Enno Klop

Enno Klop
Teijin Aramid · Research Institute, dept. Fiber and Polymer Physics

About

35
Publications
1,774
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917
Citations
Citations since 2016
2 Research Items
288 Citations
201620172018201920202021202201020304050
201620172018201920202021202201020304050
201620172018201920202021202201020304050
201620172018201920202021202201020304050

Publications

Publications (35)
Article
Aramid fibers are of practical interest due to their high tensile strength, high elastic modulus, low elongation at breakage, and thermomechanical stability. Here we combine high-resolution solid-state NMR and density functional theory (DFT) calculations to gain insight into the details of the molecular packing of p-phenylene terephthalamides (PPTA...
Article
The synthesis and structural characterization of various aromatic−aliphatic 15 polyamides are reported in this study. The polymers are obtained by solution polymerization of 16 p-phenylenediamine with various aliphatic diacid chlorides. The resulting polyamides are labeled 17 PA P-X, where X varies between 5 and 10 and corresponds to the number of...
Article
Full-text available
Recently, a Monte Carlo method has been presented which allows for the form-free retrieval of size distributions from isotropic scattering patterns, complete with uncertainty estimates linked to the data quality. Here, we present an adaptation to this method allowing for the fitting of anisotropic 2D scattering patterns. The model consists of a fin...
Article
Biobased polyamides synthesized from diaminoisoidide (DAII), 1,4-diaminobutane, and sebacic acid are investigated by FT-IR, 13C{1H} magic-angle spinning/cross-polarization (CP/MAS) NMR spectroscopy, and WAXD. Their molecular conformation and mobility undergo distinct changes as a function of temperature and diaminoisoidide content in the compositio...
Article
Full-text available
Aramid fibres are high-performance materials proposed in geotextiles for alkaline ground reinforcement. To study their durability in such environments, accelerated ageing has been carried out at pH 9 and at pH 11 for up to one and a half years. First, the lateral and longitudinal crystallite sizes have been determined before and after ageing under...
Article
Determining the effects of stress on the internal structure of high-performance fibres may provide insight into their structure–property relationships. The deformation of voids inside a poly( p -phenylene terephthalamide) (PPTA) fibre upon application of stress is one such effect which may be observed using in situ small-angle X-ray scattering. For...
Article
Novel, semicrystalline polyamides and co(polyamides) were synthesized from biobased sebacic acid (SA), 2,5-diamino-2,5-dideoxy-1,4;3,6-dianhydroiditol (diaminoisoidide, DAII) as well as from 1,4-diaminobutane (DAB), also known as putrescine in nature. Low molecular weight polyamides were obtained by melt polycondensation of the salts based on these...
Article
By mapping the small-angle X-ray scattering (SAXS) from a looped poly-(para-phenylene terephtalamide) (aramid, PPTA) filament using a synchrotron X-ray microbeam, we investigate the effects of axially compressive and tensile strain on internal fibrillar structures. Unique observations of oscillations in the highly anisotropic SAXS patterns indicate...
Article
Full-text available
After consideration of the applicability of classical methods, a novel analysis method for the characterization of fibre void structures is presented, capable of fitting the entire anisotropic two-dimensional scattering pattern to a model of perfectly aligned, polydisperse ellipsoids. It is tested for validity against the computed scattering patter...
Article
Full-text available
A series of PpPTA aramid fibres with various degree of lateral orientation ranging from their usual radial-oriented lateral texture to a full random lateral texture were prepared by employing a series of different coagulating media in the fibre spinning process. The resulting variation in lateral texture did not lead to differences in linear tensil...
Article
Full-text available
A novel route for the production of the rigid rod fiber poly-2,2'-(p-phenylene)-6,6'-bibenzoxazole (biPBO) was investigated. This fiber was prepared via its precursor polymer poly(3,3'-dihydroxybenzidine terephthalamide), abbreviated as DHBTA. The dissolution behavior of the precursor polymer was tested in various solvents and it was found that bas...
Article
Ab initio total energy calculations at the DFT-GGA level for PIPD are reported. Both the monoclinic crystal with a bi-directional hydrogen-bond network and the triclinic crystal with a sheet-like network are studied. It is concluded that the latter is the more plausible microstructure for the fibre based on the following: (i) After optimisation of...
Article
The development of the new high-modulus and high-strength fibre M5, made of poly{2,6-diimidazo[4,5-b:4′,5′-e]-pyridinylene-1,4(2,5-dihydroxy)phenylene} or PIPD, has resulted in an organic polymer fibre with exceptional fire protection properties when compared with PBO, Twaron, Kevlar and Nomex fibres. The PIPD as-spun fibre with a modulus of 150 GP...
Article
The smectic properties of four series of dimer liquid crystals containing cholesteryl and biphenylyl groups were investigated by polarization microscopy, DSC and X-ray diffraction. Compounds that contain the strongly dipolar cyanobiphenylyl group exhibit a smectic layer spacing that is about 1.7 times the length of the molecule. Three series of alk...
Article
Characteristic features of the molecular structure of polyethylene naphthalate (PEN) are the rigidity of the polymer chains and the occurrence of two trans conformations of the naphthalene ring, the so-called α- and β-conformations. The rigidity of the molecular chains permits production of PEN tyre yarns by a simple high-speed melt spinning proces...
Article
The new rigid-rod polymer fibre PIPD was studied using wide angle X-ray scattering. The crystal structure of as-spun PIPD fibre can be described as a two-dimensionally ordered crystal hydrate. Its equatorial X-ray diffraction pattern was indexed to a non-primitive rectangular unit cell with parameters 16.85, 3.38 Å, containing two polymer chains. H...
Article
The polymer poly{2,6-diimidazo[4,5-b:4′,5′-e]pyridinylene-1,4(2,5-dihydroxy)phenylene} (PIPD) is spun from a liquid crystalline solution in polyphosphoric acid. The as-spun fibre is a crystal hydrate, which transforms into a bidirectional hydrogen-bonded structure during heat treatment. This transition results in an increase in crystalline modulus...
Article
Differential scanning calorimetry and high temperature x-ray diffraction were used to study the perfectly alternating copolymer of ethene and carbon monoxide (polyketone; POKC2). It was found that oriented POK-C2 fibers show a crystalline phase transition at a temperature between 110–125°C with a 10% change in crystalline density. At this temperatu...
Article
The perfectly alternating ethylene carbon monoxide copolymer (polyketone; POK) has been studied by means of 1H nuclear magnetic resonance and thermal analysis, and the crystal structure, determined by wide angle x-ray scattering methods, is presented. The crystal structure of this polymer in well-oriented fibers (POK-α) is as follows: Space group P...
Article
The procedure adopted by Heinerman [Acta Cryst. (1977). A33, 100-106] to incorporate structural information in phase determination is combined with that of Giacovazzo [Acta Cryst. (1983). A39, 685-692]. The resulting joint probability distribution of three structure factors is a generalization of the corresponding distributions of the previous auth...
Article
The two-step procedure for estimating triplet invariants from two-wavelength data [Klop, Krabbendam & Kroon (1989). Acta Cryst. A45, 203-208] is applied to artificial data from the protein ferredoxin. Two different probability distributions for the estimation of triplet invariants are compared. The possibility of estimating triplet phase invariants...
Article
A two-step procedure is presented for the estimation of triplet invariants from multi-wavelength data. In the first step wavelength-independent structure-factor magnitudes of both the total structure and the light-atom substructure, together with associated structure-factor phase differences, are calculated explicitly via a modified Singh & Ramases...
Article
The joint probability distribution of six structure factors for a pair of isomorphous structures [Hauptman (1982). Acta Cryst. A38, 289-294] is used for probability calculations in which doublet invariant phase information (i.e. phase-difference information) is employed as conditional information together with intensity data. This information is ob...
Article
The 2/1 reactions of the N2S2 ligand system (R,S)-1,2-(5-R-thio-2-CH=N)2-c-Hx (R = H (1a), Me (1b); thio = thiophene, c-Hx = cyclohexane) with M = Ag(I), Cu(I) yielded stable mononuclear [M(N2S2)2](O3SCF3) complexes. An X-ray crystallographic study of [Ag(1b)2](O3SCF3) defined its molecular structure: triclinic, space group P1, a = 9.900 (4) Å, b =...
Article
In designing model complexes for the activities sites in copper proteins it is important to know the influence of the different hetero-atoms and conformational changes of the carbon skeleton on the chemical and physical properties of the metal centre.We have investigated the structure properties of copper(I) and silver(I) complexes with potentially...
Article
The azaphospholes P=NN(Me)C(Me)=N (L{N}) and P=C(H)C(Me)=NN(Me)(L{C}) have been used to synthesize the air-sensitive Pt}0{ complexes [Pt(PPh{3}){2}L{2}] and [Pt(PPhP{3}){3}L] (L = L{N}, L{C}), which are stable towards dissociation in solution at -40}o{C. One representative [Pt(PPh{3}){3}L{N}] (I) has been the subject of a single-crystal X-ray diffr...

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