聚丙烯腈基超细碳纤维毡的制备及其表征

采用静电纺丝法制备了不同黏均分子质量(Mη)的聚丙烯腈(PAN)超细纤维毡,并通过280℃预氧化和900℃碳化进一步制备超细碳纤维毡。讨论了Mη对纤维制备的影响,发现PAN的Mη大于3×105则不利于静电纺丝,小于5×104则纤维毡发脆,无法进一步加工处理成碳纤维毡。用场发射扫描电镜、红外光谱、X-射线衍射对纤维毡进行表征,结果表明:随着PAN相对分子质量的升高,碳纤维的直径和得率增大。此外,抗拉强度测试表明:随着相对分子质量的增大,超细碳纤维毡的抗拉强度增加。     

用橡胶加工分析仪/凝胶渗透色谱仪测定NR的相对分子质量

研究橡胶加工分析仪测定的NR复数粘度(η*)与凝胶渗透色谱仪测定的NR相对分子质量(M)之间的关系。结果表明:用Mark-Houwink方程η=kMa可以描述NR的η*与M之间的关系,二者之间有较好的线性相关性;当试验频率增大,常数k增大,a减小;用η*计算的NR数均和重均相对分子质量与凝胶渗透色谱仪测定结果的相对误差分别在2.78%～5.45%和1.16%～2.82%之间。     

UHMWPE冻胶纺丝中的降解行为及其对纤维性能的影响

采用双螺杆混炼挤出机溶胀、溶解和挤出纺丝技术制备超高相对分子质量聚乙烯(UHMWPE)冻胶纤维,经热管拉伸得到UHMWPE纤维,研究了冻胶纺丝工艺及后续热拉伸对UHMWPE纤维黏均相对分子质量(M_η)的影响,以及M_η与UHMWPE成品纤维力学性能、热性能、抗蠕变性能及耐磨性能的关系。结果表明:螺杆转速、溶解温度及溶液浓度变化引起的物料高温停留时间和受剪切强度变化对UHMWPE分子降解程度有很大的影响,超倍热拉伸工艺对UHMWPE分子降解影响不大;在UHMWPE溶解均匀的情况下,纤维强度、抗蠕变及耐磨性能随冻胶纤维M_η的增大而增大,且纤维结晶度增加,熔点升高;而UHMWPE溶解条件不佳时,冻胶纤维M_η最高,但纤维表面呈现不均匀凸起,纤维综合性能也变差。     

纳米铝填充聚苯乙烯熔融纺丝及其性能研究

采用分散聚合法合成了聚苯乙烯(PS)及在PS中掺杂纳米铝(Al NPs)的PS/Al NPs复合材料,采用熔融纺丝法制备了PS及PS/Al NPs纤维,并对其结构与性能进行了研究。结果表明:重均相对分子质量(Mw)为(5~25)×104的PS,在220~270℃熔融纺丝,制得PS纤维直径可达25μm,断裂强度为1.2 c N/dtex,断裂伸长率为4.8%;PS/Al NPs复合材料中Al NPs在PS中分散均匀,PS内部中的Al NPs抗氧化能力较好;与相同Mw的PS纤维比较,PS/Al NPs纤维的玻璃化转变温度提高了4℃,断裂强度提高了4.1%,断裂伸长率提高了13.3%。     

用Mark-Houwink方程描述环氧化天然橡胶复数粘度与相对分子质量的关系

研究橡胶加工分析仪测试的环氧化天然橡胶(ENR)复数粘度(η*)与凝胶渗透色谱(GPC)仪测试的相对分子质量(M)之间的关系.结果表明:用Mark-Houwink方程η=kMa可以描述ENR的η*与M的关系,二者之间有较好的线性相关性;随着试验频率的增大,Mark-Houwink方程常数k增大,a减小;用η*计算的ENR数均和重均相对分子质量与GPC仪测定结果的相对误差分别在0.401 8%～4.045 2%和1.009 6%～8.013 8%之间.     

超高相对分子质量聚丙烯腈基中空纤维膜的制备工艺研究

以超高相对分子质量聚丙烯腈为原料 ,通过凝胶纺丝方法制备中空纤维膜。讨论了纺丝方法、相对分子质量和工艺条件 (纺丝原液浓度、气隙长度 )对中空纤维膜力学性能的影响 ;用 SEM测定了所制备的中空纤维膜的形态结构     

粒料法合成不同相对分子质量和软段的聚氨酯分散体研究

以异佛尔酮二异氰酸酯(IPDI)为硬段、二羟甲基丙酸(DMPA)为亲水单体,采用粒料法合成了不同Mη(黏均相对分子质量)和不同软段的PU(聚氨酯)离聚物粒料,并制备了固含量约为40%的PUD(PU分散体)。结果表明:PU的Mη随R值[R=n(-NCO)/n(-OH)]增加呈先升后降态势;PU的Mη越高,PUD的平均粒径越小,粒径分布越窄,黏度越大;PUD粒子呈大小不一的球形结构,并且PU的Mη越高,PUD胶膜的拉伸强度越大;聚酯型PUD胶膜的拉伸强度大于聚醚型PUD,并且前者的软段和硬段之间相容性较好,而后者的软段和硬段之间因出现相分离现象而相容性较差;PUD胶膜的吸水率均不超过5.93%,说明其耐水性能优异。     

熔体法同轴电纺PP/(PLA+PEG)核壳超细纤维

采用自制的熔体同轴静电纺丝装置,通过控制壳层聚丙烯(PP)与核层聚乳酸(PLA)+聚乙二醇(PEG)的流量大小,制备不同直径、不同结构和不同热焓的核壳结构纤维。研究结果表明,在总流量不变的情况下,核层PLA+PEG流量增加,获得的纤维直径增大,1 g/h时平均直径为2.4μm,5 g/h时为6μm;PLA+PEG与PP流量相差越大,纤维直径越不均匀,内外层结构也越不均匀;PLA+PEG流量增大,制备的纤维热焓增大。为获得直径均匀、结构均匀、热焓较大的核壳结构超细纤维,PLA+PEG与PP流量比值控制在1~2倍较佳。     

硫化锌铜/氘代聚苯乙烯/PVDF超细纤维膜的制备和荧光性能研究

以硫化锌铜荧光粉、聚苯乙烯(PS)和聚偏氟乙烯(PVDF)为原料,通过静电纺丝法(电纺)制备了荧光超细纤维膜,通过扫描电子显微镜(SEM)、X射线衍射仪、差示扫描量热仪(DSC)和荧光分光光度计研究了荧光粉含量对纤维形貌、荧光性能的影响。结果表明,随荧光粉含量的增加,纤维中的荧光粉颗粒量增加,纤维膜中荧光粉晶体含量增加,纤维膜发光强度增加。在保证电纺过程的可纺性和所得纤维膜的基本力学性能的前提下,在荧光粉含量为50%时,所得纤维膜的荧光性能最好。在此优化条件下,制备了硫化锌铜/氘代聚苯乙烯/PVDF超细纤维膜,并测试了其荧光性能。结果表明,氘代聚苯乙烯对纤维膜的荧光性能无影响。     

静电纺丝法制备PHB纤维膜及其性能表征

利用静电纺丝法制备了聚羟基丁酸酯( PHB)纤维膜,探讨了不同溶剂体系的PHB纺丝溶液性质及其纤维直径分布和纤维形貌;研究了加热和蒸气灭菌对PHB纤维膜的力学性能和亲水性的影响.结果表明:采用氯仿/N-N二甲基甲酰胺(DMF)复合溶剂体系,提高了PHB纤维膜的可纺性,纤维平均直径由2.3μm下降到1.0μm,但纤维粗细...     

Phase separation and segregation morphology of PCL/PS blends: Quantitative effect of the crystallization temperature,composition, and molecular weight of PS

The phase diagrams for blends of semicrystalline poly(ε‐caprolactone) (PCL) with amorphous polystyrene (PS) were determined and it was noticed that when molecular weight increases, the critical composition diminishes while its temperature increases. That is the same effect that produces the increase in the polydispersity of PS. From the fitting of phase diagrams of blends of PCL with oligomers and homopolymers of PS, taking into account the polydispersity, it was possible to conclude that the miscibility in these systems is due only by entropic effects. The crystalline fraction as well as the interlamellar spacing increased with crystallization temperature while the volume fraction of the amorphous PCL in the interfibrillar regions increases for the pure PCL and in its blends with low concentration of PS. Increasing the mass fraction of PS increases the average long spacing (L) till a weight fraction of 60%, for higher mass fractions L is almost constant indicating the interfibrillar segregation of PS. The PCL lamellar morphology is not affected when the molecular weight of PS employed is similar or higher than the molecular weight of PCL. If the PS has a higher molecular weight its penetration into the structure is inhibited. POLYM. ENG. SCI., 57:1062–1072, 2017. © 2016 Society of Plastics Engineers     

PS/PETG共混物的流变性能和发泡行为研究

采用密炼机制备了聚苯乙烯(PS)和聚对苯二甲酸乙二醇酯1,4环己二甲醇酯(PETG)共混物;以超临界二氧化碳(CO2)为物理发泡剂,采用釜压法制备了PS和PS/PETG共混物发泡试样。通过旋转流变仪、扫描电子显微镜对PS和PS/PETG共混物的流变性能和泡沫的泡孔形态进行了表征。结果表明,加入PETG没有对PS的流变性能产生明显的影响,但对PS泡沫的泡孔形态影响显著,加入10 %的PETG时,其平均泡孔直径由纯PS的2268 μm降至758 μm,泡孔密度由345×108个/cm3提高到447×109个/cm3,泡孔尺寸分布明显变窄,说明PETG在PS中起到明显的气泡成核作用。     

L-乳酸低聚物的异氰酸酯扩链反应工艺研究

采用直接熔融缩聚法制备L-乳酸低聚物。在氮气氛围下,使用六亚甲基二异氰酸酯(HDI)、二苯基甲烷二异氰酸酯(MDI)作扩链剂,研究了反应时间、温度、反应官能团配比、低聚物粘均相对分子质量(Mη)等对扩链反应的影响,对扩链产物进行了红外光谱表征及差示扫描量热分析。结果表明:HDI和MDI对L-乳酸低聚物均有较好的扩链效果,扩链反应规律基本相同;HDI的扩链效果优于MDI,扩链反应速率快,扩链时间短,扩链产物Mη高、熔点高、热性能好;较佳扩链反应工艺参数:nNOC∶nOH为1:1,反应温度165℃,HDI扩链时间20 min、MDI扩链时间30 min,L-乳酸低聚物M越高,扩链产物M越高。     

PS对PS/CF复合材料SLS烧结件力学性能及成型精度的影响

以聚苯乙烯（PS）作为基体材料制备了聚苯乙烯/碳纤维（PS/CF）复合粉末材料,在激光功率为30 W,预热温度为80 ℃和分层厚度为0.25 mm等条件下,研究了基体材料的粒径及含量对PS/CF复合材料选择性激光烧结件的力学性能及成型精度的影响。结果表明,制得的PS/CF复合粉末材料的粒径满足选择性激光烧结工艺（SLS）的要求;当基体材料的平均粒径为75 μm,PS与CF的质量比为9∶1时,PS与CF之间的融合效果最佳;此时弯曲、拉伸和冲击强度分别可达6.88、2.97 MPa和298 kJ/m2,x向、y向及z向的尺寸偏差绝对值仅为0.8 %、0.22 %、1.6 %;与相同粒径的纯PS相比,弯曲、拉伸和冲击强度分别提高了62.06 %、74.29 %、83.95 %,x向、y向及z向尺寸精度分别提高了5.44 %、69.44 %、81.34 %。     

基于叶片挤出机加工的PP/PS共混体系相形态研究

应用最新研制的叶片挤出机,研究了PP/PS共混体系经叶片挤出机挤出的相形态演变过程,在此基础上对比分析了叶片挤出机和单螺杆挤出机加工PP/PS共混体系的最终相形态,以及挤出转速对PP/PS共混体系分散混合效果的影响。结果表明,和单螺杆挤出机相比,经叶片挤出机加工的共混物的分散相粒径更小、更均匀,且受共混体系组分的影响更小。叶片挤出机的转速,会影响PP/PS共混体系的分散混合效果。在本实验中,加工转速为60 r/min时,PP/PS(70/30)共混体系的分散相粒径平均尺寸达到最小,约为0.65μm,且分散最均匀。     

In situ gradient nano-scale fibril formation during polypropylene (PP)/polystyrene (PS) composite fine fiber processing

The nano-scale dispersed fibrils with gradient distribution in PP/PS composite fine fibers were observed by in situ formation during its melt spinning process. The morphology development of polyblends, from granule to as-spun fiber as well as drawn fiber with various PS content from 2 to 8 wt% were investigated. The morphology conversion of PS dispersed phase from ellipse to gradient nano-scale fibril along the radial direction of as-spun composite fibers took palace at 4 wt% by weight of PS component, suggesting the presence of break-up in fiber center and the limited coalescence, especially in 8 wt% PS as-spun composite fibers. This morphology diversity was attributed to the radial variation of parameters including temperature, viscosity, axial velocity and stress in spinning path and was in good agreement with the droplet deformation criteria based on the reduced capillary number. In addition, the post hot-drawing process slightly influence the size and distribution of PS phase in cross-section of composite drawn fibers, while the rheological properties of PP, PS and polyblends were found to be correlated to the morphology of PP/PS composites.     

聚苯乙烯/纳米TiO2/SEBS三元复合材料的制备及性能研究

采用熔融共混法制备了聚苯乙烯/纳米二氧化钛/氢化苯乙烯乙烯丁二烯苯乙烯共聚物（PS/纳米TiO2/SEBS）三元复合材料。研究了SEBS和纳米TiO2用量对复合材料力学性能、扭矩以及热性能的影响。利用扫描电子显微镜对复合材料冲击断面的微观形貌进行了研究。结果表明,PS/纳米TiO2/SEBS复合材料的冲击强度随SEBS含量的增加逐渐增大,拉伸强度随SEBS含量的增加逐渐减小。当PS与纳米TiO2的质量比为97/3、SEBS的用量为8份(质量份,下同)时,复合材料的综合力学性能最佳,其冲击强度为5.626 kJ/m2,拉伸强度为25.623 MPa;加入纳米TiO2和SEBS都使复合材料的热性能得到了提高;复合材料的最大扭矩与PS相比下降了17 N·m,平衡扭矩均为7 N·m;SEBS以颗粒状镶嵌到基质中,断口形貌为典型的韧性断裂。     

挤出法PS发泡板材专用树脂的结构与性能

分析挤出法聚苯乙烯(PS)发泡板材对树脂性能的要求,并对比了市场应用较好的同类产品的分子结构、加工流变性能,开发了挤出法PS发泡板材专用树脂680X。680X具有较高的相对分子质量和适当的相对分子质量分布,因而具有较高的熔体强度,其力学性能和加工性能优良,制品的性能符合挤出法PS发泡板材的要求。     

Formation of bead‐free and core–shell superfine electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer

This work presents a new way of preparing bead‐free and core–shell superfine polymer electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer. For the electrospinning of polystyrene (PS)/CHCl₃ solution, the bead‐free fiber cannot be obtained until the PS concentration is above 0.25 g/mL but its average diameter is above 10 μm. Using polyamide 6 (PA6) as an additive, the critical concentration capable of forming bead‐free fiber greatly decreased and core–shell fibers with PA6 as the core and PS as the shell were obtained due to the driving effect of high spinability of PA6. The introduction of a copolymer (PS‐co‐TMI) of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) can react with amine of PA6 to form the copolymer of PS and PA6 as an interfacial compatibilizer. As a result, it can further enhance the dispersion and deformation of minor component PA6 into uniform microfiber core, and drive PS to uniformly cover the surface of PA6 fibers, and finally form bead‐free and core–shell superfine fibers. POLYM. ENG. SCI., 59:1437–1444 2019. © 2019 Society of Plastics Engineers