Biaxial orientation of poly(vinyl chloride) compounds Part 2 –Structure–property relationships and their time dependency

This study emphasizes on closed-loop recycling of wood flour/poly (vinyl chloride) composites, since there is normally a considerable amount of material waste in wood plastic production lines. Composite materials were produced and subjected to four times reprocessing cycles under industrial conditions. Detailed analytical methods including bending strength, modulus of elasticity, impact strength, scanning electron microscopy, fiber length, water absorption, contact angle, Fourier transform infrared, and dynamic mechanical thermal analysis (DMTA) were conducted to evaluate the effects of recycling on the mentioned composites. Results demonstrated that the recycled composites, except for the four-time recycled ones, had lower bending strength, modulus of elasticity, and impact strength due to fiber-chain scission/fracture resulting from shear stress during reprocessing; however, impact strength remained almost unchanged after the first recycling cycle. Results also revealed that generally the reprocessed composites showed lower water absorption rates due to better fiber wetting and encapsulation. There was also a reduction in hemicellulose hydroxyl groups, rendering the recycled composites less hydrophilic. DMTA results showed an increase in mechanical loss factor (tan δ) for all the reprocessed composites showing a more viscous than elastic nature. The glass transition temperature of Rec4 composites increased due to polymer dehydrochlorination and the resulting cross-linking, which restricted the molecular mobility of the polymer chains.

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Structure-property relationships of PE/PP sandwiched films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126998 ◽

1987 ◽

Vol 45 ◽

pp. 454-455

Author(s):

J. Petermann ◽

G. Broza ◽

U. Rieck ◽

A. Jaballah ◽

A. Kawaguchi

Keyword(s):

Mechanical Tests ◽

Polymer Materials ◽

Ionic Crystals ◽

Structure Property ◽

Polymer Systems ◽

Structure Property Relationships ◽

Oriented Films ◽

Materials Used ◽

Polymer Laminates ◽

Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

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Approaches for TEM imaging of cavitation in toughened nylon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153737 ◽

1989 ◽

Vol 47 ◽

pp. 352-353

Author(s):

Barbara A. Wood

Keyword(s):

Morphological Characteristics ◽

Structure Property ◽

Polymer Systems ◽

Selective Staining ◽

Structure Property Relationships ◽

Rubber Toughened ◽

Shear Yield ◽

Controversial Topic ◽

Selection Of ◽

Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

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Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

10.26434/chemrxiv.12588965 ◽

2020 ◽

Author(s):

Alex Stafford ◽

Dowon Ahn ◽

Emily Raulerson ◽

Kun-You Chung ◽

Kaihong Sun ◽

...

Keyword(s):

Near Infrared ◽

Transient Absorption ◽

Reaction Times ◽

Infrared Light ◽

Structure Property ◽

Light Emitting ◽

Structure Property Relationships ◽

Nir Light ◽

Light Intensities ◽

Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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