尼龙6固相聚合模型及计算机模拟研究

根据尼龙6固相聚合反应机理,建立了由可逆化学反应和小分子扩散共间控制的尼龙6固相聚合动力学模型,并确定了其动力学和热力学参数。通过计算机模拟实验表明,聚合反应温度越高,预聚体尺寸越小,预聚体初始相对分子质量越高,越有利于固相增粘反应,有利于固相聚合尼龙6相对分子质量的增加。     

尼龙6固相缩聚——实验数据与模型数据的比较

研究了不同起始相对分子质量、不同含水量的圆球状尼龙6切片在不同温度和反应时间下的连续固相缩聚行为.结果说明了起始相对分子质量和温度对尼龙6的固相增黏效果影响很大,和模型得出的结论一致;而不同含水量和反应时间同样也会影响尼龙6切片的固相增黏效果.此外,结果还发现在实际生产中,切片的起始氧化温度远远低于模型推断出的起始氧化温度.实验结果为今后的模型设计和改进提供了极有参考意义的数据,同时也为固相缩聚提出了新的研究方向.     

固相缩聚生产高粘度聚酯

叙述了高粘度聚酯的发展概况以及制造工艺,并重点阐述了影响固相缩聚生产高粘度聚酯反应的主要因素。指出聚酯固相缩聚应选择合理的原料路线,严格精选切片颗粒大小及预聚体切片结晶度(预聚体极限密度控制为1.38g/cm~3);根据最终产品需要选取不同的催化体系并通过调整 PTA/EG 配比控制预聚体中醚键含量;反应温度及反应时间是固相缩聚反应的主导影响因素,但控制反应中副产物的去除是破坏反应平衡、提高固相缩聚表观反应速率的重要手段。     

十四烷辅助下聚酯的固相缩聚

在200～240℃研究了聚对苯二甲酸乙二醇酯(PET)在十四烷辅助下的固相缩聚反应.结果表明,溶剂辅助下的固相缩聚(分散相固相缩聚)的反应速度较传统气相环境中的固相缩聚更快,最佳反应温度为230℃左右.随着反应温度的升高,分散相固相缩聚得到的PET切片的熔点和结晶度也相应提高.分散相固相缩聚前后PET切片的孔隙率并未发生明显变化.用苯酚处理之后的PET孔隙率增加,有利于小分子扩散,使缩聚反应速率加快.聚合物在十四烷中溶胀导致链活动性增强可能是分散相固相缩聚分子量提高的主要原因.     

尼龙66-6T共聚物的晶体结构与力学性能研究

以尼龙6T盐与尼龙66盐为原料,以己二酸为分子量调节剂,通过熔融缩聚法合成了不同尼龙6T盐含量的尼龙66-6T共聚物,然后通过固相缩聚法提高共聚物的相对分子质量,研究了共聚物的分子链主链结构、晶体结构和力学性能。结果表明:尼龙66-6T共聚物分子链中成功引入了苯环,部分己二酸的四亚甲基被对苯二甲酸的苯环替代;尼龙6T盐的加入没有改变尼龙66的晶型,共聚物的晶体结构仍为α晶型,但其结晶完善程度随尼龙6T盐含量的增加而降低;控制固相缩聚的温度为220℃、时间为6 h,各共聚物切片的数均相对分子质量基本处于同一水平;在共聚物的相对分子质量相近条件下,尼龙6T盐质量分数为0～20%时,随尼龙6T盐含量的增大,共聚物样条的拉伸强度和弯曲强度先增大后减小,缺口冲击强度逐步增加,最高可达到12.43 kJ/m~2。     

粉末PET固相缩聚的研究

系统地研究了粉末聚酯(PET)固相缩聚,得到了有效的干燥结晶条件:140℃干燥120 min,180℃再结晶45 min,切片含水率低于30μg／g;研究了反应温度,粉末粒径和N2流量对PET固相缩聚的影响,分析粉末固相缩聚存在N2流量阈值的机理。结果表明:反应温度越高,颗粒越小,固相缩聚反应速度越快;粉末 PET预聚体在一定温度下固相缩聚,存在N2流量阈值。在此流量下,达到该温度下的该粒径粉末的最大界面扩散速率和固相缩聚的最大反应速度。相同反应温度下,粉末粒径越小,阈值N2流量越大。     

尼龙66盐溶液预聚合动力学模型建立

盐溶液缩聚法是工业上生产尼龙66的主要方法,其预聚合工艺条件对产品质量有直接的影响。基于尼龙66盐离子内脱水与端氨基/端羧基缩聚反应活性的不同,建立了尼龙66盐溶液预聚合动力学模型,通过文献数据整定尼龙66盐离子内脱水反应、端氨基/端羧基可逆缩聚基元反应的表观活化能及指前因子,模型计算结果与文献数据吻合,误差较等活性模型小。以聚合物中尼龙66盐含量小于10-6 mol/g为基准,模型计算得到当水/尼龙66盐的物质的量比为6.23、反应温度为220℃时,预聚合反应时间需大于1.7 h。与预聚合反应时间为0.5 h的尼龙终聚物相比较,预聚合反应时间为2 h的尼龙66终聚物中的低聚物含量少、且其热性能和力学性能较优。建立的模型可用于指导盐溶液预聚合的工艺条件优化。     

PET固相缩聚反应动力学研究

建立了综合考虑 PET固相缩聚化学反应、小分子副产物物理扩散、大分子结晶三方面的 PET固相缩聚动力学模型 ,并用文献报道的实验测定数据验证该模型。运用该模型 ,研究了水、乙二醇、乙醛小分子副产物的含量与分布及其对固相缩聚的影响 ,从乙醛含量分布图可以得出 ,随着反应时间的延长 ,切片内各层乙醛含量降低不明显     

聚对苯二甲酸乙二酯(PET)固相缩聚动力学研究

本文以小型真空转鼓为反应装置,研究了PET的固相缩聚动力学,采用的PET预聚体是直接酯化工艺生产的未消光切片和酯交换工艺生产的不同厚度的薄膜。实验结果指出:在本实验条件下,PET预聚体的链增长速度在215℃处有一转折。动力学数据处理的结果表明:在固相缩聚期间PET的链增长按二级反应进行,而且与文献报道的动力学结果基本一致。对不同厚度的薄膜进行固相缩聚动力学研究,并用拉格朗日插值法外推到厚度为零,得到了消除样品层厚度影响的化学反应的表观动力学。实验结果还发现,左PET预聚体的固相缩聚期间,羧端基含量有所降低,醚键含量基本不变,并从反应机理上给予了说明。     

固相缩聚合成高分子量双酚A型聚碳酸酯

研究了以碳酸二苯酯和双酚A为原料,有机胺为催化剂,固相缩聚法合成高分子量双酚A型聚碳酸酯(BPA–PC)的新工艺。探究了预聚体粉料颗粒大小、缩聚温度、缩聚时间、预聚体分子量及官能团比例等工艺条件对产品性能的影响。结果表明,以四乙基氢氧化铵为催化剂,大于60目(小于250μm)的预聚体颗粒在210℃真空缩聚8 h,制得的缩聚体特性黏度较大。预聚体分子量越大,C6H5OH/OH官能团比例越接近1,缩聚物的分子量越大。在较佳工艺条件下,可得到数均分子量为52 572、分子量分布为1.830、熔点258℃、有一定结晶度的BPA–PC产品。     

PA6固相聚合——相对分子质量研究

本文对PA6固相聚合(SSP)过程中影响聚合产物相对分子质量(RMW)的因素进行了研究.结果表明:RMW随RMW调节剂用量增加稍微增加后再迅速减小;聚合时间增加,则PA6的RMW开始迅速增加,随后逐渐减慢.     

阴离子淤浆聚合尼龙6的性能研究

通过阴离子淤浆聚合方法,以氢氧化钠为催化剂、异氰酸酯作活化剂,以惰性脂肪烃为分散剂,在不同的反应时间和140～150℃温度下,制得了不同相对分子质量的尼龙6,最高相对粘度17．5。通过熔融纺丝,获得了可纺性良好的纤维,其断裂强度5．0～6．9 cN／dtex。X衍射测试分析表明,同阴离子本体聚合尼龙6(MC尼龙6)和高粘度尼龙6比较,阴离子淤浆聚合尼龙6在二次成型中更易于生成轫性较好的γ晶型,具有更高的冲击强度。     

Preparation of conducting nylon‐6 electrospun fiber webs by the in situ polymerization of polyaniline

For the preparation of conducting polyaniline (PANI)/nylon composites with high electrical conductivity as well as superior mechanical properties such as flexibility and lightness, PANI/nylon‐6 composite nanofiber webs were prepared via the electrospinning process with a nylon‐6/formic acid polymer solution, and then PANI on the surface of the nylon‐6 electrospun nanofiber webs was chemically polymerized. The electrical conductivity measurements showed that the conductivity of the PANI/nylon‐6 composite electrospun fiber webs was superior to that of PANI/nylon‐6 plain‐weave fabrics because of the high surface‐area/volume ratios. On the other hand, the volume conductivities of the PANI/nylon‐6 composite electrospun fiber webs increased from 0.5 to 1.5 S/cm as the diffusion time increased from 10 min to 4 h because of the even distribution of PANI in the electrospun fiber webs. However, the surface conductivities of the PANI/nylon‐6 composite electrospun fiber webs somewhat decreased from 0.22 to 0.14 S/cm as the diffusion time increased because of PANI contaminated with aniline monomers, aniline oligomers, and some alkyl chains, which served as electrical resistants. These results were confirmed with Fourier transform infrared, electron spectroscopy for chemical analysis, and morphology analysis. It was concluded that the diffusion time for the in situ polymerization of PANI in electrospun fiber webs was optimized at approximately 3 h. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 983–991, 2005     

尼龙6固相聚合中试试验研究

通过工厂中试实验研究,探讨了中试规模下聚合反应时间、反应温度、预聚体初始黏度等因素对尼龙6固相聚合的影响,确定了尼龙6固相增黏的工艺操作条件为:最佳温度175￣185℃,停留时间48h。     

Processing and properties of poly(p-phenylene benzobisthiazole)/nylon fibers

Composite fibers of poly(p-phenylene benzobisthiazole) (PBT) with nylons were spun from dilute acid solutions. The effects of wet-stretching, heat treatment time, tension, and temperature on the tensile properties are reported. Nylon 6,6 and nylon 6 at several molecular weights were studied. Moduli of 40 GPa and tensile strengths of 375 MPa were achieved for 30/70 PBT/nylon composites. Heat treatment of the nylon/PBT fibers at 160–225°C for 12–19 h increased the tensile modulus by 20–50% and the tensile strength by a smaller amount. At the same time, the intrinsic viscosity of the nylons increased as much as 100%, indicating the solid-state polymerization of the nylon. The largest tensile modulus attained is less than half the theoretical value predicted by a linear “rule of mixtures” as might be expected for an oriented molecular composite. Although differential scanning calorimetry shows a melting transition at temperatures 5–10°C higher than the pure nylons, the composite does not flow at temperatures above this transition. Sulfuric acid dissolves most of the nylon, but does not destroy the mechanical integrity of the fibers; differential scanning calorimetry indicates that the remaining fiber contains little or no nylon. The results are consistent with a microstructure consisting of a microfibrillar network of PBT, surrounded by a separate nylon phase.     

Solid-phase polymerization mechanism of poly(ethylene terephthalate) affected by gas flow velocity and particle size

Experimental studies on the solid-phase polymerization (SPP) of poly(ethylene terephthalate) (PET) for different particle sizes at temperatures of 190–220°C were carried out at different gas flow velocities. The SPP mechanism of PET changes under different operating conditions. At a given gas flow velocity, the SPP reaction mechanism for a large-sized sample changes from chemical reaction control to interior diffusion control with increasing temperature. At a given reaction temperature, the SPP reaction control mechanism for a small-sized sample changes from surface diffusion control to chemical reaction control with increasing gas flow velocity. At a given reaction temperature and gas flow velocity, the SPP reaction mechanism changes from interior diffusion control to surface diffusion control with decreasing particle size. The SPP reaction rate is not determined by a single control mechanism but by both diffusion and chemical reactions in the temperature range of 200–220°C. The primary control mechanism can be discerned based on the operating parameters.     

分散染料微胶囊的制备及其在锦纶染色浴中缓释性能研究

采用原位聚合法制备芯壁比1∶3、不同粒径及分布的系列分散染料微胶囊。采用激光粒径分析仪和SEM表征分散染料微胶囊的粒径分布及外形,通过DatacolorSF600PlusCT分光测色仪测定染色锦纶织物的表面色深度即K/S值表征微胶囊的缓释性能。实验结果表明:相同芯壁比,平均粒径越小、分布越窄的胶囊缓释性较强,pH值对胶囊缓释性影响较小。微胶囊对锦纶染色选择在130℃、40min、pH值在6￣7下染色,可达无助剂、无污染染色。     

MC尼龙6/TiO2原位纳米复合材料等温结晶动力学的研究

采用差示扫描量热法(DSC)研究了阴离子原位聚合法制备的铸型尼龙6(MC尼龙6)/TiO2纳米复合材料的等温结晶行为,并应用Avrami方程分析了MC尼龙6的等温结晶动力学过程.结果表明纳米TiO2对MC尼龙6基体具有异相成核作用,使其原位纳米复合材料结晶速率常数变大,半结晶时间变小.Hoffman成核结晶理论计算结果表明,原位纳米复合材料的Kg(与结晶温度无关而与成核方式有关的参数)大于MC尼龙6且随着纳米含量的增加而增加,说明纳米TiO2阻碍了MC尼龙6分子链的运动,同时尼龙6由晶核生长占主导地位逐渐向成核机制占主导地位转变.