低聚合度低醇解度聚乙烯醇制备工艺条件的研究

采用单因素法研究了单体浓度,引发剂的用量对聚合度,碱摩尔比及醇解温度对醇解度的影响。     

低聚合度部分醇解型聚乙烯醇树脂的应用开发

综述了低聚合度、部分醇解型聚乙烯醇(PVA-0588)在纺织业、长纤维经纱上浆、印刷业、医药业、建筑业以及其他领域的应用开发,并简介PVA-0588的制法和主要特性。     

低聚合度、低醇解度PVA的中间产品PVAc聚合度的研究

本文研究了聚醋酸乙烯聚合度的调节方法,重点探讨了制取PVC悬浮聚合用分散剂——低聚合度、低醇解度PVA的中间产品低聚合度聚醋酸乙烯的方法。     

S-500型低聚合度PVC树脂的开发研究

研究了S-500型低聚合度PVC树脂的合成技术,确定了使用链转移剂合成S-500型PVC树脂的聚合配方和工艺条件。结果表明:S-500型PVC树脂相对分子质量分布集中,颗粒规整度好,粒度分布集中,熔体流动速率较高,加工塑化性能良好。     

超低聚合度的PVC树脂及其生产方法

专利申请号:CN200910167753.0公开号:CN101665548申请日:2009.09.25公开日:2010.03.10申请人:四川金路集团股份有限公司本发明公开了一种超低聚合度的PVC树脂及其生产方法。本发明采用聚合方法进行聚合反应,反应温度60～64℃,反应压力小于1.0MPa,在聚合反应开     

高聚合度聚乙烯醇的制备研究

制备高聚合度聚乙烯醇的方法有乳液聚合法,辐射聚合法,超低温复合乳液聚合法等。本文采用低温乳液聚合法制备聚合度在2000以上的聚乙烯醇,此方法具有容易实现工业化,聚合率高的特点。     

低温法高聚合度聚氯乙烯合度度的调节

根据氯乙烯聚合机理，由低温法合成高聚合度聚氯乙烯实验数据，拟合得到平均聚合度与温度、引发剂浓度的关系式：＾－Ｐ１／｛１３４００ｅｘｐ（－４５０００／ＲＴ）＋１００ｅｘｐ（－２０５００／ＲＴ）［Ｉ］／［Ｍ］｝，向单体、引发剂链边转移常数与温度的关系式：ＣＭ＝１３４００ｅｘｐ（－４５０００／ＲＴ），Ｃ１＝１００ｅｘｐ（－２０５００ＲＴ）。     

高聚合度聚乙烯醇的制备

采用醋酸乙烯酯为单体,以OP-10和十二烷基硫酸钠为复配乳化剂,偶氮二脒基丙烷盐酸盐为引发剂,通过正交实验研究了乳液聚合法制备高聚合度聚醋酸乙烯酯的最佳工艺条件.通过单因素实验验证了最佳工艺条件的可靠性,并分析了乳化剂用量、引发剂用量和反应温度对醋酸乙烯酯平均聚合度的影响规律.在最佳工艺条件下制得了聚合度为5 100的聚醋酸乙烯酯,经醇解得到了聚合度为4 800的聚乙烯醇.     

高聚合度PVAc醇解工艺研究

高聚合度的聚醋酸乙烯酯醇解制备聚乙烯醇,由于其相对分子质量较大,所以研究其醇解工艺显得尤为必要.就影响醇解工艺的因素,如醇解温度、醇解时间、催化剂浓度等进行了探讨,得出了高聚合度PVAc醇解最佳工艺.     

Ultra-low degree of polymerization polyvinyl alcohol products prepared by oxidative chain scission: Method and mechanism

In this paper, the high value-added (ultra-low degree of polymerization [ULDP]) polyvinyl alcohol (PVA) product was successfully prepared by oxidative chain scission method with sodium hypochlorite as an oxidant. When the molar ratio of PVA to NaClO is not less than 1:1.8, the reaction is stirred for several hours (≥2 h) at a temperature not exceeding 50°C. After precipitation and washing in methanol, PVA with polymerization degree of 38–150 can be obtained after drying. The infrared spectrum (IR) and nuclear magnetic hydrogen spectrum (¹H-NMR) test proved that the product obtained by this method is indeed PVA. The results of ¹H-NMR also showed that the chain broken has no selectivity and the stereoregularity of hydroxyl group did not change significantly. Through radical quenching experiment and electron paramagnetic resonance (EPR) analysis, it is proved that OCl⁻ is the main active oxide, ·Cl makes the oxidative chain scission process can be realized quickly, and ·OH is an indispensable factor for obtaining ULDP PVA. Under the combined action of these three, high value-added PVA with ULDP was successfully prepared. Additionally, the sodium hypochlorite oxidized the ·OH captured by 5,5-dimethyl-1-pyrroline-n-oxide (DMPO-OH) to 2-hydroxy-5,s-dimethyl-1-pyrroline-N-oxide (HDMPO-OH) in an alkaline environment.     

The effect of degree of polymerization on the structure and properties of polyvinyl alcohol fibers with high strength and high modulus

Polyvinyl alcohol (PVA) fibers were prepared using PVA with different degree of polymerization (DP) under the same wet spinning process. The effect of the DP of PVA on the structures and properties of PVA and PVA fibers were studied by using nuclear magnetic resonance hydrogen spectroscopy (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA), and environmental scanning electron microscope (ESEM). The results showed that DP had little effect on the crystallinity and tacticity of PVA, but had a positive effect on melting temperature, and initial decomposition temperature of PVAs. The hot drawing ratio determined by the spinning process where the PVA fibers could be continuously collected without breaking. The drawing ratio was decreased with an increase of DP, resulting in an increase of the final fiber diameter. The PVA fibers with medium DP and medium size demonstrated high strength and high modulus, but relatively low breaking elongation. It suggested that high DP of PVA was not a guarantee of high strength and high modulus PVA fibers, but rather a primary structure factor. The fiber performance was determined by a comprehensive effect combining a variety of factors including polymer properties and spinning conditions. It provided a guideline for PVA fiber manufacture that the PVAs with different DP require different spinning processes to obtain optimal fiber performance.     

80%醇解度聚乙烯醇的制备工艺

用乙醇为溶剂醇解聚醋酸乙酯(PVAc)制备80%醇解度的聚乙烯醇(PVA),采用正交实验法得到最佳制备工艺,用红外光谱对PVA进行了表征。结果表明:红外光谱表征PVA的特征波数为3 378 cm-1。在含碱量0.38%,含水量1.2%,加酸时间50 m in的最佳醇解条件下,可得到醇解度为80.6%的PVA,其质量指标达到日本进口分散剂KH-20要求。     

The role of polyvinyl alcohol in emulsion polymerization

Emulsion polymerization of styrene (St) and vinyl acetate (VAc) in the presence of conventional polyvinyl alcohol (PVA), PVA modified with a terminal alkyl group or PVA modified with a terminal thiol group (HS-PVA) was compared. Whereas stable PVAc latexes were obtained, a stable PSt latex was obtained only in the case of HS-PVA. From the adsorption isotherms of these PVAs on the surface of PVAc and PSt latex particles, as well as the grafting efficiencies of VAc and St onto HS-PVA in relation to the stability of the polymerization process, the role of PVA in the emulsion polymerization was discussed.     

纺丝原料对高强高模聚乙烯醇纤维结构性能的影响

研究了纺丝原料聚合度、转化率对聚乙烯醇(PVA)纤维高强高模化的影响。结果表明:高聚合度有利于减少端基缺陷,提高纤维性能;低转化率PVA相对高转化率PVA具有高的聚合度和线性程度,所得纤维力学性能更高。同时发现,低转化率原料纺得纤维在高倍拉伸后有强度模量较高的横纹丝产生,因此适合制备高强高模纤维。     

高性能聚乙烯醇纤维的研究进展

综述了高性能聚乙烯醇(PVA)纤维的研究进展;介绍了超高相对分子质量和高立构规整度的PVA 制备方法;详述了凝胶纺丝制备高性能PVA纤维的工艺及其影响因素:纤维结构、拉伸工艺、溶剂、凝固剂种类、凝固浴温度等。展望了高性能PVA纤维的发展动向和应用前景;指出高聚合度、高间规度PVA纤维是其研究方向。     

低聚合度PVC树脂的研制

通过选择合适的引发体系、分散体系、耐热终止剂,调整链转移剂用量,在10 L聚合釜中制备出低聚合度(700)PVC树脂。     

醋酸乙烯酯乳液与聚乙烯醇接枝反应的研究

研究了以聚乙烯醇为保护胶体的醋酸乙烯乳液聚合中,作为保护胶体的聚乙烯醇与醋酸乙烯的接枝反应。发现聚乙烯醇的接枝主要发生在初期,而醋酸乙烯的接枝链一直增长到胶粒沉析;另外,保护胶体黏度对接枝率也有影响,黏度越大醋酸乙烯的接枝率越低。