Modified ABS refers to acrylonitrile-butadiene-styrene (ABS) polymer that has been chemically or physically altered to enhance specific properties beyond its standard form. This modification process involves adding fillers, flame retardants, or other additives, or blending it with other polymers to address limitations in standard ABS, such as low heat resistance, flammability, or insufficient mechanical strength. Below is a detailed comparison highlighting the key differences:
1. Mechanical Properties
Standard ABS:
- Offers balanced toughness and rigidity, with tensile strength typically around 35–45 MPa and impact resistance of 15–25 kJ/m² (Izod). However, it lacks the strength required for heavy-duty applications.
Modified ABS:
- Reinforced ABS (e.g., with glass/carbon fiber): Tensile strength can exceed 80 MPa, and flexural modulus increases by 100–200% . For example, glass fiber-reinforced ABS (ABS-GF) with 20–40% fiber content achieves 70–100 MPa tensile strength and improved dimensional stability .
- High-Impact ABS (HIPS): Impact resistance can reach 50–80 kJ/m², making it suitable for crash-resistant components like automotive bumpers .
2. Thermal Performance
Standard ABS
- Softens at 80–100°C (heat deflection temperature, HDT) and is unsuitable for high-temperature environments.
Modified ABS:
- Heat-Resistant ABS: HDT increases to 100–120°C by incorporating heat-stable monomers like α-methylstyrene or blending with SMA (styrene-maleic anhydride).
- Flame-Retardant ABS (FR-ABS): While HDT may drop slightly to 85–95°C, it achieves UL 94 V-0 rating (self-extinguishing) through halogenated or phosphorus-based additives.
3. Chemical and Environmental Resistance
Standard ABS
- Resistant to oils and solvents but degrades in prolonged UV exposure, leading to brittleness.
Modified ABS:
- UV-Stabilized ABS: Incorporates additives like ASA (acrylonitrile-styrene-acrylate) to withstand outdoor use, with color stability for 5+ years.
- Chemical-Resistant ABS: Enhanced resistance to acids/alkalis via copolymerization or filler addition (e.g., for industrial pipes).
4. Electrical and Surface Properties
Standard ABS
- Insulating with high surface resistivity (>10¹⁴ Ω), prone to static buildup.
Modified ABS:
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Antistatic ABS: Surface resistivity drops to 10⁶–10⁹ Ω by adding carbon black, metal powders, or permanent antistatic agents, critical for electronics packaging.
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High-Gloss ABS: Achieves 80–90% gloss (60° angle) through controlled rubber particle size or additives, used in luxury appliances.
