Fractionation of phenol-formaldehyde reaction mixtures with gel permeation chromatography

Quinn, Edwin J.; Osterhoudt, H. W.; Heckles, John S.; Ziegler, Dominik

doi:10.1021/ac60259a002

Cited by 27 publications

(4 citation statements)

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“…However, in this set of experiments, after cure, specimens were cooled down to room temperature (while still stored in thick polyethylene bags) and fractured without reconditioning. We have observed from gel permeation chromatograms that adhesives cured at 85°C for 1 h, then exposed to a humid atmosphere do absorb some moisture*: An additional negative peak appears in the chromatogram; this peak has been attributed to water by Quinn et al 9 It is thus possible that reconditioning of specimens may lead to the inhibition of water by the adhesive layer. If this happens, a certain degree of adhesive plasticization will occur when specimens are reconditioned to 8% wood moisture content, and this could enhance the crack arrest capability.…”

Section: Discussionmentioning

confidence: 99%

Wood processing variables and adhesive joint performance

Ebewele

River

Koutsky

1986

J of Applied Polymer Sci

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SynopsisIn order to obtain a bonded wood product from the tree, wood must be subjected to a series of processes. These include, among others, vital processes like drying of the green wood and machining of the surfaces of the dried wood in preparation for bonding. However, when wood is machined with dull blades, thermal degradation of the wood frequently occurs. The effects of kiln drying and thermal degradation of wood on the performance of the adhesive joints subsequently formed from such wood were investigated. Tapered double cantilever beam (TDCB) test specimens obtained from hard maple and phenol-resorcinol-formaldehyde (PRF) adhesives were used in the investigations. The enhancement of fracture energy due to the reduction in the moisture content of wood, the improved performance of adhesive joints due to rejointing of wood surfaces before bonding, and the reduction of adhesive joint strength resulting from thermal degradation of wood are presented and discussed. INTRODUCTIONAdhesives are, by definition, substances capable of fastening materials together by surface attachment. Therefore, the success or failure of an adhesive in the peformance of this function depends very strongly on its ability to adhere to the materials being bonded. The success of the adhesion process itself is dictated partly but significantly by the topography of the adherends. Wood surface topography is a strong function of the processing variables. Going from the tree to the bonded wood product involves a number of processes. These include, among others, such vital factors as drying of the green wood, machining of the surfaces in preparation for bonding, and storage before bonding. We have previously reported the effects of surface roughness, the nature of surface roughness, and aging of machined surface (by storage) on adhesive joint fracture energy.Q In this paper we present results of studies on the effects of kiln drying and thermal aging of wood on adhesive joint performance. ADHESIVE JOINT STRENGTH MEASUREMENT-THE FRACTURE MECHANICS APPROACHFracture mechanics is a relatively new discipline which relates the fracturing behavior of flawed bodies to applied loads. Fracture mechanics is a direct outgrowth of the Griffith theory which postulates that the lower-* To whom all inquiries should be addressed. have developed and applied the tapered double cantilever beam (TDCB) geometry to a number of composite systems using metal adherends. We have adapted this for use in wood-based adhesive systems. Details of this have been given elsewhere. 1.2 Using the TDCB, the fracture energy is given by the equation G. G is related to K by the equations 4PZEb2 GIc = -m where P, = critial load necessary to cause a previously stationary or slowmoving crack to propagate abruptly, b = width of beam, m = a constant chosen so that compliance changes linearly with crack length [m = 0.52 cm-' (1.33 in.-1) for all specimens in this study], and E = bending modulus of adherends. At P,, the crack propagates until enough energy is released to bring the crack ...

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Section: Discussionmentioning

confidence: 99%

Wood processing variables and adhesive joint performance

Ebewele

River

Koutsky

1986

J of Applied Polymer Sci

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“…Manatt et al (9) employed 19F NMR spectrometry to determine these ratios in polyalkylene oxides which had been converted to trifluoroacetate esters. Gas-liquid chromatography (GLC), column chromatography, gel permeation chromatography, and thinlayer chromatography (TLC) have been used by numerous investigators to measure molecular weight distributions of oxyethylated p-alkylphenols or alcohols, and of polypropylene glycols (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). The following results and conclusions from these studies were of assistance to us in developing methods of determining oxyalkylate composition.…”

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confidence: 99%