Zobrazeno 1 - 10
of 19
pro vyhledávání: '"Mika Härkönen"'
Publikováno v:
Silva Fennica, Vol 54, Iss 1 (2020)
The time consumption (TC) of pre-commercial thinning (PCT) varies greatly among sites, stands and forest workers. The TC in PCT is usually estimated by field-assessed work difficulty factors. In this study, a linear mixed model for the TC in PCT was
Externí odkaz:
https://doaj.org/article/146dea535ac54546a89246c622cf0074
Publikováno v:
Silva Fennica, Vol 54, Iss 1 (2020)
The time consumption (TC) of pre-commercial thinning (PCT) varies greatly among sites, stands and forest workers. The TC in PCT is usually estimated by field-assessed work difficulty factors. In this study, a linear mixed model for the TC in PCT was
Publikováno v:
Journal of Applied Polymer Science. 64:865-873
A two-step process for lactic acid polymerization is studied: in the first step the lactic acid is condensation-polymerized to a low-molecular-weight hydroxyl-terminated prepolymer; and then the molecular weight is raised by joining prepolymer chains
Publikováno v:
Journal of Applied Polymer Science. 63:1865-1872
Copolymers of L-lactic acid (LLA) with DL-mandelic acid (DLMA), 4-hydroxybenzoic acid, 4-acetoxybenzoic acid, DL-malic acid, or anhydrous citric acid were synthesized via direct copolycondensation in the presence of 1,4-butanediol, using stannous oct
Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis
Publikováno v:
Journal of Applied Polymer Science. 63:1091-1100
We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains
Publikováno v:
Macromolecules. 30:373-379
The synthesis of low molecular weight (Mn(NMR) < 27 000 g/mol) lactic acid polymers by condensation polymerization of l-lactic acid was investigated. All polymerizations were carried out in the melt, using different catalysts and polymerization tempe
Publikováno v:
Macromolecules. 29:8677-8682
The synthesis of low molecular weight (Mn (NMR) < 7000 g/mol) lactic acid prepolymers by condensation polymerization of l-lactic acid was investigated. Besides the l-lactic acid polymer, hydroxyl- and carboxyl-terminated telechelic prepolymers were a
Publikováno v:
Journal of Macromolecular Science, Part A. 32:857-862
Aliphatic polyesters, such as poly(lactic acids), need high molecular weight for acceptable mechanical properties. This can be achieved through ring-opening polymerization of lactides. The lactide route is, however, relatively complicated, and altern
Publikováno v:
Polymer. 36:1499-1505
The results of experiments with a supported Ziegler-Natta catalyst were interpreted by a two-site model of the active sites, in order to enhance the understanding of multiple types of catalyst active sites and in particular the role of the external d
Publikováno v:
Macromolecular Symposia. 89:173-180
The formulae for conditional probabilities are derived with the term of NMR triad tacticities for the polymers whose polymerization process is described by an asymmetric Markovian process. The formulae obtained are applied to the polypropylene polyme