聚甲醛/聚氧化乙烯共混体系流变行为的研究

将聚甲醛(POM)与聚氧化乙烯(PEO)熔融共混,制备改性聚甲醛,用熔体指数仪和高压毛细管流变仪研究了POM、PEO及POM/PEO共混体系的流变性能.试验结果表明随PEO含量增加,共混体系熔体指数(MFI)减小.POM表观黏度对温度的敏感性大于PEO,对剪切速率的敏感性小于PEO.随PEO含量增加,共混体系的温度敏感性下降,剪切敏感性增大.在热塑加工中,可通过改变剪切速率,调节熔体黏度,从而控制共混物形态结构.     

聚氧化乙烯合成工艺研究

氧化乙烯（EO）开环聚合而成的线型高聚物,是一种具结晶性和热塑性的水溶性聚合物。其相对分子质量在200—20000者称为聚乙二醇（PEG）,相对分子质量在十万以上者称为聚氧化乙烯（PEO）。PEO为白色粉末,软化点为65—67℃,脆化点为-55℃,具有水溶性好、毒性低、易加工成型等特点。本工作对采用氨钙体系催化剂时,合成PEO的工艺条件如催化剂用量、反应温度、反应时间等与PEO相对分子质量和聚合收率的关系进行了考察。     

环氧改性水溶性硅油的合成

在氯铂酸催化下，通过低含氢硅油与不饱和缩水甘油醚、聚氧乙烯烯丙醚的硅氢加成反应，制得环氧改性水溶性硅油；采用化学滴定法测定未反应活性氢的质量分数，从而确定含氢硅油的转化率；在合成过程中采用甲苯作溶剂、正丙醇作封闭剂，可避免在中和反应后发生交联，有利于保证产品的稳定性。最佳反应条件为：催化剂用量为单体质量分数的0．0189％；不饱和聚醚与含氢硅油的量之比为1．1：1．0、反应时间4h、反应温度85℃；在此条件下，含氢硅油的转化率为97．1％。     

PLA/PEO共混物的结晶行为研究

共沉积技术制备了聚乳酸(PLA)/聚氧化乙烯(PEO)共混物,通过DMA和相差显微镜考察了共混物的相行为。用DSC研究了PLA/PEO共混物的结晶形貌及其动力学,由于部分相容的熔融态PEO提高了PLA分子链的运动能力,导致显著促进了PLA的结晶速率;结合偏光显微镜(POM)观察分析,结晶速率的提高源于结晶生长速率的促进,而且在低的结晶温度时的结晶速率的增加更为明显。     

聚氧乙烯山梨醇脂肪酸酯与脂质膜间相互作用的研究

研究了表面活性剂聚氧乙烯山梨醇脂肪酸酯(吐温-80)与脂质膜间的相互作用,运用浊度测定、DSC、1HNMR等分析手段验证了脂质膜的立体稳定结构。结果表明:聚氧乙烯山梨醇脂肪酸酯在水相与脂质相间分配达到饱和时的质量分数为w(聚氧乙烯山梨醇脂肪酸酯)=1 3%,与脂质膜开始增溶成混合胶团时的质量分数为w(聚氧乙烯山梨醇脂肪酸酯)=2 6%。当Re〔表示吐温-80与卵磷脂的摩尔比值,即n(吐温-80)/n(卵磷脂)〕<0 5时,表面活性剂单体在溶液和脂质双层膜中分配,溶液中表面活性剂单体和囊泡并存,脂质双层囊泡膨胀,粒径逐渐增大,形成一个肿胀的脂质囊泡;当0 5相似文献   

聚氧化乙烯研究开发进展及展望

聚氧化乙烯是一类重要的有机聚合物,本文综述了聚氧化乙烯的物理和化学性质,分析了聚氧化乙烯的三种催化聚合体系及其应用,展望了聚氧化乙烯的发展趋势.     

水溶性氨基改性醇酸树脂的制备

以亚麻油脂肪酸、三羟甲基丙烷、苯酐、偏苯三酸酐、顺酐以及三聚氰胺树脂为主要原料,采用熔融脂肪酸法制备了水溶性氨基改性醇酸树脂,通过对醇酸树脂的水溶性、黏度、稳定性以及漆膜硬度和附着力进行测试及分析,确定了水溶性醇酸树脂的配方。     

聚氧乙烯脂肪酸乙醇酰胺磺基琥珀酸单酯二钠的表面活性

研究了聚氧乙烯脂肪酸乙醇酰胺磺基琥珀酸单酯二钠的表面活性。结果表明,随氧乙烯聚合数或脂肪酸碳原子数的增加,临界胶束浓度减小而最小表面张力增大,润湿力和起泡力都下降。泡沫稳定性都较高且随氧乙烯聚合数的增加变化不显著,随脂肪酸碳原子数的增加趋于增强。     

水溶性导电聚合物的合成与表征

采用溶液聚合法合成了具有水溶性的导电聚合物——聚(N-苯磺酸基苯胺),并用红外光谱、紫外光谱和热重分析等对该聚合物进行了表征。研究表明,聚(N-苯磺酸基苯胺)能完全溶解于水、氨水和盐酸中。盐酸掺杂的聚(N-苯磺酸基苯胺)的电导率为6.0×10-4S cm-1。热重分析表明,聚(N-苯磺酸基苯胺)的热分解过程分为四个阶段。     

水溶性氨基聚硅氧烷织物柔软剂的研究

以氨基分布均匀的反应性氨乙基氨丙基硅油和聚氧乙烯甲基缩水甘油醚为原料,通过开环反应,合成了可用于织物柔软整理的水溶性氨基聚硅氧烷,整理后的织物具有柔软的手感、较好的白度和吸水性。确定了最佳合成条件:聚氧乙烯甲基缩水甘油醚与反应性氨乙基氨丙基硅油摩尔比为7.2,w(异丙醇)=1(相对于聚氧乙烯甲基缩水甘油醚和氨基硅油的总质量),反应温度为80℃,反应时间为5h。     

Effect of water on the solubility and diffusivity of hydrocarbons in polyethylene

There are indications in the literature that the devolatilization of some polymers, particularly polyethylene, can be enhanced by the addition of water, generally in the form of steam. In this study three different experimental methods were used with three different solvent–polyethylene systems to evaluate this effect. The results indicated that no measureable differences were found in either the solubility or the diffusivity of the systems between the dry or wet polymer samples. POLYM. ENG. SCI., 55:1459–1462, 2015. © 2015 Society of Plastics Engineers     

氧化铋光催化剂改性研究

通过对实验室制备的氧化铋光催化剂减小催化剂粒径、表面螯合、金属离子掺杂、催化剂固载等方法进行改性研究,表明均能提高氧化铋的催化活性。     

壳聚糖/聚氧化乙烯静电纺丝工艺研究

采用聚氧化乙烯(PEO)与壳聚糖(CS)混合配制PEO/CS的稀醋酸溶液,进行静电纺丝,制得PEO/CS纳米纤维毡.考察了静电纺丝工艺条件对纤维直径和形貌的影响,并对PEO/CS纳米纤维毡进行了形态、结构、结晶性能、亲水性能等方面的表征.结果表明:PEO/CS纳米纤维毡的静电纺丝的最佳参数值为PEO/CS质量比为70/...     

Physical wrapping of reduced graphene oxide sheets by polyethylene wax and its modification on the mechanical properties of polyethylene

A facile method to encapsulate the reduced graphene oxide (RGO) sheets physically with polyethylene (PE) wax was developed. The graphene oxide sheets were first wrapped with polyethylene wax, and reduced by hydrazine hydrate. The structure of the wrapped RGO was confirmed by means of Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and Raman spectroscopy. The PE wax‐wrapped RGO sheets were melt blended with PE to prepare PE/RGO nanocomposites. Transmission electron microscopy and XRD studies showed that this method could provide uniform dispersion of RGO sheets in the PE matrix. Scanning electron microscopy and Raman spectroscopy indicated that there was a strong interfacial interaction between the PE wax‐wrapped RGO sheets and PE matrix. Addition of 1 wt % RGO sheets in PE matrix led to a 48% increment in the yield stress and 118% increment in the Young's modulus, respectively. However, the elongation at break decreased with increasing RGO sheets loading content. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Shear modification of polyethylene

Polymers like LDPE can be modified by applying a shearing process for an extended period. As a result the melt elasticity is reduced, as evidenced by the decrease in extrudate (die) swell at the exit of a capillary and onset of melt fracture. Melt viscosity was also slightly reduced; melt flow index (measured in short capillary) is highly increased. At the same time, melt density rises. All these parameters vary mostly for LDPE grades that exhibit the highest degree of long-chain branching. It was confirmed that the intrinsic viscosisty of the polymer samples was essentially unaffected, so that chain scission may be ruled out. Moreover, the process itself is shown to be reversible as the initial parameters were recovered by special treatment, due to heating or solvation. The mechanism of shear modification is believed to consist of disentanglement of temporary couplings betwen long branches. The practical utilization of this process will be pursued, as well as the scientific understanding of structuring entangled branched chains.     

黏度法研究两性聚丙烯酰胺的水溶性

利用水溶液聚合合成了不同组成的两性聚丙烯酰胺(AM/MADQUAT/NaAMPS),对其溶液黏度受NaCl溶液浓度的影响进行了研究。结果表明,净电荷含量较大的两性聚丙烯酰胺溶液,在低NaCl浓度下特性黏度大、溶解性好;而净电荷含量较小的两性聚丙烯酰胺溶液(特别是带有高电荷密度时),在较高的NaCl浓度下,聚合物溶液特性黏度大、溶解性好,反聚电解质效应明显。     

PVAc耐水性能改性研究

以过硫酸钠作为引发剂,以甲基丙烯酸甲酯(MMA)、叔碳酸乙烯酯(VeoVa10)和丙烯酸丁酯(BA)作为醋酸乙烯酯(VAc)的共聚改性单体,采用先预乳化后半连续滴加法制备改性聚醋酸乙烯酯(PVAc)乳液.探讨了搅拌速率、共聚单体配比、聚乙烯醇(PVA)和引发剂含量等对改性PVAc乳液性能的影响.结果表明:当m(VAc ...     

丁腈橡胶/聚氧乙烯共混体系对聚氧乙烯结晶性能的影响

通过溶剂浇注法制备了丁腈橡胶/聚氧乙烯(NBR/PEO)共混物,通过接触角测试、傅里叶变换红外光谱分析和差示扫描量热分析,研究了NBR和PEO相互作用对PEO结晶性能的影响。结果表明,NBR/PEO共混物的表面能和附着功分别为8.80 mJ/m2和56.90 mJ/m2,两者之间具有一定的相容性;NBR中的腈基和PEO中的醚基之间并没有相互作用,两者之间具有一定的相容性,是由非极性部分贡献;NBR/PEO共混体系中随着PEO含量的减少,PEO分子链采取旁式构象的结晶结构增多,并使PEO的结晶度和结晶熔融温度明显降低,在PEO含量为5份时,NBR/PEO共混体系中PEO结晶度和结晶熔融温度分别下降80%和10.5℃,NBR的加入明显抑制了PEO的结晶。     

Modeling solubility of gases in semicrystalline polyethylene

An absorption model of gases in semicrystalline polymer was built that was based on the activity coefficient theory in polymer solution and associated with crystallinity dependent on temperature. The solubility of ethylene, isopentane, and n‐hexane in three types of polyethylene (PE) were obtained by the use of a pressure‐decay method at temperatures of 333–363 K and pressures of up to 2 MPa, 80–300 KPa, and 19–100 KPa, respectively. Experimental data from three gases in each PE sample were used for the single‐parameter fitting, and fitting error was within about 12%. It was found that a single parameter was merely dependent on the properties of PE used. It was shown that, unlike with the Flory–Huggins model and the UNIFAC–M‐H method, correlation between the crystallinity of the semicrystalline polymer and temperature had to be taken into account in order for the solubility data of alkane, olefin, and aromatic hydrocarbons in polyethylene to fit well, especially in the temperature range near the melting point of the polymer. The four free‐energy contributions to the total gas activity were experimentally determined to be about 47%–60% combined, the free‐volume contribution about 12%–25%, and the elastic effect about 22%–35%, but the interactional contribution was zero. The contributions changed with the size of the gas molecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1737–1744, 2007     

烟酸在水中的溶解度及介稳性质的研究

介稳区宽度(MSZW)是结晶过程设计的重要参数,为了得到高纯度大颗粒的烟酸晶体,应将结晶条件控制在介稳区内。测定烟酸在293.15—323.15 K下的溶解度,并用Apelblet经验方程关联,与实验值相比有较好的拟合效果,相对偏差在0.66%以下,平均偏差为0.27%;以溶解度数据为基础,计算了烟酸的溶解热力学参数。另外,通过聚焦光速反射测量(FBRM)技术测定烟酸的介稳区宽度,研究了降温速率、搅拌速率和晶种加入量对介稳区宽度的影响,研究发现,较小的降温速率、较大的搅拌速率以及加入晶种都会使介稳区宽度变窄;适当增大晶种数目,可以有效调节介稳区。溶解度及介稳区的测定,为生产过程工艺放大以及结晶器的设计提供数据支撑。