光屏蔽剂对聚甲醛老化过程结构与性能的影响

采用炭黑和氧化锌两种光屏蔽剂对共聚甲醛进行耐老化改性。研究了改性前后聚甲醛在紫外光老化及热氧老化过程中的表面层及内部发生的微观物理化学变化,包括熔点、结晶度、表面羰基量及分子量变化等。结果表明,紫外光的照射主要导致聚甲醛试样表面层发生晶体破坏和无定形部分分子链降解,内层则主要发生非晶区重整结晶;热氧作用下聚甲醛发生氧化降解的同时整体较均匀地发生非晶区重整结晶,以上情况均导致聚甲醛结晶度上升、拉伸强度提高,但抗冲击韧性及断裂伸长率显著下降,如经过1000 h紫外光辐照后,聚甲醛表面层结晶度由42.06% 上升至 76.27%,而简支梁缺口冲击强度由6.74 kJ/m2 迅速下降至1.85 kJ/m2。通过添加1.5%~3%的炭黑或氧化锌可以有效地抑制紫外光对聚甲醛的降解和重结晶过程,从而提高材料老化后的性能保持率,但炭黑对抗氧剂过强的吸附力导致聚甲醛的热氧稳定性下降。     

酸碱条件对聚苯硫醚纤维力学性能的影响

研究酸和碱对聚苯硫醚纤维性能的影响.通过场发射扫描电镜(FESEM)、单纤强力仪和差示扫描量热仪(DSC)对酸、碱处理前后PPS纤维的表面形貌、力学性能和热学性能进行研究.结果表明:NaOH和H2SO4对PPS纤维的性能影响较小;而HCl、HNO3对PPS纤维各种性能的影响较大.经HCl、HNO3处理后PPS纤维表面出现凹槽和裂痕,其断裂强力和断裂伸长率随HCl、HNO3浓度增大和处理时间的延长而降低;经酸碱处理后的PPS纤维的热焓值都有不同程度的下降,其中经HNO3处理后其热焓值降幅最大.     

高速列车用高强铝合金疲劳断口的特征

通过宏观拍照和扫描电镜对A7N01高强铝合金T型焊接接头的疲劳断口进行了研究,揭示了该铝合金疲劳裂纹萌生与扩展的特征.铝合金的疲劳断口可明显划分为疲劳裂纹源区、裂纹稳定扩展区和瞬断区3大区域.疲劳裂纹从T型焊接接头的焊趾处萌生并向接头中心线扩展,疲劳裂纹扩展区可以观察到疲劳破坏的一些典型特征,瞬断区的断口形貌与拉伸断裂相似,形成不平坦的粗糙表面.     

热处理对桑蚕丝结构和性能的影响

以市售桑蚕丝织物为研究对象,蚕丝样品分别在50、100、150和200℃条件下进行加速热老化,对老化丝织物样品进行了断裂强力和白度测定,利用电镜和XRD表征手段考察了热老化处理对样品结构和性能的影响.结果表明:热处理后,丝纤维的形貌完整性和结晶度随着热处理温度的增加以及处理时间的延长而下降,热老化处理严重时纤维表面出现裂隙,甚至断裂.由于热老化使纤维结构产生破坏和损伤,织物断裂强度下降.     

水泥混凝土地坪"起砂露石"的薄层修复砂浆研究

通过对多种配方修补砂浆的抗压强度、抗折强度、抗拉强度、粘结强度、折压比、拉压比、干缩变形性能、弹性模量、耐磨性能的对比研究，发现了施工性能、力学性能、变形性能、耐久性能完全能满足“起砂露石”的混凝土地坪修补要求的砂浆，避免了采用板块拆除重浇、环氧砂浆罩面等修补方式所造成的费工耗时、色差严重、变形不同步或老化而导致粘结失效等问题。     

玻璃纤维混凝土在工程中的应用

田集电厂立交桥箱顶采用C30玻璃纤维混凝土抹成排水坡,箱顶面采用玻璃纤维混凝土.目的是利用玻璃纤维混凝土比普通混凝土抗拉、抗弯、抗裂强度高,其韧性、抗冲击性能比普通混凝土有较显著提高的特点.     

灾后重建用板房夹层泡沫聚苯乙烯的回收与改性研究

在四川“5•12”抗震救灾期间,地震灾区共建设板房62.5万套,其中成都有19万多套。按照灾后恢复重建和城市建设规划,数十万套活动板房将逐步拆除或回收利用,而如何回收利用板房泡夹层泡沫聚苯乙烯是一个重要的研究课题。本文以苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）作为增容剂,通过乙烯-辛烯共聚物（POE）和不同分子量的高密度聚乙烯（HDPE）来协同增韧回收废旧聚苯乙烯（rPS）。通过rPS/POE/HDPE/SBS四元体系制得的废旧PS复合材料的冲击强度为12.6 kJ/m2,拉伸强度为25.2 MPa,可以替代高抗冲聚苯乙烯（HIPS）使用,具有很好的经济效益和环境效益。而添加复配抗老化配方后,复合材料的抗紫外老化和抗热氧老化性能均得到提高,大大延长了复合材料的使用寿命。     

Effect of Pd ions in the chemical etching solution

The acrylonitrile-butadiene-styrene （ABS） surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized by atomic force microscopy （AFM） and X-ray photoelectron spectroscopy （XPS）. The results showed that with the increase of Pd concentration in the etching solution the ABS surface roughness reduced. The ratio of O to C increases and forms a large amount of O=C？O functional groups by dipping into Pd contained etching solution, thus the amount of colloids palladium adsorption increases. The carboxyl group acts as the ad- sorption site for the Pd/Sn catalyst.     

Chemical and thermal resistance of basalt fiber in inclement environments

To study the applicability of the basalt fiber through various experimental works in thermal and chemical environments, glass fiber and carbon fiber were compared and discussed. The tensile strength testing was used to investigate the corrosive resistance of basalt fiber, meanwhile, surface study by scanning electron microscopy and microanalysis with complementary X-ray diffraction analysis (SEM/EDS) was also used to ascertain the durability of basalt fiber. The basalt fiber showed better strength retention than the glass fiber at relatively high temperature. Its tensile strength increased when exposed at 300 °C for several hours, and still maintain about 70% of the initial strength at 400 °C, whereas that of the glass fiber decreased dramatically. The better stability of the basalt fiber was observed in hydrothermal and chemical environment. The tensile strength of the basalt fiber increased by 20% after the immersion in boiling water and remained well in acid solution, when it comes to glass fiber, the tensile strength decreased to some extent. Although the alkali resistance of basalt fiber was poor at the initial stage, it shows better resistance than the glass fiber after long time treatment.     

Ageing behavior of an Al-Zn-Mg-Cu alloy pre-stretched thick plate

The ageing behavior of a pre-stretched thick plate of Al-Zn-Mg-Cu alloy was systemically studied including one-step ageing, two-step ageing, and retrogression and reageing treatment (RRA). One-step ageing of the alloy resulted in peak ultimate tensile strengths of 595 and 575 MPa after 22 and 6 h at 120 and 135°C, respectively. The strengthening phase in peak aged (T6 temper) alloy contained GP zones and the η′ phase predominantly. After two-step ageing, the electrical conductivity was increased markedly, but the pre-stretched thick plate sacrificed a great loss of strength. RRA treatment provided a method for maintaining the strength close to that obtained by T6 temper and for obtaining the high electrical conductivity close to that obtained by T7 temper; the ultimate tensile strength and electrical conductivity were 583 MPa and 21.0 MS/m, respectively. TEM analysis of T7 and RRA specimens revealed two types of precipitates that contributed to age strengthening i.e. the η′ and η phases.     

Fabrication and characterization of anodic oxide films on a Ti-10V-2Fe-3Al titanium alloy

Anodic oxide films of the titanium alloy Ti-10V-2Fe-3Al in ammonium tartrate electrolyte without hydrofluoric acid or fluoride were fabricated. The morphology,components,and microstructure of the films were characterized by scanning electron mi-croscopy(SEM) ,X-ray photoelectron spectroscopy(XPS) ,X-ray diffraction(XRD) ,and Raman spectroscopy. The results showed that the films were thick,uniform,and nontransparent. Such films exhibited sedimentary morphology,with a thickness of about 3 μm,and the pore diam...     

一种高苯基含量有机硅阻燃聚碳酸酯的研究

以二苯基二甲氧基硅烷为单体合成出八苯基环四硅氧烷(P4),将其作为一种无卤硅系阻燃剂与聚碳酸酯(PC)按比例共混挤出制得无卤阻燃PC。对该无卤阻燃PC样品进行极限氧指数测试、UL-94垂直燃烧测试、扫描电镜(SEM)测试、热失重分析(TGA)、熔融指数(MI)测试和力学性能测试。实验结果表明,P4对PC具有显著的阻燃效果,随着P4用量增加,PC阻燃等级不断提高;P4均与分布在P4中,燃烧后炭层随着P4用量增大逐渐致密;该阻燃PC热稳定性有一定的提高,当P4添加量较高时空气氛围中热失重测试后残炭率显著提升;添加P4的阻燃PC熔指有所上升,分子量有所降低; 该阻燃PC拉伸强度和冲击强度在P4添加量较低时下降时较明显,当P4添加量达至4wt%后,拉伸强度和冲击强度变化很小,而该阻燃PC弯曲强度随着P4添加量增加变化很小。     

交联改性提高水性含氟丙烯酸树脂力学性能

丙烯酸树脂成本低、耐候性好、成膜性优异,被广泛应用于建筑、皮革化工等领域。但其表面能高,力学性能较差,使应用受到限制。为改善这一不足,以丙烯酸酯为主要单体,甲基丙烯酸十二氟庚酯为功能单体,三羟甲基丙烷三丙烯酸酯(TMPTA)为交联剂,采用核壳乳液聚合法合成了水性含氟丙烯酸酯树脂。对反应条件进行了考察,并对乳液的稳定性、粒径以及乳液膜的拉伸强度、硬度、疏水角、化学结构、热稳定性能进行了表征。结果表明,TMPTA的加入可以有效提高乳液膜的拉伸强度、硬度和热稳定性。TMPTA质量分数为2%时,乳液的平均粒径为157.2 nm,转化率为97.7%,乳液膜的综合性能最好。此时吸水率为12.3%,失重率50%时的分解温度为394 ℃,疏水角为98.9°,拉伸强度为3.5 MPa,硬度为71.2 HA,与含氟丙烯酸树脂相比拉伸强度提高了159.2%,热稳定性能提高了34.6 ℃。     

凯夫勒纤维的等离子体表面改性

采用了等离子体接枝和等离子体表面处理技术来改善凯夫勒纤锥的表面性质。X-射我光电子能谱、电子自旋共振谱、混性质和接触角的测试结果证明处理结果随时间延长并没有明显的老化效应。突验还表明,处理后的凯夫勒纤维抗张强度有所提高,用它制备的坏氧树脂复合材料层间剪切强度提高了60％以上。     

桑皮纤维／棉纤维混纺纱线拉伸性能的研究

为了研究桑皮纤维／棉纤维混纺纱线中桑皮纤维质量分数对混纺纱线拉伸性能的影响,纺制了不同混纺比的桑皮纤维／棉纤维混纺纱线,在YG061电子单纱强力仪上进行了拉伸性能测试,并对测试结果进行了分析和比较。结果表明,桑皮纤维／棉纤维混纺纱线的断裂强度随着桑皮纤维质量分数的增加而线性增加,当质量分数达到一定程度后,混纺纱断裂强度随着桑皮纤维质量分数的增加而降低。混纺纱线的断裂伸长率随着桑皮纤维质量分数的增加,有先增加后降低的趋势。总之,桑皮纤维质量分数在20％～30％范围内,混纺纱的拉伸性能比较优良。     

Mechanism of Surface Modification for Sericite

Surface modification of sericite by wet method was conducted with the addition of 1.0 % （w/w） silane. The resulting wetting contact angle and activity ratio of sericite were 130° and 98% respectively. Good pre-evaluation indexes of oil value （40.8%） and dispersivity （14.0 mL） were obtained. When 30 % of sericite was filled into acrylonitrile butadiene styrene（ABS） plastic, the bending strength and tensile strength of the composite material were reduced by 7% and 14.3% in comparison to those of pure ABS plastic, while the rigidity was increased by 3 times, and the impact strength and breaking elongation were reduced significantly. The mechanism of surface modification was investigated and the configuration of silane coupling agent on the surface of sericite was given. Infrared （IR） spectroscopic analysis indicates that the adsorption of silane on the surface of sericite belongs to chemical adsorption.     

棕榈叶鞘纤维的拉伸性能

研究了棕榈叶鞘纤维（棕榈纤维）在4种不同隔距和准静态条件下的拉伸力学行为,应用SEM观察并分析了纤维断裂面的结构,揭示了纤维断裂的机制.结果表明,棕榈纤维的力学指标具有分散性,强度和伸长率随拉伸隔距的增大而变小,而杨氏模量则呈相反趋势.由于棕榈纤维的结构特殊,强度和模量整体呈现随纤维直径增大而变小的特点.在拉伸过程中,微纤丝取向的改变导致了纤维应力应变曲线中的非线性部分变化,断裂面结构展现了受力时4个纤维细胞的变化过程,解释了纤维的断裂机制.     

竹炭纤维/棉混纺纱线拉伸性能研究

为了研究竹炭纤维/棉混纺纱中竹炭纤维含量与混纺纱拉伸性能的变化关系,对不同混纺比的竹炭纤维/棉混纺纱线在YG061电子单纱强力仪上进行拉伸性能测试,并对测试结果进行了分析和比较。结果表明:竹炭纤维/棉混纺纱的断裂强力随着竹炭纤维含量的增加先有逐渐减小的趋势,然后增大。竹炭纤维/棉混纺比小于临界混纺比时,混纺纱的断裂伸长率变化趋于平直;一旦超过临界混纺比,随着竹炭纤维含量的增加,断裂伸长率迅速增大。在实际应用中,混纺纱最低断裂强度对应的临界混纺比在设计中应尽量避免选用。     

聚酯热塑性弹性体热性能研究

选用晨光化工研究院牌号为H7563的聚酯热塑性弹性体(TPEE)进行热老化性能试验,比较热老化后拉伸强度的变化;采用扫描电镜观察热老化试验后表面的形貌;同时采用DSC定性分析了聚酯弹性体受热过程中发生的失水、失重、熔融和分解情况.试验结果表明,聚酯在高温下发生了链的断裂和键的破坏,从而发生了双分解反应,且在500℃的高温下几乎完全分解.     

酶处理对黄麻纤维性能的影响

选择含有纤维素酶、半纤维素酶、木质素酶和果胶解聚酶等成分的酶对黄麻纤维进行处理，并用偏光显微镜、荧光显微镜、扫描电子显微镜、万能电子强力机等仪器设备进行了测试分析．研究认为，酶处理对黄麻纤维的减量率影响较小．以纤维素酶为主要成分的Cellusoft L制剂对纤维强度影响最大，经24h处理后强度降低60％左右；主要分解木质素的Denilite制荆能够去除纤维表面的木质素，而对其他胶状物质不起作用；Viscozyme和Ultrazyme制剂能够去除纤维表面的胶状物质；经双氧水预处理后，Cellusoft L制剂和Cellnsoft UL制剂对纤维的作用效果大大增强．