Recently, subjective or psycho-physical judgement has been recognized to be an important means for evaluating paper sheet. In this study, human judgement on properties such as stiffness or rigidity was examined by bending the pulp sheets which possess various basis weight over a range of 58-86 g/m
2. As a result of the tests, it is clear that the difference of stiffness or rigidity between sheets, gap of basis weight of which is about 5 g/m
2., can be judged precisely by subjective judgement.
Together with the human judgement of stiffness or rigidity of paper, Clark's stiffness was measured as an objective means to confirm the validity of the equation,
s=
ET3/12
W, where
s : Clark's stiffness,
E : Young's modulus,
T : thickness and
W : basis weight. As well-known, the values of
E and
T depend of the measuring method. When the thickness by means of mercury buoyancy method is adopted as
T, and the sonic modulus adopted as
E, the above equation is applicable to both, commercial pure paper and handmade sheet.
In addition to these results, there is a good relationship between such a human judgement and Clark's stiffness or rigidity.
抄録全体を表示