炭纤维前驱体聚丙烯腈原丝的研究

控制共聚单体的进料速率,不同的共聚单体对制备聚丙烯腈原丝的聚合反应有不同的影响。本文采用Ｘ－射线衍射、热分析及其它常规方法对炭纤维前驱体聚丙烯腈原丝的结构和性能作了研究。丙烯酸甲酯和甲基丙烯酸的加料速率对聚合反应及聚丙烯腈原丝的性能影响不大,而亚甲基丁二酸则影响很大。     

差示扫描量热（DSC）在高聚物研究中的应用

本文综述了我们在高聚物研究中应用DSC的一些结果,着重阐述了这一方法在研究共混和增塑、结晶高聚物熔融行为表征与应用、结晶动力学,以及大分子反应和添加剂作用等四方面的应用。     

DSC法测定聚乙烯结晶度的研究

研究了用DSC法测定聚乙烯（PE）结晶度的理论和新方法，通过X射线衍射（WAXD）及常规DSC法对测得的不同PE的结晶度进行了对比，探讨了DSC技术对测定高聚物结晶度的合理性，通过调制式DSC（MDSC）对PE热容的研究，证明了在低温下存在着小晶片的熔融，进而能显著影响所测定的PE的结晶度，最后提出了由于PE结晶度的大小与环境温度密切相关，故用DSC技术测定其结晶度时，选择基线的温度范围具有重要意义。     

不同共聚单体与丙烯腈的共聚合及其表征

采用四种共聚单体衣康酸(IA)、丙烯酸甲酯(MA)、丙烯酰胺(AM)、甲基丙烯酸甲酯(MMA)分别与丙烯腈(AN)进行自由基溶液共聚合,讨论了不同共聚单体对聚合反应动力学及所得纺丝原液的粘度的影响,对聚合物的热性能进行了DSC分析,考察了不同共聚单体对聚丙烯腈原丝热性能的影响。结果表明:AN/IA体系随IA含量的增加其反应速率明显下降;与其它单体相比AM更可能有效地降低聚丙烯腈原丝的预氧化温度,缓和放热,而衣康酸次之。同时,IA含量过大,会导致原丝预氧化时的降解。     

共聚甲醛序列结构与热稳定性能的研究

用核磁共振(NMR)、差示扫描量热法(DSC)、热失重(TGA)、偏光显微镜及力学性能测试研究了共聚甲醛YM-1和YM-2的序列结构、氧次甲基均聚单元序列长度及氧乙烯含量对其热稳定性和力学性能的影响。结果表明，YM-1的TTT均聚结构序列的摩尔分数、氧次甲基的序列长度分别为62．53％和5．82，两者均高于YM-2；而YM-2的氧乙烯比YM-1高23．3％，熔点(Tm=163．9℃)和结晶度(Xc=59．6％)较YM-1低；这表明在共聚甲醛中增加氧乙烯结构单元，其TTT结构含量和氧次甲基序列长度减小，分子链的规整性降低而不利于聚甲醛的结晶，使结晶度和结晶的完善程度降低。YM-1具有更为完整的球晶结构．其力学性能高于YM-2。     

用SEM研究PAN原丝的表面缺陷

有机聚丙烯腈纤维（PANF）经过一系列高温热处理（HTT）转化为无机碳纤维（CF），CF属于脆性材料，其抗拉强度受控于各类缺陷，它的缺陷大致可分为两大类，一类是先天性缺陷，即由原丝引入，另一类是后天性缺陷，在后处理过程中引入，本文主要是用扫描电子显微镜（SEM）研究PAN原丝的表面缺陷。     

DSC检测过程影响因素的探讨研究

通过实验分析了升温速率、气体流量、试样填充量、试样粒度及试样摆放位置等DSC测试结果的影响因素,取得满意的结果,具有实际指导意义.     

用DSC优化轮胎硫化周期的新方法

轮胎胶料的硫化程度对其使用性能影响重大。已尝试用差示扫描量热（DSC）法来推断轮胎胎面胶料的硫化（包括过硫）程度。未硫化胶料用DSC进行时间-温度分析时，可以得到由聚合物、硫化剂和其他添加剂特征决定的放热曲线（焓△H）。     

Studies of the Effect of Comonomers on the Microstructure of Polyacrylonitrile in Radical Polymerization Using NMR Spectroscopy

Abstract

The free radical polymerization method has been employed to synthesize homopolymers of acrylonitrile (AN), its copolymers with methylacrylate (MA) and terpolymers containing itaconic acid (IA) in homogeneous solution (aqueous solution of sodium thiocyanate and dimethylsulfoxide media) and aqueous redox slurry system. ¹³C NMR was used to characterize these polymers in terms of steric configurations in order to study the effect of co and ter monomers on microstructure of polyarylonitrile both at low and high conversions. The study showed no significant change in microstructure of polyacrylonitrile on the introduction of MA and IA. Different techniques of polymerization for ACN-MA-IA had no effect on the microstructure of terpolymer. ¹H NMR and IR techniques were used to determine the composition of copolymers and a good agreement was observed between the results from the two techniques. The presence of unsaturated carboxylic acid monomer (IA) was confirmed by ¹H NMR.     

DSC study on the effect of cure reagents on the lignin base epoxy cure reaction

The cure reactions of liquid lignin base epoxy resin (LEPL) with three different curing agents, viz., methylhexahydrophthalic anhydride, maleic anhydride, and 2‐methyl‐4‐methylimidazole (EMI‐2,4), were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry. Cure kinetics was evaluated using the multiple heating rate Kissinger method. The reactivities of the three curing agents were compared based on kinetics results obtained by DSC. FTIR spectra of these curing systems were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

High‐temperature DSC study of polyacrylonitrile precursors during their conversion to carbon fibers

The evolution of structure, the changes of properties during the preoxidation, precarbonization, and carbonization of different polyacrylonitrile (PAN) precursors were firstly studied in detail by means of using high‐temperature differential scanning calorimetry (DSC) to characterize with continuous heating from 25 to 1400°C. It was essential to study the thermal behavior of PAN precursors so that proper temperature was determined. Three precursors with different composition, P1: acrylonitrile/itaconic acid (AN/IA) = 98/2 (wt/wt); P2: acrylonitrile/acrylamide (AN/AM) = 98/2 (wt/wt); P3: acrylonitrile/ammonium salt of itaconic acid (AN/AIA) = 98/2 (wt/wt) were, respectively, selected in this study. Comparative results of the DSC curves showed that the heating history influenced greatly the heat quantities released and exothermic position at low temperature of DSC curve, but influenced slightly at higher temperature. Aromatic index, carbon yield (W_c) and weight loss (η) can be calculated. After adjusting the temperature in preoxidation and precarbonization and carbonization technology depending on high‐temperature DSC, the high performance carbon fibers were obtained that tensile strength is 3.56–4.16 GPa, modulus is 235–243 GPa. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

聚丙烯腈纤维体积密度影响因素研究

应用X射线衍射仪并结合密度梯度法,考察了纺丝干燥致密化工序对聚丙烯腈纤维的体积密度的影响.结果表明,在聚合组分不变的情况下,随着纺丝干燥致密化工序的变化,聚丙烯腈纤维的体积密度也随之而变化,聚合组分为AN-co-IA、MA三元共聚物体系,纺丝干燥致密化温度在125℃,热拉伸倍率为0.03时,聚丙烯腈纤维的体积密度达到最大值为1.219 g/cm3.     

用DSC法评价不溶性硫磺的热稳定性

研究利用差示扫描量热仪(DSC)法评价不溶性硫磺的热稳定性,分析了试验结果的影响因素:升温速率、保温时间、保温温度和样品质量等几个方面,最后与化学分析法(化学法)的试验结果进行了对比。研究表明:差示扫描量热仪(DSC)具有能快速、准确和客观地评价不溶性硫磺热稳定性的特点;在测定结果方面,相比化学分析法而言,其准确度更高、精密度更好,完全可以取代传统的化学分析方法,作为控制不溶性硫磺质量的一种有效手段。     

聚苯胺/聚丙烯腈共混体系的微观结构与流变性能研究

首先由乳液聚合制备十二烷基苯磺酸(DBSA)掺杂的聚苯胺(PANI),然后以三氯甲烷/二甲基亚砜 (DMSO)为混合溶剂,制备不同组成的PANI-DBSA/PAN的共混溶液。对共混溶液的流变性能进行了测试, 并研究了共混体系的微观结构与流变性能的关系。     

牵伸倍数分配对PAN原丝及其碳纤维力学性能影响

通过单变量试验,并结合取向度、表面电镜等对丝束性能检测,分析了PAN原丝生产中牵伸倍数分配对原丝及其碳纤维力学性能的影响。结果表明:原丝取向度的提高,主要取决于蒸汽牵伸倍数。随着蒸汽牵伸倍数的增加,分子链取向规整性增强,原丝的取向度得到提高,原丝的整体强度就会上升,其碳纤维的强度及模量也会随之提升。     

Effect of LiCl on electrospinning of PAN polymer solution: theoretical analysis and experimental verification

Polyacrylonitrile(PAN) is used to study the effect of surface charge on electrospinning by adding LiCl. The theoretical analysis shows that the relationship between radius r of jet and the axial distance z from nozzle follows an allometric law in the form r∼z^−0.5 in case of full surface charge, and the scaling exponent becomes larger for partly charged fibers in electrospinning.     

DSC investigation of the hindered effect on curing behavior for epoxy-phenol/MMT nanocomposites based on the acidic octadecylamine modifier

The hindered curing behavior of epoxy-phenol mixtures with the presence of 18MMT (modified by acidic primary octadecylamine) using triphenephosphine (TPP) as a catalyst was investigated by DSC. The mechanism proposed is based on the analysis of these obtained curing behaviors with DSC experiments by changing the components in the epoxy-phenol/18MMT blends. Due to the reaction between TPP and the active H in 18MMT, the catalytic effect of TPP is reduced greatly, which pushed the epoxy resin cured by 18MMT at higher temperature. Such mechanism can depict the delayed curing reaction with incorporation of different amounts of 18MMT correctly. By changing TPP contents and the type of organic modifier bearing no active H, the subsequent resulted curing reaction is quit in good agreement with those predicted by the proposed mechanism, which supports our hypothesis in further.     

用灰色关联方法分析碳纤维原丝性能的影响因素

利用灰色关联度计算方法 ,对制备聚丙烯腈原丝的原液性能及纺丝工艺参数与原丝性能之间的关系进行了灰色关联分析。结果表明 :影响原丝强度的因素 ,关联度 (影响因子 )由大到小排列为总牵伸倍数、转化率、固含量、喷头牵伸比、凝固浴温度、分子质量 ;影响原丝结构性能参数的因素 ,关联度由大到小排列为总牵伸倍数、喷头牵伸比、固含量、转化率、凝固浴温度、分子质量