丙烯腈含量对螺杆泵定子橡胶机械物理性能的影响

本文通过对不同丙烯腈含量的丁腈橡胶的耐油性能、耐磨损试性能和耐疲劳性能进行研究,分析了丙烯腈含量对螺杆泵定子橡胶机械物理性能的影响。结果表明,随丙烯腈含量的增加,丁腈橡胶的力学性能和耐油性增强;在55℃的工作温度下,N220S橡胶的损耗因子最小;丙烯腈含量越高,其耐磨损性能越差;丙烯腈含量最高的橡胶,耐屈挠性能和耐伸张疲劳性能最好。     

丙烯腈-丁二烯橡胶中结合丙烯腈含量标准物质均匀性和稳定性研究

丙烯腈-丁二烯橡胶中结合丙烯腈含量标准物质的研制,均匀性和稳定性研究及检验是非常重要的环节之一,样品的均匀和稳定也是标准物质研制的前提条件。本文按照标准物质均匀性和稳定性检验的相关要求,对丙烯腈-丁二烯橡胶中结合丙烯腈含量标准物质进行了均匀性、稳定性研究和检验,并采用方差分析法进行检验结果的统计,通过统计其F值为1.24,小于临界值F₍(0.05,14,30))2.04,表明研制的标准物质均匀;并用直线拟合法对短期和长期稳定性进行检验,表明标准物质在短期和长期均稳定。因此,该研究丙烯腈-丁二烯橡胶中结合丙烯腈含量标准物质满足标准物质均匀性和稳定性的要求。     

ABS的组成与性能研究进展(Ⅱ)

综述了苯乙烯-丙烯腈共聚物(SAN)和丙烯腈-丁二烯-苯乙烯共聚物(ABS)组成与性能的研究。不同丙烯腈含量SAN间的相容性与丙烯腈含量差值有关。SAN相对分子质量越低,保持相容性的丙烯腈含量差值可以越大。丙烯腈含量影响SAN的韧性。橡胶增韧时,SAN基体树脂中的丙烯腈含量高于SAN接枝物为佳,接枝率或界面黏结力适度为宜。橡胶相玻璃化转变温度的变化反映了SAN接枝橡胶和SAN基体树脂相互作用。大粒径胶粒(大于1μm)与小粒径胶粒(小于0.5μm)组合增韧SAN产生协同效应。大粒径胶粒诱发银纹,小粒径胶粒终止银纹或改变银纹增长途径。     

橡胶含量对ABS成品性能的影响

以橡胶含量为40％和60％的丙烯腈—丁二烯——苯乙烯共聚物(ABS)粉料分别与苯乙烯，丙烯腈共聚物掺混造粒，制备一系列不同橡胶含量的ABS成品，分析了不同橡胶含量ABS成品性能，比较了高橡胶含量和低橡胶含量的ABS粉料对成品性能的影响。研究结果发现，在橡胶含量相同的情况下，使用高橡胶含量的ABS粉料，成品的力学性能较为优异。     

ABS的组成与性能研究进展(Ⅰ)

综述了苯乙烯-丙烯腈共聚物(SAN)和丙烯腈-丁二烯-苯乙烯共聚物(ABS)组成与性能的研究.不同丙烯腈含量SAN间的相容性与丙烯腈含量差值有关.SAN相对分子质量越低,保持相容性的丙烯腈含量差值可以越大.丙烯腈含量影响SAN的韧性.橡胶增韧时, SAN基体树脂中的丙烯腈含量高于SAN接枝物为佳,接枝率或界面黏结力适度为宜.橡胶相玻璃化转变温度的变化反映了SAN接枝橡胶和SAN基体树脂的相互作用.大粒径胶粒(大于1 μm)与小粒径胶粒(小于0.5 μm)组合增韧SAN产生协同效应.大粒径胶粒诱发银纹,小粒径胶粒终止银纹或改变银纹增长途径.     

ABS树脂的冲击韧性极限及形变机理的研究

将苯乙烯-丙烯腈共聚物接枝聚丁二烯（PB-g-SAN）与苯乙烯-丙烯腈共聚物（SAN）树脂按照一定比例熔融共混制备具有不同橡胶含量的丙烯腈-丁二烯-苯乙烯共聚物（ABS）树脂。研究了不同橡胶含量对ABS树脂的冲击以及拉伸行为的影响,并通过透射电子显微镜研究了ABS树脂的微观形态及形变机理。结果表明,ABS材料的冲击强度随着橡胶含量的增加先升高后降低;断裂伸长率随着橡胶含量的增大而增大;当橡胶含量较少时,橡胶粒子在基体相中发生聚集现象的可能性较小,分散性较好;随着橡胶含量的增加发生聚集现象的可能性增加,粒子分散性变差;随着橡胶粒子含量的增加,ABS树脂的主要增韧机理是由空洞化到银纹再到剪切屈服的转变。     

PBA-g-SAN对ASA树脂结构与性能的影响

采用种子乳液聚合方法,合成一系列苯乙烯-丙烯腈共聚物接枝聚丙烯酸丁酯（PBA-g-SAN）核壳接枝共聚物,将其与苯乙烯-丙烯腈共聚物（SAN树脂）熔融共混,制得ASA树脂,使用动态力学分析仪和扫描电子显微镜考察了扩径中接枝剂的含量和PBA橡胶粒径对ASA树脂性能的影响。结果表明,随着接枝剂含量的增加,PBA-g-SAN接枝共聚物的接枝率升高,当接枝剂占单体BA的3%时,ASA树脂的冲击强度达到110 J/m。ASA树脂的冲击强度随着橡胶粒径的增加先升高后降低。PBA-g-SAN接枝共聚物中PBA的玻璃化转变温度(（Tg）随着接枝剂含量的增加而升高,随着PBA橡胶粒径的增加先降低后升高。当PBA橡胶粒径为92.7 nm时,橡胶粒子发生聚集,其他粒径的PBA橡胶均可较好地分散在基体中。     

丁腈橡胶和氢化丁腈橡胶(三)

4.4硫化胶的性能 丙烯腈系橡胶最重要的特性是耐油.NBR的许多特性很大程度上取决于聚合物中丙烯腈的含量.表15为不同丙烯腈含量的NBR未硫化胶和硫化胶的性能(胶料配方相同,硫黄硫化)[54].     

胶含量对SAN/ABS共混物的结构与性能的影响

采用乳液聚合技术合成聚丁二烯胶乳,然后在聚丁二烯胶乳粒子上接枝苯乙烯和丙烯腈单体制备ABS粉料,通过熔融共混法制备了苯乙烯-丙烯腈/丙烯腈-丁二烯-苯乙烯(SAN/ABS)共混物。对共混物进行了力学性能测试,结果表明:随着橡胶含量的增加,共混物的断裂伸长率先上升后下降,冲击强度增大。采用转矩流变仪和扫描电镜(SEM)对共混物的加工流变性能和共混物的相形态进行了表征,结果表明:胶含量为25%时,加工流动性较好,橡胶粒子能较均匀地分散在基体中,能较好地改善体系的抗冲击性。     

红外法测定液体橡胶中丙烯腈含量

液体橡胶中丙烯腈含量的测定一般采用经典的凯乐定氮法,此方法不驻费时而且操作繁琐。用红外分光光度法测定胶中丙烯腈含量,所得结果与凯乐定氮法相同,但比凯氏定氮法简便、快速。     

Role of functionalized terminal groups in formation of nanofibrillar morphology of hyperbranched polyesters

A series of amphiphilic hyperbranched polymers with a polyester-polyol core and 64 terminal hydroxyl groups were modified by substituting various terminal groups: alkyl tails, amino, and carboxyl groups. The effect of the pendant groups' chemical composition on the resulting surface morphology within Langmuir-Blodgett monolayers with respect to their ability to form nanofibrillar surface structures was investigated. We demonstrated that the amphiphilicity of the polyester core with 64 hydroxyl groups can be achieved if a fraction of alkyl tails (C15) is higher than 1/4. Nanofibrillar morphology was consistently formed as the highly polar functional groups were added to the polyester cores in combination with a significant (>30%) fraction of alkyl terminal groups. Addition of amino end groups was observed to be much more effective in promoting the nanofibrillar assembly than the addition of carboxyl end groups.     

Syntheses of cellulose exchangers carrying chelating anchor groups for selective separation of uranyl ions

Syntheses of cellulose exchangers carrying tailor-made chelating anchor groups are described. One type of anchor groups offers three coplanar carboxy groups for the complexation of UO²⁺₂, a second type coplanar amidoxime-hydroxamic acid groups and a third type amidrazone-hydrazide groups. The distance of the groups is varied by use of different terminal dibromo-n-alkanes. The anchor groups of type 1 are obtained from malonic acid diethyl ester and dibromalkanes, type 2 and 3 from cyanacetic acid ethylester and dibromoalkanes. The products containing malonic acid diethylester and alkane groups or cyanoacetic acid ethylester and alkane groups, respectively, in the mole ratio 3 : 2 are coupled with hydrazinedesoxycellulose. The carboxy groups are set free by hydrolysis of the ethyl esters in case of type 1, whereas the anchor groups of types 2 and 3 are obtained by reaction with hydroxylamine and with hydrazine, respectively. The procedures of the syntheses are presented in detail. The products are characterized by the degree of substitution and the content of the individual groups. The anchor groups are inverstigated by means of their ¹H-NMR spectra. The exchange properties are discussed.     

Changes of oxygen-containing groups during thermal treatment and their influences on moisture readsorption of lignite

The changes in oxygen-containing groups in the thermal treatment process of lignite were analyzed and the moisture readsorption amounts of upgraded coals were related in this study. A chemical titration method was applied to determine the types and contents of oxygen-containing groups in raw lignite and upgraded coals obtained in the temperature range of 353–633 K under atmospheres of argon, air, and carbon dioxide. Experimental results showed that the oxygen-containing groups mainly involved carbonyl, phenolic hydroxyl, and carboxylic groups (including carboxyl and carboxylate), among which phenolic groups were dominant. These different oxygen-containing groups decomposed discriminatingly with temperature according to thermal stability. The removal of oxygen-containing groups proceeded more easily in a CO₂ atmosphere compared to in Ar. The oxidation reaction occurring on the surface of lignite exposed to air led to an increase in oxygen-containing groups. The different types of oxygen-containing groups possessed various combining abilities with water, among which carboxyl was considered the most important group for the moisture readsorption. Decomposition of oxygen-containing groups in the thermal treatment process of lignite mainly caused a reduction in monolayer water adsorption and further decreased the multilayer water.     

Aerial oxidation of brown coals following exchange of acidic groups

The exchange of acidic groups in a brown coal with barium promotes oxidation during air-drying of the exchanged coal. The oxidation results in the formation of carboxyl groups and carbon dioxide. If the exchange involves phenolic groups the carbon dioxide generated during oxidation is retained in the coal as carbonate, and the carboxyl groups are formed as carboxylates at the expense of the phenolic groups. Decarboxylation of these carboxyl groups is considered to produce the carbon dioxide evolved when the exchanged coal is refluxed with water or acid. In the determination of acidic groups, provided oxidation is kept to a minimum during exchange, the interference due to any barium carbonate formed is small and may be ignored.     

Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification

A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.     

Influence of phenyl group number on enantioseparation performance of chitosan-based materials

In order to investigate the influence of phenyl group number on enantioseparation capability of a chitosan-based chiral selector (CS), in this study, two series of chitosan derivative and their enantioseparation were presented. According to the functional group at 2-position of glucosamine, the derivatives were classified as amido-type and ureido-type. In the amido-type CSs, the CS with two phenyl groups showed the best enantioseparation capability; the CS with one phenyl group exhibited the poorest enantioseparation; and the enantioseparation performance of the CS with three phenyl groups intermediated between those of the CSs with one and two phenyl groups. In the ureido-type, the CS bearing three phenyl groups was in the middle of two CSs with two phenyl groups in enantioseparation capability. Based on the results obtained in the present study, one phenyl group in a chitosan derivative is not enough for enantioseparation, and two or three phenyl groups are necessary. On the other hand, introducing three phenyl groups onto one glucosamine unit of chitosan, can not definitely result in a better enantioseparation capability, comparing with introducing two phenyl groups.     

Thermogravimetric and qualitative analysis of thermal decomposition characteristics of polyurethane foams based on polyols with carbamide or oxamide and borate groups

The thermal stability and the kinds of products of thermal decomposition of polyurethane foams modified with urea or oxamide and borate groups were studied. Incorporation of urea or oxamide groups and borate groups enhances the thermal stability of polyurethane foams compared to polyurethane foams based on typical polyols. Thermal stability of foams modified with oxamide groups is somewhat higher that of foams modified with urea groups. In turn, simultaneous incorporation of borate groups results in an increase in thermal stability of the foams modified with urea. The temperature of thermal decomposition of the foams with oxamide and borate groups does not change or undergoes a slight decrease. The thermal degradation products of investigated foams are similar and they are usually water, ammonia, carbon dioxide and/or nitrous oxide. Additionally, hydrogen cyanide can be released during thermal decomposition of polyurethane foams modified with urea groups. The presence of borate groups prevents the formation of hydrogen cyanide. The opposite situation is observed in the case of the foams modified with oxamide and borate groups. Thus, from the point of view of a fire hazard, the use of the foams modified with urea and borate groups is safer. © 2017 Society of Chemical Industry     

磺酸型水性聚氨酯分散液的制备方法与性能

叙述了磺酸型水性聚氨酯分散液的分散性、固含量以及胶膜性能,除与低聚物二元醇、二异氰酸酯、扩链剂种类及合成工艺有关外,与磺酸根在聚氨酯大分子中的引入方式密切相关.从磺酸根不同引入方式,即磺酸根是从链端引入还是在链上引入,链上引入又分软段引入和硬段引入,详细介绍了不同引入方式和制备磺酸型水性聚氨酯分散液的工艺及性能.     

Sugar-binding property of magnetite particles modified with dihydroxyborylphenyl groups via graft polymerization of acrylic acid

In order to combine sugar-binding property and magnetism, dihydroxyborylphenyl (DHBP) groups were attached to magnetite particles via graft polymerization of acrylic acid. The graft polymerization was carried out in a redox system consisting of mercapto groups introduced onto the surfaces of magnetite particles and ceric ions. DHBP groups were attached through amide linkages by the condensation reaction of 3-aminophenylboronic acid with carboxyl groups of the grafted poly(acrylic acid). Complexation of the attached DHBP groups was examined with various sugars and compared with that of the free phenylboronic acid. The attached DHBP groups gave a large value of binding constant K for the complexation with adenosine having a pair of cis-OH groups, whereas the K values for the DHBP groups with adenosine phosphates were extremely small. With respect to the complexation with 2′-deoxyadenosine, cooperative interaction of neighboring DHBP groups was suggested. Although the value of acidity index pK_a of the attached DHBP was larger than that of free phenylboronic acid, the pK_a value was decreased by coexistent basic groups.     

Effects of additives with different functional groups on the physical properties of starch/PVA blend film

The effects of additives with different functional groups, that is, hydroxyl and carboxyl groups, on the physical properties of starch/PVA blend films were examined. Starch/PVA blend films were prepared by the mixing process. Glycerol (GL) with 3 hydroxyl groups, succinic acid (SA) with 2 carboxyl groups, malic acid (MA) with 1 hydroxyl and 2 carboxyl groups, and tartaric acid (TA) with 2 hydroxyl and 2 carboxyl groups were used as additives. The results of measured tensile strength and elongation verified that hydroxyl and carboxyl groups as functional groups increased the flexibility and strength of the film. The degree of swelling (DS) and solubility (S) of the GL/SA‐added films were low. However, the DS and S of the films with added MA or TA with both hydroxyl and carboxyl groups were comparatively high. When the film was dried at low temperature, the properties of the films evidently improved, probably because hydrogen bonding was activated at low temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3733–3740, 2006