Relationships of tensile strength with crosslink density for the high-carbon black-filled EPDM compounds with various softeners

Equilibrium swelling and rheological tests were adopted to systematically investigate the effects of softener type and dosage on the crosslink densities. The results turned out that the chemical crosslink density could be distinguished from the physical crosslink density by comparing the results of equilibrium swelling and rheological tests. The liquid butadiene (LB) as a softener leads to the greatest reduction in crosslink density, followed by polyethylene wax (PW) and paraffinic oil (PO). The tensile strength decreases with increasing PO content while shows peak values with increase of LB and PW contents. The dependencies of chemical crosslink density on the aging time under 150°C are quite different for the three softeners, which can be expected from the double crosslinking networks consisting of small softener and large main crosslinking networks. Further investigation has been performed to correlate the tensile strength with chemical crosslink density of ethylene propylene diene monomer elastomer vulcanizates. Three different linear relationships can be obtained for the softeners independent of the aging time. It can now be expected from this study that the role of some new softeners in rubber compounds is not only confined to plasticization but also forms crosslinking networks in the peroxide-cured rubbers.     

微晶纤维素/天然橡胶复合材料的制备及性能研究

将微晶纤维素(MCC)碱尿素溶液与天然胶乳混合,通过MCC原位析出,制备出MCC/天然橡胶(NR)复合材料,并对其性能进行研究。结果表明:原位析出的MCC可以有效增大MCC/NR复合材料的硬度和拉伸强度;MCC颗粒的尺寸和形态不均一,小尺寸的MCC颗粒与NR基体结合较好,MCC颗粒形态除球形和棒状外,还有纤维状。     

Polymers of phenylenediamines

The chemical or electrochemical oxidation of phenylenediamines in acidic aqueous media yields the corresponding oligomers or polymers. Their structures and properties are discussed in relation to a closely-related conducting polymer, polyaniline. Depending on the reaction conditions, polyphenylenediamines are produced as powders, colloidal dispersions, thin films, or composites. In contrast to polyaniline, polyphenylenediamines are rated as non-conductors and their conductivities are low. Similarly to polyaniline, these polymers display a salt–base transition and they are redox-active. They act as reductants of noble-metal compounds to the corresponding metals or as precursors in the carbonization to nitrogen-rich carbons. Applications proposed in the literature are outlined; they include the corrosion protection of metals, catalysis, electrorheology, sensors, energy-conversion devices, electrochromism, noble-metal recovery, and water treatment.     

乙烯-乙酸乙烯酯共聚物Levapren 800硫化胶溶度参数的测定及应用

采用溶胀实验及计算机HSPiP软件对牌号为Levapren 800的乙烯-乙酸乙烯酯硫化胶的溶度参数进行了研究。结果表明,单一溶剂与混合溶剂都可用于Levapren 800硫化胶溶度参数的测定,用溶胀法测得其一维溶度参数(δt)为18.90~19.25(J/cm3)1/2。通过HSPiP软件测得Levapren 800硫化胶的δt为19.97(J/cm3)1/2;三维溶度参数的色散力、极性力和氢键力溶度参数分别为18.20,5.50,6.10(J/cm3)1/2。利用三维溶度参数可以预测Levapren 800硫化胶在标准实验油中的溶胀行为;相对能量差对预测聚合物在溶剂中的溶胀性能方面具有一定的应用价值。     

促进剂种类对ZnO硫化BIIR的影响

通过改变促进剂种类,研究了ZnO-促进剂硫化体系对溴化丁基橡胶(BIIR)硫化特性、硫化反应动力学参数及硫化胶物理机械性能的影响。研究表明,促进剂二硫化二苯并噻唑(MBTS)、N-环己基-2-苯并噻唑次磺酰胺(CBS)抑制了ZnO对BIIR的硫化,使硫化胶的交联密度降低,硫化胶的物理机械性能下降;促进剂二硫化四甲基秋兰姆(TMTD)和二甲基二硫代氨基甲酸锌(ZDMC)则促进了ZnO对BIIR的硫化,提高了硫化胶的物理机械性能;MBTS、TMTD、ZDMC均降低了ZnO硫化BIIR的反应活化能。     

水对阻燃高回弹聚氨酯泡沫塑料性能的影响

探讨了水与多元醇的质量比对阻燃高回弹聚氨酯泡沫塑料的反应活性、泡孔结构及制品性能的影响。结果表明:随着水与多元醇的质量比增大,制品的乳白、到顶和上升时间均呈下降趋势,泡孔孔径逐渐变小,制品的玻璃化转变温度上升,制品的拉伸强度逐渐上升,断裂伸长率逐渐降低,制品的氧指数从25.0%降低到22.5%。     

乙二醇二缩水甘油醚环碳酸酯的合成及表征

采用二氧化碳插入法,以季铵盐为催化剂,在高温高压下合成环碳酸酯。讨论了温度、压力、催化剂对转化率的影响,并通过红外和核磁谱图表征了环碳酸酯的结构。结果表明:以乙二醇二缩水甘油醚为原料,四丁基溴化铵为催化剂时,最佳工艺条件为温度100℃,CO2压力2.0 MPa,催化剂的质量为环氧化物的3%。     

海泡石的结构及在阻燃聚合物材料中的应用研究进展

简要介绍了海泡石的基本结构,系统介绍了海泡石在常见聚合物复合材料阻燃领域的应用,着重讨论了海泡石的改性及与其他阻燃剂协同作用在聚合物中的阻燃效果,并对其应用前景进行了展望。