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The nitroxide-mediated polymerization (NMP) of isoprene (I) initiated by the poly(ethylene-stat-butylene)-(SG1)2 dialkoxyamine (PEB-(SG1)2) at 115 °C in 50 vol% pyridine led to cis-1,4-rich poly(isoprene)s (PIs), exhibiting Mn,GPC = 52–59 K (PI equivalents) and Ð = 1.46–1.59. S-I-S triblock copolymers (S = styrene, Mn,GPC = 95–109 K, Ð = 2.11–2.29, FS = 0.30–0.49) were synthesized via subsequent S chain-extensions in bulk at 115 °C from these PI-(SG1)2 macro-initiators. A micro-phase separation, exhibiting possibly a cylindrical or lamellar morphology, was observed by atomic force microscopy for an S-I-S having FS = 0.30. Tensile strength at break σB = 2.8–4.1 MPa and elongation at break eB ~ 375–450% were measured for S-I-S samples with FS = 0.30–0.38. The substitution of the PS outer segments by more rigid segments rich in isobornyl methacrylate (IBOMA) units allowed to improve the stress–strain properties, with σB = 11.4 ± 0.6 MPa and eB = 1356 ± 214%. This IBOMA-I-IBOMA type copolymer also displayed an upper service temperature greater than 150 °C.

β-Myrcene (My), a natural 1,3-diene, and isobornyl methacrylate (IBOMA), from partially bio-based raw materials sources, were copolymerized by nitroxide-mediated polymerization (NMP) in bulk using the SG1-based BlocBuilder™ alkoxyamine functionalized with an N-succinimidyl ester group, NHS-BlocBuilder, at T = 100 °C with initial IBOMA molar feed compositions fIBOMA,0 = 0.10–0.90. Copolymer reactivity ratios were rMy = 1.90–2.16 and rIBOMA = 0.02–0.07 using Fineman–Ross, Kelen–Tudos and non-linear least-squares fitting to the Mayo–Lewis terminal model and indicated the possibility of gradient My/IBOMA copolymers. A linear increase in molecular weight versus conversion and a low dispersity (Đ ≤ 1.41) were exhibited by My/IBOMA copolymerization with fIBOMA,0 ≤ 0.80. My-rich and IBOMA-rich copolymers were shown to have a high degree of chain-end fidelity by performing subsequent chain-extensions with IBOMA and/or My, and by 31P NMR analysis. The preparation by NMP of My/IBOMA thermoplastic elastomers (TPEs), mostly bio-sourced, was then attempted. IBOMA-My-IBOMA triblock copolymers containing a minor fraction of My or styrene (S) units in the outer hard segments (Mn = 51–95 kg mol−1, Đ = 1.91–2.23 and FIBOMA = 0.28–0.36) were synthesized using SG1-terminated poly(ethylene-stat-butylene) dialkoxyamine. The micro-phase separation was suggested by the detection of two distinct Tgs at about −60 °C and +180 °C and confirmed by atomic force microscopy (AFM). A plastic stress–strain behavior (stress at break σB = 3.90 ± 0.22 MPa, elongation at break eB = 490 ± 31%) associated to an upper service temperature of about 140 °C were also highlighted for these triblock polymers.

This contribution addresses the challenging investigation of the chemical mechanisms occurring at the carbon fiber-matrix interface of carbon fiber-reinforced polymer (CFRP) composite materials cured out-of-autoclave. A high energy radiation curing method (electron-beam) was used to initiate free radical polymerization of acrylate-based matrices. Comparison with state-of-the-art thermally cured composites reveals the lower transverse mechanical properties of the radiation-cured CFRP composites. To improve the interfacial layer, several points related to the polymerization at the interphase have been investigated. Notably, the influence on the polymerization of acrylate matrices of the chemical functional groups present at the carbon fiber surface and its graphite-like properties are discussed using representative molecules. It is shown that these additives exhibit strong inhibiting effects, whereas thiol groups efficiently sensitize the initiation mechanisms and undergo transfer reactions. Moreover, it is discussed that graphite-like molecules affect the matrix polymerization and the mechanical properties of the composites. An adapted solution is proposed.

This paper concerns engineered composites integrating metallic particles to enhance thermal and electrical properties. However, these properties are strongly dependent on the forming process itself that determines the particle distribution and orientation. At the same time, the resulting enhanced thermal properties affect the reinforced resin viscosity whose flow is involved in the intimate contact evolution. Thus, a subtle and intricate coupling appears, and the process cannot be defined by ignoring it. In this paper, we analyze the effects of particle concentration and orientation on the process and processability. For this purpose, three main models are combined: (i) a multi-scale surface representation and its evolution, by using an appropriate numerical model, (ii) flow-induced orientation, and (iii) the impact of the orientation state on the homogenized thermal conductivity.

Glassy network epoxies have widespread applications as matrices for advanced composites As an alternative to thermal curing, electron beam (ebeam) processing has been demonstrated as a very powerful tool for achieving fast and efficient curing [1,2]. E-beam curing of epoxy based resins using suitable onium salts as initiators proceeds via a cationic mechanism. The final polymer network properties are highly dependent on processing conditions and curing kinetics. It was demonstrated that under certain processing conditions, heterogeneities can appear in the material, due to the agglomeration of initiator residue. Initially the initiator is miscible with the resin; however, reaction-induced phase separation occurs as the increasing molecular weight of the polymer reduces the solubility of the initiator.