Cold Curing Research Articles

Stevens' cure: a secret remedy.

At the outset of the twentieth century the British Medical Association began a campaign against the sale of ‘patent medicines’. Some of these were innocuous tonics or cold cures such as Beecham's pills, but others claimed to cure the incurable including consumption and cancer. The BMA commissioned a chemist to analyse the medicines and cost the ingredients. His results were published in a BMJ series called ‘Secret remedies’. The first articles appeared in 1907, and were such a success that they were reprinted as a book of the same name (Figure 1) in 19091. In editorials the BMJ subsequently noted with annoyance that press reaction had been mixed. The Daily Telegraph and the Manchester Guardian had accepted advertisements, but the Express, Star, Graphic and News of the World had not (and had refused to review the book). A few weeks later the BMA recorded that, despite this ‘conspiracy of silence’, sales were mounting. Altogether 150 000 copies of the book were sold in the UK and the Empire. In 1910-1914 further analyses were published in the BMJ, and More Secret Remedies was published in 1912. The emphasis of the campaign changed and, together with the pharmacists, the BMA successfully lobbied the Government to investigate the matter: a Select Committee on Patent Medicines was set up the same year. Figure 1 Secret Remedies (1909) Singled out both in Secret Remedies and in the BMJ articles was ‘Stevens' Consumption Cure’, which was being advertised with a money-back offer: ‘I do not say consumption is curable, but I say if you are consumptive I will guarantee to cure you or return your money in full’. According to the manufacturer the formula was 80 grains of umckaloabo root with 13½ grains of chichitse per ounce prepared according to British Pharmacopoeia methods. According to the BMA's chemist, ‘The medicine was a clear red liquid and analysis showed it to contain in 100 fluid parts, 23.1 alcohol, 1.8 glycerine, and 4 parts solids; about 1 part of tannin and 0.2 part ash. The solid substance agreed in all respects with the solids of decoction of krameria, or a mixture of this decoction with a little kino. The formula thus seems to be: Rectified spirit of wine... 23.7 parts, glycerine 1.8 parts, decoction of krameria (1 in 3) to 100 parts. Or it may be made with a tincture of krameria... estimated cost for 2 fl oz—1½ d’. Krameria or rhatany root is an astringent still used in herbal and homeopathic remedies.

Characterization of new acrylic bone cements prepared with oleic acid derivatives

Acrylic bone-cement formulations were prepared with the use of a new tertiary aromatic amine derived from oleic acid, and also by incorporating an acrylic monomer derived from the same acid with the aim of reducing the leaching of toxic residuals and improving mechanical properties. 4-N,N dimethylaminobenzyl oleate (DMAO) was used as an activator in the benzoyl-peroxide radical cold curing of polymethyl methacrylate. Cements that contained DMAO exhibited much lower polymerization exotherm values, ranging between 55 and 62 °C, with a setting time around 16–17 min, depending on the amine/BPO molar ratio of the formulation. On curing a commercial bone cement, Palacos® R with DMAO, a decrease of 20 °C in peak temperature and an increase in setting time of 7 min were obtained, the curing parameters remaining well within limits permitted by the standards. In a second stage, partial substitution of MMA by oleyloxyethyl methacrylate (OMA) in the acrylic formulations was performed, the polymerization being initiated with the DMAO/BPO redox system. These formulations exhibited longer setting times and lower peak temperatures with respect to those based on PMMA. The glass transition temperature of the experimental cements were lower than that of PMMA cement because of the presence of long aliphatic chains of both activator and monomer in the cement matrix. Number average molecular weights of the cured cements were in the range of 1.2×105. PMMA cements cured with DMAO/BPO revealed a significant (p<0.001) increase in the strain to failure and a significant (p<0.001) decrease in Young's modulus in comparison to Palacos® R, whereas ultimate tensile strength remained unchanged. When the monomer OMA was incorporated, low concentrations of OMA provided a significant increase in tensile strength and elastic modulus without impairing the strain to failure. The results demonstrate that the experimental cements based on DMAO and OMA have excellent promise for use as orthopaedic and/or dental grouting materials. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 88–97, 2002; DOI 10.1002/jbm.10092

Cold-Curing Epoxy Resins: Aging and Environmental Effects. I - Thermal Properties

The effects of physical and chemical aging have been investigated on two cold-curing epoxy adhesives. One of the two has been physically aged at different temperatures below its glass transition (i.e. 10, 23, 30 and 40°C) and then subjected to enthalpy relaxation measurements in a differential scanning calorimeter (DSC). According to recent literature, DSC studies have suggested that enthalpy relaxation gradually increases with aging time to a limiting value, depending on the temperature, until structural equilibrium is reached. Specimens of both adhesives, previously cured at room temperature for 10 days, have been aged in a dry-dark atmosphere or in a freezer (-20°C) for a prolonged time, measuring Tg and enthalpy relaxation at different time spans. When the structural equilibrium is reached, the samples aged in the dark-dry atmosphere exhibit Tg and relaxation peak values similar to those found in the earlier analysis for samples isothermally cured at 23°C. Samples aged at -20°C, the curing time suggested by suppliers, which was not sufficient to cure the adhesives completely, have glass transition temperatures that are always lower. The cured adhesives have also been exposed to natural weather for up to 36 months. Some samples, taken at different periods of time, have been analyzed in DSC. Other samples have been subjected to a de-aging procedure (24 hours at 50°C) before the thermal analysis. The natural exposition, regarded as chemical aging, determines a cycling change of Tg of both adhesives around average values slightly lower than the initial ones. This behavior cannot be erased by the de-aging procedure, which is able to delete only the effects due to physical aging. Enthalpy relaxation peaks, characteristics of physical aging, are observed only for exposed samples not subjected to de-aging procedure. These samples, finally, are subjected during the natural exposition to aging and de-aging processes taking place in non-isothermal conditions and, therefore, not predictable. The presented study must be regarded as a qualitative analysis of the aging phenomena taking place in cold curing epoxy resins.

Evaluation of LR white resin for histology of the undecalcified rat tibia

Histology of plastic embedded undecalcified bone represents a challenging problem to the histotechnologist. We outline here an exploration of LR White resin as a suitable medium for histologic study of undecalcified rat tibia. A procedure was developed for light microscopy of rat tibia embedded in LR White and sectioned by sawing-grinding technics. The specimens were fixed in 10% neutral buffered formalin or alcohol-acetic acid-formol, dehydrated in ethanol, defatted in chloroform followed by resin infiltration and heat-curing of embedded blocks. The procedure of dehydration, defatting, infiltration, and polymerization can be completed within 10 days. Cold curing with accelerator provided by the manufacturer did not yield superior results compared to blocks cured with heat. Thick sections were obtained using a diamond wire saw, attached to plexiform slides, then ground and polished. Surface staining with Von Kossa silver reagent or toluidine blue revealed satisfactory morphological preservation of the mineralized bone sections. Artifacts like small bubbles appeared occasionally and could not be avoided despite prolonged infiltration or cold curing of blocks. Our method is relatively simple for base-line histologic study of rat tibia. The method offers advantages such as easy adaptability, reliable stainability, contrast, and resolution of bone architecture and marrow cells. Two other embedding media, Micro-Bed resin and Unicryl, were also tested, but produced inferior results.

Use of fly ash in high performance industrial coatings

AbstractThe extender properties of fly ash, a waste byproduct of thermal power stations, were assessed and compared with those of conventional extenders. The development of protective and decorative industrial coatings as solvent borne, cold curing, two pack epoxy systems, using fly ash as an extender, is reported. The effects of fly ash on coating properties and film characteristics are also discussed. A two body (high stress) abrasion test was conducted to assess the abrasion resistance of the coatings. It is concluded that the properties of fly ash that contribute to its usefulness as an extender are its abrasion resistance, chemical inertness, low oil absorption, and low specific gravity. The coatings that were developed have shown improved corrosion and abrasion resistance and also better resistance to chemicals (5%Na2 CO3 , 1%NaOH, and 2%H2 SO4 ) and organic solvents (toluene and mineral spirit). Fly ash can be a cost effective substitute for conventional extenders in high performance industrial coa...

Relationship between the morphology of PMMA particles and properties of acrylic bone cements

Bone cements are mainly based on acrylie polymers, poly (methyl methacrylate) (PMMA) being the most representative. The curing process (cold curing) is the result of the free radical polymerization of a mixture of beads of PMMA and methyl methacrylate (MMA), initiated by benzoyl peroxide (BPO) and activated by the presence of a tertiary amine, the most classical being N,N-dimethyl-4-toluidine (DMT). In this work the results on the effect of the size and size distribution of PMMA beads and the concentration of DMT and BPO on the setting parameters, the residual monomer content and the mechanical properties (tension and compression) of the cured systems are presented. The use of relatively larger diameter PMMA beads improves the characteristic parameters of the curing process (decreasing the peak temperature and increasing the setting time), without detrimental effects on the mechanical properties of the cured cement.

The Damage Tolerance of Fire-Retardant Glass-Epoxy Laminates

Alumina trihydrate is an effective and widely used fire retardant and smoke suppressant, with several other incidental advantages, but it usually lowers the mechanical strength of thermosetting resins and laminates. This paper reports the extent of the reduction in the impact damage tolerance of glass-epoxy woven roving laminates, when measured by determining their compression strength retention after impact (CAI). Inserting aramid plies reduced rather than increased the damage tolerance at low impact energies, regardless of their position. Tentative reasons for this observation are offered. Other material changes were also investigated. The benefit of using a rubber toughening modifier (Hycar ATBN) in the epoxy matrix was confined to the lowest impact energy range. Changing the epoxy resin curing agent from a cold curing, mixed amine system to a hot curing piperidine one resulted in an improved compression strength before impact, and in some cases also an improvement in post-impact strength retention.

The Damage Tolerance of Fire-Retardant Glass-Epoxy Laminates

Alumina trihydrate is an effective and widely used fire retardant and smoke suppressant, with several other incidental advantages, but it usually lowers the mechanical strength of thermosetting resins and laminates. This paper reports the extent of the reduction in the impact damage tolerance of glass-epoxy woven roving laminates, when measured by determining their compression strength retention after impact (CAI). Inserting aramid plies reduced rather than increased the damage tolerance at low impact energies, regardless of their position. Tentative reasons for this observation are offered. Other material changes were also investigated. The benefit of using a rubber toughening modifier (Hycar ATBN) in the epoxy matrix was confined to the lowest impact energy range. Changing the epoxy resin curing agent from a cold curing, mixed amine system to a hot curing piperidine one resulted in an improved compression strength before impact, and in some cases also an improvement in post-impact strength retention.

Time Dependence of Hardness of Cold Cure Molded Flexible Foams and Its Importance for System Development

The first impression made by a car seat, and thus very important for the customer, is the hardness. This can be adjusted to specific requirements or preferences. However, in practice it is found that the hardness is not constant but increases under load. This is in contrast with the results of standardized hardness measurements, where the values decrease. This time dependence should be further examined, because it is also suggested to be different for TDI- and MDI-foams. To get a first insight, standard deformation cycles were applied before and after a high constant loading over 10-20 hours

Time Dependence of Hardness of Cold Cure Molded Flexible Foams and Its Importance for System Development

The first impression made by a car seat, and thus very important for the customer, is the hardness. This can be adjusted to specific requirements or preferences. However, in practice it is found that the hardness is not constant but increases under load. This is in contrast with the results of standardized hardness measurements, where the values decrease. This time dependence should be further examined, because it is also suggested to be different for TDI- and MDI-foams. To get a first insight, standard deformation cycles were applied before and after a high constant loading over 10-20 hours

Time Dependence of Hardness of Cold Cure Molded Flexible Foams and Its Importance for System Development

Time Dependence of Hardness of Cold Cure Molded Flexible Foams and Its Importance for System Development

Marine Grade Polyester Resins for Boat Building in the 1990s

Long-term evidence strongly supports the suitability of polyester resins for the construction of marine structures. However, misuse and incorrect selection has resulted in some distrust of their use for the manufacture of large structures. In this paper the issues surrounding the limitations of general purpose resins are discussed and cost-effective alternatives suggested which, if used correctly, can resist blister formation indefinitely. The mechanical performance of these systems is also discussed and compared with vinyl esters, epoxies and toughened resins. Under cold curing conditions isophthalic acid and isophthalic acid-neopentyl glycol based resins are more than adequate for resisting blister formation for, in some systems, in excess of 20 years at ambient temperatures and with laminate properties matching those of cold cured epoxy or vinyl ester systems. Examples are given of the effective combination of different resin systems where the main structural laminate is protected by an environmental barrier providing cost-effective structural composites suitable for all marine structures.

Marine Grade Polyester Resins for Boat Building in the 1990s

Long-term evidence strongly supports the suitability of polyester resins for the construction of marine structures. However, misuse and incorrect selection has resulted in some distrust of their use for the manufacture of large structures. In this paper the issues surrounding the limitations of general purpose resins are discussed and cost-effective alternatives suggested which, if used correctly, can resist blister formation indefinitely. The mechanical performance of these systems is also discussed and compared with vinyl esters, epoxies and toughened resins. Under cold curing conditions isophthalic acid and isophthalic acid-neopentyl glycol based resins are more than adequate for resisting blister formation for, in some systems, in excess of 20 years at ambient temperatures and with laminate properties matching those of cold cured epoxy or vinyl ester systems. Examples are given of the effective combination of different resin systems where the main structural laminate is protected by an environmental barrier providing cost-effective structural composites suitable for all marine structures.

Silicon-containing esters of ?-cyanoacrylic acid: synthesis and properties

A number of cyanoacetates have been synthesized: cyanoacetoxymethyitrimethylsilane (1), cyanoacetoxymethylpentamethyldisiloxane (2), cyanoacetoxyetoxymethylpentamethyldisiloxane (3). They were converted by the Knoevenagel reaction to novel esters of a-cyanoacrylic acid (4–13) containing silicon atoms in the ester groups and having the general formula RCH=C(CN)COOCH2X (where R=H, 4-MeOC6H4, MeCH=CH, 2-furyl; X=SiMe3, SiMe2OSiMe3, CH2OCH2SiMe2OSiMe3). These compounds are capable of copolymerization with esters of cyanoacrylic acid which are the precursors to adhesives for cold curing.

Cold curing epoxy systems for protection against heavy corrosion

Introduction Most corrosion protection systems used for maintenance, as well as binders for the building and civil engineering industries, are cold‐curing formulations. Elevated temperature cure is usually excluded by the size and shape of the substrate to be coated. Consequently, the selection of binders that are suitable for these surface protection systems is limited to those that combine the following properties:

Amides from N-phenylpiperazine as low-toxicity activators in radical polymerizations

N′-Acryloyl- (AcrNPP), N′-methacryloyl- (MetNPP) and N′-acetyl- N-phenylpiperazine (AcNPP) were synthesized and tested as activators in the benzoyl peroxide radical ‘cold curing’ of methyl methacrylate at 40°C. The three amides showed quite similar efficiencies as redox reducing agents, but different migrabilities from the final polymer. In amide release tests in methanol, the highest value was obtained with AcNPP; a notably lower release was observed with MetNPP and AcrNPP, the lowest being with the latter. This behaviour of the unsaturated amides is discussed in relation to their measured ability to copolymerize, as well as in relation to other factors affecting migrability.

Cold Cure, Prevention: Nothing to Sneeze At

Cold Cure, Prevention: Nothing to Sneeze At

A Chemical and Physical Comparison of Polyurethane Hot Cure and Cold Cure Moulding

A Chemical and Physical Comparison of Polyurethane Hot Cure and Cold Cure Moulding

Effect of a room temperature sodium dichromate/sulphuric acid etching pretreatment on the durability of aluminium alloy bonded joints

Practical constraints may restrict the method of surface pretreatment of aluminium alloy surfaces prior to bonding, and a need then arises for simpler techniques than those normally carried out, without a significant decrease in long term environmental durability of the bonded components. It is shown that use of the conventional sodium dichromate/sulphuric acid etching process at room temperature for a longer time, rather than at the specified 60–65°C, can produce equally durable joints and, with the particular alloy composition investigated, appears to show an improvement. Two cold curing modified epoxy adhesives were used to compare the performance of the hot and cold etching processes, respectively, and some limited testing was also carried out with several hot curing adhesives. Joint durability was assessed by water immersion of lap shear specimens and by wedge testing.

Dental plaque morphology as revealed by direct observation and by replicating techniques

The ability of four elastomer impression materials to reproduce details of bacterial plaque structures was studied by comparing areas of the replica models with corresponding areas of the replicated plaque. Plaque was grown on hydroxyapatite splint segments for 48 hours and replica models were made from three different resins. One of the resins, a methacrylate material, was not suited for this purpose due to its content of spherical particles. The polysulfide and polyether impression materials reacted with the heat curing epoxy resin, and less satisfactory results were obtained with cold curing epoxy resin. Best results were obtained by a combined use of low viscosity silicone impression materials and cold or heat curing epoxy resins as model materials. However, a considerable loss of detail occurred in the replica models compared with observations of plaque directly on splint surfaces. Outlines of individual bacteria could sometimes be seen in the models, but generally several cells seemed to fuse, and appeared like small globular structures where cells and pellicle were difficult to distinguish. The bacterial colonization started near the gingival border of the surface, initiated by attachment of individual bacteria to the pellicle surface.