含羰基端羟基硅氧烷改性聚氨酯弹性体的结构及性能

以聚四氢呋喃醚二醇(PTMG)和含羰基的端羟基硅氧烷(PDMS-C)为混合软段,采用预聚体法合成了一系列PDMS-C改性聚氨酯弹性体(SPUs),用傅里叶变换红外光谱对其结构进行了表征,并考察了PTMG与PDMS-C的摩尔比对SPUs力学性能和耐高低温性能的影响。结果表明,PDMS-C成功接枝到聚氨酯链段中。随着PDMS-C含量的增大,SPUs的拉伸强度降低,但与普通端羟基硅氧烷改性聚氨酯相比,其拉伸强度保持率大幅提高;随着PDMS-C含量的增大,SPUs的耐高低温性能均得到改善。     

炭黑对高阻尼天然橡胶/溴化丁基橡胶并用胶性能的影响

研究不同种类炭黑对高阻尼天然橡胶/溴化丁基橡胶(NR/BIIR)并用胶性能的影响。结果表明:炭黑用量相同时,炭黑结构度越高、粒径越小,胶料物理性能越优;炭黑N774填充胶料的阻尼性能最优;对于相同硬度的高阻尼NR/BIIR并用胶,炭黑N110填充胶料的常温阻尼性能最优。     

改性炭黑增强三元乙丙橡胶的力学性能与加工性能

研究了用甲基丙烯酸缩水甘油酯(GMA)、甲基丙烯酸-2-羟乙酯(HEMA)和N-羟甲基丙烯酰胺(NMA)3种单体改性炭黑增强三元乙丙橡胶(EPDM)的力学性能,并用橡胶加工分析仪分析了GMA、HEMA和NMA改性炭黑对EPDM未硫化胶的加工性能。结果表明,GMA、HEMA和NMA改性炭黑均改善了EPDM硫化胶的力学性能,当其用量分别为3.75,3,3份时,EPDM硫化胶的定伸应力、拉伸强度和撕裂强度达到最佳值;降低频率、提高应变或温度有利于改善改性炭黑增强EPDM的加工性能。     

双螺杆挤出长玻纤增强复合材料玻纤含量快速调试方法

通过试验和理论分析提出了双螺杆挤出长玻纤增强复合材料过程中两种准确控制玻纤含量的方法,这些方法可以快速调节长玻纤增强复合材料生产时的玻纤含量,降低机头料的废品率及提高设备的利用率,同时可以迅速更正因原材料更换批次所引起的玻纤含量的波动,能为现场指导长玻纤增强复合材料生产、稳定产品质量提供快捷而有效的支持。     

Microstructure and mechanical properties of Al−Mg−Si alloy U-shaped profile

To get a full understanding of hot extrusion, solid solution treatment and aging process on the Al−0.56Mg− 0.63Si alloy, the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy, scanning electrical microscopy, transmission electrical microscopy, hardness, and tensile tests. The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion. The fibrous deformed and sub-structured grains located between the two coarse grain layers, due to the occurrence of work-hardening and dynamic recovery. Perpendicular needle β′′ precipitates were distributed inside the grain, and obvious precipitates-free zone appeared after aging treatment. The tensile strength, yield strength and elongation of the aged Al−Mg−Si alloy U-shaped profile were no less than 279.4 MPa, 258.6 MPa, and 21.6%, respectively. The fracture morphology showed dimple rupture characteristics. The precipitates and grain boundaries played key role in the strengthening contribution.     

聚苯乙烯泡沫作为风电叶片夹芯材料的可行性研究

讨论了聚苯乙烯(PS)泡沫在风电叶片中的应用,通过对比研究聚氯乙烯(PVC)泡沫和PS泡沫本体以及泡沫玻璃钢夹芯结构的力学性能,通过有限元模拟夹芯结构悬臂梁在加载后发生的位移值来判断PS泡沫作为夹芯结构的芯材对整体刚度的影响,并通过实验测量和有限元模拟泡沫夹芯结构。结果显示,PS泡沫本体力学性能较PVC低;PS泡沫作为夹芯结构的芯材可以使用在叶片的剪切腹板中,在替代PVC泡沫使用在壳体蒙皮的夹芯层中,若要保证蒙皮的刚度不变则需要增加PS泡沫的厚度。     

Modification In Situ of EPDM Filled with Carbon Black by Glycidyl Methacrylate

A method of chemical modification in situ of ethylene-propylene-diene rubber (EPDM) filled with carbon black was studied. A bifunctional monomer, glycidyl methacrylate (GMA), was used as the modifier to improve the dispersibility of carbon black in the rubber and to enhance the mechanical properties of EPDM vulcanizates. The effects of GMA on the structure and properties of EPDM vulcanizates such as determination of cross-linking density and vulcanizing properties as well as mechanical properties were investigated by FT-IR, SEM, and DMTA. The results showed the addition of GMA into carbon black filled EPDM compounds could remarkably improve the mechanical properties of the vulcanizates. The optimum content of GMA was about 5.0 phr when the content of carbon black was 50 phr. The reason for improvement of the mechanical properties might be attributed to the chemical combinations between rubber macromolecular chains and carbon black surfaces by GMA. The action of GMA was similar to a cocuring agent and a coupling agent.     

风电叶片用环氧树脂和不饱和聚酯性能的对比研究

对比了环氧树脂和不饱和聚酯的各项性能,通过对树脂的黏度-时间曲线测试,结果显示不饱聚酯在整个操作时间内黏度变化不大,具有优异的工艺调控性。结合扫描电子显微镜(SEM)对两种树脂断口形貌的观察和力学性能测试来研究两种树脂的区别,结果表明,虽然不饱和聚酯的弯曲强度和抗压强度较高,但是平均2.41%的断裂伸长率远低于环氧树脂的8.71%。由玻璃化转变温度(Tg)测试分析主要是不饱和聚酯内自由体积较低,在本体受到拉伸时无法通过分子内链段的运动来降低体系内拉应力,所以本体脆性增大,最终导致了材料在变形量较大时的使用受到限制。     

多指标正交实验优化可发性三聚氰胺甲醛树脂的制备

用己内酰胺作改性剂,通过正交实验设计考察了甲醛和三聚氰胺摩尔比(F/M)、溶液pH值、反应温度(T)和反应时间(t)对可发性三聚氰胺甲醛(MF)树脂的储存期、固含量、黏度、MF泡沫密度及泡孔尺寸均匀性的影响,运用综合评分法和综合平衡法对正交实验结果进行了分析,得出最优水平组合:F/M=2.5,pH=8.0,T=90℃,t=60min。最优条件下合成的MF树脂可发泡性良好,制得的泡沫性能优良。     

还原氧化石墨烯-SBA/PMMA复合材料的制备及介电性能

采用乳液聚合法制备苯乙烯-丙烯酸丁酯共聚物（SBA）,通过熔融共混法制备了还原氧化石墨烯/SBA-聚甲基丙烯酸甲酯（rGO-SBA/PMMA）复合材料,采用FTIR、TGA、动态力学分析对复合材料进行了结构表征,并对其进行了介电性能测试。结果显示,rGO的加入能够提高SBA的玻璃化转变温度。同时,也可以提高rGO-SBA复合材料的热稳定性。rGO的加入显著提高了rGO-SBA复合材料的介电常数。在rGO-SBA复合材料中,其渗流阈值在1.17wt%~2wt%之间,当rGO含量为1.17wt%时,rGO-SBA复合材料具有高的介电特性。在rGO-SBA/PMMA复合材料中,当SBA含量为13wt%及rGO含量为0.52wt%时,在频率为1 000 Hz处其介电常数可达到8.79,且介电损耗低至0.37,进一步表明了rGO-SBA/PMMA复合材料具有高介电低损耗的特性。