Table 1.
Characteristics of selected PLA samples and information about experimental conditions.
| PLA Samples | DMA Experimental Conditions | Glass Transition Temperature (Tg, °C) 1 | Observations | Ref. |
|---|---|---|---|---|
| ▪ semi-crystalline PLLA from Boehringer Ingelheim (Resomer® (Mn 180,000, Mw 22 × 104 g mol−1) | Perkin Elmer DMA 7e: 3 °C/min; 1 Hz; 20–110 °C; loading mode: tension |
60 (tan δ peak) |
Investigation of the glass transition region The apparent unusual decrease of Tg with increasing crystallinity is associated with the changes in the thickness of the rigid amorphous phase. |
[32] |
| ▪ PLA 3051D type from Nature Works (4% D-lactide) | Perkin Elmer Diamond DMA: 2, 5, 10, 15, 20 °C/min; 1 Hz; 0–150 °C; loading mode: ns |
60–70 (onset of E’ drop) |
The whole behavior (also Tg) depends on the heating rate | [35] |
| ▪ PLLA from Boehringer, Ingelheim or synthesized in the laboratory | Polymer Laboratories DMTA 2: 2 °C/min; 1 Hz; 30–150 °C; loading mode: bending |
65 (tan δ peak) |
The effect of thermal treatment, processing conditions and molecular weight on crystallization phenomena occurring in the PLLA | [54] |
| ▪ PLLA from Boehringer (Resomer L206: Mv 20,000 and L214: Mv 691,000) or synthesized in the laboratory (Mv 5,300) | Polymer Laboratories DMTA: 3 °C/min; 3 Hz; −150–160 °C; loading mode: dual cantilever bending |
70 (tan δ peak) |
Dynamic mechanical characterization of optically active PLA depending on effect of physical ageing | [55] |
| ▪ PLA synthesized in the laboratory (~95% L-isomer) | Polymer Laboratories DMTA: 1 Hz; −150–150 °C; loading mode: ns |
50 (tan δ peak) |
Study of internal motions; Broad secondary relaxations mentioned near −50 °C |
[56] |
| ▪ PLA, 2002D type from Nature Works (4.25% D-lactic enantiomer) | Mettler Toledo DMA: Isothermal steps at 2°; 1 Hz; 20–140 °C; loading mode: three point bending |
58 (onset of E’ drop) |
PLA mechanically reprocessed up to 5 cycles The shortening of the first rubbery plateau denotes the chain cleavage |
[57] |
| ▪ PLA from Nature Works (92% L-lactide, Mw 9 × 104 g mol−1, PI 2.75) | TA Instruments DMTA V: 2 °C/min; 1 Hz; −140–130 °C; loading mode: tension |
67 (tan δ peak) |
Study of the effect of plasticizers like ATBC 3 and PEG 4; Broad β-relaxation centered at −80 °C. V-shape E’ vs. T plot. |
[58] |
| ▪ PLA 3052D type from Nature Works IngeoTM (Mw 13.9 × 104 g mol−1) | TA Instruments Q800 DMA: 3 °C/min; 1 Hz; −60–130 °C; loading mode: single cantilever bending |
65.6 (tan δ peak) |
Glass fiber-reinforced PLA composites | [59] |
| ▪ PLLA 4032D type from Nature Works (1.2–1.6% D-lactide, Mw 20.7 × 104 g mol−1, PI 1.74) |
Mettler Toledo DMA 1: 2 °C/min; 1 Hz; 30–100 °C; loading mode: tension |
60 (onset of E’ drop) |
Nanocomposites of PLLA with CNC 5 and modified CNC (with TMC 6 300); Improved HDT at T < Tm 7 |
[60] |
| ▪ PLA 2002D type from Nature Works (4.2% D-lactide, Mw 4 × 104 g mol−1) | Perkin Elmer Inc. DMA 8000 3 °C/min; −500–150 °C; loading mode: tension |
60 (onset of E’ drop) |
PLA composite films with 0.5–7.0 wt% CNF 8; Cold crystallization starts at the end of the glass transition: A slope change is noticed on E’vs. T during the glass transition. |
[61] |
| ▪ PLA 2003D type from Nature Works LLC (Mw 9.8 × 104 and 20 × 104 g mol−1) |
TA Instruments Q800 DMA: 1 °C/min; 1 Hz; 25–120 °C; loading mode: bending |
66 (tan δ peak) |
PLA nanocomposites with esterified cellulose nanocrystals | [62] |
| ▪ PLA 3251D type from Nature Works (Naarden, The Netherlands) |
Mettler Toledo DMA: 3 °C/min; 1 Hz; 0–160 °C; loading mode: dual cantilever bending |
60 (onset of E’ drop) |
PLA composites with BKSW 9 (15–35%) | [63] |
| ▪ PLA 4043D type from Nature Works (2% D-lactide, Mw 10 × 104 g mol−1) | TA Instruments Q800 DMA: 3 °C/min; 1 Hz; 20–140 °C; loading mode: bending |
70 (tan δ peak) |
PLA-trifluoropropyl-POSS 10 composites | [64] |
| ▪ PLA 3251D type from Nature Works (Mn 11.6 × 104 g mol−1) | TA Instruments Q800 DMA: 3 °C/min; 1 Hz; 0–100 °C; loading mode: single cantilever bending |
55 (onset of E’ drop) |
Graphene-PLA composites | [65] |
| ▪ PLA 290, Zhejiang, Haizheng Biological Materials Co. Ltd. (Dhejiang, China) | TA Instruments Q800 DMA: 3 °C/min; 1 Hz; −20–150 °C; loading mode: dual cantilever bending |
60 (tan δ peak) |
Nanocomposites of PLA with nanorod-shaped hybrid flame retardant based on ATH and BPA 11 | [66] |
| ▪ PLA REvode 201, Zhejiang Hisaiv Biomaterials | TA Instruments Q800 DMA: 3 °C/min; 1 Hz; 25–120 °C; loading mode: single cantilever bending |
50 (onset of E’ drop) |
PLA-talc composites; Cold crystallization is marked as a small peak the tan δ curve |
[67] |
| ▪ PLLA from Nature Works (3.8% meso-lactide, Mw 10.2 × 104 g mol−1) |
Rheometric Scientific DMTA Mark IV: Isostep mode; step 2 °C; 35–150 °C; loading mode: dual cantilever bending |
60 | PLA plates that were subjected to controlled degradation in soil test under controlled conditions (T, water, pH) Decrease of E’ in the glassy region as a result of formation of shorter chain Unusual sharp E’’ peak |
[68] |
| ▪ PLGA poly(lactide-co-glycolide) in the form of non-woven fabrics | Perkin Elmer Diamond DMA: 2 °C/min; 1 Hz; 0–150 °C; loading mode: tension |
55.5 (onset of E’ drop) 63 (tan δ peak) |
Degradation investigations of non-woven fabrics made from PLGA Emphasizing of shrinking during the glass transition |
[69] |
| ▪ PLA 4042D type from Nature works | Perkin Elmer DMA 7e: 5 °C/min; 1 Hz; 20–90 °C; loading mode: three-point bending |
59 (tan δ peak) |
Effect of nucleating agents (α-cyclodextrin, CaCO3, talc) on PLA/natural rubber mixtures A hump is noticed on the E’ vs. T curve, before Tg (enthalpic relaxation). |
[70] |
| ▪ PDLLA (L/DL 70/30), LR 708, CCA Purac Biochem, Gorinchem, Holland (Mw 22.6 × 104 g mol−1, PI 1.36) | Rheometric Scientific, Inc. MkIII DMTA: 3 °C/min; 1 Hz; −100–145 °C; loading mode: dual cantilever bending |
57.2 (E’’ peak) |
Investigations on amorphous PDLLA samples, deformed above Tg, at different compression ratios | [71] |
| ▪ PLA, Cargill-Dow (Mw 14.8 × 104 g mol−1, PI 1.9) |
TA Instruments DMA 2980: 2 °C/min; 1 Hz; 0–140 °C; loading mode: dual cantilever bending |
65 (onset of E’ drop) |
The plasticization effects exerted by ESO 12. ESO increases the ability of PLA to cold crystallization which starts right after the glass transition; the first rubbery plateau is absent. Unusual: tan δ peak height decreases with ESO content |
[72] |
| ▪ PLA, CML type, Hycail Finland Oy (Turku, Finland) | TA Instruments DMA Q800: 3 °C/min; 1 Hz; −90–140 °C; loading mode: tension |
60 (onset of E’ drop) |
PLA films plasticized with adipates (monomeric and polymeric structures) The plasticizers decrease the cold crystallization temperature. |
[73] |
| ▪ PLA (90% L-lactide, 8% mesolactide), 3001D type from NatureWorks (Mw 10.7 × 104 g mol−1, Mn 15.2 × 104) |
TA Instruments DMA Q800: 3 °C/min; 1 Hz; −20–200 °C; loading mode: tension |
61.9 (E’’ peak) 68.1 (tan δ peak) (linear PLA) |
Crosslinked PLA plasticized with DOP 13 | [74] |
| ▪ PLA (90% L-lactide, 8% mesolactide), from Cargill-Dow (Mw 4.9 × 104 g mol−1) |
TA Instruments DMA 2980: 1.5 °C/min; 1 Hz; −100–160 °C; loading mode: dual-cantilever bending |
67 (tan δ) |
Plasticization of PLA with thermoplastic starch | [75] |
| ▪ PLA, Fortum Corp. (Keilaniemi, Finland) Mw 10 × 104 g mol−1, PI 2.4 |
TA Instruments DMA 2980 3 °C/min; 1 Hz; −60–150 °C; loading mode: tension |
60 (onset of E’ drop) |
PLA films plasticized with oligomeric malonate esteramides | [76] |
| ▪ PLA with low and high stereogularity (13% D-lactide and 5% D-lactide) |
Polymer laboratories DMTA Mk II: 3 °C/min; 1 Hz; −60–80 °C; loading mode: tension |
60 (onset of E’ drop) |
Aging phenomena in PLA/PEG4
No cold crystallization for PLA with low stereogularity |
[77,78] |
| ▪ PLA 3001D type, Nature Works | TA Instruments DMA Q800: 3 °C/min; 1 Hz; −20–200 °C; loading mode: tension |
60 (onset of E’ drop) |
Crosslinked PLA, crosslinking agent: TAIC and DCP 14 Higher crosslinking degree means larger rubbery plateau |
[79] |
1 The glass transition temperature (Tg) of the neat PLA involved in the study; 2 DMTA: dynamic mechanical thermal analysis; 3 ATBC: acetyl tributyl citrate; 4 PEG: poly(ethylene glycol); 5 CNC: cellulose nanocrystals; 6 TMC: decamethylene dicarboxylic dibenzoyl hydrazide; 7 Tm: melting temperature; 8 CNF: cellulose nanofibrils; 9 BKSW: bleached kraft soft wood fibres; 10 POSS: polyhedral oligomeric silsesquioxane; 11 ATH: aluminium hydroxide, BPA: benzenephosphinic acid; 12 ESO: epoxidized soy bean oil; 13 DOP: dioctyl phthalate; 14 TAIC: triallyl isocyanurate, DCP: dicumyl peroxide.