The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy...The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy to avoid unacceptable discoloration and deterioration of thermal and mechanical properties caused by autocatalytic dehydrochlorination(DHC)during PVC processing.In this study,MAM with double bonds,amino groups,ester groups,and phospholipid groups was introduced into the chains of PVC to improve the thermal stability of PVC.The experimental results showed that the covalent attachment of MAM to PVC enhanced both the initial and the long-term stability of PVC.The enhanced performance of P-MAM-g compared with unmodified PVC is attributed to the simultaneous introduction of double bonds and amino groups into the PVC structure.The double bonds trapped the unstable chlorine atoms originated from the degradation of the PVC chain and reacted with the labile macromolecular radicals originated from PVC,thus inhibiting the radical degradation of the PVC chain.Furthermore,the amino groups absorbed the HCl produced in the degradation of PVC,inhibiting the adverse effects of HCl.P-MAM-g displayed better intrinsic flexibility and anti-migration ability of organic functional components compared with the control PVC materials.A possible stabilizing mechanism of the P-MAM-g was also presented.展开更多
Aralia spinosa leaves were collected from three different habitats in north Alabama. The leaf essential oils were collected by hydrodistillation and analyzed by gas chromatography / mass spectrometry (GC-MS). The most...Aralia spinosa leaves were collected from three different habitats in north Alabama. The leaf essential oils were collected by hydrodistillation and analyzed by gas chromatography / mass spectrometry (GC-MS). The most abundant components of A. spinosa essential oils were the sesquiterpenes germacrene D (28.0% - 37.3%), (E)-caryophyllene (8.2% - 15.7%), and α-humulene (1.9% - 4.9%);the monoterpene myrcene (up to 15.1%), and the fatty-acid-derivative (2E)-hexenal (trace to 28.9%). Fatty-acid derivatives and monoterpene hydrocarbons were more abundant in samples from suburban Huntsville than those from “natural” habitats (Monte Sano Mountain, Wheeler National Wildlife Refuge), while sesquiterpene hydrocarbons were more abundant in the natural/wild samples.展开更多
基金subsidized for the National Natural Science Foundation of China(21905117)and the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The development of PVC materials grafted with mannich base originated from myrcene(P-MAM-g,where the mannich base derived from myrcene is abbreviated as MAM)via green and effective synthetic methods is a good strategy to avoid unacceptable discoloration and deterioration of thermal and mechanical properties caused by autocatalytic dehydrochlorination(DHC)during PVC processing.In this study,MAM with double bonds,amino groups,ester groups,and phospholipid groups was introduced into the chains of PVC to improve the thermal stability of PVC.The experimental results showed that the covalent attachment of MAM to PVC enhanced both the initial and the long-term stability of PVC.The enhanced performance of P-MAM-g compared with unmodified PVC is attributed to the simultaneous introduction of double bonds and amino groups into the PVC structure.The double bonds trapped the unstable chlorine atoms originated from the degradation of the PVC chain and reacted with the labile macromolecular radicals originated from PVC,thus inhibiting the radical degradation of the PVC chain.Furthermore,the amino groups absorbed the HCl produced in the degradation of PVC,inhibiting the adverse effects of HCl.P-MAM-g displayed better intrinsic flexibility and anti-migration ability of organic functional components compared with the control PVC materials.A possible stabilizing mechanism of the P-MAM-g was also presented.
文摘Aralia spinosa leaves were collected from three different habitats in north Alabama. The leaf essential oils were collected by hydrodistillation and analyzed by gas chromatography / mass spectrometry (GC-MS). The most abundant components of A. spinosa essential oils were the sesquiterpenes germacrene D (28.0% - 37.3%), (E)-caryophyllene (8.2% - 15.7%), and α-humulene (1.9% - 4.9%);the monoterpene myrcene (up to 15.1%), and the fatty-acid-derivative (2E)-hexenal (trace to 28.9%). Fatty-acid derivatives and monoterpene hydrocarbons were more abundant in samples from suburban Huntsville than those from “natural” habitats (Monte Sano Mountain, Wheeler National Wildlife Refuge), while sesquiterpene hydrocarbons were more abundant in the natural/wild samples.
