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991.
中部烟叶配伍性评价与分析 总被引:1,自引:0,他引:1
对河南省不同地区13种中部烤烟两两间的配伍性进行了评价、分析。结果表明,相同地区烟叶间的总体配伍性优于不同地区间的烟叶,各单项指标配伍性的变化规律与总体配伍性不完全相同。烟叶间的配伍性与其感官质量得分差、水溶性总糖含量差和均值以及混配比例有关,水溶性总糖含量差小于7%或均值在25%~30%范围内的烟叶配伍性好,根据感官质量得分差和水溶性总糖含量差可以预测烟叶间的配伍性。水溶性总糖含量差小于7%且感官质量得分差小于3分的烟叶可等比例混配,反之,则应增加感官质量较好烟叶的使用比例。 相似文献
992.
993.
To improve the processability of ethylene‐α‐olefin copolymers (POE), POE and POE/polystyrene (PS) blends were extruded in the presence of ultrasound. On the one hand, the effect of ultrasound on the die pressure drop, extrudate productivity, melt viscosity of POE, and the processing behaviors of POE and POE/PS (80/20) blend were studied. The results showed that with increasing ultrasound power, the die pressure and melt‐apparent viscosity of POE decreased whereas the productivity of POE extrudates increased, then the processability of POE was greatly improved. On the other hand, the effects of ultrasound on the morphology, rheological, and mechanical properties of POE/PS (80/20) blend were studied. Capillary rheological results showed that the merger of ultrasound and the addition of PS showed a synergistic improvement of processability of POE. From morphological observation and rheological analysis, the compatibility of the blend was also improved in the presence of 200W ultrasound. As a result, the stress at break of compatibilized POE/PS (80/20) blend increased from 9.2 to 11.0 MPa, and the dynamic storage modulus increased at experimental temperature range, indicating that the mechanical properties of POE/PS blends can be improved by ultrasound‐assisted extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
994.
The effect of short‐chain amide (AM) molecules on the intercalation of montmorillonite clay has been investigated by the melt blending of polypropylene (PP) with clay in the presence of AM molecules such as 13‐cis‐docosenamide (erucamide). Polypropylene–clay nanocomposites (PPCNs) were prepared by the co‐intercalation of maleic anhydride grafted polypropylene (PP–MA) and an AM compound. The resulting nanocomposite structures were characterized with X‐ray diffraction (XRD) and transmission electron microscopy, whereas the thermal characterization of the PPCNs was conducted by thermogravimetric analysis. XRD results showed that the AM molecules intercalated into clay galleries and increased the interlayer spacing, a result confirmed by surface energy (contact angle) and melt flow index measurements. This additive allowed the formation of an intercalated nanocomposite structure, but an exfoliated PPCN structure was also formed with the use of AM with a PP–MA‐based compatibilizer. A new preparation method for PPCNs was, therefore, developed by the co‐intercalation of AM and PP–MA; this resulted in a significantly improved degree of intercalation and dispersion. The enhanced thermal stability of PPCN, relative to pure PP, further demonstrated the improved clay dispersion in the nanocomposite structures prepared by this method. A possible mechanism for the co‐intercalation of AM and PP–MA into the clay galleries is proposed, based on hydrogen bonding between these additives and the silicate layers. Consideration is also given to possible chemical reactions and physical interactions in this rather complex system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
995.
We successfully synthesized monomer casting polyamide 6 (MCPA6)/poly(methyl methacrylate) (PMMA) blends in two steps: (1) radical polymerization of methyl methacrylate in ?‐caprolactam and (2) anionic ring‐opening polymerization of this ?‐caprolactam solution. The influence of PMMA on the crystallization behavior of MCPA6 was studied with differential scanning calorimetry and X‐ray diffraction, which showed that PMMA could act as a heterogeneous nucleation agent and favored the formation of the γ‐crystalline form. The rheological properties were also studied and indicated that PMMA reduced the interaction between MCPA6 chains by lowering the density of hydrogen bonding. This study used a novel and convenient method to prepare microporous MCPA6/PMMA particles that involved removing the continuous phase. Their surface area and thermal stability were characterized by the Brunauer–Emmett–Teller method and thermogravimetric analysis, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
996.
In this investigation, poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) blends (w/w) were prepared in a Brabender (South Hackensack, NJ) plasticorder with a thermoplastic mixing chamber (type W60) preheated at 180°C. These blends were further converted into films by a conventional solution casting method and characterized with Fourier transform infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction, mechanical property measurements, impact strength testing, ultraviolet–visible spectroscopy, refractive‐index measurements, and contact‐angle study. The Fourier transform infrared results indicated that the compatibility between these two systems resulted from hydrogen bonding between the carbonyl group of PMMA and the CH2 group of PVDF. The thermal analysis showed depressions in the glass‐transition temperature, melting temperature, and crystallization temperature. The heat of crystallization increased with an increase in the PVDF content in the blend. An increase in the heat of crystallization meant an increase in the crystallinity. An increase in the cooling rate increased the crystallization rate. The improvement in the mechanical properties of the blend films indicated that the observed behavior was ascribable to a more coherent structure of the blends due to strong specific interactions between PMMA and PVDF chains. The impact strength analysis revealed a substantial increase in the impact strength from 21.64 to 38.52 J/m. Optical absorption spectra suggested the presence of an optical band gap energy that increased with an increase in the PVDF content in the blend. The contact angle against water increased with the PVDF content in the blend film, and this was caused by the hydrophobicity of PVDF due to the CF2 group of PVDF. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
997.
998.
聚甲醛合金的增容改性研究进展 总被引:1,自引:0,他引:1
介绍了不同增容剂增容聚甲醛(POM)/热塑性聚氨酯、POM/丁腈橡胶、POM/凝胶丁腈共聚物、POM/(乙烯/辛烯)共聚物、POM/(乙烯/丙烯/二烯)共聚物、POM/(甲基丙烯酸酯/丁二烯/苯乙烯)共聚物、POM/聚丙烯、POM/高密度聚乙烯合金体系的研究进展,并对其增容效果做了比较。 相似文献
999.
聚醚型聚氨酯弹性体的合成及其动态力学行为 总被引:3,自引:1,他引:2
采用两步合成法,以4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,相对分子质量分别为1000、2000、4000的聚氧化丙烯二元醇(PPG)为软段,制备了一系列聚醚型聚氨酯(PUR)弹性体,研究了预聚体异氰酸酯指数R及软段相对分子质量对PUR动态力学性能的影响。结果表明,预聚体R值增大,即PUR的硬段含量增加,储能模量G′提高,软段相的玻璃化转变温度(Tg)升高,软硬相区的相容性增大;软段相对分子质量增加,PUR的G′下降,软段相的Tg降低,并出现硬段相的玻璃化转变,软硬相区的相分离程度增大。 相似文献
1000.