FRS-XRSA表征双轴取向聚对苯二甲酸乙二酯薄膜的取向分布

Ｘ－射线散射理论分析（ＦＲＳ－ＸＲＳＡ）是作者为了研究和表征取向高聚物结晶度与晶粒取向分布（ＯＤＣ）的一种新方案．在表征ＯＤＣ方面应用分峰法（ＣＰＲ）消除了传统极图法（ＰＦＭ）中高重叠峰相互干扰的困难，克服了取向分布函数分析（ＯＤＦＡ）中出现虚织构的困难，并且经一次系统的ＦＲＳ－ＸＲＳ测定，可以得到几乎所有主要（ｈｋｌ）晶面法向的ＯＤＣ．作者应用ＦＲＳ－ＸＲＳＡ对二类双轴取向ＰＥＴ磁带薄膜进行了ＯＤＣ的研究。基于结晶几何学原理（ＣＧＰ），建立了三斜晶系晶粒坐标系与试样坐标系的关系，并用于推演未测定方位角（αｉ，βｉ）（ｈｋｌ）的晶面散射以及未测（ｈ′ｋ′ｌ′）晶面的ＯＤＣ．作者关系建立了双轴取向函数〈ｃｏｓ２φｈｋｌ，ｉ〉，ｉ＝Ｎ、Ｍ、Ｔ的计算公式．按照ＦＲＳ－ＸＲＳＡ获得了反映取向分布的１０个晶面的双轴极图、三个主晶面（１００）、（０１０）、（１０５）的总极图，以及反映平均取向的各种取向函数，如〈ｃｏｓ２φｈｋｌ，ｉ〉、ｆｃｈｋｌ，ｉ等，结果十分令人满意．     

FRS—XRSA与SAXS研究硬弹性聚丙烯的结晶度,取向与超结构：Ⅲ.应变与回复

应用全倒易空间Ｘ－射线散射理论分析（ＦＲＳ－ＸＲＳＡ）与ＳＡＸＳ研究了ＨＥＰＰ在应变（ε）与回复（Ｒ）过程中结晶、取向与超结构的变化。结果指出，ε可以诱发结晶，但当ε≥３０％后，结晶度（ＸＣ＾Ｗ）趋于不变：ε可以导致晶粒破碎；ε与Ｒ对取向分布与平均取向基本上无影响，这符合片晶平行分离模型，而非叶簧弯曲模型；发现，在ε≤３０％时，层状片晶的分离为主要过程，而当ε〉３０％后，则分离的片晶会发生断层滑移     

辐照异相成核结晶PA1010体系的ESR研究——结晶表面积对俘陷自由基的影响

本文通过ＷＡＸＤ，ＤＳＣ方法讨论成核剂（Ｎｄ２Ｏ３）对ＰＡ１０１０的聚集态结构的影响。用ＥＳＲ研究辐照不同聚集态结构ＰＡ１０１０体系的俘陷自由基行为。结果表明：俘陷自由基—ＣＨ２ＣＯＮＨＣＨＣＨ２—主要存在于结晶表面，结晶的表面积越大，俘陷自由基—ＣＨ２ＣＯＮＨＣＨＣＨ２—的含量越高，在一定条件下，如升温，常温放置一段时间，转化为俘陷自由基—ＣＨ２Ｃ＝Ｏ的量也越大；俘陷自由基－ＣＨ２Ｃ＝Ｏ主要存在于非晶区。     

弹性体型聚氨酯和聚碳酸酯共混物的形态结构

用ＤＳＣ、ＷＡＸＤ和ＳＡＸＳ研究了溶液共混的弹性体型聚氨酯（ＰＵ）／聚碳酸酯（ＰＣ）共混物的结构。结果表明，ＰＵ／ＰＣ为部分相容体系；共混过程中，溶剂ＤＭＦ的诱导作用使ＰＣ形成结晶，其长周期与ＰＵ硬段形成微相的长周期相近     

FRS-XRSA与SAXS研究硬弹性聚丙烯的结晶度、取向与超结构Ⅲ应变与回复

应用全倒易空间Ｘ 射线散射理论分析（ＦＲＳ ＸＲＳＡ）与ＳＡＸＳ研究了ＨＥＰＰ在应变（ε）与回复（Ｒ）过程中结晶、取向与超结构的变化．结果指出，ε可以诱发结晶，但当ε≥３０％后，结晶度（ＸＷＣ）趋于不变：ε可以导致晶粒破碎；ε与Ｒ对取向分布与平均取向基本上无影响，这符合片晶平行分离模型，而非叶簧弯曲模型；发现，在ε≤３０％时，层状片晶的分离为主要过程，而当ε＞３０％后，则分离的片晶会发生断层滑移；ε可以诱发微孔，类似地当ε＞２０％，微孔尺寸亦趋不变．从凝聚态结构阐明了ＨＥＰＰ在ε Ｒ过程中不同阶段的结构变化     

聚（β－羟基丁酸酯）／聚双酚A羟基醚共混体系相容性及结构的研究

ＤＳＣ和ＦＴＩＲ测试表明，结晶／非晶共混体系聚（β－羟基丁酸酯）（ＰＨＢ）／聚双酚Ａ羟基醚（ＰＢＨＥ）是部分相容的．熔融结晶退火可以大大提高共混物的结晶度，增加其相容性，７５／２５组分ＰＨＢ相结晶度最大，５０／５０组分（０２０）、（１３０）晶面微晶尺寸最大．ＳＡＸＳ研究表明，纯ＰＨＢ的中间层约为１．５ｎｍ，片层厚约４．０ｎｍ；共混物的中间层在２．０ｎｍ左右，片层厚在５．０—７．２ｎｍ之间，５０／５０组分片层最厚．７５／２５组分晶相和非晶相的密度差最大．     

LLDPE／EAA共混体系结晶行为及相容性

通过ＤＭＡ、ＤＳＣ、偏光显微镜（ＰＬＭ）、ＷＡＸＤ及力学性能测试等方法，对线性低密度聚乙烯（ＬＬＤＰＥ）／乙烯－丙烯酸共聚物（ＥＡＡ）共混体系的研究表明，ＬＬＤＰＥ与ＥＡＡ的非晶相可部分相容，结晶相不能形成共晶；共混物结晶时，两组分相互影响，ＬＬＤＰＥ的结晶速度高于ＥＡＡ，两者结晶没有进入对方晶胞中．还发现ＬＬＤＰＥ与ＥＡＡ力学性能上相容．低含量ＥＡＡ共混体系显示出较佳的力学性能．     

LLDPE／LDPE共混体系的相容性与性能

ＬＬＤＰＥ／ＬＤＰＥ共混体系的相容性与性能杨毓华，花荣，白春霞，于旻李三喜，葛铁军（中国科学院长春应用化学研究所长春１３００２２）（沈阳化工学院高分子系沈阳）关键词ＤＳＣ，ＷＡＸＤ，力学性能，ＬＬＤＰＥ，ＬＤＰＥ，共混，相容性非晶－非晶－结晶共混体系...     

聚环氧乙烯／聚乙基恶唑啉共混体系结晶行为及相容性的研究

用偏光显微镜ＤＳＣ，ＩＲ和ＷＡＸＤ等测试方法对聚环氧乙烷／聚乙基恶唑啉共混体系结晶行为及相容性进行了研究。结果表明，ＰＥＯ含量在３０％以上的共混体系中，几乎完全被球晶充满，非晶态ＰＥＯＸ作为微区分散在大球晶之间或之中；含量为２０％的共混体系照片上呈树枝状晶；含量低于１０％时则看不到结晶出现，体系形成单一的非晶相。     

辐照异相成核结晶PA1010体系的ESR研究：结晶表面积对俘陷自由基…

本文通过ＷＡＸＤ，ＤＳＣ方法讨论成核剂对ＰＡ１０１０的聚集态结构的影响。用ＥＳＲ研究辐照不同态结构ＰＡ１０１０体系的俘陷自由基行为。结果表明：俘陷自由基－ＣＨ２ＣＯＮＨＣＨＣＨ２－主要存在于结晶表面，结晶的表面积越大，俘陷自由基－ＣＨ２ＣＯＮＨＣＨＣ２－的含量越高，在一定条件下，如升温，常温放置一段时间，转化为俘陷自由基－ＣＨ２Ｃ＝０的量也越大；俘陷自由基－ＣＨ２Ｃ＝０主要存在于非晶区。     

结晶聚合物的辐照效应——Ⅰ.尼龙-1010的聚集态结构对其辐射化学反应的影响

本文用DSC,WAXD,ESR和介电谱以及凝胶分数测定等技术,研究Nylon-1010的聚集态对γ-辐射化学反应以及辐照后热处理结果的影响。结果表明,辐照Nylon-1010的交联与裂解反应主要发生在非晶区或结晶表面,进一步证明了非晶区也是辐射后交联和后裂解主要反应区。     

Temperature effects on radiation induced phenomena in polytetrafluoroetylene (PTFE)-Change of G-value

Temperature dependencies on the radiation induced phenomena and G-value of polytetrafluoroethylene (PTFE) have been studied in a temperature range 77–653 K. It is well known that main chain scission occurs very effectively below the melting temperature of PTFE (600 K). We have found in our experiments that G-value of chain scission increases significantly with increasing irradiation temperature, until 600 K. In addition to that, we have realized that crosslinking occurs by irradiation in the molten state at 613 K (Tabata, 1992; Oshima et al., 1995; Tabata et al., 1996). In the molten state, G-value of crosslinking was found to be 0.35 (number of crosslinking/100 eV absorption), as a lower limit, and the apparent G-value of chain scission is drastically reduced. Above 633 K, radiation induced crosslinking mainly occurs, however parallel thermal depolymerization or decomposition takes place to some extent.     

结晶聚合物的辐射效应 Ⅰ.γ-辐照尼龙1010的聚集态结构

本文通过WAXD和DSC等方法研究了γ-辐照尼龙1010聚集态结构的变化,结晶损伤和无定形化的过程。这些过程和结晶与非晶界面原子参与化学反应密切相关,结晶损伤从结晶表面开始,随着辐照剂量增加逐渐向结晶内伸展,直到完全无定形化。     

Molecular weight changes induced in an anionic polydimethylsiloxane by gamma irradiation in vacuum

An anionic almost monodisperse linear polydimethylsiloxane (PDMS) was subjected to gamma irradiation under vacuum at room temperature. The molecular weight changes induced by the radiation process have been investigated using size exclusion chromatography (SEC) with refraction index (RI) and multi angle laser light scattering (MALLS) detectors, to obtain the number and weight average molecular weights of the irradiated samples.The analysis of the data indicates that crosslinking reactions predominated over scission reactions. The results obtained by an SEC-RI have confirmed the presence of small, but measurable amounts of scission.A previously developed mathematical model of the irradiation process that accounts for simultaneous scission and crosslinking and allows for both H- and Y-crosslinks, fitted well the measured molecular weight data. This prediction is in accordance with the experimental data obtained by ²⁹Si-Nuclear Magnetic Resonance spectroscopy (NMR) and previously reported data for commercial linear PDMS (Satti et al., 2008).     

Mimicking the biomolecular control of calcium oxalate monohydrate crystal growth: effect of contiguous glutamic acids

Scanning confocal interference microscopy (SCIM) and molecular dynamics (MD) simulations were used to investigate the adsorption of the synthetic polypeptide poly(l-glutamic acid) (poly-glu) to calcium oxalate monohydrate (COM) crystals and its effect on COM formation. At low concentrations (1 μg/mL), poly-glu inhibits growth most effectively in ?001? directions, indicating strong interactions of the polypeptide with {121} crystal faces. Growth in ?010? directions was inhibited only marginally by 1 μg/mL poly-glu, while growth in ?100? directions did not appear to be affected. This suggests that, at low concentrations, poly-glu inhibits lattice-ion addition to the faces of COM in the order {121} > {010} ≥ {100}. At high concentrations (6 μg/mL), poly-glu resulted in the formation of dumbbell-shaped crystals featuring concave troughs on the {100} faces. The effects on crystal growth indicate that, at high concentrations, poly-glu interacts with the faces of COM in the order {100} > {121} > {010}. This mirrors MD simulations, which predicted that poly-glu will adsorb to a {100} terrace plane (most calcium-rich) in preference to a {121} (oblique) riser plane but will adsorb to {121} riser plane in preference to an {010} terrace plane (least calcium-rich). The effects of different poly-glu concentration on COM growth (1-6 μg/mL) may be due to variations between the faces in terms of growth mechanism and/or (nano)roughness, which can affect surface energy. In addition, 1 μg/mL might not be adequate to reach the critical concentration for poly-glu to significantly pin step movement on {100} and {010} faces. Understanding the mechanisms involved in these processes is essential for the development of agents to reduce recurrence of kidney stone disease.     

聚甲基丙烯酸甲酯辐射裂解和消旋的空间立构效应

本文研究了三种不同空间立构聚甲基丙烯酸甲酯的辐射效应,提出裂解过程是一种裂解与重合的动态平衡过程。分子量降低和消旋作用对温度的依赖性,是由于分子运动和笼罩效应以及重合的空间位阻效应所致。辐照温度愈高,裂解产额愈大。相同条件下辐照,全同立构比无规立构试样的裂解产额更大。 全同立构聚甲基丙烯酸甲酯辐照后,不仅分子链断裂,而且空间立构也发生很大变化。随着辐照剂量的增加,全同立构含量逐渐减少,而无规立构含量和间同立构含量却逐渐增加。     

Effect of gamma radiation on chlorobutyl rubber vulcanized by three different crosslinking systems

The development of halogenated butyl rubber (chlorobutyl) in the 1950s and 1960s greatly extended the usefulness of butyl. Their properties allowed the development of more durable tubeless tires with the air retaining innerliner, chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl. When polymers are subjected to high energy radiation, a number of chemical reactions may occur following the initial ionization and excitation events. These reactions lead to changes in the molecular weight of the polymer through scission (S) and crosslinking (X) of the molecules and affect the physical and mechanical properties. In the halobutyl rubbers the chain scission may predominate. This work aims to show effects of gamma radiation in properties of chlorobutyl rubbers vulcanized with sulfur, sulfur donor and phenolic resin. The butyl rubber has been already studied by us previously. The samples were characterized before and after irradiation. Gamma radiation doses used were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy, in order to identify which cure system is the most stable under irradiation. In this study we observed that the properties of all samples were affected irrespective of the vulcanization system.     

Effect of the phenolic antioxidants on the structure of gamma-irradiated model polyethylene

High energy radiation has been successfully employed to modify the chemical structure of commercial polymers. It induces at least two types of reaction in polyethylene: crosslinking and chain scission. In addition the efficiency of the radio-induced reactions can be affected by the presence of antioxidants. The purpose of this work is to study the effect of the irradiation on a model polyethylene containing a phenolic type antioxidant. Samples containing 0.1% and 1% by weight of Irganox 1010 (Ciba-Geigy) were irradiated under vacuum at room temperature with different doses of gamma rays from a ⁶⁰Co source. Changes in structure and the average molecular weight were followed by gel permeation chromatography and low angle laser light scattering. The critical doses for gelation were determined as a function of the antioxidant concentration. Theoretical calculations to predict the evolution of molecular structure with extent of radiation were performed using a probability model. The agreement between the calculated and the measured molecular weights is very good.     

Modelling molecular weight changes induced in polydimethylsiloxane by gamma and electron beam irradiation

A commercial linear polydimethylsiloxane (PDMS) was subject to gamma irradiation under vacuum and in air, as well as to accelerated electron beam radiolysis (EB). All irradiation treatments were done at room temperature. The molecular weight changes induced by the radiation processes have been investigated using size exclusion chromatography (SEC) with refraction index (RI) and multi angle laser light scattering (MALLS) detectors to obtain the number and weight average molecular weights of the irradiated samples.

The analysis of the data indicates that crosslinking reactions predominated over scission reactions in all cases. Gamma irradiation under vacuum was the most efficient process within the analyzed dose range, reaching the gel point earlier. Irradiation in the presence of oxygen induces oxidative effects, both in gamma and EB irradiations. A previously developed mathematical model of the irradiation process that accounts for simultaneous scission and crosslinking and allows for both H and Y crosslinks fitted well the measured molecular weight data.     

Structure characterization of native cellulose during dehydration and rehydration

The goal of this study is to investigate the hydration and dehydration induced structural changes of native cellulose. Never dried cotton, and never dried bacterial cellulose with and without added matrix polymer xyloglucan, are examined under the influence of dehydration and rehydration. Significant crystal structure changes were observed in the later stage of drying for both cotton and bacterial cellulose (BC). The 1 % lateral expansion in glucan chain spacing and 17 % decrease of calculated Scherrer dimension were detected for cotton due to the distortion of the structure possibly caused by mechanical stresses associated with drying. No detectable changes on average glucan chain spacings were observed for large BC crystals. However, an average width decrease by 4.4 nm was discovered in the (010) direction, which was more significant than that observed in the (100) and (110) directions. It is hypothesized that co-crystallized elementary fibrils preferentially disassociate along the (010) plane resulting in a significant reduction of crystal width. In the BC-xyloglucan model composite, the presence of xyloglucan does not interfere with the dehydration behavior. Rehydration leads to some structural changes but to a lesser extent than the initial drying. High temperature dehydration induced deformation and crystal size changes are found to be non-reversible due to the removal of the last hydration layer on the cellulose surface.