水性聚氨酯／丙烯酸酯复合细乳液的研究

用细乳液聚合的方法制备水性聚氨酯／丙烯酸酯复合细乳液,研究了引发剂的种类与用量对乳液的影响,并对胶膜进行热重分析,同时根据实验标准测试胶膜的拉伸强度和剥离强度。实验表明：PU加入量为15％时,胶膜拉伸强度提高23％,此处的断裂伸长率和剥离强度也达到了最大值。     

双组分聚氨酯胶粘剂的研制

以改性聚醚多元醇、MDI预聚体和改性轻质碳酸钙为原料,制备了双组分聚氨酯胶粘剂.实验结果表明,改性CaCO3对PU胶具有增强作用,在CaCO3添加量为10％左右时,其增强效果最好,拉伸强度达11MPa;当CaCO3深加量为20％时断裂伸长率达到最大值165％;PU／CaCO3复合体系中CaCO3颗粒分散均匀.     

麦草氧碱木素合成聚氨酯及其性能的研究

利用麦草氧碱木素取代部分聚乙二醇合成了木素 聚醚型聚氨酯 ,对其热性能、机械性能进行了初步研究。结果表明 ,麦草氧碱木素可取代部分聚乙二醇与二苯甲基二异氰酸酯合成木素 聚醚型聚氨酯 ,异氰酸基指数和木素含量对合成的木素 聚醚型聚氨酯性能有着重要影响     

PU/OMMT纳米复合材料的制备与性能研究

采用一步法和预聚体法制备聚氨酯（PU）／有机蒙脱土（OMMT）纳米复合材料，研究分散方式对OMMT层间距以及复合材料制备方法和OMMT用量对纳米复合材料拉伸性能的影响。结果表明，采用高速剪切分散法和超声波分散法均可使聚四氢呋喃醚二醇分子链进入OMMT片层间，增大其层间距；预聚体法PU／OMMT纳米复合材料拉伸性能优于一步法复合材料；与PU弹性体相比，当OMMT用量为0．5份时，一步法复合材料的强度和韧性均提高。牌号为DKIN的OMMT用量为7份时。复合材料的拉伸强度提高54％，拉断伸长率提高19．4％，增幅最大。     

乙酸木质素-聚醚型聚氨酯的合成及其特性研究

用红外光谱研究了乙酸木质素的结构。以乙酸木质素代替部分聚乙二醇合成了聚醚型聚氨酯。采用TGA、DSC和拉伸实验对乙酸木质素合成的聚氨酯进行了热性能和机械性能的研究。结果表明：乙酸木质素具有典型的聚多元醇结构，虽然有部分被乙酰化，但它具有很好的溶解性；用木质素作原料合成的聚氨酯与典型的纯PEG型聚氨酯相比，木质素的添加使聚氨酯的玻璃化转变温度升高和在600℃以下的分解率下降，改善了聚氨酯的耐热性能；同时，添加乙酸木质素的聚氨酯的强度和伸长率与纯PEG型聚氨酯低相比有所下降。     

木素—聚醚型聚氨酯的合成与性能

利用低污染的氧碱制方法制取的麦草氧碱木素合成了木素－聚醚型聚氨酯，对其热性能、力学性能进行了研究。结果表明，麦草氧碱木素可取代部分聚乙二醇与二苯甲基二异氰酸合成木素－聚醚型聚氨酯；异氰酸指数和木素含量对合成的木素－聚醚型聚氨酯性能有影响。     

硅丙乳液与聚氨酯乳液的复合改性

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸羟丙酯、丙烯酸、乙烯基硅油为原料,采用种子乳液聚合法合成了硅丙乳液;以甲苯二异氰酸酯、聚醚二元醇、二羟甲基丙酸(DMPA)为原料,合成了聚氨酯乳液。并用聚氨酯乳液与硅丙乳液进行复配改性。研究了乙烯基硅油用量对硅丙乳液性能及复合乳胶膜性能的影响、DMPA用量及n(—NCO)∶n(—OH)值对聚氨酯乳液性能的影响、聚氨酯用量对复合乳胶膜的拉伸强度、断裂伸长率、粘接强度的影响。结果表明,制备硅丙酯乳液的较佳配比是乙烯基硅油的质量分数8%,m(BA)∶m(MMA)=3∶2;制备聚氨酯乳液的较佳配比为n(—NCO)∶n(—OH)=1.15~1.3,DMPA的质量分数为6%;聚氨酯乳液的质量分数为20%时,复合乳胶膜的粘接强度、拉伸强度和扯断伸长率分别提高86.7%、32.8%和24.9%。     

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。     

桉木木素的付立叶变换红外光谱研究

付立叶变换红外光谱是分析木素结构的一种有效手段。本研究用付立叶变换红外光谱法分析了桉木分离木素和桉木原本木素，并对两者进行了比较。结果表明桉木磨木木素由愈创木基和紫丁香基组成，其中紫丁香基占40％～45％，愈创木基占55％～60％，甲氧基含量为每C9单元1．40个左右。与杉木和山毛榉相比，桉木磨木木素中含有较多的乙酸基和共轭羰基，并且含有一定量的芳香酸的酯类。用差示光谱法对桉木原本木素进行了研究，结果表明原本木素比磨木木素含有更多的氢键联接和乙酸基，但原本木素中的α-羰基含量较少，紫丁香基结构单元的比例也较小，结果还表明磨木木素可能更多地来源于木材纤维细胞次生壁。     

二氧化钛对聚氨酯抗紫外性能影响的研究

采用二氧化钛(Ti O2)为光稳定剂,制备了Ti O2/聚氨酯(PU)复合材料,并通过红外光谱分析和力学性能测试研究了紫外老化时间对纯PU材料和Ti O2/PU复合材料分子结构以及力学性能的影响。结果表明,纯PU分子链中醚键发生了氧化降解,老化后的纯PU力学性能降低。而Ti O2/PU复合材料的拉伸强度和扯断伸长率均有不同程度的提高,当Ti O2质量分数为5%~10%时,力学性能达到最佳,随着Ti O2用量的增加,Ti O2/PU复合材料的氧化降解程度逐渐减弱,材料黄变指数逐渐降低,当Ti O2质量分数为20%时,黄变指数降幅达41.5%。     

Properties and structure of PVP–lignin “blend films”

Blend films of poly (4‐vinylpyridine) and lignin were prepared by the casting method. Their structure and properties were studied by Fourier transform infrared (FTIR), wide‐angle X‐ray diffraction (WXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). The IR spectra of the blend films indicated that hydrogen‐bonding interaction occurred between poly (4‐vinylpyridine) and lignin. The glass transition temperature of these blends increased with the increase of lignin content, which indicated that these blends were able to form a miscible phase due to the formation of intermolecular hydrogen bonding between the hydroxyl of lignin and the pyridine ring of poly (4‐vinylpyridine). The thermostability of these blends decreased with the increase of lignin content. Initially, an appreciable increase in the measured tensile strength was achieved with a lignin content of 15%, at which the maximum value of 33.03 MPa tensile strength was reached. At a 10% lignin incorporation level, the blend film exhibited a maximum value of 9.03% strain. When the threshold in lignin content for blend films exceeded that limit of 10% lignin, the strain behavior of these blend films deteriorated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1405–1411, 2005     

高沸醇木质素聚氨酯的合成及其性能

利用高沸醇(H igh Boiling Solvent,HBS)木质素替代部分聚醚二元醇直接与甲苯二异氰酸酯(TD I)合成聚氨酯,对木质素聚氨酯样片的力学性能和耐溶剂性能进行了研究,并进行了热重(TG)分析。结果发现,当w(木质素)<10%时,聚氨酯有良好的弹性,而拉伸强度低于10 MPa;w(木质素)=15%~25%时,聚氨酯的拉伸强度提高到16 MPa或更高,其溶胀质量增加率降到84%以下;木质素聚氨酯的拉伸强度随n(NCO)/n(OH)值的增大而迅速增强;当w(木质素)>30%时,无论n(NCO)/n(OH)值为多少都得到了硬、脆的聚氨酯;采用相对分子质量较低的聚醚二元醇合成的木质素聚氨酯的拉伸强度可提高到36 MPa以上,其断裂伸长率并不明显降低,甚至在n(NCO)/n(OH)<1.6时反而更高,而溶胀质量增加率则降到1.25%。热重(TG)分析表明,HBS木质素的引入提高了聚氨酯的耐热性,其400℃以下的分解百分率下降了12.94%。     

MOLECULAR WEIGHT EFFECTS OF THE SOFT SEGMENT ON THE ULTIMATE PROPERTIES OF LIGNIN-DERIVED POLYURETHANES

Polyurethane (PU) films were prepared by solution casting using a three-component system, namely a novel semi-rigid solvolytic lignin, soft segment and a co-monomer. In the present study, the effects of varying the chain length of polyethylene glycol (as the soft segment) were investigated to produce lignin-based polyurethanes with variable thermal and mechanical properties. An important objective was to incorporate as much lignin as possible. The polyethylene glycol (PEG) studied included 5 different molecular weights (200, 400, 1000, 1500 and 2000 g/mol). The polyurethane films, prepared by solvent casting, were evaluated for crosslink density, and ultimate mechanical and thermal properties. Results showed that the films derived from the PEG 200 were either too weak or brittle to be tested. It was found that the PEG (400, 1000, and 1500) are better choices for producing polyurethanes from the solvolysis lignin studied. Crosslink densities of PU films using the 400, 1000 and 1500 were determined to be in the range of 0.8–2.6 mmol/cm³, which is a lower range than those of films from PEG 2000, namely 2.4–2.8 mmol/cm³. Also, the ultimate tensile strength decreased from about 50 MPa at high lignin content for PEG 400, 1000 and 1500 to about 18 MPa for PEG 2000 at low content of lignin. Ultimate strain also decreased from the 30.9–62.7% range for the PEG 400 to 1500 series at low lignin content down to about 4% for PEG 2000 at high lignin content. Young's Modulus varied from a high of 2 GPa (PEG 400, lignin content = 30 wt%) down to 0.6 GPa (PEG 2000, lignin content = 20 wt%). The glass transition temperature was found to decrease from 108°C to about 45°C with increasing molecular weight of PEG for a lignin content of 30 wt% and an NCO/OH of 1.2. The data are consistent with the percolation theory approach to network formation, as well as the notion that the network itself consists of relatively large and stiff islands, each comprising many branch points, held together by a soft and pliable matrix.     

Structure and properties of casting films blended with starch and waterborne polyurethane

A series of casting films blended from starch and waterborne polyurethane (STPU) in aqueous solution were prepared. The structure and properties of the films were investigated by infrared spectroscopy, ultraviolet spectroscopy, scanning electron micrography, strength test, thermogravimetric analysis, and different scanning calorimetry. The results showed that the tensile strength and modules of air‐dried STPU blend films increased with the increase of starch content, while elongation decreased. When starch content was in the range from 80 to 90 wt %, the blend films showed significantly higher tensile strength, breaking elongation, water resistivity, and light transmittance than that of pure starch film, resulting from the miscibility between starch and waterborne polyurethane. Moreover, the STPU films containing 90 wt % starch have higher thermal stability than pure waterborne polyurethane film, and their light transmittance was close to the polyurethane, due to the existence of a strong intermolecular hydrogen bonding between starch and polyurethane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2006–2013, 2001     

Preparation and colloidal properties of an aqueous acetic acid lignin containing polyurethane surfactant

Aqueous acetic acid lignin containing polyurethane (ALPU) surfactants were prepared by the replacement of some hydrophobic poly(caprolactone diol) with different concentrations of multifunctional acetic acid lignin (AL), and with dimethylol propionic acid as the hydrophilic segment. The infrared spectra, together with thermogravimetric analysis, demonstrated the presence of AL in the polyurethane (PU) chains. In addition, the effects of the AL concentration on the particle size, morphology, rheological behavior, and surface activity of the dispersions were investigated. The ALPU particles displayed a spherical morphology. With increasing AL concentration from 0 to 10 wt %, the particle size increased from 36 to 260 nm, and the unimodal distribution was detected for ALPU₁₀ with a 10 wt % AL addition. The viscosity and shear‐thinning behavior of the ALPU dispersions decreased, and the lowest surface tension and critical micelle concentration (cmc) were detected for ALPU₁₀. However, when the AL concentration was 15 wt % (ALPU₁₅), the surface tension and cmc increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1855–1862, 2013     

Development of stiff, strong, yet tough composites by the addition of solvent exfoliated graphene to polyurethane

We have prepared graphene dispersions, stabilised by polyurethane in tetrahydrofuran and dimethylformamide. These dispersions can be drop-cast to produce free-standing composite films. The graphene mass fraction is determined by the concentration of dispersed graphene and can be controllably varied from 0% to 90%. Raman spectroscopy and helium ion microscopy show the graphene to be well-dispersed and well-exfoliated in the composites, even at mass fractions of 55%. On addition of graphene, the Young’s modulus and stress at 3% strain increase by ×100, saturating at 1 GPa and 25 MPa, respectively, for mass fractions above 50 wt%. While the ultimate tensile strength does not vary significantly with graphene content, the strain at break and toughness degrade heavily on graphene addition. Both these properties fall by ×1000 as the graphene content is increased to 90 wt%. However, the rate of increase of Young’s modulus and stress at 3% strain with mass fraction is greater than the rate of decrease of ductility and toughness. This makes it possible to prepare composites with high modulus, stress at low strain and ultimate tensile strength as well as relatively high toughness and ductility. This could lead to new materials that are stiff, strong and tough.     

Sulfur-free lignins as composites of polypropylene films

To elucidate the effect of lignin addition, polypropylene films containing 2–10 wt % of spruce organosolv lignin and/or beech wood prehydrolysis lignin were compared with lignin-free polymers with respect to tensile strength and elongation before and after aging. The physicochemical properties of the lignin-containing films were investigated by conductivity measurements, surface behavior, and UV and IR spectroscopy. © 1993 John Wiley & Sons, Inc.     

聚硅氧烷改性水性聚氨酯的合成及其表面性能

以聚氧化丙烯二醇(PPG)、双羟基亲水性聚硅氧烷多元醇(UC3667)为软段,异佛尔酮二异氰酸酯(IPDI)、1,4-丁二醇(BDO)、二羟甲基丙酸(DMPA)、乙二胺(EDA)为硬段,制备了一系列聚硅氧烷改性水性聚氨酯(WPUs)。用DLS和FTIR表征了水性聚氨酯乳液粒径和膜结构。通过热重分析、拉伸测试、接触角测试、XPS对水性聚氨酯胶膜的性能进了测定。结果表明:随着聚硅氧烷加入量的增多,水性聚氨酯膜拉伸强度先增大后减小;且聚硅氧烷的加入提高了水性聚氨酯膜的热稳定性、断裂伸长率、接触角,降低了水性聚氨酯膜的表面能。当聚硅氧烷质量分数为5.0%时,胶膜表面的硅迁移量达到饱和,表面能为27.27 mJ/m~2。     

葡萄糖改性水性聚氨酯的合成与表征

采用预聚体合成法,以二羟甲基丙酸（DMPA）、葡萄糖（PG）为亲水扩连剂和交联剂制备一种水性聚氨酯乳液。利用FTIR对胶膜结构进行表征,证实葡萄糖已引入聚氨酯主链。TG分析得出PG改性后的聚氨酯胶膜热稳定性增强。研究了PG用量对该聚氨酯胶膜力学性能的影响,结果表明：随着PG用量的增加,胶膜力学强度得到改善。当PG的用量由0增加至4.68%时,断裂伸长率从529.9%降至276.4%,拉伸强度从10.9 MPa增加至24.2 MPa。     

Synthesis of polyurethanes from solvolysis lignin using a polymerization catalyst: Mechanical and thermal properties

Two methods of synthesis, namely, using a polymerization catalyst versus a non-catalytic route, were investigated to produce lignin-based polyurethanes. The films were characterized with respect to crosslink density, ultimate tensile behavior and glass transition temperature. The results indicated that use of the catalyst for polymerization is an effective way for producing films with consistent properties, even at lignin contents as high as 45 to 50 wt%. To illustrate the catalyst effectiveness, crosslink densities of catalyzed films with 20 wt% of lignin content increased drastically from 0.2-0.3 to 1.7-2.7 mmol/cm 3 when the NCO/OH molar ratio increased from about 1.3 to 3.0, without much increase in the corresponding crosslink densities of the non-catalyzed films. Also, when the NCO/OH molar ratio increased from 1.2 to 3.2, the tensile strength increased from 1.9 MPa to a maximum of 55 MPa (NCO/OH=2.6) before decreasing. Also, for same NCO/OH ratios, ultimate strain decreased drastically from 174.4% to 4.3%, with a corresponding increase in Young's Modulus from 0.03 GPa to 2.8 GPa. The glass transition temperatures of the catalyzed films also increased from 35°C to 89°C. Without the catalyst, only polyurethanes with low NCO/OH ratios, low lignin contents, and inferior mechanical properties, could be synthesized.