Product Overview

AMSD, or Alpha-Methyl Styrene Dimer, is chemically known as 2,4-diphenyl-4-methyl-1-pentene (CAS No. 6362-80-7). It is a colorless, transparent liquid used as an environmentally friendly, odorless molecular weight regulator (chain transfer agent) in polymer polymerization.

Bais Technology has overcome technical barriers, completed pilot-scale trials, and achieved industrial production of AMSD.

1. Working Principle
(1) AMSD works via chain transfer. During free radical polymerization, a growing chain radical abstracts an atom from AMSD, terminating into a "dead" polymer chain, while AMSD forms a new active radical that reinitiates monomer polymerization. The overall effect: reduced molecular weight and narrower molecular weight distribution, with essentially no impact on polymerization rate.
(2) Compared with increasing initiator dosage to lower molecular weight, AMSD enables precise molecular weight control without changing polymerization rate, avoiding risks such as runaway reactions.
(3) Advantages over traditional sulfur-based regulators:
Traditional regulators are mainly thiols (e.g., NDM, TDM), which are toxic, odorous, environmentally hazardous, and classified as dangerous chemicals with high transport and storage costs.

2. Advantages of AMSD
(1) Sulfur-free and odorless: improves workplace environment and product sensory quality.
(2) Safe and eco-friendly: FDA-approved; compliant with REACH, ROHS, and other international regulations.
(3) Performance enhancement: reduces chain branching, yields more uniform and narrower molecular weight distribution, and improves transparency, weather resistance, and mechanical properties.
(4) Safe application: not classified as a dangerous chemical; no special transport or storage requirements.

3. Main Applications
AMSD is widely used in over ten polymer systems:
(1) Acrylic resins: molecular weight control; improves leveling, viscosity uniformity, transparency, and weather resistance.
(2) Styrenic resins: molecular weight control for PS, EPS, SAN, ABS, HIPS, etc.
(3) Latex polymerization: SBR, NBR, styrene-acrylic latex, etc.
(4) Processing aids: intrinsic viscosity control in ACR production.
(5) EVA polymers: reduces fish-eye formation and haze.
(6) Rubber modification: improves melt flow.
(7) PE crosslinking: serves as a scorch inhibitor.
(8) PVC processing: plasticizer replacement for DOP; improves processability.
(9) Also used in pharmaceuticals, food-contact materials, lubricants, fragrances, coatings, inks, and other high-end fields.

4. Market Size and Supply Landscape
According to Global Info Research, the global AMSD market was approximately USD 31.78 million in 2025 and is projected to reach USD 42.08 million by 2031, with a CAGR of about 4.79%. The plastics industry is the largest downstream market, accounting for about 47%.

5. Development Trends
With tightening global environmental regulations and carbon neutrality goals, AMSD is rapidly gaining traction as a green alternative to traditional sulfur-based regulators. Future directions include expansion from conventional plastics and coatings into high-end fields such as pharmaceuticals and food-contact materials, as well as emerging applications in new energy battery materials and semiconductor materials.

Bais Chemical Technology has an independent patented R&D team and a complete production and quality inspection system, providing full-process technical support from production to application. The company has built a complete high-end production line capable of stably supplying products with purity ≥98%. Trial-tested by domestic and international customers with consistent positive feedback, it is a reliable and stable choice.