BIPB (Bis(tert-butylperoxyisopropyl)benzene, CAS 25155-25-3) is a high-performance organic peroxide crosslinking agent revolutionizing polymer manufacturing. Known as the "odorless DCP," this white crystalline solid (melting point: 44–48°C) has become indispensable for industries demanding low-odor, high-efficiency vulcanization and controlled polymer degradation. With the molecular formula C₂₀H₃₄O₄ and molecular weight of 338.48 g/mol, BIPB combines unique chemical properties with versatile applications across rubber, plastics, and specialty polymers.
Chemical Structure and Properties
BIPB decomposes at its 1-minute half-life temperature of 182°C, generating free radicals that initiate crosslinking. Unlike traditional peroxides like DCP (Dicumyl Peroxide), BIPB produces volatile, low-odor decomposition products:
Acetone
Methane (CH₄)
tert-Butanol
This contrasts sharply with DCP, which yields pungent and hazardous acetophenone. BIPB’s higher theoretical active oxygen content (9.45% vs. DCP’s 5.92%) enables lower dosage requirements—typically 2/3 of DCP’s loading for equivalent crosslinking density. Its density of 1.63 g/mL at 25°C and low water solubility (0.1 g/100 mL) facilitate handling in industrial processes.
Versatile Industrial Applications
1. Rubber and Elastomer Vulcanization
BIPB is the crosslinker of choice for:
EPDM (car seals, roofing membranes)
Silicone Rubber (medical devices, gaskets)
Chlorinated Polyethylene (CPE)
Hydrogenated Nitrile Rubber (HNBR)
In EPDM, BIPB minimizes compression set and enhances heat resistance. However, its decomposition products may cause "blooming" (surface crystallization) due to poor compatibility with EPDM. Solutions include:
Adding PEG 4000 to improve compatibility
Blending with co-agents (e.g., triallyl isocyanurate)
2. Foams and Plastics
EVA Foam: Critical for producing low-odor yoga mats, shoe soles, and packaging.
Controlled Rheology Polypropylene: Degrades PP to narrow molecular weight distribution, enhancing melt flow for fibers and thin-wall injection molding.
Polystyrene: Acts as a high-conversion initiator for bulk polymerization.
3. Wire and Cable Insulation
BIPB’s low volatility makes it ideal for heat-resistant, halogen-free insulation in automotive and aerospace cables.
Performance Advantages Over DCP
Property BIPB DCP
Odor Low/None Strong, pungent
Decomposition Byproducts Acetone, CH₄, t-butanol Acetophenone
Active Oxygen 9.45% 5.92%
Typical Dosage ~1.5–3 phr ~2–4.5 phr
EPDM Blooming Possible Rare
BIPB matches DCP in mechanical properties (tensile strength, elongation) while outperforming it in high-temperature compression resistance. Its superior scorch safety allows safer processing at 135°C before crosslinking initiates at 175°C.
Safety and Handling Protocols
Classified as a 5.2 oxidizer (UN 3106), BIPB requires strict handling:
Storage: Below 30°C in airtight containers, separated from acids, reducers, and flammables.
Transportation: Avoid heat, shock, and sunlight; use Packing Group II compliance.
Fire Response: Use foam or dry chemical extinguishers for small fires; large fires require professional suppression.
Personal protective equipment (PPE)—gloves, goggles, and flame-retardant clothing—is mandatory during handling.
Innovations and Market Trends
The global push for eco-friendly materials has driven BIPB adoption:
Automotive: Replaces DCP in cabin seals (reducing "new car smell" VOCs).
Medical: Silicone catheters and implants leverage BIPB’s non-toxic byproducts.
Consumer Goods: EVA foam toys (e.g., puzzle mats) meet stringent EU odor regulations.
Manufacturers like Wuhan Kemike (96% purity grade) and Shandong suppliers dominate production, with prices ranging from $10–580/kg depending on purity and volume.
Conclusion: The Future of Crosslinking
BIPB (CAS 25155-25-3) represents the next evolution in polymer modification—balancing performance, safety, and environmental compliance. Its unmatched odor profile, efficiency, and versatility in rubber vulcanization, foam expansion, and polymer degradation position it as a cornerstone of sustainable manufacturing. As regulations tighten and consumer demand for low-VOC products grows, BIPB will continue displacing traditional peroxides across automotive, medical, and consumer sectors.
For formulation support or regulatory documentation (MSDS, TSCA/REACH compliance), consult suppliers like Sigma-Aldrich, Wuhan Kemike, or Thermo Fisher Scientific.