Guangzhou Kingfa Science & Technology Co., Ltd. supplies GFABS-10, GFABS-20, and GFABS-30 as short-glass-fiber-reinforced acrylonitrile-butadiene-styrene injection-molding compounds. The numerical suffix denotes the nominal glass fiber mass fraction: 10%, 20%, and 30%. Under ISO 1043-1, the formal designations are ABS-GF10, ABS-GF20, and ABS-GF30; under ISO 11469, molded articles may be marked with those symbols. The matrix is a grafted ABS terpolymer. The reinforcement is silane-sized short glass fiber with typical chopped strand length of 3–4.5 mm and filament diameter of 10–14 μm; compounding in a co-rotating twin-screw extruder reduces the mean fiber length to 0.2–0.5 mm. The retained fiber length distribution has a stronger effect on tensile strength and impact than the nominal loading alone. The series is specified where stiffness, heat deflection temperature, and creep resistance must exceed unfilled ABS while maintaining lower moisture uptake and lower density than glass-fiber-reinforced polyamide alternatives. The presence of glass fiber alters injection pressure, screw recovery, surface orientation, and screw/barrel wear behavior; operational boundaries are therefore narrower than for unfilled ABS.

How Do the Three Fiber Loadings Shift the Mechanical Response of ABS?

The glass fiber mass fraction operates as a rigid dispersed phase in a ductile thermoplastic matrix. Increasing glass fiber content from 10% to 30% raises density, tensile modulus, flexural modulus, and heat deflection temperature, but reduces notched Izod impact because fiber ends act as stress concentrators and shorten the ligament length between particles. Surface finish also becomes more fiber-dominated as the filler fraction increases because the polymer-rich skin layer becomes thinner and glass fibers are exposed at the advancing melt front. The following ranges are representative of short-glass-fiber-reinforced ABS systems reported in technical literature; they are not a substitute for lot-specific values from the supplier’s certificate of analysis.

The fiber-matrix interphase, controlled by the silane coupling layer on the glass fiber, governs stress transfer and long-term hydrolysis resistance. Unsized or poorly coupled glass fibers yield lower tensile strength at the same fiber mass fraction because interfacial debonding occurs before matrix yielding. In wet-heat service, the interphase can absorb water and lose siloxane bond integrity; property loss is therefore a function of sizing chemistry and not solely the ABS base resin. Users requiring sustained hot-humidity performance should specify a silane system rated for hydrolytic stability and request tensile property retention at 85°C and 85% relative humidity, although published data for this specific configuration are limited.

Moisture control before melt processing is mandatory. GFABS-10/20/30 should be dried from a sealed moisture barrier bag to below 0.05% by weight, typically in a dehumidifying dryer with air dew point below −40°C, inlet temperature 80–90°C, and drying time 3–4 h. A hot-air hopper dryer alone is insufficient in production environments above 60% relative humidity because surface moisture readsorbs quickly. At the throat, hopper residence time should not exceed 30 min when the machine is idle; longer hold times allow moisture regain and increase the probability of splay marks in molded parts. Melt temperature measured by an air shot should remain between 230°C and 260°C. The lower half is assigned to 10% fiber grades and thin-walled parts; the upper half is limited to short residence times in thick sections where glass packing must be maximized. Above 260°C, the butadiene rubber phase in ABS begins thermo-oxidative degradation, producing discoloration and a drop in impact strength; below 220°C, melt viscosity increases to the point that glass fibers abrade the screw channel more aggressively due to high torque. Mold surface temperature is held at 50–80°C; for 30% glass fiber, the lower limit should be raised to 65°C to promote a resin-rich surface. Back pressure of 0.5–1.5 MPa is used to homogenize fiber distribution, but excessive back pressure shortens fiber length and lowers final modulus. Screw compression ratio is selected in the 2.0:1 to 2.5:1 band, with L/D of 20:1 to 25:1; a general-purpose ABS screw with a low compression ratio may produce uneven glass dispersion. Because the glass fiber is abrasive, bimetallic barrel liners, hard-faced check ring seats, and hardened screw tips are specified for campaigns exceeding 50,000–100,000 shots. Nozzle orifices should be 4–6 mm in diameter for medium shot weights; small orifices cause fiber bundling and pressure losses.

Common processing defects in GFABS-10/20/30 are fiber agglomerates, surface glass streaks, weld-line weakness, and burn marks from venting insufficiency. Glass agglomerates form when screw recovery is too fast or when regrind particle size varies; a mixing section or dispersive screw elements reduce agglomerates. Venting depth at the mold parting line should be 0.02–0.04 mm; insufficient venting produces black specks because trapped air reaches compression ignition temperatures. The melt front should advance at 200–500 mm/s in thin-wall sections to minimize exposed fiber, but gate velocity above 1000 mm/s can cause jetting. Splay or silver streaks usually indicate moisture; the granulate should be re-dried and the hopper seal checked. Sink marks around bosses are managed by gas-assisted packing or by core pin displacement, but gas channels must be designed to avoid fiber orientation disruption.

Rheological Response and Thermal Degradation Boundaries in Reinforced ABS

Melt viscosity of GFABS-10/20/30 is non-Newtonian and rises with fiber volume fraction. The apparent viscosity at a shear rate of 1000 s⁻¹ is typically 40–80% higher for 30% glass fiber than for the unfilled base resin, depending on fiber length distribution and coupling agent. This viscosity increase requires higher injection pressure and reduces flow-length-to-wall-thickness ratio in thin-wall tooling. Melt pressure at transfer may reach 80–140 MPa for multi-cavity tools with long flow paths. The butadiene rubber phase imposes a residence-time limitation: total cycle residence time should not exceed 5 min at 250°C, and startups after interruption should purge with unreinforced ABS before GFABS is reintroduced. When held above 260°C for more than 3 min, the material may yellow and generate styrene monomer, with notched impact strength loss of 15–30% because of rubber-phase crosslinking and chain scission. If regrind is used, the glass fiber is shortened, so the addition rate should not exceed 20–30% by weight of total shot mass; higher regrind fractions reduce modulus and increase property variability. Reprocessing also increases the fraction of fines and can raise melt temperature variability; therefore, regrind should be re-dried to the same moisture specification as virgin material.

Fiber orientation in the flow field creates anisotropic shrinkage that must be accounted for in tool design. With a single edge gate, shrinkage parallel to flow is lower than shrinkage perpendicular to flow because aligned glass fibers restrict contraction along their longitudinal axis. In unfilled ABS, the shrinkage difference is normally below 0.1%; in GFABS-30, the differential can exceed 0.2%, sufficient to cause warpage in flat covers. Tools dimensioned for unfilled ABS must be recut when converting to GFABS-10/20/30 because the absolute shrinkage is lower but the anisotropy is higher. Gate selection dominates orientation: a fan gate or film gate generates a more uniform flow front and reduces warpage, while a pin gate creates radial orientation and uneven shrinkage. Weld lines formed downstream of cores or multiple gates are fiber-poor and retain 40–70% of the bulk tensile strength; the retained percentage decreases as fiber loading increases. Sequential valve gating, overflow channels, or relocation of the weld line to low-stress regions is required. Rib design should use a thickness of 40–60% of the nominal wall; higher rib thickness causes sink marks because the shrinkage difference between the reinforced surface and the unreinforced core becomes visible. For close-tolerance parts, a post-molding conditioning step of 2–4 h at 80°C may be used to relax molded-in stress before dimensional inspection. Draft angles should be increased by 0.5 to 1.0 degree relative to unfilled ABS because glass-filled surfaces are stiffer and more resistant to ejection; ejector pins require larger contact area.

Relative to unfilled ABS, GFABS-10/20/30 increases tensile modulus by a factor of roughly 2–4, heat deflection temperature by 10–25°C, and density by 0.05–0.25 g/cm³, while decreasing notched impact by 20–60%. The coefficient of linear thermal expansion falls from 70–90 × 10⁻⁶ K⁻¹ for unfilled ABS to 20–35 × 10⁻⁶ K⁻¹ for 30% glass fiber, improving dimensional stability in metal-over-plastic assemblies. Compared with glass-fiber-reinforced polyamide 6 at equivalent fiber content, GFABS absorbs less moisture, typically below 0.3% at 50% relative humidity, while PA6-GF30 may reach 1.5–2.5%; therefore GFABS retains dimensions better in humid environments. Continuous-use temperature and chemical resistance are lower than PA6-GF30, especially against glycols and hot automotive coolants. Compared with glass-filled polypropylene, GFABS provides higher heat deflection temperature and lower mold shrinkage, but the polypropylene compounds offer lower density and better resistance to acids. Compared with PC/ABS blends, GFABS typically processes at lower melt temperature and may show lower notched impact at −30°C; however, the glass reinforcement raises stiffness beyond that of most unfilled PC/ABS grades. The selection among GFABS-10, GFABS-20, and GFABS-30 is therefore governed by the balance of stiffness, toughness, surface quality, and shrinkage tolerance in the part design.

When a Specified Flammability Rating or Food-Contact Status Is Required, the Fiber and Additive Package Must Be Declared

Glass fiber alters flammability behavior by changing melt flow, dripping, and char retention. Not all GFABS grades carry a flame-retardant classification; unreinforced ABS is commonly rated HB under UL 94 at 1.5 mm to 3.0 mm, but glass reinforcement can shift dripping characteristics, so any V-2, V-1, or V-0 claim must be supported by a specific UL file card and thickness range. For electrical and electronic applications, the compound may be evaluated according to IEC 60695-11-10. Under RoHS Directive 2011/65/EU, the homogeneous material must not exceed 0.1% by weight for lead, mercury, hexavalent chromium, polybrominated biphenyls, or polybrominated diphenyl ethers, and 0.01% for cadmium. Under REACH, Article 33 communication is required if any substance of very high concern exceeds 0.1% by weight per article. Food-contact status is not implicit in the base resin; migration testing under FDA 21 CFR 177.1020 or EU Regulation (EU) No 10/2011 requires disclosure of the glass fiber sizing chemistry, any processing aids, and colorants. Published data for Kingfa GFABS-10/20/30 in food-contact configurations are limited, so lot-specific declarations and migration testing are required before use.