The interfacial tightness of hybrid polymer-metal parts such as injection-molded connectors represents a decisive quality characteristic. Until now, however, there has been a lack of suitable measurement technology with which to quantify the media tightness of such molded parts. A new method delivers significantly more accurate results than previous test methods.

The DDP method enables more accurate determination of the tightness of polymer-metal hybrids

16:9

Measurement Method for the Exact Leakage Determination of Polymer-Metal Hybrid Parts

Messtechnik

Verbundwerkstoffe / Werkstoffverbunde

Kunststoff Werkstoffe

Prüfen von Kunststoffen

Stecker

Elektromechanik

Kunststoff

Bauwesen

Baustoffe

Steckverbinder

How Tightly Sealed are Connectors Really?

Röhm produces antimicrobial PMMA for transparent partitions.

Plexiglas XT Antimicrobial is an extruded sheet material with a special surface treatment on both sides. The coating contains a formulation that controls microbial growth

Polymethylmethacrylat

Thermoplaste

Platten

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Disease Protection by PMMA

Susanne Schröder will become editor-in-chief of the magazines Kunststoffe and Kunststoffe international on December 1, 2020. The current editor-in-chief Dr. Karlhorst Klotz will leave the company by mutual agreement.

Susanne Schröder will become editor-in-chief of the magazines Kunststoffe and Kunststoffe international on December 1, 2020. Until now she has been editor-in-chief of the trade journal FORM+Werkzeug

Werkzeuge für Leichtbauwerkstoffe

Präzisionswerkzeuge

Tiefziehwerkzeug

Dienstleistungen

Werkzeug-, Formen- und Modellbau

Werkzeugüberwachung

Toolmanagement

Werkzeugwechselsysteme, Spritzgieß

Kunststoffverarbeitung: Maschinen und Komponenten

Werkzeuge für die Kunststoffverarbeitung

Spritzgießwerkzeuge

Werkzeug- und Formenbau

Modulare Werkzeugsysteme

Absaugungen für Werkzeugmaschinen

Betriebsausrüstung / Betriebsmittel

Absaugvorrichtungen

Fluorkunststoffe

Werkzeugverwaltungssoftware

Biokunststoffe

Presswerkzeuge, Kunststoff

Werkzeugreinigung, Kunststoffe

Standardkunststoffe

Kunststoffverarbeitung

Lohnfertigung

Technische Kunststoffe

Füllstoffe für Kunststoffe

Kunststoffhandel

Handel

Betriebstechnik für Kunststoffverarbeitung (Peripherie)

Kunststoffverarbeitung: Verfahren

Kunststofffasern

Verstärkungsstoffe

Kunststoff-Recycling

Kunststoff-Aufbereitung

Hochleistungskunststoffe

Qualitätssicherung Kunststoff

Qualitätssicherung

Change in the Chief Editorial Office of Kunststoffe

Aimplas participates in European Space Agency project to develop new materials under microgravity conditions in the Earth’s orbit.

View of the northern region of the Earth.

Unternehmen

kunststoffe.de

Aimplas Supports ESA Project

PMMA for lights, lighting solutions, automotive exteriors, and household appliances will take center-stage on Röhm’s booth at this year’s show.

Displays with a black panel effect for household appliances can be implemented in PMMA.

Messe K-Kunststoffmesse

kunststoffe-international.com

More Design Freedom for Lights

The strong demand for PMMA is based on the continually expanding diversity of applications.

Design trend light: in the TIR lens LFO by Bartenbach and kdg Opticomp made of a Plexiglas PMMA of Röhm, the surface of the lenses is structured using free-form surface facets in such a way that the light appears homogeneous.

Trotz Rohstoffengpässen und Turbulenzen in wichtigen Branchen stehen die  Zeichen für PMMA auf Wachstum

Polymethyl Methacrylate (PMMA): Turbulence in Key Industries

Kennzahlen

Qualitätsmanagement

Despite Raw Material Shortages, the Signs for PMMA Point to Growth

Röhm and OQ Chemicals officially broke ground on a new world-scale methyl methacrylate (MMA) plant.

Röhm, OQ Chemicals and Advent International celebrate groundbreaking ceremony for new 250 ktpa MMA plant at OQ Chemicals’ production site at Bay City.

Röhm and OQ Chemicals Break Ground in Texas

At K 2022, it was clearly shown that with suitable materials not only can CO2 emissions be reduced, but also advantages in component design achieved.

The Japanese chemical company Asahi Kasei showed its concept vehicle at K 2022. The domed roof in particular could lead to a few changes in future automobiles.

With suitable materials CO2 emissions can be reduced and advantages in component design can be achieved.

Automotive Highlights of K 2022

Thermoplastische Elastomere

Silikone

Kunststoffe, biobasiert

Elektromobilität

Mobilität

Streifinger, Florian

Polyamide

Polycarbonat

Suitable Materials for Smart  Vehicle Design

The quality of final products can be increased by using measurement technology for monitoring production processes. Interest in it is increasing especially for compounding. There are various existing methods of non-destructive testing that can also be used inline in the manufacturing process. The different methods are suitable for different applications: an overview of the current capabilities and limitations of the various inline methods.

Fig. 2. Dependence of measurable ultrasonic amplitude (extinction coefficients) of filler content and the accompanying median size of chalk particles in plastics compounds: By using such databank-integrated calibration curves, both of these quality relevant features can be quantified inline by ultrasound

Inline Testing Methods for Monitoring Processes

Mikrowellenmesstechnik

Elektrische / Magnetische Messtechnik

Compoundieren

Transparency in Compounding

The e.GO Life is an affordable electric car for short-range transport. Starting as a development project at the RWTH Aachen University campus, the first cars of this type were delivered in the middle of this year. For this car, the engineers use plastic panels for the vehicle’s body. The large-sized body panels are thermoformed by the plastics-processing company Parat in close collaboration with the plastic sheet manufacturer Senoplast.

All 59 plastic body panels of the e.GO Life electric vehicle were thermoformed very cost-effectively from semi-finished plastic products i. e. coextruded plastic sheets

59 Lightweight Components for the Body of the New Electric City Vehicle e.GO Life

Leichtbau

Flachfolien- und Plattenextrusion

Extrusion

Automotive

Fahrzeugbau

Lightweight Construction

The global market for PMMA continues to benefit from an increasing demand, mainly from the construction and electronics industry as well as the automotive and transportation sector. However, continuing raw material bottlenecks have damped sales, which has also pushed up the price for PMMA.

Lower energy consumption, better plant growth: a company in the Netherlands builds functional greenhouses with the help of lens optics made of a Plexiglas PMMA molding compound

Growth through Diversity for Molding Compounds and Semifinished Products

Polymethyl Methacrylate (PMMA)

Lupine Lighting Systems manufactures extremely bright mountain bike lights with lenses made of Plexiglas. The molding compounds from Röhm meet the most important standards for e-bike and bicycle lighting.

A masterpiece of precision: UPT Optik in Nuremberg produces the lenses for Lupine in an injection molding process using the brand PMMA from Röhm. The material is unsurpassed in its transparency and light guiding properties

Technische Optik

Ingenieurwissenschaften

Optik

Photonik

Bright Lights with Precision Lenses Made from Plexiglas

The transition to electric cars is transforming automotive design. And so polymers producer Röhm has developed special polymethyl methacrylate (PMMA) molding compounds with this in mind. These are sold under the company’s well-known Plexiglas brand. At Fakuma, the company will be demonstrating how they can be used to combine design requirements and functional properties.

Plexiglas Resist AG 100 is used, for example, in Volkswagen’s ID.3 electric vehicle

Elektronik

Messe Fakuma

Greater Design Freedom for Electric Cars

Zumtobel produces moisture-proof luminaires from Plexiglas molding compounds, the polymethyl methacrylate from Röhm.

The Amphibia PM moisture-proof luminaire from Zumtobel is made using the Plexiglas Resist zk5BR special molding compound.

Leuchten / Lichtmanagement

Lichttechnik

High Light Efficiency for a Luminaire

The aim of this joint project is to develop a production cell in which a rear license plate light can be manufactured with hybrid processes without any additional steps such as bonding. Some of the necessary analyses and pre-testing of the material combinations resulting from the structure of the product – plastic housing and optics plus metal conductive tracks – are presented in this article.

Lighting  solutions on various products. 

Manufacture of a Rear License Plate Light in a Highly Integrated Production Cell

Spritzgießen

LED / OLED-Systeme und Faseroptik

Hybrid-Spritzgießen (Metall / Kunststoff)

What Is the Most Suitable  Material Combination?

Characterize Plastic Surfaces More Easily with Atomic Force Microscopy

Atomic force microscopy can be used to determine various properties of polymer surfaces. However, until now it was still necessary to change the hardware on the probe for different measurement methods. A special sensor technology eliminates the need to replace the head. The example of an investigation of a polymer thin film shows how this enables the precise characterization of polymers.

Atomic force microscopy can be used to determine various properties of polymer surfaces. However, until now it was still necessary to change the hardware on the probe for different measurement methods.

Atomic Force Microscopy (AFM) has been used for a long time to characterize mechanical, electrical, magnetic and other surface properties of plastics. When using this microscopy measurement method for characterization, it is often critical that all measurements are performed at the same location on the sample surface. In this case, different surface properties can be correlated accordingly and brought into a quantitative relationship.

Until now, however, AFM measurements with different modes at exactly the same location were difficult to perform, since this usually required a hardware change on the AFM measuring instrument. In this case, the AFM head must be removed and, after appropriate modification, reinstalled. This is not only time-consuming, but also carries the risk of damaging the AFM head. With the AFM-z sensor technology, Anton Paar GmbH has now developed a possibility that allows the use of all available AFM modes in the measuring instrument without hardware change. This allows switching between modes without lifting the AFM head. The characterization of a polymer thin film made from a mixture of polymethyl methacrylate (PMMA) and styrene-butadiene-styrene (SBS) shows how this works in practice.

In Anton Paar’s Tosca series AFM, the z-sensor is integrated in a compact and lightweight “actuator body” without any cables, which ensures safe and easy handling (Fig. 1).

All measurements for the different modes can be performed with only one actuator body. This allows various properties of the sample to be measured reliably and accurately on the nanoscale without hardware modification and associated repositioning of the cantilever. The following modes are available:

<ul><li>Contact Mode,</li><li>Tapping mode,</li><li>Force Distance Curve (FDC),</li><li>Contact Resonance Amplitude Imaging (CRAI),</li><li>Electrostatic Force Microscopy (EFM),</li><li>Magnetic Force Microscopy (MFM),</li><li>Kelvin Probe Force Microscopy (KPFM),</li><li>Conductive AFM (C-AFM).</li></ul>

In the aforementioned characterization, the polymer thin film was measured on a 25 μm x 25 μm area with a resolution of 400 x 400 pixels and a scan rate of 0.5 line/s. The force-distance curves, CRAI measurement, EFM and KPFM were performed at the exact same position. This makes it possible to learn more about the sample within one measurement procedure. Each measurement step determines further qualitative and quantitative sample properties, up to the complete characterization of the sample within the selected AFM resolution.

CRAI Measurement Reveals  Height Differences

First, the mechanical properties of the polymer thin film were investigated using the CRAI mode. This measurement mode is derived from contact mode. This means that the cantilever is in constant contact with the sample in order to record the surface height. At the same time, it oscillates with a certain frequency around its contact resonance frequency. This near-resonance operation exploits the fact that the contact resonance frequency and amplitude depend on the elastic modulus of the sample, so simultaneously recorded amplitude and phase channels reflect the difference in stiffness (Fig. 2).

The height image from the CRAI investigation of the PMMA-SBS blend shows structures or islands within a matrix representing the two different polymers in the blend. The structures are higher than the matrix, as can be seen from the height profile (Fig. 3).

The contrast in amplitude and phase reflects differences in the surface mechanical properties. This reveals the information that the topography image does not show: the higher domains (islands) also include some of the other polymer, so they are not purely one polymer. This observation is a distinct advantage of the CRAI mode, as it enables a more accurate characterization of the nanoscale mechanical properties (Fig. 4).

The FDC measurement was used in the next step to quantitatively determine the elastic modulus of two distinct domains. FDC is a single point measurement of nanomechanical properties. The AFM measures the force between the probe and the sample as a function of the distance the probe moves (Fig. 5).

For quantitative results, a calibration of the cantilever is required (determination of the spring constant, cantilever sensitivity, tip geometry). After the cantilever calibration and the subsequent measurement, using a proper contact mechanics model (Fig. 6), the quantitative information on Young’s modulus, applied force, adhesion force, snap-in force and indentation depth can be easily obtained.

The values determined are similar to the literature values for PMMA or SBS, but do not correspond exactly to these . This is due to the fact that, as seen from the CRAI analysis, the stiffer structures also contain the other, less stiff polymer. It can be concluded that the matrix is predominantly SBS and the structures consist predominantly of PMMA.

Two Pass Technique for the Determination of Contact Potential Difference

In the next measurement section, the electrical properties of the sample were investigated using the KPFM. KPFM measures an electrostatic force field between the tip and the sample and provides quantitative data by measuring the contact potential difference between the tip and the sample. The KPFM is implemented as a so-called two-pass measurement (Fig. 7). In the first pass, the height information is acquired by a tapping mode scan. This is then used as input for the second pass (lift pass). In this case, the cantilever is lifted and the rescans the surface line at a constant height above the sample surface.

The oscillation of the cantilever in the lift pass is not mechanically, but electrically driven, by applying an external AC voltage between tip and sample. The feedback electronics adjust the bias voltage until the oscillation amplitude is nullified. As the result, the contact potential difference between tip and sample, or the surface potential, is obtained. This contact potential difference depends on the difference of the work function between tip and sample. The work function (Φ) is defined as the minimum energy required to remove an electron from a solid and is therefore material specific. Therefore, it can be used to characterize the material composition and relate it to the topography.

Differences in Contact Potential Show Differences in Material Composition

The KPFM results show different electrochemical properties of the matrix and the structures. By correlating the extracted height and KPFM potential profile, it was concluded that the maximum contact potential difference between the matrix and the structures is about 250 mV. Furthermore, a nearly constant and uniform contact potential difference for the matrix is observed. However, this is not the case for the structures. A rather strong variation of the surface potential of the structures can be observed. The question arises whether the difference in contact potential can be unambiguously assigned to the material composition.

To answer the question of the exact polymer distribution and the composition of the structures, a superposition of 3D-CRAI and KPFM measurements is performed. This is only possible if both measurements are performed at exactly the same position. The superposition of the two results provides important additional information. The contact potential difference clearly depends on the composition of the individual structures. The structures where one polymer predominates show the highest potential difference. In contrast, structures consisting evenly of both polymers show a smaller potential difference (Fig. 8).

By analyzing the KPFM results, the quantitative material properties can be determined using the work function. A structure in which a polymer predominates was chosen for the analysis. From the measured maximum contact potential difference, where the composition is dominated by a single polymer, a work function of 4.1 ±0.1 eV was determined for the matrix and 4.3 ±0.1 eV for the structures.

Combination of Measurement Methods Enables Accurate Characterization

The results show that an accurate characterization of different surface properties of polymers is possible by combining the different measurement methods. CRAI and FDC measurements were first used to investigate the mechanical properties of the polymer thin film. Amplitude and phase images of the CRAI mode show important information about locations with differences in mechanical properties i. e. stiffness between the different regions of this polymer blend. FDC measurements provide quantitative information about these differences in the form of the Young’s modulus of elasticity.

KPFM shows different electrochemical properties of the matrix and the structures The analysis of mechanical and electrical properties at exactly the same location on the surface allows the superposition of the CRAI and KPFM results, which provides important insights into the polymer distribution. In addition, the work function allows a quantitative analysis of the material properties.

The investigations illustrate the measurement capabilities of the AFM Tosca series. Due to the AFM technology of z-sensor integration, Tosca series enables a faster and more extensive characterization of the polymer thin film. This allows different material properties to be determined sequentially at exactly the same position using different modes.

Anton Paar GmbH  

https://www.anton-paar.com

Ausgabenartikel

With the Tosca series, all AFM measurements can be carried out with only one actuator body and thus without hardware exchange

Fig. 1. Insertion of the actuator body with cantilever into the AFM: the z-sensor is integrated in the compact and lightweight actuator body without any cables

Fig. 2. Schematic representation of the CRAI measuring principle: differences in the stiffness of the specimen and a height image are generated

Fig. 3. The height image from the CRAI investigation reveals height differences in the polymer thin film. The determined islands are higher than the matrix 

Fig. 4. The CRAI measurement shows a contrast in the amplitude (left) and the phase (right). This indicates that the higher structures consist of not only of one but of both polymers

Fig. 5. Schematic representation of the force-distance curve (FDC): the force between the probe and the sample is measured as a function of the distance the probe moves

Fig. 6. Measurement of the force-distance curve (FDC)

Fig. 7. In the KPFM, the height information is determined by tapping mode scan in the first pass. The second pass (lift) with the cantilever lifted takes place at a constant height above the sample 

Fig. 8. Superposition of 3D CRAI amplitude and contact potential difference (CPD) shows the higher potential difference for structures which are mainly composed of one polymer 

KU 5-21_Anton Paar - Hauptartikel

 Dr. Dr. Jelena Fischer has been working as a product manager for Anton Paar GmbH in Graz, Austria, since 2012.

Dirk Meister has been working as a product specialist for Mechanical Surface Characterization for Anton Paar Germany GmbH since 2019;  <a href="mailto:dirk.meister@anton-paar.com">dirk.meister@anton-paar.com</a>

Michael Schäffler has held various positions at Anton Paar Germany GmbH since 2002, currently as Market Development Manager.

Read the German version of the  article in our magazine Kunststoffe or at  <a href="https://www.kunststoffe.de/a/fachartikel/charakterisierung-ohne-pruefkopfwechsel-322893" target="_blank">www.kunststoffe.de</a>