Grantee Research Project Results

Final Report: Biorenewable Rubber Anti-Degradants

EPA Contract Number: 68HERC25C0030
Title: Biorenewable Rubber Anti-Degradants
Investigators: Mujkic, Monika
Small Business: Tetramer Technologies LLC
EPA Contact: Richards, April
Phase: I
Project Period: December 16, 2024 through June 15, 2025
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2025) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR)

Description:

This project aims to develop bio-based anti-degradants for rubber compounds as sustainable, environmentally safer alternatives to conventional petroleum-derived additives such as 6PPD. While traditional anti-degradants are effective, their degradation can produce harmful byproducts like 6PPD-quinone, which has been linked to serious environmental concerns, including acute toxicity to aquatic life.

The research focuses on synthesizing and evaluating renewable, non-toxic additive systems that offer comparable or improved protection against rubber degradation from ozone, heat, and oxidation. Key activities include the design of anti-degradants from renewable feedstocks, their incorporation into rubber formulations, mechanical and aging performance testing, and comparative analysis against commercial standards. The environmental impact and toxicity of both the additives and their degradation products are also assessed.

By advancing safe and effective alternatives, this project supports the shift toward sustainable materials in the rubber industry and aligns with emerging regulatory and environmental priorities.

Summary/Accomplishments (Outputs/Outcomes):

A bio-based anti-degradant was successfully synthesized and structurally confirmed using FTIR spectroscopy, while thermogravimetric analysis (TGA) demonstrated that the material possessed sufficient thermal stability for rubber processing conditions. The additive was incorporated into a commercially relevant sidewall tire rubber formulation and processed using a custom-built curing setup with heated aluminum molds. A 15-minute vulcanization protocol was optimized to produce uniformly cured samples suitable for performance testing.

Ozone aging tests were conducted under controlled conditions (168 hours at 40°C and 50 pphm ozone, static exposure). No visible signs of surface cracking, pitting, or discoloration were observed in any of the samples, including control samples without added antioxidants. Additionally, FTIR analysis of rubber surfaces before and after ozone exposure showed no detectable chemical changes or evidence of oxidation. These findings suggest that the applied ozone conditions may not have been sufficiently severe to induce observable aging or degradation, limiting the ability to assess the relative performance of the synthesized anti-degradant.

However, the absence of surface oxidation or degradation—even in untreated controls—may also indicate that the newly synthesized bio-based additive provided a degree of protection under mild conditions. While these results are not conclusive, they are promising and support further investigation. To fully evaluate the protective properties of the anti-degradant, additional testing under more rigorous ozone exposure and environmental stress conditions will be necessary.

Commercialization

Initial outreach to potential customers and industry stakeholders has begun, with several productive conversations taking place during the project. These discussions revealed strong and growing interest in sustainable alternatives to conventional rubber additives, particularly due to increasing regulatory and environmental concerns surrounding compounds like 6PPD. Industry contacts expressed openness to evaluating bio-based solutions and emphasized the need for safer, effective anti-degradants that do not compromise performance.

In addition to performance, cost competitiveness and ease of implementation were identified as key factors for market adoption. The synthesized anti-degradant is designed to be compatible with existing rubber processing workflows, minimizing the need for changes to manufacturing infrastructure. These early interactions support continued development, scale-up, and validation of the environmentally benign anti-degradant, with a focus on meeting industry requirements for safety, performance, and commercial viability.

Conclusions:

This project successfully demonstrated the synthesis and initial evaluation of a renewable anti-degradant for rubber applications. While aging tests were inconclusive under current conditions, the material showed good thermal stability and compatibility with commercial rubber formulations. Early industry engagement indicates strong interest in safer, sustainable alternatives. Continued development and more rigorous performance testing are planned to advance commercialization and validate effectiveness.