聚乙烯醇缩甲乙醛工业生产中影响因素的探讨与控制

介绍聚乙烯醇缩甲乙醛生产的原理,影响产品质量的因素以及在生产中如何控制。     

聚乙烯醇缩甲乙醛制备条件的研究

研究了用聚乙烯醇（ＰＶＡ）、甲醛、乙醛为原料，在盐酸催化作用下，制备聚乙烯醇缩甲乙醛的各种影响因素，探索出了原料用量比、反应时间、反应温度、溶液ｐＨ值、ＰＶＡ浓度、加料方式等最佳反应条件。     

UV固化水性聚乙烯醇缩丁醛改性聚氨酯的合成及热稳定性研究

文章以异弗尔酮二异氰酸酯(IPDI)、2,2-二羟甲基丁酸(DMPA)、顺丁烯二酸酐、甲基丙烯酸羟乙酯(HEMA)为主要原料合成水溶性光固化聚乙烯醇缩丁醛改性聚氨酯。通过FT-IR、TGA等分析测试手段,研究了顺丁烯二酸酐改性的聚乙烯醇缩丁醛对水性丙烯酸聚氨酯热稳定性的影响。结果表明将聚乙烯醇缩丁醛和顺丁烯二酸酐引入到聚氨酯中,可显著提高其耐热性能,同时降低聚氨酯软硬段的微相分离。     

聚乙烯醇缩对硝基苯甲醛的合成与热稳定性

以聚乙烯醇（PVA）和对硝基苯甲醛为原料,二甲基亚砜为溶剂,对甲基苯磺酸为催化剂,采用均相工艺合成得到聚乙烯醇缩对硝基苯甲醛（PVPNB）。通过衰减全反射-傅里叶红外光谱（ATR-FTIR）、紫外可见光谱（UV-Vis）、核磁共振氢谱（¹H NMR）等测试手段对聚乙烯醇缩对硝基苯甲醛结构进行了表征。利用差示扫描量热仪（DSC）测定了聚乙烯醇缩对硝基苯甲醛的玻璃化温度（T_g）。采用差热分析（DTA）和热重分析（TGA）对聚乙烯醇缩对硝基苯甲醛热稳定性进行研究。DSC结果表明,聚乙烯醇缩对硝基苯甲醛的玻璃化温度为160 ℃。DTA和TGA结果表明,聚乙烯醇缩对硝基苯甲醛具有较好的热稳定性。     

聚乙烯醇缩甲乙醛制备条件的研究

研究了用聚乙烯醇，甲醛，乙醛为原料，在盐酸催化作用下，制备聚乙烯醇缩甲乙醛的各种影响因素，探索出了原料用量比，反应时间，反应温度，溶液ｐＨ、ＰＶＡ浓度、加料方式等最佳反应条件。     

改性聚乙烯醇缩丁醛胶粘剂的研制

以聚乙烯醇缩丁醛(PVB)为主料，乙醇和乙酸乙酯为溶剂，酚醛树脂为改性树脂，环氧树脂为增粘树脂，自制多元胺类固化剂，采用共混改性法，配制出无色透明、对环境友好、常温、接触压力固化的双组分胶粘剂。对于PVB的结构、PVB与改性树脂的配比、以及溶剂的选择对胶粘剂性能的影响进行了研究。     

聚乙烯醇缩丁醛-酚醛树脂-环氧树脂结构胶的研制

在氢氧化钠(NaOH)催化作用下,以苯酚和甲醛为主要原料,合成了甲阶PF(酚醛树脂),并测定了游离甲醛含量和收率;然后以PVB(聚乙烯醇缩丁醛)和甲阶PF为EP(环氧树脂)的柔韧改性剂、咪唑为固化剂,合成了三元共聚结构胶。研究结果表明:采用单因素试验法优选出制备甲阶PF的最佳工艺条件为n(F):n(P)=1.5:1、反应温度80℃和反应时间3 h;此时,甲阶PF的收率为92%,游离甲醛含量为1.4%。当m(PF):m(EP):m(PVB)=100:30:20、固化工艺为120℃/3 h时,制成的三元共聚结构胶用于铝板-铝板的粘接时,其剥离强度为15.72 N/cm、粘接强度为5.68 MPa。     

聚乙烯醇缩丁醛/酚醛树脂复合纤维的结构及性能

通过干法纺丝制备了聚乙烯醇缩丁醛/酚醛树脂(PVB/PF)复合纤维,研究了不同组分比例对该纤维的结构和性能的影响。结果表明,当PVB与PF质量比为5∶5时,PF在PVB中以尺寸为2～3μm的分散相存在。随着PF含量的增加,PVB/PF复合纤维的玻璃化转变温度(Tg)往高温方向偏移,且无论何种比例都表现为一个单一的Tg,这说明两者具有较好的相容性。红外光谱显示PVB与PF之间没有发生化学反应,但形成了氢键相互作用。热重分析发现PVB/PF复合纤维的热分解曲线综合了纯PVB和纯PF的特征。随着PF含量的增加,纤维的拉伸强度呈现出先上升后下降的趋势,当PVB与PF质量比为8∶2时,纤维的拉伸强度最高。     

腰果酚/聚乙烯醇改性酚醛树脂的制备

以腰果酚、聚乙烯醇作为苯酚与甲醛缩聚的改性剂,研究了腰果酚和聚乙烯醇的用量,催化剂类型和用量等对其性能的影响。结果表明:改性酚醛树脂的最佳条件为:苯酚、腰果酚、聚乙烯醇、甲醛的最佳摩尔比为0.85:0.32:0.02:1,最佳的催化剂为苯磺酸,用量为4.5%。     

Miscibility and hydrogen bonding in blends of poly(vinyl acetate) with phenolic resin

The miscibility of phenolic resin and poly(vinyl acetate) (PVAc) blends was investigated by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and solid state ¹³C nuclear magnetic resonance (NMR). This blend displays single glass transition temperature (T_g) over entire compositions indicating that this blend system is miscible in the amorphous phase due to the formation of hydrogen bonding between hydroxyl groups of phenolic resin and carbonyl groups of PVAc. Quantitative measurements on fraction of hydrogen-bonded carbonyl group using both ¹³C solid-state NMR and FT-IR analyses result in good agreement between these two spectroscopic techniques. According to the proton spin-lattice relaxation time in the rotating frame (T_1ρ^H), the phenolic/PVAc blend is intimately mixed on a scale less than 2-3 nm. Furthermore, the inter-association equilibrium constant and its related enthalpy of phenolic/PVAc blends were determined as a function of temperatures by infrared spectra based on the Painter-Coleman association model.     

氯化橡胶与氯醚树脂的合成与应用

介绍了氯化橡胶的应用及其合成方法,以及作为取代氯化橡胶应用于防腐材料中的氯醚树脂的主要合成方法。通过使用2种材料制成的漆的性能比较发现,氯醚树脂这种环保性更好的材料完全可以取代氯化橡胶,并且有更好的发展前景。     

Influences of individual and composed poly(vinyl alcohol) suspending agents on particle morphology of suspension poly(vinyl chloride) resin

Effects of individual and composed poly(vinyl alcohol) (PVA) suspending agents on the particle morphology of poly(vinyl chloride) (PVC) resins were investigated and discussed in the view of PVA absorption at the oil/water interface and interfacial behavior. It was shown that the percentage and surface coverage of PVA at the oil/water interface decreased with the increase of the degree of hydrolysis (DH) of PVA in the DH range of 70–98 mol %, while the interfacial tension of VC/PVA aqueous solution increased linearly with the increase of DH of PVA. PVC resin with more regular particle shape, increased agglomeration and fusion of primary particles, lower porosity and higher bulk density, was prepared by using PVA with a higher DH as a suspending agent. This was caused by the occurrence of drop coalescence at the very early stage of VC polymerization, the increase of particle shrinkage, and the lower colloidal protection to primary particles. It was also shown that the interfacial tension of VC/water in the presence of composed PVA suspending agents varied linearly with the weight composition of the composed PVA suspending agents. The particle properties of PVC resin prepared by using the composed PVC suspending agents were usually situated in between the properties of PVC resins prepared by using the corresponding individual PVA suspending agent. The particle morphology and properties of PVC resin could be controlled by the suitable choice of the composed PVA suspending agents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3848–3855, 2003     

Phase separation in styrenated polyester resin containing a poly(vinyl acetate) low-profile additive

Scanning electron microscopy has been used to observe morphology in styrenated polyester resins containing poly(vinyl acetate) (PVA). Resins containing 8% PVA form composite spherical particles which occupy 35 vol% of the total material. It is concluded that these particles consist of resin sub-inclusions embedded in the continuous matrix of polyester resin. Increasing the PVA content to 16% results in a phase inversion: PVA forms the matrix, and the resin is present as spherical particles. These observations are interpreted with the aid of a ternary diagram.     

The influence of poly(vinyl alcohol) suspending agents on suspension poly(vinyl chloride) morphology

The requirements for PVC suspension resin have changed considerably in the last few years, so much so that few companies have products on their ranges that are more than 4 or 5 years old. The suspending agent has a crucial influence on the morphology of the resin, so the changes in resin characteristics have largely been achieved by changes in the suspending agent systems. After a brief review of the mechanism of PVC suspension polymerisation, the properties of polymers made using PVOH suspending agents are related to changes in the latter. The effect of variations in PVAc degree of hydrolysis and viscosity are related to changes in surface tension. Methods of achieving higher porosity by using low hydrolysis co-suspending agents are described. It is shown that higher bulk densities can be achieved by delayed addition of the PVOH. Levels of conjugated unsaturation and copolymer distributions are also shown to have important influences.     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

甲基丙烯酸甲酯-丁二烯-苯乙烯树脂的合成及其对聚氯乙烯的改性

采用种子乳液接枝聚合技术合成了甲基丙烯酸甲酯(MMA)-丁二烯-苯乙烯树脂(MBS),考察了复合乳化剂浓度、CO2用量对丁苯胶乳粒径及其分布、胶乳稳定性的影响;研究了接枝单体滴加方式和接枝聚合反应温度对MBS体系稳定性和接枝效率的影响;讨论了MBS改性聚氯乙烯(PVC)的影响因素;提出了丁苯胶乳的碳酸化扩径附聚法和MBS胶乳的SO2凝聚新工艺。结果表明:在丁二烯/苯乙烯(质量比)为90/10、阴离子/非离子复合乳化剂浓度为35~40g/L、丁苯胶乳采用CO2附聚扩径、部分MMA预溶胀和其余MMA连续滴加的方式以及MBS胶乳SO2凝聚新工艺的条件下,所得MBS树脂粉料颗粒均匀,40~180目的颗粒质量分数达96%,堆积密度在0.4g/cm3以上;PVC/MBS(质量比为100/8)共混物的冲击强度达22.6kJ/m2。     

Dehydrochlorination of poly(vinyl chloride) modified with titanium dioxide/poly(ethylene oxide) based paint photocatalysts

The dehydrochlorination of poly(vinyl chloride) (PVC) film samples modified with titanium dioxide (TiO₂)/poly(ethylene oxide) (PEO) based paint photocatalysts [the addition of methyl linoleate (ML) or methyl oleate (MO)] was performed. After 24 h of UV photoirradiation, the sample with TiO₂/PEO showed that there existed a structure with the longest polyene length, whereas that with TiO₂/PEO/ML contained the most polyene structures. The chloroform‐soluble fraction of the sample with TiO₂/PEO contained a poly(vinyl alcohol) (PVA) structure instead of a polyene one and showed a novel method of PVA production via PVC photodegradation. The molecular weight curve of the fraction shifted slightly to a lower molecular weight compared to that without the photocatalyst; this showed that slight polymer chain scission occurred. The ¹H‐NMR and ¹³C‐NMR spectra showed that the content of PVA units was about 20%, and the PVA sequence was blocky. The fraction of the sample with TiO₂/PEO/ML contained the highest methyl group content; this showed that the branch degree was highest as was the polyene content. These highest contents were due to the existence of the grafted ML. Pyrolysis gas chromatography/mass spectroscopy measurements suggested that there existed more polyene and graft units in the chloroform‐insoluble fractions of the samples with TiO₂/PEO, TiO₂/PEO/ML, and TiO₂/PEO/MO, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40760.     

聚氯乙烯专用料的研究进展

介绍了国内外聚氯乙烯管材、电缆、医用专用料的研究进展。指出环保聚氯乙烯专用料是今后研究和开发的方向。     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl pyrrolidone)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMA) (designated iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(vinyl pyrrolidone) (PVP) primarily in chloroform to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PVP. The aPMMA/PVP and sPMMA/PVP blends were found to be miscible because all the prepared films showed composition-dependent glass-transition temperatures (T_g). The glass-transition temperatures of the aPMMA/PVP blends are equal to or lower than weight average and can be qualitatively described by the Gordon–Taylor equation. The glass-transition temperatures of the other miscible blends (i.e., sPMMA/PVP blends) are mostly higher than weight average and can be approximately fitted by the simplified Kwei equation. The iPMMA/PVP blends were found to be immiscible or partially miscible based on the observation of two glass-transition temperatures. The immiscibility is probably attributable to a stronger interaction among isotactic MMA segments because its ordination and molecular packing contribute to form a rigid domain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3190–3197, 2001