高性能高分子材料和高分子设计

高性能高分子材料发展迅速,其发展符合历史的“点～链～片～体”模式。根据已有的高分子科学知识和理论,有目的地设计合成和加工工艺,以满足特定的高性能目标已成为必然趋势。为此,作者提出了若干建议。     

离聚体的结构表征 Ⅲ.EXAFS法测定含氟的铜离聚体的精细结构

本文报道了用先进的EXAFS及ESR等方法研究了羧酸型含氟的铜(Ⅱ)离聚体离子微区的内部精细结构,结果表明,铜离聚体的离子微区主要由羧酸根桥键的双核配位结构单元及平面四方形的配位结构单元等聚集而成。在双核配位结构单元中第一层为Cu~(2+)—O配位,配位数为4,配位键键长为1.96A,第二配位层为Gu~(2+)—Cu~(2+)配位,Cu~(2+)—Gu~(2+)间距为2.64A。平面四方形的配位结构单元Cu~(2+)—O的配位数为4,配位键键长为1.96A。共聚物中羧基含量对离聚体的基本配位结构单元和离子微区的精细结构影响较小,但对微区大小有影响。     

聚合物异核交叉弛豫及二维NOE谱

The heteronuclear cross-relaxation rates in polymers were determined by selective and conventional ~(13)C spin-lattice relaxation experiments, the proton-carbon distances were calculated by the theoretical formula, and two-dimensional NOE spectra of the polymers were also measured. The results showed that (1) the measured proton-carbon distances coincide with the distances from molecular models, (2) there is the observable dipolar cross-relaxation effect between the quaternary carbons and their neighboring protons, and (3) the optimum mixing times depend on the relaxation properties of the proton and carbon.     

端羟丁腈聚氨酯/聚甲基丙烯酸甲酯互穿网络高聚物的T_g和形态研究——Ⅰ.组分比和交联程度的影响

用同步法合成了端羟丁腈聚氨酯/聚甲基丙烯酸甲酯互穿网络高聚物[PU(HTBN)/PMMA-IPN]。用动态力学方法和透射电镜研究了它们的T_(?)转变行为和形态。理论计算和实验结果表明,样品具有两个明显相互分离但又各自连续的相结构,呈现出分属于组分聚合物的两个Tg转变(Tg_1,Tg_2)。在全IPN中,PMMA相区的尺寸(1000—2000?),比在接枝共聚物(3000—6000?)和半IPN(—3000?)中的明显变小。适当的交联程度可使相区进一步变小,变均匀,相连续性增加。这是网络互穿造成的“强迫互容”所致。部分丁腈羟(HTBN)分子同PMMA的反应,使一些样品出现了Tg_2升高的现象。     

天然橡膠的粘-弹性质I.在中温时的本醴粘性流动

1.本實驗採用了Hoeppler平行板塑性計,按照定應力壓縮形變法的理論,在中温時對國產天然橡膠的本體粘性流動進行了流變學研究。 2.在30-90°與250-1500克/厘米～2的荷重範圍內,測定了貌似本體粘度η_a,內切模數G_i與貌似活化能ΔE_η。所測得的G_i=3.30×10～5達因/厘米～2與ΔE_η=12.7千卡/克分子,在一定温度範圍(50-90°)內爲不依賴於温度的常數。對所測天然橡膠估計所得的粘流鰱段長約30個碳原子。 3.從粘性流動的切變速率dγ/dt依賴於切應力σ的關係中,獲得了Eisenschitz早已衍導出的,但迄未在高聚物的本體粘性流動中獲得例證时非牛頓流動流公式。該式復以Saunder及Treloar的數據重加處理而證實之。 4.從切變速率對貌似本體粘度的影響上,檢驗了Debye-Bueche的理論式。現改用單位體積內彈性鍵段計算推遲時間,τ_1=2.84η_0·[J_e]∞,其中穩態彈性柔數[J_e]∞。係由彈性同復實驗測得。經如此處理後,該式在較低切變速率時筒能與實驗結果相符。 5.若以Eisenschitz式與Debye-Bueche式相結合,則亦可計得內切模數G_i,並藉知貌似本體粘度隨切變速率增高而降低的現象,乃係由於發生內切應變γ_i=σ/G_i之故。     

STRUCTURE EFFECTS ON THE SOL FRACTION-DOSE RELATIONSHIP IN RADIATION CROSSLINKING OF POLYMERS

The structure effects of polymers on the relationship between sol fraction and radiation dose arediscussed in detail. In consideration of the deviation of experimental results from Charlesby-Pin-ner's and Chen-Liu-Tang's expressions relating sol fraction to radiation dose, we introduced an ex-ponent βconcerned with the structure and property parameters of a polymer (glass transition tem-perature T_g and molecular internal rotating steric factor δ) and assumed that the fracture density isproportional to R~β(R is radiation dose). Thus, a general expression, formula (9), relating solfraction to radiation dose is derived. When β=1 andβ=0.5, this expression is reduced to the above-said two expressions. Us-ing this general expression, the experimental data of a number of polymers are treated. It is shownthat the expression is in good agreement with the experimental results, βvalue is in the range of 0. 5 to1.0.     

铁体系催化丁二烯聚合的研究——Ⅴ.ESR、NMR和IR研究聚合机理

本文用ESR、~1H-NMR及IR研究了Fe(phen)Cl_3-(i-C_4H_9)_3Al体系催化丁二烯聚合的机理。ESR谱表明,聚合活性中心上的铁为Fe(Ⅱ)。同时观察到自由基的信号,为其还原历程提供了证据。体系中不存在丁二烯时有很宽的ESR信号(ΔH_(pp)=900G)、加入丁二烯时可以观察到一窄信号(ΔH_(pp)=50G),二者有明显区别。提出了Fe(phen)Cl_3-(i-C_4H_9)_3Al体系催化丁二烯聚合的反应机理,两个体系的~1H-NMR和IR谱图的比较证实了这个机理。     

MORPHOLOGY OF POLYBUTADIENE “SHISH KEBABS”

Shish kebab structure of cis-1 , 4-polybutadiene has been obtained by quiescent solution crystallization at suitable temperature. The morphology and growth mechanism of formation of shish kebab structure have been studied in detail.The higher the molecular weight the faster the sample crystallizes.     

FREQUENCY DEPENDENCE OF THE DIELECTRIC RELAXATION OF 1,2-POLYBUTADIENES

The dielectric loss factor and permittivity of a series of 1, 2-polybutadienes with different contents of 1, 2-units and different contents of syndiotactie 1, 2-units were determined over a frequency range from 30Hz to 100KHz at different temperatures. The WLF equation was evaluated for various samples with T_θat 100KHz as a reference temperature and the master curves of various samples have been constructed, which are in accordance with those calculated by Havriliak-Negami equation. The frequency dependence of the dielectric relaxation of 1, 2-polybutadienes was investigated over a frequency range from 10~0 Hz to 10~(12) ZHz in terms of the experimental data and the master curves.     

聚环氧氯丙烷氨酯阻尼材料的阻尼性能研究

<正> 一般来讲,聚合物材料的阻尼性能来源于分子链运动带来的内摩擦力以及分子间物理键的破坏与再生,分子链运动所产生的阻尼在聚合物的玻璃化转变温度范围内最为有效。因此具有极性较强、体积较大的一CH_2Cl侧基的环氧氯丙烷聚合物应具有优异的阻尼性能,专利文献[1—2]报道过由多羟基(官能度≥2)聚环氧氯丙烷预聚物为原料制得的聚氨酯泡沫具有良好的阻燃性能,作者在聚环氧氯丙烷氨酯阻尼材料方面进行了尝试。