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21.
由电化学酒精传感器、温度传感器、压力传感器、87C552单片机、LCD显示屏和扬声器等部件构造酒精浓度测试仪。设计电路将电化学酒精传感器产生的微电流转换为0~5 V电压输出,以满足87C552内置电压模ADC的需要。通过测量电化学酒精传感器的环境温度,查询保存的电化学酒精传感器的信号比率与环境温度之间的关系数据,计算出准确的酒精浓度。解决了电化学酒精传感器酒精气体燃烧转变为电能输出转换率易受环境温度影响的问题。经过仿真测试性能稳定。 相似文献
22.
明胶/自交联苯丙聚合物的制备及其表面施胶性能 总被引:1,自引:0,他引:1
以N-羟甲基丙烯酰胺(NMA)作自交联单体,明胶(Gel)为高分子分散稳定剂,苯乙烯(St)和丙烯酸丁酯(BA)为单体,采用无皂种子乳液聚合制备了稳定的自交联苯丙乳液,并优化了合成工艺条件。研究表明:当w(Gel)=32%,软硬单体比例n(BA)/n(St)=2∶1,w(NMA)=4%时,自交联苯丙乳液具有优异的施胶效果,当以质量分数为1%的聚合物乳液进行表面施胶时,纸张施胶度可达52.0 s,环压指数达5.9 N/m/g,耐折度13次;环压指数和耐折度分别比空白样提高了23%和62.5%。 相似文献
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With the assistance of polymerisable maleate surfactant and costabilizer, core–shell emulsions with poly(butyl acrylate) core (PBA) and poly(butyl acrylate–styrene–methacryloxypropyl trimethoxysilane) shell (PSBM) were prepared through seeded emulsion polymerization. Effects of MPTS on rheological, mechanical, and thermal properties were investigated. Simultaneously, the emulsions were utilized as paper surface sizing agents, and corresponding properties were studied. It was found that the emulsion possessed viscoelastistic nature and changed from viscous to elastic with MPTS addition. At the same time, enhanced internal network strength among particles was detected, which was weakened when MPTS concentration was 8%. The tensile strength and thermal stability of copolymer films were therefore increased accordingly. However, decrease in tensile strength, elongation at break and thermal properties was observed with higher MPTS concentration due to weakened interaction among different shells. It was also found that glass transition temperature (T g) did not influence greatly by MPTS, and two phases corresponding to core and shell copolymer were observed with low degree of microphase separation. Furthermore, the interaction between polymer and fiber was improved, resulting in improved sizing degree, ring crush strength, surface strength, and folding strength. While the surface strength and folding endurance decreased due to the increase of brittleness with higher crosslinking degree. 相似文献
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Chunyan Wang Xiaorui Li Jingqian Chen Guiqiang Fei Haihua Wang Qin Liu 《应用聚合物科学杂志》2011,122(4):2630-2638
A graft copolymer was synthesized by graft copolymerization of starch with styrene (St) and butyl acrylate (BA), using ferrous sulfate‐hydrogen peroxide redox initiation system. The starch was pregelled in the presence of acrylonitrile (AN) in aqueous alkali at high temperature before graft polymerization. Major factors affecting the polymerization reaction were investigated. It was found that a graft copolymer with higher percentage conversion (PC), graft efficiency (GE) and graft percentage (GP) was obtained by controlling the initiator concentration, concentration, and ratio of monomers and polymerization temperature. The optimum conditions were as follows: H2O2 concentration, 12%; monomer concentration, 120%; St/BA ratio, 1 : 1; polymerization temperature, 65°C. Fourier transform infrared spectroscopy and NMR analyses were used to gain information on the structure of the products. It was demonstrated that St, BA, and AN had been successfully grafted onto starch and ? CN had been saponified into ? CONH2 and ? COO? to a certain degree when pregelling. Scanning electron microscope micrographs showed the coarse structure and broad network. The graft polymerization took place on the surface of starch granule and led to amorphization of the starch structure. Graft polymer had better thermal stability and was endowed with pseudo‐plasticity. It was observed that the starch graft copolymer offers good properties such as water resistance as surface‐sizing agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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A zinc‐based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including L ‐lactide (L ‐LA) and 2‐methyl‐2‐carboxyl‐propylene carbonate (MBC). The polymerization of L ‐lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [M]0 /[I] (molar ratio of monomer to initiator). Sequential polymerization of L ‐LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the L ‐LA bulk polymerization with a high monomer conversion. 13C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the D ‐LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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通过1个水泥土模型桩和2个劲性水泥土组合模型桩以及2个加筋劲性水泥土组合模型桩的静载荷试验,分析了组合桩的极限承载力、Q-S曲线及应力-应变曲线.分析表明:1土工格栅围箍面积越大,模型桩的应力应变变化速度越缓慢;2围箍面积越大,提高承载力的作用越明显;3加筋劲性水泥土组合桩的4根芯桩离桩心距离为40mm时,土工格栅的作用最明显,其极限承载力提高12.5%. 相似文献
29.
Xiahong Zhang Jianwen Yang Zhaohua Zeng Yuanwei Wu Liang Huang Yonglie Chen Haihua Wang 《Polymer Engineering and Science》2007,47(7):1082-1090
A series of acrylic oligomer which can undergo self-initiation under UV irradiation were synthesized by Michael addition of acetylacetone (acac) with multi-functional acrylates using diazabicycloundecene as catalyst. GC-MS and proton NMR were employed to study the photolysis mechanism of model molecule which was prepared from acac and ethyl acrylate. The β-diketone moiety attached to a fully substituted carbon atom was photoscissile and prone to produce alkyl free radicals by losing acetyl free radical. Polymerization of the acrylated β-diketone-containing oligomers can be thus efficiently triggered regardless of solely irradiated under UV light or blended with pure trimethylolpropane triacrylate. As determined with photo-DSC, the acrylated β-diketone-containing oligomers photopolymerized more slowly than the traditional system of trimethylolpropane triacrylate containing Darocur 1173 at the early stage, but reached a higher final conversion. The rheology measurement showed that the synthesized acrylated β-diketone-containing oligomers exhibited shear thinning property. POLYM. ENG. SCI., 47:1082–1090, 2007. © 2007 Society of Plastics Engineers 相似文献
30.
本文针对使用误差级数时存在的问题给出了误差级数使用条件,得到了误差级数使用条件与闭环传递函数极点和输入信号频率之间的直接关系。所得结论有益于分析实际系统的稳态误差。 相似文献