Polymer composites have proved to be an effective measure of material innovation, which combine the advantages of inorganic fillers (e.g., particulates, fibers, etc.) and organic polymer matrices. This is especially true for modern polymer engineering, where less and less brand new synthetic polymers are transformed from laboratory scale preparation to industrialized production.

“Advanced Industrial and Engineering Polymer Research” is an international academic journal primarily targeted at both industrial and academic researchers on all aspects of polymer studies and practical applications, in hopes of bridging the gap between these groups. Polymer composites are chosen as the main theme of the inaugural issue, which conforms to the vision of the editorial board, i.e. promoting positive hybrid effects of diverse knowledges or materials.

Here, the papers written by worldwide eminent scientists from different angles are collected. In spite of the limited space, a broader spectrum of interesting topics is covered to the best of the editors' ability. The readers may figure out the state-of-the-art and developing trend in this area accordingly.

In general, properties of matrix polymers greatly affect processability and performance of composites. Any change in matrix species would result in a new family of polymeric composites. The review article by Karger-Kocsis and Sibikin systematically discusses synthesis, modification, and manufacturing of lactam-based polymers and their composites. The high performance composite materials and the related processing techniques are promising for versatile applications.

Composites interface in another important subject for academia and industry. The work by Mäder and her co-workers compares the influences of geometrical and physical factors as well as dada analysis on interfacial properties of fiber reinforced epoxy and nylon-6,6, respectively. They successfully find out the most reliable method of quantification of interfacial interaction, which lays the foundation for precise characterization of future investigation. In the case of thermoplastic composites, interfacial crystallization, i.e. transcrystallization, is closely related to their mechanical strength. It in turn becomes a useful parameter for tuning property. The group of Goda reports the relationship between transcrystalline layer in injection-molded ramie/polyamide and tensile strength. The former appears to more prominently enhance the composite as compared to heat treatment. Meanwhile, McNally et al. study the issue in terms of isothermal and non-isothermal crystallization kinetics. Their results about multi-walled carbon nanotubes filled polypropylene reveal the crystal growth behavior, which may be directly correlated to optimization of processing.

With respect to polymer nanocomposites, which have attracted intensive interests since the invention of clay/nylon 6 hybrid in Toyota in 1985, the over thirty-year researches so far indicate inorganic nanoscale building blocks are hard to be dispersed in an organic polymer matrix using existing techniques. In this context, Fakirov proposes the concept of “converting instead of adding”. Two types of polymer nanocomposites, nanofibrillar polymer-polymer and nanofibrillar single polymer composites, are described in his review article. It shows good examples of thinking differently.

Besides mechanical properties, functional properties is also a main concern of polymer composites. Friedrich comprehensively reviews traditional applications of polymeric tribo-component, and recent achievements in imparting additional functionalities (e.g., electroconductivity and self-healability) to polymer composites for tribological applications. Moreover, additive manufacturing methods for friction and wear loaded polymer parts, and the composition of polymer composites under friction at cryogenic temperature conditions are included. On the other hand, Chung provides a general overview of thermoelectric polymer composites, which serve as candidates for energy materials. Her focus is laid on composition, structure and method of preparation of nonstructural and structural composites, which are critical for conversion of thermal energy to electrical energy.

In the paper by Sun et al., strategies for improving dielectric properties of epoxy composites are explored. By taking advantage of various fillers (i.e. carbon black, carbon black@TiO₂ core-shell particles and CB-SiO₂ hybrid particles), dielectric properties of the epoxy composites are improved due to interfacial polarization or micro-capacitor effect. Interfacial polarization loss, dipolar relaxation loss and conduction loss are found to account for the dielectric loss in the composites.

Last but not least, it is worth noting that polymer composites are advancing towards intelligent materials for the next-generation industry. The group of Michaud summarizes the current applications of shape memory alloy wires in high performance fiber reinforced polymer composites. They indicate that the composites can be coupled with improved damping response, impact resistance, crack closure capability and shape morphing.

The progress in polymer composites is bringing about changes day after day. This issue could only present a timely report of a few developments in the field. It is believed that many more interesting results will be reported in the near future.

To conclude, may we take the opportunity to express our sincere gratitude to all the authors for their highly qualified contribution to this inaugural issue and to all the colleagues who agreed to serve as reviewers for their help and efforts in ensuring a strong collection of papers.

Special thanks are due to Mr. Zhimin Yuan, chairman of the board of Kingfa Sci. & Tech., for his initial proposal of the journal and continuous support.

Many different polymers and polymer composites are used for engineering applications in which friction and wear are critical issues. This article briefs (a) the importance of polymer tribology in general, (b) the special design principles of polymer composites for low friction and wear under sliding against smooth metallic counterparts, and (c) synergistic effects of nano-particles and traditional fillers and fibers for an optimal tribological performance. Based on these fundamental aspects, the article reviews traditional applications of polymeric tribo-components in mechanical and automotive engineering, including slide elements in textile machines, filament wound bushings for harsh environments, cages of high-precision ball bearings in dental turbines, and hybrid bushings in Diesel fuel injection pumps. A following chapter on special developments of tribo-components outlines (a) ways to achieve electrical conductivity of polymer bearings, (b) the enhancement of self-lubrication and self-healing potential by the incorporation of micro-capsules into the polymer matrix, (c) modern additive manufacturing methods for friction and wear loaded polymer parts, (d) the application and properties of high temperature polymer coatings, and (e) the composition and use of polymer composites under friction at cryogenic temperature conditions.

The review deals with the reasons for the drastic difference between the theoretically derived expectations regarding the mechanical properties of polymer nanocomposites and the experimentally obtained results. It is assumed that the most probable reason is the fact that we hardly deal with true nanocomposites because in the composites prepared via blending of polymer matrix with the reinforcing nano-size material the reinforcing elements are not the single nanoparticles but their aggregates with sizes in the micrometer range. This situation is due to the fact that currently there are not effective techniques for proper dispersion of nanomaterials into polymer matrix. The solution suggested is in avoiding the dispersion step in the composite preparation as the “concept of converting instead of adding” does. Two examples of true polymer nanocomposites – the nanofibrillar polymer–polymer and the nanofibrillar single polymer composites – are described.

This paper gives an overview of lactam-based polymers and related composites produced via anionic ring opening polymerization (AROP). Recent and past achievements, grouped into academic and industrial research works, and covering also the chemistry (initiator and activator systems) and modification possibilities of in situ polymerized ε-caprolactam (CL) and ω-lauryllactam (LL) are presented and discussed. Special emphasis was put on the industrial applications of AROP of CL and LL resulting in polyamide-6 (PA6) and PA12, respectively. The results achieved are surveyed and highlighted according to the preparation and manufacturing techniques. Based on this state-of-art review, development trends for the future were concluded and their possible drivers suggested.

This paper reviews thermoelectric polymer-matrix composites, including nonstructural and structural materials. The structural materials are continuous fiber composites; the nonstructural materials are discontinuously reinforced composites and polymer-polymer composites. A thermoelectric structural composite uses the reinforcing continuous fibers to enhance the electrical conductivity. The directionality of the continuous fibers allows tailoring of the thermoelectric behavior in various directions, particularly the through-thickness direction and the fiber direction. The use of laminae with dissimilar fibers (with opposite signs of the thermoelectric power) that are in different directions provides an array of unmodified and ordinarily made interlaminar interfaces, which serve as an array of thermocouple junctions that are based on the fiber-dominated thermoelectric behavior in the fiber direction of each lamina. By modification through positioning fillers at the interlaminar interface, the filler-dominated through-thickness thermoelectric behavior can be tailored. By using dissimilar fillers at the interlaminar interface, dissimilar composites that exhibit opposite signs of the thermoelectric power are obtained. Nonstructural thermoelectric composites exhibit a large range of ZT values, depending on the composition, structure and method of preparation.

This article reviews the current state-of-the-art in the applications of shape memory alloy (SMA) wires into high performance fibre reinforced polymer composite materials (FRPs). SMAs have been investigated to date to address four main areas of properties improvement: (i) damping and vibrational response, where SMAs are integrated into composites either in the plane of the neutral axis, or as transverse stitches; (ii) impact, where SMAs are integrated in the neutral axis or as stitches; (iii) crack closure, where SMAs are integrated transverse to the crack, as stitches and (iv) shape morphing, where SMAs are integrated in plane into the composite, but in the non-neutral axis. The critical parameters for successful integration of SMAs to FRPs are highlighted, mostly from a composite processing angle. Finally, this review evaluates some hurdles remaining in the implementation of SMAs to FRPs to create smart and efficient composite structures without compromising their processing route, structural properties, weight and cost.