Functional Additives in Automotive Polymer Matrices: Compatibility, Mechanisms, and Industry Challenges

This review supports formulation engineers in designing compatible and regulation-compliant additive systems. The integration of functional additives into polymer matrices plays a pivotal role in tailoring material properties to meet the demanding performance, safety, and sustainability criteria of the automotive industry. Key findings highlight that (1) optimal additive loadings are critical for balancing performance and mechanical integrity; (2) HALS and benzotriazole-based UV stabilizers extend service life by up to 3000 h in accelerated weathering without modulus loss; (3) bio-based plasticizers such as ESO and ATBC reduce migration rates by 30-40% compared to conventional phthalates; (4) phosphorus-based flame retardants and zinc borate synergistically achieve UL-94 V-0 ratings with minimal smoke release. This work introduces an integrative mapping of additive-polymer interactions under real-world conditions, coupled with synthesis tables that provide multi-criteria evaluations of performance, limitations, and sustainability-tools not present in prior literature. In contrast to previous reviews, this work introduces an integrative mapping of additive-polymer interactions under real-world automotive stressors, explicitly linking performance, compatibility, regulatory compliance, and sustainability. In addition, a series of synthesis consolidate multi-criteria evaluations-covering functional performance, technical limitations, regulatory risks, and sustainability potential-which provide practitioners with a decision-support tool not found in prior literature. These features constitute the primary methodological and practical contributions of this review. This review uniquely integrates an "evidence strength" assessment into synthesis tables and develops an integrative mapping of polymer-additive systems, offering actionable guidelines that go beyond prior literature reviews.