The creation of highly oriented, co-extruded polypropylene (PP) tapes allows the production of recyclable ‘all-polypropylene’ composites, with a large temperature processing window (>30 °C) and a high volume fraction of highly oriented PP (>90%). These composites show little deviation of mechanical properties with compaction temperature. This paper introduces all-polypropylene composites and reports the tensile and compressive properties of unidirectional composites. These composites show good retention of tape properties despite the relatively high temperatures used in composite manufacture.

The mechanical properties of unidirectional all-polypropylene composites

Increasing concern for the environment has stimulated interest in the research and development of single polymer composite (SPC) materials. These materials are an emerging class of composite materials with mechanical properties comparable to heterogeneous composites. The SPCs are fully recyclable and have specific economic and environmental benefits. The small melting temperature difference between the fiber and the matrix poses a great challenge in the fabrication of SPCs. This article gives an overview of developments in SPCs relating to the materials and fabrication methods used.

Single polymer composites: a review

Analyzing and understanding the structure and morphology of crystalline polymers has been and remains to be a major challenge. Some of the issues have resisted analyses for decades. The present account illustrates how individual contributions help build a body of knowledge that must cover length scales ranging from submolecular features to morphology and correlates them with bulk properties. Emphasis is put on structures and morphologies as formed spontaneously. Possible extension of the research area to connected fields is illustrated with a development on supramolecular crystals.

50th Anniversary Perspective: Polymer Crystals and Crystallization: Personal Journeys in a Challenging Research Field

The current status of high-strength/high-modulus polyethylene fibres is reviewed with the emphasis on fundamental aspects of ultra-drawing and processability. The drawing mechanism as well as the temperature dependence of the drawability of UHMW-PE (ultra-high-molecular-weight polyethylene) will be discussed.

/pdf/chain-extended-polyethylene-4d1ogf28tm.pdf

Chain-Extended Polyethylene

A detailed comparison between molecular dynamics computer simulations and the experimental characterization of molecular motion through deuterium nuclear magnetic resonance (NMR) spectroscopic methods has been carried out for the crystalline phase of nylon 66 (polyhexamethyleneadipamide) at room temperature and just below the melting point. The computer simulations agree quantitatively with the experimental results at room temperature and qualitatively near the crystalline melting point. Both methods demonstrate that individual methylene groups within the crystals exhibit librational motion, which becomes very large in amplitude near the melting point, rather than undergoing discrete conformational jumps; furthermore, the hydrogen-bonded amides are relatively immobile at all temperatures below 230 degrees Celsius. The simulations are shown to be particularly useful for exaning the cooperativity of motion and for providing insight into structural-dynamical correlations. These aspects of the simulations are exemplified by the observation of concerted counterrotation of odd-numbered bonds within the methylene segments and the entropic stabilization of the crystal structure.

http://science.sciencemag.org/content/sci/247/4941/431.full.pdf

Molecular dynamics in ordered structures: computer simulation and experimental results for nylon 66 crystals.

https://pure.tue.nl/ws/files/1930382/619794.pdf

Rob Kirschbaum

Papers

Speciality products based on commodity polymers