Evaluation of the Activation Energy for Pyrolytic Degradation of Poly-L-Lactide (PLA) During Artificially Accelerated Aging.

In the course of this study, the pyrolytic degradation characteristics of three poly(lactic acid) (PLA) types were investigated under inert conditions using dynamic thermogravimetric analysis (TGA) across the temperature range of 23°C-600°C with four heating rates. Specifically, the activation energy and its implications were determined at different stages of degradation. For this purpose, a comparative analysis of various isoconversional methods, including Kissinger, Flynn-Wall-Ozawa (FWO), Friedman, and Kissinger-Akahira-Sunnose (KAS) was undertaken to evaluate the reliability of each.

Correlations between the Aging Behavior and Finite Element Method Simulation of Three Silicone Elastomers.

The material parameters required to describe material behavior can change with the age of the components due to chemical and physical aging processes. The finite element method (FEM) is a tool for designing components for later use. The aim of this study is to correlate the change in the mechanical properties of silicone elastomers from standard tests over a longer period of time with the parameters of the Mooney-Rivlin model.

Differentiation between Hydrolytic and Thermo-Oxidative Degradation of Poly(lactic acid) and Poly(lactic acid)/Starch Composites in Warm and Humid Environments.

For the application of poly(lactic acid) (PLA) and PLA/starch composites in technical components such as toys, it is essential to know their degradation behavior under relevant application conditions in a hydrothermal environment. For this purpose, composites made from PLA and native potato starch were produced using twin-screw extruders and then processed into test specimens, which were then subjected to various one-week ageing processes with varying temperatures (23, 50, 70, 90 °C) and humidity levels (10, 50, 75, 90%). This was followed by mechanical characterization (tensile test) and identification of degradation using Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance spectroscopy (NMR).

Analysis of the Similarity between Injection Molding Simulation and Experiment.

In the plastics industry, CFD simulation has been used for many years to support mold design. However, using simulation as a substitute for experimentation remains a major challenge to this day. This is due to the unknown congruence between simulation and experiment.

High Consistency Silicone Rubber Foams.

Silicone elastomers are high-performance plastics. In the extrusion process, only high-consistency silicone rubbers were used. In order to reduce the cost and weight, silicone rubbers can be foamed during processing.

UVC Irradiation as a Surface Treatment of Polycarbonate to Generate Adhesion to Liquid Silicone Rubber in an Overmolding Process.

This study investigates the adhesion properties of polycarbonate (PC) and liquid silicone rubbers (LSR) through surface activation using ultraviolet C (UVC) radiation. While self-adhesive LSRs adhere easily to certain thermoplastic composites such as polybutylene terephthalate (PBT) and polyamides (PAs), bonding to PC typically requires surface treatment due to the lack of compatible functional groups. Previous methods like plasma or flame treatment have been effective, but the use of UVC radiation for surface activation remains unexplored.

Correlation between the activation energy of PLA respectively PLA/starch composites and mechanical properties with regard to differ accelerated aging conditions.

Within this research semi-crystalline polylactide and composites with 50 wt.% native potato starch were compounded and injection molded. The material was mechanically characterized by tensile, three-point bending, and Charpy impact tests.

Analysis of the Machine-Specific Behavior of Injection Molding Machines.

The performance of an injection molding machine (IMM) influences the process and the quality of the parts manufactured. Despite increasing data collection capabilities, their machine-specific behavior has not been extensively studied. To close corresponding research gaps, the machine-specific behavior of two hydraulic IMMs of different sizes and one electric IMM were compared with each other as part of the investigations.

MC-Injection Molding with Liquid Silicone Rubber (LSR) and Acrylonitrile Butadiene Styrene (ABS) for Medical Technology.

The multicomponent injection molding of liquid silicone rubbers (LSR) with thermoplastics, such as polybutylene terephthalate (PBT) or polyamide (PA), is a state-of-the-art technique and is used in the manufacturing process for many components in the automotive industry and in the field of sanitary engineering. Standard thermoplastics, such as acrylonitrile butadiene styrene (ABS), cannot be bonded with silicone rubbers in injection molding because of their low heat deflection temperature. In this study, we investigated ABS grades approved for medical applications to show how dynamic mold heating and various pretreatment methods for thermoplastic surfaces can be used to produce ABS-LSR test specimens.

Influence of Ethylene Oxide and Gamma Irradiation Sterilization Processes on the Properties of Poly-L-Lactic-Acid (PLLA) Materials.

In order to encourage the substitution of petrochemical polymers in medical technology with sustainable, bio-based materials, there is an urgent need for further investigations, especially data regarding their sterility performance. Within the scope of the investigations, selected material properties of poly-L-lactic-acid (PLLA), a specific type of poly(lactic-acid) (PLA), were analyzed before and after sterilization (using ethylene oxide or gamma irradiation) in order to investigate deviations in its chemical structure, wettability, optical, and mechanical properties. In particular, parameters such as molecular weight, complex viscosity, tensile strength, water contact angle, and color were discussed.

Emission and Mechanical Properties of Glass and Cellulose Fiber Reinforced Bio-Polyamide Composites.

Climate change, access, and monopolies to raw material sources as well as politically motivated trade barriers are among the factors responsible for a shortage of raw materials. In the plastics industry, resource conservation can be achieved by substituting commercially available petrochemical-based plastics with components made from renewable raw materials. Innovation potentials are often not used due to a lack of information on the use of bio-based materials, efficient processing methods, and product technologies or because the costs for new developments are too high.

The Influence of Thermal and Mechanical Stress on the Electrical Conductivity of ITO-Coated Polycarbonate Films.

The influence of thermomechanical stress on the conductivity of indium tin oxide (ITO)-coated polycarbonate (PC) films was investigated. PC is the industry's standard material for window panes. ITO coatings on polyethylene terephthalate (PET) films are the main commercially available option; as such, most investigations refer to this combination.

Analysis and Validation of Varied Simulation Parameters in the Context of Thermoplastic Foams and Special Injection Molding Processes.

The simulation solutions of different plastic injection molding processes are as multifaceted as the field of injection molding itself. In this study, the simulation of a special injection molding process, which generates partially foamed integral components, was parameterized and performed. This partial and physical foaming is realized by a defined volume expansion of the mold cavity.

Flexible Electrochromic Device on Polycarbonate Substrate with PEDOT:PSS and Color-Neutral TiO as Ion Storage Layer.

Electrochromic (EC) windows on glass for thermal and glare protection in buildings, often referred to as smart (dimmable) windows, are commercially available, along with rearview mirrors or windows in aircraft cabins. Plastic-based applications, such as ski goggles, visors and car windows, that require lightweight, three-dimensional (3D) geometry and high-throughput manufacturing are still under development. To produce such EC devices (ECDs), a flexible EC film could be integrated into a back injection molding process, where the films are processed into compact 3D geometries in a single automized step at a low processing time.

Influence of Different Hot Runner-Systems in the Injection Molding Process on the Structural and Mechanical Properties of Regenerated Cellulose Fiber Reinforced Polypropylene.

The increasing demand for renewable raw materials and lightweight composites leads to an increasing request for natural fiber composites (NFC) in series production. In order to be able to use NFC competitively, they must also be processable with hot runner systems in injection molding series production. For this reason, the influences of two hot runner systems on the structural and mechanical properties of Polypropylene with 20 wt.

Modification of Polyamide 66 for a Media-Tight Hybrid Composite with Aluminum.

Metal-plastic composites are becoming increasingly important in lightweight construction. As a combination, e.g.

Influence of Accelerated Aging on the Fiber-Matrix Adhesion of Regenerated Cellulose Fiber-Reinforced Bio-Polyamide.

With regard to the sustainability and biological origin of plastic components, regenerated cellulose fiber (RCF)-reinforced polymers are expected to replace other composites in the future. For use under severe conditions, for example, as a housing in the engine compartment, the resistance of the composites and the impact on the fiber and fiber-matrix adhesion must be investigated. Composites of bio-polyamide with a reinforcement of 20 wt.

Influence of Chitosan and Grape Seed Extract on Thermal and Mechanical Properties of PLA Blends.

Blends based on polylactic acid (PLA), chitosan, and grape seed extract (GE) were prepared by extrusion and injection molding. The effect of chitosan (5% and 15% on PLA basis) and natural extract (1% on PLA basis) incorporated into the PLA host matrix was explored regarding the thermal and mechanical properties. GE showed antioxidant activity, as determined by the DPPH assay method.

Weathering of a Polyurethane-Based Gel Electrolyte.

A recently described flexible polyurethane electrolyte was artificially weathered at 25/50 °C and 50% r.h. in air and at 25 °C in a dry nitrogen atmosphere, each with and without UV irradiation.

Online Prediction of Molded Part Quality in the Injection Molding Process Using High-Resolution Time Series.

Process-data-supported process monitoring in injection molding plays an important role in compensating for disturbances in the process. Until now, scalar process data from machine controls have been used to predict part quality. In this paper, we investigated the feasibility of incorporating time series of sensor measurements directly as features for machine learning models, as a suitable method of improving the online prediction of part quality.

Influence of Fiber Volume in Hybrid Short Glass/Cellulose Reinforced Thermoplastic Compounds.

Glass fibers (GF) and regenerated cellulose fibers (RCF) are possible partners in the hybrid reinforcement of thermoplastics because of their different properties. Due to the weak bonding properties of polypropylene, coupling agents are used and the fiber volume content is set high to achieve high reinforcing effects. A lower fiber content of GF can raise the toughness properties of a reinforced polypropylene which is investigated in this study with different ratios of GF and RCF.

Influence of Processing Glass-Fiber Filled Plastics on Different Twin-Screw Extruders and Varying Screw Designs on Fiber Length and Particle Distribution.

Due to their valuable properties (low weight, and good thermal and mechanical properties), glass fiber reinforced thermoplastics are becoming increasingly important. Fiber-reinforced thermoplastics are mainly manufactured by injection molding and extrusion, whereby the extrusion compounding process is primarily used to produce fiber-filled granulates. Reproducible production of high-quality components requires a granulate in which the fiber length is even and high.

Determination of Local Electrical Properties Using a Potential Field Measurement for Electrically Conductive Carbon Fiber Reinforced Plastics with Metal Contact Pins Joined via Injection Molding.

Carbon fiber reinforced plastics (CFRP) bear a high potential in terms of electrical conductivity and its potential applications. A locally resolved electrical measurement method for these anisotropic materials is a key prerequisite for understanding the structural and manufacturing process-related interrelationships. The aim of this paper is to develop a measurement method that allows this to be achieved and also to investigate areas of overmolded metal contact pins in detail.

Polyurethane-Based Gel Electrolyte for Application in Flexible Electrochromic Devices.

For the application in flexible electrochromic devices (ECDs) on plastic substrates, a new polyurethane-based gel electrolyte was manufactured. In this context, the curing behavior and the influence of the proportion of solvent and salt on the ion conductivity as well as the optical and mechanical properties were investigated. Furthermore, the stoichiometric ratio of the polyurethane matrix was varied to influence the ion conductivity.

Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres.

To reduce the material costs as well as the density of Liquid Silicone Rubber (LSR), LSR foams can be produced in an injection molding process. Expandable thermoplastic microspheres can be used as blowing agents. This publication deals with the analysis of the cell structure of these LSR foams.