ATRP法制备纳米铜/PMMA-b-PSt复合粒子及其表征

在超声辐射作用下,以α-溴代丙酸乙酯为引发剂,溴化亚铜/2,2-联吡啶为催化体系,通过原子转移自由基聚合（ATRP）制备了预聚物聚甲基丙烯酸甲酯（PMMA-Br）.以此预聚物为大分子引发剂,苯乙烯为共聚单体进行ATRP反应,合成了PMMA-b-PSt嵌段共聚物.通过硼氢化钠还原聚合物体系中的溴化亚铜,制备得到纳米铜/PMMA-b-PSt复合粒子.采用红外吸收光谱（IR）、核磁共振（1H NMR）、凝胶渗透色谱（GPC）和透射电子显微镜（TEM）等手段对样品进行表征,并用热分析法对样品的热性能进行了研究.实验结果表明成功合成了以PMMA-b-PSt为壳,以纳米铜为核的复合粒子,并发现这种复合粒子可以形成以PMMA-b-PSt为连续相以纳米铜为分散相的圆环状组装图案,热分析结果表明纳米铜粒子的存在降低了嵌段共聚物的分解温度.     

超声辐照下甲基丙烯酸甲酯本体聚合反应的研究

超声波作为一种新型能源,用以甲基丙烯酸甲酯(MMA)单体的本体聚合反应.研究了超声波频率,超声波辐照时间,超声场温度,引发剂用量对MMA单体转化率的影响.结果表明:该研究范围内,超声波不能直接引发MMA单体产生自由基,进行本体聚合.超声波的频率对MMA单体的转化率有一定的影响,在频率为35 kHz的超声波辐照下,对提高MMA单体转化率的作用最大.随着超声波辐照时间的增加,MMA单体的转化率随之而增大.超声波辐照下,MMA单体的转化率随聚合反应温度的提高而增大.引发剂用量增加,MMA单体的转化率增大.     

聚丙烯酸酯改性聚氨酯胶粘剂的研究

制备了聚酯型聚氨酯／聚丙烯酸酯互穿网络弹性体，将其溶解于溶剂中形成聚氨酯／聚丙烯酸酯粘合剂，考察了丙烯酸酯用量，异氰酸根与羟基摩尔比，催化剂和稳定剂用量，接枝及溶剂等对粘合剂粘合性能的影响，同时考察了粘合剂的储存性能。     

900 MPa级高强钢应变疲劳行为研究

通过应变控制疲劳试验,对1种900MPa级高强钢的循环软硬化行为、循环应变机制及塑性应变能与循环软化的关系进行研究.结果表明：试样的循环软硬化行为随应变幅增加而发生改变,应变幅低于0.3％时,试样主要发生弹性变形,循环行为表现为循环稳定,应变幅为0.4％时,试样的变形行为由弹性变形为主过渡到塑性变形为主,循环行为由循环稳定过渡为循环软化,应变幅高于0.6％时,试样主要发生塑性变形,循环行为表现为循环软化;试样的塑性应变能密度受应变幅的影响且具有循环相关性,应变幅高于0.6％时,试样的塑性应变能密度较高,但随周次变化较小,应变幅低于0.4％时,试样的塑性应变能密度较小,但随周次变化较大;试样的循环软化率随塑性应变能吸收量的增加而提高.     

颗粒增强复合材料的动态压缩力学性能研究

首先采用Instron2300材料试验机和Hopk inson压杆冲击试验测试了10%(vo l)S iC/A l陶瓷颗粒增强金属基复合材料在不同应变率范围的应力应变曲线.结果表明,该复合材料存在明显的应变率强化效应,随应变率的增加,其流动应力也迅速增加.在不相同的应变率下,随应变的增加,复合材料的流动应力与准静态流动应力的比值趋于一常数,表明复合材料在不同的应变率下具有相同的应变硬化规律.最后用R am berg-O sgood材料模型结合应变率强化模型拟合了复合材料的动态应力应变曲线,得到了与实验结果相吻合的结果.     

应变速率对注浆体力学特性影响规律

为研究微震荷载作用下注浆加固体力学特性,以裂隙倾角30°、宽度4 mm的红砂岩裂隙注浆体为研究对象,借助岩石三轴伺服压力机进行变应变速率(10^-5 ~5×10^-3 s^-1)单轴压缩试验;然后从能量耗散、裂纹扩展及破坏形态等3个方面,分析变应变速率对注浆体力学特性的影响规律及机理. 研究表明:随着应变速率的增加,注浆体的峰值强度、弹性模量均随之而增大;且峰值强度与应变速率呈指数函数关系变化;注浆体受应变速率影响的响应分为敏感应变速率阶段和滞缓应变速率阶段,主要差异在于峰值强度变化率和弹性模量变化率;随着应变速率的增大,注浆体的总能量在增大;压密阶段是影响不同应变速率下注浆体力学特性的主要阶段;敏感应变速率阶段和滞缓应变率阶段中的压密阶段主要区别在于积散比大小,积散比进一步决定产生裂纹的多少和分布区域与规律;耗散能密度对注浆体破坏脱落面积以及粒径分布影响较大,耗散能密度越大,碎块越以大块为主(粒径大的比率逐渐增加),滞缓应变率阶段耗散能密度较敏感应变率阶段大,其破碎块体较敏感应变率阶段大. 研究在裂隙注浆加固体的变应变速率影响下力学特性,从能理原理、分形理论角度得到了其影响机理.     

聚甲基丙烯酸甲酯包覆氢氧化镁壳-核粒子的制备

以烷基化氢氧化镁为核，以甲基丙烯酸甲酯为壳层单体，制备聚甲基丙烯酸甲酯包覆氢氧化镁的壳一核粒子。系统研究了烷基化氢氧化镁、引发剂、单体、分散剂、反应温度等因素对无皂乳液聚合反应的单体转化率、产物粒子平均粒径及分散系数的影响。通过重量法测得聚合反应体系的单体转化率．用激光粒度仪测定了产物粒子的平均粒径和多分散系数，运用红外光谱分析，透射电镜等手段对产物进行了表征，证实了壳一核粒子的存在。     

星状pH响应聚合物及其自组装胶束研究

研究了一种星状聚合物——金刚烷基聚己内酯-b-聚甲基丙烯酸二乙氨基乙酯-b-聚甲基丙烯酸单甲氧基聚乙二醇酯（Ad-（PCL-b-PDEAEMA-b-PPEGMA）₄）及其自组装胶束以用于阿霉素（DOX）递送.采用ROP和ARGET ATRP方法合成该聚合物，其自组装胶束具有良好的稳定性（CMC=3.4 mg/L）；DOX负载胶束在pH=5.0下的释放速率明显快于pH=7.4和pH=6.8.结果表明，pH响应Ad-（PCL-b-PDEAEMA-b-PPEGMA）₄胶束可作为抗癌药物靶向递送的潜在载体.     

聚甲基丙烯酸甲酯包覆氢氧化镁壳-核粒子的制备

以烷基化氢氧化镁为核,以甲基丙烯酸甲酯为壳层单体,制备聚甲基丙烯酸甲酯包覆氢氧化镁的壳-核粒子。系统研究了烷基化氢氧化镁、引发剂、单体、分散剂、反应温度等因素对无皂乳液聚合反应的单体转化率、产物粒子平均粒径及分散系数的影响。通过重量法测得聚合反应体系的单体转化率,用激光粒度仪测定了产物粒子的平均粒径和多分散系数,运用红外光谱分析,透射电镜等手段对产物进行了表征,证实了壳-核粒子的存在。     

Preparation of self-crosslinked acrylate emulsion with high elasticity and its rheological properties

Using butyl acrylate（BA）,methyl methacrylate（MMA）,methacrylic acid（MAA） and mixed emulsifier as raw materials,the self-crosslinked emulsion was prepared via pre-emulsified and semi-continuous seeded emulsion polymerization technology in the presence of N-hydroxymethyl acrylamide and poly solidum maleate. The influence of mass ratio of BA to MMA,amount of N-hydroxymethyl acrylamide and poly solidum maleate on the rheological properties of the self-crosslinked emulsion was studied. Possible cross-linked mechanism of self-crosslinked monomer was investigated. And the relationship between emulsion viscosity and shear rate was investigated. The results show that the self-crosslinked acrylate emulsion with high elasticity can be synthesized when the mass fractions of BA is 60%,MMA is 40%,and added amount of N-hydroxymethyl acrylamide is 2.5%-3.0% and added amount of poly solidum maleate is 0.3%-0.4%. The self-crosslinkage process of N-hydroxymethyl acrylamide involves two steps. One is copolymerization of N-hydroxymethyl acrylamide and acrylate,the other is cross-linkage among polymer molecules via condensation reaction of methylol. The emulsion is of rheological properties of pseudo-plastic fluid and belongs to non-Newtonian fluid.     

P(C_9-AA)两亲聚合物制备大颗粒苯丙乳液

研究了以两亲聚合物 P( C9-AA)作乳化剂 ,制备大颗粒及具有一定稳定性的苯丙乳液的方法 ;讨论了乳化剂 ,温度及引发剂用量对乳液性能的影响。结果表明 ,以 P( C9-AA)作乳化剂时 ,乳化剂用量为单体质量的 1 .0 % ,引发剂用量为单体质量的 1 .2 % ,90℃下可以合成性能良好的苯丙乳液     

Effects of stress and physical ageing on nonlinear creep behavior of poly(methyl methacrylate)

The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history,the specimens were quenched and aged at various ageing temperatures for different ageing time,and then the short-term creep tests under different stress levels were carried out at room temperature.The creep strains were modeled by means of time-ageing time equivalence and ti...     

Radial explosion strain and its fracture effect from confined explosion with charge of cyclonite

Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was exploded,two different radial strain waves were sequentially recorded by a strain gage at a distance of 80 mm from the center of charge. Through the attenuation formula of the maximum compressive strain(εrmax), the distribution of εrmax and its strain rate(ε) between the charge and gage were obtained. The effect of the two waves propagating outwards on the radial fracture of surrounding media was discussed. The results show that the two waves are pertinent to the loading of shock energy (Es) and bubble energy (Eb) against concrete surrounding charge, respectively. The former wave lasts for much shorter time than the latter. The peak values of εrmax and ε of the former are higher than those of the latter, respectively.     

温度和应变速率对ZK60镁合金压缩变形行为的影响

在应变量为0.6（ε=0.6）、不同温度（523~723 K）和应变速率（0.001~10 s-1）条件下,利用Gleeble-1500D热模拟试验机,对铸态ZK60镁合金进行热压缩变形行为的研究,分析变形温度和应变速率对ZK60镁合金压缩变形行为的影响规律,即在相同应变速率条件下,随着变形温度的升高,合金的峰值应力降低。在相同温度条件下,随着应变速率的增大,合金的流变应力增大。计算其应变速率敏感指数m值为0.14和表观激活能Q值为226~254 kJ/mol。研究表明,在温度为573~673 K、应变速率为0.001~0.1 s-1时,合金发生动态再结晶。     

Dynamic analysis of fault rockburst based on gradient-dependent plasticity and energy criterion

Fault rockburst is treated as a strain localization problem under dynamic loading condition considering strain gradient and strain rate. As a kind of dynamic fracture phenomena, rockburst has characteristics of strain localization, which is considered as a one-dimensional shear problem subjected to normal compressive stress and tangential shear stress. The constitutive relation of rock material is bilinear (elastic and strain softening) and sensitive to shear strain rate. The solutions proposed based on gradientdependent plasticity show that intense plastic strain is concentrated in fault band and the thickness of the band depends on the characteristic length of rock material. The post-peak stiffness of the fault band was determined according to the constitutive parameters of rock material and shear strain rate. Fault band undergoing strain softening and elastic rock mass outside the band constitute a system and the instability criterion of the system was proposed based on energy theory. The criterion depends on the constitutive relation of rock material, the structural size and the strain rate. The static result regardless of the strain rate is the special case of the present analytical solution. High strain rate can lead to instability of the system.     

常规自由基聚合反应条件下合成PS-g-PMMA的研究

以苯乙烯（St）和对氯甲基苯乙烯（CMS）经常规自由基聚合合成无规共聚物P（St-co-CMS）,再与铜试剂反应合成带有双硫酯结构的聚苯乙烯大分子RAFT试剂。在聚苯乙烯大分子RAFT试剂存在下,进行甲基丙烯酸甲酯（MMA）的常规自由基聚合反应,通过RAFT聚合机理合成接枝共聚物PS-g-PMMA。考察了St与CMS的配比、MMA用量和反应温度对接枝共聚反应的影响。研究结果表明,St与CMS的物质的量比为10∶1、MMA与CMS的物质的量比为80∶1,在60℃下进行接枝聚合,可获得很高的接枝效率和接枝率,分别可以达到60%和75%,而且接枝共聚物的分子量分布相对较窄（-2.1）。     

单轴加卸载条件下岩盐变形过程能量和声发射特征研究 （研究生论坛）

利用 MTS815 Flex Test GT 岩石力学试验系统及声发射(AE)实时监测系统,对取自平顶山和淮安两处矿井的纯盐岩进行了单抽加卸载试验,得到了岩盐的应力-应变加卸载曲线、声发射振铃计数率和能量率曲线,并且从能量与声发射的角度研究了纯岩盐变形破坏过程的基本特征。通过研究表明,岩盐单轴加卸载条件下,弹性变形阶段很短,屈服过程产生很大的塑形变形,且峰后的变形过程没有应力的急剧下降,整个实验过程中加卸、载之间滞回环面积很微小。在整个实验过程中,弹性应变能占的比例非常的小;盐岩单轴加卸载变形破坏过程中,其耗散能随应变一直增加,且增长率递增,而当应力接近峰值时,增长率趋于恒定,耗散能曲线开始呈线性增长;弹性应变能在峰前一直增加,且增长率递减,在峰值处达到最大值,峰后开始下降。岩盐在试验初始阶段振铃计数率与能量率便大量产生,而后在屈服阶段呈现下降进入稳定发展期,直到峰值处,出现一个累计振铃计数和累计能量曲线的拐点,峰后以一个更高的速率稳定地且呈现阶梯状发展。本文对于盐岩储气库的水溶开挖和采气过程中逐渐卸载的应力环境施工过程有一定的实际指导意义。     

Characterization and Saturable Absorption Property of Graphene Oxide on Optical Fiber by Optical Deposition

We prepared graphene oxide(GO) saturable absorber(SA) successfully through optical deposition method, which is a simple but effective approach to deposit various materials onto substrate under the effects of light, and investigated several factors that influence the optical deposition result of GO onto optical fiber end, including poly(methyl methacrylate)(PMMA) concentration, light intensity, light mode, and deposition time. The efficient optically deposited GO preserving its nonlinearity guaranteed by GO/PMMA composite formation was also demonstrated. The GO SA prepared by optical deposition shows superior saturable absorption property with modulation depth and nonsaturable loss of 6% and 40%, respectively.     

分子动力学模拟研究:低聚物在高分子母体中的扩散

采用显式表示氢原子的全原子模型,应用分子动力学模拟,在SGI O2工作站和SGI Origin 200服务器上用Molecular SimulationsInc．(MSI)的Cerius2软件研究甲基丙烯酸甲酯低聚物(聚合度n=i～10)在聚甲基丙烯酸甲酯母体中的扩散现象。结果表明,随着低聚物聚合度的增加,从单聚体到三聚体其扩散系数迅速减小,而从四聚体到十聚体其扩散系数几乎保持不变。而且,通过对模拟获得的扩散系数进行标度,所得结果能够与实验得到的数值符合得很好。对低聚物在高分予母体中的扩散机理进行了探讨,在聚合度很小时(三个以下),低聚物可能以整体迁移扩散为主,而在聚合度稍大时,则以局部蠕动扩散为主。     

中等应变速率对砂岩破坏形态和力学性质的影响

以砂岩为研究对象,根据砂岩的颗粒分析试验、抗压强度、抗拉强度和强度试验结果,在颗粒流程序下,通过fish语言编程,虚拟实现了砂岩数值试件和单轴压缩试验,设计10-3、5×10-3、10-2、2×10-2、5×10-2、10-1、2×10-1s-1这7个应变率下的单轴压缩试验.分析应变率对砂岩破裂形态、裂纹数量和扩展、应力-应变曲线和能量转换的影响.结果发现:应变率的增加破坏了优势剪切带的发展,使得剪切带等速发展,材料由剪切破坏向锥形破坏发展;材料的力学性能表现出极大的伪增强,应力-应变曲线上扬、斜率提高、峰值提高,峰后曲线震荡剧烈;裂缝数量增多,其中拉裂缝减少,剪切裂缝增多;边界输入能量增加,造成加载过程中材料的摩擦能、动能和应变能单调增大,摩擦能增大说明剪切裂缝增多,动能增大说明破坏剧烈,应变能增大说明更容易产生岩爆现象.