CN1865347A

CN1865347A - Method for improving heat property and crystallization behavior of polylactic acid and its multiple blocked copolymer

Info

Publication number: CN1865347A
Application number: CN 200610026297
Authority: CN
Inventors: 余木火; 徐红; 滕翠青; 韩克清
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2006-04-30
Filing date: 2006-04-30
Publication date: 2006-11-22
Anticipated expiration: 2026-04-30
Also published as: CN100478396C

Abstract

The invention discloses a modified polylactic acid and multi-block copolymer heat property and crystallization behavior method, which comprises the following steps: (1) dissolving L-polylactic acid and multi-block copolymer and D-polylactic acid and multi-block copolymer in the carrene or chloroform at 1:1 rate; stirring the mixture liquid until dissolving evenly; (2) pouring the blending liquid on the culture dish; evaporating naturally for 1-3 days at indoor temperature; extracting into vacuum; storing the polylactic acid composition at indoor temperature. The invention adopts composite modified polymerization crystallization behavior to avoid adding out-phase nucleation agent, which improves the heat-durability in the final manufacturing course.

Description

Improve the method for poly(lactic acid) and segmented copolymer thermal characteristics and crystallization behavior

Technical field

The present invention relates to a kind of organic polymer material, particularly relate to a kind of method of improving poly(lactic acid) and segmented copolymer thermal characteristics and crystallization behavior, can be used for preparing the high-performance poly lactate material.

Background technology

Poly(lactic acid) is a kind of reproducible biodegradable material, has excellent biological compatibility.Poly(lactic acid) is nontoxic, degradable, can regenerate, and meets the requirement of environmental protection and Sustainable development, thereby more and more receives investigation of materials person and business people's concern.

Because generally resins for universal use is low, crystallization velocity is slow for the fragility height of poly(lactic acid), fusing point, thereby has limited its application as general-purpose plastics.For the fragility of improving poly(lactic acid), improve its molecular weight, many investigators have adopted the method for copolymerization that it is carried out modification, but after the copolymerization, because the adding of copolymerization component, the lactic acid segment is spaced, thereby makes the fusing point of poly(lactic acid) lower, crystallinity becomes poorer.In order to improve the crystallization property of poly(lactic acid) and lactic acid copolymer, Urayama etc. have reported that in Polymer 2003:44:5635-5641 adding the heterogeneous nucleation agent in poly(lactic acid) and lactic acid copolymer improves their crystallinity, find that talcum powder is the best nucleator of poly(lactic acid), but the mechanical property of the adding of inorganic nucleator possibility impact polymer.For example Ramos etc. reports in Polym.Composites 1988:9:105, after talcum powder joins in isotatic polypropylene and the poly co-mixing system as nucleator, when improving its crystal property, has also reduced the toughness of system.

Because poly(lactic acid) has opticity, Ikada etc. have reported the earliest that at Macromolecules 1987:20:904-906 carrying out blend with L-poly(lactic acid) (PLLA) and D-poly(lactic acid) (PDLA) by 1: 1 prepares the PLLA/PDLA mixture, thereby improve the thermal characteristics of PLLA.Recently also there is report to carry out compound (Portinha D, Bouteiller L, Pensec S, RichezA.Macromolecules 2004:37 (9): 3401-3406) with di-block copolymer PLLA-PCL and PDLA-PCL.But because in pure poly(lactic acid) and poly(lactic acid) di-block copolymer, the lactic acid segment all is ordered arrangement.But in the segmented copolymer of lactic acid, the lactic acid segment is a lack of alignment, can form composite structure between many embeddings of high molecular lactic acid end multipolymer of low-molecular-weight pure poly(lactic acid) and lactic acid segment lack of alignment and two kinds of high-molecular weight lactic acid segmented copolymers, not appear in the newspapers.The present invention aims to provide a kind of method of improving poly(lactic acid) and lactic acid segmented copolymer thermal characteristics and crystallization behavior with composite algorithm.

Summary of the invention

Technical problem to be solved by this invention provides a kind of method of improving poly(lactic acid) and segmented copolymer thermal characteristics and crystallization behavior, to remedy the deficiencies in the prior art or defective, meets the demands of production and living.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of method of improving poly(lactic acid) and segmented copolymer thermal characteristics and crystallization behavior comprises the steps:

(1) be that 1: 1 L-poly(lactic acid) (L-Polylactic acid is called for short PLLA) or its segmented copolymer and D-poly(lactic acid) (D-Polylactic acid is called for short PDLA) or its segmented copolymer are dissolved in methylene dichloride (CH with mass ratio ₂Cl ₂) or trichloromethane (CHCL ₃) in, after treating fully to dissolve, stirring makes it to mix under the room temperature;

(2) mixing solutions that mixes is poured on the culture dish, volatilized 1～3 day naturally under the room temperature, vacuumized again 1～3 day, obtain the mixture of poly(lactic acid), will deposit under the mixture room temperature.

As optimized technical scheme: described PLLA segmented copolymer is a kind of or its mixture in the segmented copolymers such as PLLA and polycaprolactone, Resins, epoxy, rubber, polyester diol, vulcabond.

Described PDLA segmented copolymer is a kind of or its mixture in the segmented copolymers such as PDLA and polycaprolactone, Resins, epoxy, rubber, polyester diol, vulcabond.

Described PLLA and PDLA weight-average molecular weight are 3000～100000.

The present invention is dissolved prior synthetic L type poly(lactic acid) or segmented copolymer by a certain percentage, is mixed with D type poly(lactic acid) or segmented copolymer; Then the solution that mixes is poured out, solvent flashing, vacuumized, obtain the mixture of L type and D type poly(lactic acid).

The molecular structural formula of poly(lactic acid) and lactic acid segmented copolymer building-up reactions is as follows:

Method of the present invention can be divided into for two steps:

The mixing solutions of two kinds of enantiomers of the first step preparation; The second step mixing solutions solvent evaporates obtains mixture.

The invention has the beneficial effects as follows:

1. adopt composite algorithm to improve the crystallization behavior of polymkeric substance, avoided the adding of heterogeneous nucleation agent, can not reduce the mechanical property of polymkeric substance, can improve the processing characteristics of polymkeric substance.

2. the fusing point of poly(lactic acid) and Tc improve after compound, and the thermotolerance of post-treatment process is improved.

Description of drawings

The DSC spectrogram of Fig. 1 PLLA, PDLA and PLLA/PDLA mixture

The X-ray diffractogram of Fig. 2 PLLA

The X-ray diffractogram of Fig. 3 PLLA/PDLA mixture

Fig. 4 PLLA is at the polarizing microscope photo of 120 ℃ of isothermal crystals in the time of 9 minutes

Fig. 5 PLLA/PDLA mixture is at 0.5 minute polarizing microscope photo of 130 ℃ of isothermal crystals

Fig. 6 PLLA/PDLA mixture is at 14 minutes polarizing microscope photo of 180 ℃ of isothermal crystals

The DSC spectrogram of Fig. 7 PLLA-BisA and PLLA-BisA/PDLA mixture

The X-ray diffractogram of Fig. 8 PLLA-BisA

The X-ray diffractogram of Fig. 9 PLLA-BisA/PDLA mixture

Figure 10 PLLA-BisA is at the polarizing microscope photo of 115 ℃ of isothermal crystals in the time of 20 minutes

Figure 11 PLLA-BisA/PDLA mixture is at 0.5 minute polarizing microscope photo of 130 ℃ of isothermal crystals

Figure 12 PLLA-BisA/PDLA mixture is at 20 minutes polarizing microscope photo of 170 ℃ of isothermal crystals

Embodiment

Below in conjunction with specific embodiment the present invention is further elaborated, with reference to accompanying drawing 1-12.

Embodiment 1:

Get weight-average molecular weight and be each 1g of PDLA, PLLA of 30000, be dissolved in respectively in the 13ml methylene dichloride, fully after the dissolving, pour in the wide-necked bottle and mix, the normal temperature lower magnetic force stirs 2h, is poured on then on the culture dish, volatilizees 3 days naturally under the room temperature, put into vacuum drier again and vacuumized 3 days, room temperature deposited for 2 weeks then.

Fig. 1 is the polylactic acid composition of present embodiment preparation and the DSC spectrogram of isomer thereof, from spectrogram as can be seen, the fusing point of PLLA, PDLA and PLLA/PDLA mixture is respectively 155.1,153.2 and 216.1 ℃, and the fusing point of mixture has improved 60 ℃ than the fusing point of isomer.Fig. 2 is the X-ray diffractogram of present embodiment PLLA, Fig. 3 is the X-ray diffractogram of PLLA/PDLA mixture, identical because of the X-ray diffractogram of PDLA and PLLA, here do not list, the X-ray diffraction spectrogram that Fig. 2 and Fig. 3 and Ikada etc. report in Macromolecules 1987:20:904-906 is identical, has proved the structure that forms mixture.Fig. 4 is that present embodiment PLLA is at the polarizing microscope photo of 120 ℃ of isothermal crystals in the time of 9 minutes, Fig. 5 be the PLLA/PDLA mixture at 0.5 minute polarizing microscope photo of 130 ℃ of isothermal crystals, Fig. 6 is that the PLLA/PDLA mixture is at 14 minutes polarizing microscope photo of 180 ℃ of isothermal crystals.From Fig. 4, Fig. 5, Fig. 6 as can be seen, the PLLA homopolymer is at 120 ℃ of isothermal crystals in the time of 9 minutes, form single big spherocrystal, be higher than this temperature, do not have crystal formationly, and the PLLA/PDLA mixture is in the time of 130 ℃, a large amount of little crystal grain appear rapidly, and take whole zone rapidly, even (180 ℃ time) still have the intact spherocrystal of growth to occur more than the fusing point of PLLA, PDLA, the easier crystallization of PLLA/PDLA mixture is described and has more stable crystalline form.

Embodiment 2:

Get PDLA (Mw=3.0 * 10 ⁴) and PLLA-bisphenol A epoxide resin segmented copolymer (PLLA-BisA) (Mw=1.7 * 10 ⁵) each 1g, being dissolved in 20ml concentration respectively is in the 0.2g/ml methylene dichloride, fully after the dissolving, pour in the wide-necked bottle and mix, the normal temperature lower magnetic force stirs 2h, is poured on the culture dish then, naturally volatilized 2 days under the room temperature, put into vacuum drier again and vacuumized 3 days, room temperature deposited for 1 week then.

Fig. 7 is the mixture of present embodiment preparation and the DSC spectrogram of isomer thereof, and as can be seen, the fusing point of PLLA-BisA and PLLA-BisA/PDLA mixture is respectively 137.5 ℃ and 193.3 ℃ from spectrogram, and the fusing point of mixture has improved 56 ℃.Fig. 8 is the X-ray diffractogram of PLLA-BisA, and Fig. 9 is the X-ray diffractogram of PLLA-BisA/PDLA mixture.As can be seen from Figure 8, PLLA-BisA X ray diffracting spectrum before compound is a very wide diffraction peak, illustrate that PLLA-BisA is non crystallized basically, and the position of the diffraction peak of Fig. 9 and Fig. 3 is identical, illustrates that PLLA-BisA and PDLA have formed composite structure.Figure 10 is that present embodiment PLLA-BisA is at the polarizing microscope photo of 115 ℃ of isothermal crystals in the time of 20 minutes, Figure 11 be the PLLA-BisA/PDLA mixture at 0.5 minute polarizing microscope photo of 130 ℃ of isothermal crystals, Figure 12 is that the PLLA-BisA/PDLA mixture is at 20 minutes polarizing microscope photo of 170 ℃ of isothermal crystals.As can be seen from Figure 10, the PLLA-BisA homopolymer is at 115 ℃ of isothermal crystals in the time of 20 minutes, basically do not have crystal to occur, PLLA-BisA to then occurred after PDLA is compound to embodiment 1 in the similar crystalline polamer of PLLA/PDLA mixture, this analytical results with X-ray diffraction is consistent.

Embodiment 3:

Get each 5g of PDLA used among the embodiment 1, PLLA, putting into and filling 50ml trichloromethane concentration is that the wide-necked bottle of 0.2g/ml seals, after dissolved the separating, magnetic agitation 4h, polymers soln is mixed, be poured on then on the release paper, volatilized 3 days naturally under the room temperature, put into vacuum drying oven again and vacuumized 3 days, room temperature was deposited 30 days then.Carry out DSC to 30 days mixture and measure depositing, recording its fusing point is 215.7 ℃.

Embodiment 4:

Get each 2g of PDLA used among the embodiment 2 and PLLA-BisA, putting into and filling 30ml trichloromethane concentration is the wide-necked bottle of 0.2g/ml, after dissolved the separating, magnetic agitation 2h, polymers soln is mixed, be poured on then on the release paper, volatilized 1 day naturally under the room temperature, put into vacuum drier again and vacuumized 1 day, room temperature was deposited 15 days then.Carry out DSC to 15 days mixture and measure depositing, recording its fusing point is 194.2 ℃.

Claims

1, improves the method for poly(lactic acid) and segmented copolymer thermal characteristics and crystallization behavior, it is characterized in that comprising the steps:

(1) be that 1: 1 L-poly(lactic acid) or its segmented copolymer and D-poly(lactic acid) or its segmented copolymer are dissolved in methylene dichloride or the trichloromethane with mass ratio, treat fully dissolving after, stir under the room temperature and make it to mix;

2, method according to claim 1 is characterized in that: described L-poly(lactic acid) segmented copolymer is a kind of or its mixture in the multipolymers such as L-poly(lactic acid) and polycaprolactone, Resins, epoxy, rubber, polyester diol, vulcabond.

3, method according to claim 1 is characterized in that: described D-poly(lactic acid) segmented copolymer is a kind of or its mixture in the multipolymers such as D-poly(lactic acid) and polycaprolactone, Resins, epoxy, rubber, polyester diol, vulcabond.

4, method according to claim 1 is characterized in that: described PLLA and PDLA weight-average molecular weight are 3000～100000.