The production of foams based on PVC and difunctional isocyanates is equipment intensive and a ti... more The production of foams based on PVC and difunctional isocyanates is equipment intensive and a time consuming process. The components are mixed together at room temperature to form a plastisol. This plastisol is heated in a mould under high pressure to decompose the blowing agent and produce a homogeneous material. The 'embryo' is cooled and removed from the mould. The embryo is reheated to a temperature above the T g of the mass and is allowed to expand. The foam produced is closed celled but at this stage still soft. Water is required to initiate the curing process for the isocyanate, i.e. it is required that water diffuse through the foam structure to complete the process. This may be performed in a chamber at 60°C and 100% humidity over an extended period of time. Because of the nature of diffusion this stage sets limitations on the maximum density and thickness of commercially viable products. This paper presents a method for the generation of water within the polymer matrix during the latter stages of production hence reducing or eliminating the need for the humidity treatments (1) . Water is freed by the acid catalysed dehydration of alcohols. The chemistry is described in detail and experimental evidence is presented to support the postulated reactions. The effects of alcohol structure and concentration on mechanical properties immediately after expansion are presented.
Linear isotactic metallocene based polypropylene (M w ¼ 125,000 g/mol, M n ¼ 61,000 g/mol) was li... more Linear isotactic metallocene based polypropylene (M w ¼ 125,000 g/mol, M n ¼ 61,000 g/mol) was lightly crosslinked by small amounts of 1,3-benzenedisulfonyl azide to form long chain branches (LCB). Crosslinking was carried out by reactive extrusion at 2008C in a small scale extruder. At the processing temperature, the two azide groups decompose to nitrenes that work as crosslinkers for PP. The crosslinking reaction occurs primarily by insertion of singlet nitrenes into CÀ ÀH bonds. 1,3-benzenedisulfonyl azide concentrations of, respectively, 518, 806, 1029, and 2038 ppm were used. SEC revealed formation of a high molecular weight LCB fraction. No degra-dation was observed by SEC. The introduction of LCB gave rise to rheological behavior typical of LCB as increased zero shear viscosity, accompanied by increased shear thinning, increased flow activation energy and a phase angle plateau. However, the rheological impact and crosslinking efficiency observed were limited compared to earlier studies on PE. Possible reasons for this are discussed.
International Journal of Adhesion and Adhesives, 2002
ABSTRACT Before testing the ability of different pre-treatments to promote adhesion, a detailed d... more ABSTRACT Before testing the ability of different pre-treatments to promote adhesion, a detailed description of the rheological and mechanical properties of the adhesive is needed. Change of the adhesive properties (due to incomplete curing) can indeed affect the results of the adhesion tests and screen out the effect of the pre-treatment. A two component room temperature curing adhesive paste (Araldite 2014) has been selected. The characterization of the adhesive properties was conducted with respect to the curing temperature and to the elapsed time between the gluing and the testing. It has been shown that any curing temperature increase leads to a more complete curing after a short period of time when the conversion factor reaches a plateau-like regime. In that regime the reaction rate becomes diffusion controlled and the reaction is drastically slowed down. Measurements of the mechanical properties of adhesive samples showed that 28 days are needed at room temperature to complete the curing process (only 4h at 64°C) and that the properties of the adhesive during that period of time changed drastically. Ageing test (40°C in water vapour) has been conducted on adhesive samples and the adhesives properties recorded over a period of 36 days. It has been shown that the absorbed water works as a plasticizer leading to a softening of the adhesive. The E-modulus and the stress at break are lowered while the deformation at break and the plastic contribution to the total deformation are increased.
... from the polymeric coupling agent with highest molecular weight. Nygård and Redford [10] exte... more ... from the polymeric coupling agent with highest molecular weight. Nygård and Redford [10] extended this principle to the coupling prob-lem for glass fi bre and polypropylene. The bonding between the fi bre surface and the ...
ABSTRACT Bicyclohexyl, (C6H11)2(BCH), is a simple hydrocarbon and is the backbone of a group of c... more ABSTRACT Bicyclohexyl, (C6H11)2(BCH), is a simple hydrocarbon and is the backbone of a group of compounds that form nematic (and sometimes smectic) liquid crystals. The infrared (IR) spectra of BCH, studied some years ago, have been re-investigated. Low-temperature, and also high-pressure spectra, at room temperature, of the amorphous phase and of three crystalline phases were obtained. Raman spectra of the liquid and of the crystalline solids were also recorded. Bicyclohexyl has a number of phase transitions. They are reversible in terms of temperature and pressure variations, and they were carefully investigated by differential scanning calorimetry (DSC) and by the variable-temperature X-ray powder technique. In the low-temperature and also in the high-pressure crystals, BCH existed in three phases: in phase 1 (274–277 K) all conformers were present; in phase 2 (256.5–274 K) only the equatorial–equatorial anti conformer and in phase 3 (below 256.5 K) the equatorial–equatorial gauche conformer was present. An additional phase transition was observed at 266.5 K by DSC and X-ray methods, but no noticeable changes were observed in the spectra. A single crystal of the high-pressure phase 1 was investigated by polarized radiation, and the order parameters for various bands were determined in the IR region. From these data it is argued that phase 1 could be a smectic liquid crystal rather than a plastic crystalline phase.
ABSTRACT —This paper presents an interphase engineering technique suitable for grafting silane-mo... more ABSTRACT —This paper presents an interphase engineering technique suitable for grafting silane-modified polymers onto glass fibres to be used in composites with enhanced impact tolerance. The silane-modified polymers include ethylene polymers grafted with γ-methacryloxypropyltrimethoxysilane (MPS) and a copolymer of butyl acrylate (BuA) and MPS. The grafting of functionalized interphase materials onto glass fibres is performed in solution. By changing the concentrations of the solutions, different amounts of polymer can be deposited on the fibres. Water crosslinking of the polymer gives the possibility of producing stabilised interfacial polymer coatings over a range of thicknesses. It is concluded that acidic conditions (1) promote the grafting of silane-modified polymers on glass fibres and (2) for a given reaction time, increase the amount of crosslinked polymer in the interphase, i.e. yield more stable interphases. It is also likely that preserving acidic conditions at the fibre/polymer interface is important for maintaining bonding across the interface. It is shown that polystyrene/glass-fibre composites having SEBS at the interface are promising candidates for high-impact-tolerance composites.
Mosaic Solutions AS is developing a novel concept for conductive adhesives for use in electrical ... more Mosaic Solutions AS is developing a novel concept for conductive adhesives for use in electrical interconnection of solar modules. The goal is to provide an alternative to the current soldering process in module manufacturing, enabling lower process temperatures and reducing the amount of toxic elements, e.g. lead. The conductive adhesive is based on replacing solid silver flakes by polymer particles coated with a thin layer of silver. The main advantage of this concept, compared to conventional conductive adhesives, is a typical ten-fold reduction in silver consumption. We have investigated the electrical properties of conductive adhesives based on silver-coated polymer particles, and demonstrated the use of the conductive adhesive concept in module manufacturing. The results are promising, showing that the electrical conductivity is more than sufficient for use in solar modules, and that our conductive adhesive concept represents a promising and realistic alternative to soldering.
La presente invention concerne un vernis/vernis-laque ou un revetement de gel a base organique, d... more La presente invention concerne un vernis/vernis-laque ou un revetement de gel a base organique, de preference transparent et brillant capable de former des revetements presentant une resistance elevee a l'usure, ainsi que son procede de production. Ledit vernis/vernis-laque ou revetement de gel comporte une quantite controlee de particules de polymere inorganique presentant une taille sensiblement comprise entre 1 et 100 nm, les particules etant capables de constituer un reseau tridimensionnel independant du reseau organique du vernis-laque ou pouvant avoir des liaisons avec ledit reseau. De maniere caracteristique, les particules de polymere consiste en un produit reactionnel obtenu par des reactions d'hydrolyse et de condensation de composes de monomeres choisis parmi les groupes suivants: i) M(OR)n, ou ii) R'-M(OR)n, ou M est un ion metallique, et R est un groupe organique choisi parmi les groupes alkyle, alcenyle, aryle ou des combinaisons de tels groupes comprenant ...
The production of foams based on PVC and difunctional isocyanates is equipment intensive and a ti... more The production of foams based on PVC and difunctional isocyanates is equipment intensive and a time consuming process. The components are mixed together at room temperature to form a plastisol. This plastisol is heated in a mould under high pressure to decompose the blowing agent and produce a homogeneous material. The 'embryo' is cooled and removed from the mould. The embryo is reheated to a temperature above the T g of the mass and is allowed to expand. The foam produced is closed celled but at this stage still soft. Water is required to initiate the curing process for the isocyanate, i.e. it is required that water diffuse through the foam structure to complete the process. This may be performed in a chamber at 60°C and 100% humidity over an extended period of time. Because of the nature of diffusion this stage sets limitations on the maximum density and thickness of commercially viable products. This paper presents a method for the generation of water within the polymer matrix during the latter stages of production hence reducing or eliminating the need for the humidity treatments (1) . Water is freed by the acid catalysed dehydration of alcohols. The chemistry is described in detail and experimental evidence is presented to support the postulated reactions. The effects of alcohol structure and concentration on mechanical properties immediately after expansion are presented.
Linear isotactic metallocene based polypropylene (M w ¼ 125,000 g/mol, M n ¼ 61,000 g/mol) was li... more Linear isotactic metallocene based polypropylene (M w ¼ 125,000 g/mol, M n ¼ 61,000 g/mol) was lightly crosslinked by small amounts of 1,3-benzenedisulfonyl azide to form long chain branches (LCB). Crosslinking was carried out by reactive extrusion at 2008C in a small scale extruder. At the processing temperature, the two azide groups decompose to nitrenes that work as crosslinkers for PP. The crosslinking reaction occurs primarily by insertion of singlet nitrenes into CÀ ÀH bonds. 1,3-benzenedisulfonyl azide concentrations of, respectively, 518, 806, 1029, and 2038 ppm were used. SEC revealed formation of a high molecular weight LCB fraction. No degra-dation was observed by SEC. The introduction of LCB gave rise to rheological behavior typical of LCB as increased zero shear viscosity, accompanied by increased shear thinning, increased flow activation energy and a phase angle plateau. However, the rheological impact and crosslinking efficiency observed were limited compared to earlier studies on PE. Possible reasons for this are discussed.
International Journal of Adhesion and Adhesives, 2002
ABSTRACT Before testing the ability of different pre-treatments to promote adhesion, a detailed d... more ABSTRACT Before testing the ability of different pre-treatments to promote adhesion, a detailed description of the rheological and mechanical properties of the adhesive is needed. Change of the adhesive properties (due to incomplete curing) can indeed affect the results of the adhesion tests and screen out the effect of the pre-treatment. A two component room temperature curing adhesive paste (Araldite 2014) has been selected. The characterization of the adhesive properties was conducted with respect to the curing temperature and to the elapsed time between the gluing and the testing. It has been shown that any curing temperature increase leads to a more complete curing after a short period of time when the conversion factor reaches a plateau-like regime. In that regime the reaction rate becomes diffusion controlled and the reaction is drastically slowed down. Measurements of the mechanical properties of adhesive samples showed that 28 days are needed at room temperature to complete the curing process (only 4h at 64°C) and that the properties of the adhesive during that period of time changed drastically. Ageing test (40°C in water vapour) has been conducted on adhesive samples and the adhesives properties recorded over a period of 36 days. It has been shown that the absorbed water works as a plasticizer leading to a softening of the adhesive. The E-modulus and the stress at break are lowered while the deformation at break and the plastic contribution to the total deformation are increased.
... from the polymeric coupling agent with highest molecular weight. Nygård and Redford [10] exte... more ... from the polymeric coupling agent with highest molecular weight. Nygård and Redford [10] extended this principle to the coupling prob-lem for glass fi bre and polypropylene. The bonding between the fi bre surface and the ...
ABSTRACT Bicyclohexyl, (C6H11)2(BCH), is a simple hydrocarbon and is the backbone of a group of c... more ABSTRACT Bicyclohexyl, (C6H11)2(BCH), is a simple hydrocarbon and is the backbone of a group of compounds that form nematic (and sometimes smectic) liquid crystals. The infrared (IR) spectra of BCH, studied some years ago, have been re-investigated. Low-temperature, and also high-pressure spectra, at room temperature, of the amorphous phase and of three crystalline phases were obtained. Raman spectra of the liquid and of the crystalline solids were also recorded. Bicyclohexyl has a number of phase transitions. They are reversible in terms of temperature and pressure variations, and they were carefully investigated by differential scanning calorimetry (DSC) and by the variable-temperature X-ray powder technique. In the low-temperature and also in the high-pressure crystals, BCH existed in three phases: in phase 1 (274–277 K) all conformers were present; in phase 2 (256.5–274 K) only the equatorial–equatorial anti conformer and in phase 3 (below 256.5 K) the equatorial–equatorial gauche conformer was present. An additional phase transition was observed at 266.5 K by DSC and X-ray methods, but no noticeable changes were observed in the spectra. A single crystal of the high-pressure phase 1 was investigated by polarized radiation, and the order parameters for various bands were determined in the IR region. From these data it is argued that phase 1 could be a smectic liquid crystal rather than a plastic crystalline phase.
ABSTRACT —This paper presents an interphase engineering technique suitable for grafting silane-mo... more ABSTRACT —This paper presents an interphase engineering technique suitable for grafting silane-modified polymers onto glass fibres to be used in composites with enhanced impact tolerance. The silane-modified polymers include ethylene polymers grafted with γ-methacryloxypropyltrimethoxysilane (MPS) and a copolymer of butyl acrylate (BuA) and MPS. The grafting of functionalized interphase materials onto glass fibres is performed in solution. By changing the concentrations of the solutions, different amounts of polymer can be deposited on the fibres. Water crosslinking of the polymer gives the possibility of producing stabilised interfacial polymer coatings over a range of thicknesses. It is concluded that acidic conditions (1) promote the grafting of silane-modified polymers on glass fibres and (2) for a given reaction time, increase the amount of crosslinked polymer in the interphase, i.e. yield more stable interphases. It is also likely that preserving acidic conditions at the fibre/polymer interface is important for maintaining bonding across the interface. It is shown that polystyrene/glass-fibre composites having SEBS at the interface are promising candidates for high-impact-tolerance composites.
Mosaic Solutions AS is developing a novel concept for conductive adhesives for use in electrical ... more Mosaic Solutions AS is developing a novel concept for conductive adhesives for use in electrical interconnection of solar modules. The goal is to provide an alternative to the current soldering process in module manufacturing, enabling lower process temperatures and reducing the amount of toxic elements, e.g. lead. The conductive adhesive is based on replacing solid silver flakes by polymer particles coated with a thin layer of silver. The main advantage of this concept, compared to conventional conductive adhesives, is a typical ten-fold reduction in silver consumption. We have investigated the electrical properties of conductive adhesives based on silver-coated polymer particles, and demonstrated the use of the conductive adhesive concept in module manufacturing. The results are promising, showing that the electrical conductivity is more than sufficient for use in solar modules, and that our conductive adhesive concept represents a promising and realistic alternative to soldering.
La presente invention concerne un vernis/vernis-laque ou un revetement de gel a base organique, d... more La presente invention concerne un vernis/vernis-laque ou un revetement de gel a base organique, de preference transparent et brillant capable de former des revetements presentant une resistance elevee a l'usure, ainsi que son procede de production. Ledit vernis/vernis-laque ou revetement de gel comporte une quantite controlee de particules de polymere inorganique presentant une taille sensiblement comprise entre 1 et 100 nm, les particules etant capables de constituer un reseau tridimensionnel independant du reseau organique du vernis-laque ou pouvant avoir des liaisons avec ledit reseau. De maniere caracteristique, les particules de polymere consiste en un produit reactionnel obtenu par des reactions d'hydrolyse et de condensation de composes de monomeres choisis parmi les groupes suivants: i) M(OR)n, ou ii) R'-M(OR)n, ou M est un ion metallique, et R est un groupe organique choisi parmi les groupes alkyle, alcenyle, aryle ou des combinaisons de tels groupes comprenant ...
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Papers by Keith Redford