Zum Mischen rheologisch inhomogener Stoffsysteme auf Einschneckenmaschinen

Zusammenfassung Das Mischen von Stoffen mit unterschiedlichen rheologischen Eigenschaften in Schneckenmaschinen ist in der Kunststoffauf- und -verarbeitung eine Standardaufgabe. Trotzdem gibt es hierfür kein zufriedenstellendes mathematisch-physikalisches Modell. Daher werden zunächst einfache Mischmodelle diskutiert. Auf der Basis dieser Modelle wird dann unter Berücksichtigung der Besonderheiten des Plastifizierextruderprozesses eine Mischgütebeziehung mathematisch formuliert. Die experimentelle Überprüfung erfolgt mit Hilfe der Grauwertanalyse extrudierter Zweistoffsysteme, bei denen ein Stoff mit Ruß eingefärbt war. Da der Mischprozeß hochgradig stochastisch ist, streuen die Meßergebnisse. Unter Berücksichtigung dieses Tatbestandes ist der theoretische Ansatz zufriedenstellend.

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Mixing of polymer resins with different rheological properties is a usual demand in plastics processing using screw extruders. A mathematical model describing this processing problem sufficiently is not known, however. Therefore, simple mixing models will be discussed. Based on these, a concept for the calculation of mixing homogeneity will be presented, including the particular requirement of the plasticating screw process. An experimental investigation utilizes the grey-value analysis of extruded two-component materials, which in one phase is carbon-black filled. Considering the fact that the mixing process is highly random, the theoretical model leads to a good level of aggreement with the scattering measurement data.

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b Schneckenkanalbreite - B Bandbreite der Grauwerte - c Konstante - mittlere Konzentration, bezogen auf die Grauwertbandbreite - h Höhe, Gangtiefe, Schneckenkanalhöhe - h ₀ Gangtiefe der Einzugszone - h ₁ Gangtiefe der Ausstoßzone - L Länge - gemittelte Schmelzebettlänge - n Exponent des Potenzfließgesetzes - s Standardabweichung der Grauwerte bezogen auf die Grauwertbandbreite - S Standardabweichung der Grauwerte - t Verweilzeit - t ₁ kürzeste Verweilzeit - mittlere Verweilzeit - ₀ Umfangsgeschwindigkeit - mittlere Geschwindigkeit - V Volumenstrom - w Dicke eines Kontrollelements - w Ausstreichdicke eines Kontrollelements - x Koordinate - Mittelwert der Grauwerte - y Koordinate - Scherdeformationswinkel - Scherdeformation - mittlere Scherdeformation - Schergeschwindigkeit - Viskosität - ₁ dimensionslose kürzeste Verweilzeit - dimensionsloser Volumenstrom - _LSM laminarer Schermischgrad - _{LSM, the} theoretischer laminarer Schermischgrad - _{LSM, exp} experimenteller laminarer Schermischgrad - ² Varianz der Verweilzeit im Schmelzebett - Schubspannung - Gangsteigungswinkel der Schnecke - ø Volumenanteil - dimensionslose Kennzahl     

The Mechanical Properties,Compatibility, and Thermal Stabilities of POE-Graft-Methyl Methacrylate and Acrylonitrile(POE-g-MAN)/ Styrene-Acrylonitrile Copolymer (SAN Resin) Blends

POE-graft-methyl methacrylate and acrylonitrile (POE-g-MAN) was prepared by graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto polyethylene-octene copolymers (POE) with suspension polymerization. POE-g-MAN/SAN resin blends (AOMS) were prepared by blending POE-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The mechanical properties, compatibility, and thermal stabilities of AOMS were studied. The notched impact strength of the blends reached 54.0 kJ/m² when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN, benzoyl peroxide dosage, and POE content in AOMS were 15 wt%, 1.0 wt%, and 25 wt%, respectively. Transmission electron microscopy analysis showed that the highest toughness occurred when the size of POE-g-MAN particles and the surface-to-surface inter-particle distance were proper. Scanning electron microscopy analysis indicated that the AOMS fracture surface had plastic flow visible, which looked like a fibril morphology when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN was 15 wt%. The toughening mechanism of AOMS was shear yielding of the matrix, which endowed AOMS with remarkable toughness. Dynamic mechanical thermal analysis showed that the compatibility of the POE phase and SAN phase improved after graft copolymerization of MMA and AN onto POE. When the grafting chain polarity was appropriate, the miscibility between POE-g-MAN and SAN resin was the best. Thermogravimetry analysis showed that thermal stability of AOMS increased with increasing AN units in POE-g-MAN.     

Performance and Mechanism of Epoxy Resin for Reinforcement of Styrene–Butadiene Rubber

Styrene–butadiene rubber (SBR) vulcanizates reinforced by epoxy resin (EP) have been synthesized by an in-situ vulcanization and curing process. The influences of synthetic parameters, such as the contents of EP, carbon black, and types of compatilizers, on the microstructures, vulcanization, and mechanical properties of SBR have been investigated. It was found that EP in SBR exists in the form of a fibrillar interpenetrating network, which is important for the enhancement of mechanical properties of SBR. The experimental results showed that when the percentage of EP was in the range of 10–20%, the composite materials had the best comprehensive performance. In comparison with pure SBR, the tear strength and the tensile stress at 300% elongation of SBR-EP composite were increased significantly. The method can be applicable for other rubber vulcanizates to improve their mechanical properties.     

Reactive Compatibilization of Poly(Butylene Terephthalate)/Acrylonitrile-Styrene-Acrylate Blends by Epoxy Resin: Morphology and Mechanical Properties

The effect on the notched Izod impact strength of poly(butylene terephthalate) (PBT) by blending it with acrylonitrile-styrene-acrylate (ASA) was examined. Epoxy resin (ER) was demonstrated to be an efficient compatibilizer for the partially compatible blends of PBT/ASA. It requires only a very small amount of ER to improve the toughness of the PBT/ASA blends drastically. Furthermore, there exists an optimum proportion of ER added to achieve maximum notched Izod impact strength. Transmission electron microscopy (TEM) observation suggests that the ER in the PBT/ASA/ER blends suppressing the tendency of coalescence of ASA, leading to better dispersion of the ASA particles. Field emission scanning electron microscopy (FESEM) shows that ER enhances the phase dispersion and the interfacial adhesion between the PBT and ASA phases, it improves the compatibility between PBT and ASA. The compositions in the interphase was continuous, which results in multiphase composites with a graded interphase. It is suggested that enhanced interphase adhesion was necessary to obtain improved dispersion, fine phase morphology, and better toughness.     

羧甲基交联壳聚糖树脂的合成、表征及其应用

羧甲基交联壳聚糖树脂(C-C-CTS)与普通壳聚糖树脂相比,既能在酸性介质中不溶又不失去其螯合性能.其合成采用简单的2步法,首先用还氧氯丙烷交联,然后羧甲基化.C-C-CTS的结构用红外光谱和X-ray光电子能谱进行表征.C-C-CTS树脂对重金属离子有很好的螯合吸附能力,每种树脂对Pb(Ⅱ),Cu(Ⅱ)和Zn(Ⅱ)的吸附能力分别为8.73,10.12和4.89 mg·g-1,并且在不同的pH条件下对Pb(Ⅱ)、Cu(Ⅱ)和Zn(Ⅱ)有很好的选择性吸附,最后还讨论了C-C-CTS树脂对Pb(Ⅱ)的吸附机理.     

天然水中微量稀土元素镧的流动注射在线预浓集ICP光谱法测定

本文采用P507萃淋树脂为固定相,应用流动注射(FI)在线预浓集技术,建立了镧的ICP发射光谱分析方法,对天然水中的微量镧进行了测定,获得满意结果。     

塑料复制光栅研究

本文介绍塑料溶液流延技术复制光栅,用于灯具、电扇、舞台等,成本廉价、工艺简便、适于批量生产,为全息光栅在民用领域中推广具有广泛应用价值。     

石盐中硼含量及其同位素的准确测定

基于Cs₂BO+₂的正热电离质谱法测定样品中硼同位素时,硼含量的准确测定直接制约着硼同位素测定的成败。目前,使用电感耦合等离子体原子发射光谱仪(ICP-OES)测定高盐样品的硼含量仍然存在很大问题,主要体现在两个方面： 高盐的基体干扰和仪器检出限制约,而仅仅依靠简单的稀释无法很好的解决这些困难。因此对样品进行硼元素的预富集以及基体离子的去除是十分必要的。在使用硼特效树脂进行硼元素的吸附时发现部分钠离子也会被同时吸附,故采用3 mol·L-1的氨水可以洗脱大部分吸附的钠离子而不造成硼的损失,达到了去除基体的目的。随后使用10 mL 75 ℃的0.1 mol·L-1盐酸将硼特效树脂吸附的硼洗脱实现了样品中硼的富集。ICP-OES测定硼含量时,选择波长为208.900 nm,样品的加标回收率在106.00%～108.40%之间,检出限为0.006 mg·L-1,定量下限为0.02 mg·L-1。通过不同盐度下的12次重复实验,其相对标准偏差小于5%,在1.94%～3.37%之间,因此该方法是可行的,并不存在偶然误差。联合此方法和Cs₂BO+₂离子的正热电离质谱法,成功测定了8个地质石盐样品的硼含量及硼同位素组成。     

脂松香、石炭酸松香树脂和马林酸松香树脂的红外光谱剖析及鉴别

本文对脂松香、石炭酸松香树脂和马林酸松香树脂的红外光谱剖析及鉴别，方法快速，简便，准确。     

离子交换富集-导数火焰原子吸收法测定自来水中Cu,Fe和Zn

本文研究了用 2 0 1× 7阳离子交换树脂对自来水中的微量元素进行交换富集 ,采用微量脉冲进样 导数火焰原子吸收法测定富集后溶液中的Cu ,Fe和Zn ,该方法灵敏度分别为 0 2 9,0 5 9和 0 0 6 μg·L- 1 ,精密度分别为 4 2 8% ,1 95 %和 2 2 8% ,检测限分别为 1 2 8,5 85和 0 6 8μg·L- 1 ,回收率分别为 91 13% ,10 1 34%和99 84 % ,本方法大大减少了需样量 ,简便快速 ,灵敏度高。