Struktura fazowa i właściwości fizyczne mieszanin

• Autorzy: Haponiuk J.T.
• Języki publikacji: PL

Abstrakty

PL

Zbadano właściwości nowych układów polimerowych - mieszanin poli(E-kaprolaktamu) - poliamidu 6 z termoplastycznymi elastomerami poliuretanowymi lub z semikrystalicznym kopolimerem kwas -hydroksymasłowy/kwf -hydroksywalerianowy (kopolimer HB/HV), będącym plastomerem. Wymienione polimery, zastosowane w mieszaninach z poliamidem 6, mają grupy funkcyjne, zdolne do oddziaływań międzycząsteczkowych z grupami amidowymi. Mieszaniny polimerowe przedstawione w pracy nie były dotychczas przedmiotem badań innych autorów. Prognoza mieszalności badanych układów, przeprowadzona na podstawie wyliczeń parametrów rozpuszczalności i napięcia powierzchniowego, pozwoliła na uszeregowanie badanych mieszanin pod względem możliwych oddziaływań międzyfazowych i znalazła potwierdzenie w przeprowadzonych badaniach. Kompatybilność mieszanin termoplastycznych poliuretanów i poliamidu 6 wynika z adhezji międzyfazowej, stwierdzonej w badaniach właściwości wytrzymałościowych i poprzez badania wytrzymałości spoin wtryskowych. Badania przeprowadzone metodą analizy termicznej dynamicznych właściwości mechanicznych (DMTA) wykazały rozproszenie fazy termoplastycznych poliuretanów w matrycy poliamidu 6, ze wskazaniem na słabe oddziaływania fazy rozproszonej z matrycą w przypadku poliuretanu mąjącego poliestrowe segmenty elastyczne. Przebadano wpływ ilości i rodząju poliuretanu w mieszaninach z poliamidem 6 na przebieg topnienia i krystalizacji oraz równowagową temperaturę topnienia fazy krystalicznego poliamidu. W celu modyfikacji oddziaływań międzyfazowych w mieszaninach poliamidu 6 z termoplastycznym poliuretanem zastosowano dodatek syntezowanych blokowych kopoliamidouretanów. Badania przemian fazowych mieszanin poliamidu 6 z termoplastycznym poliuretanem, kompatybilizowanych przy użyciu otrzymanych kopoliamidouretanów, wykazywały obniżenie temperatury zeszklenia fazy poliamidu 6 w mieszaninach, w porównaniu do temperatury zeszklenia czystego poliamidu, co wskazuje na częściową mieszalność w fazie amorficznej. Zcharakteryzowano mieszaniny poliamidu 6 z kopolimerem HB/HV na podstawie wyników badań właściwości \termicznych i dynamicznych właściwości mechanicznych oraz badań elektronomikroskopowych. W tych mieszaninach stwierdzono występowanie wyraźnie odseparowanych faz amorficznych i wykształconych faz krystalicznych obu komponentów.

EN

In this work new blends of polY(E-caprolactam) (Polyamide 6) with elastomers (thermoplastic polyurethane elastomers) and plastics (poly(l3-hydroxybutyrate-co-l3-hydroxyvalerate" were investigated. Thermoplastic polyurethane elastomers are a group of polymers of versatile properties. The possibility of designing their chemical and physical structure facilitates applications of these polymers as blend components. As seen from the solubility parameter difference (Table 7), miscibility of pol yamide 6 could occur more likely with bard segments of the thermoplastic polyamide (BT-MDI), than with the soft segments (PCL-MDI), but it should be rather restricted while the polyurethane bard segments and polyamide 6 crystallise on cooling. The soft segments PCL-MDI of the polyurethane seem to be hardly miscible with polyamide 6. Due to existing dipole-dipole and hydro gen bonding interactions between polyamide 6 and the thermoplastic polyurethane, same degree of compatibility is present, which was expected to be enhanced by the incorporation of polyamideurethanes juto the blend compositions, since the polyamideurethanes contain blocks of the same chemical structure, as the blend components. Poly(l3-hydroxybutyrate-co-l3-hydroxyvalerate), copolymer HB/HV, obtained by bacterial biosynthesis and known as 'Biopol' is a completely biodegradable polymer, which mechanical pro perties are close to the properties of polyolefines. The aim of this wark was investigation of phase transitions of the crystalline phases present in the blends of copolymer HB/HV and polyamide 6 in relation to the phase transitions of the pure components. In hillary blends of polyamide 6 (commercial product, Stilamid S-25 [rom Zakłady Włókien Chemicznych "Stilon") with thermoplastic polyurethane elastomers (TPU) twa types of TPU were used. The pofyether polyurethane (TPU-ET) was obtained by the prepolymer method from 4,4'diisocynate diphenylmethane and 1,4-butanediol and poly(caprolactone)diol. The polyester polyurethane (TPU-ES) was also obtained obtained by the prepolymer method fi'om 4,4'-diisocynate diphenylmethane and l,4-butanediol with poly(ethylene, butylene)adipate as the polydiol component. The bard segment content of the polyurethanes was calculated as 40 wt. %. The blends containing from 2,5 wt. % to 22.5 wt. % of TPU were prepared by compounding in a twin-screw Brabender Plasticorder mixer at 230°e. The blends were then palletised and injection moulded juto plates from which test specimens were cut. The presence of interfacial adhesion in the blends of polyamide 6 with thermoplastic polyurethane elastomers was proved by comparing or the yield stres s or the blends with calculated upper and lower values of yield stress for the cases of strong interfacial adhesion and of lack of interfacial adhesion. The experimental values of yield stress of the blen s were between the two extremes, but the results for PA6/TPU-ES blends were more elosely to ealeulated values for strong interfacial adhesion, then the results for PA6ITPU-ET blends, indieating heller interfaeial adhesion for polyurethanes eontaining polyester sof t segments (Fig. 2 and 3). The presenee ofrelatively strong interfacial adhesion was also eonfirmed by measurements of the tensile strength of the weld lines obtained by injeetion moulding, when the mould was halffilled by a TPU plate and then PA6 was injeeted (Table 9). The blends or polyamide 6 with thermoplastic polyurethane elastomers TPU-ES and TPU-ET were eharaeterised by thermal analysis teehniques, Dynamie Meehanical Thermal Analysis (DMTA) and Differential Seanning Calorimetry (DSC). The stale of the amorphous phase of the blends was seen from the DMT A results. The temperature dependeneies of the lass tangent (tan o) and dynamie storage modulus (E') for TPU-ES and TPUET are shown in the Fig. 6. The analogous dependencies for the polyamide 6 are shown in Fig. 7. The peak of a relaxation of the polyether soft segments was found at -43, I oC (TPU-ET) and of the polyester soft segments at -4,9°C (TPU-ES). The storage modulus for both polyurethanes drops by three deeades at passing through the glass temperature region. For polyamide 6 the peak of a relaxation was found at 49,2°C and at -46,8°C of the 13 relaxation, the latter attributed to amide groups involved in week hydrogen bonds. The peaks for the a relaxation of the blends, as shown in the Fig. 8 and 9 oeeurred elosely to the peak of a relaxation o(polyamide 6 and their position was not dependent rrom the eomposition of the blends. The tan o temperature dependeneies for PA6ITPU-ES blends almost overlap, espeeially when shown together with the tan o profile with a high loss peak for the polyurethane elastomer TPU-ES. In the PA6ITPU-ET blends the tan o values for the blends eontaining 17.5 wt. % and 20 wt. % were in the whole temperature region higher, then for the pure polyamide and then for eompositions eontaining less polyurethane, as seen in the Fig. 9. Figures 10 and 11 indieate next differenees between blends obtained with polyurethanes eontaining polyester or polyether sof t segments, observed in the range of the 13 relaxation of polyamide 6. For PA6/TPU-ES blends the shape and temperature position of the tan O peaks in the polyamide 13 relaxation region are dependent erom the eomposition of the blends. The ehanges may indicate eomposition dependent hydrogen bonding between amide groups of the polyamide and ester groups from the polyester soft segments. This effeet is not visible in ease or polyurethane eontaining less eompatible polyether soft segment s In the ease of PA6ITPU-ET blends the position of the broad tan o peaks in the polyamide 13 relaxalian region is not influeneed by the blend' s eomposition. Beeause the glass temperature transition (tan O maximum) of the blends was not dependent erom the eomposition and no distinet glass transition for separated polyurethane soft segment was visible the blends seem to be multiphase systems, where the elastomerie polyurethane phase is dispersed in a eontinuous polyamide phase. The erystalline phase of the blends was eharaeterised by DSc. From onset temperature of the erystaIlisation it is seen, that the nueleation is slightly retarded in blends with thermoplastie polyurethane elastomers. The temperature at the onset of erystallisation for blends containing more than 7.5 Wt% of the TPU-ES was found to be almost independent of the blend eomposition. The erystallisalian enthalpy per gram of P A6 in the blend, for eompositions up to 10 wt. % or TPU-ES deereased, then, for higher eontents of the polyurethane inereased, but did not reaeh the value estimated for pure polyamide (Table 10). Onset temperature of the erystallisation or P A6/TPU-ET blends was less influeneed, but for TPU-ET contents higher than 15% erystaIlinity degree of the polyamide 6 in the blends is higher than in the pure polyamide, what is a sign of inereasing mobili ty or the polyamide segments in the presenee of molten polyurethane (Table I 1). There was no eomposition dependenee of the melting. The position of the melting peaks of PA6/TPU-ES and PA6ITPU-ET blends ehanges within 2°C, what is a result of differenees in the erystallites dimensions (TabIes 12 and 13). Equilibrium melting temperatures of the PA6ITPU-ES blends are laweT, than for pure polyamide 6, but a elear dependeney on the overall blend eomposition was not observed (Table 14). Copolymers build of PolY(E-eaprolaetam) and POlY(E-caprolaeton)urethane bloeks were synthesised (Table 15), eharaeterised by therma] analysis methods (Figs. 14 - 21) and their suitability as eompatibilizers for blends of PA6 and TPU was investigated. Thermoplastie polyurethane elastomer (TPU-K) was synthesised erom POlY(E-caprolactone)diol, 4,4'-diisocyanate diphenylmethane and 1,4butanediol as the chain extender. At application as compatibilizers of block copolyamideurethanes with the content of polyamide blocks in the range erom 40 wt. % to 90 wt. % blends were obtained, which showed considerable shifts of the lass tangent reak position in relation to pure polyamide 6. (Table 19). The greatest reak temperature shift was observed for the blend containing 25 wt. % TPU, 70 wt. % P A6 and 5 wt. % of the A U90 copolyamideurethane with the temperature position of the reak at 48,8°c. The values of the tan8 estimated at a transition maxims indicate that the damping increases generally with the increase of the TPU content in the blends. The non-isothermal crystallisation temperature of the polyamide phase was lowered in the presence of the polyurethane and the copolyamideurethane (Table 20). Almost in all cases shift to the lower temperatures of the on set of the crystallisation and of the crystallisation reak was observed. The delaying of the crystallisation of the polyamide phase was greater at higher TPU contents in the blends. It was not found that the changes in copolyamideurethane composition produced regular changes in the crystallisation of the blends. The ca1culated solubility parameter differences (Tab le 7) allow the assumption of partial miscibility in the molten stale. Therefore this result may be explained by the diluting effect of the polyurethane, influencing the primary nucleation process. At the DMT A investigations 10ss tangent reak for the glass transition of the separated TPU phase was not visible. Therefore in the investigated blends the polyurethane is dispersed in the polyamide amorphous phase. The copolyamideurethanes were able to act as compatibilizers in the examined systems. The influence of the compatibilizer was evident but not exactly composition dependent, indicating possible differences in the dispersion grade of the TPU in the polyamide matrix. Investigations of the crystallisation kinetics of compatibilised blends (Tabies 22-25) revealed that the half-time of crystallisation is influenced by the copolyamideurethane composition, but is not influenced by the thermoplastic polyuretane content in the blends, what mig t be explained by the interactions of the copolyamides with the crystalline phase of the blends. Another kind of new blends containing poly(f3-hydroxybutyrate-co-hydroxyvalerate), copolymer HB/HV, with 12 wt. % hydroxyvalerate content (Biopol D6000) and polyamide 6 of the 50/50, 60/40, 70/30, 80/20, 90/1 O ratios by weight of polyamide 6 to copolymer HB/HV were obtained by double processing in a single screw laboratory extruder of Brabender Plastograph. The blends reveal in DSC investigations multiphase structure with a distinct crystalline polyamide 6 phase. Due to rapid crystallisation of the polyamide 6 the crystallisation of the copolymer HB/HV is retarded. The grade of crystallisation of copolymer HB/HV is lower in the blends than in the pure stale, as ca1culated from the melting enthalpies. Crystallisation of polyamide 6 in the blends is faster and results in increasing of the grade of crystallisation of polyamide 6 phase comparing to the unblended component. The parameters of the melting endotherms of the polyamide 6 blends/copolymer HB/HV, obtained at the 1st and 2nd heating runs and the parameters of the crystallisation exotherms are presented in the Table 26. The melting and crystallisation peaks occur in the temperature ranges close to the temperature positions of the pure components. For this reason the phase transition were assigned to the separated crystalline phases of the components and the transitions enthalpies were recalculated in the Table 26 in relation to the blend's weight compositions. The melting temperature of the crystalline copolymer HB/HV is characterised in the Table 26 by twa extreme temperatures of the double reak. The melting temperatures of the copolymer HB/HV crystalline phase in the blends are generally lower than the melting temperature of the pure copolymer. Melting enthalpies of the copolymer crystalline phase in the blends are lower than melting enthalpies of the crystalline phase of pure copolymer HB/HV. Maxims of the crystallisation reak of the P A6 phase in the blends appear at higher temperatures as for pure polyamide. The shift to higher temperatures is greater for smaller polyamide content in the blends. Crystallisation enthalpies of polyamide phase in the blends are higher than the crystallisation enthalpy of pure polyamide 6. The non-isothermal crystallisation of the polyamide 6 phase bas been facilitated by the presence of the copolymer HB/HV. Thermal properties of the investigated immiscible, partially crystalline blends revea! therefore noticeable reciproca! influence of the components. The investigated by means of DMTA temperature dependenee of dynamie storage modulus E' (Fig. 32), dynamie lass modulus E" (Fig. 33) and lass tangent lanO (Fig. 34) ofblends obtained from polyamide 6 and the eopolymer HB/HV indieated, that the dynamie meehanieal properties of the blends eontaining up to 40% of eopolymer HB/HV are govemed by the properties of polyamide 6. First at the 50% eopolymer HB/HV eontent in the blend the transitions of the eopolymer HB/HV phase in the blend beeome visible and dominant. The shifts of the lass modulus maxi ms of the blends might indieate same interaetions between the blend eomponents in the amorphous phase. The dynamie meehanieaI storage modlili E' of the blends are almost unaffeeted by the blend eomposition up to the 40 wt. % of eopolymer HB/HV eontent, indicating eontinuous polyarnide 6 matrix in which coJ1olymer HBIHV domains are fixed. The int1uenee,of the eopolymer HB/HV bas been observed first at 50 wt. % eontent, for whieh IWO step drop of the E' value was observed, at temperatures eorresponding to the softening points of erystalline phases of the eomponents. The E' plateau between the softening points may be explained by the existenee of eocontinuous phases of the eomponents. The possibility of interaetions between the blend eomponents in the amorphous phase is eonfirmed by the shifts of the lass modulus maxi ms of the blends (Fig. 34).

• Wydawca: Wydawnictwo Politechniki Gdańskiej
• Czasopismo: Zeszyty Naukowe Politechniki Gdańskiej. Chemia
• Rocznik: 2002
• Tom: nr 49 (592)
• Strony: 3--82
• Opis fizyczny: 34 rys., 26 tab., 159 bibliogr.

Twórcy

autor

Haponiuk J.T.

• Katedra Technologii Polimerów