Macromolecular Symposia最新文献

Polymer blends can be compatibilized using block and graft copolymers with blocks identical to, miscible with, or adhering to related components of the blend. In our recent paper, we applied relatively simple models based on the work of Leibler and its modifications by Hong, Noolandi, Retsos, and Anastasiadis. This paper does not deal with new modifications of the theory, but deals with the dependence of the calculated decrease in interfacial tension on Flory–Huggins interaction parameter, surface to volume ratio, homopolymers chain lengths, and copolymer compatibilizer blocks lengths, including those not tested in the preceding paper. In dependence on copolymer block length and on Flory–Huggins interaction parameters, the compatibilizer effect reaches maxima. Their dependence on remaining parameters is presented here.

In biogenic base resins with various hardeners, part of the epoxidized linseed oil was replaced with increasing proportions of 5–25% by weight of orange oil, limonene, limonene epoxide, and limonene dioxide. The temperature development while curing, foam formation, and final hardness depended on the oxygen content of the limonene derivative used. Orange oils and limonene slowed the curing process down. The resulting hardness of the biobased epoxies decreased for all samples when adding 0–25% by weight. After six weeks of curing, Shore A 40–70 was achieved compared to Shore A 80–90 of the unmodified systems. Epoxidation of limonene to (+)-limonene-1,2-epoxide increased the reactivity. Here too, the achievable Shore hardness A decreased linearly to 60–85 with increasing addition of limonene epoxide. A replacement of 5% of the epoxidized linseed oil was possible without significant loss of material hardness. With limonene dioxide, the resins heated 75–85% faster than samples without the additive. As the proportion increased, all sample variants foamed, at maximum temperatures of up to 122°C. The suitability as a surface sealant for floor coatings was determined visually and through mechanical tests. Limonene dioxide improved flow and gloss, but the resin systems became more brittle and showed less adhesion to the floor surface. The resins were resistant to UV weathering. Due to the short gelling time, the resins should preferably be processed using the spray process.

A digital model-based correlation between component design, machine programming, and the physically realized component geometry was developed for analysis of critical process parameters in additive manufacturing by Fused Filament Fabrication (FFF). Aiming for a correlation at high throughput rates, a method for specifying the machine control protocol (G-code) was developed, which enables the automated adaptation of wall thicknesses, layer thickness, and support structure geometry. Although this method was applied to planar surfaces in this study, it is suitable for mapping any curved geometry, provided that the cross-section of the printed filament remains unchanged by the printing speed. Thus, a representative pre-manufacturing model is automatically derived from the specific G-code, which is suitable for predicting the structure-property relationships of additively manufactured components. This representative pre-manufacturing model is compared with a second automatically generated post-manufacturing model from physical prints. Thus, the modelled pre-manufacturing structure-property relationships can be compared with the generatively manufactured component structures. Detected deviations between the modelled and manufactured components are suitable for quality management and the optimization of process parameters. In result, a linear statistical model was developed to quantify the relationship between the mechanical component properties and specific G-codes for an FFF component. Additionally, an inverse model was developed to facilitate the selection of process parameters that lead to the desired mechanical properties of components manufactured in FFF.

High-density polyethylene (PE-HD) is being used more and more in critical long-term applications, such as in pipes for the distribution of water and gas. For this reason, it is important to have a strong understanding of those parameters that control the fracture behavior of PE-HD. The main parameters are (i) chain structure, (ii) morphology, and (iii) processing conditions. The structure is characterised by “rapid” SIS/DSC (SIS—Stepwise Isothermal Segregation, DSC—Differential Scanning Calorimetry method). The experimentally measured data were processed using the Avrami equation. Software was developed for the processing, which allows the relevant parameter tau to be determined. This parameter correlates with accelerated fracture mechanics tests.

PP twin-wall sheets offer a durable and lightweight alternative to traditional corrugated cardboard packaging. They offer considerable advantages over cardboard-based solutions, especially in the technical sector, where contamination from oil and high-force applications by metallic components is expected. They can be used, e.g., as separating compartments in transport containers. The toughness of the sheets allows them to reuse the packaging materials multiple times, which makes them more sustainable. The material can also be used as a lightweight and cost-effective structural component, e.g., for case walls. However, the cutting edges resulting from the manufacturing process, usually punching, are critical for the applications mentioned. These are slightly sharp-edged and often open the inner structure of the panels. That can lead to superficial injuries during picking the parts and to dirt accumulation inside the sheets, e.g., from chips. Sealing the relevant cutting edges by means of thermo–mechanical forming offers a reliable solution to the problem. Until now, this has often been limited to straight edges or required extra processes and tools. These tools and processes make the sealing process labor-intensive and time-consuming. With the help of a combination of modern drive technologies, heating technologies, and control technologies, the cut edges of contoured components can also be formed in a single process step. The base for this enhanced process is the engineering of forces, speeds, and thermal conditions. These process parameters are determined in experiments and transferred to suitable models.

The objective of this work is the investigation of reinforcement of elastomers by filler and strain-induced crystallization (SIC) in terms of tensile strength. The model for SIC in elastomers is combined with the model for filler and extended for the simulation of rupture. The morphology generator (MG) enables the generation of various filler dispersions such as fine and coarse. The impact of both the filler volume fraction and the filler dispersion on the tensile strength and the elongation at break of filled model networks are analyzed. In addition, the ultimate mechanical properties of non-strain-crystallizing model networks are compared to that of strain-crystallizing model networks. Moreover, the rupture behavior is investigated by considering snapshots of the model networks. This study shows that the tensile strength is enhanced by SIC with increasing filler loading and by finely dispersed filler. Finally, a modeling methodology is developed, allowing for the study of the general interplay of physical and chemical parameters on rubber reinforcement.