Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-06-10
2003-06-10
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S451000, C524S404000
Reexamination Certificate
active
06576694
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to blends of carbon dioxide-propylene oxide copolymer and poly(3-hydroxyalkanoate) and a method of making the same.
BACKGROUND OF THE INVENTION
Carbon dioxide-propylene oxide copolymer (PPC) and poly(3-hydroxyalkanoate) (PHA) are completely biodegradable polymer materials. One of the main raw materials for synthesizing PPC is carbon dioxide produced in many industrial plants as an exhaust gas. Their exhaustion to the atmosphere not only causes pollution to the environment but also commits a waste of carbon resource. Through the synthesis of PPC, fixation of CO
2
resources could be achieved. This could provide a new carbon resource to partly alleviate the shortage of petrochemical raw materials and could at the same time protect the environment for the mankind. On the other side, since PPC possesses the characteristics of complete biodegradation, its use to substitute the non-biodegradable common plastics will have important meaning in solving the problem of “white pollution”. Therefore the present invention will have dual functions on environment protection. Carbon dioxide-propylene oxide copolymers are a kind of colorless and transparent solid. They are non-poisonous, tasteless and possess good barrier property, printing property as well as sealing property. They are especially suitable for the manufacture of disposal packaging materials for pharmaceuticals and foodstuff. Ever since Japanese scientists S. Inoue, H. Koinuma and T. Tsuruta disclosed and published this technology in Journal of Polymer Science, Polymer Letter Edition 7, 287 (1969) in the year of 1969, attentions from scientists worldwide were drawn to this result. Large amount of research and development works have been done. In China, Xiaojiang Zhao, Binyuan Liu, Xianhong Wang, Daqing Zhao and Fusong Wang et al have successively applied Chinese patents entitled “Method of making aliphatic polycarbonate with high molecular weight” (Chinese Patent 1,257,885A) and “Method of making rare earth composite catalyst” (Chinese Patent 1,257,753). However, PPC has a glass transition temperature of 37° C. When temperature exceeds 37° C., carbon dioxide-propylene oxide copolymers with alternating copolymer structure over 98% will turn into rubbery material. Their tensile strength, Young's modulus and flexural modulus will greatly be reduced and will lose the properties that a plastics material should have. Yet from another point of view, such rubbery PPC, especially those with higher degree of chain entanglement, is an excellent elastomer possessing very excellent toughness and therefore could be a good toughening agent for brittle polymeric materials.
Although PPC with low molecular weight has identical chemical composition to that of higher molecular weight PPC, its mechanical strength is much lower. Due to its lower molecular weight, the relative content of end group in the macromolecule increases, leading to an increase of the probability of an occurrence of zippering degradation induced by end group and thus a lowering of thermal stability. Since low molecular weight PPC does not possess the necessary mechanical properties of a plastics material, it could only be used as an additive for rubber.
In order to improve the properties of PPC, Robenson et al blended PPC with polyvinyl acetate and obtained a polyblend whose strength was twice that of PPC (L. M. Robenson, J. A. Kuphal, 1990 U.S. Pat. No. 4,912,149). When PPC was blended with acrylonitrile-butadiene rubber(NBR), the crosslinked polymer blend was formed with the initiators consisting of dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC), or DCP and maleic anhydride, then the polymer blend was turned into an elastomer of interpenetrating polymer network (IPN). This elastomer not only retained the good oil resisting property of acrylonitrile-butadiene rubber(NBR), but also significantly improved the mechanical properties. The thermooxidative stability of the elastomer was also excellent (Xianghong Yang, Yuhui Huang, Shulu Zhao et al , ZL91, 105, 618, 1, 1991). The properties of PPC were improved to a certain extent by the above-mentioned method of modification. The completely biodegradable characteristics of the material, however, were lost, leading to significant lowering of the environmental benefit.
PHA is also a kind of completely biodegradable polymer material. They could be prepared by biological fermentation of carbon resource materials such as glucose and propionic acid. These raw materials are a kind of renewable resources and as a kind of plastics they have important meaning on the alleviating of the petroleum resource shortage and on the realization of continued development of economy. Just like PPC, they are meaningful in solving the problem of “white pollution”. Since Lemoigne disclosed the technology of preparation of poly(3-hydroxyl butyrate) (PHB) in 1925 [M. Lemoigne, Ann. Inst. Pasteur (Paris), 1925, 39, 144-173.], attentions of scientists worldwide were drawn to it. Researches on PHB were developed to those of 3-hydroxylbutytate-3-hydroxyl valerate copolymers (PHBV) and other copolymers of PHA series. Large amount of patents were published such as U.S. Pat. No. 6,077,931 (Jun. 20, 2000), U.S. Pat. No. 4,603,070 (Jan. 1, 1986), U.S. Pat. No. 5,502,116 (March 1996) etc.
PHBV are a kind of thermoplastic and crystalline polymer. Their main shortcomings are relatively narrow temperature window of processing and easiness of decomposition and degradation. They are also a kind of brittle polymer materials with fairly low impact strength and relatively low elongation at break. In addition, in the course of processing, crystallinity increases on standing due to their relatively low rate of crystallization. Large spherulite thus formed can become a center of stress concentration. Owing to their high crystallinity, the amorphous part between spherulite sustains very high stress leading to possible breakage of the fabricated article along these regions. Due to slow crystallization rate, a film made from PHBV will stick to itself during film forming on cooling and the sticked parts are difficult to be separated off. The third drawback is their relatively low melt strength. All these disadvantages make PHB and PHBV very difficult to be processed into films. In order to improve these properties, scientists carried out a series of research and exploratory works. For example, B. Immirzi et al blended PHBV with polycaprolactone (PCL) to improve the properties of PHBV and studied in detail the effects of dicumyl peroxide (DCP) on the properties of PHBV/PCL blends [J. Mater. Sci. 1999, 34, 1625-1639]. M. Avella et al studied the properties of PHBV/starch reacted blends [J. Appl. Polym. Science, 2000, 77(1), 232-236]. Cyras et al studied the properties of PHBV/polyols blend system [Polymer International, 1999, 48, 705-712]. Park et al studied the properties of PHB/polyethylene blend [Polymer, 2001, 42, 5737-5742]. These works contribute to improve the properties of PHBV and to lower the cost of the preparation respectively, but there are still some problems to be solved. For example, the price of PCL is rather high and its effect on the toughness improvement of PHBV is unsatisfactory. Although the price of starch is low but nearly no improvements of toughness and main mechanical properties of PHBV could be achieved. Polyhydric alcohol polymer and polyoxyethylene although could improve the toughness of PHBV to a certain extent, yet the improvement is not sufficient. In addition, they are not biodegradable polymers. Their participation will lead to loss of completely biodegradable characteristics of the material.
SUMMARY OF THE INVENTION
One objective of the present invention is to provide blends of carbon dioxide-propylene oxide copolymer and poly(3-hydroxyalkanoate).
Another objective of the present invention is to provide a method of making said blends of carbon dioxide-propylene oxide copolymer and poly(3-hydroxyalkanoate).
DETAILED DESCRIPTION OF THE IN
Liu Jingjiang
Sun Chunrong
Changchun Institute of Applied Chemistry Chinese Academy of Scie
Knobbe Martens Olson & Bear LLP
Sanders Kriellion A.
LandOfFree
Blends of carbon dioxide-propylene oxide copolymer and poly... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blends of carbon dioxide-propylene oxide copolymer and poly..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blends of carbon dioxide-propylene oxide copolymer and poly... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3137915