Appliance Design - August 2007 - (Page 34)

PLASTICS Graph 1. 3M brand glass microspheres product portfolio. Fig. 1. Particle size distribution, density, and hydrostatic strength of 3M’s extrusion-grade microspheres. in Table 1 and Figure 1. The grades were selected to illuminate processing, handling and property differences. They ranged from high strength bubbles currently used in plastic applications (3M™ S60HS Glass Bubbles), to the new product which is higher in strength (3M™ Performance Additives iM30K). Not only is the iM30K optimized for compressive strength, but it has a noticeably smaller particle size and narrower particle size distribution compared with S60HS. Stronger, smaller microspheres will be able to withstand more stringent processing conditions such as higher rpm screws, higher shear rate mixers, etc. These new bubbles also show improved mechanical properties of the final composite properties. Extrusion of the iM30K product is more straightforward than for S60HS. Though sidefeeding (side-stuffing) of the iM30K product downstream is still desirable, experiments adding the microspheres with resin pellets in the extruder hopper or top-feeding them near the hopper have shown these approaches to be potentially viable. Many processors and compounders are not equipped to do side-stuffing or able to change screw designs. A microsphere that is robust to various processes, such as iM30K additives, can provide an economical solution for many applications. Table 2 shows examples of formulations and typical physical properties achieved in a commercial grade of Nylon 66 (Zytel®6 101LNC010) compounded with S60HS, iM30K, and S80HP glass microspheres. A Leistritz ZSE-40 twin-screw extruder was used for compounding the glass microspheres into Nylon 66. The glass microspheres were added downstream using a side stuffer. A general-purpose injection-molding machine (BOY 50M) with a three-zone screw (feed, compression and metering) was used to injection mold ASTM test specimens for physical property measurements. Physical property testing was done in accordance with the following ASTM methodologies: 4Flexular strength and modulus: ASTM D790. 4Notched izod impact: ASTM D252 4Tensile properties: ASTM D638. 4Elongation at break and yield: ASTM D638. Data in Table 2 show that the part density decreases from 1.14g/cc for regular Nylon 66 to 1.03g/cc at a 20 percent volume loading of iM30K additives and 0.98g/cc at a 30 percent volume loading of iM30K additives. This corresponds to a density reduction of ~10 percent and 14 percent respectively over standard Nylon 66. The formulation containing S60HS shows significant density reductions over Nylon 66. All the glass microspheres formula- tions also provide a significant increase in tensile and flex modulus as well as flex strength as compared to Nylon 66. Although there is a slight decrease in tensile strength with glass microsphere loading levels, this property reduction can be minimized by using the high-strength, small 3M microsphere iM30K. The biggest drawback of adding hollow glass microspheres to Nylon 66 is reduced notched Izod impact strength of the composite. This is not unexpected as glass microspheres are essentially non-reinforcing fillers dispersed into a plastic material. However, as can be seen in Table 1, over a 50 percent improvement in the Izod impact strength was realized in this experiment by using iM30K microspheres in the formulations instead of S60HS. This is most likely due to the smaller size of these microspheres compared to S60HS. Another experiment was conducted with a molded 3M™ Filtrete™ Cabin Air Filter (CAF) frame consisting of a standard 20 weight percent talc-filled homopolymer — black, Piolen® PPTV20A157. This has been compared to a 20 weight percent 3M Performance Additives iM30K-filled PP homopolymer — black, Piolen® PPGB20A15. The talc has been replaced with the 3M Performance Additives iM30K and was compounded by the company PIO Kunststoffe Table 2. Mechanical properties of hollow glass microspheres in nylon 66. 34 applianceDESIGN August 2007 www.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - August 2007

Contents Editorial Shipments/Forecasts News Watch A Reed Switch is Simople, yet Versatile, and Designers are Finding New Uses for this Time-Tested Technology A Novel Actuation and Sensing Technology can Register a Light Touch, but Resist Blows from a Hammer Tracing the Source of Noise is Made Easier with Noise Source Identification Methods Appliance Noise can be Annoying, but Designers have Many Material Choices to Help Rein in the Racket Nanocomposites are No Longer a Technology for the Future. These Plastic Materials are Already on the Job A New High-Strength, Low-Density Glass-Microsphere Additive can Improve Plastic Part and Molding Performance A New Electromagnetic Weld/Bonding Process Helps Ensure Long-Term Integrity of Joints in Plastic Parts Snap-Based Technology Eases Installation and Makes Products More Serviceable Two-Part Silicone Adhesives Provide a Rapid-Cure Alternative to Traditional One-Part Silicones Classified DesignMart Advertiser’s Index Association Report: GAMA

Appliance Design - August 2007

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