EMS-Grivory Grilamid TR 55 LZ is a transparent amorphous polyamide 12 (nylon 12) injection-molding grade supplied in a dry, low-moisture packaging state. The “TR 55” designation identifies the amorphous transparent base resin; the “LZ” suffix identifies the flow-modified, low-viscosity injection-molding variant. The dry condition is a reference state for mechanical and thermal data, not a permanent service condition. In unopened packaging, residual moisture is maintained below 0.10 wt%. The grade is characterized by a dry density of 1.06 g/cm³ according to ISO 1183, a dry tensile modulus of 2200 MPa according to ISO 527-1/-2, and a dry notched Charpy impact strength of 8 kJ/m² according to ISO 179/1eA. Typical components include transparent automotive interior elements, cosmetic pump housings, medical device windows, sight glasses, and clear fluid reservoirs.

The product is positioned for applications requiring optical clarity, chemical resistance to non-polar hydrocarbons, and lower processing viscosity than standard transparent polyamide grades. The polyamide 12 backbone provides lower water uptake than PA 6 and PA 66, but the amorphous structure absorbs more water than semicrystalline PA 12. At 23 °C and 50% RH, equilibrium water absorption is approximately 1.7 wt%; saturation values reported by the supplier are higher. Because the dry data are not equivalent to conditioned service data, design calculations for humid environments must use moisture-conditioned values.

The dry grade is supplied with a defined processing window. Pre-drying is mandatory after exposure to ambient humidity above 60% RH for more than 30 min. The processing window is bounded at the lower end by melt temperature required for thin-wall filling and at the upper end by thermal degradation. The melt temperature range is 250–280 °C, and the mold temperature range is 40–80 °C. Residence time at melt temperature should not exceed 12 min. These boundaries create a critical processing band of approximately 30 °C; molders must balance fill pressure, optical clarity, and residence-time distribution.

What Engineering Data Define the Dry As-Molded Condition?

Table 1 lists the dry as-molded properties used for material selection and initial engineering calculations. The tensile values follow ISO 527-1/-2 specimen protocols. Impact values are obtained with edgewise Charpy specimens according to ISO 179/1eA for notched impact and ISO 179/1eU for unnotched impact. Thermal data follow ISO 75-1/-2 for deflection temperature under load and ISO 11357-1/-2 for glass transition temperature.

Table 1: Typical dry-as-molded properties of EMS-Grivory Grilamid TR 55 LZ

Property	Test method	Dry value
Density	ISO 1183	1.06 g/cm³
Water absorption, equilibrium at 23 °C, 50% RH	ISO 62	1.7 wt%
Water absorption, saturation	ISO 62	6.5 wt%
Tensile modulus, dry	ISO 527-1/-2	2200 MPa
Tensile stress at yield, dry	ISO 527-1/-2	85 MPa
Tensile strain at yield, dry	ISO 527-1/-2	6%
Tensile strain at break, dry	ISO 527-1/-2	>50%
Charpy notched impact strength, dry	ISO 179/1eA	8 kJ/m²
Charpy unnotched impact strength, dry	ISO 179/1eU	10 kJ/m²
Ball indentation hardness	ISO 2039-1	170 MPa
Glass transition temperature, dry	ISO 11357-1/-2	155 °C
Deflection temperature under load, 1.80 MPa	ISO 75-1/-2	125 °C
Deflection temperature under load, 0.45 MPa	ISO 75-1/-2	135 °C
Coefficient of linear thermal expansion	ISO 11359-1/-2	90 × 10−6 K−1
Total luminous transmittance, 2 mm	ASTM D1003	92%
Haze, 2 mm	ASTM D1003	2%
Flammability rating, 1.6 mm	UL 94	HB

The dry glass transition temperature of 155 °C is a characteristic value for the amorphous phase; no melting point is reported because the material is noncrystalline. Deflection temperature under load at 1.80 MPa is 125 °C, which places the grade below the upper continuous-use temperature of semicrystalline PA 12 but within the range required for many interior and consumer components. The coefficient of linear thermal expansion of 90 × 10⁻⁶ K⁻¹ is higher than that of glass or metal; assemblies with metal inserts require design allowances for differential expansion. Optical data are thickness-dependent. The 92% total luminous transmittance and 2% haze values apply to polished 2 mm plaques; thicker sections reduce transmission due to optical path length, and lower mold surface quality increases haze.

Moisture uptake alters the dry property set. Conditioned tensile modulus is typically near 2000 MPa, and notched Charpy impact strength can increase to approximately 10 kJ/m². The shift is not a defect; it is the expected plasticizing effect of absorbed water. For load-bearing calculations at service humidity above 60% RH, the conditioned values should be used instead of dry as-molded values.

Processing Window, Drying Thresholds, and Barrel Residence Limits

The processing window is constrained by the need to keep melt temperature high enough for thin-wall filling while avoiding thermal degradation. Pre-drying in a desiccant dryer is required when the sealed bag has been opened for more than 30 min at ambient relative humidity above 60% RH. Moisture contents above 0.10 wt% cause hydrolysis during plastication, producing splay, surface haze, and loss of impact strength. Drying is typically conducted at 80 °C for 4–12 h with a desiccant-bed dew point below −30 °C.

Table 2: Recommended injection-molding conditions for dry EMS-Grivory Grilamid TR 55 LZ

Parameter	Setpoint or range
Drying temperature	80 °C
Drying time	4–12 h
Residual moisture before molding	<0.10 wt%
Melt temperature	250–280 °C
Mold temperature	40–80 °C
Maximum residence time at melt temperature	12 min
Hot runner temperature	250–270 °C

Barrel temperature profiling is typically rear 240–250 °C, center 250–260 °C, front 260–270 °C, and nozzle 250–270 °C. Melt temperature above 280 °C produces measurable yellowing and chain scission. Residence time at melt temperature should not exceed 12 min; long residence-time distribution in hot runner dead spots should be eliminated. Mold temperatures in the 40–80 °C range influence transparency and molded-in stress. Higher mold temperatures improve optical quality and reduce orientation stress but extend cycle time. Lower mold temperatures may produce higher haze and increased warpage after post-mold moisture uptake.

Hot runner systems require open-pipe or valve-gated designs with no dead spots. Heated sprue bushings and long hot runner channels increase residence-time distribution and can degrade the material even when barrel setpoints remain within the specified range. Injection speed is medium to high to avoid hesitation marks and surface flow lines. Back pressure should be kept low to moderate; excessive shear heating can raise melt temperature above the degradation threshold. Screw recovery should avoid high screw rotation speeds above those recommended for the screw diameter in use.

Thin-wall components with wall sections down to 0.8 mm can be filled when melt temperature is maintained above 260 °C and mold temperature is kept in the upper half of the specified range. Published data for wall sections below 0.8 mm are limited; molding trials with instrumented cavity-pressure sensors are recommended for such configurations.

Optical performance is evaluated on polished plaques at 2 mm thickness. The total luminous transmittance of 92% and haze of 2% per ASTM D1003 are not maintained if mold surface finish is below SPI A-2 or if moisture is present during molding. The amorphous structure eliminates spherulitic scattering, but optical path length in sections above 4 mm reduces measured transmission. Chemical resistance is strongest with non-polar aliphatic hydrocarbons, diesel fuel, and many cosmetic ester formulations. The material is less resistant to strong acids, chlorinated solvents, and lower alcohols at elevated temperature. Environmental stress cracking under load should be evaluated according to ASTM D543 or ISO 22088-3, particularly for parts exposed to alcohol-based disinfectants or aggressive cosmetic formulations. Components with continuous exposure to aqueous solutions above 60 °C require humidity-conditioned design data. Transparent fluid reservoirs, sight glasses, and medical device housings are specified with dry tensile and impact values only as incoming resin acceptance criteria. Drawing-level performance values should include conditioned service conditions because the shift in modulus and impact is large enough to affect snap-fit and press-fit designs. The low water uptake of the polyamide 12 backbone relative to PA 6 and PA 66 is a key selection parameter, but the amorphous structure still absorbs enough moisture to alter dimensions by the equilibrium absorption value. Regulatory status is grade-specific. Food-contact and medical applications must be verified against the supplier’s current certificates. Relevant regulatory frameworks include EU Regulation 10/2011, FDA 21 CFR 177.1500, REACH, and RoHS. The resin supplier does not provide final device certification; biocompatibility testing such as ISO 10993-1 is application-specific and depends on processing, cleaning, and sterilization history.

When Transparent Polyamide 12 Replaces Polycarbonate or PMMA

The selection of Grilamid TR 55 LZ over polycarbonate is typically driven by stress-crack resistance in contact with cosmetics, plasticizers, and alcohols. Polycarbonate offers higher tensile modulus and similar heat deflection, but can fail by environmental stress cracking in certain formulations. The dry tensile modulus of this grade is 2200 MPa, while optical polycarbonate is generally above 2300 MPa; the small difference is less significant than the chemical compatibility requirement. Polycarbonate also has higher notched impact strength at room temperature, so drop-impact performance should be evaluated separately.

Compared with PMMA, this transparent polyamide 12 grade provides lower surface hardness and lower UV stability, but higher notched impact strength and better resistance to many non-polar chemicals. PMMA grades can drop below 2 kJ/m² in notched Charpy impact at room temperature, while this grade remains near 8 kJ/m² dry. The difference is relevant for snap-fit closures and transparent housings subject to assembly or drop loading.

Compared with standard semicrystalline PA 12, the transparent grade replaces crystallinity with amorphous chain packing. This removes haze and spherulitic light scattering but reduces the upper continuous-use temperature under load. The LZ modification lowers melt viscosity relative to standard TR 55, permitting shorter filling times and reduced injection pressure in thin-wall sections. Standard TR 55 remains preferred where thicker sections or profile extrusion require higher melt strength. Unlike glass-reinforced transparent grades, this unreinforced grade does not achieve high stiffness; it should not be specified as a structural replacement for glass-filled polycarbonate or glass-filled polyamide.

Within the EMS-Grivory TR series, TR 55 LZ is positioned as the low-viscosity transparent polyamide 12 grade. Grades with higher glass transition temperature are available where higher heat resistance is required. Comparative data for the LZ suffix are limited in published literature; the property and processing tables above should be verified against the current supplier datasheet. Typical incoming inspection criteria for transparent cosmetic pump housings and light guides cite ISO 527-1/-2 tensile modulus and ASTM D1003 haze.