A Novel Impact Modifier for Nylon 6

A new carboxylated styrene‐butadiene rubber (CSBR) in ultrafine powder form was used to modify the properties of nylon 6. The nylon 6/CSBR blends possessed higher toughness than nylon 6/maleic anhydride‐grafted polyethylene‐octene elastomer (POE‐g‐MAH) system. TEM micrographs revealed the fine dispersion of CSBR particles with a diameter of 150 nm. The effective toughening of nylon 6 with CSBR was attributed to the good interface, fine dispersion, and shear yielding.

TEM photograph of undeformed Nylon 6/CSBR (80/20) blend (×40 000).     

Photoinduced Polymerization in the Wall of Hollow Capsules

Summary: Novel light‐sensitive hollow capsules were fabricated from the small molecule 3‐sulfopropylacrylate potassium (SPA) and poly(allylamine hydrochloride) (PAH). With UV irradiation, SPA could be photopolymerized in the wall of hollow capsules. After photopolymerization the capsule size and surfaces showed pronounced differences. The capsules became much more rigid as indicated by an increase in the modulus of more than a factor of 5.

CLSM image of SPA/PAH hollow capsule emission at 554 nm, from rhodamine B after photopolymerization.     

Properties of Polyimide/Silica Nanohybrids from Silicic Acid Oligomer

Summary: A new method to synthesize polyimide (PI)/silica nanohybrids has been presented. It uses silicic acid oligomer as the silica precursor, which was obtained by extracting with tetrahydrofuran (THF) from PH‐adjusted water glass. The films of PI/silica nanohybrids remained transparent even at high silica content due to the formation of nanometer‐scaled SiO₂ particles at the addition of γ‐aminopropyltriethoxysilane (APTES). In comparison with pure PI, PI/silica hybrids showed improved thermal stability and mechanical properties, and lower linear coefficients of thermal expansion (CTEs). The glass transition temperatures of the hybrids were increased with increasing content of silica or APTES as a result of the increasing limitation to the movements of the PI backbone.

SEM photograph of PI 20/4.     

Novel Phenol‐Formaldehyde Resins, 2. Resols Prepared Using Reactive Solvents

New results on the method of preparation of phenol‐formaldehyde resins from phenol and multihydroxymethyl derivatives of some ketones are presented. The latter, known as the reactive solvents of melamine, were prepared by reacting acetone and methyl ethyl ketone with excess of formaldehyde. A novel group of resins of resol type has been obtained. The structure of products is discussed and compared to that of classical resols. The fragments of ketones have been found incorporated into the structure of resins.

Temperature dependence of viscosity of a classical resol and of the resols modified with reactive solvents.     

The Reinforcement of Elastomeric Networks by Fillers

Summary: The mechanisms involved in rubber reinforcement are discussed. A better molecular understanding of these mechanisms can be obtained by combining characterization of the mechanical behavior with an analysis of the chain segmental orientation accompanying deformation. While the strain dependence of the stress is the most common quantity used to assess the effect of filler addition, experimental determination of segmental orientation can be used to quantify the interfacial interactions between the elastomeric matrix and the mineral inclusions.

SEM micrograph of natural rubber containing 10 wt.‐% of organomodified clay.     

Organocatalytic Enantioselective Alkylation of Pyrazol‐3‐ones with Isatin‐Derived Ketimines: Stereocontrolled Construction of Vicinal Tetrasubstituted Stereocenters

A quinine‐derived thiourea catalysed the enantioselective addition of 4‐substituted pyrazolones to isatin‐derived ketimines, providing a variety of aminooxindole‐pyrazolone adducts containing congested vicinal tetrasubstituted stereocentres with excellent outcomes (up to 98% yield, >20:1 dr and 98% ee).

     

Injection Moulding: Evaluation of Appropriate Melt Injection Points for the Gas Injection Technique

In gas assisted injection moulding the melt front advancement has a considerable effect on the gas penetration. The evaluation of an appropriate melt filling is an important step to avoid instabilities in the process sequence. Taking a sample moulded part a procedure is presented that enables the part designer to evaluate required melt and gas injection points according to the gas injection technique. Using finite element simulations, different calculations for the melt front advancement lead to the correct gate location.

Presentation of different degrees of filling for the optimised article geometry.     

Extrusion Monitoring of Polymer Melts Using a High‐Temperature Surface‐NMR Probe

Summary: Extrusion is one of the major ways of polymer processing, and extrusion monitoring is important to control or improve the extrusion process and the product quality. Especially methods for in‐line monitoring are desired because those enable the fastest possible response and a localization of chemical reactions in reactive processing. Methods of optical and acoustic spectroscopy have successfully been implemented so far. NMR provides a wealth of information. Surface NMR mostly gives access to molecular mobility via relaxation times. These can be correlated to temperature, composition and homogeneity which are substantial indicators for the product quality. NMR is a non‐destructive method, which does not require direct contact with the sample and it is not restricted to optical transparent materials and is therefore suitable for extrusion monitoring. The problem for the adaptation is the hostile environment in and in front of an extruder for polymer melts. Here, a NMR surface probe is presented sustaining this environment in front of an extruder. First measurements with this device are shown.

High‐temperature surface‐NMR probe.     

Preparation and Characterization of Hyperbranched Polymer/Silica Hybrid Nanocoatings by Dual‐Curing Process

Summary: Organic‐inorganic nanocomposite hybrid coatings were prepared through a dual‐cure process involving cationic photopolymerization of a hyperbranched epoxy functionalized resin and subsequent condensation of an alkoxysilane inorganic precursor. All the formulations investigated gave rise to photocured films characterized by high gel content values. An increase in glass transition temperature and an increase in storage modulus above T_g in the rubbery plateau is observed with increasing TEOS content in the photocurable formulation. The important role of GPTS on reducing the inorganic domain size and avoiding macroscopic phase separation was demonstrated by TEM analyses.

TEM obtained for one of the cured films in the presence of GPTS.     

Organolithium route to poly(arylsilane)s

Various poly(arylsilane)s The poly(carbosilane)s prepared in this way are of higher molecular weight than when prepared by the Wurtz-type condensation route previously reported. TG shows 40–50% overll weight loss attained at 500–600°C.     

Exertion of Inhibiting Effect by Aluminosilicate Layers on Swelling of Solution Blended EVA/Clay Nanocomposite

Summary: Ethylene vinyl acetate (EVA) copolymer/dodecyl ammonium ion intercalated montmorillonite (12Me‐MMT) nanocomposites were swelled in xylene under atmospheric condition. Swelling index of these nanocomposites decreased with filler loading indicating that the solvent uptake of these nanocomposites was inversely related to the filler contents. The volume fractions of nanocomposites showed an increasing trend with filler concentration because of unswelling effect exerted by aluminosilicate layers. The cross‐link density was determined using the Flory‐Rehner equation and it was observed that the cross‐link density of these nanocomposites also showed an increasing trend with increasing filler loading. Free energy change (ΔG_mix) and the change in entropy (ΔS_mix) on swelling of EVA/12Me‐MMT nanocomposites in xylene were calculated and these values reaffirmed that the interaction between polymer chains and silicate layers was very strong which induced remarkable inhibiting ability on EVA matrix when swelled in xylene.

TEM photograph of EVA/12Me‐MMT nanocomposite containing 8 wt.‐% 12Me‐MMT.     

Inhomogeneity Effects in Vapor Phase Polymerized PEDOT: A Tool to Influence Conductivity

Low‐MW urethanes were investigated to control domain formation as well as inhibiting cleavage reactions during vapor phase polymerization of PEDOT. A diurethanediol (DUDO) was identified as a highly efficient mediator for the process, resulting in PEDOT films exceeding conductivities of 1 000 S · cm^?1. All the urethanes investigated had the desired inhibiting effect on the polymerization, but all apart from DUDO also introduced unwanted domain formation on the micrometer scale. The addition of PEG generally improved conductivity by suppressing the domain formation and, with an optimized combination of DUDO and PEG, conductivities over 1 200 S · cm^?1 were achieved.

     

Synthesis and Characterization of Hyperbranched Poly(β‐ketoester) by the Michael Addition

Summary: A novel hyperbranched poly(β‐ketoester) was synthesized from 2‐(acetoacetoxy)ethyl acrylate by the Michael addition in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as catalyst. ¹H NMR integration experiments revealed that the degree of branching in the poly(β‐ketoester) was remarkably high at a level of 82.9%. The number‐average molecular weight of the polymer was between 2 100 and 12 000 and increased with reaction temperature and conversion.

Synthesis of hyperbranched polymer by Michael addition of AAEA.     

Reaction of azo derivatives of acetoacetanilide with aliphatic amines

Azoacetoacetanilides condense with primary aliphatic amines to give azoaminocrotoanilides (I). Comparison of the infra-red and nuclear magnetic resonance spectra with those of model compounds leads to the proposal of formulae of type (VI) as a refinement of formula (I).      

The Anisotropy of Fibrillar Silicate/Rubber Nanocomposites

Summary: Fibrillar silicate (FS)/rubber nanocomposites were successfully prepared by directly mixing modified FS with rubber matrix. It is found that FS could be separated into nano‐fibrils with diameters less than 100 nm by the shear forces during mixing. The stress‐strain characteristics of these composites are similar to those for short micro‐fiber/rubber composites (SFRC). Nevertheless, these FS/rubber composites have some outstanding advantages over the conventional SFRC, even though the reinforcing effect of FS is restricted due to its small shape aspect ratio. More importantly, the differences in mechanical properties of the composites in the two different directions show that SBR/FS and NBR/FS composites both exhibit obvious anisotropy, which strongly depends on the preparation process, FS concentration, and rubber matrix. These factors were thoroughly investigated in this paper, and it can be concluded that the anisotropy of the composites was due to the orientation of nano‐fibrils.

     

An NMR‐MOUSE® for Analysis of Thin Objects

A special unilateral NMR sensor has been designed for investigations of thin samples with a thickness of less than 1 mm and of surface effects of polymers. For use with the bar‐magnet NMR‐MOUSE®, the so‐called “crazy coil” is introduced with a low penetration depth. It is a flat meander coil etched on a printed circuit board with wiggles in the conductors. The design of the new coil and FEM simulations of the B ₁ field are presented. Different applications are discussed by means of illustrative examples. They are the detection of surface damage in rubber samples, the swelling and drying of a latex membrane exposed to cyclohexane vapor mimicking a chemical sensor, and the drying of a thin sprayed adhesive layer.

Bar‐magnet NMR‐MOUSE® with crazy coil.     

Simulation of Nylon 6 Polymerization in an Industrial Two‐Step VK Tubular Reactor

A commonly used nylon 6 two‐step VK tubular reactor is simulated in this work. To verify the reliability of the model, careful comparison with results obtained on different continuous plants is made. The effect of various conditions and parameters, e.g. feed composition, temperature, pressure, etc. on the product properties such as caprolactam conversion, degree of polymerization (DP), dimer, integral heat and their distribution index is studied. It is observed that the caprolactam conversion and DP of the product may be affected by various conditions in the first stage and the temperature profile at the top of the second stage, but they finally reach the equilibrium values if the residence time is long enough. The most effective way to increase DP of the product is to increase the vacuum at the top of the second stage.

CPL conversion and DP profile for pressure of tube 2: 0.032, 0.037, 0.042 mPa; other parameters as given for example A of Table 5 .     

Thermoplastic Polyurethane Nanocomposites Produced via Impregnation of Long Carbon Nanotube Forests

TPU was infiltrated into vertically aligned, 3.5 mm‐long MWNT forests to produce continuously reinforced anisotropic nanocomposites, and thermomechanical and electrical testing has revealed multifunctionality which shows promise for numerous applications. A 1000% increase in the storage modulus at 70 °C was observed as compared to the neat TPU, and these continuously aligned composites showed electrical conductivity two orders‐of‐magnitude greater (≈1.5 S · cm^?1) than randomly aligned composites prepared using CNTs from these forests. The heightened improvement for the continuously reinforced composite appears to be owed to the extremely high aspect ratio of these CNTs and the interconnected network which remains after infiltration.