PAE与丙烯酰胺接枝共聚改性的研究

利用溶液聚合的方法，使丙烯酰胺单体与不饱和聚酰胺多胺环氧氯丙烷树脂接枝共聚。在实验过程中，运用单体因素分析的方法，讨论了反应时间、引发剂用量、聚合单体丙烯酰胺的用量等主要因素对接枝共聚反应的影响。接枝后的聚丙烯酰胺树脂除了具有良好的湿拉伸强度性能外，还可以大幅度地提高纸张的干拉伸强度。     

紫外辐射接枝改性UHMWPE纤维表面的研究

采用紫外辐射接枝方法对超高相对分子质量聚乙烯(UHMWPE)纤维表面进行改性。探讨了单体种类及浓度、引发剂、抗氧剂、接枝方法等对UHMWPE纤维表面处理效果的影响,测试了以其作为增强材料的复合材料的层间剪切强度。结果表明:在有氧开放体系下,气相接枝效果好于液相接枝;丙烯酰胺单体的接枝效果优于其它单体;接枝率随接枝单体浓度和接枝时间的增加而增加。采用丙烯酰胺为接枝单体,在光强度为86μW/cm~2条件下,对UHMWPE纤维进行紫外辐射接枝改性,按照一定铺层方式制备的环氧基复合材料的层间剪切强度从未处理的14.59MPa提高到17.36MPa。     

乳液接枝聚合的反应控制对ABS树脂性能的影响

采用种子乳液聚合方法合成PB-g-SAN(ABS)接枝共聚物,与苯乙烯丙烯腈共聚物(SAN)熔融共混制备ABS树脂。主要研究了在聚丁二烯橡胶粒子(PB)上接枝苯乙烯(St)和丙烯腈(AN)单体制备ABS接枝共聚物过程中,单体的加料时间和预溶胀过程的控制对单体的接枝效果、ABS橡胶粒子的形态以及最终ABS树脂性能的影响。实验结果表明:与一次投料工艺相比,在接枝过程中连续进料方式有助于提高接枝效率,且单体连续加料时间适当缩短有助于提高ABS树脂的冲击强度;单体预溶胀过程会降低接枝效率,并且容易使St单体进入PB相形成内包容结构,接枝过程中保持预溶胀合适的单体量有助于提高ABS树脂的冲击强度。     

ACR乳胶特性对ACR—g—VC树脂力学性能的影响

叙速了采用在ACR链上接枝氟乙烯（VC）单体达到对PVC树脂增韧改性的目的、研究结果表明：ACR的抗冲效果与ACR胶乳特性密切相关，合成PBA时B（交联剂）最佳用量为1％左右；BA／MMA最佳投料比80／20左右，ACR—g—VC抗冲强度随ACR含量增加而增加；制得的ACR—g—VC树脂性能达到Vinnolit公司同类产品H2264z树脂实测水平。     

长链支化制备高熔体强度PP的研究

通过长链支化来改性PP，从而得到高熔体强度的PP。实验以丙烯酸酯类单体为接枝单体，过氧化物为引发剂，对PP进行了熔融接枝，重点考察了二官能团单体的改性情况。实验结果表明，二三官能团单体的改性效果较为明显；熔体流动速率随单体加入量增加而降低，随过氧化物浓度增加而升高；拉伸粘度谱图显示有明显的应变硬化现象；改性后产物的熔体强度变化明显；纯化后的产物经工外，差示扫描量热分析表明接枝反应的发生；索氏萃取法没有检测到凝胶的生成。     

水解/接枝处理对F-12纤维/环氧复合材料力学性能的影响

采用氢氧化钾稀溶液对F-12纤维进行表面处理,将—COOK离子对引入到F-12纤维表面,进而引发不同接枝单体的接枝,并分析了不同接枝单体和接枝时间等对F-12纤维拉伸强度及其环氧复合材料层间剪切强度的影响。研究表明,在温和条件下将—COOK离子对引入到F-12纤维表面,引发环氧氯丙烷接枝,可以提高F-12纤维/环氧复合材料的层间剪切强度。     

橡胶化学接枝改性的研究进展

综述了以马来酸酐、甲基丙烯酸甲酯等低分子化合物为接枝单体对橡胶进行化学接枝改性的研究及应用情况,分别介绍了反应原理、不同相之间的作用和接枝物结构与表征后,提出用该方法提高短纤维与橡胶间粘结强度的构想.     

原材料对硅烷接枝交联高熔体强度聚丙烯流动性能影响的研究

采用不饱和硅烷为接枝单体,不饱和烯烃为共单体,在双螺杆挤出机上实现均聚型聚丙烯的接枝交联,制得了高熔体强度聚丙烯。实验通过熔体指数(MFR)和凝胶含量的变化研究原材料对改性PP的影响。结果显示,体系中的试剂均严重影响材料的熔体流动性能。在硅烷和共单体共存的条件下,材料的熔体流动性能随引发剂A含量的增加而下降。共单体起到稳定大分子自由基的作用,增加了硅烷的接枝效率和接枝速率,共单体与硅烷最佳摩尔比为1∶1。改性后材料的耐热性、力学性能等均有较大提高。     

反应挤出PP/LGF复合材料的制备及性能

采用熔融浸渍工艺制备了长玻纤增强聚丙烯复合材料,研究了接枝单体GMA、MA以及引发剂DCP含量对长玻璃纤维增强聚丙烯复合材料力学性能的影响。结果表明:与采用接枝单体GMA相比,采用接枝单体MA反应挤出PP/LGF复合材料的力学性能对引发剂DCP的用量更为敏感,严重影响了PP/LGF复合材料的力学性能;当引发剂DCP质量分数为0.1%,采用接枝单体MA反应挤出PP/LGF复合材料性能最优,并且与没有添加相容剂的PP/LGF复合材料相比,拉伸强度、冲击强度分别提高31%、50%。     

紫外引发含氟单体在LDPE薄膜表面的接枝改性

研究紫外光引发甲基丙烯酸十二氟庚酯(DFHMA)在LDPE薄膜表面的接枝改性.考察辐照时间和距离,光敏剂浓度、紫外光强度对接枝率的影响.通过红外光谱分析、扫描电镜及能谱分析对接枝前后的薄膜表面进行表征,结果表明:DFHMA可以通过紫外引发接枝到LDPE等薄膜表面;并对接枝后薄膜的润湿性进行分析,结果表明:接枝含氟单体后薄膜表面能降低、润湿性减弱、接触角变大.     

Preparation of block copolymers with macro-azonitrile as an initiator

Macro-azonitriles were prepared by the reaction of azobis-alcohol with diisocyanate of polyalkylene oxide and were used as initiators for the polymerization of various vinyl monomers such as vinyl acetate, styrene, methyl methacrylate and vinyl chloride, yielding block-copolymers consisting of polyalkylene oxide and polyvinyl sequences. These block copolymers were characterized by their dynamic properties. The polymers were found to possess two transition points, one arising from the polyalkylene oxide blocks and the other from the polyvinyl sequences. A thermoplastic elastomer was obtained from the block polymerization of styrene with poly(oxytetramethylene)glycol, whose intrinsic viscosity was 2.3 dl/g and the styrene content was 33.2 wt. –%, the ultimate strength and elongation being 57 kg/cm² and 475%, respectively. The block copolymers of polystyrene and branched polyether were also synthesized and their viscoelastic properties were investigated.     

Polymeric systems for acoustic damping. III. Blends of poly(vinyl chloride), segmented poly(ether ester), and poly(methyl acrylate)

A solution blend of poly(vinyl chloride) and a segmented poly(ether ester) and blends containing these two polymers plus poly(methyl acrylate) were investigated by dynamic mechanical analysis and electron microscopy. The binary blend, which contained 75% by weight of the poly(ether ester), showed only one loss peak, but also evidence of some phase separation. It is believed that the polyether sequences of the poly(ether ester) are extensively mixed with poly(vinyl chloride). Poly(methyl acrylate) was added to spread the damping range and produce a material of potential use as an acoustic damper. It is evident from both electron microscopy and dynamic mechanical analysis that poly(methyl acrylate) is substantially incompatible in the other polymers.     

Blends of triazine‐based hyperbranched polyether with LDPE and plasticized PVC

Triazine‐based hyperbranched polyether was obtained by earlier reported method and blended with low density polyethylene (LDPE) and plasticized poly(vinyl chloride) (PVC) separately to improve some desirable properties of those linear polymers. The properties like processability, mechanical properties, flammability, etc. of those linear polymers were studied by blending with 1–7.5 phr of hyperbranched polyether. The mechanical properties were also measured after thermal aging and leaching in different chemical media. SEM study indicates that both polymers exhibit homogenous morphology at all dose levels. The mechanical properties like tensile strength, elongation at break, hardness, etc. of LDPE and PVC increase with the increase of dose level of hyperbranched polyether. The flame retardant behavior as measured by limiting oxygen index (LOI) for all blends indicates an enhanced LOI value compared to the polymer without hyperbranched polyether. The processing behavior of both types of blends as measured by solution viscosity and melt flow rate value indicates that hyperbranched polyether acts as a process aid for those base polymers. The effect of leaching and heat aging of these linear polymers on the mechanical properties showed that hyperbranched polyether is a superior antidegradant compared to the commercially used N‐isopropyl‐N‐phenyl p‐phenylene diamine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 648–654, 2007     

Binary and ternary blends of poly(vinyl chloride), hytrel,and a polyurethane

Binary blends of poly(vinyl chloride) and a poly(ether urethane) containing 20 and 40 weight percent, respectively, of poly(vinyl chloride) have been prepared by solution blending from tetrahydrofuran and their degree of mixing investigated using dynamic mechanical analysis. In the polyurethane, transitions were found at ?19°C and ?119°C. The former was attributed to the glass transition and the latter to a Schatzki type of motion of the polyether sequences. This latter transition occurred at a temperature which is higher than the literature value for the low temperature transition in poly(tetrahydrofuran), which is equivalent to the polyether sequence in the polyurethane. This discrepancy is attributed to the influence of neighboring hard segments present because of incomplete segmental phase separation of the polyurethane. For the blends only one very broad transition was observed, indicating that there was substantial mixing of these two polymers. Three ternary blends were prepared, also by solution blending, containing poly(vinyl chloride), Hytrel, and the polyurethane in the ratios 1:1:1, 1:2:1, and 2:1:1, respectively. In the first two blends there was clear evidence of phase separation. It was only in the 2:1:1 blend that an apparently significantly compatible material resulted.     

Durability of Adhesive Bonds to Zinc-Coated Steels: Effects of Corrosive Environments on Lap Shear Strength

The effects of corrosive environments on adhesive bonds to electro-galvanized, zinc/aluminum alloy coated, coated electro-galvanized, and cold-rolled steels have been investigated. Bonds prepared using a rubber-modified dicyandiamide-cured epoxy adhesive, an epoxy-modified poly(vinyl chloride)-based adhesive, an acrylic-modified poly(vinyl chloride)-based adhesive a one-part urethane adhesive, and a two-component epoxy-modified acrylic adhesive were exposed under no-load conditions to constant high humidity or cyclic corrosion exposure for 50 days or 50 cycles (10 weeks) respectively.

Over the course of this study, exposure to constant high humidity had little effect on lap shear strength for any of the systems studied. Bond failures were initially cohesive, and with few exceptions remained so.

Bond strength retention under the cyclic corrosion exposure conditions employed was strongly dependent on adhesive composition and on substrate type. On galvanized substrates, lap shear strengths for the poly(vinyl chloride)-based adhesives were reduced by 90-100% during the course of the corrosion exposure, and a change in the mode of bond failure (from cohesive to interfacial) was observed. On the coated electro-galvanized steel substrate, the poly(vinyl chloride)-based adhesives showed about 50% retention in lap shear strength and a cohesive failure throughout most of the corrosion test. The dicyandiamide-cured epoxy adhesive used in this study generally showed the best lap shear strength retention to zinc-coated substrates; bonds to cold-rolled steel were severely degraded by corrosion exposure. The performance of the acrylic and urethane adhesives were intermediate to the dicyandiamide-cured epoxy and poly(vinyl chloride)-based adhesives in strength retention.     

Durability of Adhesive Bonds to Zinc-Coated Steels: Effects of Corrosive Environments on Lap Shear Strength

The effects of corrosive environments on adhesive bonds to electro-galvanized, zinc/aluminum alloy coated, coated electro-galvanized, and cold-rolled steels have been investigated. Bonds prepared using a rubber-modified dicyandiamide-cured epoxy adhesive, an epoxy-modified poly(vinyl chloride)-based adhesive, an acrylic-modified poly(vinyl chloride)-based adhesive a one-part urethane adhesive, and a two-component epoxy-modified acrylic adhesive were exposed under no-load conditions to constant high humidity or cyclic corrosion exposure for 50 days or 50 cycles (10 weeks) respectively.

Over the course of this study, exposure to constant high humidity had little effect on lap shear strength for any of the systems studied. Bond failures were initially cohesive, and with few exceptions remained so.

Bond strength retention under the cyclic corrosion exposure conditions employed was strongly dependent on adhesive composition and on substrate type. On galvanized substrates, lap shear strengths for the poly(vinyl chloride)-based adhesives were reduced by 90–100% during the course of the corrosion exposure, and a change in the mode of bond failure (from cohesive to interfacial) was observed. On the coated electro-galvanized steel substrate, the poly(vinyl chloride)-based adhesives showed about 50% retention in lap shear strength and a cohesive failure throughout most of the corrosion test. The dicyandiamide-cured epoxy adhesive used in this study generally showed the best lap shear strength retention to zinc-coated substrates; bonds to cold-rolled steel were severely degraded by corrosion exposure. The performance of the acrylic and urethane adhesives were intermediate to the dicyandiamide-cured epoxy and poly(vinyl chloride)-based adhesives in strength retention.     

Properties of Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline Conductive Films: The Effect of Poly(ethylene glycol) Diglycidyl Ether

The effect of polyaniline and poly(ethylene glycol) diglycidyl ether on tensile properties, morphology, thermal degradation, and electrical conductivity of poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films was studied. The poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films were prepared using a solution casting technique at room temperature until a homogeneous solution was produced. Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline/poly(ethylene glycol) diglycidyl ether conductive films exhibit higher electrical properties, tensile strength, modulus of elasticity but lower final decomposition temperature than poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films. Scanning electron microscopy morphology showed that the polyaniline more widely dispersed in the poly(vinyl chloride)/poly(ethylene oxide) blends with the addition of poly(ethylene glycol) diglycidyl ether as surface modifier.     

高硬度聚氨酯灌封胶的制备及性能研究

以聚醚A、聚醚B、聚合MDI为原料,采用一步法合成了高硬度聚氨酯灌封胶,考察了聚醚配比、硬段含量、复配扩链剂配比对材料的硬度、拉伸强度、断裂伸长率、体积电阻率的影响。结果表明,随着聚醚A含量增加,材料的硬度、拉伸强度逐渐增加;体积电阻率先增加后减少,并在聚醚A和聚醚B的质量比为1：2时达到最大值;当复配扩链剂TMP和BDO质量比为1：2时,体积电阻率达4．8×10^16Ω·cm,材料的综合性能最佳,且可以满足市场需求。     

新型多氨基聚醚的合成研究

采用双金属催化剂催化环氧氯丙烷对高活性聚醚进行封端反应,得到邻氯醇聚醚,然后将邻氯醇聚醚与氨水反应得到目标产物多氨基聚醚.讨论了反应温度、原料氨水与氯甲基的摩尔比和反应时间对产物胺值的影响,并通过核磁共振结果证实了新型多氨基聚醚的生成.结果表明,反应温度为110℃、原料氨水与氯甲基的摩尔比为5:1、反应时间为6h时,得...     

氯乙烯-醋酸乙烯酯共聚物的后功能化研究

通过将氯乙烯－醋酸乙烯酯－丙烯酸羟乙醋共聚物（VAGF）与马来酸酐酯化接枝，制得带羟基的氯醋三元共聚物。探索了原料配比、催化剂用量、反应时间及反应温度对酯化接枝反应的影响，并用红外光谱进行表征。得到酯化反应的最佳条件为：催化剂用量为VAGF质量的0．8％，VAGF质量分数为15％，温度100℃，时间9h。氯乙烯－醋酸乙烯酯－丙烯酸羟乙酯三元共聚物的马来酸酐酯化活性高于氯乙烯－醋酸乙烯酯－乙烯醇三元共聚物。