X射线衍射法测定聚丙烯树脂结晶度及影响因素探讨

采用X射线衍射法测定了聚丙烯树脂的结晶度,考察了制样方法、测试条件以及计算方法等因素对测试结果的影响.通过精密度试验考察了方法的精密度.结果表明,95％置信水平时,在重复性试验条件下,两次测定结果绝对差不大于3.5％;在再现性试验条件下,两次测定结果绝对差不大于5.0％.方法具有较好的重复性和再现性,可以满足聚丙烯树脂...     

DSC法测定聚乙烯结晶度的研究

研究了用DSC法测定聚乙烯（PE）结晶度的理论和新方法，通过X射线衍射（WAXD）及常规DSC法对测得的不同PE的结晶度进行了对比，探讨了DSC技术对测定高聚物结晶度的合理性，通过调制式DSC（MDSC）对PE热容的研究，证明了在低温下存在着小晶片的熔融，进而能显著影响所测定的PE的结晶度，最后提出了由于PE结晶度的大小与环境温度密切相关，故用DSC技术测定其结晶度时，选择基线的温度范围具有重要意义。     

利用X射线衍射计算机分峰法测定CPE的结晶度

本文利用日本Rigaku3015X射线衍射仪、Apple(Ⅱ)微型计算机对低氯含量的CPE(氯化聚乙烯)的结晶度进行了测定,并将此结果与Mathews法分析结果进行了比较。实验结果表明:X射线衍射计算机分峰法所得结果更为合理。     

PUET的WAXD计算机分峰及结晶度计算

本工作采用日本理学电机GreigerflexD/max-rA型旋转阳极超强力X-射线衍射仪进行宽角X-射线衍射(WAXD)实验,2θ为0-39°,CuKα工作电流30mA,电压30kV。样品为聚醚型聚氨醋(PUET)。     

W型铁氧体衍射叠合峰分峰拟合软件应用探讨

本文以溶胶凝胶-自蔓延法在不同温度下制备的W型铁氧体XRD衍射曲线为数据来源,选取其中有谷点、有肩点和完全重合3种类型的衍射叠合峰,分别采用Jade、Peakfit和Origin软件,对3类叠合峰进行分峰拟合,并从拟合准确性、绘图能力、专业性、适用范围、操作简易程度对3种软件的分峰拟合功能进行了对比分析。结果表明：origin软件不适用于完全重合叠合峰的分峰拟合,而Jade和Peakfit软件均可实现3类叠合峰的分峰拟合;origin在绘图和操作简易程度方面体现一定优势;Peakfit在适用范围及拟合准确性方面较具优势;而Jade在专业性、拟合准确性、适用范围方面能力均较为突出。     

X射线衍射法测定聚氟乙烯树脂结晶度

一、前言测定聚合物结晶度的方法有密度法,红外吸收法,核磁共振法,熔融热法,吸附法,X射线衍射法。前面几种方法,不是手续繁杂,条件苛刻,干扰因素多,不易重复,就是需要标样。X射线衍射法,物理上的意义是测定聚合物的有序性,它只要求在衍射图中把结晶部分的衍射与无定形部分的衍射清晰地分     

密度天平法测定聚乙烯树脂密度方法的探讨

通过试验考察了密度天平法测试聚乙烯树脂密度的重复性和准确性, 同时对比了密度梯度法测定聚乙烯密度的结果,两种方法测试结果能满足现密度方法要求的准确度和精密度范围,重复测定两结果之差：高密聚乙烯树脂≤0.0005 g/cm3,低密聚乙烯树脂≤0.0003 g/cm3。两种方法可以互替,相互补充,并讨论了影响密度天平法测定因素。     

密度梯度柱法测定聚乙烯树脂密度

采用密度梯度柱法测定聚乙烯树脂的密度,研究影响该方法测定聚乙烯树脂密度准确性的因素.实验结果表明:样品的处理方式、密度梯度柱的使用温度、密度梯度柱的配制效果等因素均可对测试结果造成影响.针对这些影响因素,提出了相应措施,并确定了适用于测定密度范围(0.9530±0.0030)g·cm-3高密度聚乙烯树脂密度梯度柱的配制...     

热处理对高密度聚乙烯结晶度及力学性能的影响

为了考察热处理对高密度聚乙烯(HDPE)结晶度及力学性能的影响,分别在温度为70和100℃下对HDPE样品进行30,60和90min热处理,并对样品进行DSC测试和拉伸和冲击力学性能测试,实验结果揭示了:HDPE样品的结晶度随着热处理温度的提高和时间的延长均呈上升趋势,但100℃下热处理60min结晶度的提高基本趋于稳定;热处理温度的上升和时间的延长会降低HDPE样品的冲击强度,断裂伸长率和屈服应变,会提高其拉伸强度和断裂强度。     

Molecular probe studies of crystallinity in polyethylene

The molecular probe technique uses a standard gas chromatograph modified to obtain a printed digital record of retention time vs. column temperature to be obtained automatically. From this the observed specific retention time, V_g, can be calculated. If V_g is the theoretical value it can be deduced that: % Crystallinity = [1 ? V_g/V_g′ ] × 100. Experimental results using Tenite 800 and Tenite 3310 polyethylene produced and sold by Eastman Chemical Products Inc., Kingsport, Tennessee, U.S.A. justify this equation.     

Determination of matrix crystallinity of composites by X-ray diffraction

Determination of the degree of crystallinity of the matrix of polymer matrix composites by wide-angle X-ray diffraction is discussed. An extensive theoretical review is given, and many of the practical difficulties are also discussed. Poly(aryl ether ether ketone)-carbon fiber composites are used as example materials. It is shown that although wide-angle X-ray diffraction is potentially useful for unoriented samples, there are practical and theoretical difficulties in applying the technique to highly oriented materials.     

Determination of crystallinity of an aliphatic polyester by FTIR spectroscopy

Summary In this work, FTIR spectroscopy was applied to the determination of crystalline content in an aliphatic polyester. To this goal, a range of wavelengths (from 560 cm^-1 to 680 cm^-1), non conventional for this kind of polymers, was selected by analyzing spectra collected during isothermal crystallization tests. A deconvolution of the IR spectrum in that range showed the presence of three peaks sensitive to the amorphous content and one sensitive to the crystal content. An analysis of the time evolution of the absorbances allowed to determine the parameters needed to determine the absolute crystallinity degree. The time evolution of crystallinity during isothermal tests at different temperatures was successfully compared with results obtained by DSC. The procedure was also favorably compared with the result obtained by WAXD on a solid sample at room temperature.     

氯化聚乙烯残余结晶度的测定

试验研究氯化聚乙烯（CPE）残余结晶度的测定.结果表明,用差示扫描量热（DSC）法直接对CPE样品进行残余结晶度测定,灵敏度较低,通用型CPE残余结晶度测定结果偏低;采用溶剩物-DSC法测定,可大幅提高检测灵敏度和准确性.     

On-line density and crystallinity of polyethylene terephthalate during melt spinning

The density and crystallinity of polyester fiber were measured on the moving threadline during the melt spinning process. The density was calculated by applying the continuity equation at points along the length of the threadline. Experimental inputs to the equation included paralle, on-line measurements of fiber diameter, fiber velocity, polymer mass flowrate, fiber temperature, and fiber birefringence. When spinning speeds exceeded 4500 m/min, a distinct rise in density occurred along the threadline. This rise corresponded with the rise in birefringence.     

Radiation-induced crystallinity changes in linear polyethylene: Influence of aging

A previous paper described an unusual crystallinity effect observed in ultrahigh molecular weight linear polyethylene (UHMW PE) and conventional high density polyethylene (HDPE). It was discovered that upon exposure to high energy radiation, these polymers experience a significant increase in the degree of crystallinity. The present paper describes another equally unexpected and surprising phenomenon observed in irradiated UHMW PE and HDPE. It was accidentally found that the irradiated polyethylenes exhibit an aging effect; their heat of fusion and hence their degree of crystallinity increases monotonically with the aging time (since initial irradiation) at ambient conditions. Surprisingly, the aging process in irradiated polyethylenes was observed to persist even after 31 months. The magnitude of the aging effect is a strong function of the initial molecular weight of the unirradiated polymers and the irradiation dose. The aging phenomenon could not be accelerated by thermal annealing. The exact mechanisms causing the aging phenomenon remain rather elusive at the present time, but possible reasons are explored.     

X-Ray photoemission study of plasma modified polyethylene surfaces

X-Ray photoelectron spectroscopy (XPS) was used to determine plasma induced chemical species on the surface of polyethylene (PE). Argon plasmas were found to have no detectable chemical effect on the PE surface, whereas oxygen and nitrogen plasmas created new chemical species which altered the chemical reactivity of the PE surface. Oxygen plasmas were found to react more rapidly with the PE surface than nitrogen plasmas. The degree of incorporation of new chemical species in the near surface region is approximately 20 at. % at the saturation level for both oxygen and nitrogen plasmas. Core level spectra for oxygen and nitrogen plasma treated PE suggest the formation of primarily C-O-C species in the former and C-N species in the latter. Angle-resolved XPS measurements indicate that the depth of incorporation of new chemical species is confined to the top 25 A.     

Study of the change of crystallinity of polyethylene on oxidation by inverse phase gas chromatography

Inverse-phase gas chromatography has been used for monitoring the oxidative degradation of low density polyethylene, which has great industrial importance. Polyethylene was oxidized in a gas chromatographic column at 145°C with an oxygen flow of 10 mL/min for different periods. After oxidation for a specified period, the crystallinity and solvent interaction parameters were monitored. For crystallinity studies, the solvent probe was n-decane, and for solvent interaction these were n-decane, o-xylene, n-butanol, and n-butyl acetate. With oxidation there was a gradual fall in crystallinity, and after 15 h the crystallinity was practically nil. Total loss of crystallinity also occurred at 175°C with 1 h passage of oxygen. This has also been confirmed by differential scanning calorimetry. The specific retention volumes of polar solvents showed a sharp increase with oxidation. The results, which are different from that reported in the literature, have been explained.     

超高相对分子质量聚乙烯特性黏数的测试方法

采用毛细管黏度计法测定超高相对分子质量聚乙烯(UHMWPE)的特性黏数([η]),对[η]的准确测定的影响因素进行了探讨。结果表明:以十氢萘为溶剂,使用前进行蒸馏提纯;在配制UHMWPE溶液时,加入质量分数为0.2%的抗氧剂1010,按预溶胀、溶胀、溶解3步骤进行溶解,溶解温度150℃,溶解时间0.5 h,配制UHMWPE溶液浓度为100~600 mg/L;严格控制温度(135±0.2)℃,所测UHMWPE的[η]平行性较好,相对标准偏差为1.08%。     

水热法合成β沸石结晶度的研究

以四乙基氢氧化铵为模板剂 ,采用水热法合成 β沸石。考察水热法合成 β沸石时体系中有机模板剂用量、水硅比、钠硅比及晶化时间等对合成的 β沸石相对结晶度的作用。样品的相对结晶度用X射线衍射仪分析。得出各种因素对合成 β沸石相对结晶度的影响