聚氨酯/聚甲基丙烯酸酯交联聚合物合成与力学性能的研究

采用相对分子质量不同的聚氧化丙烯二醇(PPG)与甲苯二异氰酸酯合成聚氨酯预聚物,将该预聚物用甲基丙烯酸-2-羟乙酯(HEMA)封端后与甲基丙烯酸甲酯(MMA)、甲基丙烯酸丁酯(BMA)进行自由基聚合得到一系列交联聚合物。利用红外光谱(FT-IR)、力学性能测试及动态力学热分析(DMTA)等手段对交联聚合物进行了表征。聚氨酯/聚甲基丙烯酸甲酯(PU/PMMA)交联聚合物具有较高的阻尼值和较宽的阻尼温域,当两组分的质量比为5∶5时,阻尼性能最佳。PU/PMMA交联聚合物的拉伸强度随聚甲基丙烯酸甲酯含量的增加而增加,断裂伸长率随其含量的增加而减小;聚氨酯/聚甲基丙烯酸丁酯(PU/PBMA)交联聚合物的拉伸强度随聚甲基丙烯酸丁酯含量的增加而减小,断裂伸长率随其含量的增加而增大。     

Effect of the diisocyanate structure and the molecular weight of diols on bio‐based polyurethanes

Bio‐based polyurethanes (PU) containing poly(ε‐caprolactone) diol (PCL) and hydroxyl telechelic natural rubber (HTNR) were synthesized. The effect of the diisocyanate structure and the molecular weights of diols on the mechanical properties of PU were investigated. Three different molecular structures of diisocyanate were employed: an aliphatic diisocyanate (hexamethylene diisocyanate, HDI), an aromatic diisocyanate (toluene‐2,4‐diisocyanate, TDI) and a cycloalkane diisocyanate (isophorone diisocyanate, IPDI). Two molecular weights of each diol were selected. When HDI was employed, a crystalline PU was generated while asymmetrical structures of TDI and IPDI provided an amorphous PU. The presence of crystalline domains was responsible of a change in tensile behavior and physical properties. PU containing TDI and IPDI showed a rubber‐like behavior: low Young's modulus and high elongation at break. The crystalline domains in PU containing HDI acted as physical crosslinks, enhancing the Young's modulus and reducing the elongation at break, and they are responsible of the plastic yielding. The crystallinity increased the tear strength, the hardness and the thermal stability of PU. There was no significant difference between the TDI and IPDI on the mechanical properties and the physical characteristics. Higher molecular weight of PCL diol changed tensile behavior from the rubber‐like materials to the plastic yielding. Thermal and dynamic mechanical properties were determined by using DSC, TGA and DMTA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structure‐property relationship in polyurethane elastomers containing starch as a crosslinker

Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 ‐trimethylol propane (TMP) as the crosslinker. Starch‐based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch‐based PUs exhibited two glass transitions, whereas TMP‐based PUs exhibited one T_g. No significant difference in the T_gs of the two PUs was observed. The activation energy of St‐PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP.     

Biobased chain extended polyurethane and its composites with silk fiber

The biobased chain extended polyurethane (PU) was synthesized by reacting castor oil based polyol with different diisocyanates [toluene‐2,4‐diisocyanate (TDI) and hexamethylene diisocyanate (HMDI)] and chain extender such as glutaric acid. Biocomposites have been fabricated by incorporating the silk fiber into both TDI‐ and HMDI‐based PUs. The effect of incorporation of silk fiber into TDI‐ and HMDI‐based neat PU on the physicomechanical properties such as density, surface hardness, tensile strength, and percentage elongation have been investigated. The dynamic mechanical properties and the thermal stability of neat PUs and the silk fiber incorporated PU composites have been evaluated. The TDI‐based neat PU has showed higher mechanical properties compared to HMDI‐based PU. The incorporation of 10% silk fiber into TDI‐ and HMDI‐based PU resulted in an enhancement of tensile strength by 1.8 and 2.2 folds, respectively. The incorporation of silk fiber into biobased chain extended PU increased the glass transition temperature (T_g) of the resultant biocomposites. The morphology of tensile fractured neat PUs and their biocomposites with silk fiber was studied using scanning electron microscope (SEM). POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

E-300扩链聚氨酯弹性体的力学性能研究

以多元醇(PEA，PPG，PTMG)，PDI，E-300为原料，制备了PU弹性体。研究了多元醇类型，NCO基含量，扩链剂用量和硫化时间等因素对PU弹性体力学性能的影响。结果表明：拉伸强度、拉断伸长率和冲击弹性最高的分别是PEA-PU，PPG-PU和PTMG-PU；PU的硬度、强度和模量随预聚体NCO基含量增加而增加；扩链剂的用量为90％时，PU的力学性能最佳。     

交联对CO2共聚物为基聚氨酯降解性能的影响

讨论ＣＯ２ 共聚物为基聚氨酯聚碳酸亚乙酯聚氨酯（ＰＥＣＰＵ） 交联方式、交联程度对其生物降解性能的影响。实验结果显示,交联程度越大,降解速度有所降低,但一定交联程度的交联型ＰＥＣＰＵ仍然具有良好的生物降解性能。     

Effects of reaction and cure temperatures on morphology and properties of poly(ester‐urethane)

Poly(ester‐urethane) was synthesized from poly(ethylene glycol adipate) (PEG) and 2,4‐toluene diisocyanate (TDI) to study the effects of reaction temperature and cure temperature on the crystallization behavior, morphology, and mechanical properties of the semicrystalline polyurethane (PU). PEG as soft segment was first reacted with TDI as hard segment at 90, 100, and 110°C, respectively, to obtain three kinds of PU prepolymers, coded as PEPU‐90, PEPU‐100, and PEPU‐110. Then the PU prepolymers were crosslinked by 1,1,1‐tris (hydroxylmethyl) propane (TMP) and were cured at 18, 25, 40, 60, and 80°C. Their structure and properties were characterized by attenuated total reflection Fourier transform infrared, wide‐angle X‐ray diffraction, scanning electron microscopy, dynamic mechanical analysis, and tensile testing. With an increase of the reaction temperature from 90 to 100°C, the crystallinity degree of soft segment decreased, but interaction between soft and hard segments enhanced, leading to the increase of the glass transition temperature (T_g) of soft domain and tensile strength. When the cure temperature was above 60°C, miscibility between soft and hard segments of the PEPU films was improved, resulting in relatively low crystallinity and elongation at break, but high soft segment T_g and tensile strength. On the whole, all of the PEPU‐90, PEPU‐100, and PEPU‐110 films cured above 60°C possessed higher tensile strength and elongation at break than that of the films cured at other temperatures. The results revealed that the reaction temperature and cure temperature play an important role in the improvement of the crosslinking structure and mechanical properties of the semicrystalline PU. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 708–714, 2006     

Synthesis and characterization of poly(carbonate urethane) networks with shape‐memory properties

In this study, a series of shape‐memory polyurethanes were prepared from polycarbonate diol (PCDL) with a molecular weight of 2000, trimethylol propane, and isophorone diisocyanate (IPDI). The properties of crosslinked poly(carbonate urethane) (PCU) networks with various compositions were investigated. The chemical structures and thermal properties were determined with Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. FTIR analysis indicated that PCU had the structures of IPDI and PCDL and the amido formyl ester in polyurethanes. The gel content of PCU showed that PCU could be effectively formed as crosslinked polyurethane networks. The glass‐transition temperatures of the PCU networks increased slightly with decreasing soft‐segment content in the networks. The values of Young's modulus in the networks at 25°C increased with decreasing soft‐segment content, whereas the tensile stress and breaking elongation decreased significantly. PCU showed shape‐memory effects with a high strain fixity rate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of pyridazine content and crosslinker structure on the properties of polyurethane elastomers

This article studies the development of a series of heterocyclic polyurethanes (PUs) with various pyridazine content and different crosslinker structure in their main chains. All of the isocyanate‐terminated PU prepolymers were prepared from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6‐hexamethylene diisocyanate. The properties of the obtained linear and crosslinked pyridazine‐based PU were compared with the properties of common PUs obtained by chain extension with 1,4‐butanediol. All the obtained PUs were characterized through spectral and thermal behavior. The pyridazine‐based PU showed improved thermal stability with 10% weight loss at temperatures above 370–400°C. With the increase of pyridazine content the values of Young's modulus are higher and the strain at break decreases. Increasing pyridazine content leads to increased films surface hydrophilicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synergistic strengthening of composite films by crosslinking graphene oxide reinforcement and poly(vinyl alcohol) with dicarboxylic acids

High‐strength plastic materials with excellent biodegradability, non‐toxicity and economically wide availability are in high demand. Herein, we demonstrate graphene oxide (GO) composite of poly(vinyl alcohol) (PVA) as a potential bioplastic material by chemical crosslinking. For a potential bioplastic material, PVA has to be addressed for its high water absorbing capacity along with improvement in tensile strength and thermal stability. These issues were addressed by enhancing the interfacial binding between PVA and GO, covalent bonds between the two being introduced by crosslinking with dicarboxylic acids, namely succinic acid (SuA) and adipic acid (AdA). Crosslinking of neat PVA with dicarboxylic acids also resulted in enhanced swelling resistance and thermal stability. The greatest improvement in tensile strength and swelling resistance was observed for a GO crosslinked with diacids due to the synergistic effect of reinforcement and crosslinking. Improvements of 225 and 234% in the tensile strength of PVA (31.19 MPa) were observed for 5% GO–PVA samples crosslinked with 6.25 mmol AdA and 7.5 mmol SuA, respectively. For the same samples, water uptake was 44 and 29%, respectively, compared to the non‐crosslinked PVA (359%). © 2017 Society of Chemical Industry     

Damping properties of interpenetrating polymer networks of polyurethane‐modified epoxy and polyurethanes

Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)‐modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one‐shot method. Two types of PU‐modified epoxy: PU‐crosslinked epoxy and PU‐dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU‐modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU‐modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU‐modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU‐dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU‐crosslinked epoxy/PU IPNs with 20 wt % of PU‐crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999     

正交实验优选HTBN/聚氨酯合成的最佳工艺条件

以端羟基聚丁二烯-丙烯腈(HTBN)为软段、甲苯二异氰酸酯(TDI)为硬段和端氨基硅油为改性剂,合成了端氨基硅油改性HTBN型聚氨酯(PU)。以n(-NCO)∶n(HTBN)、n(硅油)∶n(HTBN)、n(扩链剂)∶n(HTBN)和硅油加入方式为主要影响因素,并以断裂伸长率、邵氏硬度、拉伸强度和定伸应力为考核指标,采用L9(34)正交实验方法优选该PU合成的最佳工艺条件。研究结果表明,当n(-NCO)∶n(HTBN)=1.6∶1、n(硅油)∶n(HTBN)=6∶100、n(扩链剂)∶n(HTBN)=5∶100且在后期加入端氨基硅油时,端氨基硅油改性HTBN型PU的综合性能最好。     

TIPA/BDO扩链的聚氨酯弹性体力学性能的研究

以聚酯(PEA、PEPA)或聚醚(PTMG)和TDI为原料合成聚氨酯(PU)预聚体,用三异丙醇胺(TIPA)和1,4-丁二醇(BDO)的混合物作扩链剂制备PU弹性体。讨论了软段相对分子质量、弹性体交联点相对分子质量和扩链剂的种类对PU弹性体性能的影响。结果表明,PU弹性体的硬度、拉伸强度、300%模量和撕裂强度随软段相对分子质量的增加而下降,而伸长率和冲击弹性随软段相对分子质量的增加而增加;交联点相对分子质量为6600时,PTMG2000为软段的PU弹性体的拉伸强度最高,达到28.44MPa;与TMP/BDO扩链的聚酯型PU弹性体相比,TIPA/BDO扩链的弹性体的拉伸强度、伸长率和撕裂强度均较高,而硬度、300%模量和冲击弹性差异不大。     

Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A new tri‐functional azetidine compound for self‐curing aqueous‐based PU system

A mono‐azetidine compound had been demonstrating a ring opening reaction with carboxylic acid (e.g., trimethylacetic acid, TMAA) and that resulted in an amino ester bond formation at ambient temperature. A triazetidine compound (trimethylolpropane tris(1‐azetidinyl)propionate, TMPTA‐AZT) was obtained via Michael addition of azetidine (AZT) to trimethylolpropane triacrylate (TMPTA). The carboxylic groups of anionic aqueous‐based polyurethanes (PU) served as internal emulsifier, which stabilized PU dispersion and also served as PU curing sites. The triazetidine compound (TMPTA‐AZT) was introduced into anionic aqueous‐based PU dispersion as a new latent curing agent and that mixture became a single‐component self‐curable aqueous PU system. A crosslinked PU film was obtained from this PU system on drying at ambient temperature. The final polymer performance properties demonstrated the crosslinking behaviors of this new curing agent, TMPTA‐AZT, with carboxylic ion‐containing aqueous‐based PU resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Improving the mechanical,thermal and electrical properties of polyurethane- graphene oxide nanocomposites synthesized by in-situ polymerization of ester-based polyol with hexamethylene diisocyanate

Many polyols or diols have been used for the synthesis of polyurethanes (PU), however, to the best of our knowledge, PU-graphene oxide (GO) nanocomposites synthesized with ester-based polyols have been rarely studied. In this work ester-based polyol synthesized by the reaction of adipic acid and 1,4 butane diol, was in-situ polymerized with hexamethylene diisocyanate (HDI) and GO to prepare PU-GO nanocomposites. The content of GO was changed from 1 to 2.5 wt% and its effect on the mechanical, thermal and electrical properties of the samples were examined. The presence of GO more than 1.5% in the nanocomposites resulted in brittle samples and reduced the tensile strength, however, the Young’s modulus of the samples containing 1 and 1.5% was increased to 11 and 12.08-fold (275 and 302 MPa) compared to the neat PU (25 MPa), respectively. The shore A hardness of the samples was increased from 86 for PU to 96 for PUGO-1.5. The abrasion resistance of the samples was decreased by increasing the GO content. Results of the thermogravimetric analysis showed that higher amounts of GO increase the thermal stability of the samples. The chemical and physical interactions between the surface of GO nanolayers and the PU chains were confirmed by FTIR spectroscopy. The dynamic mechanical analysis of the samples showed that GO nanolayers decreased the molecular motions of the PU chains in the nanocomposites which were noticed by shifting the glass transition to the higher temperatures.     

Respective Contribution Research of Soft Component and Macroinitiator on Synthesis and Performance of MCPA‐PEA Materials

The monomer casting polyamide‐polyether amine (MCPA‐PEA) materials initiated by TDI‐PEA macroinitiator presented an obvious toughness characteristic which was contributed by the combination effect of PEA‐TDI macroinitiator and soft PEA component itself. The MCPA‐PEA materials with different content of PEA‐TDI macroinitiator or PEA component were prepared and then the respective contribution of PEA‐TDI macroinitiator and soft PEA component on the synthesis and performance were researched. It was found that the PEA‐TDI macroinitiator presented the dominant contribution and main influence on the polymerization process with higher activation energy and reaction order than PEA component. The PEA molecular chains did not participated in the crystallization process and made no influence on crystal structure of MCPA material whatever the way of copolymerization or blending. The PEA‐TDI macroinitiator also showed the dominant contribution on the decreasing effect of crystallization properties than PEA component with lower crystallinity and smaller spherulites size. The fibrous‐structure for MCPA‐0.3%PEA matrix was more obvious with notable deformation and high impact strength which further indicated the dominant contribution of PEA‐TDI macroinitiator on toughness. The toughening mechanism was deduced as the vast energy consumption by intense extension of fibrous‐structure and the highly orientation of molecular chains. POLYM. ENG. SCI., 58:1353–1361, 2018. © 2017 Society of Plastics Engineers     

Polyurethanes from benzene polyols synthesized from vegetable oils: Dependence of physical properties on structure

Asymmetric and symmetric aromatic triol isomers were synthesized from erucic acid. The pure asymmetric and symmetric triols were crosslinked with MDI into their corresponding polyurethane sheets. The physico‐chemical properties of these polyurethanes were studied by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis coupled with Fourier transform infrared (TGA‐FTIR) spectroscopy, and tensile analysis. The A‐PU and S‐PU demonstrated differences in their glass transition temperatures (T_g) and crosslinking densities. The difference in T_g of these polyurethanes could be explained by the differences in crosslinking densities, which could be related to the increase in steric hindrance, to the crosslinking MDI molecules, between adjacent hydroxyl groups of the asymmetric triol monomers. Overall, it was found that both polyurethanes had similar mechanical and thermal properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermomechanical characteristics of benzoxazine–urethane copolymers and their carbon fiber‐reinforced composites

Copolymers of polybenzoxazine (BA‐a) and urethane elastomer (PU) with three different structures of isocyanates [i.e., toluene diisocyanate (TDI), diphenylmethane diisocyanate, and isophorone diisocyanate], were examined. The experimental results reveal that the enhancement in glass transition temperature (T_g) of BA‐a/PU copolymers was clearly observed [i.e., T_g of the BA‐a/PU copolymers in 60 : 40 BA‐a : PU system for all isocyanate types (T_g beyond 230°C) was higher than those of the parent resins (165°C for BA‐a and ?70°C for PU)]. It was reported that the degradation temperature increased from 321°C to about 330°C with increasing urethane content. Furthermore, the flexural strength synergism was found at the BA‐a : PU ratio of 90 : 10 for all types of isocyanates. The effect of urethane prepolymer based on TDI rendered the highest T_g, flexural modulus, and flexural strength of the copolymers among the three isocyanates used. The preferable isocyanate of the binary systems for making high processable carbon fiber composites was based on TDI. The flexural strength of the carbon fiber‐reinforced BA‐a : PU based on TDI at 80 wt % of the fiber in cross‐ply orientation provided relatively high values of about 490 MPa. The flexural modulus slightly decreased from 51 GPa for polybenzoxazine to 48 GPa in the 60 : 40 BA‐a : PU system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Properties of crosslinked blends of pellethene and multiblock polyurethane containing poly(ethylene oxide) for biomaterials

A series of multiblock polyurethanes, containing various poly(ethylene oxide) (PEO; number‐average molecular weight = 400–3400) contents (0–80 wt %) and prepared from hexamethylene diisocyanate/PEO/poly(dimethylsiloxane) diol/polybutadiene diol/1,4‐butanediol, were used as modifying additives (30 wt %) to improve the properties of biomedical‐grade Pellethene. Different molecular weights of PEO were used to keep poly(ethylene glycol) at a fixed molar content, if possible, although the PEO content, related to the PEO block length in the multiblock polyurethanes, was varied from 0 to 80 wt %. The hydrophilic PEO component was introduced through the addition of PEO‐containing polyurethanes and dicumyl peroxide as a crosslinking agent in a Pellethene matrix. As the PEO content (PEO block length) increased, the hydrogen‐bonding fraction of the crosslinked Pellethene/multiblock polyurethane blends increased, and this indicated an increase in the phase separation with an increase in the PEO content in the crosslinked Pellethene/multiblock polyurethane blends. According to electron spectroscopy for chemical analysis, the ratio of ether carbon to alkyl carbon in the crosslinked Pellethene/multiblock polyurethane blends increased remarkably with increasing PEO content. The water contact angle of the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased with increasing PEO content. The water absorption and mechanical properties (tensile modulus, strength, and elongation at break) of the crosslinked Pellethene/multiblock polyurethane blend films increased with increasing PEO content. The platelet adhesion on the crosslinked Pellethene/multiblock polyurethane blend film surfaces decreased significantly with increasing PEO content. These results suggest that crosslinked Pellethene/multiblock polyurethane blends containing the hydrophilic component PEO may have potential for biomaterials that come into direct contact with blood. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2348–2357, 2004