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Decomposable plastics containing starch and preparaton method

A technology for degrading plastics and starch, which is applied in the field of degradable plastics preparation, can solve the problems of cumbersome process, affecting material properties, and slow crystallization speed of PHB, etc., and achieve the effect of broad development and application prospects, simple operation process, and uniform mixing

Inactive Publication Date: 2005-01-12
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current problem is that the thermal stability of PHB is poor, the difference between its melting temperature and decomposition temperature is only about 10°C, it is easy to degrade, and it is difficult to process by the usual thermoplastic method; in addition, the crystallization speed of PHB is slow, and the products processed at high temperature It will not crystallize completely until it is placed at room temperature for 600 hours, and the post-crystallization will cause the product to be extremely brittle, which limits its application as a packaging material alone
However, the process is cumbersome and consumes high energy, and it is difficult to mix the pre-plasticized polyvinyl alcohol particles and starch evenly, which affects the material properties

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Mix the starch and polyvinyl alcohol evenly under stirring; the plasticizer is mixed in the weight ratio of water: glycerol: polyethylene glycol = 30.0: 39.5: 30.5 at 60°C; slowly spray the above plasticizer to the starch and polyvinyl alcohol. In the mixture of vinyl alcohol, wherein the weight ratio of starch: polyvinyl alcohol: plasticizer is 26:51:23, after stirring for 3 minutes, take out the mixture, and place it in a sealed bag at room temperature for 24 hours. The mixture is extruded through a twin-screw extruder, the temperature from the feed port to the discharge port is: 95 / 175 / 185 / 182 / 150°C, and the screw speed is 40 rpm.

[0036] The mixed material is extruded into rod shape, cooled and granulated, and then injection molded. The mechanical properties of the injection-molded standard sample are tested according to GB1040-79 as follows: breaking strength is 22.53MPa, elongation at break is 126.75%, and modulus of elasticity is 162.27MPa; according to GB1843-8...

Embodiment 2

[0038]Mix the starch and polyvinyl alcohol evenly under stirring; the plasticizer is mixed in a weight ratio of water: glycerol: polyethylene glycol = 27.2: 54.4: 18.4 at 60°C; slowly spray the above plasticizer to the starch and polyvinyl alcohol. In the mixture of vinyl alcohol, wherein the weight ratio of starch: polyvinyl alcohol: plasticizer is 51:26:23, after stirring for 3 minutes, take out the mixture, and place it in a sealed bag at room temperature for 24 hours. The mixture is extruded by a twin-screw extruder, the temperature from the feed port to the discharge port is: 95 / 179 / 185 / 183 / 149°C, and the screw speed is 40 rpm. The mixed material is extruded into rod shape, cooled and granulated, and then injection molded. The mechanical properties are as follows: the breaking strength is 21.90MPa, the breaking elongation is 26.90%, the modulus of elasticity is 507.88MPa, and the notched impact strength is 4.90Kgf-cm / cm.

Embodiment 3

[0040] Mix starch, polyvinyl alcohol and stearic acid evenly under stirring; the plasticizer is mixed at 60°C in a weight ratio of water: glycerol: polyethylene glycol = 30.0: 39.5: 30.5; slowly spray the above plasticizer Into the mixture of starch, polyvinyl alcohol and stearic acid, wherein the weight ratio of starch: polyvinyl alcohol: plasticizer: stearic acid is 24.6: 49.2: 25.7: 0.5, after stirring for 3 minutes, take out the mixed material, and put it under room temperature Store in an airtight bag for 24 hours. The mixture is extruded through a twin-screw extruder, the temperature from the feed port to the discharge port is: 100 / 175 / 175 / 173 / 150°C, and the screw speed is 40 rpm. The mixed material is extruded into rod shape, cooled and granulated, and then injection molded. The mechanical properties are as follows: the breaking strength is 26.97MPa, the breaking elongation is 145.76%, the modulus of elasticity is 97.2MPa, and the notched impact strength is 34.94Kgf-cm...

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Abstract

The plastic is mixture prepared from starch, poval, poly beta-hydroxybutyric acid ester or maleic anhydride grafted with poly beta-hydroxybutyric acid ester. The preparing method includes mixing starch in certain ratio with one or above materials of poval, poly beta-hydroxybutybic acid ester and said maleic anhydride, applying placticizer on the mixture and placing them in sealed bag at room temperature, taking out the material in bag and feeding it into extruder, and obtaining desired product through extruding, pelletizing and injection moulding.

Description

technical field [0001] The invention relates to a starch-containing degradable plastic and a preparation method thereof, belonging to the technical field of degradable plastic preparation. Background technique [0002] With the increasing number of plastic products, the "white pollution" caused by waste plastics has become a worldwide public hazard, and the development of degradable plastics has become a research hotspot worldwide. One of them is based on polyethylene, polypropylene, etc., and a photosensitive group is introduced into the main chain of the olefin polymer or a photosensitive chemical agent is added to the polymer to prepare a photodegradable plastic; Olefin as the main raw material, adding a small amount of natural polymers such as starch, is a biodegradable plastic made through a special processing technology. There are many patents about the above-mentioned products both at home and abroad at present, as CN85100494, CN1069471 etc. However, this type of pr...

Claims

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Application Information

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IPC IPC(8): C08L3/02C08L29/04
Inventor 杨冬芝胡平叶鹤荣
Owner TSINGHUA UNIV
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