Designation DG-MG94 from Tianjin Dagu Chemical Co., Ltd. refers to a pelletized acrylonitrile-butadiene-styrene copolymer produced for conventional injection molding. The grade is classified under ISO 19062-1 as an ABS injection-molding resin, and supplier certificates of analysis typically report density, melt mass-flow rate, tensile stress at yield, flexural modulus, notched impact strength, heat deflection temperature and Vicat softening temperature. The polymer consists of a polybutadiene rubber phase dispersed in a styrene-acrylonitrile matrix; the rubber phase contributes room-temperature impact resistance, while the continuous SAN phase contributes surface hardness, gloss and chemical resistance. DG-MG94 is selected for automotive interior trim, appliance fascias, electrical enclosures, vacuum cleaner bodies and consumer durables where gloss retention, melt processability and intermediate impact toughness are specified. The grade is not designated as a low-temperature impact material and is not marketed as an electroplating substrate. Published data for DG-MG94 in electroplating configurations is limited, and substitution into plating tooling is not recommended without first-run adhesion testing under the processor’s etch chemistry.

Representative property values from manufacturer technical literature are summarized in the matrix below. These values are not lot-specific limits. Certification for a given shipment should be obtained from the supplier’s batch certificate.

Representative property matrix for DG-MG94

Property	Test method	Unit	Representative value
Density	ISO 1183-1	g/cm³	1.05
Melt mass-flow rate at 220 °C/10.0 kg	ISO 1133-1	g/10 min	18
Tensile stress at yield	ISO 527-2	MPa	46
Tensile elongation at break	ISO 527-2	%	20
Flexural modulus	ISO 178	MPa	2400
Flexural strength	ISO 178	MPa	70
Charpy notched impact strength at 23 °C	ISO 179-1/1eA	kJ/m²	24
Vicat softening temperature, 50 N load	ISO 306/B50	°C	99
Heat deflection temperature, 0.45 MPa load	ISO 75-2/B	°C	95
Mold shrinkage	ISO 294-4	%	0.4–0.6

In practice, DG-MG94 is used where surface appearance and intermediate impact requirements intersect. The room-temperature Charpy value of 24 kJ/m² at 23 °C is typical of a medium-impact injection-molding ABS, but it does not guarantee ductile failure at low temperature. The polybutadiene phase undergoes a glass transition below −60 °C; however, parts carrying a specified minimum notched impact below −20 °C should not be qualified with DG-MG94 unless lot-specific low-temperature Charpy data are supplied by the manufacturer.

What process controls prevent moisture-induced surface defects and chain scission in DG-MG94?

ABS resins are hygroscopic, and DG-MG94 pellets absorb surface and internal moisture during warehouse storage and hopper transfer. A desiccant-bed dryer with a dew point of −30 °C or lower is recommended. Pre-drying at 80 °C for 2–4 h reduces pellet moisture below 0.10%; higher temperature or residence beyond 6 h can yellow the grade and shift the melt index. In plants with relative humidity above 60%, sealed hopper loading and nitrogen-purged feed throats are used. Wet pellets produce gas streaks, silver streaks and surface weld-line weakness in parts. Moisture-induced molecular weight reduction during plastication is observed as a drop in melt viscosity and a decrease in notched impact value. The recommended melt temperature measured at the nozzle is 210–250 °C; the barrel profile from rear to nozzle is typically set at 180–200 °C, 200–220 °C, 210–240 °C and 210–230 °C. Prolonged residence above 260 °C or residence times above 10 min should be avoided because thermal degradation releases volatile styrene and reduces mechanical integrity.

Recommended start-up conditions for DG-MG94 on a conventional hydraulic injection press

Parameter	Set range	Unit	Control note
Pre-drying temperature	80	°C	Desiccant dryer, dew point −30 °C or lower
Pre-drying time	2–4	h	Target moisture below 0.10%
Melt temperature at nozzle	210–250	°C	Avoid sustained temperature above 260 °C
Mold temperature	40–80	°C	Higher mold temperature raises surface gloss
Injection pressure	70–120	MPa	Cavity pressures commonly 40–80 MPa
Hold pressure	50–70% of peak injection	—	Maintain cushion at 3–6 mm
Back pressure	0.5–1.5	MPa	Do not exceed 2.0 MPa on general-purpose screw
Screw speed	60–100	rpm	For 20:1 L/D general-purpose screw

Injection Pressure Drops, Packing and Gate Freeze-Off in Thin-Wall Tooling

For wall sections between 1.5 mm and 3.0 mm, cavity pressures commonly fall between 40 MPa and 80 MPa. Hydraulic injection pressure at the ram is set in the range 70–120 MPa, with hold pressure at 50–70% of the peak injection pressure. A cushion of 3–6 mm is maintained to permit packing. Melt temperature at the upper end of the range improves pressure transmission, but increases gate blush and part gloss variation. Mold temperatures between 40 °C and 80 °C are used; water-cooled molds at the lower end of the range shorten cycle time but produce lower surface gloss. To control gate freeze-off, subgate diameters below 1.0 mm should be avoided because the grade’s melt viscosity can freeze before packing is complete, causing sink marks and poor surface replication. On hot-runner systems, manifold temperature should be held within 5 °C of the nozzle set point to avoid dead sections.

Mechanical response in molded plaques is evaluated according to ISO 527-2 and ISO 178. The tensile stress at yield for DG-MG94 is approximately 46 MPa; flexural modulus near 2400 MPa indicates stiffness typical of medium-impact ABS rather than polycarbonate blends. The Charpy notched impact value of 24 kJ/m² at 23 °C supports ductile failure in standard ambient ABS regimes, but not at low temperature. Because the butadiene phase in ABS undergoes a glass transition below −60 °C, low-temperature ductility is not guaranteed by room-temperature notched tests.

When DG-MG94 Replaces Higher-Flow DG-417 in Multi-Cavity Applications

DG-MG94 differs from higher-flow Dagu ABS grades such as DG-417 primarily in melt viscosity and surface appearance. DG-417 is formulated for reduced melt pressure drop and faster filling of thin-walled parts; DG-MG94 is formulated for higher surface gloss and intermediate impact strength. Substitution into existing DG-417 tooling requires a process audit because DG-MG94 exhibits a lower melt mass-flow rate and may require an increase in melt temperature or injection speed. The change in melt index also alters pressure-limited cavity filling in tools with long flow paths. Direct drop-in replacement without process adjustment has produced short shots, greater orientation, and uneven gloss in production-scale trials on a 120-ton hydromechanical press with a 20:1 L/D general-purpose screw. The grade should not be combined with amine-containing antioxidant packages that accelerate yellowing, and it is not recommended for solvent-bonded assemblies using ketone-based adhesives unless stress-cracking resistance is verified after assembly.

Regulatory compliance is governed by the specific lot and the geometry of the molded article. DG-MG94 is normally assessed for food-contact suitability only when the supplier certifies the grade against EU 10/2011 or FDA 21 CFR 180.920 for a defined end use. The stock material is not presumed suitable for direct food contact. Flame rating is typically HB under UL 94; for ignition resistance in electrical enclosures, a V-series rating should not be inferred. The grade is compatible with standard ABS masterbatch carriers based on SAN or polystyrene for colouring, but increasing filler or flame-retardant additives above 2.0 wt% has been observed in compounding studies to reduce melt flow by more than 10% and to shift notched impact values, so additive loadings require revalidation. Surface application of antistatic quaternary ammonium additives above 0.2% addition produced slip migration on plaque surfaces in humidity storage, indicating an incompatibility boundary for this grade.