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1.
Crystallization behavior and biodegradation of poly(3-hydroxybutyrate) and poly(ethylene glycol) multiblock copolymers 总被引:1,自引:0,他引:1
Block copolymerization by using isocyanates is an effective method for incorporating PHB and PEG because it can prepare copolymers with good properties, such as toughness, strength, and so on. In this study, we adopted soil suspension system to estimate the biodegradability of a series of PHB/PEG multiblock copolymers with different compositions and block lengths. In the degradation process, the changes in weight loss, molecular weight, and tensile strength were periodically measured to determine the biodegradability, and the surface morphology was also observed by SEM. In contrast to pure PHB, the weight loss of the copolymer was relatively lower. On the other hand, the tensile strength and molecular weight experienced apparent decrease, and for BHG1000-3-1, they reached 46.7% and 77.7% of the initial value, respectively. SEM observation showed that the surface was covered with numerous erosion pits. All these indicate that the degradation indeed took place and long-chain molecules have been hydrolyzed into shorter ones. The crystallization behavior was also investigated by DSC and WAXD. The results showed that both the segments, PEG and PHB, can form crystalline phases at lower PHB contents ranging from 29% to 44%, and when PHB component was more than 60%, only PHB phase can crystallize. 相似文献
2.
Multiblock poly(ester-block-amide)s (PEA) elastomers comprising hard blocks of oligoamide and oligoester soft segments were prepared and their structure-property relations were analysed. The polycondensation reaction of oligoesters (prepared from 1,4-butanediol and dimerized fatty acid) with oligolaurolactam (PA12) gave copolymer series with variable blocks content (the soft segments content was varied from 24 to 60 wt.%). PEAs are the phase system composed of crystallised sequences of oligoamide (hard segment phase) as well as oligoesters (soft segment phase). Mixing between the hard and soft phases was studied by thermal and mechanical measurements (DSC, DMTA). These results have indicated on a multiphase structure of investigated materials. The relationship between the observed thermal and tensile properties and the soft/hard segments content indicated on an increase of the phase separation with soft segments content. 相似文献
3.
Mazerolles G Preys S Bouchut C Meudec E Fulcrand H Souquet JM Cheynier V 《Analytica chimica acta》2010,678(2):195-202
In the present study, direct flow injection mass spectrometry was investigated for rapid characterization of the polyphenolic composition of red wines. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) (in both positive and negative ion modes) have been simultaneously used for a more comprehensive analysis of the samples studied. In this way, four mass spectra have been recorded for each wine. Each spectrum was considered as a fingerprint related to the chemical composition. This methodology was applied to a large number of Beaujolais wines from different grades and different vintages.This data set was processed using a chemometrical multiblock analysis, which allowed to synthesize the whole information collected. The results obtained showed that the wine fingerprints address the composition of the main polyphenolic compounds present in the red wines and can discriminate groups of wines showing different polyphenolic compositions. Multiblock analysis appears as a very promising tool to deal with several data tables of multivariate signals in order to define, by combining the whole information, the best operating protocol according to the desired analytical objectives. 相似文献
4.
Regularized generalized canonical correlation analysis for multiblock or multigroup data analysis 总被引:1,自引:0,他引:1
This paper presents an overview of methods for the analysis of data structured in blocks of variables or in groups of individuals. More specifically, regularized generalized canonical correlation analysis (RGCCA), which is a unifying approach for multiblock data analysis, is extended to be also a unifying tool for multigroup data analysis. The versatility and usefulness of our approach is illustrated on two real datasets. 相似文献
5.
More than one multi-informative analytical technique is often applied when describing the condition of a set of samples. Often a part of the information found in these data blocks is redundant and can be extracted from more blocks. This study puts forward a method (multiblock variance partitioning—MVP) to compare the information/variation in different data blocks using simple quantitative measures. These measures are the unique part of the variation only found in one data block and the common part that can be found in more data blocks. These different parts are found using PLS models between predictor blocks and a common response. MVP provides a different view on the information in different blocks than normal multiblock analysis. It will be shown that this has many applications in very diverse fields such as process control, assessor performance in sensory analysis, efficiency of preprocessing methods and as complementary information to an interval PLS analysis. Here the ideas of the MVP approach are presented in detail using a study of red wines from different regions measured with GC-MS and FT-IR instruments providing different kinds of data representations. 相似文献
6.
A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation ext... 相似文献
7.
A series of poly(ethylene glycol)(PEG)-4,4′-diphenylmethanediisocyanate(MDI)-poly(dimethylsiloxane) (PDMS) multiblock copolymers were synthesized by employing two-step growth polymerization technique. Atomic force microscopy (AFM) observed nanoscopically well-organized phase-separated surfaces consisting of hydrophilic domain from PEG and MDI segments and hydrophobic domain from PDMS segments even with 50 wt.% PDMS in the copolymer, and the multiblock copolymer coatings presented a surface free energy of as low as 6-8 mN m−1. 相似文献
8.
Several papers have already stressed the interest of latent root regression and its similarities to partial least squares
regression. A new formulation of this method which makes it even simpler than the original method to set up a prediction model
is discussed. Furthermore, it is shown how this method can be extended not only to the case where it is desired to predict
several response variables from a set of predictors but also to the multiblock setting where the aim is to predict one or
several data sets from several other data sets. The interest of the method is illustrated on the basis of a data set pertaining
to epidemiology. 相似文献
9.
OnPLS is an extension of O2PLS that decomposes a set of matrices, in either multiblock or path model analysis, such that each matrix consists of two parts: a globally joint part containing variation shared with all other connected matrices, and a part that contains locally joint and unique variation, i.e. variation that is shared with some, but not all, other connected matrices or that is unique in a single matrix. 相似文献
10.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5-6):605-626
1,4-Bis(p-tert-butylphenylselenomethyl)benzene was used as a bifunctional photoiniferter for the polymerization of methyl methacrylate (MMA). Both the polymer yields and the number average of molecular weights ([Mbar]n) of polymers increased with the polymerization time and the [Mbar]n linearly increased with polymer yield. The addition of MMA to the poly(MMA) with irradiation increased the [Mbar]n of the polymer. Photoirradiation of telechelic polystyrene having phenylseleno groups at both ends as polymeric photoiniferter in the presence of MMA or p-chloromethylstyrene afforded effectively corresponding to the ABA type triblock copolymers. On the other hand, photopolymerization of p-methylstyrene with ABA type triblock copolymer of styrene and p-chloromethylstyrene as polymeric photoiniferter afforded to multiblock copolymer of styrene and p-substituted styrenes. 相似文献