纳米碳酸钙改性PVC/PP共混体系的研究

用目前研究较多的纳米材料———纳米碳酸钙(Nano CaCO3)对PVC/PP共混体系进行改性后,再利用扫描电子显微镜(SEM)和能谱仪(EDS)观察共混物各相相容性及其对力学性能的影响。结果表明:将纳米碳酸钙引入PVC/PP共混体系后,共混物两相的相分离度降低并且力学性能也有了明显的改善;并且发现共混物力学性能的变化与其相态结构的改变存在着一定的关系。     

小分子增塑剂对聚氯乙烯共混体系相容性的影响

采用熔融共混法分别将聚氯乙烯(PVC)、增塑剂邻苯二甲酸二辛酯(DOP)和α-甲基苯乙烯-丙烯腈共聚物(α-MSAN)或聚甲基丙烯酸甲酯(PMMA)进行熔融共混,制备了一系列PVC/α-MSAN/DOP和PVC/PMMA/DOP共混物,利用动态黏弹谱仪、扫描电子显微镜研究了共混体系的相容性和相形态。结果表明,PVC/α-MSAN和PVC/PMMA共混物均为完全相容体系,引入增塑剂DOP后,PVC/PMMA共混物仍为相容体系,而对于PVC/α-MSAN共混物,随着DOP含量的增加,共混体系的相分离愈趋明显;最后阐明了小分子化合物对聚合物共混体系相容性的影响机制。     

PS/PE-g-MAH及PS/PE相容性评价的分子动力学模拟

采用分子动力学(MD)模拟方法对比研究了聚乙烯(PE)与聚苯乙烯(PS)共混体系和力化学反应法马来酸酐接枝聚乙烯(PE-g-MAH)与PS共混体系的相容性。通过对MD模拟得到的溶解度参数、玻璃化转变温度、径向分布函数和均方末端距的分析,对两种共混物的相容情况进行评价。研究表明,PS/PE体系的共混相容情况不好,而PS/PE-g-MAH体系相对于PS/PE体系,相容性得到明显改善。模拟结论与实验结果相一致。     

无定型高聚物共混物的相容性研究——反相色谱法

本文通过反相色谱法测定PS/PMMA,PS/PVC,以及PS/P(S-co-α-MeS)共混物等样品的Tg来判断其热力学相容性的情况,结果前两对共混物测得两个Tg为热力学不相容体系,后者只测得一个Tg为热力学相容体系。并且与DSC等法进行对比,证明上述反相色谱法对共混物相容性的研究有着较高的灵敏度。     

SEBS弹性体增韧改性PE-HD/PS共混物及其相容性研究

采用聚苯乙烯嵌段聚（乙烯亚丁基）嵌段聚苯乙烯（SEBS）弹性体增韧改性高密度聚乙烯（PE-HD）/聚苯乙烯（PS）共混物,通过哈克转矩流变仪制备了PE-HD/PS/SEBS三元共混物,采用扫描电子显微镜（SEM）、旋转流变仪、冲击试验机、热重分析仪（TG）和差式扫描量热仪（DSC）等手段研究了PE-HD/PS/SEBS共混体系的相容性。结果表明,SEBS对共混体系具有良好的增容作用,但当SEBS添加量大于8 %(质量分数,下同)后,部分SEBS出现团聚现象,导致共混体系相容性降低;SEBS的引入对共混物的耐热性影响不大,共混物中连续相PE-HD的熔点稍有降低;随着SEBS添加量的增加,共混物的悬臂梁缺口冲击强度大幅提高。     

超支化聚（酰胺-酯）／ABS／聚氯乙烯共混体系相容性研究

研究了超支化聚(酰胺-酯)(HBP)对ABS/聚氯乙烯(ABS/PVC)共混体系的增容作用。讨论了HBP用量对ABS/PVC(80/20)和相同量HBP对不同比例ABS/PVC力学性能的影响。实验结果表明ABS/PVC共混物中加入HBP,可以有效改善共混体系的相容性;加入2份HBP时,ABS/PVC(80/20)共混物拉伸强度达到最大值,继续增加HBP,共混物拉伸强度快速下降,而共混物冲击强度单调下降;不同比例ABS/PVC中加入2份HBP共混物拉伸强度比未加入HBP共混物拉伸强度增加,但共混物冲击强度减小。扫描电子显微镜研究结果证明了HBP增强了ABS/PVC的界面黏结作用,减小了共混体系的相分离程度。     

拉曼Mapping成像研究聚苯乙烯/聚甲基丙烯酸甲酯共混体系的相态结构

利用拉曼光谱成像技术研究了聚苯乙烯/聚甲基丙烯酸甲酯（PS/PMMA）共混薄膜体系及其增容体系（增容剂为PS-b-PMMA嵌段共聚物）的相态结构及化学成分分布。实验结果表明,拉曼Mapping成像技术不仅可以得到PS/PMMA共混体系化学成分的精确分布图,同时也可以获取共混体系中分散相、界面相和连续相的分子指纹光谱。研究发现,共混体系中分散相和连续相组分分布与体系的组成紧密相关,当PS/PMMA质量比30/70时,分散相为PS,连续相为PMMA;当PS/PMMA质量比为50/50时,分散相为PS,但PS分子链仍存在于PMMA连续相中;当PS/PMMA质量比为70/30时,分散相为PMMA,连续相为PS。当增容剂PS-b-PMMA加入到PS/PMMA共混体系中后,分散相粒径减小、分布更加均匀、共混体系相容性指数（N_c）增大,说明PS/PMMA共混体系由完全不相容体系趋向变成半相容性体系,这是因为增容剂能增加PS和PMMA之间的相互作用,降低了体系的相分离程度,改善了共混体系的相容性。     

2005年中国聚苯乙烯研发与应用论文题录

蒙脱土改善PVC／PS共混物相容性的研究,利用废弃聚苯乙烯泡沫塑料生产涂料的研究,利用表面接技反应控制PS亲水性能，HIPS和PE-LD阻燃特性的研究,溴锑阻燃体系对PS—HI.     

新型相容剂的合成及应用研究

合成了接枝率分别为86%和20%的两亲性超支化聚(胺-酯)(A-HPAE),并研究了其对PVC/PP共混体系的增容作用。讨论了A-HPAE的用量和接枝率对PVC/PP共混体系力学性能的影响。实验结果表明,在PVC/PP共混物中加入接枝率为86%的2份A-HPAE时能很好改善共混体系的相容性,使共混物拉伸强度和断裂伸长率达到最大值;氯元素的X射线能谱微区分析研究结果证明A-HPAE提高了共混物两组分间的相容性。     

高能辐射对HDPE/PS/PVC共混体系的增容增韧作用( 英文)

适用于二元体系的增容剂EVA和SEBS对三元体系的增容、增韧作用不明显,对HDPE/PS/PVC共混体系进行γ-射线辐照,使得体系相容性提高,抗冲击性能显著提高,断裂伸长率略有下降。照射产生的相互交联是增容、增韧的主因。     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.     

Synthetic routes to nanoscale BxCyNz architectures

B_xC_yN_z nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC₂N, BN, BC and CN_x systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources.     

Structure Evolution from Pb(Mg1/3Nb2/3)O3 to La(Mg2/3Nb1/3)O3

The crystal structure of lanthanum-modified lead magnesium niobates having composition (Pb_{1− x} La _x ) (Mg_{(1+ x )/3}-Nb_{(2− x )/3})O₃ with X = 0 to 1 was investigated by X-ray powder diffraction. It was found that the fundamental reflections from perovskite structure remain in the whole range of composition. The superlattice reflections from the A(B'_1/2-B"_1/2)O₃ ordered structure are also well preserved for La content greater than 50 at.%; however, a series of extra peaks of mixing indices appears, with intensities gradually enhanced with the increase of La content. For the complete substitution of Pb by La, a splitting of some reflections can be observed in the diffraction pattern. The results indicate that the crystal structure evolves continuously with the La content, from disordered cubic perovskite of space group Pm 3 m for X = 0, to ordered cubic perovskite of space group Fm 3 m for X = 0.5, distorted cubic perovskite of space group Pa 3 for 0.5 < X < 0.9, and finally to a rhombohedral perovskite, possibly belonging to the space group R 3 , for X ≥ 0.9. In the evolution of structure, a linear reduction of the lattice constant of the perovskite cell from 4.048 to 3.964 Å was observed.     

(Bi1/2Na1/2)TiO3–Ba(Cu1/2W1/2)O3 Lead-Free Piezoelectric Ceramics

(Bi_1/2Na_1/2)TiO₃ with 0–6 mol% Ba(Cu_1/2W_1/2)O₃ (BNT-BCW), a new member of the BNT-based group, has been prepared following the conventional mixed oxide route. The compacted bodies were sintered at 1130°C for 2 h to get dense ceramics. The addition of BCW into BNT ceramics facilitated the poling process because of a reduction in leakage current. 0.995BNT·0.005BCW ceramics exhibit a relatively high piezoelectric constant ( d ₃₃= 80 × 10⁻¹² C/N) and a relatively low dielectric loss (tan δ= 1.5%). Increased amount of BCW was found to increase the dielectric constant and loss of BNT-BCW ceramics and to suppress the grain growth. During sintering, some BCW diffuses into the lattice of BNT to form a solid solution and some remains on the grain boundaries.     

炭黑/煤矸石/碳纳米管复合填料体系对天然橡胶性能的影响研究*

利用硝酸氧化法对碳纳米管(CNTs)进行纯化,并用环氧天然橡胶(ENR)进行改性处理。结合胶质量分数测定结果表明, ENR用量15%(质量)时效果最佳。采用胶乳凝聚法制备CNTs/天然橡胶(NR)母料。煤矸石粉(CG)经高温煅烧和表面改性处理。 将CNTs/天然橡胶(NR)母料、CG和炭黑(CB)通过机械混炼法与天然橡胶及配合剂混合,制备CB/CG/CNTs/NR复合材料,并对复合材料进行硫化特性及物理机械性能。结果表明： CNTs延迟硫化效应明显;相比炭黑,CG对硫化具有促进作用。硫化特性和甲苯溶胀法测定结果表明,在填料份数相同的条件下,单独由CB填充的NR有最大的交联密度,CNTs对交联密度影响不明显。物理机械性能测试结果表明,当CG：CB：CNTs=17.5:16.5:1(Phr)时,NR硫化胶的300%定伸应力和扯断伸长率明显高于单独由CB填充NR,而拉伸强度与之接近,复合填料样填充NR具有较好的综合性能。扫描电镜测试结果表明,复合填料在NR基体中分布均匀。     

Dielectric-State Analysis in Solid-Solution Pb(Yb1/2Ta1/2)O3–Pb(Lu1/2Nb1/2)O3

The structure and temperature dependence of complex lead perovskite dielectrics were investigated for the system (1 − x )Pb(Yb_1/2Ta_1/2)O₃– x Pb(Lu_1/2Nb_1/2)O₃. Superlattice reflections for the compositions 0.8 < x < 1.0 were observed by X-ray diffractometry, and the temperature-composition dielectric-state diagram was determined. In the present study, the disordered middle composition, with 0.2 < x < 0.8, showed a diffuse paraelectric–ferroelectric phase transition, whereas the ordered end compositions, with 0 ≤ x < 0.2 and 0.8 < x ≤ 1.0, revealed successive sharp paraelectric–antiferroelectric and weak antiferroelectric–ferroelectric phase transitions. The dielectric state was confirmed by examining the variation of polarization ( P ) with electric field ( E ).