聚己内酯二醇型水性聚氨酯分散液的合成和性能

聚己内酯二醇(PCL)是由己内酯开环聚合而成的性能优良独特的聚酯,由于结构的独特性,它可作为原料用于合成高性能的聚氨酯弹性体、胶粘剂、涂料等。本工作以Solvay公司CAPA系列的PCL为基础原料,合成了水性聚氨酯分散液,研究了其相应的胶体性能、力学性能以及热力学性能。研究发现,虽然引发剂在PCL中只占3.0％-4.5％,却对聚氨酯性能的影响较大,PCL的相对分子质量、软硬段比及扩链剂种类等对水性聚氨酯的性能也有影响。     

高固含量双组分混合聚酯型水性聚氨酯的合成

以异佛尔酮二异氰酸酯(IPDI)为硬段、混合双组分聚酯二元醇和1,4-丁二醇(BDO)为软段、二羟甲基丙酸(DMPA)为亲水扩链剂、三乙胺(TEA)为中和剂和乙二胺(EDA)为后扩链剂等,采用预聚体分散法合成了系列高固含量的水性聚氨酯(WPU)乳液。以固含量、黏度和吸水率等为衡量指标,比较了不同聚酯二元醇的混合效果。结果表明:当混合聚酯中n(PBA或PCDL)∶n(PEBA或PCDL)=1∶1、w(DMPA)≈3.4%(相对于预聚体而言)、n(-NCO)∶n(-OH)=1.03∶1和中和度为96%时,由PBA2000/PCDL2000混合聚酯二元醇制取的WPU乳液,其固含量较高(48.70%)、黏度最低(542 mPa.s)且综合性能相对较好。     

不同结构水性聚氨酯分散体的合成与性能研究

用不同结构不同分子质量的聚酯多元醇合成一系列水性聚氨酯分散体,探讨了其力学性能、黏度、粘附力和贮存稳定性,还分析了结晶性、扩链剂和硬段含量对水性聚氨酯性能的影响.结果表明,用PBA和PHA合成的水性聚氨酯具有较好的性能,适度的结晶性有利于提高粘附力,扩链交联剂在一定的比例范围才能保持分散液的稳定性,40%～46%硬段含量可以保证水性聚氨酯既有较好的力学性能和黏度,又有满足使用要求的干燥速度.     

Structure and mechanical properties of thermoplastic polyurethane,based on hyperbranched polyesters

A series of hyperbranched polyurethane (HB‐PU) were synthesized using hyperbranched polyester as a precursor. Morphology of these HB‐PU films was investigated using atomic force microscopy and wide‐angle X‐ray diffraction; it's molecular dynamics was studied by dynamic mechanical analysis. FTIR studies showed that hard segments get more aggregated to form domains in the HB‐PU block copolymer as hard segment content increases. Such domain formation has a significant influence on the mechanical and thermomechanical properties of HB‐PU, such as maximum stress and elongation at break. Especially, maximum stress and elongation at break increased significantly at 25 wt % of hard segment content, and the highest loss tangent was observed at the same composition. Heat of crystallization as measured by differential scanning calorimetry is also dependent on the hard segment content, and the control of hard segment content in PU block copolymers is very important in determining their physical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5266–5273, 2006     

Comparison of properties of thermoplastic polyurethane elastomers with two different soft segments

Two series of thermoplastic polyurethane elastomers [poly(propylene glycol) (PPG) based PP samples and poly(oxytetramethylene)glycol (PTMG) based PT samples] were synthesized from isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/PPG and IPDI/BD/PTMG. The IPDI/BD based hard segments contents of polyurethane prepared in this study were 40–73 wt %. These polyurethane elastomers had a constant soft segment molecular weight (average M_n, 2000) but a variable hard segment block length (n, 3.5–17.5; average M_n, 1318–5544). Studies were made on the effects of the hard segment content on the dynamic mechanical thermal properties and elastic behaviors of polyurethane elastomers. These properties of PPG based PP and PTMG based PT samples were compared. As the hard segment contents of PP and PT samples increased, dynamic tensile modulus and α-type glass transition temperature (T_g) increased; however, the β-type T_g decreased. The permanent set (%) increased with increasing hard segment content and successive maximum elongation. The permanent set of the PT sample was lower than that of the PP sample at the same hard segment content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1349–1355, 1998     

Composition and processing effects on the properties of one-component polyurethanes

A polyurethane consisting of a poly(propylene oxide) soft segment and a diphenylmethane diisocyanate—hydroquinone di-(b?-hydroxyethyl) ether (HQEE) hard block has been characterized over the composition range of 30 to 60 percent hard block. The flexural modulus varied from 60 to 900 MPa over this composition range. The elongation was approximately 250 percent at the lower hard block contents but fell below 100 percent at 60 percent hard block. Differential scanning calorirnetric measurements showed that the crystallinity associated with the hard phase increased with increasing hard block content but decreased with increasing cure temperature. The heat sag was found to decrease with increasing hardblock and increase with increasing cure temperature. A material with properties comparable to current fascia materials had a significantly better heat sag resistance than a current RIM (reaction injection molding) polyurethane. The combination of the solid chain extender, HQEE, and a solid catalyst, zinc stearate, lowing it to be processed as a one-component resin having a pot life of greater than 8 h at 20°C al-injection molding machines. The one-component nature of the resin has made it possible to use a continuous in-line mexer and to reduce the amount of scrap by using cold runner molds. In addition, any scrap that is generated can be used as regrind in the system.     

Properties of Waterborne Polyurethane Adhesives: Effect of Chain Extender and Polyol Content

A series of waterborne polyurethane (WBPU) adhesives were prepared with various ratios of polyol, poly(tetramethylene oxide glycol) (PTMG), and chain extender, ethylene diamine (EDA), at a fixed content of diisocyanate, 4,4-dicyclohexylmethane diisocyanate (H₁₂MDI) and hydrophilic agent, 2,2-dimethylol propionic acid (DMPA). WBPU adhesives were characterized by IR and ¹H-NMR spectroscopies, X-ray diffraction (XRD) and gel permeation chromatography (GPC). It was found that the extent of hydrogen bonds between hard–hard segment (i.e., hydrogen bonds between the NH and carbonyl groups) increased with increasing chain extender content (decreasing polyol content). Moreover, the disordered hydrogen bond of carbonyl group (hydrogen bond of urethane groups in the interfacial region) increased with increasing chain extender content (decreasing polyol content). The cyclic urea and allophanate group, which are attributed to the side reaction and cross-linking reaction, respectively, were found above a molar ratio 0.17 of chain extender to diisocyanate. The adhesive strength was maximum with 0.95 wt% and 63.10 wt% chain extender and soft segment (PTMG), respectively (H2 sample) at room temperature for the WBPU adhesive. However, with increasing application temperature the adhesive strength decreased for all samples.     

Vibration control ability of multilayered composite material made of epoxy beam and polyurethane copolymer with shape memory effect

Sandwich‐type layered composite material was prepared with epoxy beam and polyurethane copolymer that was synthesized from 4,4‐methylene bis (phenylisocyanate), poly(tetramethyleneglycol), and 1,4‐butanediol as a chain extender. As for the polyurethane, shape recovery was improved with higher content of hard segment, and the highest damping effect as judged by tan δ was observed at 30–35% hard segment. The composite material had better impact strength and higher tan δ than epoxy beam alone, but the superiority became less as more hard segment was incorporated. The interfacial binding force between polyurethane and the epoxy beam also decreased in proportion to the hard segment content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 302–307, 2004     

Studies on impact modification and fractography of solution cast blends of PVC and NR/PU block copolymers

Segmented polyurethanes based on toluene diisocyanate (TDI) with three different chain extender diols, viz., propylene glycol (PG), 1,4-butanediol (1,4-BDO), and 1,3-butanediol (1,3-BDO) were synthesized by a two-step, solution polymerization method. These different NR-b-PU block copolymers were incorporated into PVC at various compositions by the solution blending method. These blend systems were subjected to FTIR analysis, DSC, tensile testing, tensile impact measurements, and tensile impact fracture studies by SEM. It was observed that systems showed modification in tensile impact properties. Optimum impact properties were shown at concentrations 6–8% of the block copolymer. At higher compositions there is deterioration in impact properties. High impact properties showed by these blends are attributed to the optimum level of compatibility achieved between the blend components. Tensile impact fracture studies revealed that failure pattern for these blend system transitioned from brittle to ductile fracture. Blends up to 10 wt% of block copolymer showed partially compatible heterogeneous nature exhibiting domain morphology. Blends with higher block copolymer content showed deterioration in tensile strength, modulus, yield strength, and tensile impact strength due to higher particle size of the agglomerated rubber soft segments of the block copolymer.     

Synthesis and characterization of poly(siloxane-urethane)s

A series of polyurethane block copolymers based on hydroxy-terminated polydimethylsiloxane and poly(propylene glycol) soft segments of molecular weights 1818 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′-diphenylnethane diisocyanate and 1,4-butanediol as the chain extender. Samples with different molar ratios were prepared. We tried to synthesize polydimethylsiloxane-based polyurethanes (PDMS-PU) containing a hard block as major fraction and a soft block as minor fraction for preparing toughened rigid systems. After a study of the pure polydimethylsiloxane-based polyurethane and poly(propylene glycol)-based polyurethane (PPG-PU), (mixed polyol)-based block copolymers and blends of PDMS-PU and PPG-PU were synthesized, and characterized by means of differential scanning calorimetry, tensile testing and scanning electron microscopy. In (mixed polyol)-based copolymers and lower hard-segment content blends, macro-phase separation occurred, but blends with higher hard-segment contents showed significant reduction in amounts of phase separation.     

Segmented block copolymers of natural rubber and 1, 3-butanediol–toluene diisocyanate oligomers

A series of segmented block copolymers of NR and 1,3-butanediol–toluene diisocyanate oligomers have been synthesized with varying hard segment content. The synthesis has been carried out by one-shot and two-shot processes in solution. The products were characterized by spectral analysis, thermal and mechanical analysis, SEM and optical microscopy. They are found to be amorphous materials having no potential for hydrogen bonding between the ‘hard' and ‘soft' segments. Their two-phase morphology has been deduced from SEM and optical micrographs and established by DMA and thermal studies. DSC analysis shows a soft segment glass transition temperature at −62±2°C and hard segment glass transitions between 70° and 100°C, depending on the polyurethane content. The T_g values determined by the dynamic mechanical analysis are significantly higher than these values.

The thermogravimetric analysis indicates a two-stage thermal decomposition of the materials by random nucleation mechanism and corresponds to the two phases present in the block copolymer. Depending on the proportion of the continuous and dispersed phases, the block coolymers behave like quasi-elastomers at lower hard segment concentrations and brittle plastics at higher hard segment contents. This variation in mechanical behaviour is consistent with the sample morphology. Materials synthesized by the two-shot process are found to possess better mechanical properties than the one-shot products, presumably due to a more systematic ordering of the different segments in the former.     

Segmented block copolymers of natural rubber and propylene glycol-toluene diisocyanate oligomers

Segmented block copolymers were synthesized from hydroxyl terminated liquid natural rubber (HTNR) and polyurethane oligomers based on 1,2-propylene glycol and toluene diisocyanate (TDI) by one-shot and two-shot processes in solution. They were completely phase segregated. Structural features were characterized by infrared and nuclear magnetic resonance spectroscopies. The two-phase morphology was deducted from thermal analysis and dynamic mechanical analysis (DMA). The soft segment glass transition temperature was about ?64°C and the hard segment glass transition was between 70°C and 100°C depending on the polyurethane content. The two-phase morphology was corroborated by a two-stage thermal decomposition of the products. The morphology consisted of a heterogeneous dispersion of beads in a continuous matrix. The large size and the nature of the beads suggest that they are independent of the block copolymer structure and are formed by the agglomeration of the polyurethane homopolymers, which remain unbonded to the rubber chains during chain extension. At lower hard segment contents the materials behaved like quasi-elastomers, and at higher hard segment contents, they were like tough plastics. At intermediate compositions they behaved as rigid elastomers. Variations in hardness and tear strength were consistent with this behavior.     

含氟二元胺为扩链剂的聚氨酯弹性体的合成和表征

以2,2-双(4-羟基苯基)六氟丙烷(全氟双酚A)为原料合成了2,2-双[4-(4-氨基苯氧基)苯基]六氟丙烷(BAPF6P),以此二元胺为扩链剂制备了一系列不同硬段含量的含氟聚氨酯弹性体(FPUE)。通过FTIR、TG、EA、WAXD、1H-NMR、DMA分析及拉伸试验,对BAPF6P和由其制备的FPUE的结构和性能进行了研究。结果表明,所得产物BAPF6P的结构与预期设计相符;由于FPUE的硬段间的强氢键作用和偶极效应,使得微区中部分链段排列有序形成微晶结构;随着硬段含量的提高,Tg逐渐升高,FPUE的耐寒性能逐渐降低,而耐热氧化性逐渐提高;FPUE的热分解温度在200℃以上,具有良好的耐热性能及优异的力学性能,BAPF6P是一个好的聚氨酯扩链剂。     

软段含离子基团的阴离子型水性聚氨酯胶粘剂的研究(Ⅱ)——硬段结构的影响

以含有不同离子基团的聚酯多元醇为软段,采用丙酮法合成了一系列水性聚氨酯乳液。研究了不同硬段结构和硬段含量和扩链剂对其干膜物理机械性能和吸水率的影响。     

有机硅/丁二醇扩链剂混合比对混合大二醇基聚氨酯弹性体的性能影响

以α,ω-双(γ-羟丙基)聚二甲基硅氧烷(BHPDMS)和聚氧四甲基二醇(PHMO)混合大二醇为软链段;以1,4-丁二醇(BDO)为主要扩链剂,1,3-双(4-羟丁基)-1,1,3,3-四甲基二硅氧烷(BHTD)为次级扩链剂,所有试样中硬链段均由4,4'-二苯基甲烷二异氰酸酯(MDI)和混合扩链剂所构成,且w(硬链段)=40%;采用两步溶液聚合法制备混合大二醇基芳香聚氨酯(PU)弹性体。通过力学性能测试、差示扫描量热法(DSC)和动力学热分析法(DMTA),研究了混合扩链剂中n(BDO)/n(BHTD)比值对该PU弹性体性能的影响。结果表明,当n(BDO):n(BHTD)=3:2时,所得PU弹性体具有优异的综合性能;引入BHTD扩链剂后,破坏了硬链段的有序性。     

Thermoplastic urethane elastomers IV. Effects of cycloaliphatic chain extender on dynamic mechanical properties

The dynamic mechanical properties of a series of thermoplastic urethane elastomers have been studied as a function of molecular composition and temperature. Polymers based on polycaprolactone diol, an isomeric mixture of tolylene diisocyanate and hydrogenated Bisphenol-A as the chain extender were prepared at various relative concentrations of hard and soft segments. The glass transition temperatures of these polymers progressively shifted to higher temperatures as the relative hard segment content was increased. This variation was accurately described by the Fox relationship for amorphous copolymers. These results can be interpreted in terms of the relative degree of segregation between the segment of the block copolymers.     

Pulsed nuclear magnetic resonance for studying phase separation in block and segmented copolymers

Pulsed nuclear magnetic resonance measurements have shown that segmented polyurethanes as well as block copolymers segregate into domains with distinct mobilities. The usefulness of this technique for investigating the importance of the domain interface and for studying the mixing/ demixing of domains has been demonstrated. By examining the percent rigid material as a function of temperature, a polystyrene/butadiene block copolymer showed little evidence of domain interface effects, while in a series of segmented polyurethanes, the interface was seen to be important. The domains of a polyester soft segment and diphenylmethane diisocyanate hard segment polyurethane were mixed by annealing at 170°C. Examination of the demixing process as a function of storage temperature enabled an activation energy for domain formation of 36 ± 5 kcal/mole to be calculated. In a series of polyurethanes with varying amounts of hard segments, the material with the least amount of hard segments showed evidence of soft segment crystallinity. The mixing proces in this series was interpreted in terms of shifting correlation frequency distributions.     

Thermoplastic polyurethanes with isosorbide chain extender

Isosorbide, a renewable diol derived from starch, was used alone or in combination with butane diol (BD) as the chain extender in two series of thermoplastic polyurethanes (TPU) with 50 and 70% polytetramethylene ether glycol (PTMEG) soft segment concentration (SSC), respectively. In the synthesized TPUs, the hard segment composition was systematically varied in both series following BD/isosorbide molar ratios of 100 : 0; 75 : 25; 50 : 50; 25 : 75, and 0 : 100 to examine in detail the effect of chain extenders on properties of segmented polyurethane elastomers with different morphologies. We found that polyurethanes with 50% SSC were hard elastomers with Shore D hardness of around 50, which is consistent with assumed co‐continuous morphology. Polymers with 70% SSC displayed lower Shore A hardness of 74–79 (Shore D around 25) as a result of globular hard domains dispersed in the soft matrix. Insertion of isosorbide increased rigidity, melting point and glass transition temperature of hard segments and tensile strength of elastomers with 50% SSC. These effects were weaker or non‐existent in 70% SSC series due to the short hard segments and low content of isosorbide. We also found that the thermal stability was lowered by increasing isosorbide content in both series. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42830.     

Rheological and mechanical properties of thermoplastic polyurethane elastomer derived from CO2 copolymer diol

CO₂ copolymer diol‐based thermal polyurethane elastomers (PPC‐TPU) were prepared by the reaction of CO₂ copolymer diol and methylene diphenyl diisocyanate and chain extender (ethylene glycol/1,4‐butanediol/1,6‐hexanediol) (EG/BDO/HG). The rheological and mechanical properties of PPC‐TPU were analyzed. The effects of shear rate, shear temperature, hard segment content, and variety of chain extender on the properties of PPC‐TPU were studied. The results showed that the apparent viscosity (η) of PPC‐TPU decreased with the increasing shear rate (τ), and the non‐Newtonian index (n) was less than 1. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. The degradation during the processing was obviously inhibited by adding plasticizer and antioxidant. It was also discovered that the apparent viscosity varied with the content of hard segment and chain extender. Under the same temperature (185 °C) and shear rate (50 s^?1), the apparent viscosity increased considerably with the raise of hard segment content, and the apparent viscosity and tensile strength of PPC‐TPU with EG as chain extender was the maximum. It can be seen that with the apparent shear rate increasing, the variation tendency of apparent shear stress levels off, and the nonlinear relationship of τ–γ curve tended to be obvious. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45974.     

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