Influence of temperature on the adsorption of water vapor by collagen and leather

Abstract

The adsorption of water vapor by co ll agen, commercial hide powder, and severa l leathe rs was determined at various relative humidities ranging from about 0 to 96 percent, at 28°, 50°, and 70° C. Determi nations were also made on chestnut a nd quebracho tann ins at 28° C at vari o us re lative humi dities. The results indicate that at 50-percent relative humidity the vari ation of moisture conte nt for 1 degree change in temperat ure is e quivale nt to t hat for 1 perce nt cha nge in relative hum id ity. A specia ll y pu rifi ed co llagen h as higher affinity for wate r tha n does hi de powder, showing that t he pr evio us chemi cal treatment in fluences adsor ption. The res ults obtain ed from t he exp eriments 011 t he tan nin s a nd t he h ide powder show that tanning does not decrease water vapor adsorptio n at relative humiditie below 70 percent.F rom t he resu lts of t he adso rption measureme nts, heats of adsorption we re calcul ated by m eans of t he Cla usius-Clapey ron and Brunauer, Emmett, and Teller eq uations. The leathe rs sh ow hi g her heats of adsorp tion for low moist ure regains th an does co llage n, indi cati ng that they co ntain so me g roups t hat a re more highly act ive' towa rd wate r tha n t hose in coll agen . F ree e ne rgy and e nt ropy values for the adsorption at 50° C are given. The efi'ect of hi g h temperat ures o n moisture adsorption is studi ed by su bjecting specimens to elevated temperatures and t he n determ ining th e adsorption at 28° C. Methods are give n for estim ating m oist ure eo ntent for conditions t hat have not been st udied expe rimentall y. T he change of wate r adso rption wit ll tempe rat ure can be expressed by a simple relation involving th e log of the perce ntage of water adso rbed and t he inverse of the absolu te tempe ratu re.

Studies on the effects of mixed light-thermal ageing on parchment by vibrational spectroscopy and micro hot table method

“…It is known that the moisture content (water) in parchment changes depending on the external conditions to which it is exposed, and this also causes changes in its physical-chemical properties [33,34]. For example, the temperature of denaturation of collagen in collagen-based materials is directly related to its moisture content [9,15].…”

The role of crosslinking treatment on the pore structure and water transmission of biocollagenic materials

“…4,[15][16][17][18] Worthy of special mention are the studies carried out by Fathima et al regarding the influence of shrinkage on the porous structure of skin and leather by means of mercury intrusion porosimetry, nitrogen adsorption, and scanning electron microscopy, 6,7 the effects of tanning process steps upon pore size distribution, 19 and of crosslinking on the hydration structure of collagen. 20 …”

Influence of temperature and moisture on the electrical properties of leather

“…This behavior i clearly shown by E' and cos 4> in the tabular data. The gradual tra nsition region occurs a t lower moisture conten ts in vegetable leather than in chrome lea ther or in hide, and may be directly rela tr.d to that moisture conten t range in which the slope of the hea t of adsorption cur ve is und ergoing its greatest change [20]. The appar ent differ ence in effects of moisture in the lowand high-moisture range may be considel'pd to b due to the decreased binding energy of the moisture with increasing moistur~ content.…”

“…This area has been calculated by Kanagy [20] from adsorption data. Since the fibers are composed of submicroscopic fibrils and moisture appears to penetrate the fibers, it would appear that the fibrillar surface area must playa role in these data.…”