为了研究氯水老化pH值对氨纶的影响,使用不同pH值的次氯酸钠溶液对氨纶进行老化处理,随后采用傅里叶变换红外光谱、X射线衍射、差示扫描量热及力学性能测试分析老化后样品的氢键化程度、微相分离程度、结晶性、热性能与拉伸性能.结果 表明:氨纶氢键化程度、微相分离程度和硬段结晶度都随氨水pH值的降低而减弱.在热性能方面,随着氯水pH值的降低,氨纶的玻璃化转变温度与软段结晶熔融温度升高,软段结晶度减小.在拉伸力学性能方面,低pH值氯水处理后的氨纶表现出更小的断裂强力和断裂绅长率.

Abstract This paper presents an experimental study about the effects of UV irradiation on polyether polyurethane (PU) fibers investigated by FTIR, SAXS and AFM, and the multiple mechanism is finally proposed.The results show that, at low UV irradiation (0.6W/m2, 0.9W/m2), the mechanism responsible for UV degradation of polyether PU fibers could be described as a primary reaction causing the break up of chemical bonds and forming the new quinone structure, along with a secondary reaction to explain hydrogen peroxide formed in the presence of UV irradiation, water and oxygen environment which promotes QUV aging by providing loose structure of polyether PU fibers. Moreover, the micro phase separation is promoted for a parallel reaction occurred to produce new polyether PUs and more compact micro domains by the residual isocyanate in pre-polymerization stage and alcohols formed under QUV aging. Under higher UV irradiation (1.2W/m2, 1.5W/m2), in addition to the primary reaction, a tertiary reaction showing the re-polymerization occurred under accumulation of aging products (carboxylic acids and alcohols) is also considered as the mechanism, while the secondary reaction would be inhibited for the peak assigned to H2O2 is not observed. Also, this decreases micro phase separation of polyether PU fibers for the primary reaction is dominant.

ABSTRACTThe dynamic viscoelasticity of polyurethane fiber (PUF) under small strain was studied with dynamic mechanical analysis and differential scanning calorimetry, and its viscoelasticity was predicted in a wide frequency range. The results revealed that the loss factor (tan δ) was about 0.05 and the phase angle (δ) was 2.86°, very close to the δ of a perfect elastomer in the range from −100°C to −80°C. The master curves superimposed by time‐temperature superposition (TTS), the frequency range of the storage modulus master curve spanned 17 orders of magnitude from 10−7 Hz to 1010 Hz, and the loss modulus master curve spanned 13 orders of magnitude from 10−3 Hz to 1010 Hz. The apparent activation energy of the soft segment relaxation decreased with increasing temperature in the range from −70 to −26°C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47070.

Polyurethane fiber (PUF) can be used as self-adaptive material in the field of nuclear physics and its properties depended on the molecular structure. To explore the effect of side methyl on its degree of microphase separation (DPS) and morphology for PUF, ethanediamine and 1,2-propylene diamine with different molar ratio were used as mixed diamine chain extenders (MDCEs) to fabricate PUF. The effect of side methyl content on the H-bond, crystallinity, DPS and mechanical performance were investigated with FTIR, XRD, AFM, SAXS, universal tensile machine (UTM) and DMA, respectively. The results of FTIR and XRD revealed that the hydrogen bonds (H-bonds) and crystallinity increased with the decrease of side methyl content on account of the reduction effect of steric hindrance. Furthermore, due to the stronger H-bonds and higher crystallinity in hard segment domain (HD), the DPS of PUF was enhanced with the increasing molar ratio of MDCEs in the aspect of the ordered structure in soft segment domain and the enlarged HD. Therefore, PUF showed more excellent mechanical performances with the improved DPS. The elongation at break extended from 482% to 557%. Static stress relaxation rate V increased while static stress relaxation ratio R decreased. Furthermore, T-g,T-s of soft segment moved to the low temperature direction. These results demonstrated how the microstructure-to-properties of PUF could be influenced by side methyl from MDCEs.

In this study, the effect of small strain ( less than 10% ) on hydrogen bond ( H-bond ) and crystallinity of dry-spun polyurethane fi ber was investigated with fourier transform infrared spectroscopy and x-ray diffractometer, respectively. The results showed that the H-bond of hard segments hardly broke and its degree of crystallinity scarcely varied below strain of 10%. The fi ber stress relaxation behavior at 25 ° C under small strain was researched using dynamic mechanical analyzer. The stress relaxation modulus constitutive equation was obtained by transforming the non-linear relationship between stress and time into the linear relationship between stress and strain. The stress relaxation modulus master curve at 25 ° C was established in terms of short-term stress relaxation tests at elevated temperatures ( 35 ° C, 45 ° C, 65 ° C and 75 ° C ) according to time-temperature superposition principle ( TTS ) to predict long-term behavior within 353 year.

以2,5– 呋喃二甲酸(FDCA)、对苯二甲酸(PTA)、乙二醇(EG)为原料,钛酸四丁酯为催化剂,通过改变FDCA与PTA物质的量之比,采用原位聚合法来制备聚2,5– 呋喃二甲酸 – 对苯二甲酸乙二酯(PEFT),并对其结构和性能进行了分析表征.通过傅里叶变换红外光谱、核磁共振氢谱测试对不同配比PEFT共聚酯的结构进行分析,可以清晰地分辨出特征官能团的标志峰;通过热重分析、差示扫描量热测试对PEFT的热性能进行分析.研究发现随着FDCA含量的增加,其玻璃化转变温度先降低后升高;当FDCA含量超过10％ 之后,PEFT聚酯没有冷结晶温度及熔点.经过对抗静电性能测试,共聚酯的表面电阻率由1014Ω 降低至109Ω 数量级,并具有良好的抗静电功能耐久性和耐热性.

Nowadays, halogen-free high flame retardance of rigid polyurethane (RPU) foam without deteriorating its intrinsic performances is still a great challenge. Here, a green surface flame-retardant (SFR) strategy of RPU foam was proposed. In detail, a new halogen-free UV-curable self-extinguished coating was developed and then combined onto the surface of RPU, obtaining a surface flame-retardant RPU foam system (SFR-RPU). The SFR-RPU foams exhibit highly-efficient flame retardancy at a coating thickness of 25 mu m, showing a fast self-extinguishing behavior. A compact porous char layer served as a good barrier can be rapidly formed on the surface of SFR-RPU. The detailed flame-retardant mechanism was proposed. Furthermore, when compared to neat RPU, the compressive strength of SFR-RPU foams is enhanced and the heat-insulation property is maintained perfectly. This facile, low-cost and environmental-friendly post-treatment of RPU foam could expand its fire safe commercial applications.

根据Hooke弹簧和Newton粘壶,提出一种由Maxwell元件和粘滞系数随应变增大的粘壶并联组成的模型,对氨纶的拉伸过程进行模拟.首先,将乙二胺和1,2-丙二胺按物质的量之比3.4:1,4.5:1,6.3:1,10:1和21:1配制扩链剂,制备5种扩链剂配比的氨纶;然后对不同扩链剂配比的氨纶进行拉伸测试并对其拉伸曲线进行拟合,分析模型参数;最后对5种扩链剂配比的氨纶进行傅里叶变换红外光谱测试,结合氨纶的氢键化程度分析模型参数随扩链剂配比的变化规律.结果表明,该模型能较好地拟合氨纶的拉伸曲线,5种扩链剂配比的氨纶拉伸曲线拟合度均大于0.999;模型的弹性模量与粘滞系数随扩链剂配比的增大而增大,与氨纶氢键化程度的变化规律一致,扩链剂配比增大使氨纶抵抗变形的能力增强,在模型上则体现为弹性模量与粘滞系数的增大.

为了考察氨纶在不同温度下的紫外老化特性,采用了红外光谱、热重分析仪和万能试验机对老化后纤维的外观形貌、微观结构和力学性能进行了测试表征.结果表明,相对于软链段,老化温度对硬链段的影响更加显著.随着老化温度的增加,氨纶热稳定性不断降低,氢键化程度也随之下降,断裂伸长率不断增加,400％应变模量不断降低,且内耗逐渐升高.在老化过程中伴随着交联反应,氨纶颜色随温度的增加依次加深.该研究结果可为氨纶的生产使用提供依据.

To study the influence factors of the explosion accident caused by the abnormal increase of pressure in the chemi -cal reaction tank , the influence factors were found out and sorted according to the structural importance based on the fault tree safety analysis method .Among which , the temperature monitoring without feedback in time , the poor agitation effect and the incompletely cleaning of tank were the top three reasons .The structure of chemical reaction tank was optimized based on the results of fault tree safety analysis .It showed that embedding the thermometer at the bottom of the tank ' s internal wall and connecting it to the temperature indicator with the wires , and fixing the temperature indicator on the side wall of jacket are convenient for carrying out the real-time monitoring of temperature .Installing the cleaning device on the top cover of tank to clean the tank after use is convenient for improving the cleansing efficiency .Improving the agitation effect of the agitation device on the materials inside the tank is convenient for the efficient reaction of the materials and the timely heat dissipation , so as to reduce the occurrence of safety accidents .

In this study, the effect of small strain (less than 10%) on hydrogen bond (H-bond) and crystallinity of dry-spun polyurethane fiber was investigated with fourier transform infrared spectroscopy and x-ray diffractometer, respectively. The results showed that the H-bond of hard segments hardly broke and its degree of crystallinity scarcely varied below strain of 10%. The fiber stress relaxation behavior at 25 degrees C under small strain was researched using dynamic mechanical analyzer. The stress relaxation modulus constitutive equation was obtained by transforming the non-linear relationship between stress and time into the linear relationship between stress and strain. The stress relaxation modulus master curve at 25 degrees C was established in terms of short-term stress relaxation tests at elevated temperatures (35 degrees C, 45 degrees C, 65 degrees C and 75 degrees C) according to time-temperature superposition principle (TTS) to predict long-term behavior within 353 year.

Dicalcium phosphate was prepared by ethylenediaminetetraacetic acid as a calcium chelating agent, and further explored to remove the fluoride ions from aqueous solution. The as-prepared samples main existed in the monetite phase from the result of XRD. The dried sample consisted of small nanoparticles and displayed irregular particles with a size of ca. 3??m due to the agglomeration. The fluoride removal ability was evaluated by batch adsorption experiments. The as-prepared adsorbent exhibited the enhanced fluoride removal behaviour with the maximum adsorption capacity of 66.72?mg/g from the Langmuir isotherm model, which was higher than that of other previously reported calcium phosphate. The adsorbent could be utilized in the wide pH range of 3?10. The adsorption kinetics could be better described by the pseudo-second-order model than first-second-order model. The co-existing anions had a negligible influence on the fluoride adsorption. The investigation of adsorption mechanism suggested that the chemical reaction and/or dissolution ? precipitation mechanism should be dominant in the fluoride adsorption process, accompanying with electronic interaction and ions exchange, which enhanced the fluoride removal performance.

In thiswork, dynamic thermodynamic analyzer (DMA) was used to determine the stress-temperature relationship of polyurethane fibers to research the thermodynamic properties under small strains. The results show that the stress of polyurethane fibers increases with the increase of temperature. The study of the energy conversion during the heating processof polyurethane fibers demonstrates that the entropy change decreases with the increase of the strain while the enthalpy change has the contrary tendency. The entropy change is the key reason for the stress of polyurethane fibers.

某企业工件表面防腐蚀涂层尚未出厂就开始脱落,为分析失效原因,对使用后的溶剂、固化剂、环氧树脂进行红外光谱检测,发现原材料无误.通过进行涂层失效分析,发现失效涂料中环氧树脂与固化剂的特征峰的调配比例为1.3∶1.0,远远偏离6.0∶1.0的正常比例.因此,失效原因为环氧树脂与固化剂的调配比例不当.

Aging experiments of spandex was carried out under different condions in QUV aging machine,while the influence of UV aging time on structure and properties of spandex under high temperature and high humidity was obtained with analysis of Fourier transform infrared spectroscopy (FTIR),differential scanning calorimeter,X-ray diffraction and mechanical tests. The results show that with the increase of aging time,the hydrogen bonding degree of N—H groups became larger and C—N bonds broke down while the methyl dehydrogenation converted to methylene. Thermal properties of spandex declined continuously,while Tgincrease and the microphase separation degree become worse. Crystallization degree of spandex has little change during early period,which increase until 150 h and then decrease. The elongation at break and breaking strength of UV-aged spandex decrease significantly at the beginning of aging (0-50 h) and then slowly increase at 200 h and 150 h respectively. The elastic modulus show similarly trend with crystallinity degree of spandex,which increase until 100 h and then decrease,while the rate of 300% elastic recovery decrease continuously. Furthermore,ether group show no significant change at 1 110 cm-1while the C=O peak caused by water is emerged at 1 710 cm-1and the N—H peak is weaker at 3 317 cm-1due to breakup of C—N from aged and unaged FTIR,which show UV and water dominate during the aging period while aging progress can be accelerated under experiment temperature.

In this study, a two-element model consisting of a non-linear spring and a viscous dashpot was proposed to simulate tensile curve of polyurethane fibers. The results showed that the two-element model can simulate the tensile curve of the polyurethane fibers better with a simple and applicable feature compared to the existing three-element model and four-element model. The effects of isocyanate index (R) on the hydrogen bond (H-bond) and the micro-phase separation of polyurethane fibers were investigated by Fourier transform infrared spectroscopy and x-ray pyrometer, respectively. The degree of H-bond and micro-phase separation increased first and then decreased as the R value increased, and gain a maximum at the value of 1.76, which is in good agreement with parameters viscosity coefficient eta and the initial modulus c in the model.

The creep behaviors of self-adaptive fiber spandex were researched. Firstly,polyethylene tetrahydrofuran ether glycol and 4,4′-diphenylmethane diisocyanate were reacted to form the prepolymer at the molar ratio of 1.0:1.6,the prepolymer solution with concentration of 35%was got by adding solvent N,N-dimethyl acetamide,then spinning dope was made by using eth-ylenediamine extender to conduct chain reaction,spinning dope spew from the spinneret plate was dried in the hot bust,where air volume was 690 m3/h and the temperature was 244℃,then a sample of dry spinning spandex with the density of 11.67 tex with the spinning draft ratio of 1.00:1.10. The strain of spandex at different time was tested under the actual condition of application of the self-adaptive fiber (25℃ and small-stress). Then the two kinds of generalized Kelvin model,fractional exponential model and Findley power law model were used to fit the experiment data. The results show that Fractional exponential model can well reflect the variation of strain of spandex with different stresses and different time,and the mathematical expression of the tensile creep mod-el of spandex was established. The maximum relative error between the strain calculated values by the expression at different time and different stress and the corresponding measured values is 5%. Therefore the expression can predict the creep behavior of spandex material better.

The prepolymer was obtained by the reaction of MDI and PTMG with different molecular weights (1400,1800, 2200,2600,3000),34.5% prepolymer solution was prepared with DMAc as solvent,and then spinning solution was prepared by expanding chain with EDA/PDA mixture. Then 5 kinds of spandex samples were obtained by dry spinning,the degree of hydrogen bonding of these samples was measured by Fourier transform infrared spectrometer. The influence of molecular weight of soft segment on the microphase separation of spandex was also studied by using small angle X ray system and dynamic mechanical analyzer. Finally,the universal material testing machine was selected to test its tensile properties. The results show that with the increase of molecular weight of soft segment,the content of hard segment decrease. Furthermore,the degree of hydrogen bonding, microphase separation and fracture strength of polyurethane all increase until molecular weights 2200 and then decrease. The elongation at break decrease until molecular weights 2200 and then increase with increasing molecular weight of soft segment.

The disperse blue 56 dye was selected to dye polyether polyurethane,and the color fastness grade and surface color depth were determined,according to methods of Fourier transform infrared spectroscopy ( FTIR),X-ray diffraction and mechanical property test study from the micro perspective and analyze the dispersion of different process parameters of dye dyeing polyurethane (time,temperature and pH of dye solution) effects on its structure and properties. In order to put forward the optimum conditions for polyurethane dyeing. The results show that color fastness is not enough and decoloring when the dyeing temperature less than 120℃, surface color value (K/S value) and breaking strength substantial decline when the dyeing temperature more than 130℃,and poly-urethane damage seriously,the dyeing temperature shall be controlled at 120-130℃ interval. The best dyeing time is 30 min,short dyeing time causes the dye molecules and polyurethane binding difference but more than 30 min will cause the degree of hydrogen bonding decreases,the crystallinity decreases to reduce the tensile strength,and dyeing performance. When dye liquor's pH value is 5-6,polyurethane has good acid resistance,poor alkali resistance,good dyeing performance and mechanical properties of polyure-thane with less damage under weak acid condition.

The effects of different spinning dope concentrations on the stress relaxation of spandex were studied by using dry spinning technique.The stress relaxation rate was calculated by choosing the appropriate spinning solution concentration.The stress relaxation rate and the stress relaxation speed rate of the five kinds of spandex were calculated and analyzed.The results show that the stress relaxation rate and the stress relaxation speed rate of spandex decrease with the increase of the concentration of the spinning solution.The five-element generalized Maxwell model was used to explain the stress relaxation behavior of spandex,and the five parameters of the five-element model were obtained by fitting the actual stress relaxation curve of spandex.By analyzing the concentration of spinning liquid and the coefficient of spring decay elasticity,the relationship can be well described in the first two stages of the five kinds of spandex stress relaxation processes.