中国专利北大核心

一种聚丙烯腈基碳纤维原丝及其制备方法本发明公开了一种聚丙烯腈基碳纤维原丝及其制备方法,原料组成为:包含N原子的单体100.0 phr、偶氮二甲酰胺引发剂0.2~0.8 phr。以偶氮二甲酰胺为引发剂,引发结束后留在分子链末端的N原子与单体中的N原子配合促进预氧纤维梯形结构向二维芳香稠环结构的转变,共聚单体中的N原子有利于分子链间交联反应,同时采用连续滴加、分段聚合的方式,确保了聚合物结构均匀一致,提高碳得率。     

偶氮引发剂对PAN及其原丝结构和热稳定化行为的影响

以丙烯腈和衣康酸为单体,以二甲基亚砜(DMSO)为溶剂,分别以含脒基的偶氮二异丁脒盐酸盐(AIBA)、偶氮二异丁腈(AIBN)为引发剂,采用溶液聚合法,制备了具有不同端基结构的丙烯腈与衣康酸共聚物PAN-AIBA和PAN-AIBN;经湿法纺丝得到聚丙烯腈(PAN)原丝,研究了AIBA,AIBN引发剂的分子结构对PAN相对分子质量、原丝结构、热行为的影响。结果表明:采用溶液聚合的方法,以AIBA为引发剂可制得适于湿法纺丝的PAN-AIBA,其环化反应的起始温度较PAN-AIBN的提前了20℃,放热峰较宽;与PAN-AIBN相比,PAN-AIBA原丝的晶粒尺寸更大、结晶度较高;在低温热稳定化条件下,PAN-AIBA原丝表现出优于PAN-AIBN的较高热环化效率,而在高温热处理时,二者热环化效率相近;通过利用AIBA引发剂在PAN大分子结构中引入脒基,有望改善PAN原丝的低温热稳定化行为。     

浅谈提高聚丙烯腈基碳纤维性能的几种关键技术

从国外研究较多的共聚单体、聚丙烯腈原丝的改性、上油油剂等三个方面论述了提高聚丙烯腈基碳纤维性能的几种关键技术。聚丙烯腈原丝的热性能与共聚单体的种类和加入量有重要关系。共聚单体的加入促进纤维预氧化反应 ,使碳纤维性能和炭化收率都得到提高。各种各样的化学试剂用于改性聚丙烯腈原丝后 ,对改善最终碳纤维的结构和性能有重要的作用。油剂的使用对聚丙烯腈原丝的质量 ,如耐热性、亲水性、集束性、分纤性及加工毛丝率等有重要的影响     

聚丙烯腈基碳纤维的制备工艺过程和纤维结构研究

采用丙烯腈(AN)与丙烯酸(AA)自由基溶液共聚合,以偶氮二异丁腈(AIBN)为引发剂,在二甲基亚砜(DMSO)中合成了聚丙烯腈纺丝溶液,经湿法纺丝制得聚丙烯腈(PAN)原丝,经过热稳定化和炭化得到聚丙烯腈基碳纤维,拉伸强度达到3.2GPa,杨氏模量为236GPa.采用扫描、透射电镜对纤维的结构进行表征.     

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。     

引发剂AIBN对高性能炭纤维PAN原丝聚合反应影响

以丙烯腈(AN)为主单体,丙烯酸甲酯(MA)、甲叉丁二酸(IA)为二三单体,偶氮二异丁腈为引发剂,进行溶液自由基聚合。考察了引发剂浓度和加入方式对三元共聚合的影响。研究得出,温度为61℃,引发剂浓度为0.75%,升温前加入引发剂,合成了数均分子量为15.5万,重均分子量为33.6万,并且分子量分布指数小于3.0,单体转化率高于90%,增比黏度为1.39的高性能炭纤维用原丝纺丝液。     

干喷湿纺法制备T700级聚丙烯腈基碳纤维

采用丙烯腈、氨化试剂A、丙烯酸甲酯为聚合单体,以偶氮二异丁腈为引发剂,在溶剂二甲基亚砜中合成了聚丙烯腈原丝纺丝液,经干喷湿纺法纺丝制得聚丙烯腈原丝,经预氧化和炭化得到了T700级高性能聚丙烯腈基碳纤维。采用扫描电子显微镜,差示扫描量热仪,电子万能材料试验机对纤维的性能进行了研究。研究了空气层距离、喷丝头长径比、凝固浴浓度、空气拉伸比对干喷湿纺法制备纤维性能的影响。在空气层距离为40mm、凝固浴浓度为70%、喷丝头长径比为10.0、空气拉伸比为1.8条件下,采用干喷湿纺法制得的T700级聚丙烯腈基原丝及碳纤维的表面光滑、无沟槽,截面形貌为圆形;原丝的拉伸强度可达8.7cN/dtex,拉伸弹性模量可达154.7cN/dtex,碳纤维的拉伸强度可达5 750MPa,拉伸弹性模量可达220GPa。     

超声辐射丙烯腈的无皂乳液聚合

以过硫酸铵为引发剂,用超声波引发丙烯腈单体进行无皂乳液聚合,研究了单体浓度、引发剂浓度、反应时间对单体转化率的影响情况,并对聚合物进行了IR、TEM表征,结果显示聚丙烯腈乳胶粒尺寸均匀,约为50nm。     

用DSC研究选择聚丙烯腈原丝的共聚单体

本文主要利用差示扫描量热分析(DSC)研究了聚丙烯腈的共聚物及其原丝的热性能，研究结果发现国产原丝具有相似的放热单峰，而日本某公司的原丝具有两个峰，分峰使聚丙烯腈原丝放热峰宽化，避免了在预氧化、碳化时放热集中产生熔化、断丝现象．聚丙烯腈原丝的纺丝、溶解、氨改性等加工过程不能明显改变其放热峰的形状，而共聚单体的种类和组成配比才是最重要的因素，通过适当的共聚单体选择、配比设计可以制得具有与日本原丝放热峰相似的聚丙烯腈聚合物或原丝。     

合成中等分子质量聚丙烯腈聚合反应的研究

以NaClO_3/NaS_2O_5为氧化—还原引发剂,进行了丙烯腈(AN)与衣康酸(ITA)等几种不同单体的的水相沉淀聚合,制得了中等分子质量的聚丙烯腈(PAN)聚合体。系统地考察了引发剂浓度及配比、聚合温度、聚合时间、单体浓度以及第三单体甲基丙烯磺酸钠(MAS)的加入等工艺条件对聚合转化率和聚合物相对分子质量的影响。     

聚丙烯腈基碳纤维的制备工艺过程和纤维结构研究

采用丙烯腈（AN）与丙烯酸（AA）自由基溶液共聚合,以偶氮二异丁腈（AIBN）为引发剂,在二甲基亚砜（DMSO）中合成了聚丙烯腈纺丝溶液,经湿法纺丝制得聚丙烯腈（PAN）原丝、经过热稳定化和炭化得到聚丙烯腈基碳纤维,拉伸强度达到3．2GPa,杨氏模量为236GPa。采用扫描,透射电镜对纤维的结构进行表征。     

Manufacture of carbon fibers from polyacrylonitrile precursors treated with CoSO4

Free‐radical solution copolymerization of itaconic acid and acrylonitrile was carried out in DMSO using azodiisobutyronitrile as an initiator, changing the feed rate of itaconic acid. The resulting polymerization solution was spun to form polyacrylonitrile (PAN) precursors of carbon fibers. The precursors were treated with a CoSO₄ aqueous solution on‐line. The structure and properties of untreated and treated PAN precursors and the resultant carbon fibers were characterized by SEM and TEM, a stabilization process, etc. It is suggested that CoSO₄ acts as a catalyst in the formation of a ladder structure and reduces the temperature of cyclization, and the carbon fibers developed from treated PAN fibers showed improvement in the tensile strength and the Young's modulus. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 153–158, 2002     

Lyocell fibers as the precursor of carbon fibers

In this work, Lyocell fibers, used as carbon fiber precursors, were investigated. Lyocell fibers used for the carbon precursors and the carbon fibers themselves were produced in our laboratory. The mechanical properties morphology and structure of the precursors and the obtained carbon fibers were studied and compared to those of rayon. The results show that Lyocell fibers have higher tenacity and modulus, and better thermal stability than rayon fibers. Scanning electron microscopy (SEM) experiments show that Lyocell precursors have round cross‐sections and fewer defects in the fibers, while rayon fiber has an oval cross‐section and many defects. Wide angle X‐ray diffraction (WAXD) results for the Lyocell precursors indicate that the degree of crystallinity of the Lyocell precursor is higher than that of a rayon precursor. They also show that Lyocell based carbon fibers have better mechanical properties than those that are rayon‐based. WAXD data of the obtained carbon fibers show that the crystallinity of Lyocell‐based carbon fiber is higher than that of rayon‐based carbon fiber. It is concluded that the Lyocell fibers are better precursors for carbon fibers than rayon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1941–1947, 2003     

UHMWPE纤维用氯丁橡胶粘合剂的制备及应用研究

研究了丙烯酸丁酯(BA)和氯丁橡胶(CR)的接枝共聚合反应,用正交设计方法探讨了引发剂用量、丙烯酸丁酯用量、温度和时间对产物性能的影响,用红外光谱(FT-IR)和示差扫描量热仪(DSC)对产物的结构和性能进行了表征。应用结果表明改性氯丁橡胶粘合剂可用于超高相对分子质量聚乙烯纤维的上胶。     

Hollow carbon fibers with tailored porosity and rim-thickness

The synthesis of compact and hollow carbon fibers with variable porosity and rim thickness is described. Block copolymers were prepared by anionic copolymerization of 1,3-cyclohexadiene with ε-caprolactone. By variation of the initiator, a block copolymer (P1) that contains both 1,2-cyclohex-3-enylene and 1,4-cyclohex-2-enylene repeat units (≈1:1) and a block copolymer (P2) consisting of >98% of 1,4-cyclohex-2-enylene units was prepared. Both block copolymers were melt-spun into monofilament fibers. After spinning, stabilization of the fibers was successfully accomplished by oxidation and electron beam treatment. Fibers based on >98% 1,4-cyclohex-2-enylene repeat units displayed a low but substantially higher degree of crystallinity than the P1-derived ones containing both 1,2- and 1,4-connected repeat units. Since P1-derived fibers were predominantly amorphous and had a diameter of about 20–25 μm, their thermostabilization resulted in fully compact carbon fibers. Vice versa, depending on the extent of electron beam treatment and fiber diameter, the more crystalline P2-derived fibers with a larger diameter of about 50 μm offered access to hollow and porous carbon fibers with variable rim thickness. The precursor fibers and the resulting carbon fibers were characterized by NMR- and Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, thermal analysis, nitrogen-sorption and X-ray diffraction.     

Graft copolymerization of styrene with carbon black-alkali metal complex

It was found that an ion radical complex is formed by the reaction of carbon black with an alkali metal (Li, Na, K) in tetrahydrofuran. The graft copolymerization of styrene with carbon black was carried out using the ion radical complexes as initiator, and free polystyrene and carbon black-polystyrene graft copolymer were obtained. The identification of the graft copolymer with carbon black was carried out by fractionation and thermal degradation. The initiation activity of the alkali metals increased in the order Li < Na < K. The effect of the particle size of the carbon black on the graft copolymerization was studied.     

过硫酸盐引发棉纤维接枝的研究

以过硫酸盐与硫代硫酸钠为引发剂,使丙烯酰胺与棉纤维进行接枝共聚,研究了过硫酸盐的加入方式和加入量对接枝反应的影响,发现采用过硫酸铵与过硫酸钾两种氧化剂、两步加入的办法能够克服体系中氧气的阻聚作用,又能得到较高的单体转化率和接枝率。     

Graft copolymerization of vinyl monomers onto silk fibers initiated by a semiconductor‐based photocatalyst

Graft copolymerization onto silk (Bombyx mori) was carried out with vinyl monomers (methyl methacrylate and acrylamide) and initiated by a semiconductor‐based photocatalyst (cadmium sulfide). The utility of a semiconductor as an initiator in free‐radical photografting and the effects of ethylene glycol and triethylamine with cadmium sulfide on graft copolymerization were explored. Depending on the reaction conditions, 10–48% grafting with methyl methacrylate and 4–26% grafting with acrylamide were achieved. The reaction conditions were optimized, and the grafted fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry analysis, and tensile strength measurements. The chemical resistance and water absorption of the grafted fibers were compared with those ungrafted fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of Functionalization of Lignocellulosic Fibers on Their Physico-Chemical and Thermal Properties

In this paper Agave fiber has been functionalized through graft copolymerization and physico-chemical and thermal properties have been investigated. The graft copolymerization of methyl methacrylate and acrylonitrile onto Agave americana fibers was carried out under pressure using ceric ammonium nitrate as redox initiator. The chemical resistance studies were carried out in hydrochloric acid and sodium hydroxide. Water absorption studies were also carried out by exposing grafted fibers to accelerated weathering under different humidity levels ranging from 40 to 95%. Characterization of functionalized fibers was done through Fourier Transform Infra Red spectroscopy, scanning electron microscopy, and X-ray diffraction techniques.     

Grafting of poly (methyl acrylate) onto sulfite pulp fibers and its effect on water absorbance

To prepare super water absorbent hydrogels of wood cellulose fibers, poly (methyl acrylate) (PMA) was copolymerized onto softwood sulfite pulp fibers using free radical initiator followed by alkaline hydrolysis. Ceric ammonium nitrate (CAN) was used as the free radical initiator. Effects of various parameters such as fiber concentration, monomer/pulp (M/pulp) ratio, CAN concentration, and reaction time on the grafting yield and on other grafting parameters were investigated. The graft conversion was the same from low to medium fiber concentration. The amount of initiator required was found to be independent of fiber concentration to achieve maximum grafting yield. Different fiber fractions (classified based on their length) have no effect on the grafting yield. The evidence of graft copolymerization was determined by using ATR‐IR spectroscopy. The X‐ray diffraction (XRD) analysis shows that grafting takes place both in amorphous and crystalline regions of cellulose fibers and the decrease in crystallinity of the grafted fibers with an increase in grafting yield was confirmed. The surface morphology of the PMA‐g‐cellulose was characterized by scanning electron microscopy (SEM). The water retention value of the hydrolyzed grafted pulp was determined based on a centrifugation technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007