Imerys Minerals in Polyamide 6
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Imerys Minerals in Polyamide 6 Talc, Mica and Wollastonite IMERYS MINERAL SOLUTIONS Minerals in Polyamide 6 Performance additives are commonly used in the Consistent color coding is used in all graphs for formulation of polyamides and other engineering ease of comparison, with green, blue, red, and black, thermoplastics to provide reinforcement, improve respectively representing GF, talc, wollastonite, and rheology or contribute to other mechanical properties. mica products. The main performance indicators are measured and presented using both ASTM and Chopped glass fiber and mineral additives are among ISO standards, where lighter and darker shades of the most common reinforcing additives used in color, respectively show ASTM and ISO test results. polyamide formulations. The purpose of this technical Differences observed in values of each property bulletin is to compare the effect of glass fiber (GF) and measured by ASTM and ISO tests are due to differences three IMERYS minerals (talc, mica, and wollastonite) in specimen size, rate of measurements and other on rheology, appearance, and mechanical properties of specifics of each test as shown on the graphs. Polyamide 6 (PA6). If different specimen types (e.g. double gated vs. single Additive performance comparison has been conducted gated specimens) or test conditions (e.g. flow vs. cross- at 30 wt% loading for minerals and 20 and 30 wt% flow directions, angle of gloss measurement, etc.) are loading for GF. Two typical wollastonite, mica, and talc compared, dark and light bars are used to differentiate grades are compared in graphical presentation of the the results. results, one representing the highest aspect ratio (HAR) form of each mineral and the other representing the lower aspect ratio (LAR) form. A list of IMERYS products representing each category of minerals featured in this bulletin is provided in Table 1, with the first product listed under each category being the actual mineral shown in the graphical results. RECOMMENDED MINERAL PRODUCTS FOR DIFFERENT CATEGORIES OF MINERALS STUDIED HAR HAR® 3G 84L / HAR® 3G 77L, Talc Products HAR® T84 / HAR® T77, HAR® W92 / HAR® H92 Microcrystalline Crys-talc® 7C Talc Talc HAR Nyglos® 4W-10012, Wollastonite Nyglos® 8-10012 Nyglos® 12-10012, Aspect 4012 / Aspect 3012 M15 Wollastocoat LAR 10 Wollastocoat, Wollastonite 400 Wollastocoat M1250 Wollastocoat Mica M400 Wollastocoat HAR Suzorite 150 PO Mica Suzorite 250-L PO E7542 PO Fine Suzorite 350 PO Mica Suzorite 325-G PO Wollastonite STIFFNESS (FLEXURAL/TENSILE FLEXURAL/TENSILE STRENGTH MODULUS) When it comes to strength performance, GF offers a clear A desired performance of reinforcing additives in advantage over minerals since the performance of minerals Polyamide 6 is their effect on increasing material tested at 30% loading was weaker than that even for 20% stiffness, i.e. flexural or tensile modulus. While glass GF loading. fiber (GF) is the typical standard for reinforcing PA6, 300 our results show that HAR Suzorite mica and HAR talc 257 249 closely match GF performance. The performance of other 250 200 200 200 talc, mica and wollastonite products also falls within the 170 150 performance of 20 and 30 wt% GF filled PA6, with only 150 154 138 137 135 131 124 128 128 137 126 low aspect ratio (LAR) wollastonite being less performing 100 than 20% GF. (MPa) Strength Flexural 50 0 30% GF 20% GF HAR Talc Talc Microcrystalline HAR Wollastonite LAR Wollastonite Mica HAR Suzorite Mica Suzorite Fine 10000 ASTM D790: Light bars – Rate = 1.27 mm/min 9000 ISO 178: Dark bars – Rate = 2.00 mm/min 8467 8291 8000 7648 7887 7504 7484 7331 6921 However, for double-gated specimens with weldline the 6729 7000 6587 6388 6337 performance of wollastonite is approaching that of GF. 5846 6000 5724 5000 Flexural Modulus (MPa) Flexural 4252 3983 4000 160 154 30% GF 20% GF HAR Talc HAR Wollastonite LAR Wollastonite Mica HAR Suzorite Mica Suzorite Fine Microcrystalline Talc Microcrystalline 3000 140 130 ASTM D790: Light bars – Rate = 1.27 mm/min 120 94 ISO 178: Dark bars – Rate = 2.00 mm/min 100 91 86 85 82 82 81 80 78 80 77 60 Above measurements are done on single-gated injection 38 Tensile Strength (MPa) Strength Tensile 40 30 25 molded specimens with no weldline. However, many parts 21 20 made with PA6 compounds do have weldlines due to the 0 30% GF 20% GF HAR Talc Talc Microcrystalline HAR Wollastonite LAR Wollastonite Mica HAR Suzorite Mica Suzorite Fine Single-gated (no Weldline) – Dark bars size and complexity of the parts. Most mould designs Double-gated (with Weldline) – Light bars are also based on the worst case scenario, which is the ASTM D638: Rate = 0.51 mm/min performance results with weldlines. ASTM tensile tests allow for preparing standard Weldines are unavoidable in the production specimens using either a single injection molding gate of many plastic parts. Superior stiffness along that creates no weldline or a double-gated design that with similar strength performance to chopped results in a weldline in the center of the part. Tensile glass fiber make the HAR NYGLOS wollastonite modulus test results for specimens with weldline (light products the reinforcing additives of choice for bars below) show a clear advantage for all mica and talc parts with weldlines. products, plus the HAR wollastonite compared to GF. The tensile modulus without a weldline follows a similar trend to flexural modulus. TENSILE ELONGATION Wollastonite products also show the highest elongation 12000 at break in tensile tests for specimens with or without weldlines. 10000 9211 SEM analyses of the failed specimens show relatively 8564 8548 8477 8269 8032 7903 7863 8000 7672 7379 better alignment or intimate mixing of wollastonite 7045 6563 6357 additives (both HAR and LAR) across the weldline, while 6000 5248 Tensile Modulus (MPa) Tensile glass fiber (GF) tends to align itself parallel to weldline, 4697 4634 causing weak interlayer bonding. Similar to GF, mica and 4000 30% GF 20% GF HAR Talc Talc Microcrystalline HAR Wollastonite LAR Wollastonite Mica HAR Suzorite Mica Suzorite Fine talc platelets also align parallel to weldline causing a Single-gated (no Weldline) – Dark bars Double-gated (with Weldline) – Light bars relatively weak point at the weldline. ASTM D638: Rate = 0.51 mm/min products. best performer, followed closely HAR by mica and talc wasin HDT obtained with HAR wollastonite being the enhancement significant still while GF, to compared testsHDT show slightly weaker performance for minerals HEAT DEFLECTION TEMPERATURE No Weldline No ADDITIVE ORIENTATION ADDITIVE Edgewise, 100mmSpan Edgewise, ISO 75at0.45MPa Rate=0.51mm/min ASTM D638: –Lightbars Weldline) (with Double-gated –Darkbars Weldline) (no Single-gated LAR NYGLOS® GLASS FIBER Heat deflection Temp. (HDT), ˚C NYGLOS® HAR Tensile Elongation, (%) 150 170 190 210 230 250 0 1 2 3 4 5 6 7 8 9 30% GF 30% GF 4.2 218 2.0 20% GF 20% GF 4.1 212 1.9 HAR Talc HAR Talc 1.7 206 0.4 Microcrystalline Talc Microcrystalline Talc 2.1 207 0.6 HAR Wollastonite HAR Wollastonite 7.3 211 2.5 LAR Wollastonite LAR Wollastonite 7.7 195 5.3 HAR Suzorite Mica Weldline At HAR Suzorite Mica 200 μm 20 μm 1.8 209 20 μm 0.4 Fine Suzorite Mica Fine Suzorite Mica 1.8 205 0.5 ISO 180 at 23°C – Dark bars ISO 180at23°C–Darkbars ASTM D256at23°C–Lightbars ISO 180 at 23°C – Light bars ISO 180at23°C–Lightbars ASTM D256at23°C–Darkbars HAR talc products giving the best performance. with HAR wollastonite, GF, to microcrystalline (LAR) and significantly improve spiral mold flow length compared flow injection molding shows that using minerals could limitations, which makes it hard to injection mold. Spiral Glass fiber filled is known PA6 have to melt flow IMPROVEMENT RHEOLOGY Spiral Mold Flow Length, mm Notched Izod Impact, (J/m) that 20% of GF filled formulations. provided the best Izod impact performance comparable to products wollastonite minerals, surface modified the Among loading. GF higher performance at increases in notched Izod impact performance as Izod impact Similar to strength, GF also provides aclear advantage IMPACT IZOD NOTCHED 300 350 400 450 500 100 120 140 wollastonite provides the best balance of HAR treated surface the minerals, Among talc provide the best stiffness. polymer properties while in HAR PA6, mica and fibre. fibre. glass chopped to compared formulations PA6 HAR talc significantly improve the rheology of HAR wollastonite, microcrystalline talc, and 20 40 60 80 0 30% GF 30% GF 356 105.0 115.3 20% GF 20% GF 407 61.5 68.2 HAR Talc HAR Talc 426 31.9 42.1 Microcrystalline Talc Microcrystalline Talc 452 35.8 45.2 HAR Wollastonite HAR Wollastonite 454 59.0 59.0 LAR Wollastonite LAR Wollastonite 368 64.7 56.3 HAR Suzorite Mica HAR Suzorite Mica 395 29.5 28.4 Fine Suzorite Mica Fine Suzorite Mica 404 32.8 32.1 Internal Method / Measurement Fixture (23°C-70°C) Fixture Internal Method/Measurement –Lightbars Direction Flow Cross –Darkbars Direction Flow CLTE, 10-5 °C Fixture Internal Method/Measurement –Lightbars Direction Flow Cross –Darkbars Direction Flow cross-flow direction beingsignificantly weaker. comparable performance only in the flow direction, with while GF followed HAR by wollastonite provide in both moldand CLTE) flow and cross flow directions, produce the best dimensional stability (lowest shrinkage HAR talc followed microcrystalline by talc and HAR mica GF in polyamide formulations. This study shows that Expansion) is adesirable performance for minerals and shrinkage (Coefficient and CLTE Linear of Thermal Improving dimensional stability as in reduced mold ISOTROPY AND STABILITY DIMENSIONAL 100 isotropic in two dimensions. dimensional aspect ratio, while talc and mica products are as GF and wollastonite cause anisotropy due their to one evident in thinner and larger parts.