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The comparative thermal and chemical study was done on five mediterranean plants: Acacia dealbata, Quercus coccifera, Rosmarinus
officinalis, Thymus vulgaris, Ulex parviflorus. Results were independent of the drying way of samples (110°C, 60°C or lyophilisation).
The correlation between the maximum decomposition rate at about 300°C and the content of cellulose was confirmed. The samples
cut on the same foot of Ulex parviflorus, in spring, produced, for the thorns and sprigs, a minimum in cellulose content,
and a maximum in lignine content. The results were inverse in winter.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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In this work, we describe and evaluate the use of the Fourier transform infra red (FTIR) spectroscopy in DRIFT mode (diffuse
reflectance infra red Fourier transform) in an environmental device to follow the functional evolution of cellulose during
thermal treatments. The potentialities (and difficulties) of the technic are given.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Difluorodioxophosphates may be used as ceramic phosphate precursor, and their thermal behaviours are very important. In this paper we study by TG and DTA the thermal stability for iron(II) salt. In argon atmosphere, we obtain in a first time the melting of salt at 240°C then the classical breaking up into solid orthophosphate and POF3 exhaust. If the sample of iron(II) difluorodioxophosphate is heating in air, we do not obtain the melting phenomena, but at the same temperature an exothermic phenomenon that conducts to the formation of iron(III). We observe a mass increase. By IR analysis, we can show that this oxidation is obtained without change of difluorodioxophosphate structure. 相似文献
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L. El Watik P. Antonetti Y. Claire H. Zineddine J. Kaloustian C. Rossi A. Perichaud 《Journal of Thermal Analysis and Calorimetry》1998,53(1):297-308
The authors studied the ignifugation and the kinetic of thermal degradation of the Styrene-Butadiene copolymer with an intumescent
system Ammonium polyphosphate-Pentaerythrinol-Melamine. For that, they used the thermogravimetric and oxygen index techniques.
The best formulation of intumescent system which can give the optimum results is proposed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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研究了两种马来酸酐接枝聚丙烯(PP-g-MAH)在不同含量时对聚丙烯(PP)/滑石粉复合材料的力学性能、雾化性能和线性膨胀系数的影响.结果表明,接枝物的加入能提高复合材料的拉伸性能、冲击性能和弯曲性能,但随着含量的增加拉伸强度、冲击强度和弯曲强度及弯曲模量有所降低.在含量相同时,接枝物1对冷凝组份的影响更小.复合材料的线性膨胀系数随接枝物含量的增加先减小后增加. 相似文献
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聚丙烯鱼眼与晶点的成因 总被引:1,自引:1,他引:0
聚乙烯 (PE)、聚氯乙烯 (PVC)、聚苯乙烯(PS)、聚丙烯 (PP)等高分子材料在加工成型为薄膜时 ,常会出现气泡或小粒子 ,因气泡形状与鱼眼(Fisheyes)相似 ,故得名 .有关鱼眼的成因 ,都认为与挤出混合不均一或与高分子融体的污染有关 [1~ 4 ] ,也有人从 GPC的数据推测与聚丙烯的低分子成份有关 [5] ,但未用具体样品进行研究 .本文的鱼眼是指 PP在制作编织袋过程中出现的小气泡 ,此气泡随薄膜吹塑比增大而增大 ,在拉伸方向呈现中部最薄的鱼眼 ,是吹塑过程中的爆破点 .使 PP编织丝的强度达不到应有的要求而影响质量 .本文的晶点是指在膜上… 相似文献
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Denis Lorenzi Gabriella Sartori Giuseppe Ferrara Luca Fambri 《Macromolecular Symposia》2011,301(1):73-81
Summary: Spinnability of isotactic polypropylene iPP (melt flow 25 g/10 min) was studied after addition of three nanofillers at 0.3% by wt., two nanoclays and a modified hydrotalcite. TGA evidenced the increase of thermooxidation stability in nanofilled iPPs. All these iPP were successfully processed and tensile properties similar to those of iPP fibers were achieved. Processing and mechanical draw ratio were evaluated. Moreover, nanofilled iPP fibers appeared to be more prone to further drawing, as derived from both the maximum attainable strength and the maximum attainable drawing, as presented in the interpretation model of mechanical testing. 相似文献
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聚丙烯釜内合金具有良好的刚韧平衡性能,历经30多年的发展,在包装、汽车和建筑等领域已得到广泛的应用。其优异的性能及复杂的多相、多组分结构更是引起了相关领域研究者的高度关注。聚丙烯釜内合金是一种在聚合釜内直接合成的多相、多组分聚合物体系,其初始产品常以粉末或球型颗粒的状态存在,具有非常复杂的相形态,并且在加工成型过程中,由于相形态的演变会形成更加丰富的微结构,从而对聚丙烯釜内合金最终的力学性能产生决定性的影响。目前对于聚丙烯釜内合金体系的分子链结构-聚集态结构-产品性能之间的构效关系仍然有很多问题亟待解决。近期研究表明在某些情况下,聚丙烯釜内合金体系中增韧相形成“核-壳”型结构(或多重“核-壳”型结构)时,可以实现最佳的刚性与韧性的平衡,但对于这些“核-壳”结构形成条件的控制及结构成分的精确测定仍有不足。本文主要总结了近年来聚丙烯釜内合金相态研究的进展,展望了该领域可能的发展方向。 相似文献
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Various thio-organotin compounds have been reacted with t-butyl hydroperoxide in order to determine whether this oxidation can be responsible for the stabilizing capacity of some thio-organotins towards polyolefin degradation. The kinetics of t-butyl hydroperoxide disappearance, in the presence of thiotin compounds, shows different reactivity according to the structure of oranometallic reagent. Product analysis indicates organotin oxide, dialkyl disulfide and t-butanol as major reaction products. The reactivity sequence towards hydroperoxide is the same as the order observed for polypropylene stabilization. 相似文献
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YanXiaCAO MiaoDU QiangZHENG 《中国化学快报》2004,15(5):567-570
The study on rheological properties of a series of mica-filled polypropylene (PP) composites was carried out. The influence of surface-treatment of mica particles on dynamic rheological behavior of the composites were dealt with. The viscosity (η) and dynamic modulus ( G‘ ) of the composite melts were higher than those of PP matrix, especially those for systems treated with silane, which was attributed to the interfacial adhesion enhancement. However, surface-treatment of mica by titanate resulted in lower η and G‘, as compared with the treatment by silane. The reason for this is believed to be the formation of the mono-molecular layer on the mica surface. 相似文献
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交联改性可以提升聚合物材料的机械性能、热稳定性及化学稳定性。 含有蒽基团的高质均分子量等规聚丙烯(iPP)可由配位共聚合反应制得,随后通过双官能的马来酰亚胺试剂与iPP中悬挂蒽基团间的Diels-Alder反应可以成功制备交联的iPP膜材料。 材料的交联度可以通过凝胶重量分析及膜红外分析得出,并由制备过程中交联剂的加入量有效地调控。 通过示差扫描量热仪(DSC)与广角X射线衍射仪(WAXD)表征发现,随交联度增加,交联改性限制了分子链的运动,iPP的结晶度逐渐降低、结晶能力逐渐下降。 对交联材料的动态热机械分析仪(DMA)测试表明,随交联度增加,iPP的损耗模量逐渐降低,材料韧性变差。 交联iPP的Tg逐渐升高,说明材料的耐热性得到提升。 由于交联形成了聚合物链间的交联网络,形成了更多受力点并且限制了聚合物链的自由移动,交联材料的拉伸强度随交联度的升高而增加,而断裂伸长率逐渐下降。 相似文献