丁基橡胶阻尼材料相容性的DSC与DMA研究

高聚物力学阻尼材料是一种能消除振动和噪声以聚合物为基质的功能材料。当聚合物处于玻璃化转变温度(Tg)区域时,其链段运动不能完全跟上振动的速度而产生分子链内摩擦,吸收一部分振动能,再以“热”的形式而耗散,这样就起到减少振幅或降低振幅的作用。     

CIIR/PMAc IPNs阻尼性能

CIIR/PMAc IPNs阻尼性能;氯化丁基橡胶; 互贯聚合物网络; 聚(甲基)丙烯酸酯; 阻尼性能     

聚氨酯/乙烯基酯树脂互穿聚合物网络阻尼性能的研究

采用二步法制备了聚氨酯／乙烯基酯树脂互穿聚合物网络,动态力学分析法研究了ＩＰＮ的阻尼性能。结果表明,聚氨酯／乙烯基酯树脂互穿聚合物网络出现宽温度阻尼范围。当聚氨酯／乙烯基酯树脂＝４０／６０时,材料的宽温度范围的阻尼性能最好。在体系中引入柔性链可改善低温阻尼性能,而引入刚性链则降低阻尼值、提高阻尼温度、阻尼温度范围变窄。在体系中引入大侧基能显著提高聚氨酯／乙烯基酯树脂互穿聚合物网络的阻尼性能,提高交     

P(VA-co-DBM)/PVA乳胶IPN阻尼材料的合成及动态力学性能

用种子乳液聚合法合成了聚（醋酸乙烯酯－co-马来酸二丁酯）／聚醋酸乙烯酯乳胶互穿聚合物网络阻尼材料,动态力学谱结果表明,该阻尼材料在较宽的温域具有很高的阻尼因子。     

聚合物基阻尼材料的结构设计及功能化研究进展

高性能及多功能化是聚合物基阻尼材料研究的重点.本文从聚合物的三维网络结构和微观结构设计角度综述了聚合物基阻尼材料的最新研究进展,包括梯度网络结构、超分子结构、悬挂链结构及轻质多孔结构.此外,总结了聚合物基阻尼材料的自修复、形状记忆和可回收等功能化研究进展,展望了聚合物阻尼材料的发展趋势及面临的挑战.     

PMPS/PMAc相容性与同步互贯聚合物网络的阻尼性能研究

互贯聚合物网络是一种聚合物合金 ,其组分的热力学性质决定组分间的相容性和微相结构 ,从而影响材料的阻尼性能 .采用同步互贯聚合物网络 (SIN)技术制备了一种新型的聚苯基硅氧烷 (PMPS) 聚甲基丙烯酸酯 (PMAc)阻尼材料 ,用DMA和AFM等表征研究了其玻璃化温度转变行为与微观相态结构 .结果表明 ,由相容性好的组分制备的SIN材料阻尼值最高 ,tanδmax 可达 1 4,只有一个玻璃化温度转变峰 ,其微相结构为双相连续 ;组分介于相容与不相容之间时 ,所构成的SIN样品的tanδ≥ 0 3的温度区间最宽 ,可达 170℃ ,微相结构为单相连续 ;由相容性差的组分制得的SIN阻尼材料的内耗峰裂分为两个区间 .PMPS PMAcSIN材料的阻尼性能可以通过调节组分的相容性进行控制 .     

聚环氧丙烷／聚苯乙烯接枝与嵌段共聚物的合成和阻尼性能

合成接枝和嵌段共聚物是研究阻尼材料的重要途径。可以在较广的范围内,调整共聚物的结构,使之具有良好的阻尼性能。我们选择聚环氧丙烷与顺丁烯二酸酐反应,制成端乙烯基大分子单体和遥爪低聚物,与苯乙烯共聚,制成接枝和交联嵌段共聚物。探讨了不同结构因素对阻尼性能的影响规律,研究结果有益于阻尼材料的分子设计。     

交联密度对聚硅氧烷/聚丙烯酸酯同步互穿聚合物网络阻尼材料性能的影响

阻尼性能;交联密度对聚硅氧烷/聚丙烯酸酯同步互穿聚合物网络阻尼材料性能的影响     

胶乳型互穿聚合物网络(LIPN)阻尼材料

详细讨论了LIPN体系的阻尼原理。高分子材料在发生玻璃化转变时,大分子链段在玻璃化转变温度Tg附近的运动可以把振动能转化为热能耗散掉,借此可以达到减振、降噪的目的。这也是LIPN作为阻尼材料的依据。阻尼笥能是分子运动的结果,LIPN组分间的相容性及相互作用是影响阻尼性能的重要因素;采用不同的合成方法,将形成不同的微观形态,也会导致材料阻尼性能的差异。因此本文又深入探讨了各种合成参数及合成条件对体系性能的影响,并且指出了合成过程中特别需要注意的几个问题。     

软段和硬段结构对交联的嵌段共聚物力学阻尼及相容性的影响

本文研究了链段结构对多嵌段共聚物网的相容性及动态力学阻尼性能的影响。分别以端乙烯基低聚物作为软链段,乙烯类聚合物作为硬链段,制备了一系列具有不同链段结构共聚物网。它们在大于50℃的温度范围,能阻尼机械振动。共聚物网中某些软链段和硬链段成分是半相容的。基于这些配方的许多共聚物网,在需要的温度范围,tanδ>1.75。     

Waterborne polyurethanes and their properties

Anionomer-type waterborne polyurethanes (PUs) were obtained from poly(β-methyl-δ-valerolactone) glycol (PMVL) and isophorone diisocyanate, following a prepolymer mixing process. The soft-hard segment phase separation in response to the variations of composition and structure of PU has been studied from the dynamic mechanical measurements of the emulsion cast films. The structural variation included ionic and hard segment content, molecular weight of NCO-terminated prepolymer, and type and length of the soft segment. It was found that phase separation is more sensitive to the soft segment length, rather than the soft segment content. With only phase separation, the rubbery modulus was significant even with lower hard segment content. Phase separation was much more pronounced with PU from poly(tetramethylene adipate) glycol, rather than from PMVL and poly(caprolactone) © 1996 John Wiley & Sons, Inc.     

Synthesis and properties of polycyanoethylmethylsiloxane polyurea urethane elastomers: A study of segmental compatibility

A series of polyurea urethane block polymers based on either aminopropyl-terminated polycyanoethylmethylsiloxane (PCEMS) soft segments or soft segment blends of PCEMS and polytetramethylene oxide (PTMO) were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) chain-extended with 1,4-butanediol. The hard segment content varied from 11 to 36%, whereas the PTMO weight fraction in the soft segment blends varied from 0.1 to 0.9. The cyanoethyl side group concentration was also varied during the synthesis of the PCEMS oligomer. The morphology and properties of these polymers were studied by differential scanning calorimetry, infrared spectroscopy, dynamic mechanical and tensile testing, and small-angle x-ray scattering. These materials exhibited microphase separation of the hard and soft segments; however, attaching polar cyanoethyl side groups along the apolar siloxane chains promoted phase mixing in comparison with polydimethylsiloxane-based polyurethanes. The increased phase mixing is postulated to lead to improved interfacial adhesion and thus can account for the observed improvement in ultimate tensile properties compared with polydimethylsiloxane-based polyurethanes. Both hard segment content and cyanoethyl concentration are important factors governing the morphological and tensile properties of these polymers.     

Investigation on novel thermoplastic poly(urethane-thiourea-imide)s with enhanced chemical and heat resistance

A new generation of segmented thermoplastic poly(urethane-thiourea-imide)s (PUTIs) was synthesized via reaction of polyethylene glycol and thiourea-based prepolymer with dianhydride as chain extenders. NCO-terminated prepolymer was synthesized from a new diisocyanate, 3-(3-((4-isocyanatophenyl)carbamoyl)thioureido)phenyl-4-isocyanatophenylcarbamate (IPCT), as a hard segment and PEG forming soft segment. The starting materials and polymers were characterized by conventional methods and physical properties such as solubility, solution viscosity, molecular weight, thermal stability and thermal behavior were studied. PUTIs showed partially crystalline structures. Weight average molecular weights of PUTIs (GPC measurements) were in the range of 1,68,694-1,97,035. Moreover, thermogravimetric analysis indicated that poly(urethane-thiourea-imide)s were fairly stable above 500 °C having T₁₀ of 521-543 °C. Investigation of the results authenticated the approach of introducing thiourea (using IPCT) and imide structure in polyurethanes for the improvement of thermal stability. In comparison to typical polyurethanes, these polymers exhibited better heat resistance, chemical resistance as well as processability.     

丁基橡胶的阻尼减振性能

丁基橡胶玻璃化转变区的特殊蠕虫状分子运动形式,使其具有优异的力学阻尼特性。利用高聚物阻尼性能,采用约束阻尼层及自由阻尼层结构处理方式进行减振与降噪已有大量的文献报导,并且近年来已发展成为一个新的学科。本文报导了丁基橡胶硫化胶及其石墨填充体系的力学阻尼性能和采用衬套结构形式的减振效果。     

Poly(urea)urethanes based on amorphous quaternizable hard segments and a crystalline polyol derived from castor oil

A set of poly(urea)urethanes (PUU), with different contents of amorphous hard segment and castor oil-derived crystalline polyol as soft segment, was prepared combining bulk and solution polymerizations. It is shown that both the soft segment crystallinity and hard segment glassy nature control the stiffness of the materials and that phase mixing at intermediate hard segment compositions produces softer materials. Upon yielding, PUU developed large plasticity associated to the nature of soft segments. At longer strains, PUU presented strain-induced crystallization related both to soft segments alignment and crystallization, leading to strong and tough materials, especially with high hard segment content compositions. Despite the hydrophobicity of the soft segments, the PUU with 65 wt% hard segment content was dispersable in water after quaternization with acetic acid. The high amount of urea groups in this quaternized PUU makes one think of these types of polymers as promising water soluble environmentally friendly strong adhesives, coatings, or water soluble polymeric electrolites.     

多嵌段聚醚-酯共混物的微相结构与血液相容性研究

本工作合成了两种性质不同的聚醚-酯多嵌段共聚物,一种是以聚对苯二甲酸乙二酯为硬链段,聚乙二醇(PEGT)为软链段的亲水性多嵌段共聚物,另一种是以聚对苯二甲酸乙二酯为硬链段,聚四亚甲基醚二醇(PTMGT)为软链段的疏水性多嵌段共聚物。将两种共聚物以一定的比例共混,制备多嵌段聚醚-酯共混物。 改变共混物的组成,研究其微相结构与血液相容性的关系。采用动态力学谱(VES)、示差扫描量热(DSC)、透射电镜(TEM)和扫描电镜(SEM)等测定共混物的微观结构,采用微球柱法评价共混物的血液相容性。实验结果表明:材料的微观非均相结构及亲水平衡是决定血液相容性的重要因素。     

Synthesis and Characterization of Novel Segmented Polyionenes Based on Polydimethylsiloxane Soft Segments

Novel polydimethylsiloxane (PDMS) based polyionenes were synthesized by a modified Menschutkin reaction involving reaction between bromo-terminated PDMS oligomers and various ditertiary amino compounds. In this study, the nature of the hard segment was varied by using various ditertiary amino compounds and in some cases by incorporating chain extenders, while the soft segment content was varied by changing the molecular weight of the PDMS oligomers. The mechanical properties of these materials were found to be dependent on both the nature and amount of the hard segments. These materials also showed distinct evidence of a microphase-separated morphology where under normal conditions, the hard segments formed in what are believed to be cylindrical ion-rich microdomains dispersed randomly in the soft PDMS matrix. When subjected to uniaxial deformation, the ionic cylinders were found to orient along their long axes in the stretch direction.     

长软链段对苯二甲酸乙二酯-环氧乙烷多嵌段共聚物的组成不均一性研究

合成了不同软链段长度和不同硬链段含量的系列对苯二甲酸乙二酯－环氧乙烷(PET-PEO)多嵌段共聚物,用NMR质子港测定了硬链段含量,对部分溶于氯仿的PET－PEO多嵌段共聚物进行了分离,并分别测定其氯仿可溶物和不溶物的硬链段含量、熔融热谱和热结晶谱.揭示了PET－PEO多嵌段共聚物的组成不均一性及其对软镇段长度和硬链段含量的依赖性,进而用DSC热谱证明了软链段和硬链段的结晶能力与PET－PEO多嵌段共聚物组成不均一性密切相关.     

Characterization of Novel Biodegradable Segmented Polyurethanes Prepared from Amino-Acid Based Diisocyanate

Segmented polyurethanes (SPUs) which were expected to yield non-toxic degradation products were synthesized from lysine-based diisocyanate (LDI), 1,3-propanediol (PDO), and polycaprolactone diol (PCL). SPUs were synthesized via a standard two-step prepolymer method. The hard segment fraction was changed in order to tune the mechanical properties and the degradability. The aggregation structures of the SPUs were characterized by infrared spectroscopy and differential scanning calorimetry (DSC), temperature dependence of dynamic viscoelasticity, and small-angle X-ray scattering (SAXS). DSC and dynamic viscoelastic measurements revealed that the glass transition temperature (T_g) of the soft segment increased with an increase in the hard segment fraction. SAXS of SPUs revealed the aggregation states of hard and soft segments. Furthermore, the degradation of SPUs was investigated by exposing the polymers to a buffer solution at 310 K (pH=7.6). The degradation rate of SPUs increased with an increase in the soft segment fraction. This is because the soft segment has the hydrolyzable ester linkages and the ester linkages are susceptible to hydrolysis compared with the urethane linkages. Finally, an electrospray deposition method was used to fabricate biodegradable SPU micro-fibers. FE-SEM images showed that higher concentration of solution favored the formation of uniform biodegradable micro-fibers without beads-like structure.