不同牌号氯化聚乙烯橡胶的结构与性能剖析

利用固体核磁共振波谱仪分析了5种牌号的氯化聚乙烯橡胶(CM 1035 X、CH 400、CH 420、CH 450和CM-1)的链结构和序列结构,探讨了其微观结构与性能之间的关系。结果表明,含氯质量分数最高的CH 420(42.0%)拥有最为均匀的氯原子分布,残余结晶少,硫化胶扯断伸长率高达742%,损耗因子最大,玻璃化转变温度最高;CM 1035 X的氯原子分布相对集中,无氯链段较长,因此其硫化胶扯断伸长率最低。氯含量过高和氯原子的集中分布均会降低氯化聚乙烯橡胶的热稳定性。     

橡胶型氯化聚乙烯结构研究

研究橡胶型氯化聚乙烯(CPE)的氯分布、相对分子质量及其分布、残余结晶度及流变性能。结果表明，橡胶型CPE的氯原子主要以单取代的形式存在于分子链上；4种橡胶型CPE的-↑Mw由大到小顺序为CPE6335，CPE6135，CPE6235，CPEl40B，-↑Mw越大，CPE的门尼粘度越小；橡胶型CPE的氯含量越大、氯原子分布越均匀，其残余结晶度越小；橡胶型CPE熔体为剪切变稀流体。     

核磁共振法测定聚磷酸铵聚合度

目前,国内外尚无高聚合度聚磷酸铵平均聚合度公认的权威性分析方法,国内测定聚磷酸铵平均聚合度的方法基本上是用端基滴定法,但该法不适宜测定高聚合度聚磷酸铵的平均聚合度.研究了用核磁共振测定高聚合度聚磷酸铵平均聚合度的方法.其原理是:聚磷酸铵的结构为非支链的长链状聚合物,利用核磁共振磷谱对聚磷酸铵磷原子个数进行测定,然后根据磷原子个数计算出聚磷酸铵的平均聚合度.可以测定从低聚到高聚的聚磷酸铵产品的平均聚合度,方法简便、快捷、准确,为高聚合度聚磷酸铵平均聚合度的分析提供了有力工具.     

基于HPCMS的功能性星型多臂共聚物的制备及应用

4-氯甲基苯乙烯(CMS)分子同时含有双键和卤原子,可通过自引发原子转移自由基聚合(ATRP)制备准三维球状超支化聚4-氯甲基苯乙烯(HPCMS)。HPCMS分子内带有大量苯亚甲基氯和苯次甲基氯基团,可继续作为引发剂,在HPCMS表面接枝聚合物链段,制得星型多臂共聚物。通过改变接枝链段的结构,可以得到一系列具有特殊结构和性能的共聚物。详细介绍了HPCMS的合成及支化度的测量,着重综述了星型多臂共聚物的合成及其在无机纳米粒子表面修饰、固体电解质、药物运载体等方面的应用进展,同时展望了星型多臂聚合物在热塑性弹性体方面的应用。     

基于HPCMS的功能性星型多臂共聚物的制备及应用

4-氯甲基苯乙烯(CMS)分子同时含有双键和卤原子,可通过自引发原子转移自由基聚合(ATRP)制备准三维球状超支化聚4-氯甲基苯乙烯(HPCMS)。HPCMS分子内带有大量苯亚甲基氯和苯次甲基氯基团,可继续作为引发剂,在HPCMS表面接枝聚合物链段,制得星型多臂共聚物。通过改变接枝链段的结构,可以得到一系列具有特殊结构和性能的共聚物。详细介绍了HPCMS的合成及支化度的测量,着重综述了星型多臂共聚物的合成及其在无机纳米粒子表面修饰、固体电解质、药物运载体等方面的应用进展,同时展望了星型多臂聚合物在热塑性弹性体方面的应用。     

高分子增韧剂对硝胺发射药抗冲击性能的影响

为了改善硝胺发射药的抗冲击性能,以一种硝胺发射药(RP5)药片为原料,分别采用低聚合度油状聚叠氮缩水甘油醚(GAP)和一种高聚合度聚氨酯为增韧剂,制备了不同增韧剂含量的硝胺发射药试样。采用落锤冲击试验机和摆锤冲击试验机分别测试了硝胺发射药试样的轴向和径向抗冲击强度。结果表明,径向方向,加入质量分数1%的GAP和质量分数3%的聚氨酯增韧剂均使硝胺发射药试样的抗冲击性能提升约20%;轴向方向,聚氨酯增韧的硝胺发射药试样在低温下的抗冲击性能更优。     

硝化甘油与高分子黏合剂混合体系相互作用的理论研究

运用MO-PM3方法计算了硝化甘油(NG)与高分子黏结剂聚乙二醇(PEG)、端羟基聚丁二烯(HTPB)、缩水甘油叠氮基聚醚(GAP)、3-叠氮甲基-3-甲基环氧丁烷聚合物(AMMO)和3,3-双(叠氮甲基)环氧丁烷聚合物(BAMO)的混合模型体系的几何结构(聚合度n=1,2,3,4),由色散能校正电子相关近似求得其分子间相互作用能(△E).结果表明,当n=4时,5个混合体系的相互作用能为-49～-60kJ/mol.除GAP和BAMO以外,当n值增大时,混合体系的相互作用能增加.混合体系中,两个子体系的原子与原子之间最短距离为0.270～0.340nm.     

超低聚合度PVC配方的优化

通过调整复合引发剂配比、链转移剂用量,筛选分散剂,选用复合热稳定剂等进一步优化超低聚合度PVC的配方,制得"鱼眼"数少、质量好的聚合度为500、600的PVC.     

低聚合度聚乙烯醇的制备

采用甲醇作溶剂,偶氮二异丁腈作引发剂,选用不同链转移剂,用溶液聚合法制备出低聚合度聚乙酸乙烯酯（PVAc）和聚乙烯醇（PVA）。研究了不同的单体与溶剂配比、链转移剂种类、用量及加入方式等因素对产物聚合度和单体转化率的影响。结果表明：以巯基醇为链转移剂,采用均匀滴加的方式,可制得平均聚合度分别为66～296,50—275的PVAc和PVA,单体转化率达70％～80％。     

端氯乙酰氧基原子转移自由基大分子引发剂的合成

用正丁基锂为引发剂，以苯、环己烷等为溶剂，加入苯乙烯或丁二烯聚合形成活性负离子，然后加入环氧乙烷封端形成烷氧基锂，最后加入氯乙酰氯进行氯乙酰化形成具有原子转移自由基引发基团的大分子引发剂。这些大分子引发剂引发原子转移自由基聚合合成的嵌段共聚物的结构已通过核磁共振谱图和红外光谱得到确认。     

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

The suspension polymerization of polyvinyl chloride (PVC) was carried out at two different constant temperature conditions (52.5°C and 57.5°C) and at two‐stage variable temperature conditions (52.5–57.5°C). The molecular weight and molecular weight distribution were characterized by gel permeation chromatography (GPC). The unstable chlorine content, total double bond content, and conjugated diene content were explored via phenol substitution, catalytic bromine addition, and ultraviolet–visible spectroscopy (UV–Vis). pH meter and thermogravimetric analyzer (TGA) were used for the determination of the thermal stability. According to the results, due to the gradual consumption of the impurities and the effect of the local high temperature in the early stage of polymerization, which caused more molecular chain‐transfer and more structural defects, a large number of oligomers generated. A rapid increase in the molecular weight could be found until the conversion was close to 23%. A lower temperature should be conducive to reducing the structural defects in molecular segments. Based on these observations, we applied two‐stage variable temperature polymerization and compared the PVC resin at a similar molecular weight at a constant temperature of 56°C. The PVC resin produced by the two‐stage variable temperature polymerization process obtained a similar Polydispersity index (PDI), reduced the unstable chlorine content by 15.11%, reduced the total double bond structure content by 8.81%, reduced the conjugated diene structure content by 13.86%, and increased the thermal stability time by 13.91%, thereby improving the thermal stability of the PVC resin. J. VINYL ADDIT. TECHNOL., 25:E80–E87, 2019. © 2018 Society of Plastics Engineers     

Fully quantitative carbon-13 NMR characterization of resol phenol-formaldehyde prepolymer resins

Different resol phenol-formaldehyde prepolymer resins have been synthesized with different Formaldehyde/Phenol (F/P) ratios or different catalysts and characterized by ¹³C NMR spectroscopy in solution. A fast quantitative measuring protocol is proposed based on the use of chromium(III)acetylacetonate as a relaxation agent. APT (attached proton test) and DEPT (distortionless enhancement by polarisation transfer) spectra were acquired to enable proper resonance assignments, especially in the regions with severe signal overlap. Equations are presented in which the methylene bridges (MB), the methylol groups (MG) and the dimethylene ether bridges (DMEB) of resol resins are quantitatively taken into account. Important structural factors determined quantitatively for resol prepolymer resins are the F/P ratio after reaction, the degree of polymerization (n), the number average molecular weight (M_n) and the content of free ortho and para positions.     

Core–shell type multi‐arm azide polymers based on hyperbranched copolyether as potential energetic materials in solid propellants

A series of novel multi‐arm azide copolymers (POGs) with the same hyperbranched poly[3‐ethyl‐3‐(hydroxymethyl)oxetane] core (PEHO‐c) and different content of linear glycidyl azide polymer shell (GAP‐s) have been synthesized by sequential cationic ring‐opening polymerization and azidation. Detailed structural information of these copolyethers was deduced from Fourier transform infrared, ¹H NMR and inverse gated decoupled ¹³C NMR spectroscopies, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, gel permeation chromatography and elemental analysis. The molecular weight of POG having GAP‐s and PEHO‐c with a molar ratio 14.95:1 (R_s/c) was around 31 000 g mol^?1, far above that of linear GAP (around 4000 g mol^?1). The apparent viscosity and glass transition temperature (?51 to ?23 °C) decreased first and then slightly increased with increasing molecular weight. Thermal analysis revealed that all the obtained POGs exhibited excellent resistance to thermal decomposition up to 220 °C. Moreover, the energetic properties, investigated using oxygen bomb calorimetric measurements, indicated that the enthalpy of formation of the POGs was higher than that of general linear GAP, but similar to that of branched GAP under reasonable R_s/c. The compatibilities of the POGs with common materials used in solid propellants were studied using differential scanning calorimetry and the results indicated that the POGs had good compatibility with these materials. © 2017 Society of Chemical Industry     

聚乙烯醇缩丁醛树脂分子量和热性能的测定

用凝胶渗透色谱(GPC)测定了高粘度PVB树脂(BH)和低粘度PVB树脂(BL)两种样品的平均分子量和分子量分布，并对所测结果进行了验证和讨论。对平均聚合度的验算表明，BH的平均聚合度与原料聚乙烯醇的平均聚合度相等，说明BH在缩醛化反应中大分子主链长度没有变化；而BL的平均聚合度却比原料聚乙烯醇的平均聚合度减小了62％，这是由于在制备BL时，在缩醛化之前对原料PVA用降解剂使其主链发生降解之故。用示差扫描量热法(DSC)对上述两种样品进行了热性能分析，分析结果表明，PVB中乙烯醇链节(VOH)的含量增加5．1l％(质量分数)，可使PVB的熔点增高9℃，PVB的结晶度增大1．4倍；结晶度增大使PVB的宏观物理性能(如溶解度等)发生显著的变化。     

Preparation and mechanical properties of poly(vinyl chloride)/bamboo flour composites with a novel block copolymer as a coupling agent

To improve the interfacial adhesion between poly(vinyl chloride) (PVC) and bamboo flour in PVC/bamboo flour composites, a novel coupling agent, poly(styrene‐co‐maleic anhydride)‐block‐poly(styrene‐co‐acrylonitrile) {P[(SMA)‐b‐(SAN)]}, was synthesized through living free‐radical polymerization in a one‐pot reaction. P[(SMA)‐b‐(SAN)] was synthesized by a nitroxide‐mediated polymerization technique in the presence of 2,2,6,6‐tetramethylpiperidin‐l‐oxyl with azobisisobutyronitrile. The conversion of maleic anhydride (>99%) and styrene (>65%) was relatively high and yielded P[(SMA)‐b‐(SAN)] with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight <1.38). PVC was blended with bamboo flours in the presence of the synthesized coupling agent with a two‐roll mill. P[(SMA)‐b‐(SAN)] was added to the PVC matrix at a concentration of 55 or 20 wt %. As the content of P[(SMA)‐b‐(SAN)] in the wood–polymer composite increased, improved morphological and mechanical behaviors were observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of novel gold‐coated syndiotactic poly(vinyl alcohol) microfibrils by sputtering

To prepare a syndiotactic poly(vinyl alcohol) (PVA)/gold complex for various biomedical applications, ultrahigh‐molecular‐weight syndiotactic PVA microfibrils were directly prepared by the saponification of poly(vinyl pivalate) that was obtained through bulk polymerization of vinyl pivalate at 30°C. PVA microfibrils with a number‐average degree of polymerization, syndiotactic diad content, and degree of saponification of 14,300, 61.7%, and 99.9%, respectively, were gold‐coated by sputtering at 140 and 150 W (Watt) for 1, 2, and 3 min, respectively. A weight gain of up to 7% by the gold atoms for the PVA microfibrils treated at 150 W for 3 min was found. Morphological changes at the surface were observed by a microscopic method. A mechanism of gold coating on PVA microfibrils is suggested. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2369–2372, 2003     

Synthesis and characterization of energetic GAP‐b‐PAEMA block copolymer

Energetic block copolymer of polyglycidylazide‐b‐poly (azidoethyl methacrylate) (GAP‐b‐PAEMA) was synthesized and characterized. Macroinitiator PECH‐Br prepared via the reaction of 2‐bromoisobutyryl bromide with hydroxyl‐terminated polyepichlorohydrin (PECH‐OH) was used to initiate the atom transfer radical polymerization (ATRP) of chloroethyl methacrylate (CEMA). After azidation of the resulting copolymer, energetic copolymer GAP‐b‐PAEMA was obtained. Increase in the molecular weight determined by gel permeation chromatograph (GPC) is in agreement with the formation of block copolymer. Fourier transform infrared spectroscopy (FTIR) shows that the chlorine groups in the block copolymer can be substituted by azide group easily. Thermogravimetric analysis (TGA) shows that degradation of GAP‐b‐PAEMA involves two steps: the instantaneous decomposition of the azide groups followed by progressive scission of the polymer backbone. From differential scanning calorimetry (DSC) analysis, the GAP‐b‐PAEMA copolymer exhibits two glass transition temperatures (T_g) at ?18 and 36°C, suggesting that the synthesized copolymer is a thermoplastic elastomer. This research provides a new method for the synthesis of energetic polymer. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Über die chlorierung von poly-2,6-dimethyl-1,4-phenylenäther

Poly(2,6-dimethyl-1,4-phenylene ether), prepared by oxidative coupling of purified 2,6-dimethylphenol, was chlorinated with FeCl₃ or AlCl₃ as catalysts (I) and under UV -radiation (II). By (I) polymers with up to a maximum content of 36% Cl (disubstituted structural units) and by (II) polymers with up to a maximum 55% Cl (tetrasubstituted structural units) were obtained. During the chlorination a strong chain degradation takes place, which is recognizable by decrease in viscosity number [η] and by loss of mechanical strength and tenacity of the material. The proof of the degradation was furnished by dechlorination with LiAlH₄, which caused no increase in [η] and by molecular weight determination via sedimentation (Dr. E. Schuch, BASF). The degree of polymerization decreased from P? = 620 to P? = 89 by the 30% chlorinated polymer and to P? = 62 by the 51% chlorinated product. It was shown that the scission of the poly(phenylene ether) chains is not caused by HCl but by chlorine.     

Synthesis and characterization of comb‐like polymer PVC–poly(ethylene oxide)

A new series of amphiphilic graft‐copolymers, composed of poly(vinyl chloride) (PVC) backbones and poly(ethylene oxide) side chains, was synthesized by chemical modification of PVC. The synthesis was based on the reaction between chlorine in PVC (polymerization degree 700) and sodium salt of polyethylene glycol (PEG). PEGs with molecular weights of 200 and 600 were used. The graft polymers were characterized by IR and gel permeation chromatography and the molecular parameters such as the average numbers of grafting chains on the PVC backbones were calculated as well as the grafting percent. The molecular weights of PEG were found to influence the rate of the grafting reaction and the final degree of conversion. The maximum grafting percentage of the resulted polymers after the purification was ca. 34%, regardless of the molecular weight of PEG. No gel was observed in the PVC‐g‐PEOs, in spite of the average numbers of grafting chains up to 32. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 475–479, 2000     

Semicontinuous emulsion polymerization of vinyl acetate: Effect of ethoxylation degree of nonionic emulsifiers

Poly(vinyl acetate) latices were prepared in the presence of an ammonium persulfate initiator, 10–50 mol of an ethoxylated nonylphenol nonionic emulsifier, and a poly(vinyl alcohol) colloid stabilizer by applying semicontinuous emulsion polymerization (delayed monomer and initiator addition process) in a laboratory scale similar to industrial practice. Two approaches were applied: the molar concentration of the nonionic emulsifier was kept constant and the weight ratios in the polymerization recipe varied or the weight ratios were kept constant. The effects of the change in the ethoxylation degree of the emulsifier to the final latex viscosity, average polymer molecular weight, polymer grafting degree, surface tension of the latex, and the surface free energy of the dried films were investigated. It was determined that the resultant latex viscosity decreases and the viscosity‐average polymer molecular weight increases with increase of the nonionic emulsifier ethoxylation degree. The increase of the ethoxylation degree does not seriously affect the surface tension of the resultant latex or the surface free energy of the dried poly(vinyl acetate) films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 844–851, 2002