Study On The Modification Of Poly(Butylene Succinate)

Poly(butylenes succinate)(PBS), whose synthetic raw material can be made from both oil and biological resources fermentation,is a kind of completely biodegradablepolyester.Of course it is been concerned by scientists andentrepreneurs. Compared with other biodegradable plastic, PBS has better mechanical properties and heat resistance.The thermal deformation temperature is close to100℃. PBSprocesses low molecular mass, high molten index, and poor mechanical performance, and in actual synthesis process it needs to be prepared in low pressure and high temperature, such disadvantages limit the applications of PBS.PBSis modified in this paperfrom three aspects:PBS was reacted with hexamethylene diisocyanate (HDI) used as a chain extender to produce higher molecular weight; And aftermodifying the calcium carbonate whiskers surface,mixed it with PBS in the intensive mixer to prepare PBS/modified CaCO3whisker composites;Blend ofPBSwith soyprotein isolate(SPI) with addition of methylene diphenyl diisocyanate (MDI) as a compatibilizer by using an intensive mixer. And theproperties of three kinds of modified materials aboveare studied.The main research andconclusions are as follows:PBS reacted with hexamethylene diisocyanate (HDI) used as a chain extender in the intensive mixer.Compared the characters of pure PBS and modified PBS through FTIR, characteristic viscosity, mechanical properties, melting index, heat resistance test et al. The results show that chain extender HDI have effective reactions with PBS producing ammonia methyl groups.After the chain extension,material'scharacteristic viscosity,tensile strength, bresking elongation, bending strength and impact toughness get a different degree of ascensionbut melting index decreased.When at the temperature of150℃,n(HDI):n(PBS)was2.5:1, the modified PBS has best comprehensive properties.Compared with the pure PBS,the increasing rangeof characteristic viscosity increases, tensile strength,breaking elongation,and the bending strength are respectively81.3%,16%,79.4%and27%.Molten index decreasesfrom39.2g/10min to14.91g/10min, besides the melting point of PBS improves and crystallinity decreased. Using HDI as chain extender is a feasible method to improve molecular weight, mechanical properties and processing properties of PBS.The calcium carbonate whiskers surface was modificate with silane KH-570,and then mixed it with PBS in the intensive mixer. Study the characteristics of the composite through mechanical properties, thermal, wide Angle X-ray diffraction and SEM.With Calcium carbonate whisker peak type of PBSdidn't change and found that when calcium carbonate whisker concent is5%it hasgood interface with resin matrix,which resulting that thecomposite material is brittle fracture, the tensile strength,breaking elongation, bending strength, melting point and crystallinity of the composite reach a maximum.As the content get further increasing, the composite turn to ductile fracture, and tensile strength, break elongation, bending strength, melting point and crystallinity drop. Because of calcium carbonate whisker's good thermal stability, it made the composite's thermal decomposition temperature turn up.Mixture of the soy protein isolate (SPI), poly(butylenes succinate)(PBS), and methylene diphenyl diisocyanate (MDI)which can recact with SPI and PBS asacompatibilizerin the intensive.Study the influence of composite with change of soy protein isolated (SPI) concent on the mechanical properties, melting index and degradation, and text the composite through infrared, X-ray diffraction, thermal properties and section scanning electron microscopy (SEM). MDI can reacted with-NH2-,-NH-and-OH group in SPI and-OH in PBS,which strengthen the composite's compatibility.The tensile strength,breaking elongationdecreased with the increase of the content of soybean protein isolate. When soybean protein isolated (SPI) content is low (less than20%), the bending strength increased withsoyprotein isolate.But when the SPI content is more than20%,the situation becomes opposite.The bending modulus increase with the content of SPI.The increase of molten index make the composite can get more use in flow extension and blow molding process.However, the SPI led the molten temperature and thermal decomposition temperature and molten enthalpy decreased, and in another word composite's thermal performance reduced.Mixing with SPIdoes not change the PBS's crystal shape and just only reduced the crystallinity of PBS. When SPI content was10%,it canscatter well in the matrix, the tensile strength, breaking elongation, bibulous rate and weightlessness rate hasn't fallen obviously.But with the increase of SPI content, the continuous phase formed and phase separation emerged and related characteristics fallen.