Mechanical properties of crepe paper and chickpaper Mechanické vlastnosti krepového a “chickpaper“ papierov
The paper deals with the evaluation of the mechanical properties of the crepe paper and chickpaper. The thickness of crepe paper was 300 m with the surface mass 150 g*m and chickpaper paper thickness was 100 m with the surface mass 40 g*m. Crepe paper and chickpaper are usually used for chicken breeding. Longitudinal and transversal tensile properties were studied. The tensile behavior was monitored on the motorized test stand ANDILOG STENTOR 1000 (Andilog Technologies, Vitrolles, France).There were measured the tensile properties as modulus of elasticity, maximal elongation, maximal tensile force, tensile strengths, tensile index and strain at break of the longitudinal and transversal samples by testing paper strips. Mean values of the maximal elongation b of longitudinal chickpaper samples were three times smaller than maximal elongation of transversal samples. Mean values of maximal tensile force Ft, tensile strength  b tensile indexand maximal strain at break T of longitudinal chickpaper samples were two times smaller than maximal quantities of transversal samples. Mean values of the tensile modulus of elasticity of longitudinal and transversal chickpaper samples were almost equal. Chickpaper mechanical properties in tension were different in the longitudinal and transversal direction of the original paper surface. Mean values of the maximal elongation b and maximal strain at break T of longitudinal crepe paper samples were sixty times smaller than maximal elongation and maximal strain at break of transversal samples. Mean values of maximal tensile force Ft, tensile strength andtensile index w of longitudinal crepe paper samples were fourth times smaller than maximal quantities of transversal samples. Mean values of the tensile modulus of elasticity of longitudinal samples of crepe paper were thirty eight times smaller than values of transversal samples.
The influence of formation on tensile strength of papers made from mechanical pulps
The importance of paper formation is widely appreciated amongst papermakers in relation to sheet appearance, but much remains unclear about its role in paper strength, particularly for paper made from mechanical pulps. This paper addressed the question of how formation affects the tensile strength of such pulps. Two softwoods mechanical pulps from species of differing fibre length and coarseness were fractionated by fibre length and formed into handsheets at standard handsheet consistency and at a headbox consistency. As found by previous workers, handsheets from the shorter fibre fractions gave higher strength. These handsheets also had better formation, as expected from shorter fibres. To isolate the influence of formation from other factors which differ between species and fractions and may cause strength differences, we compared one fraction of one species at differing forming consistencies. This showed that the direct contribution of formation to tensile strength was significant, with poor formation giving lower strength for all fractions. In addition, we compared tensile strengths of whole pulps formed at standard handsheet consistency and headbox consistency at reduced grammages over the range 60-30 gsm.
Fibre Quality Factors in Papermaking — II The Importance of Fibre Coarseness
The effects of fibre coarseness on the papermaking properties of softwood pulps have been demonstrated. While reducing fibre length or strength reduces mainly sheet strength, changes in fibre coarseness influence virtually all pulp properties — drainage, wet-web strength, and the structural, strength, and optical properties of the dry sheets. The effects are large, and are explained on the basis that coarser fibres have thicker walls, are fewer per unit pulp mass, and have smaller specific surface area. Implications for the quality of market chemical pulps are discussed.