GAS PERMEATION OF SEGMENTED POLYURETHANES AND THEIR BLENDS WITH PVC

Film specimens of four segmented polyurethanes with different soft segments, namely polycaprolactone, polytetramethylene adipate, polytetramethylene oxide and polypropylene oxide, and their blends with PVC of different compositions were obtained by solution cast. The permeability of these films to O_2, N_2 and H_2 and their density were measured by using gas chromatography and technique of density gradient column. The polyether polyurethanes were found to have higher permeability than the polyester ones due to their low glass transition temperature and /or the low density value. The blends of PVC and polyether polyurethanes, especially the PPO-based polyurethane, are incompatible, and their permeability coefficient-composition dependence has the typical S-shaped curves. PVC is well compatible with the soft segments in its blends with polyester polyurethanes. For these blends the composition dependence of permeability is characterized by a negative deviation from the semilogarithmic additivity rule, and it is possible to prepare blends having T_g 20℃lower than that of PVC, but retaining its low permeability almost unchanged, results were discussed in according with the different approaches for the permeation behavior of compatible and incompatible blends.     

Thermal properties of polyamide 6/polyurethane blends

Equilibrium melting temperatures and crystallization parameters of polyamide 6/polyurethane blends were investigated. Thermal properties of the crystalline phase of blends obtained from polyamide 6 and polyurethane containing 40 wt% of hard segments, are only limited influenced by the overall blend compositon. Because from separate measurements single glass transitions for all samples were estimated, so in the investigated case the blending process may occur mainly between amorphous fraction of polyamide 6 and the polyurethane or, what is more probable, the polyurethane phase is dispersed in the continuous polyamide matrix, although some interactions exist.     

Phase Transitions of Polyamide 6/Polyurethane Blends Compatibilized by Copolyurethaneamides

Blends obtained from polyamide 6 and a thermoplastic polyurethane compatibilized by diblock copolyurethaneamides were investigated by means of DMTA and DSC. The blends were prepared by compounding in a Brabender mixer. The compatibilizer affected the glass transition temperature of the amorphous phase of the blends. The non-isothermal crystallization temperature of the polyamide phase was lowered in the presence of the polyurethane and the copolyurethaneamide. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phase morphology of hydrolysable polyurethanes derived from aqueous dispersions

Biodegradable polyurethanes are an interesting alternative to many applications that involve plastics since they can minimize environmental problems caused by the low rates of natural degradation of synthetic polymers. In addition, since waterborne polyurethanes are based on aqueous dispersions, they restrict the use of organic solvents during processing and application of the polymer, thus contributing furthermore to reduce environmental damage. In this work, aqueous anionic polyurethane dispersions (PUD) with tailorable susceptibility for hydrolysis were synthesized by progressively replacing polypropylene glycol (PPG) with a biodegradable polycaprolactone diol (PCL) as soft segments. The hard segments were formed by extending isophorone diisocyanate (IPDI) with hydrazine (HZ). Dimethylol propionic acid (DMPA) was used as ionic center and triethyl amine (TEA) as neutralizer. The degree of phase separation was evaluated mainly by infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS). The results indicated that phase separation between hard and soft segments of poly(ester-urethane) is more significant than that of poly(ether-urethane). Data obtained from SAXS experiments indicated that phase separation within soft domains can also be present in samples containing both polyester and polyether soft segments. Hydrolytic degradation of the polymers in buffer solution of pH 7.4 and alkaline solution was performed as an initial test. The results showed that the fraction of polyester soft segments in the polyurethanes can be used to tailor the susceptibility of the materials to hydrolytic attack. Polyurethanes having higher contents of polyester were more promptly hydrolytically degraded than polyurethanes containing only polyether segments.     

Influence of copolymer configuration on the phase behavior of ternary blends

The influence of copolymer configuration on the phase behavior of various ternary polymer blends containing a crystallizable polyester, a noncrystallizable polyether, and an acrylic random copolymer of different chain configuration was investigated. In these ternary blends, the acrylic random copolymer is typically added to control rheological properties at elevated temperatures. In fact, the acrylic random copolymers composed of various compositions of MMA and nBMA were found to have different miscibility with polyester as well as polyether, leading to substantially different phase behavior of ternary blends. Remarkable temperature dependence was also found. The mean-field Flory-Huggins theory for the free energy of mixing, extended to ternary polymer blends, was adopted for predicting phase diagrams where the exact spinodal and binodal boundaries could be calculated. Phase diagrams of ternary blends, predicted by the Flory-Huggins formulations and related calculations, were in good agreement with experimental phase diagrams. The differences observed in the rheological processes of various ternary blends with different acrylic copolymers were directly related to changes in miscibility, associated phase behavior, and chain configuration.     

用DSC研究线形多嵌段聚氨酯与聚氯乙烯、氯化聚氯乙烯共混相容性

用示差扫描量热法（DSC）研究了线形多嵌段聚氨酯（PU）与聚氯乙烯（PVC）、氯化聚氯乙烯（CPVC）共混相容性，说明了PU／VC、PU／CPVC的相容是由于共混物中形成了新的氢键的缘故．聚酯型聚氨酯与PVC、CPVC的相容性要好子聚酸型聚氨酯，CPVC与PU的相容性又要好于PVC．聚氨酯中硬段的引入不利于PU／PVC、PU／CPVC的相容性．     

COMPATIBILITY OF PVC WITH POLYURETHANES OF DIFFERENT SOFT SEGMENTS

Blends of PVC and polyurethanes with four different soft segments of molecular weight 1000 were prepared and studied by dynamic mechanical and DSC techniques. It was found that the compatibility of PVC with segmented polyurethanes was related to the mixing of PVC molecules and the soft segments of the polyurethanes. Polyester based polyurethanes are more compatible with PVC than polyether based polyurethanes. Solution cast blends of PVC with PCL-polyurethane (1/2/1) exhibit single and narrow glass transition, while the blends with PPO-polyurethane (1/2/1) are completely incompatible. The compatibility was found to decrease with increasing hard segment content for all the polyurethanes used. The methods of blend preparation may change the compatibility of PVC/PU blends through their influence on the mixing or demixing of the hard and soft segments.     

聚醚聚氨酯-聚醚聚酰亚胺合金相结构的研究

通过不同分子量的对－氨基苯甲酸酯封端的聚（四次亚甲基）醚和均苯甲甲酸二酐反应,合成了聚醚聚酰胺酸;然后以不同重量比将聚醚聚氨酯和聚醚聚酰胺酸溶液混合反应亚胺化,制备了一系列不同硬段含量的聚醚聚氨酯－聚醚聚酰亚胺合金。用傅立叶变换红外光谱、动态力学分析、示差扫描量热、广角Ｘ－衍射、应力应变试验等分析测试方法对合金进行了研究,结果表明聚醚聚氨酯－聚醚聚酰亚胺合金具有很好的相分离结构,是一类新型耐高温、有韧性的热塑性弹性体。聚醚分子量相同的聚氨酯和聚酰亚胺形成的合金软段相容,合金具有两相结构;聚醚分子量不同的聚氨酯和聚酰亚胺形成的合金软段存在相分离,合金具有三相结构,表现在材料外观上分别为透明不透明的韧性膜,少量聚酰亚胺的掺入,能大大增加材料的耐热性能,而合金的材料力学性能没有明显变化。     

Thermal stability enhancement of polyurethanes by surface treatment

Both oxidation and methoxymethylation of the surfaces of a series of MDI (methylene diphenyl isocyanate) and TDI (toluene diisocyanate) polyether and polyester soft segment 1–4 butanediol polyurethanes result in increased thermal stability as measured by TG. Explosive loss of mass above the hard segment melting temperature suggests that the diffusion of the dissociated diisocyanate moiety is hindered at lower temperatures. Thus suppression of the depolycondensation reaction by chemical blockage of the surface may result in a material with an increased service life at use temperatures as thermal stability of a polyurethane may depend upon the low diffusivity of its diisocyanate comonomer. The effect of vacuum, oxygen and water vapor on the kinetics of mass-loss of several of the polyurethanes is presented. In celebration of the 60^th birthday of Dr. Andrew K. Galwey     

SURFACE STRUCTURE AND BULK PROPERTIES OF FLUORINATED POLY(ETHER URETHANE)S AND POLY(ETHER URETHANE) BLENDS

INTRODUCTIONPolyurethanes (PU) have been widely used for manufacturing medical devices because of their excellentmechanical properties and moderate biocompatibility[1]. Although polyurethanes used in applications requiringall of the above properties have been successful for short-term use, the problems of long-term thromboresistanceand biostability in a biological environment still remain unsolved[2,3]. A legitimate approach to improving theproperties of polyurethanes is introduction of f…     

Determination of silicone fluid surfactants in polyurethane/polyether blends by atomic-absorption spectroscopy

A method for the atomic-absorption determination of silicone fluid surfactants present in some polyurethane/polyether blends is described. The silicone fluid in the pure state, or in the presence of polyurethane blend, is diluted with a solvent and sprayed into the nitrous oxide/acetylene flame. The effects of solvent, instrumental conditions, time and presence of the polyurethane blends were investigated. Polyurethane/polyether blends do not interfere with the silicon absorption when the samples are dissolved in aqueous ethanol (1:1) and sprayed into a fuel-rich flame.     

Polymer Compatibilization Through Hydrogen Bonding

Partially modified polystyrene containing vinyl phenyl hexafluorodimethyl carbinol was mixed with a number of counterpolymers containing poly(vinyl-acetate), poly(methyl methacry1 ate), poly(ethy] methacrylate, poly (n-butyl methacry late), poly(viny] methyl ether), poly(2,6 dimethyl-1,4 phenylene oxide), bisphenol A polycarbonate poly(styrene-co-acryloni-trile), poly (dimethyl siloxane), a crystallizable polyester, an amorphous polyamide and two amorphous polyamides. Hydrogen bonding interactions to effect miscibility were related to the number of proton donating groups in the modified polystyrene, and these were studied in regard to lower critical solution temperatures and the glass transition temperatures of the hydrogen bonded blends.     

Design,polymerization, and properties of polyurethane elastomers from miscible,immiscible, and hybridized seed‐oil derived soft segment blends

Polyester seed‐oil derived polyols have been prepared and blended with conventional polyols for making polyurethane elastomers. Miscibility was complete for polypropylene oxide/polyethylene oxide and polytetramethylene oxide (PTMEG). Blends of polyester seed‐oil derived polyols with conventional polyester polyols (polybutylene adipate and ?‐polycaprolactone) were immiscible or nearly so. Furthermore, the phase behavior (miscible vs. immiscible) did not change appreciably for each blend composition explored as a function of temperature at relevant ranges (up to the polyether ceiling temperature). This counter‐intuitive result is found to be actually consistent with calculated solubility parameters for each polyol type and the phase diagrams computed on their basis. The phase behavior of the polyols is shown to have significant effects on the properties of polyurethane elastomers where immiscible polyols cause broadening of the glass transition distribution and significant reduction of ultimate tensile properties. However, here it is shown that immiscible systems containing polyester seed‐oil derived polyols can be transesterified with the appropriate polyol partner of interest to create a new single phase polyol or that the polyester polyol monomers can also be copolymerized to make new single phase polyols, both of which result in improved polyurethane elastomer properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 93–102     

氟化聚氨酯的合成和表征

综述了各种不同结构的氟化聚醚《型和氟化聚酯型聚氨酯的合成并对产物的化学性能进行了描述。对各种表征方法的结果讨论表明,由于结构的特殊性,氟化聚氨酯有其不同于非氟化聚氨酯的特性。     

SAXS analysis of a linear polyester and a linear polyether urethane—interfacial thickness determination

A small-angle x-ray scattering (SAXS) investigation of two linear segmented polyurethanes was carried out to learn about the respective domain structure (morphology). Both urethanes had a hard segment of methylene-bis(4)phenyl isocyanate (MDI) and butanediol. These two components comprised 28% by weight of each system. The soft segments differed in that one was a polyether (tetramethylene oxide, molecular weight 1000), while the other was a polyester (polytetramethylene adipate, molecular weight 1000). Both of these segmented urethanes were stored at room temperature for over 6 months prior to investigation. Using an automated Kratky camera, SAXS scans were made. By detailed analysis (using the computer program of Vonk) the average interfacial thickness E of the domains was determined by two approaches. The value of E for the polyester was 10–12 Å, while it was 5–7 Å for the polyether. Within the limits of the assumptions used for analysis, these data directly support the conjecture that polyether urethanes generally lead to better phase separation. Other aspects of the analysis provided further information on the morphological structure. Some cautionary comments are provided on the use of quantitative SAXS data obtained from these or similar systems.     

Catalytic thermal decomposition of polyamides and polyurethanes mixed with acidic zeolites

The purpose of this work was to examine the pyrolysis products derived from zeolite–polyamide and zeolite–polyurethane mixtures prepared in different ratios in order to elucidate the chemical reactions taking place under pyrolysis of these polymers in the presence of acidic Y zeolites (ultra stabilized HY (HUSY) and NH₄NaY). Therefore 5:1, 3:1, and 1:1 ratios of zeolite and nitrogen-containing polymer (polyamides and polyurethanes) mixtures were pyrolysed at 500 °C in a micro-pyrolyser on-line coupled with GC/MS. The products and product distribution of zeolite–polymer mixtures indicate that the amount of catalysts significantly affects the pyrolysis product distribution. In case of zeolite–PA-6,6 1:1 mixtures hexanedinitrile is the main pyrolysis product indicating that the thermal decomposition of PA-6,6 via cis-elimination is enhanced. Main pyrolysis products of zeolite–PA-6 mixtures of 1:1 ratio are dihydro-azepine isomers that are the dehydrated derivatives of ɛ-caprolactam. Pyrolysis of 1:1 zeolite–PA-12 mixtures leads to the promoted formation of dehydrated cyclic monomer isomers (azacyclotrideca-dienes). For zeolite–PUR 1:1 mixtures it was concluded that MDI decomposition to N-containing aromatics is enhanced, while the polyester and polyether segments degrade to monomer type products and to aromatics. For all zeolite–polymer mixtures increasing ratio of catalysts leads to increased amount of aromatics (benzene and naphthalene compounds) and light unsaturated hydrocarbons, while the amount of main products of 1:1 mixtures decreases.     

Dynamic Mechanical Thermal Analysis of Polyamide 6/Biopol Blends

The temperature dependence investigated by means of DMTA of dynamic storage modulusE′, dynamic loss modulus E″ and loss tangent tgδ of blends obtained from polyamide 6 and poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (Biopol D600G) indicated, that the dynamic mechanical properties of the blends containing up to 40% Biopol D600G are governed by the properties of polyamide 6. First at the 50% Biopol D600G content in the blend the transitions of the Biopol phase become visible and dominant. The shifts of the loss modulus maxima of the blends might indicate some interactions between the blend components in the amorphous phase. This revised version was published online in August 2006 with corrections to the Cover Date.     

Studies on the relationship of structure and properties of the polyesterurethanes adhesives

Three series of linear segment polyurethanes (PHAU, PBAU, PEAU) based on three polyesters (PHA, PBA, PEA), MDI and butanediol were synthesized by solution polymerization. The crystallinity of these polyesters and polyurethanes and the compatibility of Blends of polyurethane (PU) with poly(vinyl chloride) (PVC) were studied by means of X-ray diffraction, DSC, DMA and phase contrast microscopy respectively. The influence of polyester type and molecular weight, the hard-segment content in PU on the crystallinity of PU and the influence of compatibility on adhesion are discussed. The results showed that, on condition that the hard-segment content was not high (< 25%), the crystallinity in PU was mainly caused by the polyester, soft-segment, which was in the order of PHA PBA PEA, and that, PBAU/PVC, PHAU/PVC were compatible systems, but PEAU/PVC was incompatible. The adhesive strength of the three adhesives was quite different from one another, with the order of PBAU PHAU PEAU. An interpretation of adhesion for the PU-PVC system by the diffusion theory is proposed.     

Hydrolytic stability of nano-particle polyurethane dispersions: Implications to their long-term use

Nano-particle segmented polyurethane anionomer dispersions with ions either on the soft segment or on the hard segment were synthesised using 2,2-bis(hydroxymethyl) propionic acid and 5-sodiosulfo-1,3-benzenedicarboxylic acid as ionic centre. The resulting polyurethane dispersions were characterized for their particle size, reduced viscosity and hydrolytic stability in the presence of the aqueous phase during storage. At similar ionic contents, the polyurethanes that contain ionic groups on their soft segment had smaller particle sizes than those that contain ionic groups on the hard segment due to the effectiveness of the sulphonate ionic groups incorporated in the former. The reduced viscosity of the anionomers in dimethylformamide (DMF) showed typical polyelectrolyte effect that can be eliminated by the addition of LiBr. The hydrolysis study conducted over 2-years indicated that polyurethanes in which the ions were located on the hard segment had better hydrolytic stability in aqueous environment than those with ions located on the soft segment. We attributed this due to the fact that unsolvated hydrophobic polyester segments were packed in the interior of the particles while the strongly hydrated urethane segments with mutually repelling carboxylate ions were situated on the outside surface of the particles. The polyester groups prone to hydrolytic attack were thus protected against hydrolysis as effectively as in the dry solid form.     

Morphology of polyurethanes with triol monomer crosslinked on hard segments

Polyester‐based polyurethanes containing ≈60 wt % of polyester were synthesized from low molecular weight polyester (M_n ≈2000) and 4,4′‐methylene bis(phenyl isocyanate) (MDI), with butanediol as a chain extender and glycerol as a crosslinker. The triol crosslinker was used in substitution for the 1,4‐butanediol chain extender; thus, the crosslinker was chemical bonded to the hard segments of polyurethane. The morphologies of these polyurethanes were studied by differential scanning calorimetry (DSC), small‐angle X‐ray scattering (SAXS), TMA (thermal mechanical analysis), and FTIR (Fourier transform infrared spectroscopy). Owing to the highly steric hindrance, the presence of triol crosslinker in the hard segments resulted in a decrease in the aggregation of hard segments through hydrogen bonding. The experimental results revealed that the degree of phase segregation of soft and hard segments decreased with increasing the triol crosslinker content in the hard segments. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2673–2681, 1999