Blends of polyamide (PA) 6 and phosphorous-containing hyperbranched polyamide (HBPA) were prepared by melt extrusion with PA6 as matrix and HBPA as modifier. The rheological behaviors,tensile and impact properties and flame resistance of the blends were investigated through capillary rheometer,mechanical properties tests,LOI test and TG analysis . The results show that with the content of HBPA increasing,the non-Newtonian index of the blend melt is close to 1 gradually and the melt tends to be converted to Newtonian fluids,the apparent viscosity decreases and it indicates that the processing property of the blend is improved,the viscous flow activation energy increases and it indicates that the temperature sensitivity of the blend is enhanced. Adding a small amount of HBPA can improve the mechanical properties of the blend,when the mass fraction of HBPA is 0.5%, the tensile strength is highest and increases from 62.6 MPa of pure PA6 to 72.4 MPa,when the mass fraction of HBPA is 1%,the elongation at break and notched impact strength is highest and increases from 228.3%of pure PA6 to 284.7%and from 19.8 kJ/m2 to 24.5 kJ/m2 respectively. The LOI test and TG analysis show that HBPA can improve the flame resistance of PA6 by promoting condensed phase charring,and when the mass fraction of HBPA is 1.5%,the value of LOI is highest and up to 28.4%.
采用熔融共混法制备了聚酰胺6/舍磷超支化聚酰胺(PA6/HBPA)共混物.通过差示扫描量热法(DSC)考察了该共混物的非等温结晶行为,并利用改进Avrami方程的Jeziorny法、Ozawa法和Mo法对DSC测试结果进行了非等温结晶动力学分析.结果表明:当HBPA用量为2％时,PA6基l体的结晶度和结晶速率均有所提高,而进一步增大HBPA用量则会对PA6的结晶产生阻碍作用,致使结晶速率降低.另外,Ozawa法不适于描述PA6/HBPA共混物的非等温结晶动力学,Jeziorny法则仅适用于PA6/HBPA的结晶初期和中期,而Mo法很好地描述了PA6/HBPA共混物的非等温结晶行为,因而可用于PA6/HBPA的非等温结晶动力学分析.
The effects of the functionalized multi-walled carbon nanotubes (MWCNT-P) on the curing behavior of a diglycidyl ether of bisphenol-A epoxy (DGEBA) in the presence of 4,4'-methylenedianiline were investigated by non-isothermal differential scanning calorimetry. Activation energy (Ea) was obtained through Kissinger and Ozawa methodsItalic text respectively, and reaction order(n) was educed by Crane equation. The results showed that the addition of MWCNT-P enhanced the cure reaction of DGEBA with 4,4'-methylenedianiline, compared with pure epoxy system, epoxy containing MWCNT-P exhibited a lower activation energy. Both systems presented the same reaction orders, which indicated MWCNT-P did not change the auto-catalytic cure reaction mechanism of the epoxy resin.
With triphenylphosphine oxide as a raw material,tri(3-aminophenyl)phosphine oxide was synthesized through nitration and reduction reaction. Novel phosphorus-contained hyperbranched polyamides were prepared from tri(3-aminophenyl)phosphine oxide(B3)and hexanedioic acid(A2)via A2+B3 solution polymerization. The effects of reaction conditions on the intrinsic viscosity of the hyperbranched polyamides were investigated. The structures of polymerization products were characterized with FTIR and NMR. Their thermal behaviors were measured with differential scanning calo-rimetry(DSC)and thermogravimetric analysis(TGA).
Multi-walled carbon nanotubes(MWCNTs)were oxidized with mixed acid,and then were functionized with phosphorus-containing compound 2-(6-oxido-6,H-dibenzoxa phosphorin-6-yl)-1 ,4-dihydroxy phenylene(DOPO-HQ). The functionalized carbon nanotubes(MWCNTs-P)were used to modify epoxy resin. The effects of MWCNTs and MWCNTs-P on the mechanical properties and the flame retardancy of the epoxy resin were compared. The results showed that both MWCNTs and MWCNTs-P can improve the mechanical properties of the epoxy resin,while the modification effect of MWCNTs-P was better. When the MWCNTs-P content was 0.5%,the impact strength of the epoxy resin increased by 232%. SEM images showed that the addition of carbon nanotubes improved the toughness of the epoxy resin. The tests of tensile properties and bending performance of the composites indicated that the best content of MWCNTs-P was 1.0%. Limiting oxygen index(LOI)test revealed that MWCNTs-P can improve the flame retardancy of the epoxy resin,and when MWCNTs-P content was 0.5%,the LOI reached to 30.2%.
锦城春熙路,有许多金店.在一家名为酥酥的金店里,有个年轻的女人正往纤手上套戒指.是一只米字花纹的铂金戒指,小巧秀美.年轻女人把五指伸开,眯着眼睛欣赏着.金店小姐轻轻说:你的手,配这款戒指.真好看!年轻女人喜滋滋地问:是吗?好看吗?那,就是它了吧!金店小姐递给她一张发票,她看了看,忽然娇笑道:小姐,能不能改成二百六十元?二百五,太难听了呀!金店小姐一边摇头一边掩嘴笑了起来.
很久没听电台的节目了,忽然听到,有点恍惚.在空空的小屋,光有床和桌子是不够的,虽然这些东西也可以帮助人们混过时间,比如睡眠和写作什么的.人,一个人住的时候是需要伴儿的,人的伴儿可以不是人,可以找一个替代物,活的猫狗或鸟儿就比较好.有人不愿养宠物,那他或她就可以弄个音响或彩电之类的东西,帮自己混时间.我懒,又没有钱,选的只能是最次的伴儿了:收音机.
第一幕:<约翰·克利斯朵夫>中 两列火车在一个小站错过,两个人也错过. 是1979年或者1978年的冬天,我有10元钱,去春熙路买棉鞋,结果却买了这本书,精装本四卷,当时很喜欢,现在不再想读第二遍.只有两个人错过的场景不能忘记.
