橡实淀粉多晶体系结晶度测定

运用广角X-射线衍射分析方法对橡实淀粉的结晶结构进行了系统研究,结果表明:橡实淀粉粒是一种由非晶相、亚微晶相和微晶相三种结构所组成的多晶体系,其结晶度分别为锥栗淀粉34.88%、茅栗淀粉35.12%、小红拷淀粉35.23%、栓皮栎淀粉35.31%、硬斗石栋淀粉33.53%、星毛石砾淀粉34.69%、美叶石栋淀粉35.06%、长叶石烁淀粉31.58%、云山青冈淀粉33.83%、大叶青冈淀粉32.11%。

EH-型催化剂异相聚合聚乙烯结晶性能研究 Ⅰ.稀溶液结晶

用小角X-射线散射、广角X-射线衍射、差示扫描量热法,研究了EH-型钛系催化剂异相聚合聚乙烯稀溶液结晶的熔点、熔化热、结晶度、长周期、晶区厚度和非晶区厚度随分子量与结晶温度的关系,并着重讨论了不同温度下稀溶液结晶聚乙烯的晶体完整性。

Preparation and Structure of Poly(ethylene-co-vinylacetate)/Montmorillonite Nanocomposites

Poly(ethylene-co-vinylacetate)/sodium montmorillonite(EVA/MMT)and Poly(ethylene-co-vinylacetate)/organophilic montmorillonite(EVA/o-MMT)nanocomposite were prepared by solid-state mixing.The morphology and structure of the composites were explored by scanning electron microscopy(SEM),wide-angle X-ray diffraction(WAXD),differential scanning calorimetry(DSC),and dynamic mechanical analysis(DMA).The results showed that the intercalated nanocomposite was successfully synthesized for EVA/o-MMT system,while in the EVA/MMT nanocomposite,MMT were poorly dispersed in the order of μm.An unexpected rubbery plateau modulus of EVA/o-MMT nanocomposite above melting point of EVA was explored by DMA.The possible origins of this high-temperature modulus were analyzed.

WAXD and FTIR Studies of Electron Beam Irradiated Biodegradable Polymers

Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer crosslinking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation ofPLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50：50 （w：w） blend were electron beam irradiated using electron beam accelerator Dynamitron （E = 1.5 MeV） from Radiation Dynamics, Inc. at doses in the range of 50 kGy to 103 kGy in order to evaluate the effect of electron beam radiation. Wide-angle X-ray diffraction （WAXD） patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and Fourier transform infrared spectroscopy （FTIR） spectra was obtained using a NICOLET 4700, attenuated total reflectance （ATR） technique. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was verified broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index （CI） decreased with radiation dose above 500 kGy. But then, PLLA CI increased with radiation dose above 750 kGy. From another point of view, PLLA presence on the 50：50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 103 kGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.

Physio-and chemo-dual crosslinking toward thermoand photo-response of azobenzene-containing liquid crystalline polyester

Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series of azobenzenebased thermotropic liquid crystalline polyesters were synthesized by introducing mesogenic dial named 4,4＇-bis（6-hydroxyhexyloxy）azobenzene（BHHAB）, 2-phenylsuccinic acid（PSA）, and different contents of 1,2,3-propanetricarboxylic acid（PTA） as the chemical crosslinker. All these polyesters showed good thermal stability and smectic liquid crystalline phase. Wide-angel X-ray diffraction（WAXD） and the fluorescence emission spectra confirmed the existence of π–πstacking interactions as the physical crosslinking in the polymer chains, particularly at the lower content of PTA. However, when the PTA content increased, the chemical crosslinking changed the chain conformation, and thus the intensity of physical crosslinking slackened gradually. Combining the physical and chemical crosslinking, these polyesters showed the thermoplastic processability, thermal shape memory, heat-assisted healing and photoresponsive behaviors. Taking advantages of these features, these multiple stimuli–responsive polymers can bring more chances for smart materials such as soft actuator.

Mechanical and thermal properties of mesogen-jacketed liquid crystalline polymer/epoxy resin composites

The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis(TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction(WAXD) and scanning electron microscope(SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.

Shape-stabilized phase change materials with high phase change enthalpy based on synthetic comb-like poly(acrylonitrile-co-ethylene glycol)for thermal management

Shape-stabilized poly（acrylonitrile-co-ethylene glycol） （PANEG） copolymer with comb-like structure was prepared via simple free-radical solution polymerization, where acrylic acid poly（ethylene glycol） methyl ether ester （MPEGA） and acrylonitrile （AN） were employed as monomers. Fourier transform infrared spectroscopy （FTIR）, 1H and 13C nuclear magnetic resonance spectroscopy （1H and 13C NMR）, wide-angle X-ray diffraction （WXAD） were used to characterize the chemical structure of resultant PANEG. In addition, the influences of MPEGA contents on energy storage performance, thermal reliability and thermal stability of PANEG materials were evaluated based on differential scanning calorimetry （DSC）, polarizing optical microscopy （POM）, thermal infrared imager and thermogravimetry analyzer （TG）. The comb-like PANEG demonstrated a favorable temperature regulation performance and thermal reliability. With the increase of MPEGA contents, the enthalpy of PANEG increased, and when the content of MPEGA was 80 wt%, the phase change enthalpy of synthesized PANEG-80 reached to 106.70 J/g with a stable heat storage performance after 100 thermal cycling. Thermal infrared images and cooling curves revealed that synthetic PANEG could sustain a temperature in ranges of 22-31 ℃ for continuous 25 min, presenting excellent temperature regulation performance. Also, comb-like PANEG could be uniformly dissolved in dimethyl sulfoxide （DMSO）, indicating that PANEG phase change fibers with potential applications in fields of intelligent thermoregulating textile and heat energy management could be obtained via one-step wet spinning.

The thermodynamic properties of flow-induced precursor of polyethylene

Flow-induced preordering or precursor(FIP) has been studied in a series of lightly cross-linked high-density polyethylene with a combination of extensional rheology and in situ synchrotron radiation small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) measurements. Based on the incipient strains of SAXS and WAXD signals during extension in a large temperature range, strain-temperature diagrams for flow-induced preordering and nucleation were constructed and revealed that flow-induced crystallization(FIC) undergoes two stages: melt-precursor transition(MPT) and precursor-nuclei transition(PNT). At different temperatures, FIP with different inner structures and morphologies can be induced by strain; these embryos have shape and structure that are related to those of the corresponding critical nuclei. With the strain-temperature diagrams, the thermodynamic properties of FIP are deduced, which shows that compared with the relative nuclei the FIP always has a lower bulk free energy(?H) and a much lower surface free energy(?e). In extreme cases(high temperature), the ?e of FIP can be negligible. The quantitative estimation of the thermodynamic parameters suggests the existence of variant FIPs, which plays a vital role for the subsequent progress of PNT and the whole process of FIC.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.