原位接枝炭黑/天然橡胶复合材料的制备及性能

采用原位固相接枝方法,使在高温和强剪切作用下降解的天然橡胶接枝到炭黑表面.通过对接枝前后炭黑填充天然橡胶的性能对比发现,原位接枝炭黑不但能提高天然橡胶的硫化速度,还能提高拉伸强度,定伸应力和撕裂强度等;动态力学性能的测试结果表明接枝炭黑填充的天然橡胶中接枝炭黑网络化程度较低,这些结果主要归因于接枝炭黑在橡胶基体中分散性的改善及炭黑与橡胶之间作用力的增加.     

废轮胎和天然橡胶在超临界甲苯中的解聚研究

在300 ℃～360 ℃、3.7 Mpa～7.0 Mpa、反应20 min～90 min、投料比(甲苯与废轮胎或天然橡胶的质量比)5.0～10.0下,分别研究了废轮胎和天然橡胶在超临界甲苯中的解聚,着重考察了解聚率与反应条件的关系、以及解聚产物分布.在临界点附近,解聚率随温度、压力升高而增加;高于临界压力后,压力对解聚率的影响减弱.解聚产物主要为液相物和固相物,液相产物用色质联谱(GC/MS)分析表明,以芳香烃和烯烃类为主,且分子量大多小于300;固相产物经分析以碳黑为主.废轮胎和天然橡胶的解聚产物大部分是相似的,天然橡胶可以完全解聚,在同样条件下废轮胎解聚率低于天然橡胶.超临界甲苯在反应中对实验样品不仅起到溶胀和溶解作用,同时也参与了解聚反应.研究结果为选择解聚介质和操作参数提供了依据.     

橡胶基多效协同自修复防水复合材料的研究

制备了环氧树脂改性高吸水纤维,随后将改性纤维与天然橡胶通过混、流延、压延、硫化等工艺制备了环境友好型三层复合自修复防水材料,通过SEM、FT-IR、TY-8000万能材料试验机、BTS-001电动不透水仪等考察了自修复防水材料的微观结构、机械性能、抗氧化性能、自修复性能及防渗透性能等。结果表明,高吸水纤维有助于提高其拉伸强度,最大拉伸强度为1.83MPa,断裂伸长率达到700%以上。防水材料完全切断,自修复24h后,其切口部分无可见痕迹,裂口完全愈合,且24h内无水滴渗漏。自修复48h后拉伸强度可达原始材料的2.36倍,断裂伸长率达到80%左右。     

碱金属离子X型沸石的固相离子交换及其催化性能的研究

本文考察了水合13X沸石与碱金属盐类间的固相离子交换反应,并对交换样品的比表面、孔容和异丙醇分解反应活性进行了测定.结果表明,这种类型的固相离子交换在室温下即可发生.体积较大的Cs~+比K~+难于交换,高温焙烧有利于提高Cs~+的交换度.固相交换样品的比表面、孔容变化和异丙醇分解反应活性都与液相交换样品相同,只是交换度的函数,与交换方法无关.与K~+交换样品相比,Cs~+交换样品中Cs~+离子更多地占据超笼,导致更高的超笼局部碱性和脱氢反应活性.     

不同硫化体系天然橡胶复合材料力学性能的影响

研究了不同硫化体系对炭黑填充天然橡胶力学性能的影响。结果表明,以N-(氧化二亚乙基)-2-苯并噻唑次磺酰胺(NOBS)为主促进剂的四种硫化体系中,半有效硫化体系硫化的橡胶的综合性能最好。在以N-环己基-2-苯骈噻唑次磺酰胺(CBS)+2-硫醇基苯骈噻唑(M)为促进剂的四种硫化体系中,用普通硫化体系(CV)硫化得到的碳黑/天然橡胶的综合性能最优。本文还研究了不同硫化体系对炭黑/碳纳米管填充天然橡胶力学性能的影响,结果表明,普通硫化体系(CV)硫化得到的碳纳米管/碳黑/天然橡胶的综合性能最优。     

基于金属配位键的自修复、 可重塑聚丁二烯橡胶的合成及性能

橡胶材料通常因经过硫化及补强等工艺处理而呈现出热固性, 因而难以被回收处理, 容易造成严重的资源浪费和环境污染. 本文通过在聚丁二烯上修饰羧酸基团, 再加入锌离子(Zn²⁺)与羧酸配位, 制备了基于金属配位键交联的自修复橡胶(PB-COOH/Zn²⁺). 该橡胶具有良好的机械性能和优秀的自修复及重塑性能, 在70 ℃下修复3 h, 其韧性可以恢复到初始强度, 修复效率可达100%. PB-COOH/Zn²⁺较高的聚合物链段运动能力及配位键交联网络良好的动态性不仅赋予其优异的修复性能, 还使得其在较温和的条件下可以进行多次重塑, 在70 ℃及5 MPa的条件下重塑3次仍能保持原有的机械性能. 此外, 通过在PB-COOH/Zn²⁺中掺杂适量的碳纳米管, 不仅增强了其机械性能, 还使其具备了电致修复及传感能力, 扩宽了PB-COOH/Zn²⁺作为环境友好型材料的应用前景.     

热可逆自修复环氧树脂的合成与修复行为

采用环氧氯丙烷与糠醇反应合成了含二烯体结构的环氧单体,并与含亲二烯体结构的双马来酰亚胺反应,制备得到基于热可逆Diels-Alder反应的自修复环氧树脂(EP-DA).分别利用FTIR、DSC以及gel-sol转变对EP-DA的化学结构、热性能以及热可逆性进行了分析表征.结果表明,向EP-DA中引入了热可逆DA键,从而赋予环氧树脂良好的热可逆性和再加工性能,使环氧树脂实现自修复,并可使废弃环氧树脂能够得以回收再利用.模拟环氧树脂实际使用中受冲击破坏情况,采用宏观定性观察和弯曲载荷恢复定量测定相结合,对环氧树脂的修复行为和多次修复能力进行了考察,证实这种材料具有良好的自修复性能和多次重复修复能力,其一次修复效率达到了77.1%,同一试样经由3次冲击破坏—热处理后,其修复效率仍然高达53.9%.     

硅土/白炭黑复合填料对天然橡胶硫化胶性能的影响

硅土主要是由低温石英和粘土矿物组成的非金属矿物,具有独特的粒片叠置结构。本工作采用经改性处理的硅土与白炭黑并用,测定硅土/白炭黑复合填料对天然橡胶(NR)的硫化特性和力学性能,探讨填料并用对天然橡胶性能的影响。实验结果表明:经改性处理,硅土平均粒径减小,疏水性增强。硅土与白炭黑并用,有利于增强NR硫化初期的流动性,延长焦烧时间而不明显降低硫化速率,能改善橡胶的加工性能。拉伸性能测试结果表明,复合填料与白炭黑或硅土单独使用相比,能显著提高填充NR硫化胶的拉伸强度、定伸应力、交联密度,而不降低橡胶弹性。当硅土占复合填料质量为40%时,NR硫化胶的拉伸强度达到最大。动态机械性能测定结果表明,相比白炭黑,硅土更有利于减小硫化胶的生热和滚动阻力。     

热可逆自修复环氧树脂的合成与修复行为

采用环氧氯丙烷与糠醇反应合成了含二烯体结构的环氧单体,并与含亲二烯体结构的双马来酰亚胺反应,制备得到基于热可逆Diels-Alder反应的自修复环氧树脂(EP-DA).分别利用FTIR、DSC以及gel-sol转变对EP-DA的化学结构、热性能以及热可逆性进行了分析表征.结果表明,向EP-DA中引入了热可逆DA键,从而赋予环氧树脂良好的热可逆性和再加工性能,使环氧树脂实现自修复,并可使废弃环氧树脂能够得以回收再利用.模拟环氧树脂实际使用中受冲击破坏情况,采用宏观定性观察和弯曲载荷恢复定量测定相结合,对环氧树脂的修复行为和多次修复能力进行了考察,证实这种材料具有良好的自修复性能和多次重复修复能力,其一次修复效率达到了77.1%,同一试样经由3次冲击破坏—热处理后,其修复效率仍然高达53.9%.     

沥滤法制备低蛋白天然橡胶的硫化动力学研究

鉴于离心法制备低蛋白天然橡胶需要繁重设备和繁琐的工艺,本研究拟采用碱性蛋白酶处理天然胶乳,然后多次沥滤配合绉片的方法制备低蛋白天然橡胶。对比沥滤法低蛋白天然橡胶与离心法低蛋白天然橡胶的交联密度、力学性能和硫化特性参数。结果表明,沥滤法低蛋白天然橡胶的交联密度高,拉伸强度大,硫化速率快,硫化反应活化能低。     

配位交联的NBR/PVC合金的制备及表征

橡胶通常是通过共价键将线型高分子交联成三维网状结构,而交联过的橡胶不溶不熔,很难再生利用,对环境造成严重污染,为了解决橡胶材料再生利用问题,许多人尝试将一些非共价键用于橡胶的交联,如热塑性弹性体(物理交联)、离子弹性体Ⅲ及通过氢键交联的橡胶,然而由于上述非共价键作用较弱,导致材料力学性能较差及高温使用性能下降,配位键是所有非共价键中最强的键,     

Bio‐based epoxy vitrimers: Reprocessibility,controllable shape memory,and degradability

The research activities in the development of recyclable and reprocessable covalently crosslinked networks, and the construction of polymers from renewable resources are both stemmed from the economical and environmental problems associated with traditional thermosets. However, there is little effort in combination of these two attractive strategies in material designs. This article reported a bio‐based vitrimer constructed from isosorbide‐derived epoxy and aromatic diamines containing disulfide bonds. The resulted dynamic epoxy resins showed comparable thermomechanical properties as compared to similar epoxy networks cured by traditional curing agent. Rheological tests demonstrated the fast stress relaxation of the dynamic network due to the rapid metathesis of disulfide bonds at temperature higher than glass transition temperature. This feature permitted the recycling and reprocessing of the fragmented samples for several times by hot press. The dynamic epoxy resins also exhibited shape‐memory effect, and it is demonstrated that the shape recovery ratio could be readily adjusted by controlling the stress relaxation in the temporary state at programming temperature. Moreover, the degradability of the dynamic epoxy resins in alkaline aqueous solution was also demonstrated. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1790–1799     

Solid-state carbon-13 NMR Studies of vulcanized elastomers. V. Observation of new structures in sulfur-vulcanized natural rubber

The complementary application of the NMR inversion recovery measurements and the computer fitting of the overlapping spectral region is found to be a useful method for structural analysis of vulcanized natural rubber in the solid state. Since the linewidths in ¹³C-NMR spectra of solids are relatively broad compared with the differences between chemical shifts, some weak signals are completely obscured in the resulting spectra. If the resonances have sufficiently different relaxation times, such as methyl and methylene carbons, it is possible to detect neighboring heavily overlapped signals by using the inversion recovery delay τ value at which the interfering strong resonance has null intensity. The 20 resonances observed in the spectra of crosslinked rubbers are tentatively assigned to the structural units formed during the vulcanization process. It is found that vulcanizates containing smaller amounts of sulfur (1 and 3%) show insignificant changes in the NMR spectra for curing times of 30 and 90 min. Structural modifications in rubbers cured with 10% sulfur continuously increase with the increasing curing time up to 120 min, indicating a significant loss in double bonds in the later stages of the reaction.     

硫化天然橡胶物理松弛时间的测量

硫化天然橡胶物理松弛时间的测量裘怿明刘从伟时锋傅政（青岛化工学院橡胶工程学院青岛２６６０４２）关键词硫化天然橡胶，应力松弛速率，数值计算方法，曲线拟合高分子热运动的特点之一是存在松弛现象，通常，人们描述高分子材料的松驰速度采用松驰时间τ［１］．实际...     

Aromatic amine‐terminated polysulfide oligomer: Synthesis and application in self‐healable polyurea

The dynamic chemistry of disulfide bonds has emerged as one of the most powerful tools used for the fabrication of organic compounds and self‐healing materials. In this article, a novel aromatic amine‐terminated polysulfide oligomer is first synthesized from thiol‐terminated polysulfide oligomer and bis(4‐aminophenyl) disulfide via disulfide metathesis mechanism. The resulting oligomer is confirmed by FTIR and ¹H NMR spectra and then successfully applied in constructing self‐healable polyurea material (A‐LP23‐I), which combines the advantages of higher strength of polyureas and excellent self‐healing ability of polysulfide‐based materials. After subjecting to a temperature of 75 °C for 48 h, both the tensile strength and ultimate elongation of A‐LP23‐I restore to more than 90% of the original values (3.32 MPa and 396%). This study demonstrates a novel strategy for synthesizing aromatic amine‐terminated oligomer. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1460–1466     

基于多重动态共价键的环氧类玻璃网络的制备与性能

以三羟甲基丙烷三缩水甘油醚(TTE)为基体, 2,2′-(1,4-亚苯基)-双[4-硫醇1,3,2-二氧杂戊烷](BDB)和3,3-二硫代二丙酸(DTDPA)为交联剂, 通过环氧-巯基“点击”反应和环氧-羧酸酯化反应, 制备了基于多重动态共价键(硼酸酯键、 二硫键和酯键)的环氧类玻璃网络. 利用红外光谱和拉曼光谱对其结构进行了表征, 结果表明, 环氧类玻璃中不仅存在硼酸酯键、 二硫键和酯键, 还存在可逆氢键, 并且大量氢键的存在能提高环氧类玻璃的交联度. 对所得环氧网络的热稳定性、 热机械性能和力学性能进行了测试, 并对基于多重动态共价键环氧网络进行了自修复、 焊接、 形状记忆和再加工能力测试. 结果表明, 在80 ℃下可实现网络的完全自修复、 再加工与焊接, 且焊接后样品的力学性能(拉伸强度)恢复率在80%以上, 具有优异的功能性.     

Dynamic Diselenide Bonds: Exchange Reaction Induced by Visible Light without Catalysis

Dynamic covalent bonds are extensively employed in dynamic combinatorial chemistry. The metathesis reaction of disulfide bonds is widely used, but requires catalysis or irradiation with ultraviolet (UV) light. It was found that diselenide bonds are dynamic covalent bonds and undergo dynamic exchange reactions under mild conditions for diselenide metathesis. This reaction is induced by irradiation with visible light and stops in the dark. The exchange is assumed to proceed through a radical mechanism, and experiments with 2,2,6,6‐tetramethylpiperidin‐1‐yloxyl (TEMPO) support this assumption. Furthermore, the reaction can be conducted in different solvents, including protic solvents. Diselenide metathesis can also be used to synthesize diselenide‐containing asymmetric block copolymers. This work thus entails the use of diselenide bonds as dynamic covalent bonds, the development of a dynamic exchange reaction under mild conditions, and an extension of selenium‐related dynamic chemistry.     

Cleaving Direct‐Laser‐Written Microstructures on Demand

Using an advanced functional photoresist we introduce direct‐laser‐written (DLW) 3D microstructures capable of complete degradation on demand. The networks consist exclusively of reversible bonds, formed by irradiation of a phenacyl sulfide linker, giving disulfide bonds in a radical‐free step‐growth polymerization via a reactive thioaldehyde. The bond formation was verified in solution by ESI‐MS. To induce cleavage, dithiothreitol causes a thiol–disulfide exchange, erasing the written structure. The mild cleavage of the disulfide network is highly orthogonal to other, for example, acrylate‐based DLW structures. To emphasize this aspect, DLW structures were prepared incorporating reversible structural elements into a non‐reversible acrylate‐based standard scaffold, confirming subsequent selective cleavage. The high lateral resolution achievable was verified by the preparation of well‐defined line gratings with line separations of down to 300 nm.     

Dual Sulfide–Disulfide Crosslinked Networks with Rapid and Room Temperature Self‐Healability

Polymer‐based crosslinked networks with intrinsic self‐repairing ability have emerged due to their built‐in ability to repair physical damages. Here, novel dual sulfide–disulfide crosslinked networks (s‐ssPxNs) are reported exhibiting rapid and room temperature self‐healability within seconds to minutes, with no extra healing agents and no change under any environmental conditions. The method to synthesize these self‐healable networks utilizes a combination of well‐known crosslinking chemistry: photoinduced thiol‐ene click‐type radical addition, generating lightly sulfide‐crosslinked polysulfide‐based networks with excess thiols, and their oxidation, creating dynamic disulfide crosslinkages to yield the dual s‐ssPxNs. The resulting s‐ssPxN networks show rapid self‐healing within 30 s to 30 min at room temperature, as well as self‐healing elasticity with reversible viscoelastic properties. These results, combined with tunable self‐healing kinetics, demonstrate the versatility of the method as a new means to synthesize smart multifunctional polymeric materials.

     

Effect of sacrificial bond on molecular dynamics and rheological behavior of hybrid butadiene-styrene-vinylpyridine rubber vulcanizates with reversible sacrificial network

Due to the improvement of strength and toughness at the same time, construction of reversible sacrificial bond network has attracted extensive attention to realize the high performance and functionalization of rubber materials. However, the research on the viscoelastic behavior of vulcanized rubber with reversible sacrificial bond network lags behind seriously. In this work relaxation kinetics, linear rheological behavior and nonlinear rheological behavior of hybrid crosslinked butadiene-styrene-vinylpyridine rubber (VPR) with reversible Zn²⁺-pyridine coordination bond were investigated in detail. It was found that, the tensile results under small strain were more conducive to reflect the contribution of sacrificial bond after sequential tensile-recovery process than those under large strain. Although sacrificial bond could affect both G' and G" at low temperature, the contribution of it to G" was more prominent. When the temperature was higher than the dissociation temperature of Zn²⁺-pyridine coordination bond, the sacrificial bond could only affect G", which was due to the fact that the pyridine group was equivalent to the graft on VPR backbone and acted as dangling chain. In addition, the destruction and reconstruction of coordination bond was the dominant factor in modulus recovery.