Melt spinnable spandex fibers from segmented copolyetheresteraramids

Spandex fibers were obtained by melt spinning segmented copolyetheresteramides with crystallizable aromatic diamide units of uniform length and poly(tetramethyleneoxide) segments. The aramid content was varied from 3 to 22 wt %, and the molecular weight of the polyether segment ranged from 1000 to 9000 g/mol. The influence of the spinning and drawing conditions on the fiber properties was investigated. The aromatic diamide units crystallize very fast. This made the melt spinning of the polymers easy. The aramide units were also found to be very effective in increasing the modulus. For a high elasticity a low aramid content was beneficial, and with a few percent a good elastic behavior is obtained. Orientation by drawing or a spin drawing process improves the elastic behavior. The elastic properties are compared to the values of commercial spandex fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2194–2203, 2001     

Comparison of properties of segmented copolyetheresteramides containing uniform aramid segments with commercial segmented copolymers

The thermal (using differential scanning calorimetry), dynamic mechanical (using a dynamic mechanical analyzer), and mechanical properties of segmented copolyetheresteramides with aramid units of uniform length (TΦT) and poly(tetramethylene oxide) (PTMO) segments were compared to those of commercial segmented copolyetheresters (PBT–PTMO) and thermoplastic polyurethanes. The hard segments in TΦT‐containing polymers were found to crystallize almost completely, unlike the hard segments of Arnitel and Desmopan. Consequently, the glass‐transition temperature of TΦT‐containing polymers is lower and the melting temperature higher than those of Arnitel and Desmopan. Furthermore, the rubbery plateau of the TΦT‐containing polymers is temperature independent, making the service temperature range wider. In TΦT‐containing polymers a lower concentration of hard segment is needed to obtain dimensionally stable polymers with a high melting temperature. No melt phasing occurs during polymerization and therefore long PTMO segments can be used, producing very soft and elastic materials. The polymers crystallize faster than do commercial materials. The elasticity of the TΦT‐containing polymers is comparable to the elasticity of Desmopan and better than that of Arnitel. TΦT–(PTMO₁₀₀₀/DMT) copolymers are transparent and the solvent resistance is high. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1372–1381, 2001     

Effect of diisocyanates and chain extenders on the physicochemical properties and morphology of multicomponent segmented polyurethanes based on poly(l‐lactide), poly(ethylene glycol) and poly(trimethylene carbonate)

Multicomponent segmented polyurethanes (SPUs) based on poly(ethylene glycol), poly(l ‐lactide) and poly(trimethylene carbonate) as macrodiols, 2,4‐toluene diisocyanate (2,4‐TDI) or 1,6‐hexane diisocyanate (HDI) as diisocyanate, and 1,4‐butanediol (BDO) or 2,2‐bis(hydroxymethyl)propionic acid (DMPA) as chain extenders were synthesized. The molecular, thermal, dynamic mechanical and morphological features of this set of uncrosslinked polyurethanes are characterized using ¹H NMR, gel permeation chromatography, differential scanning calorimetry, dynamic mechanical thermal analysis (DMTA) and atomic force microscopy techniques. The lower reaction rate of HDI in comparison with 2,4‐TDI allows for better control of the SPU compositions, so that the intrinsic properties of each block can be better combined and modulated. HDI‐based SPUs are semi‐crystalline, while those based on 2,4‐TDI are amorphous, affecting the mechanical properties of these polyurethanes. All SPUs are heterogeneous, presenting morphologies of a disperse phase in a matrix which varies with the macrodiol ratios as well as with the nature of the diisocyanate and chain extender (a finer dispersion of the disperse phase is observed for SPUs of HDI and BDO). DMTA results indicate that the phases are complex mixtures of the different blocks with at least one rich in PLLA. The PEG content is shown to be the most important factor influencing the water sorption capability, while the incorporation of hindering carboxylic acid groups by the use of DMPA allows the water uptake of SPUs to be controlled by the solution pH. All SPUs show a significant loss of molar mass in hydrolytic degradation experiments and, in general, the PLLA‐rich SPUs are more susceptible to degradation. © 2015 Society of Chemical Industry     

Synthesis and characterization of segmented polyurethanes containing aromatic diol chain extenders

A series of segmented polyurethanes (SPUs), based on hexamethylene diisocyanate (HDI) and polytetramethylene glycol (PTMG) as soft segments and then extended with alkylene di(4-hydroxybenzoate), HB as hard segments, were synthesized in this study. The effect of the number of methylene units in HB (from 2 to 6) on the microphase separation of the SPUs was evaluated by means of a differential scanning calorimeter (DSC) and a polarized optical microscope (POM). The kinetic reaction between HB and HDI was determined by Fourier transform infrared spectroscopy. The rate constants of the second-order kinetics showed that the reactions of HDI and HB with odd numbers of methylene units appeared to be faster than those with even numbers of methylene units. The results from POM showed that the SPUs with even numbers of methylene units in the HB have a higher degree of phase separation between the hard and soft segments than those with odd numbers of methylene units in HB. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 539–546, 1997     

Structure-property behaviour of segmented polyether-MDI-butanediol based urethanes: effect of composition ratio

The structure-property relationship of a systematic series of segmented polyurethanes was investigated segment was 4,4′-diphenylmethane diisocyanate (MDI) extended with 1,4-butanediol, and the soft segment was 2000 M_w poly (tetramethylene oxide) ether. X-ray studies reveal that some hard segment segment was 2000 mW poly (tetramethylene oxide) ether. X-ray studies reveal that some hard segment crystallization occurs at high hard segment content (45%). In addition, other morphological changes take place as the hard segment fraction is increased. The texture changes from that in which little such domain content exists at low hard segment levels (15%), to that in which the polymer has an interlocking domain morphology at high hard segment content (35 and 45%). Preferable elastomeric properties (low hysteresis, high extension) can be obtained when isolated hard segment domains exist (25% hard segment). Thermal treatment of the samples results in domain disruption and hard-soft segment mixing. However, this phenomenon, and the consequent time-dependent structure recovery as the material is allowed to age, is composition dependent. In general, crystalline domains, when present, are disrupted the least while the fastest recovery is displayed by samples with noncrystalline domain texture. This behaviour can be explained qualitatively in terms of kinetic diffusion effects relative to the thermodynamic driving forces for phase separation.     

Polyether‐amide segmented copolymers based on ethylene terephthalamide units of uniform length

Segmented copolymers were synthesized using the crystallizable bisesterdiamide segment (N,N′‐bis(p‐carbomethoxybenzoyl)ethanediamine) T2T‐dimethyl (a one‐and‐a‐half repeating unit of nylon 2,T) and poly(tetramethyleneoxide) segments. Poly(tetramethyleneoxide) (PTMO) is amorphous and has a low T_g. The segment length was varied from 650 to 2800 g/mol by extending PTMO₆₅₀ using dimethyl isophthalate. The polymers were synthesized in the melt, and test samples were prepared by injection molding. The melting behavior, as well as the torsion modulus spectrum as a function of temperature, were studied using DSC and DMA, respectively. The T2T‐PTMO polymers were found to have sharp glass (T_g) and flow transitions (T_fl), and the modulus at the rubbery plateau appeared to be virtually temperature independent. The T_g value was found to be independent of the diamide concentration, thus indicating that the T2T segments were fully crystallized. The T_fl was found to decrease with increasing soft segment length; this was ascribed to a “solvent” effect of the amorphous phase of the crystalline T2T units. The difference between the melting and crystallization temperatures was found to be low, thus suggesting that on cooling, there is a high rate of crystallization. When ethanediol was added as a T2T segment extender, amide‐ester‐amide segments were introduced. These amide‐ester‐amide segments form a separate lamellar phase with a much higher melting temperature (>300°C). It was found that the crystallization rate of the T2T units was enhanced by the presence of the amide‐ester‐amide segments, indicating that upon cooling, the crystallized amide‐ester‐amide segments form the nucleation sites for the nonextended T2T segments. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1173–1180, 2001     

Synthesis and characterization of rubbery highly fluorinated siloxane–imide segmented copolymers

The synthesis and characterization of a series of poly(siloxane–imide) block (or segmented) copolymers obtained by copolymerization of amine‐terminated polydimethylsiloxane with fluorinated aromatic compounds containing anhydride and amine functionality are reported. New fluorinated block copolymers have been synthesized to obtain organophilic polyimides potentially interesting for molecular membrane separations. The new aspects of this work relative to the literature are (1) a comparison of solution and solid‐state approaches in the imidization step to generate the target poly(siloxane–imide) copolymers and (2) exploration of new compositions involving fluorinated aromatic polymers derived from added diamine compounds. It is shown that the copolymer properties can be tailored from glassy to rubbery materials by varying the amount and the type of oligosiloxane used; the transition between glassy and rubbery properties is characterized at a siloxane content of 60 wt%. As a main result, it is shown that the solid‐state approach for inducing the cyclo‐imidization step is the more efficient one for synthesizing polymers with good mechanical properties, when the amount of siloxane block is increased in the copolymer series. Physical and chemical methods (thermogravimetric analysis, Fourier transform infrared spectroscopy, viscosity measurements) were used to characterize the copolymer properties obtained according to the two different synthesis routes. The obtained siloxane–imide copolymers are well soluble in a large variety of moderately polar solvents and exhibit very good thermal stability up to 400 °C. Hence the prepared copolyimides would seem to be promising candidates as organophilic membranes as well as gas permeation membranes. © 2012 Society of Chemical Industry     

Synthesis and properties of segmented polyurethane using phenolphthalein as chain extenders

Three series of novel polyurethane elastomers containing phenolphthalein as chain extenders were synthesized. The structure of the polyurethane was analyzed using IR and wide-angle X-ray diffraction studies. Tensile strength and percentage of elongation of all the series of polymers were studied. Thermal decomposition was studied using differential scanning calorimetry. © 1993 John Wiley & Sons, Inc.     

Microphase separation and surface properties of segmented polyurethane-Effect of hard segment content

A series of segmented polyurethanes (SPU), based on 4,4′-diphenylmethane diisocyanate and 1,4-butanediol as hard segments (HS) and poly(propylene glycol) (Mn = 1000) as soft segments, were synthesized. Relationships between microphase separation and the surface and adhesive properties were characterized by thermal analysis, X-ray diffraction, contact angle, electron spectroscopy for chemical analysis, T-peel and tensile test measurements. Microphase separation occurred for SPU with an HS content of more than 50 wt% and influenced not only the bulk properties, but also the surface properties. Young's modulus and tensile strength increased abruptly for SPU with an HS content of more than 50wt%. Surface free energy also increased in a stepwise manner at an HS content of about 50wt%. The optimum HS content of SPUs for adhesion, based on T-peel test results, also gave good thermal and mechanical properties.     

Factors influencing thermal,mechanical, optical,and adhesive properties of segmented poly(imide siloxane) copolymers films

Poly(imide siloxane), block and blend copolymer, were synthesized using different methods to explore the influence of siloxane chains. The flexible siloxane chains enrichment on surface of copolymer, enhance hydrophobic and adhesive with copper foil. It also improves light transmittance of polyimide film in the visible light region. The effect of different preparation methods on the aggregation in polymers and on polymer properties, especially adhesion and water absorptivity, are also discussed. The imidization temperature and synthesis method (blend and block) during the reaction has a significant effect on the properties of the product, especially thermal properties (T _g values are 207 °C for block and 180 °C for blend) and mechanical properties (elongation of 130% for block and 50% for blend). The bonding strength of polymer films used as hot melt adhesive was also tested. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48148.     

Thermal and mechanical properties of solution polymerized segmented polyurethanes with butadiene soft segments

A series of HTPBD containing polyurethanes of high molecular weight have been synthesized in solution. The value of the soft segment T_g is very close to that of the free HTPBD and independent of hard segment content indicating complete or very nearly complete phase segregation. Since the hard segments of TDI/BDO are amorphous, the driving force for phase segregation must arise from the large degree of incompatibility between the polar hard segment and nonpolar soft segment. Furthermore, in these samples there is also no opportunity for hydrogen bonding between hard and soft segments to enhance compatibility.The values of the hard segment glass transition increase with the average hard segment length following a Fox-Flory type relationship. In contrast to the segment T_g observed in bulk polymerized samples, only a single hard segment T_g occurred in the present study. This indicates that the double T_g behaviour is a result of the heterogeneous nature of the bulk polymerization.With increasing hard segment content, the properties vary from soft to rigid elastomers, and rubber roughened plastics. This variation in properties is caused by changes in the sample morphology which depends upon the relative fractions of hard and soft segments. Mechanical properties show marked improvement over the corresponding bulk polymerized samples. Unlike polyester and polyether urethanes, these materials evidence no change in the soft segment T_g following thermal treatment and no effect of thermal history on the mechanical properties.     

Studies on thermally stimulated shape memory effect of segmented polyurethanes

The shape memory behavior of a series of polycaprolactone/methane diisocyanate/butanediol (PCL/MDI/BDO) segmented polyurethanes of different composition was studied. The molecular weight of PCL diols was in the range of 1600–7000, and the hard segment content varied from 7.8 to 27% by weight. Film specimens for shape memory measurements were prepared by drawing at temperatures above the melting temperature of the soft segment crystals and subsequent quick cooling to room temperature under constrained conditions. The shape memory process was observed and recorded in a heating process. Parameters describing the recovery temperature, ability, and speed were used to study the influence of structure and processing conditions on the shape memory behavior of the sample. It was found that the high crystallinity of the soft segment regions at room temperature and the formation of stable hard segment domains acting as physical crosslinks in the temperature range above the melting temperature of the soft segment crystals are the two necessary conditions for a segmented copolymer with shape memory behavior. The response temperature of shape memory is dependent on the melting temperature of the soft segment crystals. The final recovery rate and the recovery speed are mainly related to the stability of the hard segment domains under stretching and are dependent on the hard segment content of the copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1511–1516, 1997     

Synthesis and selected properties of polyurethanes with monodisperse hard segments based on hexane diisocyanate and three types of chain extenders

Poly(ethylene glycol) grafted octadecyl quaternized carboxymethyl chitosan (PEG-g-OQC) copolymers were synthesized to both improve the biocompatibility of OQC and form PEGylated cationic polymeric liposomes (CPLs), which composed of the mixture of OQC, cholesterol, and PEG-g-OQC. Structure of the copolymers was characterized by using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹H-NMR), and X-ray diffraction (XRD). The methyl tetrazolium (MTT) assay with L929 cell lines confirmed that PEGylation can decrease the cytotoxicity of OQC. PEGylated CPL nanoparticles (NPs) can be prepared by adding different weight ratio of PEG-g-OQC in the mixture. Paclitaxel was successfully incorporated into PEGylated CPLs with high drug encapsulating efficiency (>90%) and drug loading capacity (>15%). Physical stability experiment showed that paclitaxel-loaded PEGylated CPLs was stable with little change of particle size and size distribution in the condition of freeze-dried by adding mannitol or in high temperature and high pressure. Power or reagent of drug-loaded PEGylated CPLs showed a slow steady release profile for paclitaxel. These results show that PEG-g-OQC and CPLs have potential application as a drug delivery vehicle. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of chemical crosslinks on the elastic behavior of segmented block copolymers

Polyether(ester-amide)s (PEEA) segmented block copolymers with di- and tri-functional poly(propylene oxide)s and amide segments were synthesized and the elastic properties studied. The difunctional polyether used had a molecular weight of 2300 g/mol end capped with 20 wt% ethylene oxide. The trifunctional polyether had a molecular weight of 6000 g/mol of which each arm had a molecular weight of 2000 g/mol. The concentration of the trifunctional polyether of the total ether content was varied from 0 to 40 mol%. The amide segments were of a non-crystallizing type with a content in the copolymers of 27 wt%. Phase separation occurred, therefore, only by liquid-liquid demixing. The thermal mechanical properties of the polymers were analyzed by dynamic mechanical thermal analysis and the elastic properties by compression set and tensile set. The materials are model blockcopolymers for the more complex chemically crosslinked polyether(urethane-urea)s (PEUU).With increasing amounts of chemical crosslinks the glass transition temperature and the modulus did not change noticeably. However, the elastic behavior as measured by compression set and tensile set, improved dramatically. Giving time all materials recovered completely and with increasing amount of chemical crosslinks this recovery happened faster. An explanation is given for the (viscoelastic) deformation in these copolymers.     

Influence of chain extenders on the melt strength and thermal stability of polyglycolic acid

Biodegradable polyglycolic acid (PGA) has been attracting much attention recently. However, poor melt strength and thermal stability limit the processing of PGA by methods such as film blowing and injection molding. To improve melt strength and thermal stability, two reactive chain extenders, styrene–acrylonitrile-glycidyl methacrylate terpolymer (poly(St-AN-GMA)) and 4, 4′-methylenebis(phenyl isocyanate) (MDI), were incorporated respectively into PGA using twin-screw extrusion. MDI was found to be more effective in chain extension and enhancing thermal stability than poly(St-AN-GMA). The T_-5% (the temperature where the remaining weight percentage is 95%) of PGA modified with 3 wt% MDI increased to 334.5°C from 310.8°C for pure PGA. Melt flow rate for the same materials decreased from 47.2 g/10 min to 13 g/10 min. The activation energy of thermal degradations for MDI-modified PGA was twice that of the unmodified PGA as evaluated by the Flynn-Wall-Ozawa method.     

扩链剂在阻燃高回弹聚氨酯泡沫中的应用

分别采用三乙醇胺(TEOA)、二乙醇胺(DEOA)和甘油(GLY)三种扩链剂制备阻燃高回弹聚氨酯(FRHRPU)泡沫塑料.探讨了TEOA,DEOA,GLY对FRHRPU泡沫塑料反应活性、泡孔结构及制品力学性能的影响.结果表明:以DEOA为扩链剂制备的FRHRPU泡孔孔径为200.00 μm、氧指数为28.7％,工艺稳定性及力学性能优于其他两种扩链剂制备的FRHRPU.DEOA可广泛应用于FRHRPU泡沫塑料.     

嵌段聚醚酯弹性纤维的老化及热分解

通过测定以PBT为硬段 ,聚乙二醇 (PEG)和聚丁二醇 (PTMG)为软段的嵌段聚醚酯弹性纤维在老化前后的特性粘数、断裂强度、断裂伸长率和弹性回复率的变化 ,发现添加抗氧剂能明显改善该弹性纤维的抗老化性能并提高纤维的力学性能和回弹性能 ;采用热失重测定了PBT -PTMG2嵌段聚醚酯弹性纤维的热分解性能 ,热分解动力学计算表明其热分解活化能较低 ,为 69.6kJ ,容易热分解 ,热分解为 1级反应     

Influence of morphology on the properties of segmented block copolymers

A comparison was carried out regarding the structure and properties of segmented block copolymers with either non-crystallisable or crystallisable rigid segments. The flexible segment in the block copolymers was a linear poly(propylene oxide) end capped with poly(ethylene oxide), with a segment molecular weight of 2300 g/mol. The rigid segments were either non-crystallisable or monodisperse crystallisable polyamides of varying lengths. The morphologies were studied by TEM and AFM, the thermal mechanical properties by DMA and the elastic properties by compression set and tensile measurements. A direct comparison was made of segmented block copolymers with either liquid-liquid demixed or crystallised structures. The crystallised amide segments were more efficient in increasing the modulus and improving the elastic properties than the non-crystallisable ones. The copolymers with crystallised structures were transparent, had a low glass transition temperature of the polyether phase and a modulus that was independent of temperature between T_g and T_m. These copolymers also displayed a very low loss factor (tan δ), suggesting excellent dynamic properties. The hard phase in segmented block copolymers should thus preferably be crystalline.     

The action of chain extenders in nylon-6, PET,and model compounds

The action of two complementary chain extenders is studied in model systems as well as in poly(ethylene terephthalate) (PET) and nylon–6. Chain extenders are low molecular weight compounds that can be used to increase the molecular weight of polymers in a short time. The reaction must preferably be fast enough to execute this step in an extruder. 1,3-Phenylene bis(2-oxazoline-2) (PBO) and isophthaloyl biscaprolactamate (IBC) are used in this study. Bisoxazolines react quickly with carboxylic acids. With model compounds it is shown that, under processing conditions, high conversions can be reached. However, the conversion is not complete. The high rate and the absence of volatile reactants are the most important characteristics of this reaction. Bislactamates are suitable coupling agents for hydroxy and amino functional polymers. The path of this coupling reaction depends on the type of nucleophile and on the reaction temperature. Under mild conditions the elimination of caprolactam is the main reaction. Under more severe conditions the ring opening mechanism may also be operative. The increase of the viscosity is studied with one as well as with a mixture of the two chain extenders. The effect is larger when both types of chain extenders are used simultaneously. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1813–1819, 1997     

Segmented organosiloxane copolymers: 2 Thermal and mechanical properties of siloxane—urea copolymers

The structure-property behaviour of new siloxane-urea containing segmented copolymers has been investigated. Amino-propyl terminated poly(dimethylsiloxane) oligomers of from 900–3660 M_n were reacted with various diisocynates to form segmented copolymers with urea linkages. The length of the hard segments in these copolymers corresponds approximately to the length of the diisocynate unit employed. A number of mechanical and thermal properties were investigated for these phase separated materials. It was found that the performance of these copolymers was effected by varying the hard segment type and/or content and that high strength necessitates a microphase texture. The two phase nature of these copolymers was verified by dynamic mechanical, thermal and SAXS studies. The phase separation was found to occur in these copolymers even with 6% hard segment by weight. In conclusion, these materials displayed a behaviour similar to the segmented polyurethanes and were found to be superior to the unfilled silicone elastomers.