尼龙11的力学松弛与结构变化EI

在 - 18 0℃～ + 180℃的范围内测试了尼龙 11的动态力学性能 ,讨论了拉伸和退火处理对尼龙11力学松弛过程的影响。α松弛峰表征尼龙 11非晶区中链段的松弛运动 ,样品结晶度的增加使模量 E′降低 ;β松弛峰与羰基的运动有关 ,经过干燥的样品 ,β峰几乎消失 ;γ松弛峰是分子链中亚甲基协同运动引起的。尼龙 11的弹性模量随温度升高而下降 ,但由于氢键的作用 ,尼龙 11在低于 180℃时仍具有较好的热态力学性能。     

尼龙1212动态力学性能的研究

通过动态力学性能分析,对尼龙1212的松弛与转变进行了研究,确定了尼龙1212的松弛转变峰。65℃的松弛峰为尼龙1212的α松弛峰;-35℃出现的松弛峰为尼龙1212的β转变峰,-116℃出现的松弛峰是尼龙1212的γ转变峰。在不同的实验条件下,随着退火温度的升高,尼龙1212的α转变峰的峰高升高,而β转变峰的峰高降低;随测试频率的提高,尼龙1212的α转变峰、β转变峰和γ转变峰向高温移动。     

长碳链尼龙1111的动态力学性能

通过动态力学性能分析,确定了尼龙1111的松弛转变峰。71℃的松弛峰为尼龙1111的α松弛峰;-45℃出现的松弛峰为尼龙1111的β转变峰,-126℃出现的松弛峰是尼龙1111的γ转变峰。在不同的实验条件下,随着退火温度的升高,尼龙1111的α转变峰的峰高升高,γ转变峰的峰高降低,β转变峰的峰高不但降低,而且峰宽度变大;随测试频率的提高,尼龙1111的α转变峰、β转变峰和γ转变峰向高温移动。     

尼龙11室温以上分子链运动的介电松弛研究

通过熔融后冰水淬火和热处理方法制备了δ'晶型和α晶型的尼龙11薄膜试样.在42Hz～5MHz频率范围测得了室温至150℃的介电松弛频率谱,研究了二种晶型的尼龙11在室温以上的分子链运动.结果发现,尼龙11在δ'→α晶型转变之后,由HavriliakNegami经验公式拟合得到的分子链段和局域运动的松弛强度都减小,松弛时间则增大,表明退火之后尼龙11的分子链运动受到了抑制.     

不同结晶度尼龙1010的分子链段运动与电荷存储输运

用在不同温度下热处理的方法制备了具有不同结晶度的尼龙1010试样,通过测量热释电流研究了试样的分子链段运动与电荷存储输运特性.热释电流谱上显示两个电流峰,通过研究峰电流与极化场强的关系发现,62℃左右的α峰为偶极松弛峰,109℃左右的ρ峰为空间电荷峰.随着结晶度从0.05%增加到46.3%,尼龙1010的偶极松弛活化能由0.98增加到1.18eV,显示分子链段运动变得困难;陷阱深度则变浅,由1.36降低到1.13eV,表明适当的结晶度可提高对载流子的俘获能力,改变材料中电荷的存储与输运特性.     

尼龙11/POE共混物的形态与力学性能

采用动态力学分析(DMTA)和扫描电镜(SEM)等方法研究了相容剂乙烯辛烯共聚物接枝马来酸酐聚合物(POE-g-MAH)对尼龙11(PA11)共混体系力学性能及共混物形态的影响。结果表明,混合弹性体中m(POE-g-MAH)/m(POE)=2∶1时,PA11共混物的缺口冲击强度达到81.2 kJ/m2;共混物缺口冲击强度对MAH接枝率敏感;加入混合弹性体,共混体系分子间的作用力增大,损耗峰向高温方向移动,Tg升高;PA11与POE各个共混体系的β松弛峰高显著低于纯PA11的,加入POE和POE-g-MAH可有效降低PA11的吸水性;POE-g-MAH可显著改善PA11/POE共混材料的相容性,使分散相尺寸减小,分布均匀,且材料缺口冲击强度显著增大。     

尼龙612的结晶及熔融行为

用X射线衍射(WAXD)研究了尼龙612的晶型转变,低温下结晶得到尼龙612的β晶型,随结晶温度的升高,β晶型转变为α晶型。通过差示扫描量热(DSC)对尼龙612的熔融行为进行了研究,尼龙612样品经过不同的热处理后,其熔融行为发生较大的变化,出现了两个熔融峰,低温熔融峰与退火温度相近。在熔融过程中,当温度升高到退火温度时即发生熔融,出现一熔融峰。     

尼龙66/聚酚氧树脂共混体系的相容性EI北大核心CSCD

针对尼龙66与聚酚氧树脂共混体系的相容性展开研究。将尼龙66与聚酚氧树脂以不同配比进行熔融共混,使用动态力学分析仪测定共混样品中两个组分的玻璃化转变温度,使用差示扫描量热仪测定共混样品中尼龙66组分的熔点和结晶度,并且根据Nishi-Wang方程计算共混体系中尼龙66与聚酚氧之间的相互作用参数,以此分析尼龙66与聚酚氧树脂之间的共混相容性。研究发现,聚酚氧分子链中的羟基与尼龙66分子链中的酰胺基团之间的氢键作用使尼龙66与聚酚氧部分相容;聚酚氧在尼龙66相中的部分溶解造成PA66组分的玻璃化转变温度上升;由于尼龙66与聚酚氧之间的氢键对聚酚氧链段运动的束缚作用强于尼龙66的链柔性对聚酚氧链段运动的促进作用,尼龙66在聚酚氧相中的部分溶解导致聚酚氧组分的玻璃化转变温度不降反升。随着聚酚氧含量增加,共混物中尼龙66的结晶熔点和结晶度均随之下降;共混体系中尼龙66与聚酚氧的相互作用参数为负值,但共混体系呈现"海-岛"两相结构。     

尼龙66/聚酚氧树脂共混体系的相容性

针对尼龙66与聚酚氧树脂共混体系的相容性展开研究。将尼龙66与聚酚氧树脂以不同配比进行熔融共混,使用动态力学分析仪测定共混样品中两个组分的玻璃化转变温度,使用差示扫描量热仪测定共混样品中尼龙66组分的熔点和结晶度,并且根据Nishi-Wang方程计算共混体系中尼龙66与聚酚氧之间的相互作用参数,以此分析尼龙66与聚酚氧树脂之间的共混相容性。研究发现,聚酚氧分子链中的羟基与尼龙66分子链中的酰胺基团之间的氢键作用使尼龙66与聚酚氧部分相容;聚酚氧在尼龙66相中的部分溶解造成PA66组分的玻璃化转变温度上升;由于尼龙66与聚酚氧之间的氢键对聚酚氧链段运动的束缚作用强于尼龙66的链柔性对聚酚氧链段运动的促进作用,尼龙66在聚酚氧相中的部分溶解导致聚酚氧组分的玻璃化转变温度不降反升。随着聚酚氧含量增加,共混物中尼龙66的结晶熔点和结晶度均随之下降;共混体系中尼龙66与聚酚氧的相互作用参数为负值,但共混体系呈现"海-岛"两相结构。     

纳米SiO_2的均匀分散及其对MC尼龙6晶型结构及晶型转变的影响

通过阴离子开环聚合法制备纳米二氧化硅(Si O2)/MC尼龙6原位复合材料,采用透射电子显微镜(TEM)对纳米粒子在基体中的分散行为进行表征,结果表明Si O2约以30～70nm左右的尺寸均匀分散在基体中。广角X射线衍射(WAXD)结果表明,纯MC尼龙6及其原位复合材料均呈现典型尼龙6的α晶型衍射峰,纳米Si O2的引入在MC尼龙6结晶过程中削弱了大分子链在c轴的取向。液氮淬冷样品经退火处理后的WAXD结果表明,纳米Si O2和MC尼龙6之间的相互作用阻碍了大分子链段的运动,从而使得γ晶型向α晶型的转变速率降低。     

Probabilistic strength of {1 1 1} n-type silicon

The two-parameter Weibull strength distribution of {1 1 1} n-type silicon prismatic bars was determined in four-point bending and analyzed as a function of specimen size (width), loading rate, two different crystallographic orientations, and specimen orientation (polished or etched surface in tension). 100% fractography was performed to classify strength-limiting flaw types and to censor the strength data. All flaw types were extrinsic. Machining or cutting damage in the form of chipped edges (an edge-type flaw) was the dominant strength-limiting flaw when the polished surface was subjected to tensile stress, while a flat-bottomed etch pit (a surface-type flaw) was the dominant strength-limiting flaw when the etched surface was subjected to tensile stress. The censored Weibull strength distribution was independent of specimen width, loading rate (indicative of slow crack growth insusceptibility), and the two crystallographic orientations; however, it was dependent on specimen orientation. Pooling of the strength data was employed to tighten the confidence intervals about the censored parameters. The results from this study indicate that different extrinsic strength-limiting flaws and strength distributions will be operative depending on the manner in which a silicon component is stressed.     

Diffusion of clusters down (1 1 1) aluminum islands

The key factor determining nucleation processes and faceting in homoepitaxial growth as well as texture competition is the mobility of adatoms and small clusters across step edges and facets. Using a combination of molecular dynamics and ab initio calculations, we investigate the mechanisms of small clusters (dimer and trimer) diffusion down the aluminum (1 1 1) surface. In this paper we report results of molecular dynamics studies. Our study shows that the clusters dissociate at the step-edge of compact islands. As a result, the clusters diffuse down the step by an exchange mechanism with a small or medium Schwoebel barrier. The mechanism of this down-diffusion/dissociation is discussed and the corresponding energetics are calculated using the molecular statics method. We find a large anisotropy between the barriers at the two types of 1 1 0 oriented steps.     

Chemical etching of {1 1 1} and {1 0 0} surfaces of InP

The effects of a number of chemical etches on the III–V semiconductor InP were studied, using {1 0 0} and {1 1 1}-type faces. The (1 1 1) and (¯1¯1¯1) faces were found to behave differently, and this was attributed to the polarity of the zinc-blende lattice. Curves showing etching rate as a function of penetration were plotted, and it is noted that they demonstrate an enhanced etching rate close to the surface. This is attributed to the damaged surface layer associated with the cutting of a crystal slice. Photographs were taken at various stages of the etching using both the optical and scanning electron microscopes. Both etch pits and etch hillocks were observed. The shapes of the pits are compared to those described in previously published work, and possible reasons for these shapes are discussed. The conditions necessary for the production of an etch hillock are described and it is shown that the measured etching rates are consistent with hillock formation in the case of the 1 HCl1HNO₃ etch. The mechanisms of dissolution are discussed and it is suggested that both activation control of the dissolution process and diffusion control were observed in the work.     

1—3型压电复合材料圆柱形水听器

通过对圆柱形水听器在低频接收时的静态理论分析,得到了1－3型压电复合材料径向极化圆柱形水听器的自由场电压接收灵敏度计算公式;分析了不同背衬材料及不同厚度的复合材料对圆柱形水听器灵敏度的影响;实测了1－3型压电复合材料圆柱形水听器的自由场电压接收灵敏度。试验值与理论计算值基本吻合。     

Checking of DIIV-1, DINIR-1, and DINS-1 instruments

Conclusions As follows from what has been said, the amount of specific measurements during the checking of DINIR-1 and DINS-1 instruments is quite large. Taking into account the constant addition to the inventory of these instruments as they are being produced, it is desirable, in the authors' opinion, to consider the problem of developing and subsequently producing a special instrument intended for the checking of various types of time interval meters.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 77–81, June, 1971.     

Transmission electron microscope study of the topotactic reaction of (0 0 1), (0 1 1) and (1 1 1) Ag films and Te

The formation, structure and morphology of silver telluride was investigated in the reaction of (0 0 1), (0 1 1) and (1 1 1) single crystalline Ag films with vacuum deposited Te. Silver films 30–40 nm in thickness were deposited by thermal evaporation onto water- and chlorine-treated NaCl. Onto this silver 1–40 nm of tellurium were deposited at 100 and 200 °C. The Ag–Te reaction occurred during Te deposition. Accordingly, formation of the compound phase was investigated from the nucleation stage through complete tellurization on either side of the polymorphic phase transformation temperature (T_c=150 °C). Transmission electron microscope and selected area electron diffraction showed that monoclinic silver telluride (Ag₂Te) of different morphology and texture was always formed. The orientation of silver and monoclinic phase upon differently oriented monocrystalline Ag films and at deposition temperatures around T_c is discussed.     

Hydriding behavior in Ca/1bMg/1bNi/1bB

Hydriding behavior (thermodynamic, kinetic and structural data) of selected materials in Ca/1bMg/1bNi/1bB is reported. A number of new hydrides is established including CaNi₂H_3.4, CaNi₃H_4.6 and CaNi₄BH_3.8. Mg substitutes for Ca in CaNi₂ within a broad homogeneous range. This leads to a reduction in the rate as well as amount of hydrogen uptake. The reduction in the hydriding rate yields crystallographically better defined hydride phases. Most hydrides based on Ca react violently with water yielding fine particles of Ni, H₂ and Ca(OH)₂. CaNi₅H₆ is found to show decomposition reactions both in the hydriding process as well as on storage over extended periods of time (of order a year).