentioned as degradation temperature.

As shown inFIG.7, the molecular mass of PU contained in comparison samples PH18N-6 (100% N-diol) and PH21N-6 (50% N-diol, 50% BD) turned out to be too low. The highest molecular mass was shown by comparison sample PH15D-6 (50% P(THF), 50% BD).

Amongst PU-N samples PH24N-6 (50% N-diol, 25% P(THF), 25% BD), PH23N-6 (25% N-diol, 50% P(THF), 25% BD), and PH18J-7 (25% N-diol, 25% P(THF), 50% BD), the molecular mass increased with the amount of P(THF) and BD.

The results to be seen fromFIG.7are summarised in Table 2 below.

TABLE 2SampleMn [g/mol]DPH18N-63.3 · 1031.4PH21N-65.7 · 1031.9PH15D-67.5 · 1041.8PH23N-62.3 · 1032.1PH24N-61.6 · 1032.2PH18J-73.1 · 1032.0Mn = molar mass;D = molecular mass [Da]

As shown inFIG.8, an increased amount of P(THF) or BD resulted in a higher decomposition temperature.

The results to be seen fromFIG.8are summarised in Table 3 below.

TABLE 3Sample5% decomposed [° C.]PH18N-6199PH21N-6219PH15D-6307PH23N-6278PH24N-6213PH18J-7246

Example 4: Comparison of Different Sequences of Addition of Monomers

PU-N synthesis as described in Example 2 was carried out by adding first N-diol+P(THF) and subsequently BD (option 1), or by adding first N-diol+BD and subsequently P(THF) (option 2).

Option 1: PH23N-6, PH24N-6, PH18J-7

(i) MDI+DBTL in abs. THF, cooling down on ice(ii) Adding N-diol+P(THF) (in drops), stirring 30 min at room temperature (iii) Adding BD (in drops)
Option 2: PH12D-6, PH16J-7, PH17J-7(i) MDI+DBTL in abs. THF, cooling down on ice(ii) Adding N-diol+BD (in drops), stirring 30 min at room temperature(iii) Adding P(THF) (in drops)

The ratios of monomers were as given in Table 4 below.

TABLE 4SampleN-Diol/eq.P(THF)/eq.BD/eq.MDI/eq.PH23N-60.510.52.08PH12D-6PH24N-610.50.52.08PH16J-7PH18J-70.50.512.08PH17J-7

Samples containing the PU-N product were analysed by GPC (FIG.9) and TGA (FIG.10).

As shown inFIG.9, addition of P(THF) after BD (option 2) resulted in a higher molar mass.

The results to be seen fromFIG.9are summarised in Table 5 below.

TABLE 5SampleMn [g/mol]DPH23N-62.3 · 1042.1PH12D-64.3 · 1042.1PH24N-61.6 · 1042.2PH16J-73.1 · 1041.7PH18J-73.1 · 1042.0PH17J-74.0 · 1041.6Mn = molar mass; D = molecular mass [Da]

As to be seen fromFIG.10, the sequence of addition of monomers virtually showed no effect on the decomposition temperature.

The results to be seen fromFIG.10are summarised in Table 6 below.

TABLE 6Sample5% Decomposition [° C.]PH23N-6278PH12D-6271PH24N-6213PH16J-7221PH18J-7246PH17J-7251

Example 5: Quaternization of the N-Diol Containing PU Polymer

Chemicals

PU-N (as produced in Example 2); 1-bromobutane: CAS. 105-65-9, Merck, >98%; THF: technical grade, distilled before use.

Reaction

MnMDVChemicals[g · mol−1][mol][g][g · cm−3][ml]PU-N101-Bromobutane137.030.0476.41.285THF72.110.88930
Procedure

10 g PU-N was dissolved in 30 ml THF at 60° C. 5 ml 1-bromobutane was added. The reaction mixture was stirred at 60° C. for different time intervals to change the degree of quaternization. The quaternised polymer was precipitated in hexane and dried at 50° C. in vacuum. Yield: 96%.

The product PU-N+ was characterised by 1H-NMR spectroscopy.

A reaction scheme is shown inFIG.6, andFIG.11further illustrates the principle of quaternization.

The extent of quaternization is exemplarily summarized in Table 7 below.

TABLE 7SamplePUQuaternisation [%]PH06M-7_PH16J-7_PU29PU-N+_24h(50% N-diol, 25%P(THF), 25% BD)PH07M-7_PH17J_PU16PU-N+_24h(25% N-diol, 25%P(THF), 50% BD)PH07F-8_PU-N+(50% N-diol, 25%5P(THF), 25% BD

Example 6: Characterization of the Quaternised PU Polymer (PU-N+)

Samples containing non-quaternised or quaternised PU polymer (i.e., PU-N or PU-N+) were analysed by TGA (FIG.12). As shown, quaternization did not affect the decomposition temperature.

The results to be seen fromFIG.12are summarised in Table 8 below.

TABLE 8Sample5% Decomposition [° C.]PH16J-7_PU221(50% N-diol, 25% P(THF), 25% BD)PH06M-7_PU-N+_24h224(29% quarternized)PH17J-7_PU251(25% N-diol, 25% P(THF), 50% BD)PH07M-7_PU-N+_24h246(16% quaternised)

Example 7: Dynamic-Mechanical Thermoanalysis (DMTA)

Samples containing non-quaternised PU or quaternised PU polymer (i.e., PU-N or PU-N+) were analysed by DMTA; elastane served for comparison (FIGS.13A-13E).

For DMTA, a Rheometric Scientific DMTA instrument was used.

In contrast to elastane (FIG.13A), the PU polymer samples showed glass transition temperatures (Tg) of above 0° C., regardless of whether they were quaternised or not.

As furthermore shown, an increased amount of BD resulted in a higher glass transition temperature (FIG.13B: Tg=40° C.;FIG.13D: Tg=55° C.).

Finally, quaternization of PU-N (resulting in PU-N+) induced an increase in the glass transition temperatures observed with the non-quaternised PU-N (FIG.13C: Tgl=70° C., i.e., >40° C.;

FIG.13E: Tgl=70° C., i.e., >55° C.).

Example 8: Stress-Strain Test

Mechanical properties of the produced PU polymers were tested. For that purpose, samples of non-quaternised PU or quaternised PU polymer (i.e., PU-N or PU-N+) were analysed by a strain-stress test (tensile testing); elastane served for comparison.

For testing, a Zwick/Noell BT1-FR 0.5TN.D14 machine was used (pre-load: 0.01 N/mm test rate: 50 mm/min). Sample preparation: 1 g PU (PU-N or PU-N+) was dissolved in 10 ml HFIP (hexafluoroisopropanol) and dropped on a glass plate for making a film. The film was dried at room temperature for 24 h followed by drying at 45° C. in vacuum for 24 h. The films were cut to the dimensions (W: 5 mm, L: ≥40 mm) for mechanical testing.

As shown inFIGS.14A-14B, PU-N+(FIG.14B) showed a strain behaviour different from that of elastane (FIG.14A).

Furthermore, quaternization induced a decrease in fracture strain, as shown in Table 9 below.

TABLE 9EmodFracture strainSample[MPa]dL [%]Ratio of monomersElastane2.43,403PH15D-6_PU12.51,56650% P(THF), 50% BDPH16J-7_PU371,38850% N-Diol, 25% P(THF),25% BDPH06M-7_PU-N+15479650% N-Diol, 25% P(THF),25% BD 29% quaternisationPH17J-7_PU951,02525% N-Diol, 25% P(THF),50% BDPH07M-7_PU-N+9878025% N-Diol, 25% P(THF),50% BD 16% quaternisationEmod= modulus of elasticity; dL = delta length; % = weight %; film thickness: 180 ± 20 μm

Example 9: PU Polymer/Elastane Blends

The produced PU polymers were blended with elastane (commercially available). Mechanical properties were tested using a strain-stress test as described in Example 8.

As shown inFIGS.15A-15B, a blend of 70% PU-N+ and 30% elastane (FIG.15B) showed a strain behaviour different from that of elastane (FIG.15A).

Furthermore, fracture strain and modulus of elasticity measured with different PU-N+/elastane blends are given in Table 10 below.

TABLE 10EmodFracture strainSample[MPa]dL [%]Ratio of monomersElastane2.43,403PH06M-7_PU-N+15479650% N-Diol, 25% P(THF),25% BD 29% quaternisedPH07M-7_PU-N+9878025% N-Diol, 25% P(THF),50% BD 29% quaternisedBlend_10%3.43,04410% PH06M-7_PU-N++PH06M-7_PU-N+90% elastaneBlend_30%7.12,41330% PH06M-7_PU-N++PH06M-7_PU-N+70% elastaneBlend_50%151,60150% PH06M-7_PU-N++PH06M-7_PU-N+50 elastaneBlend_70%311,09770% PH06M-7_PU-N++PH06M-7_PU-N+30% elastaneBlend_10%3.43,06010% PH07M-7_PU-N++PH07M-7_PU-N+90% elastaneBlend_30%62,33130% PH07M-7_PU-N++PH07M-7_PU-N+70% elastaneBlend_50%141,71050% PH07M-7_PU-N++PH07M-7_PU-N+50% elastaneBlend_70%391,30170% PH07M-7_PU-N++PH07M-7_PU-N+30% elastaneEmod= modulus of elasticity; dL = delta length; % = weight %; film thickness: 160 ± 20 μm

For comparison, fracture strain and modulus of elasticity measured with different PU-N (i.e., non-quaternised)/elastane blends are given in Table 11 below.

TABLE 11EmodFracture strainSample[MPa]dL [%]Ratio of monomersPH02M-7_PU50% N-Diol, 25% P(THF),25% BDBlend_10%3.73,26210% PH02M-7_PU +PH02M-7_PU90% elastaneBlend_30%5.22,90030% PH02M-7_PU +PH02M-7_PU70% elastaneBlend_50%5.52,32550% PH02M-7_PU-N +PH02M-7_PU50% elastaneBlend_70%6.82,49270% PH02M-7_PU-N +PH02M-7_PU30% elastaneBlend_90%8.81,54490% PH02M-7_PU-N +PH02M-7_PU10% elastaneEmod= modulus of elasticity; delta length; % = weight %; film thickness: 140 ± 10 μm

Example 10: Relaxation Behaviour

A sample of non-quaternised PU (PU-N) or of corresponding quaternised PU (PU-N+), 29% quaternization, was stretched from 10 mm (original sample length) to 40 mm (FIGS.16A, and16B). Upon release, both samples recovered their original sample lengths in about 6 hours. In doing so, approximately 180% recovery was achieved in about 5 min, after which the remaining 120% was recovered much more slowly. In this respect, the relaxation behaviour of PU-N and PU-N+ was almost the same.

Similarly, samples of PU-N+ having different degrees of quaternization, namely 9% or 5%, were stretched from 10 mm to 50 mm (FIGS.16C, and16D). Upon release, 300% and 280% of the original sample length was recovered immediately, and further 140% and 160% was recovered after 5 min, respectively. Thus, approximately 90% total recovery was achieved within about 5 min.

Thus, the relaxation behaviour depends, at least partially, on the degree of quaternization.

The results to be seen fromFIGS.16A-16Dare summarized in Table 12 below.

TABLE 12ImmediateRelaxation 1Relaxation 2Ratio ofSamplerelax. [%][%/time][%/time]monomersPH16J-7_PU10080/5min120/6h50% N-diol,25% P(THF),25% BDPH06M-7_80100/5min120/6h50% N-diol,PU-N+25% P(THF),(derived from25% BD 29%PH16J-7_PUquaternisationPH23M-7_300140/5min60/60min50% N-diol,PU-N+25% P(THF),(derived from25% BD 9%PH02M-7_PU)quaternisationPH30M-7_280160/5min60/60min50% N-diol,PU-N+25% P(THF),(derived from25% BD 5%PH02M-7_PU)quaternisation

Example 11: Relaxation Behaviour of PU Polymer/Elastane Blends

Non-quaternised PU (PU-N) or corresponding quaternised PU (PU-N+) having different degrees of quaternization (29%, 9% or 5%) were blended with elastane (commercially available), respectively. Samples were subjected to stretching-and-release similar to the description in Example 10 (stretching of samples from 10 to 50 mm).

The results are summarized in Tables 13 to 15 below.

TABLE 13Blends of PU-N (PH02M-7_PU; 50% N-diol, 25% P(THF), 25% BD)and elastane.ImmediatePU-NElastanerelaxationRelaxation 1Relaxation 2[wt %][wt %][%][%/time][%/time]109045030/5 min20/10-20min307043040/5 min30/10-20min505042050/5 min30/2h703041060/5 min30/3h901039080/5 min30/6h

Firstly, admixture of elastane to PU-N altered the relaxation behaviour of the individual PU-N and of elastane.

As to be seen from Table 13, the blends showed approximately 80 to 90% total recovery immediately after release, depending on the relative amounts of PU-N and elastane. Recovery of the remaining 10 to 20% took about 15 min to 6 hours, also depending on the relative amounts of PU-N and elastane. More generally, increased relative amounts of PU-N resulted in an increase in total relaxation time.

TABLE 14Blends of PU-N+, 29% quaternisation (PH06M-7_PU-N+;50% N-diol, 25% P(THF), 25% BD) and elastane.ImmediatePU-N+ElastanerelaxationRelaxation 1Relaxation 2[wt %][wt %][%][%/time][%/time]109044020/5 min40/30-60min307040040/5 min60/2h5050340100/5 min60/3h7030280120/5 min100/6h

As to be seen from Table 14, increased relative amounts of PU-N+ resulted in an increase of total relaxation time. Furthermore, compared to non-quaternised PU-N (Table 13), PU-N+ was associated with increased total relaxation times. Apart from that, PU-N+ with a high degree of quaternization (29%) does not provide any particular advantage over non-quaternised PU-N when used in blends with elastane.

TABLE 15Blends of PU-N+, 9% quaternisation (PH23M-7_PU-N+; 50%N-diol, 25% P(THF), 25% BD) and elastane.ImmediatePU-N+ElastanerelaxationRelaxation 1Relaxation 2[wt %][wt %][%][%/time][%/time]505039080/5 min30/30-60 min6040350100/5 min50/30-60 min703038090/5 min30/30-60 min

As to be seen from Table 15, blends with PU-N+ having a lower degree of quaternization (here: 9%) showed relaxation times of about 30 min to 1 h for all tested compositions. Apart from that, the relaxation behaviour is very similar to that of blends with non-quaternised PU-N, i.e., approximately 80% total recovery was achieved immediately.

TABLE 16Blends of PU-N+, 5% quaternisation (PH30M-7_PU-N+; 50% N-diol,25% P(THF), 25% BD) and elastane.ImmediatePU-N+ElastanerelaxationRelaxation 1Relaxation 2[wt %][wt %][%][%/time][%/time]505039070/5 min40/30-60 min604038080/5 min40/30-60 min703038080/5 min40/30-60 min

As to be seen from Table 16, the relaxation behaviour of blends with PU-N+ having a low degree of quaternization (here: 5%) is very similar to that of blends with PU-N+, 9% quaternization (Table 15), and of non-quaternised PU-N (Table 13).

TABLE 17Tgor Tg1/Tg2DegradationdL [%]N-Diol:Degree ofNumber average[° C.]temperature(pre-load: 0.01P(THF):BDquaternisationmolar mass Mn(from[° C.]EmodN/mm; speed:Sample(molar ratio)[%][g/mol]DMTA)(from TGA)[MPa]σM[MPa]50 mm/min)Elastane07.54 · 104−502432.4273,403PH15D-6_PU0:1:103.06 · 104−2523012.5331,566PH16J-7_PU1:0.5:0.504018537351,388PH06M-7_PU-1:0.5:0.524 h/29%40/7018215442796N+(derived fromPH16J-7_PU)PH23M-7_PU-1:0.5:0.590 min/9%2912968N+(derived fromPH02M-7_PU)PH30M-7_PU-1:0.5:0.545 min/5%12111,056N+(derived fromPHO2M-7_PU)Blend4193,08230% PH16J-7_PU +70% elastaneBlend4.9192,62950% PH16J-7_PU +50% elastaneBlend5.9162,41270% PH16J-7_PU +30% elastaneBlend3.7283,26210% PH02M-7_PU +90% elastaneBlend5.2282,90030% PH02M-7_PU +70% elastaneBlend5.5202,32550% PH02M-7_PU +50% elastaneBlend6.8212,49270% PH02M-7_PU +30% elastaneBlend8.8161,54490% PH02M-7_PU +10% elastaneBlend6.3151,89650% PH23M-7_PU-N+ +50% elastaneBlend9.9182,06760% PH23M-7_PU-N+ +40% elastaneBlend10.5151,99070% PH23M-7_PU-N+ +30% elastaneBlend_6.2141,80050% PH30M-7_PU-N+ +50% elastaneBlend7.2162,18760% PH30M-7_PU-N+ +40% elastaneBlend8.8131,95170% PH30M-7_PU-N+ +30% elastane

Example 12: Polymer Fibres/Filaments

A sample of quaternised PU polymer (PU-N+) (PH07F-8_PU-N+=−50% N-Diol, 25% P(THF)25% BD, 5% quaternised (5% N+)) was milled to a powder using an ultra-centrifugal mill ZM200. The milling machine had a sieve with pore diameter of 1 mm. Machine with any other pore diameter can also be used and sieve diameter is not important. Idea was to convert a mass of the polymer into a powder that can be easily fed to extruder for making filaments. Thereafter it was spun as a mono-filament using a twin screw extruder (process11from Thermo Scientific). The extruding filaments were continuingly passed through a trough having SiO2 powder to prevent any residual stickiness/tackiness of the filament and allowed storage of the filament, when it has been wound up into a roll without sticking to each other). Using this set up, the melt spinning of the PU ionomer into a mono-filament is easy, and a large scale production is possible.

An exemplary microscopical image of such filament is shown inFIG.17(500× magnification). The filaments are not transparent and have an opaque surface.

Mechanical properties of the spun filament were tested. For that purpose, the produced filament(s) were analyzed by a strain-stress test (tensile testing). For testing, a Zwick/Noell BT1FR0.5TN.D14 machine was as used. (Preload: 0.1 kPa, test rate: 50 mm/min). The filament had a diameter of 280+/−30 and the filament was subjected to tensile testing

The following results were achieved:

Emod/Fracture strainF (max)/SampleMPadL [%]MPaMonomer ratioPH07F-8_PU-2.511002950% N-Diol,N+_filament_with25% P(THF),SiO2powder25% BD, 5% N+Emod= modulus of elasticity; dL = delta length; % = weight percent; filament diameter = 208 +− 30 μm

The results of the strain-stress test are shown inFIG.18.

The relaxation behavior of such filaments is shown inFIG.19. For such relaxation behavior, a filament of quaternised polyurethane polymer was stretched from 10 mm (original filament length) to 50 mm. Upon release, the filament recovered its original sample length in approximately 35-65 min.

In summary, in this example, the inventors have shown that polyurethane-ionomer can be reproducibly spun into filaments the tackiness of which can be prevented by dusting with SiO2-powder or a similar powder or a suitable oil. The powder does not interfere with the relaxation behavior.