聚氨酯/环氧树脂互穿网络聚合物反应动力学

通过共混法制备了聚氨酯(PU)/环氧树脂(EP)互穿网络聚合物(IPN),采用示差扫描量热法(DSC)和动态机械分析(DMA)对IPN形成过程中的固化反应动力学及产物IPN的相容性进行了研究,结果表明,m(PU)/m(EP)=10∶6的IPN体系的反应级数为0.95,表观活化能为169.23 kJ/mol;PU/EP IPN只有1个玻璃化转变温度,相容性好。     

聚氨酯/乙烯基树脂互穿聚合物网络的研究进展

综述了聚氨酯/乙烯基树脂互穿聚合物网络（PU/VER IPNs）中两组分的聚合机理;重点讨论了分步IPNs、同步IPNs和胶乳IPNs的制备方法及其研究进展;介绍了PU/VER IPNs合成动力学的研究方法,包括化学滴定法、差示扫描量热法和傅立叶变换红外光谱法。     

三（2-羟乙基）异氰脲酸酯改性TDI-80对PUE性能的影响

用三（2-羟乙基）异氰脲酸酯（THEIC,赛克）和TDI-80反应,得到改性异氰酸酯,从而把异氰脲酸酯（IS）环引入到聚氨酯弹性体（PUE）的分子主链。通过改变赛克的用量,考察其对PUE的力学性能和耐热性能的影响。力学性能测试结果表明：当赛克质量分数为10％时,PUE的拉伸强度和拉断伸长率达到了最高值,分别为46MPa和732％。DSC和TG测试结果表明：引入IS环后,PUE的耐热性能有所提高。DMA测试结果表明：改性PUE的内耗峰比未改性的宽,并且内耗峰值所对应的温度提高（由10℃提高到60℃）。     

耐热型聚氨酯弹性体的合成

催化合成了甲苯二异氰酸酯的部分三聚体异氰脲酸酯,然后与聚醚二元醇反应,用二步法手工浇注成异氰脲酸酯改性的聚氨酯弹性体。用红外光谱法证实了产物中异氰脲酸酯的存在。根据用二正丁胺法测得的NCO基团的质量分数可计算出异氰脲酸酯的质量分数,用热重法分析了产物的热稳定性。结果表明,与普通聚氨酸弹性体相比,合成的改型聚氨酯弹性体的热稳定性得到了明显提高。     

互穿聚合物网络技术在聚氨酯中的应用

综述了互穿聚合物网络(IPN)技术在聚氨酯材料中的应用研究进展。简述了聚氨酯IPN的制备,具体叙述环氧树脂、聚丙烯酸酯、聚硅氧烷、乙烯基酯树脂等聚合物与聚氨酯互穿网络改性的效果,并在此基础上展望了聚氨酯互穿网络聚合物的发展趋势。     

Mechanical and morphological study of polyurethane/polystyrene interpenetrating polymer networks containing ionic groups

The viscoelastic and mechanical properties and the morphology of polyurethane (PUR)/ olystyrene (PS) interpenetrating polymer networks (IPNs) containing ionic groups have been investigated. Dynamic mechanical thermal analysis (DMTA) revealed a pronounced change in the viscoelastic properties upon the introduction of ionic groups. For the 70 : 30 and 60 : 40 PUR/PS IPN compositions, the DMTA data changed from a dominant PUR to a dominant PS loss factor peak. Higher intertransition loss factor values indicated a significant improvement of IPN component mixing with increasing ionic content. The stress at break values increased only moderately, whereas sharp rises in Young's modulus and hardness values were found at 2 wt % ionic groups. At the same time, the strain at break values decreased by half. Scanning and transmission electron microscopy (TEM) indicated a grossly phase-separated morphology for the 70 : 30 PUR/PS IPN without ionic groups. With increasing methacrylic acid (MAA) content, the PS phase domain sizes decreased. At 2 wt % of ionic groups, a TEM micrograph showed interconnected PS phase domains resembling a network structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1973–1985, 1998     

Synthesis and characterization of polyurethane/polybenzoxazine‐based interpenetrating polymer networks (IPNs)

Sequential interpenetrating polymer networks (IPNs), based on polyurethane and polybenzoxazine, were synthesized. Fourier Transform infrared spectrometry was employed to monitor the formation kinetics, which indicated that only physical bonding existed in the resulting IPNs. Morphological investigations revealed a lightly phase separation behaviour in all of the IPNs studied. © 2003 Society of Chemical Industry     

AB‐type crosslinked polymer networks from vinyl terminated polyurethane and poly(methyl methacrylate)

Vinyl terminated polyurethanes (VTPUs) were prepared by endcapping isocyanate terminated prepolymers with vinylbenzyl alcohol (VBA). AB‐type crosslinked polymer (ABCP) networks were generated by crosslinking the telechelic polyurethane with methyl methacrylate (MMA) in the presence of 2,2′‐azobisisobutyronitrile (AIBN) as free radical initiator. The spectral, thermal and mechanical properties of ABCPs were studied using Fourier Transform IR, thermogravimetry, dynamic mechanical analysis and stress‐strain analysis. The FTIR results confirm the formation of VBA, TP and ABCPs. Thermal behaviour of crosslinked polymers showed no significant weight loss up to 300 °C, indicating improved thermal stability. Dynamic mechanical tests revealed confinement of phase separation and good damping behaviour for the crosslinked networks. Stress‐strain analysis showed that tensile strength increases with increasing amounts of methyl methacrylate. © 2001 Society of Chemical Industry     

High-resolution thermogravimetric analysis of polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks

Thermal degradation of a series of polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks and their constituent networks were studied by three modes of thermogravimetric analysis: the conventional method, the constant reaction rate method, and the dynamic rate technique. The best understanding of the degradation mechanism was achieved by the last method, which allows much better resolution of overlapping events. In addition, the weight losses correspond well with the results obtained from the constant reaction rate analysis, but are achieved in shorter times. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 287–295, 1998     

聚氨酯/聚甲基丙烯酸甲酯互穿网络的阻尼性能及相态

引言聚合物互穿网络体系由于在其形成过程中产生特殊的物理拓扑结构,使得该体系是一种永久缠结在一起的聚合物"合金"[1]。同时,由于构成该体系的聚合物组分往往不相容或部分相容,在其形成     

PU/BA-HEMA互穿网络型聚合物的合成及性能

以异佛尔酮二异氰酸酯（IPDI）、二羟甲基丙酸（DMPA）为硬段,聚醚多元醇（N220）为软段,以丙烯酸丁酯（BA）和甲基丙烯酸羟乙酯（HEMA）改性,制备了水性聚氨酯（PU）分散液,测定了水分散液及其膜的物理性能和力学性能。结果表明,与未改性的PU水分散液相比,改性聚氨酯水分散液的粒径均有所增大,表面张力减小,力学性能和硬度提高。HEMA 的引入,形成了具有化学交联的核-壳互穿网络结构的聚合物,说明改性材料中分子链硬段与PA分子链具有较高的相容性。     

不变黄HDI型聚氨酯/聚甲基丙烯酸甲酯互穿网络胶粘剂的研究

制备了不变黄HDI(1,6-己二异氰酸酯)型聚酯聚氨酯/聚甲基丙烯酸甲酯(PMMA)互穿网络胶粘剂,探讨了甲基丙烯酸甲酯(MMA),单体用量、引发剂用量、反应温度和反应时间等条件对其胶液粘度和初粘力的影响,并成功作为制鞋工业用胶。     

Miscibility and thermal and dynamic mechanical behaviour of semi‐interpenetrating polymer networks based on polyurethane and poly(hydroxyethyl methacrylate)

The thermodynamic miscibility and thermal and dynamic mechanical behaviour of semi‐interpenetrating polymer networks (semi‐IPNs) of crosslinked polyurethane (PU) and linear poly(hydroxyethyl methacrylate) (PHEMA) have been investigated. The free energies of mixing of the semi‐IPN components have been determined by the vapour sorption method and it was established that the parameters are positive and depend on the amount of PHEMA in the semi‐IPN samples. Thermal analyses glass transition temperatures evidenced two in the semi‐IPNs in accordance with the investigation of the thermodynamic miscibility of these systems. Dynamic mechanical analysis revealed a pronounced change in the viscoelastic properties of the PU‐based semi‐IPNs with different amounts of PHEMA in the samples. The semi‐IPNs have two distinct tan δ maxima related to the relaxations of the two polymers in their glass temperature domains. The temperature position of PU relaxation maximum tan δ is invariable but its amplitude decreases in the semi‐IPNs with increasing amount of PHEMA in the systems. The tan δ maximum of PHEMA is shifted to a lower temperature and its amplitude decreases with increasing amount of PU in the semi‐IPNs. The segregation degree of components α was calculated using the viscoelastic properties of semi‐IPNs. It was concluded that the studied semi‐IPNs are two‐phase systems with incomplete phase separation. The different levels of immiscibility lead to the different degree of phase separation in the semi‐IPNs with compositions. Copyright © 2004 Society of Chemical Industry     

Graft interpenetrating polymer networks of polyurethane and epoxy containing rigid rods in side chain

The rigid rod‐like 4,4′‐bis(6‐hydroxyhexyloxy)biphenyl (BHHBP) units were distributed in either the epoxy or polyurethane to become SR‐epoxy and PU (with or without BHHBP) polymer matrices. The interpenetrating polymer networks (IPNs) of PU (with or without BHHBP) and SR‐epoxy were synthesized through simultaneous polymerization, and connected each other via the grafting reaction between the ? NCO groups of the PU polymer network and the ? OH groups on the side chains of SR‐epoxy network. The thermal and mechanical characteristics, compatibilities, and morphologies of these PU (with or without BHHBP)/SR‐epoxy graft‐IPNs were investigated. The polyether‐type PU(PPG series)/SR‐ epoxy graft‐IPNs exhibited two‐phased morphologies (i.e., phase separation occurred), and higher fracture energies (G_IC). Whereas the polyester‐type PU(PBA series)/SR‐ epoxy graft‐IPNs were homogeneous (no phase separation), and exhibited higher tensile and Izod impact strengths. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Carboxylated polyurethane anionomers and their composites with polypyrrole

Some polyurethane anionomers synthesized by a two‐step substitution postreaction of urethane hydrogen atoms with CH₂COONa groups were studied. The influence of ionic structures on the mechanical and electrical properties of polymers was followed. The carboxylated polyurethane anionomers were used to obtain electroconductive composites with polypyrrole, by immersion of polyurethane films in aqueous solution of pyrrole and oxidative chemical polymerization of the heterocyclic monomer with FeCl₃. The proportion of polypyrrole in the composites increased by introduction of ionic groups. Stress–strain behavior and electrical conductivity of composites were compared with those of the anionomers. Incorporation of polypyrrole significantly enhanced the electrical conductivity but diminished mechanical properties. Some composites possess both satisfactory conductivity and mechanical properties. The results were explained by the morphological changes induced by ionic group and polypyrrole presence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1385–1392, 2000     

Second order non-linear optical interpenetrating polymer networks based on polyurethane or poly(methyl methacrylate) and epoxy polymer

Two interpenetrating polymer networks (IPNs), (one pseudo-IPN consisting of a linear polyurethane/epoxy-based polymer network and one full-IPN consisting of a poly(methyl methacrylate)/epoxy-based polymer network) have been synthesized and characterized. Both IPNs showed only one T_g; hence a homogeneous phase morphology is suggested. The second-order non-linear optical coefficients (d₃₃) of the pseudo-IPN and the full-IPN were measured and found to be 2.78 × 10⁻⁷ esu and 1.86 × 10⁷ esu, respectively. The study of temporal stability at room temperature and elevated temperature (120 °C) indicates that the full-IPN is more efficient at improving the orientational stability of the non-linear optical chromophores than the pseudo-IPN, because of the permanent entanglements of the two component networks in the full-IPN. © 1999 Society of Chemical Industry     

Synthesis and properties of novel polyurethane acrylate containing 3-(2-hydroxyethyl) isocyanurate segment

Novel UV curable multi-functional polyurethane acrylate (PUA) containing 3-(2-hydroxyethyl) isocyanurate (THEIC) segment was synthesized through three step reactions, the ring-opened reaction of ?-caprolactone with THEIC under the catalysis of tetrabutyl titanate (TBT), the polyaddition reaction between formed hydroxyl compounds and isophorone diisocyanate (IPDI) and condensation reaction between the product of the second step and pentaerythritol triacrylate (PETA). The chemical structure of PUA oligomer and some influence factors in synthesis process were characterized with GPC, ¹H NMR and FTIR. And its photopolymerization process and properties of cured films were also investigated.     

Synthesis and characterization of polyurethane anionomers

Un‐ionized polyurethane was obtained by the reaction of an isocyanate‐terminated urethane prepolymer, which was synthesized from 4,4′‐diphenylmethane diisocyanate and poly(oxytetramethylene)‐α,ω‐glycol, with 2,2‐bis(hydroxymethyl)propionic acid. A carboxylate‐based polyurethane anionomer was then derived from the polyurethane by the use of the sodium, potassium, or magnesium salt of acetic acid as a neutralizer. The ionomerization resulted in the following changes in the characteristics of the polyurethane: (1) an increase in the tensile strength, (2) a decrease in the glass‐transition temperature, (3) an increase in the wettability and hygroscopicity with respect to water, and (4) susceptibility to thermal decomposition. A sulfonate‐based polyurethane was also synthesized for comparison with the carboxylate‐based polyurethane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2144–2148, 2005     

Nanoclay reinforced rigid polyurethane foams

Clay was intercalated and exfoliated by neutralized dimethylol butanoic acid (DMBA) and used to fabricate rigid polyurethane foam (RPUF)/clay nanocomposites. Cream time, gel time, and tack‐free time increased with the addition and increasing amount of clay whereas foam density and compression strength decreased. Cell size, closed cell content, volume change upon heating and cooling, and thermal conductivity of the foam decreased with the addition and increasing amount of clay with a minimum at 2 pphp (parts per 100 polyol by weight). The glass transition and decomposition temperatures increased with increasing clay content due to the restricted motion of chains and barrier property of the clay platelets. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of crosslinking density on the physical properties of interpenetrating polymer networks of polyurethane and 2-hydroxyethyl methacrylate-teminated polyurethane

Interpenetrating polymer networks (IPNs) of 2-hydroxyethyl methacrylate-terminated polyurethane (HPU) and polyurethane (PU) with different crosslinking densities of the PU network were prepared by simultaneous solution polymerization. Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) show that compatibility of component polymers in IPN formation depends on the crosslinking density of the PU network. Physical properties such as density and water absorption rely on the subtle balance between the degree of phase separation and the crosslinking density of the PU network. In spite of the occurrence of phase separation, the tensile moduli and tensile strength of the IPNs increase with the crosslinking density of the PU network. Morphological observation by scanning electron microscopy revealed different fracture surfaces between the compatible and incompatible IPNs. Surface characteristics of the IPNs, indicated as hydrogen bonding index and hard-to-soft segment ratio, are altered considerably by varying surface morphologies. Improved blood compatibility of IPN membranes is due to the variation of the hydrophilic and hydrophobic domain distribution.